2009 Society for Medical Anthropology Conference: The Intersection of Anthropology and Medicine as Portrayed in Paul Farmer’s Photo Album

Paul Farmer, physician, anthropologist, and author, spoke at the 2009 Society for Medical Anthropology Conference at Yale University in September.Medical anthropology is a very young field, only approximately 50 years old. The underpinnings of medical anthropology have been around for some time, but as a discipline, the burden to ensure that it continues to flourish and grow belongs to future generations of students and scholars. However, future generations of medical anthropologists cannot carry the field forward unless they examine the teachings of previous teachers and scholars. By narrating his own story, just as he so frequently narrates the intricacies of Haiti [1], Paul Farmer, physician, anthropologist, and author of Pathologies of Power: Health, Human Rights, and the New War on the Poor [2], displayed a parallel between the stories of his own past with that of medical anthropology.At the 2009 Society for Medical Anthropology Conference at Yale University in September, Farmer began his aptly titled presentation, Photo Album, with a discussion of his introduction to medical anthropology while an undergraduate at Duke. He stumbled upon medical anthropology quite by chance as an ambitious pre-med who was interested in taking every course that had the word “medical” in its title. He credited many people, including Patricia Pessar, Arthur Kleinman, and Linda Garro with aiding the development of his ideas and perception of the world and teaching him to use medical anthropology not only in passive observation, but in the active practice of medicine. You “don’t have to be a faculty member to teach,” stressed Farmer. Some of the most important lessons to learn come from the poor, to whom few listen.Farmer believes that listening can form the work we do. He honed his listening skills, which are used in anthropology in an ethnographic context, after his first night in an emergency room, when he saw that many minor cases were brought in solely because individuals had no other outlet for treatment. Being a good listener allowed Farmer to understand the full impact of a 1981 slavery case involving migrant workers in Florida. It was this skill of listening that enabled Farmer to understand and tell Haiti’s story, as well as understand the intricate web that exists between privilege and privation. Just as the line between medical anthropology and primary care is often blurred, the “bracing connection between privilege and privation” becomes even more apparent the longer one spends studying both extremes.This is a vantage point Farmer was particularly susceptible to, given his trips from Haiti to Harvard and back again. Listening to his patients in Haiti and the United States would allow Farmer to draw parallels of inequality and injustice that exist for the impoverished in both places. The only difference between the United States and Haiti is that eventually many impoverished individuals in the United States will wind up in somewhat adequate medical facilities. In the story of global economics, Farmer said, “Good things get stuck in customs and bad things get traded freely.” A practicing physician may easily note that inequalities between the rich and poor are not unique to the United States or to Haiti, but what, Farmer asks, can anthropologists say about this division?The cursory glance through Farmer’s photo album ended with a picture of friends whom he fondly termed “the structural violence mafia” and anthropological ideas regarding unequal access to health care. While at first, the portion of anthropology that dissects the structures of violence seems isolated from medical anthropology, those structures of violence institute the vast inequalities that cause medicine to seem inaccessible. Farmer also stressed that “how we think about social theory influences global health.” Work in Haiti taught Farmer firsthand about the phenomenon of blaming the victim [3]. To understand this entrenched system of structural violence fully, an intensive bio-social analysis must be undertaken. Structural violence results in a system in which the victims are blamed, empowering those who suppress the victim while inhibiting the victim’s access to health care. Pointing fingers at the vulnerable is illustrated by the fact that Haiti is often blamed for the introduction of AIDS into North America [4,5]. Farmer stressed not only the inherent trauma of structural violence, but Carolyn Nordstrom’s ideas on violence having a distinct tomorrow [6]. The perpetual cycle of structural violence enables this concept of violence having a clear future with the inherent cultural systems that allow for violence remaining stagnant while the individuals entrapped within the system change.Beyond this concept of structural violence is that of structural healing [3]. Though structural healing is a new phenomenon being examined by anthropologists, it provides a balance to structural violence with the idea being that there are certain societal standards that are either in place or can be introduced that allow for an alleviation of the suffering caused by structural violence. While Farmer’s discussion of the path that led him to his current position was inspirational in itself, the sharing of his story is of even more importance because he has been a teacher to so many. His story reinforces the idea that even though structural violence has a definite past and future, so do medical anthropology and the idea of structural healing. Thankfully, medical anthropology may be used as a relatively new force to combat structural violence. Farmer’s speech may have been unexpected in its autobiographical content, but perhaps the main point is that the intersection between medicine and anthropology can be seen not as a single point but a line that runs the full length of each of these disciplines. We all have a distinct responsibility to not only hear but to listen and learn, not to just passively observe, but actively understand. It is with this listening and acting, that future medical anthropologists can bridge the gap between social sciences and practical medicine.     

2009 Society for Medical Anthropology Conference: Changing Anthropology,Changing Society

Fifty years after the founding of the field of medical anthropology, the Society for Medical Anthropology of the American Anthropological Association held its first independent meeting on September 24-27, 2009, at Yale University.Fifty years after the founding of the field of medical anthropology, the Society for Medical Anthropology of the American Anthropological Association held its first independent meeting on September 24-27, 2009, at Yale University in New Haven, Connecticut. The conference, Medical Anthropology at the Intersections, drew an international audience of more than 1,000 scholars.In her opening remarks, program Chair Marcia Inhorn noted that medical anthropology has been interdisciplinary since its inception. This assertion was supported at a roundtable discussion, Founding Medical Anthropology and the Society for Medical Anthropology, which featured four of the field’s founders.Asked to identify the factors that led to the development of medical anthropology, the panelists emphasized the role of changes in the practice and landscape of medicine in the late 1950s and early 1960s in the United States. According to Hazel Weidman, who helped spearhead the Society for Medical Anthropology, medical personnel sought social scientists’ guidance in the new clinical environments created by the increasing involvement of U.S. physicians in global development work and by the community-oriented approach to mental health encouraged by the Community Mental Health Act of 1963. The novel inclusion of lifestyle as a determinant of health at this time also played a role, according to Clifford Barnett. Norman Scotch, author of a 1963 review that had helped define medical anthropology as a field, noted that physicians at the time were very interested in the possible applications of the social sciences to medicine [1,2]. Joan Ablon recalled that this emphasis on application led some academic anthropologists to dismiss the medical anthropologist as a “handmaiden to the doctors.” Despite such resistance, interest in medical anthropology as a sub-field was clearly growing among anthropologists. When Weidman helped organize the first gathering of medical anthropologists at an anthropology conference in 1967, attendance was twice what was expected. Panel organizer Alan Harwood noted that the Society for Medical Anthropology transformed its newsletter into a professional journal, Medical Anthropology Quarterly, in 1983. According to Inhorn, the society has 1,300 members today.For the panelists, medical anthropology’s potential for application makes it a compelling scholarly pursuit. As Barnett stated in explaining his decision to work in anthropology: “If you know how a society works, you can change it.”     

