Fig 1.

TBP gene expression in the hypothalamus of photoresponsive and photorefractory hamsters. (A) Mean (±SEM) ETVs of Siberian hamsters exposed to short days for 12 weeks (weeks 20–32; short-day photosensitive, SD) or for 32 weeks (short-day photorefractory, SDR), and of control hamsters exposed to long days for 32 weeks (long-day photosensitive, LD). SDR hamsters initially underwent gonadal regression. In weeks 20–32, SDR hamsters exhibited spontaneous gonadal recrudescence, indicative of short-day photorefractoriness, whereas SD hamsters underwent gonadal regression. LD hamsters sustained fully developed gonads in long days. (*, P < 0.05 vs. LD value.) (B) Pairwise competitive hybridization to a UniGEM cDNA microarray (Incyte Genomics) of fluorescently labeled hypothalamic RNA samples from LD, SD, and SDR hamsters. Control images depict fluorescence indicative of 0-fold (1:1 control; Left) and 3-fold (3:1 control; Center) differences in hybridization between the Cy3 and the Cy5 samples. (Right) Fluorescence of Cy3- and Cy5-labeled samples after hybridization to a probe for mouse TTR in each of the three pairwise microarray experiments. TTR expression was ≈2.5-fold lower in the hypothalamus of SDR hamsters, relative to both LD and SD samples. (C) Relative quantitative RT-PCR assessment of hypothalamic expression of TTR mRNA in photosensitive (LD, SD) and photorefractory (SDR) hamsters confirmed lower expression of TTR in the hypothalamus of SDR hamsters. (D) Expression of TTR, TBG, and albumin mRNAs was lower in the hypothalamus of photorefractory (SDR) hamsters, relative to photosensitive (LD and SD) hamsters.