Molecular mechanisms regulating animal seasonal breeding in response to changing photoperiod are not well understood. Rapid induction of gene expression of thyroid-hormone-activating enzyme (type 2 deiodinase, DIO2) in the mediobasal hypothalamus (MBH) of the Japanese quail (Coturnix japonica) is the earliest event yet recorded in the photoperiodic signal transduction pathway. Here we show cascades of gene expression in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone. We identified two waves of gene expression. The first was initiated about 14 h after dawn of the first long day and included increased thyrotrophin (TSH) beta-subunit expression in the pars tuberalis; the second occurred approximately 4 h later and included increased expression of DIO2. Intracerebroventricular (ICV) administration of TSH to short-day quail stimulated gonadal growth and expression of DIO2 which was shown to be mediated through a TSH receptor-cyclic AMP (cAMP) signalling pathway. Increased TSH in the pars tuberalis therefore seems to trigger long-day photoinduced seasonal breeding.

Prorenin is the inactive precursor of renin (EC 3.4.23.15), which is a key enzyme in the regulation of blood pressure and electrolyte balance. Prorenin has a prosegment with 43 residues attached to the N terminus of mature renin with 339 -341 residues (1-4). The prosegment has been considered to associate with mature renin to prevent interaction with angiotensinogen, its macromolecular renin substrate (5-7). Prorenin does not proteolytically self-activate like pepsinogen, and its blood circulating level is 10 times higher than that of mature renin (8, 9). Some investigators have recently proposed that prorenin is a useful marker of diabetic microvascular complications and Wilms' tumor (11-13). However, much information regarding prorenin is unclear or lacking. The intrinsic activation enzyme, the activation mechanism in vivo, and its physiological role and source in the circulation remain unknown.Prorenin has reportedly been activated in vitro by endopeptidases such as trypsin and cathepsin B (3, 14, 15) and has also been non-proteolytically activated under acidic pH and/or low temperature (17)(18)(19)(20)(21)(22). We recently showed that specific antibodies to the prosegment (L 1P PTDTTTFKRIFLKR 15P ) activated human prorenin non-proteolytically (23). More recently, a renin/prorenin receptor was found in several tissues with nonproteolytically activated renin as well as prorenin (24). These non-proteolytic activations have generally been thought to arise from a conformational change of the prorenin molecule in vivo.The inactivation mechanism for prorenin has been reported using recombinant prorenins mutated at single to triple residues in the prosegment that formed ionic bonds (25-27) or a hydrophobic bond (27) between the prosegment and mature renin. Advanced research on the role of the prosegment in the non-proteolytic activation of prorenin may provide clues to solving those problems. Recently, we found that the acid activation rate of rat prorenin was less than one-fifth of that of human prorenin (4), and the speed of this process was only dependent on the amino acid sequence in the prosegment with 43 amino acid residues (28). These results led to our working hypothesis that there was an essential region in the N-terminal side of the prosegment for non-proteolytic activation of prorenin. In this study, we propose a hypothesis that there are two key regions, "gate" and "handle," in prorenin non-proteolytic activation using several kinds of prorenin-specific antibodies. EXPERIMENTAL PROCEDURESDesignation of Antigen Peptides-Antigen peptides in several regions of the prorenin prosegment were designed on the basis of the primary structure of the prosegment and the stereo structure of human prorenin predicted by the homology modeling method, as shown in Fig.

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The present study was done to reveal how egg white is taken up by embryonic tissues, the pathway through which egg white is transported, and the location where it is digested during the development of the quail Coturnix japonica. Antiserum against quail ovalbumin was raised in rabbit and used as a probe. By immunoelectron microscopy, the uptake of ovalbumin on a small scale by receptor-mediated endocytosis was observed in the ectodermal cells of the yolk sac on days four to seven of incubation. The uptake of egg white on a large scale by fluid-phase endocytosis took place in the cells generally referred to collectively as the 'albumen sac'. The ovalbumin was transported through the albumen sac into the extraembryonic cavity during days eight to 10, and then into the amniotic cavity through the amnion approximately on day 10. Ovalbumin was present in the intestinal lumen on days 11 and 14, but it was not digested in the intestinal epithelial cells. The ovalbumin was detected in the yolk of embryos after day 10. Immunoblot testing, as well as a fluoroimmunoassay, revealed that the location where the amount of ovalbumin was highest changed chronologically from the extraembryonic cavity on day 10 to the amniotic cavity on day 11, the intestinal lumen on day 12 and then to the yolk on day 13. Several low molecular proteins which cross-reacted with the antiserum were observed in the extracts of the yolk. The reaction producing these proteins depended on low pH (approximately 3.0) and was inhibited by pepstatin A. The ovotransferrin was similarly digested. These results indicate that egg white is, for the most part, transported through the albumen sac to the yolk via the extraembryonic cavity, the amniotic cavity, and the intestinal lumen, and is digested in the yolk by aspartic proteinases.

The structure and mineral composition of eggshell cuticles were studied in species of birds. The approximate thickness of the cuticle layer at the top of shell columns was about m in the Red Junglefowl ( ), about m in the White Pelican ( ), about m in the Japanese quail ( ), about m in the Greater Flamingo ( ) and about m in the Humboldt Penguin ( ). The matrix of the cuticle layer decalcified with EDTA was composed of vesicles in a variety of sizes in all birds. Major elements in cuticle materials detected by X-ray microanalysis were O, C, Ca and P, and their percentage numbers of atoms decreased in this order. The concentration of P was significantly higher in the cuticles of the quail, flamingo, and penguin than in those of the junglefowl and pelican. Ca mapping on electron-microscopic images showed strong signals in the shell layer and weaker ones in the cuticle layer, whereas P mapping showed that signals were mostly confined in the cuticle layer. X-ray di raction analyses on the inside of the shell layer showed a profile of calcite crystals of calcium carbonates in all birds. In the cuticle materials, the profile was of calcite in the junglefowl, and a mixture of calcite and vaterite in the pelican. The profiles in cuticle materials of the quail, flamingo and penguin showed no specific signals, indicating that mineral compounds are amorphous in these forms. It was suggested that the diversity of mineral structures in the cuticle layer is caused by the presence of phosphorous, in addition to the structure of the cuticle matrix.