Project description:Time series microarray analysis on the photosynthetic ciliate was conducted using an oligochip containing 15,654 genes designed from Teleaulax amphioxeia ESTs
Project description:Dicer-dependent small non-coding RNAs play important roles in gene regulation in a wide variety of organisms. Endogenous small interfering RNAs (siRNAs) are part of an ancient pathway of transposon control in plants and animals. The ciliate, Oxytricha trifallax, has approximately 16,000 gene-sized chromosomes in its somatic nucleus. Long non-coding RNAs establish high ploidy levels at the onset of sexual development, but the factors that regulate chromosome copy numbers during cell division and growth have been a mystery. We report a novel function of a class of Dicer (Dcl-1)– and RNA-dependent RNA polymerase (RdRP)– dependent endogenous small RNAs in regulating chromosome copy number and gene dosage in O. trifallax. Asexually growing populations express an abundant class of 21nt sRNAs that map to both coding and non-coding regions of most chromosomes. These sRNAs are bound to chromatin and their levels surprisingly do not correlate with mRNA levels. Instead, the levels of these small RNAs correlate with genomic DNA copy number. Reduced sRNA levels in dcl-1 or rdrp mutants lead to concomitant reduction in chromosome copy number. Furthermore, these cells show no signs of transposon activation, but instead display irregular nuclear architecture and signs of replication stress. In conclusion, Oxytricha Dcl-1 and RdRP-dependent small RNAs that derive from the somatic nucleus contribute to the maintenance of gene dosage, possibly via a role in DNA replication, offering a novel role for these small RNAs in eukaryotes.
Project description:Analysis of epithelial explants injected with the intracellular domain of Notch (ICD) to block the formation of multi-ciliate cells, either alone or along with FoxJ1. FoxJ1 misexpression leads to the induction fo ectopic cilia in Xenopus laevis epithelia. Results show which genes are affected by FoxJ1 during the induction of ectopic cilia. Ciliated cells that produce a leftward fluid flow have been proposed to mediate left-right patterning in many vertebrate embryos. These cilia combine features of primary sensory and motile cilia, but how such cilia are specified is unknown. We address this issue by analyzing the Xenopus and Zebrafish homologs of FoxJ1, a forkhead transcription factor necessary for ciliogenesis in multi-ciliate cells of the mouse. We show that the cilia that underlie left-right patterning on the Xenopus gastrocoel roof plate (GRP) and Zebrafish Kupfferâs vesicle (KV) are severely shortened or fail to form in FoxJ1 morphants. We also show that misexpressing XFoxJ1 is sufficient to induce ectopic GRP-like cilia formation in frog embryos. Microarray analysis indicates that XFoxJ1 induces the formation of cilia by upregulating the expression of motile cilia genes. These results indicate that FoxJ1 is a critical determinant in specifying cilia used in left-right patterning. Experiment Overall Design: 2-cell stage Xenopus embryos were injected with synthetic mRNA encoding ICD alone or along with FoxJ1. At stage 9/10 the presumptive ectoderm was cut off the embryo and cultured on a fibronectin coated coverslip. At stage 22 RNA was harvested from explants and used as the starting material for arrays.
Project description:The goal of this study was to use heterologous microarray hybridization to determine genomic content shared among different vesicomyid symbionts. These symbionts are closely related and can be thought of as different strains of bacteria, facilitating the use of heterologous microarray hybridization to determine genomic content. Keywords: comparative genomic hybridization Microarrays were built off the Ruthia magnifica genome and two replicate hybridizations to this organism were used as a baseline for comparisons. Genomic DNA from two other vesicomyid symbionts (Calyptogena kilmeri and C. pacifica symbionts) was also hybridized to the array with three biological replicates for each sample.