Project description:The Formosan subterranean termite (Coptotermes formosanus) and the Asian subterranean termite (Coptotermes gestroi) are the most destructive termite pests in the world. Both species have spread to various regions worldwide with overlapping distributions in a few areas in which pre- and post-zygotic barriers against hybridization between the two species have been lifted. Although initial colony growth rates of hybrid colonies are similar to those of the parental species, colony growth appears to slow down in the hybrids after several years. Observations suggest that workers in hybrid colonies are slower to molt than those of the parental species, suggesting a disruption in this process. To understand the comprehensive gene expression profiles during the molting cycle of workers, differential gene expression profiles based on RNA-seq analysis were recorded for four mating combinations (2 conspecific workers and 2 heterospecific workers) at three different molting periods (pre-, post- and inter-molt). Many differentially expressed genes were identified between heterospecific and conspecific matings at each molting stage as well as within termite species among molting periods. We successfully identified molting-related genes by characterizing gene expression profiles of the parental species during the molting cycle conducting a time course analysis of transcriptome data. We then compared expression levels of these molting-related genes in the hybrids to identify genes that were over or under expressed compared to the parental species. Genes related to the molting cycle, muscle contraction, response to stress, and ecdysone metabolism were found to be under-expressed in hybrids relative to their parents. These differences will help elucidate the stability and fitness of hybrids between these two Coptotermes species. Moreover, identification of molting related genes in subterranean termites highlights the molecular pathways involved in the molting process in termites.

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.

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