Germline DNA copy number variation in individuals with Argyrophilic grain disease reveals CTNS as a plausible candidate gene

Argyrophilic grain disease (AGD) is a progressive neurodegenerative disease of the human brain that has never been associated to a particular gene locus. In the present study, we report the results of a CNV investigation in 29 individuals whose anatomopathologic investigation of the brain showed AGD. Rare CNVs were identified in six patients (21%), in particular a 40 kb deletion at 17p13.2 encompassing the CTNS gene. Homozygote mutations in CTNS are known to cause cystinosis, a disorder characterized by the intralysosomal accumulation of cystine in all tissues. We present the first CNV results in individuals presenting AGD and a possible candidate gene implicated in the disorder.     

Life history trade‐offs and evidence for hierarchical resource allocation in two monocarpic perennials

The evolution of floral display is thought to be constrained by trade‐offs between the size and number of flowers; however, empirical evidence for the trade‐off is inconsistent. We examined evidence for trade‐offs and hierarchical allocation of resources within and between two populations each of the monocarpic perennials, Cardiocrinum cordatum and C. giganteum. Within all populations, flower size–number trade‐offs were evident after accounting for variation in plant size. In addition, variation in flower size explained much variation in flower‐level allocation to attraction, and female and male function, a pattern consistent with hierarchical allocation. However, between population differences in flower size (C. cordatum) and number (C. giganteum) were not consistent with size–number trade‐offs or hierarchical allocation. The population‐level difference in C. cordatum likely reflects the combined influence of a time lag between initiation and maturation of flowers, and higher light levels in one population. Thus, our study highlights one mechanism that may account for the apparent independence of flower size and number in many studies. A prediction of sex allocation theory was also supported. In C. giganteum: plants from one population invested more mass in pistils and less in stamens than did plants from the other population. Detection of floral trade‐offs in Cardiocrinum may be facilitated by monocarpic reproduction, production of a single inflorescence and ease of measuring plant size.     

Hyaluronic acid degradation during initial steps of downstream processing

Abstract

Hyaluronic acid (HA) is a linear glycosaminoglycan composed of disaccharide units of glucuronic acid and N-acetylglucosamine. It has interesting and distinctive viscoelastic properties that are functions of chain length, concentration and environmental conditions, like pH and ionic strength. These characteristics, coupled with its lack of immunogenicity or toxicity, have led to a wide range of applications in the pharmaceutical and cosmetic industries where molecular mass is of primary importance. Biotechnological production of HA was established many years ago, but HA obtained from bacterial fermentation results in shorter chains compared with HA extracted from animal sources. In the present research the issue of HA degradation during the initial phases of downstream processing is addressed. In particular, the effects of clarification and protein separation on molecular weight have been studied using a triple-detector chromatographic system. Environmental factors affecting degradation (pH, shear stresses, etc.) were uncoupled in order to identify the main causes of molecular weight reduction.     

头足类角质颚地标点定量初步研究： 以剑尖枪乌贼为例

几何形态测量学是头足类角质颚形态分析的重要研究方法,其中包括地标点法和轮廓线法。虽然地标点类型被划分为三种,但基于地标点法的角质颚形态研究对于地标点的选取与建立并没有一个统一的标准,因此探究可以更好地展示角质颚形态变异程度所需要的地标点以及样本数是十分必要的。为探究不同地标点和样本数对角质颚形态分析的影响,本研究利用2018和2019年捕捞的剑尖枪乌贼(Uroteuthis edulis)角质颚样本,使用R语言LaMBDA包LaSEC函数,对300对角质颚样本分别使用10、20、28个地标点和50、80、100、200、300对样本组合,以探讨不同地标点和样本数方案时表示形态变异的平稳度。研究结果表明,地标点数量会使质心大小结果产生误差;为了更好地展示角质颚的形态变异程度,最终确定研究样本在50对以内时,上颚和下颚采用26个地标点;研究样本为50～300对时采用27个地标点。研究分析认为,基于LaSEC的头足类角质颚地标点和样本定量分析可以拟定表示角质颚形态变异的最佳地标点数量,并通过角质颚形态变异箭头图来明确表示角质颚形态变异的最佳地标点方案,为后续基于地标点法的头足类角质颚形态研究提供科学依据。     

Alternative transmission pathways for guinea worm in dogs: implications for outbreak risk and control

