Project description:RNA-seq technology was used to identify differentially localized transcripts from Xenopus laevis and Xenopus tropicalis stage VI oocytes. Besides the discovery of a group of novel animally enriched RNAs, this study revealed a surprisingly low conservation of vegetal RNA localization between the two frog species. mRNA profiles of Xenopus laevis and Xenopus tropicalis animal and vegetal oocyte halves were generated by RNA-seq technology. For Xenopus laevis, animal and vegetal oocyte RNA preparations from two different females were generated in duplicates. For Xenopus tropicalis, animal and vegetal oocyte RNA preparations from two different females were analyzed.
Project description:RNA-seq technology was used to identify differentially localized transcripts from Xenopus laevis and Xenopus tropicalis stage VI oocytes. Besides the discovery of a group of novel animally enriched RNAs, this study revealed a surprisingly low conservation of vegetal RNA localization between the two frog species.
Project description:Hybridization of eggs and sperm from closely related species can give rise to genetic diversity, or can lead to embryo inviability due to incompatibility. Although central to evolution, the cellular and molecular mechanisms underlying postzygotic barriers that drive reproductive isolation and speciation remain largely unknown. Species of the African Clawed frog Xenopus provide an ideal system to study hybridization and genome evolution. Xenopus laevis is an allotetraploid with 36 chromosomes that arose through interspecific hybridization of diploid progenitors, whereas Xenopus tropicalis is a diploid with 20 chromosomes that diverged from a common ancestor ~48 million years ago. Differences in genome size between the two species are accompanied by organism size differences, and size scaling of the egg and subcellular structures such as nuclei and spindles formed in egg extracts. Nevertheless, early development transcriptional programs, gene expression patterns, and protein sequences are generally conserved. Interestingly, whereas the hybrid produced when X. laevis eggs are fertilized by X. tropicalis sperm (le×ts) is viable, the reverse hybrid (te×ls) dies prior to gastrulation. Here, we applied cell biological tools and high-throughput methods to study the mechanisms underlying hybrid inviability. We reveal that two specific X. laevis chromosomes are incompatible with the X. tropicalis cytoplasm and are mis-segregated during mitosis, leading to unbalanced gene expression at the maternal to zygotic transition, followed by cell-autonomous catastrophic embryo death.
Project description:Comprehensive RNA-seq experiments to measure the expression of homoeologs across different tissues, as a part of the Xenopus laevis genome project. This work is funded by Agency Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT; "Genome Science" Grant ID 221S0002). Collect mRNA from whole tissue; two female frogs were used as donors for most tissues (Taira dataset for one frog, Ueno dataset for the other frog); testis samples were collected from two male frogs (sibling of two female donors)
Project description:Epimorphic regeneration is the process by which complete regeneration of a complex structure such as a limb occurs through production of a proliferating blastema. This type of regeneration is rare among vertebrates but does occur in the African clawed frog Xenopus laevis, traditionally a model organism for the study of early development. Xenopus tadpoles can regenerate tails, limb buds and the lens of the eye, although the ability of the latter two organs to regenerate diminishes with advancing developmental stage. Using a heat shock inducible transgene that remains silent unless activated, we have established a stable line of transgenic Xenopus in which the BMP inhibitor Noggin can be over-expressed at any time during development. We have previously shown that activation of this transgene blocks regeneration of the tail and limb of Xenopus tadpoles. In the current study, we have taken advantage of this transgenic line to directly compare gene expression in same stage regenerating vs. non-regenerating hind limb buds. Using Affymetrix gene chip analysis, we have identified genes whose expression levels are linked to regenerative success. These include the BMP inhibitor Gremlin and the stress protein Hsp60 (no blastema in zebrafish). Analysis of overrepresented Gene Ontology functional groupings suggests that successful regeneration in the Xenopus hind limb depends on induction of stress response pathways. Furthermore, as expected, genes involved in embryonic development and growth are also significantly over-represented in regenerating early hind limb buds. Keywords: Differential expression, regeneration
Project description:In this work, we developed a microprobe capillary electrophoresis high-resolution mass spectrometry approach to identify proteins in single identified cells in live embryos of the South African clawed frog (Xenopus laevis) and also zebrafish. We used a pulled borosilicate capillary to aspirate a calibrated portion of the cell of interest. Proteins in the collected aspirate were detected and quantified via a bottom-up proteomic workflow that was downscaled to the single cells. The microprobe mass spectrometry platform is scalable to smaller cells in live, morphologically complex, developing embryos. As an example, we used this approach to analyze proteomic changes in cells that form a clone in the early developing Xenopus laevis embryo.