Project description:Circadian clocks are essential for generating and coordinating rhythms in animals’ physiology, behaviour, and metabolism. These activities are regulated by intracellular molecular clocks that operate with a ~24 hour periodicity. The African striped mouse, Rhabdomys pumilio, is notable for undergoing temporal niche switching from ancestrally nocturnal to diurnal, although the molecular components of its’ circadian organization remain unknown. We undertook transcriptome profiling of daily rhythms in the suprachiasmatic nucleus (SCN) and in the liver, lung and retina of Rhabdomys stably housed under a stable 12h:12h light:dark cycle with bright (n=10) or dim (n=10) daytime light intensity. Tissues were collected at two time points: two hours after lights on (Zeitgeber Time (ZT2)) coinciding with high behavioural activity, or two hours after lights off (ZT14) during the animal’s resting/sleep period, and RNA-sequencing performed.
Project description:In this study, we identified the transcriptome-wide direct RNA target sites of the entire family of Pumilio proteins in the budding yeast Saccharomyces cerevisiae by deep sequencing of RNA regions bound by each of six Pumilio proteins. As a family, the Pumilio proteins of yeast interact with over half of the entire transcriptome. Computational analysis of Pumilio target sites reveal striking differences in mRNA stability, gene set categories, and response to nutrient deprivation conditions based on features of Pumilio binding. Some of these features include variations in primary sequence motif and presence of predicted structured RNA hairpins. Puf6p also binds snoRNAs.
Project description:Purpose: PUMILIO proteins are known to repress target genes by specifically binding to PUMILIO response elements (PREs) in target mRNAs. NORAD is a noncoding RNA that negatively regulates PUMILIO activity. The goal of this study was to determine the gene expression changes that result from knockout of NORAD or overexpression of PUMILIO and to test whether NORAD knockout causes PUMILIO hyperactivity. Methods: RNA-seq libraries were prepared using the TruSeq Stranded Total RNA with Ribo-Zero Human/Mouse/Rat Sample Preparation kit (Illumina) and sequenced using the 100 bp paired-end protocol on an Illumina HiSeq 2000. For comparing NORAD+/+ and NORAD-/- HCT116 cells, 3 biological replicates per genotype were sequenced. For PUM overexpression experiments, 3 replicates of GFP-expressing HCT116 cells (negative control) and 2 independent PUM1- or PUM2-overexpressing clones (2 replicates each) were sequenced. Results: Gene expression profiles show that PUMILIO target genes are downregulated in both NORAD knockout cells and PUMILIO overexpressing cells. Conclusions: These data indicate that NORAD sequesters PUMILIO, preventing excessive repression of PUMILIO target genes that are important for maintaining genomic stability.
Project description:An animal's temporal niche - the time of day at which it is active - is known to drive a variety of adaptations in the visual system. These include variations in the topography, spectral sensitivity and density of retinal photoreceptors, and changes in the eye's gross anatomy and spectral transmission characteristics. We have characterised visual spectral sensitivity in the murid rodent Rhabdomys pumilio (the four-striped grass mouse), which is in the same family as (nocturnal) mice and rats but exhibits a strong diurnal niche. As is common in diurnal species, the R. pumilio lens acts as a long-pass spectral filter, providing limited transmission of light <400 nm. Conversely, we found strong sequence homologies with the R. pumilio SWS and MWS opsins and those of related nocturnal species (mice and rats) whose SWS opsins are maximally sensitive in the near-UV. We continued to assess in vivo spectral sensitivity of cone vision using electroretinography and multi-channel recordings from the visual thalamus. These revealed that responses across the human visible range could be adequately described by those of a single pigment (assumed to be MWS opsin) maximally sensitive at ∼500 nm, but that sensitivity in the near-UV required inclusion of a second pigment whose peak sensitivity lay well into the UV range (λmax<400 nm, probably ∼360 nm). We therefore conclude that, despite the UV-filtering effects of the lens, R. pumilio retains an SWS pigment with a UV-A λmax In effect, this somewhat paradoxical combination of long-pass lens and UV-A λmax results in narrow-band sensitivity for SWS cone pathways in the UV-A range.