Higher sensitivity to perithreshold odors when sitting than when supine may be correlated with postural differences in locus coeruleus activity

Lundström et al. (2007) report an effect of posture onperithreshold odor sensitivity, which they found to be higherwhen sitting than when lying down (consistent with earlier workdescribed in Lundstrom et al. 2006). The explanation for thisresult focused on cognitive mechanisms, with support seen inthere being     

Information transmission in non-visual fingertip matching along a horizontal track in the median plane

Non-visually triggered arm movements over a horizontal table at shoulder height were analysed by an Information Theory approach according to a method suggested by Sakitt et al. (1983) and Sakitt (1980). The movement track was along the subject's median line and was indicated by a vertical metal ridge fixed to the table. The observer passively moved the subject's left index finger along the left side of the ridge to the target position. The blindfolded subject then had to move his right index finger along the right side of the ridge to match the left finger position. Direct contact between the two fingers was prevented by the ridge. We compared our results, which involve the transmission of information through the arm and shoulder joints of both arms, whith those of Sakitt et al. which involved just one elbow joint. We supplemented our experimental results with simulations and show that the value for the transmitted information, obtained using the method of analysis suggested by Sakitt et al., is very dependent upon the number of trials, and number and spacing of the targets. Sakitt et al. suggest that the Information Theory approach permits easy comparison between different tasks and different observers. Our results suggest that comparisons should be made with caution.     

Smelling excitement in the antennal lobe

In the fly antennal lobe projection neurons receive odor information from olfactory sensory neurons and transmit it to higher brain centers. However, projection neurons respond differently to odors than sensory neurons, despite the fact that they appear to have one-to-one connectivity. Shang et al. (2007) now describe the existence of excitatory neurons within the antennal lobe that may account for some of these unexplained differences.     

Problems in the experimental determination of substrate-specific H+/O ratios during respiration

Krabet al. (1984) have recently tried to resolve the long-standing controversy as to whether the mechanistic H⁺/O coupling ratio for electrons passing through sites II and III of the mammalian electron transport chain to O₂ is 6 or 8. Using a mathematical model they concluded that the higher number reported by Costaet al. (1984) was an overestimate because of the unaccounted for delayed response of the O₂ electrode. Responding to criticisms of Lehningeret al. (1985), they have recently used (Krab and Wikström, 1986) an improved mathematical model which shows that the higher number found by Costaet al. was probably due to an inadequate accounting for the effects of the proton leak process which accompanies the translocation process. The impression is left that the situation is now resolved in favor of the lower number. We agree that the procedures of Costaet al. do not properly account for the leak process, and provide further evidence in this paper of the magnitude of the problem. However, we disagree that the number 6.0, favored by Wikströmet al., rests on any more solid experimental support. We provide evidence here for this conclusion and raise the question as to whether or not any unique, fixed, integral number exists for the H⁺/O ratio accompanying the oxidation of a particular substrate.     

Robust generation of hepatocyte-like cells from human embryonic stem cell populations

Despite progress in modelling human drug toxicity, many compounds fail during clinical trials due to unpredicted side effects. The cost of clinical studies are substantial, therefore it is essential that more predictive toxicology screens are developed and deployed early on in drug development (Greenhough et al 2010). Human hepatocytes represent the current gold standard model for evaluating drug toxicity, but are a limited resource that exhibit variable function. Therefore, the use of immortalised cell lines and animal tissue models are routinely employed due to their abundance. While both sources are informative, they are limited by poor function, species variability and/or instability in culture (Dalgetty et al 2009). Pluripotent stem cells (PSCs) are an attractive alternative source of human hepatocyte like cells (HLCs) (Medine et al 2010). PSCs are capable of self renewal and differentiation to all somatic cell types found in the adult and thereby represent a potentially inexhaustible source of differentiated cells. We have developed a procedure that is simple, highly efficient, amenable to automation and yields functional human HLCs (Hay et al 2008 ; Fletcher et al 2008 ; Hannoun et al 2010 ; Payne et al 2011 and Hay et al 2011). We believe our technology will lead to the scalable production of HLCs for drug discovery, disease modeling, the construction of extra-corporeal devices and possibly cell based transplantation therapies.     

