Investigating the risks of removing wild meat from global food systems

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Bite Injuries of Grey Seals (Halichoerus grypus) on Harbour Porpoises (Phocoena phocoena)

Bite-like skin lesions on harbour porpoises (Phocoena phocoena) have been suspected to be caused by grey seals (Halichoerus grypus), and a few field observations have been reported. Bite-like skin lesions observed on stranded animals were characterized by two main components: large flaps of loose or missing skin and blubber with frayed edges and puncture lesions. Definitive demonstration of predation by a grey seal was not reported so far in those stranded animals. In this study, five stranded porpoises with bite-like skin lesions were swabbed for genetic investigations. In addition, the head of a recently dead grey seal was used to mimic bite-like skin injuries on a porpoise carcass. Subsequently, the artificial skin injuries were swabbed, along with the gum of the seal used for inflicting them (positive controls). Total DNA was extracted from the swabs and was used to retrieve a fragment of mitochondrial DNA by PCR. Primers were designed to amplify a specific stretch of mitochondrial DNA known to differ between grey seals and porpoises. The amplicon targeted was successfully amplified from the positive control and from two of the stranded porpoises, and grey seal-specific mitochondrial DNA was retrieved from all those samples. We conclude that (1) it is possible to detect grey seal DNA from dead porpoises even after several days in seawater and (2) bite-like skin lesions found on dead porpoises definitively result from grey seals attacks. The attacks are most likely linked with predation although, in a number of cases, scavenging and aggressive behaviour cannot be excluded.     

The ecological role of cephalopods and their representation in ecosystem models

Cephalopods, especially squids, are believed to have a structuring role in marine ecosystems as a link between different trophic levels, primarily due to their voracious prey consumption and high production rate. Cephalopod ecology, however, is still poorly understood as observational studies often give highly uncertain and variable results due to the peculiarities of cephalopod behaviour and biology, and their responsiveness to external drivers. This review evaluates our representation of cephalopods in ecosystem models and the insights given by these models on the role of cephalopods in our oceans. We examined ecosystem models from 13 regions to analyse the representation of cephalopods and compared their results to local trophic studies. Our analysis indicated that most ecosystem models inadequately include cephalopods in terms of model structure and parametrization; although some models still have the capacity to draw valuable conclusions regarding the impact and role of cephalopods within the system. Oceanic squid species have a major role linking trophic levels and food webs from different habitats. The importance of neritic species varies locally, but generally cephalopods have a substantial impact via their consumer role. To better understand the ecological role of cephalopods, improved representation of these species in ecosystem models is a critical requirement and could be achieved relatively easily to more accurately articulate the mechanisms regulating the ecological role of cephalopods.

     

Flavones and phenylpropanoids from a sedative extract of Lantana trifolia L.

The flavone glycosides, named scutellarein-7-O-β-d-apiofuranoside and apigenin-7-O-β-d-apiofuranosyl-(1 → 2)-β-d-apiofuranoside, and the flavone celtidifoline (5,6,4′,5′-tetrahydroxy-7,3′-dimethoxyflavone), along with other 11 known compounds, were isolated from leaves of the ethyl acetate extract of Lantana trifolia L. using step gradient High Speed Countercurrent Chromatography (HSCCC) and High Performance Liquid Chromatography (HPLC), respectively. Their structures were elucidated by spectroscopic methods, including 2D NMR and mass spectrometry (ESI-MS) techniques. The ethanolic and ethyl acetate extracts produced an intense sedative effect in mice, one hour after oral administration of 1 mg/kg. This effect was neither due to a benzodiazepine-like effect of the three flavone derivatives neither of the phenylpropanoids, betonyoside F and verbascoside, that were tested for their affinity for the [³H] flunitrazepam binding sites.     

Discriminant analysis of principal components: a new method for the analysis of genetically structured populations

Background

The etiology of complex diseases is due to the combination of genetic and environmental factors, usually many of them, and each with a small effect. The identification of these small-effect contributing factors is still a demanding task. Clearly, there is a need for more powerful tests of genetic association, and especially for the identification of rare effects

Results

We introduce a new genetic association test based on symbolic dynamics and symbolic entropy. Using a freely available software, we have applied this entropy test, and a conventional test, to simulated and real datasets, to illustrate the method and estimate type I error and power. We have also compared this new entropy test to the Fisher exact test for assessment of association with low-frequency SNPs. The entropy test is generally more powerful than the conventional test, and can be significantly more powerful when the genotypic test is applied to low allele-frequency markers. We have also shown that both the Fisher and Entropy methods are optimal to test for association with low-frequency SNPs (MAF around 1-5%), and both are conservative for very rare SNPs (MAF<1%)

