Wetland plant decomposition under different nutrient conditions: what is more important, litter quality or site quality?

Plants in nutrient poor environments are often characterized by high nutrient resorption resulting in poor litter quality and, consequently, slow decomposition. We used oligotrophic, P-limited herbaceous wetlands of northern Belize as a model system, on which to document and explain how changes in nutrient content along a salinity gradient affect decomposition rates of macrophytes. In 2001 we established a nutrient addition experiment (P, N, and N&P) in 15 marshes of a wide range of water conductivities (200–6000 μS), dominated by Eleocharis spp. To determine what is more important for decomposition, the initial litter quality, or site differences, we used reciprocal litter placement and cellulose decomposition assay in a combined “site quality” and “litter quality” experiment. Our prediction of the positive effects of P-enrichment on decomposition rate due to both the quality of litter and the site was confirmed. The site effect was stronger than the litter quality although both were highly significant. Strong site quality effect was apparently the result of more active decomposer community in P-enriched plots as supported by finding of higher microbial biomass in litter decomposing there. The strong effect of site quality on decomposition was further confirmed by the cellulose assay. The cellulose decomposition was significantly slower at high salinity sites indicating lower decomposer microbial activity. Litter nutrient N and P content and nutrient ratios were well correlated with decomposition with the best fit found for log C/P. At C/P mass ratio of >4000 decomposition processes were extremely slow. We hypothesize that in a long run, the increased decomposition will compensate the increase in primary production resulting from increased nutrient loading and there will be no differences in accumulation of organic material between the controls and nutrient enriched plots.     

Competitive reversals inside ecological reserves: the role of external habitat degradation

 Habitat degradation is the slow – and often subtle – deterioration in habitat quality that accompanies human activities through increases in road density, pesticide use, hunting pressure, etc. Such degradation is of particular concern in fragmented habitats where economic or jurisdictional boundaries rather than ecological ones determine the level of exploitation adjoining habitat patches endure. To examine the consequences habitat degradation might have on species interactions, we posited a patch of pristine habitat surrounded by “matrix” habitat whose degradation level was variable. Using a coupled pair of diffusive Lotka–Volterra competition equations with Robin (mixed) boundary conditions, we modeled the dynamics of two competing species inhabiting the pristine patch and incorporated matrix degradation through a tunable “hostility” parameter representing species’ mortality rates in the matrix. We found that the numerical range of competition coefficients over which one species is the competitive dominant and the other inferior may grow or shrink as matrix quality deteriorates. In some cases, degradation of the exterior habitat would bring about a complete competitive reversal inside the preserve. This result, wherein a formerly inferior species supplants a formerly dominant one – even inside the “protected” remnant patch itself – has policy implications for both nature reserve design and management of human activities outside park boundaries. Received: 30 April 1997     

Cytotoxic and fluorescent assays for thymocyte subpopulations differing in surface thy-1 level

A number of analytical techniques for distinguishing and separating the “high θ” and “low θ” subpopulations of mouse thymocytes have been compared. A differential cytotoxic assay was compared to a quantitative immunofluorescent assay on individual cells using flow cytofluorometry and cell sorting. Conventional anti-Thy-1 antisera were compared with a monoclonal IgM anti-Thy-1. The monoclonal reagent greatly improved both types of assay, eliminated a number of artifacts and allowed either procedure to be used to give a clear distinction, based on Thy-1 level, between the two subpopulations. The distribution of Thy-1 on thymocytes is bimodal, rather than continuous. These separate “high θ” and “low θ” categories each includes a population of dividing cells.     

Assessment of Gene Flow from Genetically Modified Anthracnose-Resistant Chili Pepper (Capsicum annuum L.) to a Conventional Crop

We conducted a 2-year field assessment of the gene flow from genetically modified (GM) chili pepper (Capsicum annuum L.), containing the PepEST (pepper esterase) gene, to a non-GM control line “WT512” and two commercial hybrid cultivars, “Manidda” and “Cheongpung Myeongwol (CM).” After seeds were collected from the pollen-recipient non-GM plants, hybrids between them and the GM peppers were screened by a hygromycin assay. PCR with the targeting hpt gene was performed to confirm the presence of transgenes in hygromycin-resistant seedlings. Out of 7,071 “WT512” seeds and 6,854 “Manidda” seeds collected in 2006, eight and 12 hybrids, respectively, were detected. In 2007, 33 hybrids from 3,456 “WT512” seeds and 50 hybrids from 3,457 “CM” seeds were found. The highest frequency of gene flow, 6.19%, was observed in that 2007 trial. These results suggest that a limited isolation distance would be sufficient to prevent gene flow from GM to conventionally bred chili peppers.     