Mechanosensitivity below Ground: Touch-Sensitive Smell-Producing Roots in the Shy Plant Mimosa pudica

The roots of the shy plant Mimosa pudica emit a cocktail of small organic and inorganic sulfur compounds and reactive intermediates into the environment, including SO₂, methanesulfinic acid, pyruvic acid, lactic acid, ethanesulfinic acid, propanesulfenic acid, 2-aminothiophenol, S-propyl propane 1-thiosulfinate, phenothiazine, and thioformaldehyde, an elusive and highly unstable compound that, to our knowledge, has never before been reported to be emitted by a plant. When soil around the roots is dislodged or when seedling roots are touched, an odor is detected. The perceived odor corresponds to the emission of higher amounts of propanesulfenic acid, 2-aminothiophenol, S-propyl propane 1-thiosulfinate, and phenothiazine. The mechanosensitivity response is selective. Whereas touching the roots with soil or human skin resulted in odor detection, agitating the roots with other materials such as glass did not induce a similar response. Light and electron microscopy studies of the roots revealed the presence of microscopic sac-like root protuberances. Elemental analysis of these projections by energy-dispersive x-ray spectroscopy revealed them to contain higher levels of K⁺ and Cl⁻ compared with the surrounding tissue. Exposing the protuberances to stimuli that caused odor emission resulted in reductions in the levels of K⁺ and Cl⁻ in the touched area. The mechanistic implications of the variety of sulfur compounds observed vis-à-vis the pathways for their formation are discussed.Plant roots are known to exude a diversity of both small and macromolecular chemicals that mediate antimicrobial, antiquorum sensing, allelopathic, and other effects (De-la-Peña et al., 2012). However, the machinery associated with the synthesis and extrusion of these compounds is not well understood. One of the most intriguing but least studied of these is the emission of volatile and reactive organosulfur compounds such as the foul and toxic gas carbonyl sulfide (COS) and volatile carbon disulfide (CS₂). Both are reportedly released by numerous plants and are proposed to make a significant contribution to the environmental sulfur burden (Haines et al., 1989). As a case in point, the Central American rainforest plant Stryphnodendron exelsum (Mimosaceae) is a sufficiently strong sulfur emitter that its location in the forest can be determined by odor (Haines et al., 1989). Furthermore, 40 taxa from nine genera within the subfamily Mimosoideae revealed that 29 taxa from six genera produced CS₂ and 19 of the 40 taxa produced COS (Piluk et al., 2001). It has been proposed that the COS and CS₂ are derived from a putative Cys lyase-mediated cleavage of djenkolic acid, an amino acid previously isolated from the plant (Piluk et al., 1998), but this has not been confirmed.We used Mimosa pudica (Leguminosae), a perennial shrub endemic to Brazil but now pantropical in its distribution (Howard, 1988), as a model to begin investigations of how this and related plants emit these highly reactive and corrosive compounds without themselves incurring tissue damage. Its various colloquial names, such as sensitive plant, touch-me-not, shy plant, and humble plant, among many others (Holm, 1977), derive from its seismonastic movements: in response to touch, water, shaking, wind, or warming, its leaves quickly close, slowly opening after an average of about 10 min (Song et al., 2014). It also displays nyctinasty, with its leaves closing or “sleeping” with the onset of darkness. These curious characteristics coupled with its small size have made the plant a convenient and popular attraction in schools, greenhouses, and other learning environments, where it is used to illustrate seismonasty.Our studies show that by using direct analysis in real time high-resolution mass spectrometry (DART-HRMS; Cody et al., 2005), it is possible to detect the compounds emitted by plant roots in situ. Using this method, it was revealed that both M. pudica plants germinated aseptically on agar and those germinated in soil emitted a variety of small molecules into the atmosphere at levels that were not detectable by human subjects. However, an odor detectable by humans could be sensed when the plant root was disturbed, with odor emission being dependent on the nature of the stimulus. Analysis of the chemical contributors to the odor revealed that, although the array of compounds observed to be produced by the roots was the same both before and after stimulation, emission of a subset of organosulfur compounds was increased when the roots were stimulated. Light and scanning electron microscope imaging studies revealed the presence of sac-like protuberances dotted along M. pudica seedling root shafts that collapsed when the roots were exposed to stimuli that elicited odor emission. The detection by energy-dispersive x-ray spectroscopy (EDS) of relatively high levels of K⁺ and Cl⁻ prior to root stimulation, on the one hand, and reductions in the levels of these species, on the other hand, implicate the involvement of these ions in the observed mechanostimulatory behavior.     