Conclusions

We have developed a new, simple, consistent and powerful test to detect genetic association of biallelic/SNP markers in case-control data, by using symbolic dynamics and symbolic entropy as a measure of gene dependence. We also provide a standard asymptotic distribution of this test statistic. Given that the test is based on entropy measures, it avoids smoothed nonparametric estimation. The entropy test is generally as good or even more powerful than the conventional and Fisher tests. Furthermore, the entropy test is more computationally efficient than the Fisher's Exact test, especially for large number of markers. Therefore, this entropy-based test has the advantage of being optimal for most SNPs, regardless of their allele frequency (Minor Allele Frequency (MAF) between 1-50%). This property is quite beneficial, since many researchers tend to discard low allele-frequency SNPs from their analysis. Now they can apply the same statistical test of association to all SNPs in a single analysis., which can be especially helpful to detect rare effects.     

A comparison of human and macaque (Macaca mulatta) immunoglobulin germline V regions and its implications for antibody engineering

Seventy-five V regions encoded by the sequenced genome of one Macaca mulatta specimen have been identified by homology and paired with similar human counterparts. When the human V region of each pair presented no allelic polymorphism, it was directly compared with its homolog. This was the case for 37 pairs and percents of identity ranged between 84–97%. When the human V region presented allelic polymorphism, this polymorphism was found to be significantly smaller (p < 0.0001, p < 0.0001, p = 0.03 for IGHV, IGLV, IGKV regions respectively), 4.2-fold on average, than the differences observed between human and macaque V regions. Similar results were obtained when analyzing framework regions (FRs) only. These results, in agreement with others, demonstrate the existence of differences between human and macaque V regions, confirm the need for the humanization of macaque V regions intended for therapeutic use and call into question the validity of patents relying on the “undistinguishable” character of human and macaque V regions or FRs.Key words: antibody, therapeutic, non-human primate, human, V region, identity, humanization, patent     

Within-species variability of the response to 20-hydroxyecdysone in peach-potato aphid (Myzus persicae Sulzer)

Phytoecdysteroids have been proposed as new tools for controlling crop pests because of their endocrine disruption and deterrent effects on insects and nematodes. There is increasing evidence of variability between taxa in sensitivity to phytoecdysteroids, but the genetic variability of this sensitivity within species is unknown. However, knowledge about this intraspecies variability is required for predicting evolution of the pest's response to new control methods. We assessed the variability of the response of the aphid Myzus persicae Sulzer, a major agricultural pest, to 20-hydroxyecdysone (20E). We determined the number of nymphs produced by six clones of M. persicae exposed to various concentrations of 20E and the capacity of these clones to detect 20E in choice experiments. High concentrations of 20E significantly decreased the number of nymphs produced for two clones and both increases and decreases in the number of offspring were detected at low concentrations. Two clones significantly avoided food with 20E, while one significantly preferred it, suggesting that 20E does not always act as a deterrent in this species. We conclude that genetic variability in the response to 20E exists in natural populations of M. persicae. The consequences of this finding on the sustainability of control methods using 20E are discussed.     

A new and rapid bioassay for the detection of gliotoxin and related epipolythiodioxopiperazines produced by fungi

Gliotoxin is an immunosuppressive cytotoxin produced by numerous environmental or pathogenic fungal species. For this reason, it is one of the mycotoxins which must be systematically searched for in samples for biological control. In this study, a new, rapid and sensitive method for detecting gliotoxin has been developed. This bioassay is based on the induction of morphological changes in cultured cells (human KB cell line) by gliotoxin. Interpretation of the assay can be carried out after 1 h of incubation, either by direct microscopic observation, or with an automated microplate-reader at 630 nm. The limit of detection is 18-20 ng of gliotoxin in the well, depending on the used observation method. A high degree of specificity of the detection is brought about by the ability of the reducing reactant dithiothreitol to inhibit the biological activities of epipolythiodioxopiperazines (ETPs), such as gliotoxin, by reducing their polysulfide bridge. The bioassay allows a rapid primary screening of samples and a semi-quantitative evaluation of the gliotoxin concentration in extracts. The method has been used to study the gliotoxin production by different fungal strains, allowing to highlight 3 strains of Aspergillus fumigatus producing gliotoxin in various extracts.