Genome sequencing of naked mole-rat in Kumamoto University
Ontology highlight
ABSTRACT: This project determine the genome sequence of Naked mole rat in Kumamoto University, and detected the intra-specific variation of genomes in this species.
Project description:Background Mouse and rat models are mainstays in pharmacology, toxicology and drug development – but differences between strains and between species complicate data interpretation and application to human health. Dioxin-like polyhalogenated aromatic hydrocarbons represent a major class of environmentally and economically relevant toxicants. In mammals dioxin exposure leads to a broad spectrum of adverse affects, including hepatotoxicity of varying severity. Several studies have shown that dioxins extensively alter hepatic mRNA levels. Surprisingly, though, analysis of a limited portion of the transcriptome revealed that rat and mouse responses diverge greatly (Boverhof et al. Toxicol Sci 94:398–416, 2006). Results We employed oligonucleotide arrays to compare the response of 8,125 rat and mouse orthologs. We confirmed that there is limited inter-species overlap in dioxin-responsive genes. Rat-specific and mouse-specific genes are enriched for specific functional groups which differ between species, conceivably accounting for species-specificities in liver histopathology. While no evidence for the involvement of copy-number variation was found, extensive inter-species variation in the transcriptional-regulatory network was identified; Nr2f1 and Fos emerged as candidates to explain species-specific and species-independent responses, respectively. Conclusion Our results suggest that a small core of genes is responsible for mediating the similar features of dioxin hepatotoxicity in rats and mice but non-overlapping pathways are simultaneously at play to result in distinctive histopathological outcomes. The extreme divergence between mouse and rat transcriptomic responses appears to reflect divergent transcriptional-regulatory networks. Taken together, these data suggest that both rat and mouse models should be used to screen the acute hepatotoxic effects of drugs and toxic compounds.
Project description:Metabolic syndrome is a growing concern in developed societies and due to its polygenic nature, the genetic component is only slowly being elucidated. Common mitochondrial DNA sequence variants have been associated with symptoms of metabolic syndrome and may therefore be relevant players in the genetics of metabolic syndrome. We investigate the effect of mitochondrial sequence variation on the metabolic phenotype in conplastic rat strains with identical nuclear but unique mitochondrial genomes, challenged by high-fat diet. We find that the variation in mitochondrial rRNA sequence represents risk factor in the insulin resistance development, which is caused by diacylglycerols accumulation induced by tissue-specific reduction of the oxidative capacity. These metabolic perturbations stem from the 12S rRNA sequence variation affecting mitochondrial ribosome assembly and translation. Our work demonstrates that physiological variation in mitochondrial rRNA might represent a relevant underlying factor in the progression of metabolic syndrome.
Project description:Vertebrate recombination concentrates in meiotic chromatin regions (hotspots) that are opened in some species by the DNA-sequence-specific-binding histone H3 trimethyltransferase PRDM9, while other species recombine in regions with already opened chromatin and other function. Inactivation of the mouse Prdm9 gene induces the shift of hotspots to functional regions, gross fertility reduction in males, and sterility in females. In contrast, the other vertebrate species lacking PRDM9 remain fertile. To resolve this discrepancy, we generated Prdm9 deletions in the Rattus norvegicus genome and generated the first rat genome-wide maps of recombination-initiating double-strand break hotspots. Rat strains carrying the same wild-type Prdm9 allele shared 88% hotspots but strains with different Prdm9 alleles only 3%. After Prdm9 deletion, rat hotspots relocated to functional regions, 40% to positions corresponding to Prdm9-independent mouse hotspots. Despite of hotspot relocation and of decreased fertility, Prdm9-deficient rats of the SHR/OlaIpcv strain produced apparently normal offspring. Rat PRDM9 thus makes recombination landscape unique, but it is unnecessary for recombination. This peculiarity is likely similar for human PRDM9 and may resolve the paradox between the apparently species-specific functions. PRDM9 is known to play a role in speciation, as it causes mouse hybrid sterility via meiotic asynapsis. Besides the expected mild meiotic arrest, we also detected apoptosis of postmeiotic spermatids, suggesting that PRDM9 has an additional role during spermatogenesis and perhaps also in speciation.