Plant defensins: Defense,development and application

Plant defensins are small, highly stable, cysteine-rich peptides that constitute a part of the innate immune system primarily directed against fungal pathogens. Biological activities reported for plant defensins include antifungal activity, antibacterial activity, proteinase inhibitory activity and insect amylase inhibitory activity. Plant defensins have been shown to inhibit infectious diseases of humans and to induce apoptosis in a human pathogen. Transgenic plants overexpressing defensins are strongly resistant to fungal pathogens. Based on recent studies, some plant defensins are not merely toxic to microbes but also have roles in regulating plant growth and development.Key words: defensin, antifungal, antimicrobial peptide, development, innate immunityDefensins are diverse members of a large family of cationic host defence peptides (HDP), widely distributed throughout the plant and animal kingdoms.^1–3 Defensins and defensin-like peptides are functionally diverse, disrupting microbial membranes and acting as ligands for cellular recognition and signaling.⁴ In the early 1990s, the first members of the family of plant defensins were isolated from wheat and barley grains.^5,6 Those proteins were originally called γ-thionins because their size (∼5 kDa, 45 to 54 amino acids) and cysteine content (typically 4, 6 or 8 cysteine residues) were found to be similar to the thionins.⁷ Subsequent “γ-thionins” homologous proteins were indentified and cDNAs were cloned from various monocot or dicot seeds.⁸ Terras and his colleagues⁹ isolated two antifungal peptides, Rs-AFP1 and Rs-AFP2, noticed that the plant peptides'' structural and functional properties resemble those of insect and mammalian defensins, and therefore termed the family of peptides “plant defensins” in 1995. Sequences of more than 80 different plant defensin genes from different plant species were analyzed.¹⁰ A query of the UniProt database (www.uniprot.org/) currently reveals publications of 371 plant defensins available for review. The Arabidopsis genome alone contains more than 300 defensin-like (DEFL) peptides, 78% of which have a cysteine-stabilized α-helix β-sheet (CSαβ) motif common to plant and invertebrate defensins.¹¹ In addition, over 1,000 DEFL genes have been identified from plant EST projects.¹²Unlike the insect and mammalian defensins, which are mainly active against bacteria,^2,3,10,13 plant defensins, with a few exceptions, do not have antibacterial activity.¹⁴ Most plant defensins are involved in defense against a broad range of fungi.^2,3,10,15 They are not only active against phytopathogenic fungi (such as Fusarium culmorum and Botrytis cinerea), but also against baker''s yeast and human pathogenic fungi (such as Candida albicans).² Plant defensins have also been shown to inhibit the growth of roots and root hairs in Arabidopsis thaliana¹⁶ and alter growth of various tomato organs which can assume multiple functions related to defense and development.⁴     

ATG7 contributes to plant basal immunity towards fungal infection

Autophagy has an important function in cellular homeostasis. In recent years autophagy has been implicated in plant basal immunity and assigned negative (“anti-death”) and positive (“pro-death”) regulatory functions in controlling cell death programs that establish sufficient immunity to microbial infection. We recently showed that Arabidopsis mutants lacking the autophagy-associated (ATG) genes ATG5, ATG10 and ATG18a are compromised in their resistance towards infection with necrotrophic fungal pathogens but display an enhanced resistance towards biotrophic bacterial invaders. Thus, the function of autophagy as either being pro-death or anti-death depends critically on the lifestyle and infection strategy of invading microbes. Here we show that ATG7 contributes to resistance to fungal pathogens. Genetic inactivation of ATG7 results in elevated susceptibility towards the necrotrophic fungal pathogen, Alternaria brassicicola, with atg7 mutants developing spreading necrosis accompanied by production of reactive oxygen intermediates. Likewise, treatment with the fungal toxin fumonisin B1 causes spreading lesion formation in the atg7 mutant. We conclude that ATG7-dependent autophagy constitutes an “anti-death” (“pro-survival”) plant mechanism to control the containment of cell death and immunity to necrophic fungal infection.Key words: autophagy, ATG7, basal immunity, fungal resistance, arabidopsisPlants have evolved a bipartite plant immune system to cope with microbial infections. The first layer of defense relies on the recognition of pathogen-associated molecular patterns (PAMP) by pattern-recognition receptors (PAMP-triggered immunity, PTI).^1,2 To overcome this defense strategy, successful pathogens deliver so-called effector proteins into plant cells to modify host cellular processes and to suppress immune responses to enhance virulence. The presence or activities of these microbial effectors is sensed by plant resistance proteins and triggers the second layer of defense, the effector-triggered immunity (ETI).^1,2 In contrast to PTI, ETI is most often accompanied by programmed host cell death (PCD) at the site of attempted microbial invasion; however the molecular basis of this apoptosis-like hypersensitive response (HR) is largely unknown.In recent years evidence accumulated that a non-apoptotic form of cell death called autophagy is not only involved in animal PCD and innate immunity³ but is also an important component in the plant basal immune response.⁴ Generally, autophagy (auto, meaning “self” and phagy, “to eat”) is a cytoplasmic bulk degradation process in which cellular components are targeted to lysosomal or vacuolar degradation. This process is ubiquitous in eukaryotic organisms and is considered to aid cellular survival, differentiation, development and homeostasis by nutrient recycling or removal of damaged or toxic materials.^5–7     

Serine/threonine protein phosphatases: Multi-purpose enzymes in control of defense mechanisms

Depending on the threat to a plant, different pattern recognition receptors, such as receptor-like kinases, identify the stress and trigger action by appropriate defense response development.^1,2 The plant immunity system primary response to these challenges is rapid accumulation of phytohormones, such as ethylene (ET), salicylic acid (SA), and jasmonic acid (JA) and its derivatives. These phytohormones induce further signal transduction and appropriate defenses against biotic threats.^3,4 Phytohormones play crucial roles not only in the initiation of diverse downstream signaling events in plant defense but also in the activation of effective defenses through an essential process called signaling pathway crosstalk, a mechanism involved in transduction signals between two or more distinct, “linear signal transduction pathways simultaneously activated in the same cell.”⁵     