Chemical defense in the firefly,Rhagophthalmus ohbai (Coleoptera: Rhagophthalmidae)

Rhagophthalmus ohbai Wittmer (Iriomote botaru, in Japanese) can be found in the soil environment on several islands in Okinawa Prefecture, Japan. The females of this species have been reported to remain in very close proximity to their eggs for about 2 months while producing a pungent odor. We hypothesized that females produced this odor in order to protect their eggs and/or themselves from pathogens and/or predators. Analysis of this volatile substance by solid-phase microextraction and gas chromatography mass spectrometry (GC–MS) revealed that the odor was attributed to 1,4-naphthoquinone (NQ). We also examined resistance to NQ in four fungi isolated from dead fireflies [Aspergillus tubingensis (Schober) Mosseray 21KI501, A. fumigatus Fresenius 21KI502, Fusarium proliferatum (Matsushima) Nirenberg 21KI503, and Trichoderma asperellum Samuels et al. 21KI504], as well as four common soil bacteria [Escherichia coli (Migula) Castellani and Chalmers type B, Staphylococcus aureus subsp. aureus Rosenbach H209P, Bacillus subtilis (Ehrenberg) Cohn ATCC6633, and Rhodococcus jostii Takeuchi et al. RHA1]. The findings revealed that NQ exhibited antimicrobial activity in all of the test organisms, suggesting that female fireflies release NQ to protect their eggs and newly hatched larvae from pathogens in the soil. We also analyzed the volatiles produced by male fireflies using GC–MS and found that some male fireflies emitted NQ. It is possible that male fireflies produce NQ to protect themselves from pathogenic microorganisms in the soil environments that they inhabit during the day. Although several defensive chemicals produced by fireflies have been identified to date, the production of 1,4-naphthoquinone for chemical defense by R. ohbai has not yet been reported.     

A fruity note: crossmodal associations between odors and musical notes

Odors are notoriously difficult to describe, but they seem prone to a variety of crossmodal associations. In the present study, we generalize the previously-shown association between odors (from perfumery) and pitch (Belkin et al. 1997) to odors related to food and drink (in this case those associated with wine). We also demonstrate that, to a lesser extent (25% of the odor tested), participants preferentially match specific odors to certain types of instruments. The ratings of the odors along a number of dimensions are used in principal components analysis (PCA) to explore the psychological dimensions underlying the odor-pitch associations. The results demonstrate that both pleasantness and complexity, but not intensity, appear to play a role when choosing a pitch to match an odor. Our results suggest that these features of odor stimuli constitute psychological dimensions that can be consistently matched to auditory features.     

Using lobster noses to inspire robot sensor design

Robots are needed to locate the sources of toxic chemical plumes. Lobsters, which track odor plumes for many ecologically crucial activities, can provide inspiration for robot designers. Before accurate search strategies for robots can be developed, how odor molecules are captured by the lobster's chemosensors must be understood. A recent study by Koehl et al. shows how lobster olfactory antennules alter the patterns of concentration in turbulent odor plumes during odor sampling.     

Forgetting those painful moments

We all know that memories fade-although not always as quickly as we would like. What molecular and cellular processes underlie forgetting? In this issue of Neuron, Schwaerzel et al. indicate that extinction of an odor memory in Drosophila may involve the same neurons as those involved in forming the memory.     

Interhemispheric olfactory circuit and the memory beyond

In mammals, olfactory sensory neurons project their axons exclusively to the ipsilateral olfactory bulb. It remains unclear how odor information interacts between the two hemispheres of the brain. In this issue of Neuron, Yan et al. describe the precise interbulbar connection through the anterior olfactory nucleus pars externa (AONpE), which links contralateral isotypic olfactory columns.     

An IS4 transposition causes a 13-bp duplication of phage lambda DNA and results in the constitutive expression of the cI and cro gene products

We have examined the nature of the additional DNA present in lambda hyp- mutants (Eisen et al., 1982). This DNA is an IS4 element in orientation I, in the y region of bacteriophage lambda at nucleotide position 39,139 (see Moore et al., 1979). Our assignment is based on (i) the similarity in size derived from the PstI, AvaI, and HindII restriction pattern and (ii) the DNA sequence of both the left and right lambda-IS4 DNA junctions in phage lambda hyp15rev4. The IS4 integration event resulted in the duplication of 13 bp of lambda DNA in contrast to the 11- and 12-bp duplications previously observed at the sites of IS4 integrations elsewhere (Klaer et al., 1981).     

