Host ethnicity and virus genotype shape the hepatitis B virus-specific T-cell repertoire

Repertoire composition, quantity, and qualitative functional ability are the parameters that define virus-specific T-cell responses and are linked with their potential to control infection. We took advantage of the segregation of different hepatitis B virus (HBV) genotypes in geographically and genetically distinct host populations to directly analyze the impact that host and virus variables exert on these virus-specific T-cell parameters. T-cell responses against the entire HBV proteome were analyzed in a total of 109 HBV-infected subjects of distinct ethnicities (47 of Chinese origin and 62 of Caucasian origin). We demonstrate that HBV-specific T-cell quantity is determined by the virological and clinical profiles of the patients, which outweigh any influence of race or viral diversity. In contrast, HBV-specific T-cell repertoires are divergent in the two ethnic groups, with T-cell epitopes frequently found in Caucasian patients seldom detected in Chinese patients. In conclusion, we provide a direct biological evaluation of the impact that host and virus variables exert on virus-specific T-cell responses. The discordance between HBV-specific CD8 T-cell repertoires present in Caucasian and Chinese subjects shows the ability of HLA micropolymorphisms to diversify T-cell responses and has implications for the rational development of therapeutic and prophylactic vaccines for worldwide use.     

Combined molecular and morphological data provide insights into the evolution and classification of Chilocorini ladybirds (Coleoptera: Coccinellidae)

Ladybirds of the cosmopolitan tribe Chilocorini prey mainly on coccids and include several important biocontrol agents. The phylogenetic relationships of Chilocorini are poorly known. In this paper, we provide a phylogenetic reconstruction of Chilocorini containing all 27 genera based on five molecular markers and 86 adult morphological characters. Morphological character states were mapped on the combined data tree from Bayesian inference to analyse morphological traits of each genus. Sixteen morphological characters were selected to reconstruct the ancestral states using maximum parsimony and maximum likelihood methods. Divergence times were estimated based on the relaxed molecular clock approach. Our results indicate that Chilocorini, excluding Chilocorellus Miyatake, is monophyletic and closely related to Plotinini. The crown group Chilocorini was estimated to date back to the Middle Cretaceous. Anisorcus Crotch, Egius Mulsant, Phaenochilus Weise and Simmondsius Ahmad & Ghani are synonymized here with Chilocorus Leach ( syn.n. ). The genus Chilocorellus is excluded from Chilocorini. The split of current genera was estimated to have occurred during the Middle Paleogene to Late Paleogene.     

Inferring the sources of postglacial range expansion in two large European land snails

Exact locations of glacial refugia are relevant for the study of contemporary biodiversity, not only as places less disturbed during the climatic changes but also as sources of rapid expansion of the biota after the Last Glacial cycle. If continuously inhabited over several of the Quaternary glacial cycles, the refugia are readily identifiable by the accumulated genetic diversity. However, the sources of the Holocene range expansion, particularly important for the emergence of present-day bio- and phylogeographic patterns and for realistic estimation of species’ expansion rates, might have been located at the fringes of the glacial species ranges and lack unique lineages. This problem is pertinent when the variation is explored at slowly evolving genetic markers. We suggest that the location of such source refugia may be approximated by reconstructing the geographic location as a continuous trait evolving along the branches of a phylogenetic tree. We applied this approach, using the BEAST software, on two large southeast European land snail species: Caucasotachea vindobonensis and Helix thessalica. We found evidence for C. vindobonensis refugia in the western Balkans; notable is an apparently old refugium in Bosnia and Herzegovina. The plausible sources of the species’ Holocene range expansion, however, were located around the south-western end of the Carpathians. Although the source areas were likely similar in H. thessalica, some expansion sources suggested by the analyses (e.g., Podolia, Ukraine) appeared implausible and driven by sampling clustered in that area. The applied approach allows for additional exploitation of the mitochondrial data gathered during the past two decades of animal phylogeography studies.     