FGF2 and dexamethasone increase the production of hyaluronan in two-dimensional culture of elastic cartilage-derived cells: in vitro analyses and in vivo cartilage formation

Elastic cartilage-derived cells cultured two-dimensionally with FGF2 and corticosteroid produce gel-type masses that become mature cartilage when injected into a subcutaneous pocket. This unique method has previously been clinically applied for treatments of nasal augmentation. However, the components of the gel-type mass and the mechanism of its synthesis remain unknown. Here, we have investigated the components of the gel-type mass produced by elastic cartilage-derived cells, and whether this gel-type mass can be produced by using other cell sources or other media. Human elastic cartilage-derived cells from auricular cartilage, hyaline cartilage-derived cells from articular cartilage, and mesenchymal stem cells from synovium were cultured in three media: “redifferentiation medium” containing FGF2 and dexamethasone; “chondrogenic medium” containing bone morphogenetic protein-2, transforming growth factor-β3, and dexamethasone specific for in vitro chondrogenesis of mesenchymal stem cells; control medium. The elastic cartilage-derived cells cultured in redifferentiation medium produced a gelatinous matrix positive for Alcian blue. During culture, the amount of chondroitin 4-sulfate, chondroitin 6-sulfate, and especially hyaluronan increased. However, the expression of RNAs for most chondrogenic genes did not increase. We also reproduced cartilage tissue formation by the injection of elastic cartilage-derived cells with the gelatinous mass into the subcutaneous space of the nude mouse. The synthesis of gelatinous matrix in vitro and the formation of cartilage tissue in vivo could be obtained only for the combination of elastic cartilage-derived cells with redifferentiation medium. This study was supported in part by grants from the “Japan Society for the Promotion of Science (19591752)” and “Center of Excellence Program for Frontier Research on Molecular Destruction and Reconstruction of Tooth and Bone in Tokyo Medical and Dental University” to Takeshi Muneta, and the “Japan Society for the Promotion of Science (18591657)” to Ichiro Sekiya.     

Long-Term Foraging Expeditions (Molongo) among the Baka Hunter-Gatherers in the Northwestern Congo Basin, with Special Reference to the “Wild Yam Question”

While “Pygmy” hunter-gatherers have generally been assumed to be the original inhabitants of the central African rainforest, recent studies dispute the viability of subsistence in tropical rainforests through foraging alone. There are, however, few studies that are based on sound data of actual long-term foraging. This paper examines the viability of “pure” foraging in tropical rainforests, based on data from participant observation of a long-term foraging expedition among the Baka in the northwestern Congo Basin. The group was observed to subsist solely on wild food resources, particularly wild yams, for two-and-half months. The study was carried out during the dry season when food resources are generally thought to be scarce in tropical rainforests.     

“Force-Talk” in Evolutionary Explanation: Metaphors and Misconceptions

The notion of “pressure” as an evolutionary “force” that “causes” evolution is a pervasive linguistic feature of biology textbooks, journal articles, and student explanatory discourse. We investigated the consequences of using a textbook and curriculum that incorporate so-called force-talk. We examined the frequency with which biology majors spontaneously used notions of evolutionary “pressures” in their explanations, students’ definitions and explanations of what they meant when they used pressures, and the structure of explanatory models that incorporated evolutionary pressures and forces. We found that 12–20 percent of undergraduates spontaneously used “pressures” and/or “forces” as explanatory factors but significantly more often in trait gain scenarios than in trait loss scenarios. The majority of explanations using “force-talk” were characterized by faulty evolutionary reasoning. We discuss the conceptual similarity between faulty notions of evolutionary pressures and linguists’ force-dynamic models of everyday reasoning and ultimately question the appropriateness of force-talk in evolution education.     

