Project description:Perkinsus marinus is an intracellular parasitic protozoan that is responsible for serious disease epizootics in marine bivalve molluscs worldwide and along with P. olseni belongs to the OIE list of notified diseases. Despite all available information on P. marinus genomics, more baseline data is required at the proteomic level for a better understanding of P. marinus biological processes, including virulence mechanisms. In the present study, we have established in vitro clonal cultures of P. marinus from infected gills and mantle tissues of C. rhizophorae to evaluate the parasite cellular proteomic profile. A high throughput label-free shotgun HDMS approach using nanoUPLC-MS was used. Our intention was to provide the first comprehensive proteome profile of P. marinus that might serve as a valuable resource for future investigations involving comparative analyses of P. marinus from different regions, as well as comparisons of different species of Perkinsus.
Project description:In this study, we explored the metabolic processes of P. marinus under lipid deprived conditions to elucidate the interchanging flux of lipid and carbohydrate metabolism. Though P. marinus can synthesize their own lipids from available nutrients, they display a slower growth in media not supplemented with lipids as opposed to media with lipids. Under these conditions, using transcriptomics, we surprisingly observed evidence of stimulated lipid degradation through increased transcription of two core β-oxidation pathway enzymes.
Project description:A major challenge of modern biology is to understand how naturally occurring variation in DNA sequences affects complex organismal phenotypes through networks of intermediate molecular phenotypes. Here, we performed deep RNA sequencing of 200 Drosophila Genetic Reference Panel inbred lines with complete genome sequences and mapped expression quantitative trait loci for annotated genes, novel transcribed regions (most of which are long noncoding RNAs), transposable elements and microbial species. We identified host variants affecting expression of transposable elements independent of copy number and microbiome composition. We constructed sex-specific expression quantitative trait locus regulatory networks. These networks are enriched for novel transcribed regions and target genes in heterochromatin and euchromatic regions of reduced recombination and are associated with transposable element expression. This study uncovers novel genetic features that regulate natural genetic variation of gene expression and generates testable hypotheses for future functional analyses.
Project description:Genome-wide DNA methylation mapping uncovers epigenetic changes associated with animal development, environmental adaptation, and species evolution. To address the lack of high-throughput methods for studying DNA methylation in non-model organisms, we developed an integrated approach for studying DNA methylation differences without a reference genome. Experimentally, our method relies on an optimized 96-well protocol for reduced representation bisulfite sequencing (RRBS), which we have validated in nine species (human, mouse, rat, cow, dog, chicken, zebrafish, carp, and sea bass). Bioinformatically, we developed the RefFreeDMA software (http://RefFreeDMA.computational-epigenetics.org) to deduce ad hoc genomes directly from RRBS reads and to pinpoint differentially methylated regions. These regions are interpreted using motif enrichment analysis and/or cross-mapping to annotated genomes. We validated our method by reference-free analysis of cell type-specific DNA methylation in the blood of human, cow, and carp. In summary, we present a cost-effective method for epigenome analysis in ecology and evolution, which enables epigenome-wide association studies in natural populations and species without a reference genome.
Project description:Here, we present the results of an integrative study that leverages naturally segregating variation and a recent, adaptive divergence event affecting seasonal timing to identify developmental mechanisms underlying diapause progression in a tephritid fly, Rhagoletis pomonella. Also called the apple maggot fly, R. pomonella is native to North America, where it infests fruits of native Crataegus (hawthorn) species throughout its range. Derived populations of the fly infest apples (Malus domesticus), and thus have evolved in the last ~250 years since apples were introduced. Many molecular studies in conjunction with mark-recapture experiments document that the populations, or host races, remain genetically distinct despite ongoing gene flow, making R. pomonella a textbook example of incipient speciation with gene flow and host associated divergence. Strong natural selection on two primary traits, host finding behavior and seasonal timing, maintain genetic divergence. Both populations (hereafter apple and haw flies) have one generation per year, with a functionally obligate pupal diapause, overwintering in the soil. Adults must emerge coincident with host fruit availability, typically a period of only a few weeks, in order to successfully oviposit into fruits. Apple flies have evolved an earlier (~3 week) emergence timing to synchronize with apples, which fruit about 3 weeks earlier than hawthorn at a typical, sympatric site in the Midwest (e.g., Michigan or Illinois, USA). We combined RNA sequencing (RNAseq), phenotyping of emergence timing and brain morphology, and whole genome pooled resequencing (Poolseq) to infer mechanisms underlying segregating variation for diapause phenology in each Rhagoletic pomonella host race, and the evolved difference in phenology between host races.