Mapping gene expression in two Xenopus: evolutionary constraints and developmental flexibility
Ontology highlight
ABSTRACT: Variation in gene expression is known to be important for morphological evolution, however little is known about its general propensity. Here we examine a pair of frogs – Xenopus laevis and Xenopus tropicalis – with highly similar embryology, and ask how their transcriptomes compare. Despite separation for over ~30-90 million years we found a strong conservation in gene expression in the vast majority of the expressed orthologs. There were a significant number of changes in the level of expression of genes. Changes in timing of expression, heterochrony, were much less common, and were often found in genes and pathways that reflect responses to selective features of the environment. Differences in gene expression levels were concentrated in the earliest embryonic stages. We propose that different evolutionary rates across developmental stages may be explained by the stabilization of cell fate determination pathways in later stages.
Project description:Variation in gene expression is known to be important for morphological evolution, however little is known about its general propensity. Here we examine a pair of frogs M-bM-^@M-^S Xenopus laevis and Xenopus tropicalis M-bM-^@M-^S with highly similar embryology, and ask how their transcriptomes compare. Despite separation for over ~30-90 million years we found a strong conservation in gene expression in the vast majority of the expressed orthologs. There were a significant number of changes in the level of expression of genes. Changes in timing of expression, heterochrony, were much less common, and were often found in genes and pathways that reflect responses to selective features of the environment. Differences in gene expression levels were concentrated in the earliest embryonic stages. We propose that different evolutionary rates across developmental stages may be explained by the stabilization of cell fate determination pathways in later stages. 96 microarrays, across developmental stages in Xenopus laevis and Xenopus tropicalis in wildtype embryos. For each of the two timecourse indepenent triplicates (clutches) were generated.
Project description:Cancer is often caused by mutations in many genes. Although genomic studies have identified many oncogenes and tumor suppressor genes, gene sets involved in tumorigenesis remain poorly understood. Xenopus, a genus of aquatic frogs, is a useful model to identify gene sets because it can be genetically and experimentally analyzed. So we analyzed gene expression in tumor tissues of three individuals in Xenopus tropicalis and compared with that in normal tissues.
Project description:In this experiment, we show transcription profiling of the Xenopus tropicalis tadpole tail tissue regeneration following removal. The tail tissues include its spinal cord, notochord, muscle, and dorsal aorta. We characterized the early, intermediate, and late stages of Xenopus tropicalis tail regeneration using the Xenopus tropicalis Affymetrix genome array in biological replicate.
Project description:Here we present clear patterns of age-associated changes in DNA methylation in the aquatic vertebrate species Xenopus tropicalis. We selected approximately 3500 sites highly correlated with age from WGBS data from 9 frogs of 3 different age groups (young, approx. 1 year old; mature, approx. 5 years old; old, approx. 9 years old - GSE221656) and designed probes for the development of cost effective targeted bisulfite sequencing (TBSeq) assay. Here, we present the TBSeq assay in sixteen different frogs as a pilot experiment to validate our previous findings.
Project description:Changes in gene expression in the preoptic area/hypothalamus/thalamus of Xenopus tropicalis tadpoles were analyzed using RNAseq at four stages of metamorphosis.
Project description:Frogs are an ecologically diverse and phylogenetically ancient group of anuran amphibians that include important vertebrate cell and developmental model systems, notably the genus Xenopus. Here we report a high-quality reference genome sequence for the western clawed frog, Xenopus tropicalis, along with draft chromosome-scale sequences of three distantly related emerging model frog species, Eleutherodactylus coqui, Engystomops pustulosus and Hymenochirus boettgeri. Frog chromosomes have remained remarkably stable since the Mesozoic Era, with limited Robertsonian (i.e., centric) translocations and end-to-end fusions found among the smaller chromosomes. Conservation of synteny includes conservation of centromere locations, marked by centromeric tandem repeats associated with Cenp-a binding, surrounded by pericentromeric LINE/L1 elements. We explored chromosome structure across frogs, using a dense meiotic linkage map for X. tropicalis and chromatin conformation capture (Hi-C) data for all species. Abundant satellite repeats occupy the unusually long (~20 megabase) terminal regions of each chromosome that coincide with high rates of recombination. Both embryonic and differentiated cells show reproducible association of centromeric chromatin, and of telomeres, reflecting a Rabl-like configuration. Our comparative analyses reveal 13 conserved ancestral anuran chromosomes from which contemporary frog genomes were constructed.
Project description:Determine the adenylation state of maternal mRNAs during oocyte maturation and early cleavage stages of the xenopus tropicalis embryos
Project description:The aim of the study was to determine the protein composition of cornified claws of the western clawed frog (Xenopus tropicalis) in comparison to clawless toe tips and back skin. Cornified claws develop on toes I, II, III of the hind limbs, which we refer to as hind limb inner (HI) toes. Toes IV, V of the hind limbs, here referred to as hind limb outer (HO) toes lack claws. Proteins were prepared from HI toe tips including claws, HO toe tips and back skin (BSK) of frogs each (F1, F2, F3) and subjected to proteomic analysis.
Project description:Changes in DNA methylation in the preoptic area/hypothalamus/thalamus of Xenopus tropicalis tadpoles were analyzed using Methylated DNA Capture sequencing (MethlCap-seq) at four stages of metamorphosis.
Project description:LCM-RNA-Seq data obtained from Xenopus tropicalis chondrocytes and osteoblasts at different stages of differentiation -immature chondrocytes and mature (hypertrophic) chondrocytes- isolated from the ceratohyal. Osteoblasts isolated from the mandible (dentary bone).