Trichomes as sensors: Detecting activity on the leaf surface

The dramatic movements of some carnivorous plants species are triggered by sensory structures derived from trichomes. While unusual plant species such as the Venus fly trap and sundews may be expected to have elaborate sensors to capture their insect prey, more modest plant species might not be expected to have similar sensory capabilities. Our recent work, however, has revealed that glandular trichomes on tomato (Solanum lycopersicum) appear to have a function similar to trigger hairs of carnivorous species, acting as “early warning” sensors. Using a combination of behavioral, molecular, and biochemical techniques, we determined that caterpillars, moths and mechanical disruption upregulate signaling molecules and defensive genes found in glandular trichomes. Importantly, we discovered that plants whose trichomes have been broken respond more vigorously when their defenses were induced. Taken together, our results suggest that glandular trichomes can act as sensors that detect activity on the leaf surface, and ready plants for herbivore attack.Key words: glandular trichome, induced responses, jasmonic acid, plant-insect interactions, sensor, Solanum lycopersicum, tomatoCertain plant species are renowned for their ability to respond to contact. The Venus fly trap (Dionaea muscipula) and sundew (Drosera) species come to mind quickly as obviously thigmotropic species. When an insect lands on these carnivorous plant species, dramatic movements ensue once the prey is detected. Some Drosera species respond to contact by bending their “tentacles” toward their trapped prey to further ensnare the victim and begin the process of digestion. These dramatic plant species have captured the attention of many scientists, including Darwin, who remarked on the “extraordinary sensitiveness of [their] glands to slight pressure” and surmised that the tentacles of sundew plants “existed primordially as glandular hairs.”¹ As is often the case, Darwin appears to have been quite right. Indeed, morphological and molecular work supports the notion that sundew tentacles and the trigger hairs of the Venus fly trap are homologous sensory structures likely derived from trichomes.^2,3Given Darwin’s appreciation of these trichome-derived sensory organs, he perhaps would not have been surprised by mounting evidence that suggests that trichomes may play even a broader sensory role for plants. We have recently found evidence that glandular trichomes can act as early detection sensors for some plant species.⁴ These trichomes can be disrupted by the footsteps of walking moths and caterpillars (and other forms of light touching), and this apparently minor plant damage leads to a state of defensive readiness that allows plants to respond to herbivory more quickly than undamaged plants. While this level of trichome-mediated detection does not result in the conspicuous responses of some carnivorous plant species, it still results in significant physiological changes that prepare plants for attack.In our recent effort, we worked with tomato (Solanum lycopersicum), using a combination of behavioral, molecular, and biochemical techniques to understand the role of trichomes in detecting activity on the leaf surface.⁴ Defense signaling has been well studied in tomato and there exists a variety of mutants whose defensive responses have been compromised. Moreover, it has been known that tomatoes have a variety of trichome types, including two types of glandular trichomes that burst upon contact with insects, releasing their cellular contents and physically impeding insects (Fig. 1).^5,6Open in a separate windowFigure 1Surface of a tomato leaf showing (A) intact rounded heads of glandular trichomes (black arrows) and (B) trichomes disrupted with a gloved hand (absence of rounded heads except for a few in the upper left corner [black arrows]). Images were captured at 36x magnification and were taken from different parts of the same leaf.To determine if plant defense pathways were induced by insect contact, we allowed three species of caterpillar (Manduca sexta, Heliothis virescens and Helicoverpa zea) and one species of moth (H. zea) to crawl over tomato leaves for ten minutes. As a positive control, we also lightly rubbed leaves with a gloved hand or a metal rod. Within time frames ranging from three to twenty-four hours all treatments, insect and otherwise, significantly induced defensive genes as measured by qRT-PCR. Using a combination of RT-PCR and in situ hybridization, we confirmed that JA-signaling and defensive genes are expressed in trichomes. A GC-MS-based technique then confirmed that JA was present in trichomes of undamaged plants and DAB staining, in combination with catalase treatment, provided evidence that hydrogren peroxide and JA are key signals mediating defensegene induction. These conclusions were further reinforced by experiments with def1 mutants, a line of tomato impaired in JA signaling, and accession LA3610, a tomato variety with reduced numbers of trichomes. Lastly, we conducted a factorial experiment both disrupting trichomes and treating tomato plants with methyl jasmonate (MeJA), which induces plant defenses and increases densities of trichomes.⁷ Results of this final experiment indicated that plants that received both treatments (i.e., MeJA and disruption) had greater defensive gene induction than plants that were only treated with MeJA or plants whose trichomes remained intact, suggesting that increases in trichomes may contribute to greater sensitivity to touch-induced responses.Taken together, our results are highly suggestive that trichomes can act as “early warning” detectors for plants. Moths seeking to lay eggs on tomato are likely to break trichomes as they explore leaves, upregulating plant defenses in anticipation of egg hatch and feeding by neonate caterpillars. Similarly, herbivores colonizing a new host plant and breaking trichomes on their way across a leaf also appear to “tip the plant off” to impending attack. Considering the drastic response of carnivorous plants to touch, perhaps it should not be surprising that trichomes can function more broadly as sensors. In an evolutionary context, it seems logical that trichomes took on this role. For many plant species, “hairy” varieties receive less herbivory,⁸ so within a population there could have been a fitness advantage in having more trichomes. Once established, this hairy phenotype could then have been refined via mutation and selection for trichome varieties that had functions adaptive for the plant, perhaps driving the evolution of glandular trichomes and their role as sensors.Granted, the generalized nature of our results would appear to indicate that plants could be “primed” by nearly any arthropod species that crosses one of their leaves. This would, of course, include natural enemies, which are capable of decreasing herbivore pressure and improving plant fitness.^9,10 However, it has been hypothesized that priming evolved due to high fitness costs associated with defensive induction following threats of only minor severity.¹¹ Priming provides an advantage by settling plants into an intermediate “ready” state that allows them to deploy strong defense responses more quickly and the fitness cost associated with being “primed” are lower than full defensive induction.¹² Presumably, fitness costs following priming due to natural enemyinduced trichome disruption would also be less than the cost incurred from a bout of unanticipated herbivory and, over the life of the plant, it would be worth the effort to prepare for attack even if the perceived risk is from a natural enemy and not a foe.Our results build on previously reported priming mechanisms that prepare plants for attack.^13,14 And they reveal an additional level of sophistication in the sensory capabilities of plants, which have already been shown to be able to detect nearby threats of herbivory and increase their defenses in response.^15,16 It seems that trichomes may have played a much wider role in shaping the nature of plant-animal interaction than previously recognized and we look forward to further work elaborating their function.     

PrP assemblies: Spotting the responsible regions in prion propagation

The “protein only” hypothesis states that the key phenomenon in prion pathogenesis is the conversion of the host protein (PrP^C) into a β-sheet enriched polymeric and pathogenic conformer (PrP^Sc). However the region of PrP bearing the information for structural transfer is still controversial. In a recent report, we highlighted the role of the C terminal part i.e., the helixes H2 and H3, using mutation approaches on recombinant PrP. The H2H3 was shown to be the minimal region necessary to reproduce the oligomerization pattern of the full-length protein. The oligomers produced from isolated H2H3 domain presented the same structural characteristics as the oligomers formed from the full-length PrP. Combining other groups'' results, this paper further discusses the relative, direct or indirect role of different PrP regions in assembly. The H2H3 region represents the core of PrP oligomers and fibrils, whereas the N terminus could explain divergences among different aggregates. Finally this review evocates the possibility to separate the domain involved in prion information transference (i.e., prion replication) from the domain bearing the cytotoxicity properties.Key words: prion, H2H3, amyloid, domain of replication, unfolding, strain, polymer, fibersTransmissible spongiform encephalopathies (TSE), fatal neurodegenerative diseases affecting humans and other mammalians, induce in most cases loss of motor control and dementia. PrP is a protein physiologically present in parts of the animal kingdom (in mammals, birds, reptiles and fishes). According to the “protein-only” hypothesis,^1,2 the key phenomenon in the pathogenesis is the conversion of the α-helix rich host-encoded PrP form (PrP^C) into a pathogenic conformer (PrP^Sc) characterized by a higher content in β-sheet and a polymeric state. The conversion to an enriched β-sheet structure is supposed to be due to the modification—induced only by a PrP^Sc-like state acting as a template- of PrP^C into the PrP^Sc conformer. This hypothesis was first proposed by Griffith in 1967³ and revisited by Lansbury et al. in 1993.⁴ The prion hypothesis has now found increasing support from experimental evidence based on the synthetic production of β-sheeted recombinant PrP which shows pathogenic properties in a wide variety of physico-chemical conditions.^5–7 However, the molecular basis of prion conversion remains unclear, especially the various structural landscape of the PrP^Sc, which is the basis of the strain phenomenon.⁸To understand the mechanisms of transfer of the structural information, two mains issues have to be addressed: (1) we need to understand which region(s) of the protein act as template for conversion and (2) what is the “pathogenic” state of this domain. In this review, we shall assume that the region bearing the infectious information for replication and the region responsible for polymerization are identical. However, the link between the propensity of a domain to form aggregates and the ability to contain the necessary information for prion replication is far from being trivial. Generally the formation of amyloid assemblies results from the aggregation of disordered peptides or in some cases from disordered regions of a folded protein.⁸ If we consider that prion replication is only supported by the globular part of PrP⁹ the currently available model involves the folded domain. Since all structural transitions need at least a partial unfolding and refolding process, pre-required structural events should be considered prior to the conversion process.     