Project description:Background: Detecting genetic variation is a critical step in elucidating the molecular mechanisms underlying phenotypic diversity. Until recently, such detection has mostly focused on single nucleotide polymorphisms (SNPs) because of the ease in screening complete genomes. Another type of variant, copy number variation (CNV), is emerging as a significant contributor to phenotypic variation in many species. Here we describe a genome-wide CNV study using array comparative genomic hybridization (aCGH) in a wide variety of chicken breeds. Results: We identified 3,154 CNVs, grouped into 1,556 CNV regions (CNVRs). Thirty percent of the CNVs were detected in at least 2 individuals. The average size of the CNVs detected was 46.3 kb with the largest CNV, located on GGAZ, being 4.3 Mb. Approximately 75% of the CNVs are copy number losses relatively to the Red Jungle Fowl reference genome. The genome coverage of CNVRs in this study is 60 Mb, which represents almost 5.4% of the chicken genome. In particular large gene families such as the keratin gene family and the MHC show extensive CNV. Conclusions: A relative large group of the CNVs are line-specific, several of which were previously shown to be related to the causative mutation for a number of phenotypic variants. The chance that inter-specific CNVs fall into CNVRs detected in chicken is related to the evolutionary distance between the species. Our results provide a valuable resource for the study of genetic and phenotypic variation in this phenotypically diverse species. In total 62 chicken DNA samples (derived from 15 lines) were analyzed against the chicken reference animal UCD001 (the same induvidual that was used to generate the chicken genome reference sequence (ICGSC, 2004)
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human. Rat primary hepatocytes were treated with 30 µM, 100 µM EMD and 0.1% DMSO as vehicle control. All samples were incubated at 24hr and 72hr intervals before RNA extrations and hybridization onto Affymetrix Rat microarrays.
Project description:Background; Mouse and rat models are mainstays in pharmacology, toxicology and drug development â but differences between strains and between species complicate data interpretation and application to human health. Dioxin-like polyhalogenated aromatic hydrocarbons represent a major class of environmentally and economically relevant toxicants. In mammals dioxin exposure leads to a broad spectrum of adverse affects, including hepatotoxicity of varying severity. Several studies have shown that dioxins extensively alter hepatic mRNA levels. Surprisingly, though, analysis of a limited portion of the transcriptome revealed that rat and mouse responses diverge greatly (Boverhof et al. Toxicol Sci 94:398â416, 2006). Results; We employed oligonucleotide arrays to compare the response of 8,125 rat and mouse orthologs. We confirmed that there is limited inter-species overlap in dioxin-responsive genes. Rat-specific and mouse-specific genes are enriched for specific functional groups which differ between species, conceivably accounting for species-specificities in liver histopathology. While no evidence for the involvement of copy-number variation was found, extensive inter-species variation in the transcriptional-regulatory network was identified; Nr2f1 and Fos emerged as candidates to explain species-specific and species-independent responses, respectively. Conclusion; Our results suggest that a small core of genes is responsible for mediating the similar features of dioxin hepatotoxicity in rats and mice but non-overlapping pathways are simultaneously at play to result in distinctive histopathological outcomes. The extreme divergence between mouse and rat transcriptomic responses appears to reflect divergent transcriptional-regulatory networks. Taken together, these data suggest that both rat and mouse models should be used to screen the acute hepatotoxic effects of drugs and toxic compounds. Experiment Overall Design: Wild-type Long-Evans(Kuopio) rats were treated with 100 ug/kg TCDD (n=4) or with cornoil vehicle as control (n=4) for 19 hours. Their livers were then excised, RNA extracted, and the resulting samples hybridized to Affymetrix RAE230A arrays to survey changes in the transcriptome profile.
Project description:Significant qualitative and quantitative differences exist between humans and the animal models used in research. However, significant quantitative and qualitative differences exist between humans and the animal models used in research. This is as a result of genetic variation between human and the laboratory animal. Therefore the development of a system that would allow the assessment of all molecular differences between species after drug exposure would have a significant impact on drug evaluation for toxicity and efficacy. Here we describe a cross-species microarray methodology that identifies and selects orthologous probes after cross-species sequence comparison to develop an orthologous cross-species gene expression analysis tool. The assumptions made by the use of this orthologous gene expression strategy for cross-species extrapolation is that; conserved changes in gene expression equate to conserved pharmacodynamic endpoints. This assumption is supported by the fact that evolution and selection have maintained the structure and function of many biochemical pathways over time, resulting in the conservation of many important processes. We demonstrate this difference using a cross-species methodology by investigating species specific differences of the peroxisome proliferator activator receptor (PPAR) alpha in rat and human.
