Circadian expression of clock genes in the rat eye and brain.

The light sensing system in the eye directly affects the circadian oscillator in the mammalian suprachiasmatic nucleus (SCN). To investigate this relationship in the rat, we examined the circadian expression of clock genes in the SCN and eye tissue during a 24 h day/night cycle. In the SCN, rPer1 and rPer2 mRNAs were expressed in a clear circadian rhythm like rCry1 and rCry2 mRNAs, whereas the level of BMAL1 and CLOCK mRNAs decreased during the day and increased during the night with a relatively low amplitude.

Cloning and circadian expression of rat Cry1.

In mammals, two types of cryptochrome are involved in the regulation of the circadian rhythm. We previously characterized rat Cry2 and its expression in brain tissue [Eun et al. (2001)].

Cloning and expression of cryptochrome2 in the bullfrog (Rana catesbeiana).

Cryptochromes (CRYs) are non-opsin photoactive pigments that have recently been implicated in circadian photo-entrainment in humans, mice and Drosophila. In order to study the mechanism of circadian rhythm in amphibians, we have cloned and characterized a Rana cryptochrome in the bullfrog. We isolated a cDNA of about 2.

Preferential ligand selectivity of the monkey type-II gonadotropin-releasing hormone (GnRH) receptor for GnRH-2 and its analogs.

Gonadotropin-releasing hormone (GnRH) regulates the reproductive system through the cognate GnRH receptor (GnRHR) in vertebrates. In this study, we cloned a cDNA encoding the full-length open reading frame sequence for green monkey type-II GnRHR (gmGnRHR-2) from the genomic DNA of CV-1 cells. Transient transfection study showed that gmGnRHR-2 was able to induce both c-fos promoter- and cAMP responsive element-driven transcriptional activities, indicating that gmGnRHR-2 couples to both Gs- and Gq/11-linked signaling pathways.

Cloning of ribosomal protein S6 kinase cDNA and its involvement in meiotic maturation in Rana dybowskii oocytes.

Several protein kinases are involved in the meiotic maturation of frog oocytes in order to activate the maturation-promoting factor (MPF). Among these kinases, the 90 kDa ribosomal protein S6 kinase (p90Rsk or Rsk) is directly phosphorylated and activated by the mitogen-activated protein kinase (MAPK). During Xenopus oocyte maturation, the activation of Rsk closely parallels that of MAPK.