Modeling of Competitive Mutualistic Relationships. Application to Cellulose Degradation by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. Strains

A “cascade” model depicts microbial degradation of a complex nutrient/substrate through a succession of intermediate compounds. Each stage is characterized by a particular species producing a typical degradation enzyme induced by its own degradation product. The final compound of the cascade consists of a single assimilable substrate used by all species. This results in a competition situation, whereas the contribution of all strains to the production of a complete set of efficient enzymes generates a mutualistic relationship. The model was shown to be appropriate to describe degradation of cellulose by a consortium of Streptomyces sp. strains. The simplicity and the model capacity for generalization are promising and could be used for various degradation processes both at laboratory and environmental scales.     

The Jackprot Simulation Couples Mutation Rate with Natural Selection to Illustrate How Protein Evolution Is Not Random

Protein evolution is not a random process. Views which attribute randomness to molecular change, deleterious nature to single-gene mutations, insufficient geological time, or population size for molecular improvements to occur, or invoke “design creationism” to account for complexity in molecular structures and biological processes, are unfounded. Scientific evidence suggests that natural selection tinkers with molecular improvements by retaining adaptive peptide sequence. We used slot-machine probabilities and ion channels to show biological directionality on molecular change. Because ion channels reside in the lipid bilayer of cell membranes, their residue location must be in balance with the membrane’s hydrophobic/philic nature; a selective “pore” for ion passage is located within the hydrophobic region. We contrasted the random generation of DNA sequence for KcsA, a bacterial two-transmembrane-domain (2TM) potassium channel, from Streptomyces lividans, with an under-selection scenario, the “jackprot,” which predicted much faster evolution than by chance. We wrote a computer program in JAVA APPLET version 1.0 and designed an online interface, The Jackprot Simulation , to model a numerical interaction between mutation rate and natural selection during a scenario of polypeptide evolution. Winning the “jackprot,” or highest-fitness complete-peptide sequence, required cumulative smaller “wins” (rewarded by selection) at the first, second, and third positions in each of the 161 KcsA codons (“jackdons” that led to “jackacids” that led to the “jackprot”). The “jackprot” is a didactic tool to demonstrate how mutation rate coupled with natural selection suffices to explain the evolution of specialized proteins, such as the complex six-transmembrane (6TM) domain potassium, sodium, or calcium channels. Ancestral DNA sequences coding for 2TM-like proteins underwent nucleotide “edition” and gene duplications to generate the 6TMs. Ion channels are essential to the physiology of neurons, ganglia, and brains, and were crucial to the evolutionary advent of consciousness. The Jackprot Simulation illustrates in a computer model that evolution is not and cannot be a random process as conceived by design creationists.     

Proteasome system of protein degradation and processing

In eukaryotic cells, degradation of most intracellular proteins is realized by proteasomes. The substrates for proteolysis are selected by the fact that the gate to the proteolytic chamber of the proteasome is usually closed, and only proteins carrying a special “label” can get into it. A polyubiquitin chain plays the role of the “label”: degradation affects proteins conjugated with a ubiquitin (Ub) chain that consists at minimum of four molecules. Upon entering the proteasome channel, the polypeptide chain of the protein unfolds and stretches along it, being hydrolyzed to short peptides. Ubiquitin per se does not get into the proteasome, but, after destruction of the “labeled” molecule, it is released and labels another molecule. This process has been named “Ub-dependent protein degradation”. In this review we systematize current data on the Ub-proteasome system, describe in detail proteasome structure, the ubiquitination system, and the classical ATP/Ub-dependent mechanism of protein degradation, as well as try to focus readers’ attention on the existence of alternative mechanisms of proteasomal degradation and processing of proteins. Data on damages of the proteasome system that lead to the development of different diseases are given separately.     

Is there a Real Nexus Between Ethics and Aesthetics?