Historical Overview on Plant Neurobiology

The review tracks the history of electrical long-distance signals from the first recordings of action potentials (APs) in sensitive Dionea and Mimosa plants at the end of the 19^th century to their re-discovery in common plants in the 1950''s, from the first intracellular recordings of APs in giant algal cells to the identification of the ionic mechanisms by voltage-clamp experiments. An important aspect is the comparison of plant and animal signals and the resulting theoretical implications that accompany the field from the first assignment of the term “action potential” to plants to recent discussions of terms like plant neurobiology.Key Words: action potentials, slow wave potentials, plant nerves, plant neurobiology, electrical signaling in plants and animailsFor a long time plants were thought to be living organisms whose limited ability to move and respond was appropriately matched by limited abilities of sensing.¹ Exceptions were made for plants with rapid and purposeful movements such as Mimosa pudica (also called the sensitive plant), Drosera (sundews), Dionea muscipula (flytraps) and tendrils of climbing plants. These sensitive plants attracted the attention of outstanding pioneer researchers like Pfeffer,^2,3 Burdon-Sanderson,^4,5 Darwin,⁶ Haberlandt^7–9 and Bose.^10–13 They found them not only to be equipped with various mechanoreceptors exceeding the sensitivity of a human finger but also to trigger action potentials (APs) that implemented these movements.The larger field of experimental electrophysiology started with Luigi Galvani''s discovery of “animal electricity” or contractions of isolated frog legs suspended between copper hooks and the iron grit of his balcony.¹⁴ It soon became clear that the role of the electric current was not to provide the energy for the contraction but to simulate a stimulus that existed naturally in the form of directionally transmitted electrical potentials. Studies by both Matteucci and Du Bois-Reymond¹⁵ recognized that wounding of nerve strands generated the appearance of a large voltage difference between the wounded (internal) and intact (external) site of nerves. This wound or injury potential was the first, crude measurement of what later became known as membrane or resting potential of nerve cells. It was also found that various stimuli reduced the size of the potential (in modern terms: they caused a depolarization), and to describe the propagating phenomenon novel terms such as action potential (AP) and action current were created (reviewed in refs. ¹⁵ and ¹⁶). Rather than relying on such indirect methods, the membrane theory of exicitation proposed by Bernstein in 1912¹⁷ made it desirable to directly measure the value of cell membrane potentials. Such progress soon became possible by the introduction of microelectrodes (KCl-filled glass micropipettes with a tip diameter small enough to be inserted into living cells) to record intracellular, i.e., the real membrane potentials (V_m). The new technique was simultaneously adopted for giant cells (axons) of cephalopods such as Loligo and Sepia¹⁸ and giant internodal cells of Charophytic green algae. In the 1930s Umrath and Osterhout^19–21 not only made the first reliable, intracellular measurements of membrane potentials in plant cells (reporting V_m values between −100 to −170 mV) but the first intracellular recordings of plant APs as well. When this technique was complemented with precise electronic amplifiers and voltage clamp circuits in the 1940s, one could measure ion currents (instead of voltages) and so directly monitor the activity of ion channels. The smart application of these methods led to a new, highly detailed understanding of the ionic species and mechanisms involved in V_m changes, especially APs.^22–27 Whereas the depolarizing spike in animal nerve cells is driven by an increased influx of Na⁺ ions, plant APs were found to involve influx of Ca²⁺ and/or efflux of Cl⁻¹ ions.The first extracellular recording of a plant AP was initiated by Charles Darwin and performed on leaves of the Venus flytrap (Dionea muscipula Ellis) by the animal physiologist Burdon-Sanderson in 1873.^4–6 Ever since APs have often been considered to fulfil comparable roles in plants and nerve-muscle preparations of animals. However, this was never a generally accepted view. While it is commonly assumed that the AP causes the trap closure, this had not been definitely shown (see refs. ²⁸ and ²⁹). Kunkel (1878) and Bose (1907, 1926) measured action spikes also in Mimosa plants where they preceded the visible folding movements of the leaflets.^{12–13,30–31} Dutrochet and Pfeffer^2–3 had already found before that interrupting vascular bundles by incision prevented the excitation from propagating beyond the cut and concluded that the stimulus must move through the vascular bundles, in particular the woody or hadrome part (in modern terms the xylem). Haberlandt⁷ cut or steam-killed the external, nonwoody part of the vascular bundles and concluded that the phloem strands were the path for the excitation, a notion which is confirmed by a majority of recent studies in Mimosa and other plant species. APs have their largest amplitude near and in the phloem and there again in the sieve cells.^{23–24,32–35} Moreover, APs can be recorded through the excised stylets of aphids known to be inserted in sieve tube elements.^36–37 Other studies found that AP-like signals propagate with equal rate and amplitude through all cells of the vascular bundle.³⁸ Starting studies with isolated vascular bundles (e.g., from the fern Adiantum), Bose found increasing amplitudes of heat-induced spikes by repeated stimulation (tetanisation) and incubation in 0.5 % solution of sodium carbonate.^10–13 Since the electrical behavior of isolated vascular strands was comparable to that of isolated frog nerves, Bose felt justified to refer to them as plant nerves.Although at the time a hardly noticed event, the discovery that normal plants such as pumpkins had propagating APs just as the esoteric “sensitive” plants was a scientific breakthrough with important consequences.^39–40,32 First, it corrected the long-held belief that normal plants are simply less sensitive and responsive than the so-called “sensitive plants” from Mimosa to Venus flytraps. Second, it led to the stimulating belief that so widely distributed electric signals must carry important messages.⁴¹ The ensuing studies made considerable progress in linking electrical signals with respiration and photosynthesis,^40–42 pollination,^43–44 phloem transport^{33,36–37,45} and the rapid, plant-wide deployment of plant defenses.^46–53The detailed visualization of nerve cells with silver salts by the Spanish zoologist S. Ramon y Cajal, the demonstrated existence of APs in Dionea and Mimosa as well as the discovery of plant mechanoreceptors in these and other plants⁹ at the end of the century was sufficient stimulation to start a search for structures that could facilitate the rapid propagation of these and other excitation signals. Researchers began to investigate easily stainable intracellular plasma strands that run across the lumen of many plant cells, and sometimes even continue over several cells for their potential role as nerve-like, excitation-conducting structures. Such strands were shown to occur in traumatized areas of many roots⁵⁴ and in insectivorous butterworts where they connect the glue-containing hair tips with the basal peptidase-producing glands of the Pinguicula leaves.^55–56 However, after investigating these claims, Haberlandt came to the conclusion that the only nerve-like structures of plants were situated the long phloem cells of the vascular bundles.^7–8 From that time on papers, lectures and textbooks reiterated statements that “plants have no nerves”.This unproductive expression ignores the work of Darwin, Haberlandt, Pfeffer and Bose together with the fact that in spite of their anatomical differences, nerve cell networks and vascular bundles share the analog function of conducting electrical signals. Similar anatomical differences have not been an obstacle to stating that both plants and animals consist of cells. The mechanistic similarity of excitations (consisting of a transient decline in cell input resistance) in plant and nerve cells was later elegantly demonstrated by the direct comparison of action potentials in Nitella and the giant axon of squids.^57–58 Today, consideration of nerve-like structures in plants involves increasingly more aspects of comparison. We know that many plants can efficiently produce electric signals in the form of action potentials and slow wave potentials (= variation potentials) and that the long-distance propagation of these signals proceeds in the vascular bundles. We also know that plants like Dionea can propagate APs with high efficiency and speed without the use of vascular bundles, probably because their cells are electrically coupled through plasmodesmata. Other analogies with neurobiology include vesicle-operated intercellular clefts in axial root tissues (the so-called plant synapses)⁵⁹ as well as the certain existence and operation of substances like neurotransmitters and synaptotagmins in plant cells (e.g., refs. ⁶⁰ and ⁶¹). The identification of the role(s) of these substances in plants will have important implications. Altogether, modern plant neurobiology might emerge as a coherent science.⁶²Electrophysiological and other studies of long-distance signals in plants and animals greatly contributed to our knowledge of the living world by revealing important similarities and crucial differences between plants and animals in an area that might directly relate to their different capacities to respond to environmental signals. Even at this stage the results are surprising. Rather than lacking electric signals, higher plants have developed more than just one signal type that is able to cover large distances. In addition to APs that occur also in animals and lower plants,⁶³ higher plants feature an additional, unique, hydraulically propagated type of electric signals called slow wave potentials.⁶⁴     

