Comparative biochemistry and physiology. Comparative physiology最新文献

1. To evaluate growth-promoting potencies of bovine insulin, bovine growth hormone (bGH), and recombinant human insulin like growth factor (rhIGF)-I and -II in the chicken, phenylalanine extraction from a synthetic serum-free culture medium into whole-embryos was measured. 2. The chicken embryos at 7 days of age were cultured in a rotatory embryo culture apparatus under a gas phase of 95% O2 and 5% CO2 at 37 degrees C for varying periods of time, and the change in phenylalanine contents in the medium was determined fluorimetrically. 3. Bovine insulin enhanced the phenylalanine extraction when added to the medium at 250 ng/ml whereas no significant change was observed below this concentration. 4. Intact bGH did not show any significant effect on the phenylalanine extraction in its intact form at the concentrations tested. However, bGH partially digested with trypsin increased the phenylalanine extraction. 5. The rhIGF-I enhanced the phenylalanine extraction significantly at 50 ng/ml with no significant increase below this level, whereas rhIGF-II showed no significant increase in phenylalanine extraction at any doses tested. 6. It was concluded that the whole-embryo culture was a quick and convenient system for searching physiologically active compounds that may have growth-promoting potency in the chicken.

1. The effect of 3-days fasting and the subsequent 3-days refeeding on total messenger ribonucleic acid (mRNA) content in the liver of chicks was investigated. 2. Body weight and liver weight were decreased by fasting, and were increased by refeeding to higher than initial values. 3. There was no influence of fasting and refeeding on RNA and mRNA contents per unit liver weight. 4. Total RNA content in the liver was decreased by fasting and was increased by refeeding to higher than the initial level. Fasting tended to reduce total mRNA content in the liver, and the following refeeding increased it significantly up to the initial level.

1. Glycogen is accumulated in the liver of rats given a histidine-excess diet. 2. In order to know the regulatory point, the activities of eight hepatic key enzymes in the carbohydrate metabolism were measured after feeding either a basal or a histidine-excess diet for 0, 3 and 7 days. 3. The active glycogen synthase level was about 2.6- and 3.0-fold higher after feeding for 3 and 7 days, respectively, but the total activity of this enzyme was not affected after feeding for 3 days and was increased after feeding for 7 days. 4. The active glycogen phosphorylase, glucose 6-phosphatase and pyruvate kinase activities were significantly decreased, and fructose 1,6-bisphosphatase activity was increased on a histidine-excess diet for 3 days. 5. Thus, of these enzymatic changes, mainly the enhancement of active glycogen synthase might lead to the substantial accumulation of hepatic glycogen. 6. The in vivo incorporation of radioactive glucose into liver glycogen was stimulated in rats given a histidine-excess diet.

1. Changes in body composition during starvation were compared between germ-free (GF) and conventionalized (CVL) chicks in experiment 1. At 8 days of age, the GF birds were divided into two groups, i.e. GF and CVL groups. The CVL birds were inoculated with faeces from conventionally reared birds. Until 14 days of age, both birds were fed a diet ad lib. and thereafter starved for 6 days. 2. Nitrogen loss during starvation was significantly lower in CVL birds, though the reverse was true for water loss. Fasting heat production was comparable between two environments. 3. Influence of the gut microflora on body weight and nitrogen losses during starvation was investigated in birds prefed diets high or low in dietary protein in experiment 2. 4. No significant effect of the gut microflora was observed in body weight and nitrogen losses. Body weight was severely reduced in birds prefed the high protein diet and nitrogen loss was lower in birds prefed the low protein diet.

1. The influence of the gut microflora on lipid metabolism was investigated in germ-free (GF) and conventional (CV) laying Japanese quail. 2. Serum and egg yolk cholesterol concentrations showed comparable values in both GF and CV environments. 3. The fatty acid composition of liver lipids was modified by the presence of gut microflora. Notably, in the presence of the gut microflora, proportion of oleic acid was reduced and conversely, stearic and linoleic acids were enhanced. 4. In egg yolk lipids, the proportion of myristoleic and palmitoleic acids was significantly lowered and that of stearic acid was significantly enhanced by the presence of the gut microflora, though the difference was very small. 5. It was suggested that oleic acid could be easily either hydrogenated to stearic acid or desaturated to linoleic acid by the action of the gut microflora in Japanese quail.

1. Rats were fed with diets containing orotic acid with dietary fibers to induce alteration of lipid metabolism and cytoplasmic enzyme activities in the livers. Concentrations of blood glucose, serum insulin and free fatty acids (FFA) were measured. 2. In CP (cellulose + orotic acid) group compared to basal (cellulose - orotic acid) or CBH (corn bran hemicellulose + cellulose + orotic acid) groups, glucose-6-phosphate dehydrogenase, pyruvate kinase and ATP citrate lyase activities and FFA concentration were decreased according to lipid accumulation of livers. 3. In the CBH group, glycerokinase activity was higher than basal group.

1. Digestibilities of feed, and transit and retention time of fluid and particle digesta marker measured in nutrias (Myocaster coypus) and guinea-pigs (Cavia porcellus) fed on a diet containing 50% alfalfa. 2. The digestibility of fibre was higher in the nutria, along with the longer retention time of digesta. 3. The liquid and particle marker were similarly excreted, suggesting no separation mechanism in the gastrointestinal tract of both the animals. 4. The apparent digestibility of protein in the nutria was superior to the guinea-pig and other small hindgut fermenters, suggesting that the contribution of coprophagy on protein nutrition of nutrias is significant.

1. Dye-coupling among taste disk cells in the bullfrog fungiform papillae was examined histologically by injecting a fluorescent dye (Lucifer yellow) into the cell, and the effects of the dye-coupling on depolarizing responses induced by taste stimuli were studied electrophysiologically. 2. With dye injection into a taste cell, dye-coupling was found between taste cells (23%) or between taste cell and supporting cell (28%). With dye injection into a supporting cell, dye-coupling was found between supporting cells (34%) or between supporting cell and taste cell (27%). 3. Depolarizing responses recorded from either a taste cell or a supporting cell to stimulation with 0.5 M NaCl or 10 mM quinine-HCl were the same in amplitude whether the dye-coupling to another cell was present or not. On the other hand, depolarizing responses recorded from a taste cell for 0.5 mM acetic acid became significantly larger when dye-coupled to a supporting cell. 4. It is concluded that gustatory transduction for acid stimuli is influenced by supporting cells coupled to taste cells.

1. Muscle wet weight and glucose uptake were measured in female Wistar rats 7 and 14 days after unilateral ligation and section of the artery. 2. Following the induction of arterial insufficiency, muscle wet weight decreased significantly in the extensor digitorum longus (EDL), but not in the soleus muscle (Sol). 3. Muscle glucose uptake per wet weight increased significantly in EDL after arterial insufficiency, but not in Sol. 4. It is suggested that arterial insufficiency influences the metabolic control of fast muscle via anoxia as a main etiologic factor.

1. Age-related changes in glutathione (GSH) content of eye lenses were investigated in senescence-accelerated mouse (SAM) and C57BL/J mice. 2. The decrease of GSH content with aging is markedly observed in SAM strains. 3. The oxidized glutathione (GSSG) content of eyes increased significantly with aging in SAM. 4. Ophthalmic changes, including cataract, increased with age in SAM alone. 5. The decrease of GSH content and the increase of GSH oxidation may be involved in the pathogenesis of cataract in SAM.