Aesthetics is a vexed topic in philosophy, with a long history. For my purposes, an aesthetic experience is a foundational affective response to an object, to which terms such as “ugly”, “beautiful”, “pretty” or “harmonious” are applied. These terms are derived from a Discourse of aesthetics; some remain constant, others change from generation to generation. Aesthetics and ethics have been linked in Western thought since the days of Plato and Aristotle. This essay examines what is happening to that link in contemporary experience. It emphasises the ways in which the popular media exploit aesthetic appeal to penetrate their market, and to exploit and frame intuitive responses to current and past events. Production values, the artfulness of editors and the financial interests of producers and directors thus do much to determine contemporary aesthetic and ethical judgements. That which is beautifully presented invites the ethical involvement of the audience. Events whose images are beautifully presented constitute “hyperevidence”, a pre-judged, reinforced and amplified illusion of reality and participation. Understanding how aesthetic excellence draws audiences into ethical relationship with what is presented becomes an important part of education in ethics, including bioethics.     

Circumscription of Malvaceae (Malvales) as determined by a preliminary cladistic analysis of morphological, anatomical, palynological, and chemical characters

We report a phylogenetic analysis of “core” Malvales (Tiliaceae, Sterculiaceae, Bombacaceae, and Malvaceae) based on morphological, anatomical, palynological, and chemical features. The results of the analyses lead to the conclusion that Tiliaceae, Sterculiaceae, and Bombacaceae, as variously delimited, are paraphyletic; only the Malvaceae are likely monophyletic. The genera of “core” Malvales form a well-defined clade. Genera of “Tiliaceae” constitute the basal complex within “core” Malvales. The “Sterculiaceae” (most genera)+ “Bombacaceae” + Malvaceae form a clade on the basis of a monadelphous androecium; “Bombacaceae”+ Malvaceae also form a clade, which is diagnosable on the basis of monoloculate anthers. It is clear that the traditional classification, with its arbitrarily delimited evolutionary grades, is unsatisfactory, especially if one seeks to reflect phylogeny accurately. Thus, Malvaceae is redefined to refer to the most recent common ancestor of plants previously considered to be “Tiliaceae,” “Sterculiaceae,” “Bombacaceae,” and Malvaceae, and all of the descendants of that ancestor. This broadly circumscribed Malvaceae can be diagnosed by several presumed synapomorphies, but we draw special attention to the unusual floral nectaries that are composed of densely packed, multicellular, glandular hairs on the sepals (or less commonly on the petals or androgynophore).     

Direct use values and passive use values: implications for conservation of large carnivores

We made a quantitative analysis of the responses of urban and rural residents in Sweden to arguments supporting and opposing conservation of large carnivores. The most important arguments in favour of conservation were: “I want them [the large carnivores] to exist in Sweden, even if I will never see any of them”, “Sweden should share the responsibility of conserving the large carnivores” and “We owe it [conservation of large carnivores] to future generations”. We found only small differences between rural and urban residents. For arguments opposing conservation, the difference between rural and urban areas was slightly greater. The most important arguments opposing conservation of large carnivores were: “They may have serious negative impact on livestock farming”, “They may have serious negative impact on reindeer husbandry” and “May inflict suffering on injured livestock”. We conclude that there seems to be less support for direct use values such as hunting, ecotourism or just experiencing large carnivores, this may imply that the minimum viable population size can be used as a long-term management goal for large carnivore populations, possibly with an exception for bears. We also conclude that a separate conservation or management plan is needed for each species, since the conflicts with human interests vary greatly between the different carnivore species.     

The Growing Visibility of Creationism in Northern Ireland: Are New Science Teachers Equipped to Deal with the Issues?

The growing visibility of various forms of creationism in Northern Ireland raises issues for science education. Attempts have been made at political levels to have such “alternatives” to evolution taught in the science classroom, and the issue has received coverage in local press and media. A sample of 112 pre-service science teachers answered a survey on attitudes toward evolution. Preliminary analysis revealed many of these new teachers held views contrary to scientific consensus—over one fifth doubt the evidence for human evolution, and over one quarter dispute the common ancestry of life. Over two thirds indicated a preference for teaching a “range of theories” regarding these issues in science. In addition, 49 pre-service biology teachers viewed a DVD resource promoting “intelligent design” and completed an evaluation of it. The biology teachers also took part in either focus groups or additional questionnaires. A majority took the resource at face value and made positive comments regarding its utility. Many articulated views contrary to the stated positions of science academies, professional associations, and the UK government teaching directives regarding creationism. Most indicated a perception that intelligent design is legitimate science and that there is a scientific “controversy” regarding the legitimacy of evolution. Concern is raised over the ability of these new teachers to distinguish between scientific and non-scientific theories. The suggestion is made that the issue should be addressed directly with pre-service science teachers to make clear the status of such “alternatives.” The paper raises implications for science education and questions for further research.

