Project description:The naked mole-rat (NMR; Heterocephalus glaber) has recently gained considerable attention in the scientific community for its unique potential to unveil novel insights in the fields of medicine, biochemistry, and evolution. NMRs exhibit unique adaptations that include protracted fertility, cancer resistance, eusociality, and anoxia. This suite of adaptations is not found in other rodent species, suggesting that interrogating conserved and accelerated regions in the NMR genome will find regions of the NMR genome fundamental to their unique adaptations. However, the current NMR genome assembly has limits that make studying structural variations, heterozygosity, and non-coding adaptations challenging. We present a complete diploid naked-mole rat genome assembly by integrating long-read and 10X-linked read genome sequencing of a male NMR and its parents, and Hi-C sequencing in the NMR hypothalamus (N=2). Reads were identified as maternal, paternal or ambiguous (TrioCanu). We then polished genomes with Flye, Racon and Medaka. Assemblies were then scaffolded using the following tools in order: Scaff10X, Salsa2, 3d-DNA, Minimap2-alignment between assemblies, and the Juicebox Assembly Tools. We then subjected the assemblies to another round of polishing, including short-read polishing with Freebayes. We assembled the NMR mitochondrial genome with mitoVGP. Y chromosome contigs were identified by aligning male and female 10X linked reads to the paternal genome and finding male-biased contigs not present in the maternal genome. Contigs were assembled with publicly available male NMR Fibroblast Hi-C-seq data (SRR820318). Both assemblies have their sex chromosome haplotypes merged so that both assemblies have a high-quality X and Y chromosome. Finally, assemblies were evaluated with Quast, BUSCO, and Merqury, which all reported the base-pair quality and contiguity of both assemblies as high-quality. The assembly will next be annotated by Ensembl using public RNA-seq data from multiple tissues (SRP061363). Together, this assembly will provide a high-quality resource to the NMR and comparative genomics communities.

Project description:To identify genes that are downstream of gonadal hormones and that control dimorphic behaviors, we used a MEEBO array platform to profile gene expression of adult male and female hypothalamus against a whole brain reference sample. The experimental design allowed us to identify genes that are upreguated in the hypothalamus compared to the whole brain and are dimorphically expressed between the two sexes. In situ hybridization of candiate genes were carried out to validate the dimorphic expression of these genes in the hypothalamus. Array results were used to create a list of genes to screen by in situ hybridization. For each normalization method, a list of genes that were upregulated in the male or the female was created, and a gene had to be on a set number of these individual normalization lists in order to be considered for screening. A similar method was used to create a list of hypothalamic upregulated genes. The final screening list was comprised of genes that were upregulated in the male or female as well as in the hypothalamus. If in situ hybridization proved that the gene was upregulated in the male or female brain, we concluded that that transcript was differentially expressed. No one normalization method was weighted over another, and the array results were used to create a screening list for in situ hybridizations. Hypothalami from 4 adult animals of each sex were microdissected and pooled for each experimental sample and the whole brain plus pituitary from one male and one female were pooled to provide the reference sample. Each set of samples (male and female) was hybridized to two arrays to provide two technical replicates for each set of samples taken. A total of three sets of samples were taken (three biological replicates). For the "_amp" Samples, source (hypothalamus and whole brain) mRNA was amplified using T7 based method. For this set, data were not normalized, rather the raw intensities were used to calculate ratios. Candidate genes from this study was also included in final list in situ screening.

Project description:The naked mole-rat (NMR; Heterocephalus glaber) has recently gained considerable attention in the scientific community for its unique potential to unveil novel insights in the fields of medicine, biochemistry, and evolution. NMRs exhibit unique adaptations that include protracted fertility, cancer resistance, eusociality, and anoxia. This suite of adaptations is not found in other rodent species, suggesting that interrogating conserved and accelerated regions in the NMR genome will find regions of the NMR genome fundamental to their unique adaptations. However, the current NMR genome assembly has limits that make studying structural variations, heterozygosity, and non-coding adaptations challenging. We present a complete diploid naked-mole rat genome assembly by integrating long-read and 10X-linked read genome sequencing of a male NMR and its parents, and Hi-C sequencing in the NMR hypothalamus (N=2). Reads were identified as maternal, paternal or ambiguous (TrioCanu). We then polished genomes with Flye, Racon and Medaka. Assemblies were then scaffolded using the following tools in order: Scaff10X, Salsa2, 3d-DNA, Minimap2-alignment between assemblies, and the Juicebox Assembly Tools. We then subjected the assemblies to another round of polishing, including short-read polishing with Freebayes. We assembled the NMR mitochondrial genome with mitoVGP. Y chromosome contigs were identified by aligning male and female 10X linked reads to the paternal genome and finding male-biased contigs not present in the maternal genome. Contigs were assembled with publicly available male NMR Fibroblast Hi-C-seq data (SRR820318). Both assemblies have their sex chromosome haplotypes merged so that both assemblies have a high-quality X and Y chromosome. Finally, assemblies were evaluated with Quast, BUSCO, and Merqury, which all reported the base-pair quality and contiguity of both assemblies as high-quality. The assembly will next be annotated by Ensembl using public RNA-seq data from multiple tissues (SRP061363). Together, this assembly will provide a high-quality resource to the NMR and comparative genomics communities.

Dataset Information

Chromatin accessibility in the adult male and female naked mole rat hypothalamus before and during colony removal

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