VSGdb: a database for trypanosome variant surface glycoproteins,a large and diverse family of coiled coil proteins

Background  

Trypanosomes are coated with a variant surface glycoprotein (VSG) that is so densely packed that it physically protects underlying proteins from effectors of the host immune system. Periodically cells expressing a distinct VSG arise in a population and thereby evade immunity. The main structural feature of VSGs are two long α-helices that form a coiled coil, and sets of relatively unstructured loops that are distal to the plasma membrane and contain most or all of the protective epitopes. The primary structure of different VSGs is highly variable, typically displaying only ~20% identity with each other. The genome has nearly 2000 VSG genes, which are located in subtelomeres. Only one VSG gene is expressed at a time, and switching between VSGs primarily involves gene conversion events. The archive of silent VSGs undergoes diversifying evolution rapidly, also involving gene conversion. The VSG family is a paradigm for α helical coiled coil structures, epitope variation and GPI-anchor signals. At the DNA level, the genes are a paradigm for diversifying evolutionary processes and for the role of subtelomeres and recombination mechanisms in generation of diversity in multigene families. To enable ready availability of VSG sequences for addressing these general questions, and trypanosome-specific questions, we have created VSGdb, a database of all known sequences.     

Molecular-based estimate of species number,phylogenetic relationships and divergence times for the genus Stenotaenia (Chilopoda,Geophilomorpha) in the Italian region

Stenotaenia is one of the largest and most widespread genera of geophilid centipedes in the Western Palearctic, with a very uniform morphology and about fifteen species provisionally recognized. For a better understanding of Stenotaenia species-level taxonomy, we have explored the possibility of using molecular data. As a preliminary assay, we sampled twelve populations, mainly from the Italian region, and analyzed partial sequences of the two genes COI and 28S. We employed a DNA-barcoding approach, complemented by a phylogenetic analysis coupled with divergence time estimation. Assuming a barcoding gap of 10–16% K2P pairwise distances, we found evidence for the presence of at least six Stenotaenia species in the Italian region, which started diverging about 50 million years ago, only partially matching with previously recognized species. We found that small-sized oligopodous species belong to a single clade that originated about 33 million years ago, and obtained some preliminary evidence of the related genus Tuoba being nested within Stenotaenia.     

Effects of heat and UV radiation on the mobilization of transposon mariner-Mos1

There are many complex interactions between transposable elements (TEs) and host genomes. Environmental changes that induce stressful conditions help to contribute for increasing complexity of these interactions. The transposon mariner-Mos1 increases its mobilization under mild heat stress. It has putative heat shock elements (HSEs), which are probably activated by heat shock factors (HSFs). Ultraviolet radiation (UVC) is a stressor that has been suggested as able to activate heat shock protein genes (Hsp). In this study, we test the hypothesis that if UVC induces Hsp expression, as heat does, it could also promote mariner-Mos1 transposition and mobilization. The Drosophila simulans white-peach is a mutant lineage that indicates the mariner-Mos1 transposition phenotypically through the formation of mosaic eyes. This lineage was exposed to UVC or mild heat stress (28 °C) in order to evaluate the induction of mariner-Mos1 expression by RT-qPCR, as well as the mariner-Mos1 mobilization activity based on the count number of red spots in the eyes. The effects of both treatments on the developmental time of flies and cell cycle progression were also investigated. Both the analysis of eyes and mariner-Mos1 gene expression indicate that UVC radiation has no effect in mariner-Mos1 transposition, although heat increases the expression and mobilization of this TE soon after the treatment. However, the expression of Hsp70 gene increased after 24 h of UVC exposure, suggesting different pathway of activation. These results showed that heat promotes mariner-Mos1 mobilization, although UVC does not induce the expression or mobilization of this TE.

Electronic supplementary material

The online version of this article (doi:10.1007/s12192-015-0611-2) contains supplementary material, which is available to authorized users.     

New C-23 modified of silybin and 2,3-dehydrosilybin: synthesis and preliminary evaluation of antioxidant properties

Silybin is the major flavonolignan of silymarin and it displays a plethora of biological effects, generally ascribed to its antioxidant properties. Herein we shall describe an efficient synthetic strategy to obtain a variety of new and more water-soluble silybin and 2,3-dehydrosilybin (DHS) derivatives in which the 23-hydroxyl group was converted to a sulfate, phosphodiester, or amine group, using a solution-phase approach. Furthermore a new and efficient method for the preparation of DHS from silybin was developed and optimised.The antioxidant properties of the new compounds were evaluated in a cellular model in vivo and they displayed an antioxidant activity comparable to or higher than silybin and DHS, being able to prevent H₂O₂-induced generation of intracellular reactive oxygen species (ROS). Most of the derivatives also displayed a better hydrophilicity while retaining the biological activities of silybin and they might broaden the in vivo applications of this class of natural compounds.     

Identification and expression of soul/p22HBP genes in zebrafish

The SOUL/p22HBP family is an evolutionarily ancient group of heme binding proteins with a main function as cytosolic buffer against tetrapyrrole accumulation. Structural and biochemical evidence suggest specialized roles in blood formation, necrotic cell death and chemotaxis. To date, nothing is known about the precise activity and expression patterns of this class of heme binding proteins during development. The zebrafish genome possesses five soul genes belonging to two subgroups, and no p22HBP orthologous gene. Here, spatial and temporal expression patterns are reported for zebrafish soul1, soul2 and soul4 genes. All three soul genes are maternally transcribed, and their zygotic expression takes place in unique (heart, pharynx, yolk syncytial layer, brain, eyes, lateral line) and overlapping (pronephros, pituitary gland, olfactory and otic vesicle) regions of the zebrafish embryo. Our study constitutes the first detailed analysis of soul gene expression in metazoan development, and provides the basis to understand the genetics of tetrapyrrole metabolism in a wide range of embryonic processes.