Milking the stroma in triple-negative breast cancer

Comment on: Witkiewicz AK, et al. Cell Cycle 2012; 1108–1117Investment in the post-genomic molecular dissection of breast cancer has resulted in an emphasis on prognostic and predictive markers, signatures derived to stratify the disease and the drive to generate targeted therapies. However, there remain significant challenges to individualize therapeutic targeting and improve the prognosis for the thousands of women who die each year from the heterogeneous range of breast cancers. This is particularly true for poor prognosis “triple-negative” breast cancers (TNBC), most prevalent in young and African American women, lacking the established therapeutic targets of estrogen receptor, progesterone receptor or HER2.Research has largely focused on the epithelial component of breast cancer rather than the tumor microenvironment, now recognized as a key hallmark of cancer.¹ In vitro, animal models and observations on clinical material² are now moving to consider physiological mechanisms by which stromal cells may influence breast epithelial and carcinoma cells.Witkiewicz et al.³ build on published evidence from the Lisanti group that cancer cells secrete hydrogen peroxide, initiating oxidative stress and aerobic glycolysis in tumor stroma, with L-lactate secretion from cancer-associated fibroblasts fueling oxidative mitochondrial metabolism in epithelial cancer cells: the “reverse Warburg effect.”They demonstrate stromal monocarboxylate transporter 4 (MCT4), detected by immunohistochemistry, as a functional marker of stromal hypoxia, oxidative stress, aerobic glycolysis and L-lactate efflux. High stromal MCT4 expression (but, critically, not epithelial MCT4) was associated with poor prognosis in TNBC patients. Combined high stromal MCT4 and loss of stromal caveolin-1 identify particularly poor prognostic TNBC.Thus, development of cancer may not lie solely in genetic or epigenetic epithelial changes, but with acquired functional changes in the stromal infrastructure of the breast. This supports the concept of epithelial malignant changes consequent with ecological and evolutionary opportunity.⁴ The “parasitic” character of tumor cells feeding off stromal cells highlights the need to seriously consider both ecological and biophysical concepts.⁵ We need to think beyond “intraspecific” competition among clonal subpopulations in the tumor and to consider tumor and stromal cells as distinct populations in a cancer ecosystem, with a range of “interspecific” competitive, exploitative and opportunistic interactions. Furthermore, the reverse Warburg effect relies on the inefficient diffusion of nutrients from stromal cells to tumor cells in a complex three-dimensional space. The extracellular space is brought to the foreground, and physical properties of molecular transport in this space may have as much impact on tumor growth as intricate cellular processes. The importance of the spatial arena is also apparent when contrasting the reverse Warburg effect with angiogenesis. In the former, tumor cells are exploiting their local environment, which will presumably be of limited yield, whereas angiogenesis taps the nutrients of the entire organism—­an effectively infinite reservoir for a growing tumor. In the reverse Warburg effect, a balance of ecological and biophysical factors underpins the sustainability of this mode of cancer nutrition. A two-compartment model coupling oxidative epithelial cells with glycolytic fibroblasts reflects increased expression of hypoxia-associated genes as a component part of prognostic stromal signatures.⁶ Further evidence of stromal/epithelial interaction comes from evidence that the effects of radiation on normal breast epithelium in vivo is at least partially dependent on the stromal context.⁷Manipulation of the tumor microenvironment to promote an anticancer phenotype challenges the cancer treatment paradigm. The long-established antidiabetes biguanide drugs offer a low-toxicity opportunity to disrupt the reverse Warburg effect. Metformin may target the cancer mitochondria³ and phenformin induce stromal sclerosis, at least in a breast cancer xenograft model,⁸ in addition to in vivo AMPK pathway and insulin-mediated systemic effects of metformin in women with breast cancer.⁹ The reverse Warburg effect challenges our therapeutic focus on breast cancer epithelium. Stromal MCT4 expression with caveolin-1 loss identifies poor prognostic TNBC patients and emphasizes the roles of the tumor microenvironment and ecological interactions between distinct populations of cells. The challenges now revolve around therapeutic manipulation of the stroma/epithelial interaction and the extracellular space, and testing these concepts in pre-invasive and metastatic settings where stromal changes may provide tissue niches of evolutionary opportunity for malignant cells.     