Evolution of herbs: key to the conundrum might be tolerance not avoidance

草本植物的进化：解决难题的关键在于忍耐而非逃避 木本植物延续了其祖先被子植物的生长形态,而草本植物则不断地从中进化演变。虽然关于驱动草本植物习性进化的因素已有许多假设,但是通过舍弃地上生物质从而避免冬季冻害的能力常常被认为是促使其进化的主要力量。然而,鉴于草本植物在反复干扰中依旧能够轻松存活,我们提出了不可预测的干扰可能比季节性霜冻更为重要的假设。我们通过比较草本植物和木本植物应对3种模拟干扰(容易预测的冬季冰冻、不易预测的春季冰冻和食草作用)的能力来验证这一假设。通过比较20种不同植物在同质园实验中的表现,我们评估了这些干扰对植物死亡和再生方面的影响。研究结果表明,在冬季冰冻条件下,比起木本植物,草本植物在存活率上并没有优势。在不易预测的春季冰冻条件下,草本植物比木本植物的存活率更高。而在模拟食草作用的条件下,草本植物的这种生存优势更大。在不可预测的条件下,草本植物相较于木本植物的生存优势表明,草本植物的生长形式可能是对不可预测的干扰的适应,这种逆境忍耐通过其损失地上生物质也能够生存的能力得以实现。因此,哺乳动物的食草行为或火灾等原因或许最有可能是木本植物向草本植物过渡的因素。     

Spread and population structure of <Emphasis Type=Italic>Cryphonectria parasitica</Emphasis> in a young chestnut orchard in Slovakia

The chestnut blight pathogen Cryphonectria parasitica was studied in a chestnut collection composed of both seedlings and grafts derived from selected Castanea sativa and C. sativa × C. crenata trees located in south-east Slovakia, near village Príbelce on an area of approximately 3.5 ha. The study was conducted during eight years (2003–2010). During this period 133 trees were infected, which represents 59.82% of chestnut trees of all chestnut accessions. Based on the phenotype of the fungus culture and the type of cankers in the field, all isolates were determined to be virulent. No hypovirulent strains were found. No vegetative compatibility (vc) type diversity was observed. More than 130 isolates were analyzed for vc and all were in single vc type, which was identical with EU 12. All isolates assayed for mating type were MAT-1. No perithecia were observed. No significant differences were found between the proportion of cankered and dead cankered trees in seedlings and grafts of hybrid origin (C. sativa × C. crenata) and of C. sativa origin. However, particular seedlings and grafts of hybrid origin seemed to exhibit certain resistance to chestnut blight.     

Identification and Characterisation of the RalA-ERp57 Interaction: Evidence for GDI Activity of ERp57

RalA is a membrane-associated small GTPase that regulates vesicle trafficking. Here we identify a specific interaction between RalA and ERp57, an oxidoreductase and signalling protein. ERp57 bound specifically to the GDP-bound form of RalA, but not the GTP-bound form, and inhibited the dissociation of GDP from RalA in vitro. These activities were inhibited by reducing agents, but no disulphide bonds were detected between RalA and ERp57. Mutation of all four of ERp57’s active site cysteine residues blocked sensitivity to reducing agents, suggesting that redox-dependent conformational changes in ERp57 affect binding to RalA. Mutations in the switch II region of the GTPase domain of RalA specifically reduced or abolished binding to ERp57, but did not block GTP-specific binding to known RalA effectors, the exocyst and RalBP1. Oxidative treatment of A431 cells with H₂O₂ inhibited cellular RalA activity, and the effect was exacerbated by expression of recombinant ERp57. The oxidative treatment significantly increased the amount of RalA localised to the cytosol. These findings suggest that ERp57 regulates RalA signalling by acting as a redox-sensitive guanine-nucleotide dissociation inhibitor (RalGDI).     

Primordial Enemies: Fungal Pathogens in Thrips Societies

Microbial pathogens are ancient selective agents that have driven many aspects of multicellular evolution, including genetic, behavioural, chemical and immune defence systems. It appears that fungi specialised to attack insects were already present in the environments in which social insects first evolved and we hypothesise that if the early stages of social evolution required antifungal defences, then covariance between levels of sociality and antifungal defences might be evident in extant lineages, the defences becoming stronger with group size and increasing social organisation. Thus, we compared the activity of cuticular antifungal compounds in thrips species (Insecta: Thysanoptera) representing a gradient of increasing group size and sociality: solitary, communal, social and eusocial, against the entomopathogen Cordyceps bassiana. Solitary and communal species showed little or no activity. In contrast, the social and eusocial species killed this fungus, suggesting that the evolution of sociality has been accompanied by sharp increases in the effectiveness of antifungal compounds. The antiquity of fungal entomopathogens, demonstrated by fossil finds, coupled with the unequivocal response of thrips colonies to them shown here, suggests two new insights into the evolution of thrips sociality: First, traits that enabled nascent colonies to defend themselves against microbial pathogens should be added to those considered essential for social evolution. Second, limits to the strength of antimicrobials, through resource constraints or self-antibiosis, may have been overcome by increase in the numbers of individuals secreting them, thus driving increases in colony size. If this is the case for social thrips, then we may ask: did antimicrobial traits and microbes such as fungal entomopathogens play an integral part in the evolution of insect sociality in general?