pH-Induced Molten Globule State of <Emphasis Type="Italic">Rhizopus niveus</Emphasis> Lipase is More Resistant Against Thermal and Chemical Denaturation Than Its Native State

Here, we have characterized four pH-dependent states: alkaline state, “B” (pH 9.0), native state, “N” (pH 7.4), acid-induced state, “A” (pH 2.2) and molten globule state, “MG” (pH 1.8) of Rhizopus niveus lipase (RNL) by CD, tryptophanyl fluorescence, ANS binding, DLS, and enzyme activity assay. This “MG” state lacks catalytic activity and tertiary structure but it has native-like significant secondary structure. The “R _h” of all the four states of RNL obtained from DLS study suggests that the molecular compactness of the protein increases as the pH of solution decreases. Kinetic analysis of RNL shows that it has maximum catalytic efficiency at state “B” which is 15-fold higher than state “N.” The CD and tryptophanyl fluorescence studies of RNL on GuHCl and temperature-induced unfolding reveal that the “MG” state is more stable than the other states. The DSC endotherms of RNL obtained at pH 9.0, 7.4, and 2.2 were with two transitions, while at pH 1.8 it showed only a single transition.     

J D Bernal (1901–1971) in perspective

Conclusion We must conclude that the sub-title of Bernal’s “The Social Function of Science” — “What science does: what science could do” is still the relevant challenge and indicates Bernal’s chief contribution, besides the foundation of molecular biology to our civilization. It is manifest that resources spent on armaments are a monstrous pathological symptom of our social structure. The ancient problem of “what is property” and what may be “owned” and by whom or by what organs of society is awakening.     

Inheritance of resistance to Plum pox virus in apricot (Prunus armeniaca L.)

The inheritance of resistance to Plum pox virus (PPV) has been studied in 1,178 apricot hybrids. Seven hundred and eighteen F1 hybrids, obtained from controlled crosses between the susceptible Greek cultivar “Bebecou” and the resistant PPV cultivars of American origin (“Stark Early Orange,” ‘NJA2,” ‘Veecot,” “Sunglo,” “Harlayne,” and “Orangered”) were evaluated for resistance to the PPV-M (Marcus) strain, 8 years after artificial inoculation. The inheritance of resistance to PPV has been additionally studied for the first time in a BC₁ population of 95 apricot hybrids for four vegetative periods. Reaction of each hybrid to PPV-M was scored through visual symptoms, indexing onto GF-305 and double-antibody sandwich enzyme-linked immunosorbent assay tests. Segregation within the hybrids, determined by Chi-squared analysis, fits a 1:1 ratio (P ≤ 0.05) of the resistant vs susceptible, indicating that resistance to PPV is controlled by a single dominant gene locus and that the above six resistant cultivars are heterozygous for the trait. Plants carrying this gene may initially develop disease symptoms on leaves but eventually recover and no virus can be detected in leaves. Susceptible plants show similar symptoms initially but remain symptomatic. Inheritance of resistance to PPV also has been studied in 365 F1 hybrids by crossing the resistant cultivar “Stella” with the susceptible “Bebecou” and the resistant cultivars “Sunglo” and “NJA2,” for 8 years after inoculation. The segregation ratio was 1:0 (resistant/susceptible) suggesting that “Stella” is homozygous for the resistance trait. The purpose of this work was the enhancement of the knowledge of inheritance of resistance to PPV for the selection of new cultivars.     