Project description:Two component sensor-response regulator systems (TCSs) are very common in the genomes of the Streptomyces species that have been fully sequenced to date. It has been suggested that this large number is an evolutionary response to the variable environment that Streptomyces encounter in soil. Notwithstanding this, TCSs are also more common in the sequenced genomes of other Actinomycetales when these are compared to the genomes of most other eubacteria. In this study, we have used DNA/DNA genome microarray analysis to compare fourteen Streptomyces species and one closely related genus to Streptomyces coelicolor in order to identify a core group of such systems. This core group is compared to the syntenous and non-syntenous TCSs present in the genome sequences of other Actinomycetales in order to separate the systems into those present in Actinomycetales in general, the Streptomyces specific systems and the species specific systems. Horizontal transfer does not seem to play a very important role in the evolution of the TCS complement analyzed in this study. However, cognate pairs do not necessarily seem to evolve at the same pace, which may indicate the evolutionary responses to environmental variation may be reflected differently in sequence changes within the two components of the TCSs. The overall analysis allowed subclassification of the orphan TCSs and the TCS cognate pairs and identification of possible targets for further study using gene knockouts, gene overexpression, reporter genes and yeast two hybrid analysis. DNA/DNA comparative analysis using the University of Surrey PCR Microarray chip
Project description:Structural variation has played an important role in the evolutionary restructuring of human and great ape genomes. We generated approximately 10-fold genomic sequence coverage from a western lowland gorilla and integrated these data into a physical and cytogenetic framework to develop a comprehensive view of structural variation. We discovered and validated over 7,665 structural changes within the gorilla lineage including sequence resolution of inversions, deletions, duplications and retrotranspositions. A comparison with human and other ape genomes shows that the gorilla genome has been subjected to the highest rate of segmental duplication. We show that both the gorilla and chimpanzee genomes have experienced independent yet parallel patterns of structural mutation that have not occurred in humans, including the formation of subtelomeric heterochromatic caps, the hyperexpansion of segmental duplications and bursts of retroviral integrations. Our analysis suggests that the chimpanzee and gorilla genomes are structurally more derived than either orangutan or human. all combinations of human, chimpanzee and gorilla are used in 2 different arrayCGH designs. First, a standard 2.1 was used to detected CNVs, and second, we used a custom designed arrayCGH to validate gorilla specific duplications and deletions
Project description:The rat is a widely used model for human physiology and psychology. However, due to their longer gestation periods and husbandry costs relative to mice, as well as the availability of superior molecular techniques to manipulate the mouse genome, relatively few genome-wide studies have been conducted in the rat. As such, a comprehensive analysis of genomic imprinting, which impacts complex traits such as growth and behaviour, has yet to be conducted in the rat. Towards this end, we systematically profiled embryonic and extra-embryonic tissue gene expression and DNA methylation with allele-specific resolution. We identified 14 embryonic and 26 extra-embryonic imprinted genes in the rat. Comparative analyses with mouse revealed that orthologous imprinted gene expression and associated canonical DNA methylation imprints are conserved in the embryo proper of the Muridae family. However, only 3 paternally expressed imprinted genes in the extra-embryonic embryo are conserved in Muridae, all of which are associated with non-canonical H3K27me3 imprints. The discovery of 8 novel candidate non-canonical imprinted genes unique to the rat is consistent with more rapid evolution of extra-embryonic imprinting. Cross-species analysis of novel rat imprinted genes with mouse and human revealed multiple mechanisms by which species-specific imprinted expression may be established, including H3K27me3 deposition in the oocyte, the birth of ZFP57 binding motifs and the insertion of endogenous retroviral promoters. Thus, characterization of the rat imprintome provides insights into the conservation of imprinted gene expression and the etiology of species-specific imprinting.