Project description:Seeds of the desert shrub, jojoba (Simmondsia chinensis) are an abundant, renewable source of liquid wax-esters, which are valued additives in cosmetic products and industrial lubricants. Jojoba is relegated to its own taxonomic family, and there is little genetic information available to elucidate its phylogeny. Here we report the high-quality, 887 Mb, genome of jojoba assembled into 26 chromosomes with 23,490 protein-coding genes. The jojoba genome has only the whole-genome triplication (γ) shared among eudicots, and no recent duplications. These genomic resources coupled with extensive transcriptome, proteome and lipidome data helped to define heterogeneous pathways and machinery for lipid synthesis and storage, provided missing evolutionary history information for this taxonomically-segregated dioecious plant species, and will support efforts to improve the agronomic properties of jojoba
Project description:Comparative studies of gene regulation suggest an important role for natural selection in shaping gene expression patterns within and between species. Most of these studies, however, estimated gene expression levels using microarray probes designed to hybridize to only a small proportion of each gene. Here we used recently-developed RNA sequencing protocols, which side-step this limitation, to assess intra- and inter-species variation in gene regulatory processes in considerably more detail than was previously possible. Specifically, we used RNAseq to study transcript levels in humans, chimpanzees, and rhesus macaques, using liver RNA samples from three males and three females from each species. Our approach allowed us to identify a large number of genes whose expression levels likely evolve under natural selection in primates. These include a subset of genes with conserved sexually dimorphic expression patterns across the three species, which we found to be enriched for genes involved in lipid metabolism. Our data also suggest that while alternative splicing is tightly regulated within and between species, sex-specific and lineage-specific changes in the expression of different splice forms are also frequent. Intriguingly, among genes in which a change in exon usage occurred exclusively in the human lineage, we found an enrichment of genes involved in anatomical structure and morphogenesis, raising the possibility that differences in the regulation of alternative splicing have been an important force in human evolution. Keywords: Gene Regulation Study Examination of gene expression levels in livers from three primate species (human, chimpanzee, and rhesus macaque), using 3 male and 3 female samples from each species.
Project description:The role natural selection plays in governing the locations and early evolution of copy number mutations remains largely unexplored. Here we employ high-density full-genome tiling arrays to create a fine-scale genomic map of copy number polymorphisms (CNPs) in Drosophila melanogaster. We inferred a total of 2,658 independent CNPs, 56% of which overlap genes. These include CNPs likely to be under positive selection, most notably high frequency duplications encompassing toxin-response genes. The locations and frequencies of CNPs are strongly shaped by purifying selection with deletions under stronger purifying selection than duplications. Among duplications, those overlapping exons or introns and those falling on the X-chromosome seem to be subject to the strongest purifying selection. In order to characterize copy number polymorphisms (CNPs) in Drosophila malanogaster, we applied comparative genome hybridization (CGH) using tiling arrays covering the full euchromatic genome of Drosophila melanogaster. We inferred copy number changes with a Hidden Markov Model (HMM) that returned the posterior probabilities for copy number by comparing DNA hybridization intensities between natural isolates and the reference genome strain. Training data for copy number changes were obtained via hybridization with a line known to contain a ~200kb homozygous duplication and from a set of 52 validated homozygous deletions. The probabilities of mutation were parsed to make CNP calls. Key words: comparative genomic hybridization, CGH, copy number polymorphism, CNP, copy number variation, CNV, duplication, deletion
2008-06-06 | GSE11326 | GEO
Project description:Stable species boundaries despite ten million years of hybridization in tropical eels
| PRJNA590038 | ENA
Project description:Genome assembly of Ammopiptanthus nanus, a desert shrub
Project description:Comparative studies of gene regulation suggest an important role for natural selection in shaping gene expression patterns within and between species. Most of these studies, however, estimated gene expression levels using microarray probes designed to hybridize to only a small proportion of each gene. Here we used recently-developed RNA sequencing protocols, which side-step this limitation, to assess intra- and inter-species variation in gene regulatory processes in considerably more detail than was previously possible. Specifically, we used RNAseq to study transcript levels in humans, chimpanzees, and rhesus macaques, using liver RNA samples from three males and three females from each species. Our approach allowed us to identify a large number of genes whose expression levels likely evolve under natural selection in primates. These include a subset of genes with conserved sexually dimorphic expression patterns across the three species, which we found to be enriched for genes involved in lipid metabolism. Our data also suggest that while alternative splicing is tightly regulated within and between species, sex-specific and lineage-specific changes in the expression of different splice forms are also frequent. Intriguingly, among genes in which a change in exon usage occurred exclusively in the human lineage, we found an enrichment of genes involved in anatomical structure and morphogenesis, raising the possibility that differences in the regulation of alternative splicing have been an important force in human evolution. Keywords: Gene Regulation Study
Project description:We are studying the tree P. euphratica growing in its natural habitat in the Negev desert in Israel. We have used leaf RNA samples from trees growing from four different areas in the desert valley Ein Avdat with contrasting growth conditions, with the primary factor being how much water the trees have access to. Area A trees grow close to a stream. Area B trees are further away from the stream. Area C trees are growing on a slope with no water. Parking place trees grow at a parking place (1km from Area A, B and C) where there is a water irrigation system, and these trees are regularly watered once a week. The control sample in each hybridization is always RNA isolated from a pool of 5 trees from the parking place. The hybridizations are comparing the following: Area A -- parking place Area B -- parking place Area C -- parking place Each hybridization is done with a dye swap and three different biological repeats for a total of 18 hybridizations.
2004-11-30 | E-MEXP-182 | biostudies-arrayexpress
Project description:Natural hybridization between invasive Sphagneticola trilobata and native species S. calendulaceae