KSR Int'l Co. v. Teleflex, Inc.: no obvious changes for the biotechnology market

With the advent of molecular biology, genomics, and proteomics, the intersection between science and law has become increasingly significant. In addition to the ethical and legal concerns surrounding the collection, storage, and use of genomic data, patent disputes for new biotechnologies are quickly becoming part of mainstream business discussions. Under current patent law, new technologies cannot be patented if they are “obvious” changes to an existing patent. The definition of “obvious,” therefore, has a huge impact on determining whether a patent is granted. For example, are modifications to microarray protocols, popular in diagnostic medicine, considered “obvious” improvements of previous products? Also, inventions that are readily apparent now may not have been obvious when discovered. Polymerase chain reaction, or PCR, is now a common component of every biologist’s toolbox and seems like an obvious invention, though it clearly was not in 1983. Thus, there is also a temporal component that complicates the interpretation of an invention’s obviousness. The following article discusses how a recent Supreme Court decision has altered the definition of “obviousness” in patent disputes. By examining how the obviousness standard has changed, the article illuminates how legal definitions that seem wholly unrelated to biology or medicine could still potentially have enormous effects on these fieldsJust what is obvious or not is a question that has provoked substantial litigation in the Federal Circuit, the appellate court with special jurisdiction over patent law disputes. Under U.S. patent law, an inventor may not obtain a patent, which protects his invention from infringement by others, if the differences between the subject matter sought to be patented and the prior art are such that “the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill” in the patent’s subject matter area [1]. However, what was “obvious” at the time of invention to a person of ordinary skill is hardly clear and is, in effect, a legal fiction designed to approximate objectivity. As illustrated by Chief Justice John Roberts of the Supreme Court in a moment of levity, “Who do you get to ... tell you something’s not obvious … the least insightful person you can find?” [2] Despite the apparent objectivity provided by a “person of ordinary skill” obviousness standard, the difficulty lies in that such a standard is still susceptible to multiple interpretations, depending on the point of view and knowledge ascribed to the “ordinary person.” As such, how obviousness is defined and interpreted by the courts will have important implications on biotechnology patents and the biotechnology business.The issue of obviousness arose in April 2007 when the Supreme Court handed down its decision in KSR Int’l Co. v. Teleflex, Inc. [3] The facts of the case were anything but glamorous; in the suit, Teleflex, a manufacturer of adjustable pedal systems for automobiles, sued KSR, its rival, for infringement of its patent, which “describe[d] a mechanism for combining an electronic sensor with an adjustable automobile pedal so that the pedal’s position can be transmitted to a computer that controls the throttle in the vehicle’s engine.” [4] Teleflex believed that KSR’s new pedal design was too similar to its own patented design and therefore infringed upon it [5]. In defense, KSR argued that Teleflex’s patent was merely the obvious combination of two pre-existing elements and, thus, the patent, upon which Teleflex’s infringement claim was based, was invalid.Patent law relies on the concept of obviousness to distinguish whether new inventions are worthy of being protected by a patent. If a new invention is too obvious, it is not granted a patent and is therefore not a legally protected property interest. However, if an invention is deemed not obvious and has met the other patentability requirements, a patent will be granted, thereby conferring exclusive use of the invention to the patent holder. This exclusive right prohibits others from making, using, selling, offering to sell, or importing into the United States the patented invention [6]. Essentially, the definition of obviousness sets the balance between rewarding new inventions with exclusive property rights and respecting old inventions by not treating minor variations of existing patents as new patents. In this manner, the law seeks to provide economic incentives for the creation of new inventions by ensuring that the property right conferred by the patent will be protected against insignificant variations. The importance of where the line for obviousness is drawn and how clearly it is drawn is especially important in the biotechnology industry. Studies have shown that the development of a new pharmaceutical therapy can take up to 14 years with costs exceeding $800 million [7]. Such an enormous investment of time and money would not be practical if it did not predictably result in a legally enforceable property right.The standard for what constitutes a patentable discovery has evolved over the last 150 years. In 1851, the Supreme Court held in Hotchkiss v. Greenwood that a patentable discovery required a level of ingenuity above that possessed by an ordinary person [8]. Lower courts treated the Hotchkiss standard as a subjective standard, whereby courts sought to determine “what constitute[d] an invention” [9] and a “flash of creative genius” [10]. However, the attempts at imposing the Hotchkiss standard proved unworkable, and in 1952, Congress overrode the case law with the Patent Act, “mandat[ing] that patentability be governed by an objective nonobviousness standard.” [11] This new statutory standard moved the courts away from subjective determinations and toward a more workable, objective obviousness standard.While the Patent Act laid the foundation for the current obviousness standard, the Supreme Court in Graham v. John Deere Co. interpreted the statutory language in an attempt to provide greater clarity as to what exactly “obvious” meant [12]. The Supreme Court determined that the objective analysis would require “the scope and content of the prior art ... to be determined; differences between the prior art and the claims at issue ... to be ascertained; and the level of ordinary skill in the pertinent art resolved.” [13] In addition to analysis under this three-part framework, the Supreme Court called for several secondary considerations to be weighed, including “commercial success, long felt but unresolved needs, [and the] failure of others [to solve the problem addressed].” [13]Unsurprisingly, lower courts were unsatisfied with the Supreme Court’s attempts to clarify the obviousness standard and sought to provide “more uniformity and consistency” to their evaluation of obviousness than the Supreme Court’s jumble of factors provided [14]. In search of consistency, the Federal Circuit created the “teaching, suggestion, or motivation” test (TSM test) “under which a patent is only proved obvious if ‘some motivation or suggestion to combine prior art teachings’ can be found in the prior art, the nature of the problem, or the knowledge of a person having ordinary skill in the art.” [14] Through implementation of the TSM test, the Federal Circuit sought to maintain the flexibility envisioned by the Supreme Court in Graham, while at the same time providing more certainty and predictability to obviousness determinations.The issue before the Supreme Court in KSR Int’l Co. v. Teleflex, Inc. was whether the Federal Circuit’s elaboration on the statutory language of the Patent Act, the TSM test, was consistent with the terms of the Patent Act itself and the Supreme Court’s own analysis in Graham. The Supreme Court determined that while the TSM test was, on its terms, consistent with the framework set out in Graham, the rigid manner in which the Federal Circuit had taken to applying that standard was inconsistent with the flexible approach established by Graham [15]. More generally, it appears the Supreme Court was mainly interested in restoring a more rounded, thorough inquiry to the evaluation of obviousness: “Graham set forth a broad inquiry and invited courts, where appropriate, to look at any secondary considerations that would prove instructive.” [16] As stated by the Supreme Court, “[r]igid preventative rules that deny factfinders recourse to common sense, however, are neither necessary under our case law nor consistent with it.” [17] As such, the Supreme Court reversed the findings of the Federal Circuit, which had found the Teleflex patent valid, and remanded the case back to the lower court with directions to analyze, without rigid adherence to the TSM test, whether the Teleflex patent was obvious [18].The Supreme Court’s ruling in KSR Int’l Co. v. Teleflex, Inc. that the Federal Circuit apply its TSM test less rigidly may have implications for those seeking biotechnology patents in the future. As discussed above, the large investments necessary to develop a marketable biotechnology product demand that entrepreneurs making those investments be reasonably assured that they can predict any future legal hurdles in patenting their invention and in ultimately protecting their patent. As explained by the Biotechnology Industry Organization in its amicus curiae brief in KSR Int’l Co. v. Teleflex, Inc., “[i]nvestment thus is predicated on an expected return on investment in the form of products or services that are protected by patents whose validity can be fairly determined.” [19] Therefore, the Supreme Court’s insistence that the Federal Circuit no longer rigidly rely on the TSM test could increase uncertainty in the grant of future patents. However, the Supreme Court’s refusal to completely dismiss the TSM test, while in fact endorsing its continued use, albeit on a less rigid basis, has to be viewed as a profound victory for an industry with a significant stake in maintaining the status quo. Moreover, it is unclear how much the Supreme Court’s holding in KSR Int’l Co. v. Teleflex, Inc. will truly change the legal analysis of the lower courts, given the evidence that lower courts already were independently shifting away from rigid adherence to the TSM test before the Supreme Court’s ruling [20].More importantly, several aspects of the Supreme Court’s reasoning in KSR Int’l Co. v. Teleflex, Inc. seem to directly address relevant concerns of the biotechnology market in favorable ways. First, the Supreme Court made clear that though a product is the result of a combination of elements that were “obvious to try,” it is not necessarily “obvious” under the Patent Act. Retaining the possibility that “obvious to try” inventions still may be patentable is extremely important to the biotechnology industry in particular because “many patentable inventions in biotechnology spring from known components and methodologies found in [the] prior art.” [21] Rather than foreclosing all “obvious to try” inventions as being obvious, and therefore not patentable, the Supreme Court instead explained that where there is “a design need or market pressure to solve a problem and there are a finite number of identified, predictable solutions,” it is more likely that a person of ordinary skill would find it obvious to pursue “known options.” [22] Thus, the proper inquiry, as stated by the Supreme Court, is “whether the improvement is more than the predictable use of prior art elements according to their established functions.” [23] While this reasoning may prevent some “obvious to try” inventions from being patented, it is unlikely to have a substantial effect on inventions in the biotechnology market because “most advances in biotechnology are only won through great effort and expense, and with only a low probability of success in achieving the claimed invention at the outset.” [24] In other words, it would be hard to characterize the use of prior art in the biotechnology context as predictable based on the inherent unpredictability of obtaining favorable results. As such, most biotechnology inventions would presumably fall outside the Supreme Court’s “obvious to try” reasoning due to the very nature of the industry, meaning they would remain patentable under the Supreme Court’s KSR Int’l Co. v. Teleflex, Inc. decision.Second, the Supreme Court recognized the “distortion caused by hindsight bias” and the importance of avoiding “arguments reliant upon ex post reasoning,” though it lessened the Federal Circuit’s rigid protection against hindsight bias [24]. Hindsight bias requires that obviousness be viewed at the time the invention was made, because what may seem revolutionary at the time of invention may, upon the passage of time, seem “obvious.” Cognizance of hindsight bias is crucial for biotechnology patents because “there often is a long ‘passage of time between patent application filing and litigation with biotechnology inventions [that] can exacerbate the problem’ of hindsight bias.” [25] The problem is further exacerbated by the “significantly longer durations of commercial utility” biotechnology inventions enjoy as compared to those in other fields [25]. The more time between the filing of a patent and the subsequent litigation over its validity, the greater the risk that “reliable accounts of [the] context” in which the discovery is made will no longer exist [26]. As such, inventions that were not obvious when they were created will be inescapably colored by the passage of time and by new knowledge and discoveries; the likelihood of this occurrence is higher the further removed the litigation is from the patent filing date. Once again, however, it seems clear that despite the Supreme Court’s abandonment of the TSM test’s rigidity, strong protections against hindsight bias still were emphasized in the Supreme Court’s KSR Int’l Co. v. Teleflex, Inc. decision. In fact, lower courts applying KSR Int’l Co. v. Teleflex, Inc. acknowledge they are “cautious” to avoid “using hindsight” in biotechnology obviousness determinations [27].Finally, the Supreme Court seems to believe that the imposition of a more flexible approach will be more likely to benefit markets not directly at issue in KSR Int’l Co. v. Teleflex, Inc. The Supreme Court asserted, “[t]he diversity of inventive pursuits and of modern technology counsels against limiting the analysis” to the rigid TSM test of the Federal Circuit [28]. This language suggests that the Supreme Court expects lower courts to take into consideration the special considerations facing unique markets, such as the biotechnology market. As such, the specific concerns of the biotechnology market discussed above may receive more attention under the flexible framework asserted by the Supreme Court in KSR Int’l Co. v. Teleflex, Inc.Leading up to the oral argument in KSR Int’l Co. v. Teleflex, Inc., there was widespread speculation that the case could result in a watershed moment, significantly altering the definition of obviousness in patent law. For many, including those in the biotechnology industry, there was ample reason to be concerned. Any change in the definition of obviousness would effectively shift property rights from new patent holders to old, or vice versa. However, the Supreme Court acted with restraint. While the decision purports to make substantial changes by doing away with the Federal Circuit’s TSM test, the opinion seems more like a mild-mannered rebuke of lower courts that had become too complacent in the implementation of their beloved test. If anything, the Supreme Court’s insistence on a more flexible formula is simply a call for lower courts to employ common sense, in addition to considering the factors from Graham and the TSM test. Accordingly, the Supreme Court’s opinion in KSR Int’l Co. v. Teleflex, Inc. is unlikely to have a pronounced effect on the biotechnology market, despite the widespread concern generated before the actual decision was handed down.     

