Project description:A genome-wide association study was performed on ovaries from Siberian hamsters raised in either long or short photoperiod. Few differences between long and short photoperiod were noted at 3 wk of age, when ovarian histology was identical, whereas many differences in gene expression were noted at 8 wk of age, when ovarian histologies were markedly different. Hamsters were gestated and maintained in 16 or 10 hours of light per day, the latter short photoperiod delays sexual maturity and alters ovarian histology. Differences in gene expression were evaluated by microarray at 3 and 8 wk of age, as were changes between 3 and 8 wk of age in each photoperiod.
Project description:Young Drosophila females respond to low temperature and short photoperiod by developmental arrest of the ovaries. This form of reproductive diapause is a winter adaptation. Here we used Affymetrix microarrays to study global expression in female heads associated with diapause.
Project description:Living organisms detect seasonal changes in day length (photoperiod), and alter their physiological functions accordingly, to fit seasonal environmental changes. This photoperiodic system is implicated in seasonal affective disorders and the season-associated symptoms observed in bipolar disease and schizophrenia. Thyroid-stimulating hormone beta subunit (Tshb), induced in the pars tuberalis (PT), plays a key role in the pathway that regulates animal photoperiodism. However, the upstream inducers of Tshb expression remain unknown. Here we show that late-night light stimulation acutely triggers the Eya3-Six1 pathway, which directly induces Tshb expression. Using melatonin-proficient CBA/N mice, which preserve the photoperiodic Tshb-expression response, we performed a genome-wide expression analysis of the PT under chronic short-day and long-day conditions. These data comprehensively identified long-day and short-day genes, and indicated that late-night light stimulation induces long-day genes. We verified this by advancing and extending the light period by 8 hours, which acutely induced Tshb expression, within one day. In a genome-wide expression analysis under this condition, we searched for candidate upstream genes by looking for expression that preceded Tshb’s, and identified Eya3 gene. These results elucidate the comprehensive transcriptional photoperiodic response in the PT, revealing the complex regulation of Tshb expression and unexpectedly rapid response to light changes in the mammalian photoperiodic system. Mice were separated into 2 groups. One group was maintained under the short-day conditions (light: dark = 8 h:16 h, ZT0 = lights on, ZT8 = lights off, 400 lux) and the other was housed under long-day conditions (light:dark = 16 h:8 h, ZT0 = lights on, ZT16 = lights off, 400 lux) for 2 weeks. The PTs of both groups were retrieved every 4 h for 1 day (6 time points for each group), starting at ZT0. For the experiments performed during the first day of the long-day conditions, we applied two different conditions, following 3 weeks under short-day conditions. In one, the light-onset was advanced by 8 hours (advance condition), and in the other, the dark period was delayed by 8 hours (delay condition). PTs from both groups were obtained every 4 h for 1 day, starting at the lights-on time. (Lights on for the advance condition was ZT16 as defined by the short-day condition. Lights on for the delay condition was ZT0). We sampled 25 mice at each time point. This whole procedure was repeated twice (n = 2) to obtain experimental replicates.
Project description:Rats were housed in either long day (LD, 16:8 hours, light:dark) or short day (SD, 8:16 hours, light dark) photoperiods for 3, 14 and 28 days and brains removed, frozen on dry ice and then hypothalamic arcuate nucleus tissue blocks cut for RNA extraction. At each time point 4 rats were used in each photoperiod giving 24 rats in total.
Project description:Various physiological processes and behaviours are controlled by changing daylength. To dissect genes involved in the photoperiodic changes in physiology and behaviour, global expression analysis was performed using quail kept under short and long day conditions. Experiment Overall Design: The mediobasal hypothalamus (MBH) of quail kept under short day condition (6h light:18h dark) or long day condition (20h light:4h dark) were collected for RNA extraction. Pooled total RNA from three MBHs was labelled and hybridized on Affymetrix microarrays. Samples were collected from 6 birds every 4h during a 24 h cycle and were analyzed in duplicate set of array (two biological replicates).
Project description:Plants adapt to the prevailing photoperiod by optimally adjusting growth and flowering to the availability of energy. When Arabidopsis thaliana plants are grown in long days individual leaf growth is favoured, whereas whole plant leaf area is decreased because of the rapid shift to floral stages and, consequently, the low number of total leaves. To understand the molecular profiles of adaptation to long-day conditions we profiled Arabidopsis leaf number six of plants grown in 16 hours of light at four developmental stages both at the end of the day and the end of the night and compared the profiles to those acquired in short day conditions.