Targeting TGF-beta and the extracellular matrix in Marfan's syndrome

Marfan's syndrome is a genetic disorder affecting connective tissues, and it can lead to death due to aortic defects if left untreated. beta-blocker therapy has been used to slow the progression of this disease. Brooke et al. (2008) now report that combining angiotensin II receptor blockade by losartan with beta-blocker treatment is an effective treatment combination therapy for this disorder.     

Olfactory conditioning with single chemicals in the German Cockroach, Blattella germanica (Dictyoptera: Blattellidae)

Many insects find resources by means of the olfactory cues of general odors after learning. To evaluate behavioral responses to the odor of a particular chemical after learning with reward or punishment quantitatively, we developed a standardized odor-training method in the German cockroach, Blattella germanica (Linnaeus), an important urban pest species. A classical olfactory conditioning procedure for a preference test was modified to become applicable to a single odor, by which a (?)-menthol or vanillin odor was independently associated with sucrose (reward) or sodium chloride solution (punishment). The strength of the association with the odor was evaluated with the increase or decrease in visit frequencies to the odor source after olfactory conditioning. The frequency increased after (?)-menthol was presented with a reward, while it did not change with the rewarded vanillin odor. With both odors, the frequency decreased significantly after training with a punishment. These results indicate that cockroaches learn a single compound odor presented as a conditioned stimulus, although the association of the odor with a reward or punishment depends on the chemical. This olfactory conditioning method can not only facilitate the analysis of cockroach behavior elicited by a learned single chemical odor, but also quantify the potential attractiveness or repellency of the chemical after learning.     

A private allele ubiquitous in the Americas

The three-wave migration hypothesis of Greenberg et al. has permeated the genetic literature on the peopling of the Americas. Greenberg et al. proposed that Na-Dene, Aleut-Eskimo and Amerind are language phyla which represent separate migrations from Asia to the Americas. We show that a unique allele at autosomal microsatellite locus D9S1120 is present in all sampled North and South American populations, including the Na-Dene and Aleut-Eskimo, and in related Western Beringian groups, at an average frequency of 31.7%. This allele was not observed in any sampled putative Asian source populations or in other worldwide populations. Neither selection nor admixture explains the distribution of this regionally specific marker. The simplest explanation for the ubiquity of this allele across the Americas is that the same founding population contributed a large fraction of ancestry to all modern Native American populations.     

Hemispheric lateralization in the processing of odor pleasantness versus odor names

It is well established that for most people linguistic processing is primarily a left hemisphere activity, whereas recent evidence has shown that basic odor perception is more lateralized to the right hemisphere. Importantly, under certain conditions, emotional responding also shows right hemisphere laterality. Hedonic (pleasantness) assessments constitute basic level emotional responses. Given that olfaction is predominantly ipsilateral in function, it was hypothesized that odor pleasantness evaluations may be accentuated by right nostril perception and that odor naming would be superior with left nostril perception. To test this prediction we presented eight familiar neutral-mildly pleasant odors for subjects to sniff through the left and right nostrils. Subjects smelled each odor twice (once through each nostril) at two different sessions, separated by 1 week. At each session subjects provided pleasantness, arousal and naming responses to each odorant. Results revealed that odors were rated as more pleasant when sniffed through the right nostril and named more correctly when sniffed through the left. No effects for arousal were obtained. These findings are consistent with previously demonstrated neural laterality in the processing of olfaction, emotion and language, and suggest that a local and functional convergence may exist between olfaction and emotional processing.     

Predator Recognition and Learned Irrelevance in the Crayfish Orconectes virilis

When individuals of the crayfish Orconectes virilis detect an unlearned danger cue (alarm odor) and a novel cue (goldfish odor) at the same time, they form a learned association and behave as if the novel cue is associated with increased predation risk ( Hazlett et al. 2002 ). This study examined the potential for learned irrelevance in O. virilis and the circumstances under which blockage of the formation of a learned association could occur. If individuals experience a random pattern of alarm odor and goldfish odor over the days prior to the simultaneous detection of those two cues, no learned association is formed (= learned irrelevance). That is, there is no inhibition of responses to a food cue when goldfish odor is added if the crayfish has experienced a random pattern of the two cues. Learning was eliminated if the random pattern of cues was experienced before or after the simultaneous detection. To present the two cues (alarm and goldfish odors) to crayfish independently on separate days, the water containing goldfish odor had to be removed from the aquaria as the odor persisted at least 24 h. The importance of the learned irrelevance phenomenon on predator–prey interactions is discussed.     