Analysis of the Fine-Scale Population Structure of “Candidatus Accumulibacter phosphatis” in Enhanced Biological Phosphorus Removal Sludge,Using Fluorescence In Situ Hybridization and Flow Cytometric Sorting

To investigate the fine-scale diversity of the polyphosphate-accumulating organisms (PAO) “Candidatus Accumulibacter phosphatis” (henceforth referred to as “Ca. Accumulibacter”), two laboratory-scale sequencing batch reactors (SBRs) for enhanced biological phosphorus removal (EBPR) were operated with sodium acetate as the sole carbon source. During SBR operations, activated sludge always contained morphologically different “Ca. Accumulibacter” strains showing typical EBPR performances, as confirmed by the combined technique of fluorescence in situ hybridization (FISH) and microautoradiography (MAR). Fragments of “Ca. Accumulibacter” 16S rRNA genes were retrieved from the sludge. Phylogenetic analyses together with sequences from the GenBank database showed that “Ca. Accumulibacter” 16S rRNA genes of the EBPR sludge were clearly differentiated into four “Ca. Accumulibacter” clades, Acc-SG1, Acc-SG2, Acc-SG3, and Acc-SG4. The specific FISH probes Acc444, Acc184, Acc72, and Acc119 targeting these clades and some helpers and competitors were designed by using the ARB program. Microbial characterization by FISH analysis using specific FISH probes also clearly indicated the presence of different “Ca. Accumulibacter” cell morphotypes. Especially, members of Acc-SG3, targeted by probe Acc72, were coccobacillus-shaped cells with a size of approximately 2 to 3 μm, while members of Acc-SG1, Acc-SG2, and Acc-SG4, targeted by Acc444, Acc184, and Acc119, respectively, were coccus-shaped cells approximately 1 μm in size. Subsequently, cells targeted by each FISH probe were sorted by use of a flow cytometer, and their polyphosphate kinase 1 (ppk1) gene homologs were amplified by using a ppk1-specific PCR primer set for “Ca. Accumulibacter.” The phylogenetic tree based on sequences of the ppk1 gene homologs was basically congruent with that of the 16S rRNA genes, but members of Acc-SG3 with a distinct morphology comprised two different ppk1 genes. These results suggest that “Ca. Accumulibacter” strains may be diverse physiologically and ecologically and represent distinct populations with genetically determined adaptations in EBPR systems.Enhanced biological phosphorus removal (EBPR) has been applied in many wastewater treatment plants to reduce the phosphorus that causes eutrophication in surface waters. EBPR employs polyphosphate-accumulating organisms (PAOs), which are enriched through alternating aerobic-anaerobic cycles (34). Since PAOs are essential for an understanding of EBPR, many candidates have been proposed as potential PAOs, such as Acinetobacter spp. (11), Tetrasphaera spp. (31), Microlunatus phosphovorus (36), Lampropedia spp. (40), and Gram-positive Actinobacteria (24). However, those organisms do not exhibit all of the characteristics of the EBPR biochemistry model. Recently developed culture-independent approaches such as PCR-clone libraries, fluorescence in situ hybridization (FISH), and microautoradiography (MAR) have highlighted an uncultured Rhodocyclus-related bacterium, “Candidatus Accumulibacter phosphatis” (henceforth referred to as “Ca. Accumulibacter”), as one of the most important PAO candidates (2, 5, 16, 22, 23, 27, 28, 47).Numerous studies have sought to investigate uncultured “Ca. Accumulibacter” and have shown the presence of genetically and physiologically different members with a global geographic distribution (3, 9, 22, 27, 39). For example, Kong et al. (22) identified two morphologically different “Ca. Accumulibacter” cells of small cocci and large coccobacilli labeled with PAOmix (PAO462, PAO651, and PAO846) in laboratory-scale EBPR reactors. Additional results showing phenotypic and morphological diversities of “Ca. Accumulibacter” cells also existed with respect to the different roles of denitrifying PAO (DPAO) in the EBPR process (3, 9, 23). Carvalho et al. (3) detected two different morphotypes of “Ca. Accumulibacter” with different nitrate reduction capabilities. The presence of other “Ca. Accumulibacter” strains with 15% genome sequence divergence from the dominant strains in metagenomic analyses is likely to explain these morphological and phenotypic differences (12). McMahon et al. (33) suggested the use of the polyphosphate kinase (ppk) gene, which is involved in the production of polyphosphate, for a finer elucidation of “Ca. Accumulibacter” diversity. He et al. (15) grouped “Ca. Accumulibacter” strains into five distinct clades, designated clades I, IIA, IIB, IIC, and IID, using ppk gene sequence information. Flowers and colleagues (9) previously reported that “Ca. Accumulibacter” cells of clade IA had nitrate reduction activity with phosphorus uptake but that “Ca. Accumulibacter” cells of clade IIA did not.FISH-fluorescence activated cell sorting (FACS) techniques have been used for the separation of specific microbial cells from complex microbial consortia and their metabolic gene analysis (14, 46). For example, Miyauchi et al. (35) sorted PAOmix probe-labeled “Ca. Accumulibacter” cells from EBPR sludge and analyzed their nitrite reductase gene (nirS) diversity. In the current study, we found that four different “Ca. Accumulibacter” clades (Acc-SG1, Acc-SG2, Acc-SG3, and Acc-SG4) were present in the EBPR sludge of laboratory-scale reactors supplied with acetate as the sole carbon source. We analyzed their morphological characteristics and ppk gene sequence information using a suite of FISH and FACS approaches and linked fine-scale phylogenetic diversities of “Ca. Accumulibacter” strains with their morphological characteristics and metabolic genes. This study will be useful for further genetic and physiological studies of different “Ca. Accumulibacter” clades.     

Rapid stomatal closure triggered by a short ozone pulse is followed by reopening to overshooting values

