Project description:A custom multi-species microarray was used to study gene expression in wild hornyhead turbot (Pleuronichthys verticalis), collected from polluted and clean coastal waters in Southern California and in laboratory male zebrafish (Danio rerio) following exposure to estradiol and 4-nonylphenol. A multi-gene cross species microarray was fabricated as a diagnostic tool to screen the effects of environmental chemicals in fish, for which there is minimal genomic information. The microarray measurement of gene expression in zebrafish, which are phylogenetically distant from turbot, indicates that this multi-species microarray will be useful for measuring endocrine responses in Pleuronectiformes and other fish for which there is minimal genomic sequence information.
Project description:A custom multi-species microarray was used to study gene expression in wild hornyhead turbot (Pleuronichthys verticalis), collected from polluted and clean coastal waters in Southern California and in laboratory male zebrafish (Danio rerio) following exposure to estradiol and 4-nonylphenol. A multi-gene cross species microarray was fabricated as a diagnostic tool to screen the effects of environmental chemicals in fish, for which there is minimal genomic information. The microarray measurement of gene expression in zebrafish, which are phylogenetically distant from turbot, indicates that this multi-species microarray will be useful for measuring endocrine responses in Pleuronectiformes and other fish for which there is minimal genomic sequence information.
Project description:Microarrays are useful tools for detecting and quantifying specific functional and phylogenetic genes in natural microbial communities. In order to track uncultivated microbial genotypes and their close relatives in an environmental context, we designed and implemented a “genome proxy” microarray that targets microbial genome fragments recovered directly from the environment. Fragments consisted of sequenced clones from large-insert genomic libraries from microbial communities in Monterey Bay, the Hawaii Ocean Time-series station ALOHA, and Antarctic coastal waters. In a prototype array, we designed probe sets to thirteen of the sequenced genome fragments and to genomic regions of the cultivated cyanobacterium Prochlorococcus MED4. Each probe set consisted of multiple 70-mers, each targeting an individual ORF, and distributed along each ~40-160kbp contiguous genomic region. The targeted organisms or clones, and close relatives, were hybridized to the array both as pure DNA mixtures and as additions of cells to a background of coastal seawater. This prototype array correctly identified the presence or absence of the target organisms and their relatives in laboratory mixes, with negligible cross-hybridization to organisms having ≤~75% genomic identity. In addition, the array correctly identified target cells added to a background of environmental DNA, with a limit of detection of ~0.1% of the community, corresponding to ~10^3 cells/ml in these samples. Signal correlated to cell concentration with an R2 of 1.0 across six orders of magnitude. In addition the array could track a related strain (at 86% genomic identity to that targeted) with a linearity of R2=0.9999 and a limit of detection of ~1% of the community. Closely related genotypes were distinguishable by differing hybridization patterns across each probe set. This array’s multiple-probe, “genome-proxy” approach and consequent ability to track both target genotypes and their close relatives is important for the array’s environmental application given the recent discoveries of considerable intra-population diversity within marine microbial communities. Keywords: target addition experiment, proof-of-concept for GPL6012