荔枝霜疫霉的研究

对华南的荔枝霜疫霉(Peronophythora litchii Chen ex Ko et al)的形态和营养特性进行了研究,并和新模式种进行了比较。发现此菌孢囊梗的生长是一种有限-无限生长类型,或称之为多级有限生长。即孢囊梗上的小分枝大多数是有限生长的,在其顶端同时形成孢子囊。但有时在同一孢囊梗上有的小分枝会继续生长,形成二级、三级甚至四级孢囊梗。在营养要求上与疫霉无大差别,能在天然和合成培养基上旺盛生长,需要硫胺素,ca~(++)和有机二元酸,能利用NH_4~+ 或No_3~-为其氮源,并能利用淀粉为其碳源,菌体匀浆中测出淀粉酶活性。根据孢囊梗的独特生长方式,我们认为完全有理由承认这菌是一个新属,并可成为新科,霜疫霉科。本文中已将霜疫霉科作了修改描述。孢囊梗已被修改为:孢囊梗多级有限生长。无疑这菌是腐霉科和霜霉科的中间类型。在营养类型与有性器官上和疫霉相近,而其孢子囊的形成和霜霉相似。但其孢囊梗的多级有限生长方式则和这两科都不相同。     

Lack of Staphylococcal Enterotoxin Production among Strains of Staphylococcus aureus from Bovine Mastitis in Denmark

Staphylococcal enterotoxins (SE’s) are a group of small exoproteins produced by some strains of Staphylococcus aureus. The SE’s, designated A to E according to their antigenic specificities, are important causes of food poisoning worldwide. Milk and dairy products are frequently associated with S. aureus enter-otoxin food poisoning, and it is supposed that infected milk from mastitic animals constitute the main source of enterotoxigenic S. aureus of animal origin (Bryon 1983, Gilmour & Harvey 1990, Bergdoll 1989). Indeed, S. aureus is the most common cause of bovine mastitis worldwide, and if mastitis strains produce SE this makes up an enormous reservoir of potential enterotoxin producers. The production of SE by S. aureus isolated from bovine mastitis have been investigated in several countries (Matsunaga et al. 1993, Kenny et al. 1993, Olson et al 1970, Orden et al. 1992, Olsvik et al. 1981, Adekeye 1980, Garcia et al. 1980, Abbar 1986, Harvey & Gilmour 1985). Since no studies have been performed on the prevalence of enterotoxigenic strains of S. aureus isolated from bovine mastitis in Denmark, a well characterized collection of S. aureus (Aarestrup et al. 1995) was investigated with respect to this property.     

A note on efficient computation of haplotypes via perfect phylogeny.

The problem of inferring haplotype phase from a population of genotypes has received a lot of attention recently. This is partly due to the observation that there are many regions on human genomic DNA where genetic recombination is rare (Helmuth, 2001; Daly et al., 2001; Stephens et al., 2001; Friss et al., 2001). A Haplotype Map project has been announced by NIH to identify and characterize populations in terms of these haplotypes. Recently, Gusfield introduced the perfect phylogeny haplotyping problem, as an algorithmic implication of the no-recombination in long blocks observation, together with the standard population-genetic assumption of infinite sites. Gusfield's solution based on matroid theory was followed by direct theta(nm2) solutions that use simpler techniques (Bafna et al., 2003; Eskin et al., 2003), and also bound the number of solutions to the PPH problem. In this short note, we address two questions that were left open. First, can the algorithms of Bafna et al. (2003) and Eskin et al. (2003) be sped-up to O(nm + m2) time, which would imply an O(nm) time-bound for the PPH problem? Second, if there are multiple solutions, can we find one that is most parsimonious in terms of the number of distinct haplotypes. We give reductions that suggests that the answer to both questions is "no." For the first problem, we show that computing the output of the first step (in either method) is equivalent to Boolean matrix multiplication. Therefore, the best bound we can presently achieve is O(nm(omega-1)), where omega < or = 2.52 is the exponent of matrix multiplication. Thus, any linear time solution to the PPH problem likely requires a different approach. For the second problem of computing a PPH solution that minimizes the number of distinct haplotypes, we show that the problem is NP-hard using a reduction from Vertex Cover (Garey and Johnson, 1979).