Project description:Several microorganisms have wide temperature growth range and versatility to tolerate large thermal fluctuations in diverse environments. To better understand thermal adaptation of psychrotrophs, Exiguobacterium sibiricum strain 255-15 was used, a psychrotrophic bacterium that grows from -5°C to 39°C. Its genome is approximately 3 Mb in size, has a GC content of 47.7% and includes 2,978 putative protein-encoding genes (CDS). The genome and transcriptome analysis along with the organism's known physiology was used to better understand its thermal adaptation. A total of about 27%, 3.2% and 5.2% of E. sibiricum strain 255-15 CDS spotted on the DNA microarray yielded differentially expressed genes in cells grown at -2.5°C, 10°C and 39°C, respectively, when compared to cells grown at 28°C. The hypothetical and unknown genes represented 10.6%, 0.89% and 2.3% of the CDS differentially expressed when grown at -2.5°C, 10°C and 39°C versus 28°C. The transcriptome analyses showed that E. sibiricum is constitutively adapted to cold temperatures since little differential gene expression was observed at growth temperatures of 10°C and 28°C, but at the extremities of its Arrhenius growth profile, namely -2.5°C and 39°C, much more differential gene expression occurred. The genes that responded were more typically associated with stress response. Keywords: stress response to cold and hot temperatures
Project description:Post-transcriptional mechanisms play an important role in the control of gene expression. RNA-binding proteins are key players in the post-transcriptional control of many neural genes and they participate in multiple processes, from RNA splicing and mRNA transport to mRNA stability and translation. Our laboratory has developed the first mouse model overexpressing a RNA-binding protein, the ELAV-like protein HuD, in the CNS under the control of the CaMKinII alpha promoter. Initial behavioral characterization of the mice revealed that they had significant learning deficits together with abnormalities in prepulse inhibition (PPI). At the molecular level, we found that the expression of the growth-associated protein GAP-43, one of the targets of HuD, was increased in the hippocampus of HuD transgenic mice. Besides binding and stabilizing the GAP-43 mRNA, HuD was shown to bind in vitro or in vivo the mRNAs of acetylcholinesterase, tau, p21, neuroserpin, and MARCKS among others. To identify additional targets of HuD, we propose to pull down the RNAs bound to myc-tagged HuD in vivo in the brains of HuD transgenic mice, to isolate these bound RNAs and use these to probe DNA microarrays. We will use pull downs using non-immune IgGs as controls. To test our hypothesis we propose 2 specific aims:; 1) To identify the targets of HuD in HuD overexpressor mice and; 2) To compare these target mRNAs to those we identified previously as having increased levels of expression in the hippocampus of HuD transgenic mice (see protocol # Perrone-Bizzozero-5R01NS030255-12) and/or those that show increased expression in dentate granule cells of HuD transgenic mice ( protocol # perro-affy-mouse-309741); Based upon the role of the RNA-binding HuD in neuronal development and synaptic plasticity, we expect that HuD targets will include mRNAs for proteins involved in these processes. All mice are in C57BL/6 background and are male approximately 60 days old. To identify target of HuD in our transgenic mice, we will homogenize the homogenize the hippocampi (2 per animal) of 3 transgenic mice and use these protein extracts for immunoprecipitation assays. Briefly, transgenic myc-tagged HuD protein will be immunoprecipitated using myc-tag antibodies and protein-G agarose beads and samples will be sent to T-Gen for RNA isolation, single round amplification and probing of DNA microarrays. We will use non-immune IgG as a negative control. Conditions:; Pooled Extracts from 3 transgenic mice IP with myc-tag antibodies: Triplicates; Pooled extract from 3 transgenic mice IP with non-immune IgGs (negative control): duplicates