“Good Mothering” or “Good Citizenship”? Conflicting Values in Choosing Whether to Donate or Store Umbilical Cord Blood

Umbilical cord blood banking is one of many biomedical innovations that confront pregnant women with new choices about what they should do to secure their own and their child’s best interests. Many mothers can now choose to donate their baby’s umbilical cord blood (UCB) to a public cord blood bank or pay to store it in a private cord blood bank. Donation to a public bank is widely regarded as an altruistic act of civic responsibility. Paying to store UCB may be regarded as a “unique opportunity” to provide “insurance” for the child’s future. This paper reports findings from a survey of Australian women that investigated the decision to either donate or store UCB. We conclude that mothers are faced with competing discourses that force them to choose between being a “good mother” and fulfilling their role as a “good citizen.” We discuss this finding with reference to the concept of value pluralism.     

Md-ACS1 and Md-ACO1 genotyping of apple (<Emphasis Type="Italic">Malus</Emphasis> x <Emphasis Type="Italic">domestica</Emphasis> Borkh.) breeding parents and suitability for marker-assisted selection

Fruit ethylene production genotypes for Md-ACS1 and Md-ACO1 were determined for 60 apple cultivars and 35 advanced breeding selections. Two alleles for each gene are commonly found in cultivated apple. Earlier studies showed that genotypes homozygous for the ACS1-2 allele produce less ethylene and have firmer fruit than ACS1-1/2 and ACS1-1/1 genotypes. ACO1 plays a minor role compared to ACS1, with homozygous ACO1-1 having lower ethylene production. In this study, ACS1-2 and ACO1-1 homozygotes had firmer fruit at harvest and after 60 days of 0–1°C cold storage compared to other genotypes. These genotypes, ACS1-2/2 and ACO1-1/1, were observed for the following 8 of 95 cultivars/selections: “Delblush”, “Fuji”, “Pacific Beauty”, “Sabina” and four breeding selections. Cultivars/selections that were homozygous ACS1-2 but not ACO1-1 were: “Ambrosia”, “Aurora Golden Gala”, “CrimsonCrisp”, “Gala”, “GoldRush”, “Huaguan”, “Pacific Rose, “Pacific Queen”, “Pinova”, “Sansa”, “Sonja”, “Sundance”, “Zestar”, and 17 breeding selections. Cultivars with the heterozygous ACS1-1/2 genotype were “Arlet”, “Braeburn”, “Cameo”, “Delicious”, “Delorgue”, “Empire”, “Enterprise”, “Ginger Gold”, “Golden Delicious”, “Granny Smith”, “Honeycrisp”, “Orin”, “Pink Lady”, “Silken”, “Suncrisp”, “Sundowner”, “Sunrise” and 11 breeding selections. No cultivars were detected homozygous for both ACS1-1 and ACO1-1, or for both ACS1-2 and ACO1-2. This study is the first large-scale allelic genotyping of both ethylene synthesis genes for a comprehensive set of apple breeding parents used in an ongoing breeding project. The data reported here are important for informative selection of parent combinations and marker-assisted selection of progeny for breeding low ethylene-producing apple cultivars for better storability and improved consumer acceptance.     

The metabolism of proline,a stress substrate,modulates carcinogenic pathways

The resurgence of interest in tumor metabolism has led investigators to emphasize the metabolism of proline as a “stress substrate” and to suggest this pathway as a potential anti-tumor target. Proline oxidase, a.k.a. proline dehydrogenase (POX/PRODH), catalyzes the first step in proline degradation and uses proline to generate ATP for survival or reactive oxygen species for programmed cell death. POX/PRODH is induced by p53 under genotoxic stress and initiates apoptosis by both mitochondrial and death receptor pathways. Furthermore, POX/PRODH is induced by PPARγ and its pharmacologic ligands, the thiazolidinediones. The anti-tumor effects of PPARγ may be critically dependent on POX/PRODH. In addition, it is upregulated by nutrient stress through the mTOR pathway to maintain ATP levels. We propose that proline is made available as a stress substrate by the degradation of collagen in the microenvironmental extracellular matrix by matrix metalloproteinases. In a manner analogous to autophagy, this proline-dependent process for bioenergetics from collagen in extracellular matrix can be designated “ecophagy”.