Purification, molecular cloning, and characterization of glutathione S-transferases (GSTs) from pigmented Vitis vinifera L. cell suspension cultures as putative anthocyanin transport proteins

The ligandin activity of specific glutathione S-transferases (GSTs) is necessary for the transport of anthocyanins from the cytosol to the plant vacuole. Five GSTs were purified from Vitis vinifera L. cv. Gamay Fréaux cell suspension cultures by glutathione affinity chromatography. These proteins underwent Edman sequencing and mass spectrometry fingerprinting, with the resultant fragments aligned with predicted GSTs within public databases. The corresponding coding sequences were cloned, with heterologous expression in Escherichia coli used to confirm GST activity. Transcriptional profiling of these candidate GST genes and key anthocyanin biosynthetic pathway genes (PAL, CHS, DFR, and UFGT) in cell suspensions and grape berries against anthocyanin accumulation demonstrated strong positive correlation with two sequences, VvGST1 and VvGST4, respectively. The ability of VvGST1 and VvGST4 to transport anthocyanins was confirmed in the heterologous maize bronze-2 complementation model, providing further evidence for their function as anthocyanin transport proteins in grape cells. Furthermore, the differential induction of VvGST1 and VvGST4 in suspension cells and grape berries suggests functional differences between these two proteins. Further investigation of these candidate ligandins may identify a mechanism for manipulating anthocyanin accumulation in planta and in vitro suspension cells

DNA Metabarcoding to quantify the response of insect diversity to mountain forest die-offs in the French Pyrenees

Mountain forests suffer from an increase in frequency and severity of summer droughts and infestations of pathogens and insects. Those factors are causing high mortality of some keystone tree species (forest die-offs). Yet, how tree diebacks and associated changes in forest composition will affect local diversity and ecosystem functions remains unknown. Here, we aim at quantifying the impact of climate-induced forest decline on biodiversity by measuring changes in taxonomic structure of invertebrate communities along gradients of silver fir (Abies alba) dieback in the French Pyrenees. We use DNA metabarcoding to analyse 224 samples of Malaise traps placed on 56 silver fir dominated plots in the French Pyrenees from May to September 2017. Samples were sequenced using Illumina MiSeq and analysed using the DAMe twin-tagging pipeline approach. We conducted taxonomic assignment against reference DNA barcode libraries to streamli ne identification and recover biological information for ecological analysis. We discuss the results of our metabarcoding analysis and the utility of our approach to conduct biomonitoring across a large geographical scale

Climate-induced forest dieback drives compositional changes in insect communities that are more pronounced for rare species

Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly, most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions

Climate-induced forest dieback drives compositional changes in insect communities that are more pronounced for rare species

Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly, most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions

Evolutionary Progenitors of Bracoviruses

While viruses usually produce particles in the infected cells, polydnaviruses (PDVs) have a very unusual virus life-cycle. Particle production does not occur in infected tissues of parasitized caterpillars, but is restricted to specialized cells of the wasp ovary. The genome enclosed in the particles encodes almost no viral structural protein, but mostly virulence factors used to manipulate the physiology of the parasitized host. This lack of virus genes in the packaged genome has generated a debate on the viral nature of PDVs. The characterization of a hidden bracovirus genome composed of virus genes, residing permanently in the wasp chromosomes and producing the particles, confirmed that bracoviruses originated from a virus. The viral machinery is comprised of genes typical of nudiviruses, a sister group of baculoviruses. The conservation of nudiviral genes in the various lineages of braconid wasps associated with bracoviruses strongly suggests that their common ancestor acquired a nudivirus genome 100 million years ago, which still controls the production of particles during viral replicatio

Polydnavirus hidden face: The genes producing virus particles of parasitic wasps

International audienceVery few obligatory relationships involve viruses to the remarkable exception of polydnaviruses (PDVs) associated with tens of thousands species of parasitic wasps that develop within the body of lepidopteran larvae. PDV particles, injected along with parasite eggs into the host body, act by manipulating host immune defences, development and physiology, thereby enabling wasp larvae to survive in a potentially harmful environment. Particle production does not occur in infected tissues of parasitized caterpillars, but is restricted to specialized cells of the wasp ovaries. Moreover, the genome enclosed in the particles encodes almost no viral structural protein, but mostly factors used to manipulate the physiology of the parasitized host. We recently unravelled the viral nature of PDVs associated with braconid wasps by characterizing a large set of nudivirus genes residing permanently in the wasp chromosome(s). Many of these genes encode structural components of the bracovirus particles and their expression pattern correlates with particle production. They constitute a viral machinery comprising a large number of core genes shared by nudiviruses and baculoviruses. Thus bracoviruses do not appear to be nudiviruses remnants, but instead complex nudiviral devices carrying DNA for the delivery of virulence genes into lepidopteran hosts. This highlights the fact that viruses should no longer be exclusively considered obligatory parasites, and that in certain cases they are obligatory symbionts

Les polydnavirus : des virus qui pratiquent le transfert de gènes depuis 100 millions d’années

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Bracoviruses, ichnoviruses, and virus-like particles from parasitoid wasps retain many features of their virus ancestors

International audienceAnimal genomes commonly contain genes or sequences thathave been acquired from different types of viruses. The vastmajority of these endogenous virus elements (EVEs) areinactive or consist of only a small number of components thatshow no evidence of cooption for new functions or interaction.Unlike most EVEs, bracoviruses (BVs), ichnoviruses (IVs) andvirus-like particles (VLPs) in parasitoid wasps have evolvedthrough retention and interaction of many genes from virusancestors. Here, we discuss current understanding of BV, IVand VLP evolution along with associated implications for whatconstitutes a virus. We suggest that BVs and IVs aredomesticated endogenous viruses (DEVs) that differ in severalimportant ways from other known EVEs

Qualitative proteomic analysis of Tipula oleracea nudivirus occlusion bodies

Nudiviruses are arthropod-specific large double-stranded circular DNA viruses, related to baculoviruses, which replicate in the nucleus of the cells they infect. Up to date six fully sequenced nudiviral genomes are available in databases and protein profile from nudivirus particles were mainly characterized by polyacrylamide gel electrophoresis. However, only few direct matches were completed between genomic and proteomic data to the exception of the major occlusion body protein from Penaeus monodon nudivirus (PmNV) and four nucleocapsid proteins from Helicoverpa zea nudivirus 2 (HzNV-2). Function of predicted nudiviral proteins is still inferred from what is known from baculoviruses or endogenous nudiviruses (i.e. bracoviruses). Tipula oleracea nudivirus (ToNV) is the causative agent of crane fly nucleopolyhedrosis. With PmNV, ToNV is the second fully sequenced nudivirus to be described as forming occlusion bodies. Protein profile revealed by Coomassie-stained SDS-PAGE is quite similar to those observed for other nudiviruses with five major protein bands of about 75, 48, 35, 25 and 12 kDa. Proteomic analysis using on-line nanoflow liquid chromatography tandem high resolution mass spectrometry revealed ToNV occlusion bodies are composed of 52 viral proteins, the most abundant of which are the functional homolog of baculovirus polyhedrin/granulin and the homologs of three HzNV-2 predicted proteins: the two virion structural proteins 34K (Hz2V052, the baculovirus capsid protein VP39 homolog) and 11K (Hz2V025); and the hypothetical protein Hz2V079, a newly identified nudivirus core gene product