Stomatal pores, surrounded by the pairs of guard cells, regulate plant gas exchange. Correct stomatal regulation is crucial for plant survival under various stress conditions. We have recently utilized the air pollutant ozone (O₃) to study stomatal signaling and showed that application of O₃ induces rapid decrease in stomatal conductance. Here we have addressed the recovery of stomatal conductance and show that after exposures of plants to high O₃ pulses stomatal conductance recovered faster, reaching higher, “overshooting” values than were the pre-exposure values. We propose the hypothetical mechanism for this phenomenon and discuss it in the frames of current stomatal signaling models.Key words: ozone, stomata, signaling, Arabidopsis, overshooting, guard cells, stressRapid progress in understanding structural and molecular mechanisms of the core abscisic acid (ABA) signaling pathway and subsequent stomatal closure (reviewed in ref. ¹) has been achieved by using a variety of mostly in vitro technologies and approaches. Data on early induction of stomatal response by a brief ABA pulse in vivo is almost absent, largely due to difficulties in rapid removal of ABA from intact guard cells. Application of O₃, an air pollutant efficiently utilized to study stomatal signaling,^2–4 lacks this disadvantage and allows monitoring stomatal responses to brief, clean-cut, strictly dosed pulses of this powerful oxidant in planta. Application of O₃ for 1 min to intact Arabidopsis rosette triggered a Rapid Transient Decrease (RTD) in stomatal conductance which, after lasting for 8–10 min, was followed by a 3–4 times slower recovery.³ The entire RTD, lasting for up to 40–50 min, is a conserved response in plants; to date it is found to be present in about 90 Arabidopsis ecotypes/mutants³ and also in tobacco and birch (unpublished results). Absence of RTD in protein phosphatase ABI1 and ABI2 mutants (abi1-1 and abi2-1) which are unable to form complex with PYR/PYL ABA receptors, in protein kinase OST1 and in guard cell plasma membrane anion channel SLAC1 mutants, indicates that O₃-triggered signal propagates through the same phosphatase/kinase pair as does the signal triggered by ABA.³ Results of mostly proteomic, pharmacological and electrophysiological studies allow to suggest that the most likely reason for the rapid stomatal closure during RTD is the ABI1, ABI2 and OST1 mediated alterations in a battery of plasma membrane ion channels, including the outward-rectifying anion channel SLAC1 and the depolarization-activated K⁺ channel GORK1 which after their sequential activation result in efflux of osmotica, turgor loss and stomatal closure.Physiological background of the recovery during RTD which takes place also under continuous exposure to ozone² is less understood. To study this process further we exposed whole rosettes of intact 22–25 day old Arabidopsis plants to different O₃ concentrations for 3 min as described earlier³ and observed that after exposures to high concentration O₃ pulses stomatal conductance recovered faster and reached higher values than were the preexposure values. We term this phenomenon “overshooting”.Ozone concentration of 70 nl l⁻¹ did not induce RTD (Fig. 1A). At higher concentrations O₃ induced intense decrease in stomatal conductance within 4–6 min after application. This was followed by rapid stoppage of the closure, a brief transition period and a sluggish, almost linear recovery where the pre-exposure value of stomatal conductance was reached about 30 min after the onset of O₃ (Fig. 1A). The rates and extents of the O₃-induced stomatal closure, as well as rates of reopening were concentration dependent. Continuation of the linear increase in stomatal conductance after reaching the pre-exposure value resulted in almost two-fold higher values at 50 min after the onset of 385 nl l⁻¹ of O₃. Overshootings were dependent on ozone concentration (Fig. 1B) and on the extent of the initial decrease in stomatal conductance (Fig. 1C). Both dependencies were exponential indicating a presence of threshold at 150–200 nl l⁻¹ of O₃ and at 20% of initial O₃-induced decrease in stomatal conductance, respectively.Open in a separate windowFigure 1Ozone-triggered rapid decrease in stomatal conductance is followed by recovery to higher “overshooting” values. (A) Typical asymmetric time patterns of stomatal conductance after exposure of 22–25 day old Arabidopsis plant leaf rosettes to different concentrations of ozone as described in Kollist et al.² In (B and C) O₃-induced “overshooting” is plotted against O₃ concentration and O₃-induced decrease in stomatal conductance, respectively.What could be the reason and mechanistic explanation for described O₃-induced “overshooting” in stomatal conductance? The protein kinase OST1 is required for induction of rapid closure phase of the O₃-triggered RTD.³ Besides phosphorylating SLAC1,^3,5 OST1 has been shown to phosphorylate also the inward-rectifying K⁺ channel KAT1 resulting in its inhibition.⁶ Inhibition of K⁺ uptake, which allows faster membrane depolarization and stomatal closure, has been shown to occur under various stresses.⁷ Presumably, H⁺-ATPase activity and proton pumping, tightly coupled to K⁺ uptake via channel energization⁸ are also suppressed by O₃. It has been shown that in depolarized guard cell, plasma membrane proton pumping may precede volume and turgor increase.⁹ We speculate that in the O₃-triggered, SLAC1- and GORK-mediated stomatal closure, when ion efflux and turgor loss proceed at high rates, reactivation of H⁺-ATPase and proton pumping and associated recovery of K⁺ uptake are induced to avoid guard cell plasmolysis.¹⁰ Guard cells begin to regain turgor and stomata reopen. At the same time outward-rectifying ion channels are transiently locked (inactivated) as stomata become completely insensitive to repeated O₃-pulses during recovery phase.³ This interpretation is supported by our observation that the recovery in stomatal opening is heavily suppressed in kincless mutant³ where the inward rectifying K⁺ current is abolished.¹¹ In addition, peak densities of inward K⁺ currents (2–4 µA/cm² membrane⁹) are shown to be much lower than those for outward anion and K⁺ currents (17–20 µA/cm).^2,8,12,13 This could be a reason why stomatal reopening is much slower than the initial O₃-induced closure. Our findings (Fig. 1) suggest that the faster and deeper the O₃-triggered turgor loss, the faster and extensive is its recovery. The “overshootings” suggest plasma membrane hyperpolarization and predict a viable oscillation-like stomatal behavior where the system tends to restore the initial equilibrium. Longer experiments are needed to address whether such an oscillating response exists in Arabidopsis elicited by O₃.Taken together, our data suggest the presence of a “security” mechanism in plant guard cells which avoids the excessive dehydration and precipitous turgor loss by reswitching the reaccumulation of osmotica ultimately leading to stomatal opening. Molecular mechanism(s) linking feedback from low turgor to activation of plasma membrane proton pumping and subsequent ion uptake are obscure. Irrespective of mechanism(s), our data indicate that stomata tend to recover from stress the faster the stronger has been the perturbation at its onset. Undoubtedly, rapid O₃-induced transient decrease in stomatal conductance is one of countless expressions of the Le Chatelier''s principle having numerous wordings like: “any change in status quo prompts an opposing reaction in the responding system,” or paraphrased on the basis of our results—the stronger the stimulus (O₃ concentration) the stronger the response (“overshooting”).     

2009 Society for Medical Anthropology Conference: Global Public Health through the Eyes of Medical Anthropologist Didier Fassin

At the 2009 Society for Medical Anthropology Conference at Yale University, anthropologist Didier Fassin discussed social inequality and the politicization of health in the context of global public health.U.S. Rep. Joe Wilson shouted, “You lie!” during President Obama’s denial that the proposed health care reform bill would cover illegal immigrants, and anthropologist Didier Fassin used that antagonistic stance toward what the 1978 Declaration of Alma-Ata [1] had called a fundamental human right to best illustrate the issues of social inequality and the politicization of health.Global public health was one focus of the 2009 Society for Medical Anthropology Conference at Yale University in September. Since its inception in 1948, the World Health Organization (WHO) has striven to provide health assistance to the world population, especially those in developing countries. But Fassin, professor of social science at the Institute for Advanced Study at Princeton, professor of sociology at the Université de Paris, Nord, and director of studies in political and moral anthropology at the Ecole des Hautes Études en Sciences Sociales, argued that the concept of global health, albeit well-meaning, is problematic. Its utopian nature is clearly apparent in the rhetoric of politicians, he said, adding that health as a gift of nature, a common good, and the core of the WHO, quickly becomes an object of politics and the coverage in times of sickness of a select few is akin to entitlement and privilege.The present age of globalization certainly makes health threats such as epidemics a threat to all, and nations are in it together to take preventive measures or put up a concerted fight. However, threats like bioterrorism or predicted consequences of global warming such as population migration may be viewed, particularly by Western countries, as security issues that menace national interests and state sovereignties. The consequence being that new policies are implemented that may directly or indirectly affect the rest of the world population.And then there is the issue of humanitarian intervention, which Fassin refers to as “politics of life” [2]. How can we view humanitarianism with the eye of a cynic when it is, in essence, the effort to demonstrate the very best of our nature? Yet the transformation of some humanitarian interventions into military operations and the decision to intervene (Iraq, Kosovo, Bosnia) or not (Rwanda, Ethiopia, Cambodia), politicize this notion. Additionally, Fassin believes that the key nation-states integrate their own cultural and political biases during interventions in troubled regions.Nowhere is this subjectivity more apparent than in the image of suffering as depicted by psychologists and psychiatrists working for non-government organizations (NGOs). NGOs compile testimonies of traumatized people in war and conflict zones, but their subjective narratives enmeshed in the diagnosis reports are increasingly supplanting faithful witness accounts. Fassin sees this trauma as “political expression of the world” [3]. The experts, in trying to raise awareness on issues that need immediate attention, may dramatize certain situations or get emotionally involved during their missions and take sides. They become the new voice of the conflict and their efforts may throw the victims into a state of confusion.It’s no surprise then that some nations view with distrust Western practices and their portrayal of aggressors and victims [4]. In 2000, Thabo Mbeki, then president of South Africa, convened an advisory panel that aimed to collect scientific data to prove that HIV does not cause AIDS. In return, he received the Durban Declaration with the signatures of more than 5,000 scientists and doctors who unilaterally declared the opposite to be scientifically true.Fassin brings up the abovementioned issues in order to shift attention to the difficulties that face our common efforts for better health services. It is truly challenging for Western leaders to mend the rift between their political agendas and accessible health for all, and as long as that continues to be the case, health care will elude millions.