Molecular Basis of Maintaining Circannual Rhythm in the Skin of Cashmere Goat

BackgroundThe cashmere goat (Capra hircus) is famous for the fine quality cashmere wool. The cashmere is produced by secondary hair follicle that shows seasonal rhythm in growth. Thus, in this study, the skin of cashmere goat was selected as a model to illustrate the circannual rhythm of skin. ResultsThe skin whole length transcriptome obtained by PacBio single-molecule long-read sequencing (SMRT) technology were mixed from four selected months. The transcriptome yielded 82,382 high quality non-redundant transcripts belonging to 193,310 genes, including 4,237 novel genes. Other 39 skin transcriptomes sequenced by Illumina Hi-Seq2500 were sampled from Dec. 2014 to Dec. 2015, from which we found 980 genes were differentially expressed. Of these genes, 403 seasonal rhythm genes (SRGs) were expressed and exhibited a seasonal pattern in skin. Some SRG genes related to the hormone secretion and eyes morphogenesis were enriched in skin. These SRG genes gradually increased their expression level under short light, reached the peak near the summer solstice, and then began to decline. We found that the expression of Dio1 gene may be affected by the photoperiod that induces transformation from the inactive T4 to active thyroid hormone T3 in the skin and led to the difference between the skin circannual rhythm and the core circannual rhythm. The results also showed that miRNAs were differentially expressed as the daylight length changed throughout a year. Furthermore, the skin expressed eye morphogenesis-related genes and miRNAs, which suggested some cells in the skin could have the potential of light sensitivity. ConclusionTaking together, these results revealed that SRGs could regulate the downstream gene expression and physiological process in the skin to adapt to the season change. We provided a hypothesis to describe how goat skin makes the own rhythm and gets the clue from the environment factor.

Molecular Basis of Maintaining Circannual Rhythm in the Skin of Cashmere Goat

The cashmere goat (Capra hircus) is famous for the fine quality cashmere wool. The cashmere is produced by secondary hair follicle that the growth shows seasonal rhythm. Thus, in this study, the skin of cashmere goat was selected as a model to illustrate the circannual rhythm of skin. The whole length skin transcriptome mixed from selected four months was obtained by PacBio single-molecule long-read sequencing (SMRT) technology. We generated 82,382 high quality non-redundant transcripts belonging to 193,310 genes, including 4,237 novel genes. Other 39 skin transcriptomes sampled from Dec. 2014 to Dec. 2015 were sequenced by Illumina Hi-Seq2500, we found 980 genes were differentially expressed. Of these genes, 403 seasonal rhythm genes (SRGs) were expressed and exhibited a seasonal pattern in skin. The results also showed that miRNAs were differentially expressed as the daylight length changed throughout a year. Some SRG genes related to the hormone secretion and eyes morphogenesis were enriched in skin. These genes gradually increased their expression level under short light, reached the peak near the summer solstice, and then began to decline. We found that the expression of Dio1 gene may be affected by the photoperiod that induces transformation from the inactive T4 to active thyroid hormone T3 in the skin and led to the difference between the skin circannual rhythm and the core circannual rhythm. Furthermore, the skin expressed eye morphogenesis-related genes and miRNAs, which suggested some cells in the skin could have the potential of light sensitivity. These results revealed that SRGs could regulate the downstream gene expression and physiological process in the skin to adapt to the season change.

Circadian versus circannual rhythm in the photoperiodic programming of seasonal responses in Eurasian tree sparrow (Passer montanus)

Experiments were done on the subtropical tree sparrow to examine whether day length, as a proximate factor, involves circadian rhythm in timing seasonal responses or these events are programmed by the mediation of endogenous circannual rhythm.

Genomic basis of circannual rhythm in the european corn borer moth

ABSTRACTGenetic variation in life-history timing allows populations to synchronize with seasonal cycles but little is known about the molecular mechanisms that produce differences in circannual rhythm in nature. Changes in diapause timing in the European corn borer moth (Ostrinia nubilalis) have facilitated rapid response to shifts in winter length encountered during range expansion and from climate change, with some populations emerging from diapause earlier to produce an additional generation per year. We identify genomic variation associated with changes in the time spent in winter diapause and show evidence that the circadian clock genes period (per) and pigment dispersing factor receptor (Pdfr) interact to underlie this adaptive polymorphism in circannual rhythm. Per and Pdfr are located within two epistatic QTL, strongly differ in allele frequency among individuals that pupate earlier or later, have the highest linkage disequilibrium among gene pairs in the QTL regions despite separation by > 4 megabases, and possess amino-acid changes likely to affect function. One per mutation in linkage disequilibrium with Pdfr creates a novel putative clock-cycle binding site found exclusively in populations that pupate later. We find associated changes in free-running daily circadian rhythm, with longer daily rhythms in individuals that end diapause early. These results support a modular connection between circadian and circannual timers and provide testable hypotheses about the physiological role of the circadian clock in seasonal synchrony. Winter length is expected to continually shorten from climate warming and we predict these gene candidates will be targets of selection for future adaptation and population persistence.