Project description:During the Late Pleistocene, narrow-headed voles (Lasiopodomys gregalis) inhabited Eurasia's vast territories, frequently becoming the dominant small mammal species among steppe-tundra communities. We investigated the relationship between this species' European and Asiatic populations by sequencing the mtDNA genomes of two extant specimens from Russia and 10 individuals from five Central European sites, dated to the post-LGM period. Phylogenetic analyses based on a large portion of mtDNA genomes highly supported the positioning of L. gregalis within Arvicolinae. The phylogeny based on mtDNA cytochrome b sequences revealed a deep divergence of European narrow-headed voles from Asiatic ones and their sister position against the extant L. gregalis and L. raddei. The divergence of the European lineage was estimated to a minimum 230 thousand years ago. This suggest, contrary to the current biogeographic hypotheses, that during the interglacial periods narrow-headed vole did not retreat from Europe but survived the unfavourable conditions within the refugial areas. Based on this result, we propose to establish a cryptic species status for the Late Pleistocene European narrow-headed vole and to name this taxon Lasiopodomys anglicus.
Project description:An Infinium microarray platform (GPL28271, HorvathMammalMethylChip40) was used to generate DNA methylation data from several tissues from prairie voles (Microtus ochrogaster). Ear, liver, and brain samples from the Cornell University prairie vole colony were collected from 48 male and female prairie voles at various life stages: neonatal (<1 month old), sub-adult (2-4 months old), mature adult (4-10 months old), and middle aged/old adult (>10 months old). The pair bonded male and female prairie voles used in our study cohabitated with their partners for several months and produced at least three generations of litters. Animals were euthanized via rapid decapitation, their tissues rapidly extracted and frozen on dry ice before being stored at -80C until further processing for genomic DNA extraction. Brains were coronally sectioned and brain regions from the pair bonding circuit (PBC) were micro-dissected and pooled for each animal. The PBC brain regions included the prefrontal cortex, nucleus accumbens, lateral septum, ventral pallidum, and medial amygdala, and ventral tegmental area. Genomic DNA was isolated and purified using the phenol-chloroform extraction and ethanol precipitation method. A total of 144 tissue samples were collected and processed for DNA methylation analysis. Tissues: Brain, Ear, Liver
Project description:The late Pleistocene witnessed the extinction of 35 genera of North American mammals. The last appearance dates of 16 of these genera securely fall between 12,000 and 10,000 radiocarbon years ago (approximately 13,800-11,400 calendar years B.P.), although whether the absence of fossil occurrences for the remaining 19 genera from this time interval is the result of sampling error or temporally staggered extinctions is unclear. Analysis of the chronology of extinctions suggests that sampling error can explain the absence of terminal Pleistocene last appearance dates for the remaining 19 genera. The extinction chronology of North American Pleistocene mammals therefore can be characterized as a synchronous event that took place 12,000-10,000 radiocarbon years B.P. Results favor an extinction mechanism that is capable of wiping out up to 35 genera across a continent in a geologic instant.
Project description:The mouse anterior-posterior (A-P) axis polarization is preceded by formation of the distal visceral endoderm (DVE). However, the mechanism of the emergence of DVE cells is not well understood. Here, we show by in vitro culturing of embryos immediately after implantation in micro-fabricated cavities (narrow; 90 micro-meter, wide; 180 miro-meter in diameter) that the external mechanical cues exerted on the embryo, i.e. cultured in the narrow cavity, are crucial for DVE formation as well as elongated egg cylinder shape. This implies that these developmental events immediately after implantation are not simply embryo-autonomous processes but require extrinsic mechanical factors. Further whole genome-wide gene expression profiles with DNA microarray revealed that no significant difference of transcripts were evident with or without mechanical cues except DVE-related markers. Thus, we propose that external mechanical cues rather than not specific molecular pathways can trigger the establishment of the A-P axis polarization, which is one of the fundamental proccesses of mammalian embryogenesis. To identify the differences between the embryos cultured with or without external mechanical cues, we collected mouse embryos at E5.0 and cultured in the narrow (90 micro-meter in diameter) or the wide (180 micro-meter in diameter) cavities for 8 hours for RNA extraction and hybridization on Affymetrix microarrays. Arrays were performed using Affymetrix mouse Gene 1.0 ST arrays. Analysis was performed on three biological replicates of the mouse embryos cultured in the narrow and wide cavities for 8 hours.
Project description:The importance of fathers' engagement in care and its critical role in the offspring’s cognitive and emotional development is now well established. Yet, little is known on the underlying neurobiology due to the lack of appropriate animal models. In the socially monogamous and bi-parental prairie vole (Microtus ochrogaster), while most virgin males show spontaneous paternal behaviors (Paternal), others display pup-directed aggression (Attackers). Here we took advantage of this phenotypic dichotomy and used RNA-sequencing in three important brain areas to characterize gene expression associated with paternal behaviors of Paternal males and compare it to experienced fathers and mothers. This strategy allowed the identification of spontaneous paternal behaviors independently from fatherhood and pair-bonding. While Paternal males displayed the same range and extent of paternal behaviors than experienced Fathers, the nucleus accumbens (NAc) and medial preoptic area (MPOA) transcriptomes mainly reflected pair-bonded status or sex differences, respectively. The lateral septum (LS) transcriptome, however, primarily reflected phenotypic differences between Paternal and Attackers and suggested the involvement of the mitochondria, RNA translation, and protein degradation processes. Altogether, these observations highlight a marked structure- and phenotype-specific pattern of gene expression underlying paternal behaviors in prairie voles and highlight similarities and differences from those underlying fatherhood.
Project description:Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an ~9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an ~33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled dogs. We detected gene flow from Pleistocene Siberian wolves, but not modern American wolves, to present-day sled dogs. The results indicate that the major ancestry of modern sled dogs traces back to Siberia, where sled dog-specific haplotypes of genes that potentially relate to Arctic adaptation were established by 9500 years ago.