Project description:While the vertebrate body plan is highly conserved amongst all species of this taxon, extreme variations thereof can be documented in snakes, which display both an absence of limbs and an unusually elongated trunk. As Hox genes are strong candidates both for the making and the evolution of this body plan, their comparative study in such a morphologically diverged group is informative regarding their potential causative importance in these processes. In this work we use an interspecies comparative approach where different aspects of regulation at the HoxD locus are investigated. We find that although spatial collinearity and associated epigenetic mark dynamics are conserved in the corn snake, other regulatory modalities have been largely restructured. A BAC transgenic approach indeed revealed that, while the majority of mesodermal enhancers in vertebrates appear to be mostly located outside of the cluster, the corn snake contains most mesodermal trunk enhancers within the HoxD cluster. We also find that, despite the absence of limbs and an altered Hoxd gene regulation in external genitalia, the bimodal chromatin structure at the corn snake HoxD locus is maintained. The analysis of particular enhancer sequences initially defined in the mouse and further isolated at the snake orthologous locus showed differences in their specificities for the limb and genital bud expression. Of particular interest, a snake counterpart of a mouse limb-only enhancer sequence evolved into a genital-only enhancer. Such a regulatory exaptation suggests that enhancer versatility may have been an important factor to accompany the transition towards the snake body plan. These results show that vertebrate morphological evolution is likely to have been associated with extensive reorganization at the HoxD regulatory landscapes while respecting a very conserved general regulatory framework.
Project description:Comparative-genomic studies have reported widespread variation in levels of gene expression within and between species. In the vast majority of cases, the phenotypic and evolutionary relevance of regulatory change is unknown. We haveu sed a wild Malaysian population of S. cerevisiae as a testbed in the search to identify organismal correlates of regulatory variation. Malaysian yeast, when cultured in standard medium, activated regulatory programs that protect cells from the toxic effects of high iron. Analysis of differential gene expression between three Malaysian and two Wine/European isolates and allele-specific expression within three Malaysian x Wine/European hybrids.
Project description:The Malaysian Node of the Human Variome Project Database (MyHVPDb) is a country specific database of human variant and gene mutation that was established in 2011. This ethnic specific mutation and variation databases are being continuously updated, recording extensive information over the genetic heterogeneity of the Malaysian ethnic groups. The database comprises of SNP Database and Mutation Database. The SNP database has stored 291718 SNPs that was obtained by genotyping the SNPs of 101 healthy individuals from six Malay sub-ethnic groups which consist of Malay Kelantan, Malay Banjar, Malay Kedah, Malay Jawa, Malay Bugis and Malay Champa.
Project description:We used gene expression accompanied by physical characteristics and gill Na+/K+-ATPase activity to analyze physiological differences associated with two life history variations of juvenile fall Chinook Salmon in the Snake River basin. Subyearlings originating in the Snake River typically migrate seaward as subyearlings, whereas many subyearlings from the Clearwater River delay seaward migration during summer and complete seaward migration the following spring as yearlings. We examined gill Na+/K+-ATPase activity and gene expression of subyearlings at different times during rearing and seaward emigration. Natural-origin Snake River subyearlings rearing under an increasing photoperiod and seasonally increasing temperatures showed a typical increasing pattern of parr to smolt gill Na+/K+-ATPase activity development, which then declined into autumn. In contrast, Clearwater River subyearlings that had experienced cooler temperatures showed no pattern of increasing gill Na+/K+-ATPase activities and were not different from parr. Liver transcription of genes involved in DNA repair and binding, the cell cycle, metabolism (steroid, fatty acid and other metabolic pathways) iron homeostasis, heme and oxygen binding, the immune response, and male sexual development were enriched amongst genes differentially expressed between Snake River parr versus smolts. Gene expression results confirmed that Clearwater River subyearlings were parr-like in their physiological status. By autumn, subyearlings had low gill Na+/K+-ATPase activities despite their large size and external smolt characteristics. We suggest that environmental factors like temperature and photoperiod influence subyearling physiological status in each river that ultimately dictates juvenile life history pathways. Non-migrating and migrating natural subyearling fall Chinook salmon were collected from the Snake River. Non-migrating natural subyearling fall Chinook salmon were collected from the Clearwater River. Twelve fish were collected at each of four different time points for a total of 48 fish. Total RNA was extracted from the liver of each fish. Equal amounts of RNA from three fish were pooled to create four pools of RNA per time point. Each RNA pool was hybridized to an array for a total of 16 arrays with four arrays per time point.