Project description:Purpose: Photoperiod is known to cause physiological changes in seasonal mammals, including body weight, physical activity, and reproductive status. Because cats are seasonal breeders, we recently tested the effects of day length on resting metabolic rate, voluntary physical activity, and food intake. In that study, resting metabolic rate, physical activity, and food intake to maintain body weight were greater in cats exposed to long days vs. short days. Because photoperiod has also been demonstrated to affect adipose tissue gene expression in several species, including dairy cows, sheep, and Siberian hamsters, the objective of this study was to determine the effects of day length on the adipose transcriptome profile of cats as assessed by RNA-seq. Methods: Ten healthy adult neutered male domestic shorthair cats were used in a randomized crossover design study. During two 12-wk periods, cats were exposed to either short days (8 hr light:16 hr dark) or long days (16 hr light:8 hr dark). Cats were fed a commercial diet to maintain baseline body weight. Subcutaneous adipose biopsies were collected at wk 12 of each period for RNA isolation and Illumina sequencing. Results: A total of 578 million sequences (28.9 million/sample) were generated by Illumina sequencing. Using a raw p value of P<0.005, 170 mRNA transcripts were differentially expressed between short day- and long day-housed cats. Of the 170 transcripts highlighted, 25 annotated transcripts were up-regulated, while 116 annotated transcripts were down-regulated by long days. Another 29 un-annotated transcripts (name and function not known) were also different between groups. In general, adipose tissue of long day-housed cats had greater expression of genes involved with cholesterol trafficking, fatty acid synthesis and immune function, and lower expression of genes involved with cell cycle and growth, cell development and structure, and protein processing, when compared to short day-housed cats. Subcutaneous adipose tissue mRNA profiles of healthy adult neutered male cats exposed to short days (8 hr light: 16 hr dark) or long days (16 hr light: 8 hr dark) using Illumina sequencing.

Project description:The circadian profile of the transcriptomes in murine tissues was compared between groups of young and old male mice. The oscillatory phase and absolute expression levels were evaluated as a function of biological age. Distinct differences in multiple pathways were apparent based on biological and circadian time in a tissue specific manner. A total of 18 young (5 month) and old (24 month) C57BL/6 mice were acclimated to a set 12 hr light dark cycle and fed ad lib on standard lab chow for 2 weeks in the PBRC Comparative Biology Core Facility. Five days prior to the study, the mice were converted to constant darkness (red light) regimen. On the day of the study, mice were euthanized by CO2 asphyxiation after ad lib feeding overnight in groups of 3 animals per young or old cohort at 4 hr intervals beginning at 7 AM and ending at 3 AM on a single day (July, 2009). The body weight of each animal was recorded prior to dissection of the following tissues: brown adipose tissue (BAT), inguinal white adipose tissue (iWAT), and liver. Individual tissues were weighed prior to freezing in liquid nitrogen. Samples were stored at -80oC until use.Total RNA was isolated from the BAT, eWAT, and liver tissues using TriReagent (MRC, Cincinnati OH) in accordance with the manufacturer’s recommendations. The Illumina TotalPrep RNA Amplification Kit (Applied Biosystems Inc., Foster City, CA, Catalog #AMIL1791) was used to create labeled cRNA from 750ng of input total RNA according to the manufacturer’s protocol. The labeled cRNA samples were then assessed for quality and quantity using a NanoDrop and an Agilent Bioanalyzer. The MouseWG-6 v2 Beadchip (Illumina Sentrix Beadchip Array #11278593) contains 45,200 transcripts and allows 6 samples to be interrogated in parallel. 1.5ug of each labeled cRNA was hybridized to each array according to the manufacturer's protocol. Experimental group samples were distributed randomly across all beadchips. After an 18 hour hybridization at 58°C, the beadchips were processed according to manufacturer’s protocol and scanned using an Illumina BeadArray Reader (Illumina, Inc., San Diego, CA).

Dataset Information

Circadian clock in cartilage

Publications

The circadian clock in murine chondrocytes regulates genes controlling key aspects of cartilage homeostasis.

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