Guinea worm (Dracunculus medinensis) has exerted a high human health burden in parts of Africa. Complete eradication of Guinea worm disease (dracunculiasis) may be delayed by the circulation of the parasite in domestic dogs. As with humans, dogs acquire the parasite by directly ingesting infected copepods, and recent evidence suggests that consuming frogs that ingested infected copepods as tadpoles may be a viable transmission route (paratenic route). To understand the relative contributions of direct and paratenic transmission routes, we developed a mathematical model that describes transmission of Guinea worm between dogs, copepods and frogs. We explored how the parasite basic reproductive number (R₀) depends on parameters amenable to actionable interventions under three scenarios: frogs/tadpoles do not consume copepods; tadpoles consume copepods but frogs do not contribute to transmission; and frogs are paratenic hosts. We found a non-monotonic relationship between the number of dogs and R₀. Generally, frogs can contribute to disease control by removing infected copepods from the waterbody even when paratenic transmission can occur. However, paratenic transmission could play an important role in maintaining the parasite when direct transmission is reduced by interventions focused on reducing copepod ingestion by dogs. Together, these suggest that the most effective intervention strategies may be those which focus on the reduction of copepods, as this reduces outbreak potential irrespective of the importance of the paratenic route.     

Bias in vegetation databases? A comparison of stratified‐random and preferential sampling

Aim: Vegetation plots collected since the early 20th century and stored in large vegetation databases are an important source of ecological information. These databases are used for analyses of vegetation diversity and estimation of vegetation parameters, however such analyses can be biased due to preferential sampling of the original data. In contrast, modern vegetation survey increasingly uses stratified‐random instead of preferential sampling. To explore how these two sampling schemes affect vegetation analyses, we compare parameters of vegetation diversity based on preferentially sampled plots from a large vegetation database with those based on stratified‐random sampling. Location: Moravian Karst and Silesia, Czech Republic. Methods: We compared two parallel analyses of forest vegetation, one based on preferentially sampled plots taken from a national vegetation database and the other on plots sampled in the field according to a stratified‐random design. We repeated this comparison for two different regions in the Czech Republic. We focussed on vegetation properties commonly analysed using data from large vegetation databases, including alpha (within‐plot) diversity, cover and participation of different species groups, such as endangered and alien species within plots, total species richness of data sets, beta diversity and ordination patterns. Results: The preferentially sampled data sets obtained from the database contained more endangered species and had higher beta diversity, whereas estimates of alpha diversity and representation of alien species were not consistently different between preferentially and stratified‐randomly sampled data sets. In ordinations, plots from the preferential samples tended to be more common at margins of plot scatters. Conclusions: Vegetation data stored in large databases are influenced by researcher subjectivity in plot positioning, but we demonstrated that not all of their properties necessarily differ from data sets obtained by stratified‐random sampling. This indicates the value of vegetation databases for use in biodiversity studies; however, some analyses based on these databases are clearly biased and their results must be interpreted with caution.     

Origin of the 1918 pandemic H1N1 influenza A virus as studied by codon usage patterns and phylogenetic analysis

The pandemic of 1918 was caused by an H1N1 influenza A virus, which is a negative strand RNA virus; however, little is known about the nature of its direct ancestral strains. Here we applied a broad genetic and phylogenetic analysis of a wide range of influenza virus genes, in particular the PB1 gene, to gain information about the phylogenetic relatedness of the 1918 H1N1 virus. We compared the RNA genome of the 1918 strain to many other influenza strains of different origin by several means, including relative synonymous codon usage (RSCU), effective number of codons (ENC), and phylogenetic relationship. We found that the PB1 gene of the 1918 pandemic virus had ENC values similar to the H1N1 classical swine and human viruses, but different ENC values from avian as well as H2N2 and H3N2 human viruses. Also, according to the RSCU of the PB1 gene, the 1918 virus grouped with all human isolates and "classical" swine H1N1 viruses. The phylogenetic studies of all eight RNA gene segments of influenza A viruses may indicate that the 1918 pandemic strain originated from a H1N1 swine virus, which itself might be derived from a H1N1 avian precursor, which was separated from the bulk of other avian viruses in toto a long time ago. The high stability of the RSCU pattern of the PB1 gene indicated that the integrity of RNA structure is more important for influenza virus evolution than previously thought.     

Adjustment of sperm allocation under high risk of sperm competition across taxa: a meta-analysis

Sperm competition theory predicts that under high risk of sperm competition, males will increase the number of sperm that they allocate to a female. This prediction has been supported by some experimental studies but not by others. Here, I conducted a meta-analysis to determine whether the increase in sperm allocation under high risk of sperm competition is a generalized response across taxa. I collected data from 39 studies and 37 species. Across taxa, males under a high risk of sperm competition respond by increasing their sperm allocation (mean effect size=0.32). Number of offspring did not explain a significant portion of the variation in effect sizes. A traditional meta-analysis (i.e. without phylogenetic information) described the variation among effect sizes better than a meta-analysis that incorporates the phylogenetic relationships among species, suggesting that the increase in sperm allocation under high risk of sperm competition is similarly prevalent across taxa.