Comparative Biochemistry and Physiology Part B: Comparative Biochemistry最新文献

The gene products of 60 protein coding loci in Schilbe intermedius were examined by horizontal starch-gel electrophoresis. Electrophoretic analysis, using muscle and liver tissues, revealed polymorphism at 17 (28.3%) of the loci studied. The average heterozygosity (H) was calculated at 0.029 (±0.009) which is less than values obtained for other fish species. These results suggest that measures should be taken to conserve the genetic variation of this species.

The humoral antibody response following anal intubation of a soluble antigenic protein to trout was investigated. The transfer of human immunoglobulin G (IgGh) to the plasma was demonstrated by ELISA assays. The participation of the anterior kidney in plasma clearance of the antigen was shown by an immunofluorescence study. The anterior kidney displayed a proliferation of specific B lymphocytes and differentiation into plasma cells producing anti-IgGh IgM. The peak of plasma specific antibody concentration occurred 30 days after intubation and a second intubation led to another peak 20 days later, whose amplitude was close to that of the primary response.

Glutathione (GSH) regeneration was studied in rabbit erythrocytes which were loaded with calcium using ionophore A23187. Calcium-loading induced by A23187 and various concentrations of CaCl₂ caused a dose-dependent depression in red cell GSH regeneration. The lowered GSH regeneration was mainly due to reduction of ATP level. In an experiment using haemolysate, the effect of calcium per se was negligible, while magnesium strongly affected GSH regeneration by controlling the rate of hexokinase reaction. These results indicate a possibility that cation perturbation, metabolic decay and oxidative damage are all interrelated in the erythrocyte aging process.

No differences were detected in serum IGF-I levels between lean and obese male SHFF/Mcc-fa^cp rats expressing non-insulin-dependent diabetes mellitus (NIDDM). In contrast, serum insulin levels, and blood glucose levels were significantly elevated in obese as compared to lean littermates (P < 0.05), indicating that the obese animals were diabetic. Northern blot analyses of total tissue RNA using labeled cDNAs for IGF-I and IGF-II revealed a decrease in liver and adipose IGF-I mRNA expression in the obese littermates while IGF-II mRNA expression was decreased only in adipose tissue of obese animals as compared to lean littermates.

A strain of high-altitude chickens (Gallus gallus) with a high hemoglobin-oxygen affinity has been found in the Peruvian Andes. The purpose in this work was to investigate the relation of this high affinity with the allosteric regulation of the inositol hexaphosphate effector (IHP). The hemoglobin-oxygen affinity has been determined in phosphate-free hemoglobin solutions before and after the addition of IHP. The results showed that the addition of IHP to the phosphate-free hemoglobin solutions increased the affinity significantly less in the high-altitude chicken (26.3 Torr) than in the sea-level chicken (42.2 Torr) (P < 0.001). It was concluded that the high-affinity hemoglobin is probably dependent on a molecular change affecting the allosteric regulation, although a change in the intrinsic properties of the hemoglobin cannot be discarded.

The presence of FBPase was confirmed in both human and ovine white adipose tissue in metabolically significant amounts. The partially purified enzyme from ovine adipose tissue exhibited kinetic properties very similar to other mammalian FBPases (pH optimum of 7.5, absolute requirement for divalent metal ions and strong inhibition by both AMP and F-2,6-P₂). The micromolar S_0.5 value obtained suggests that the enzyme may be of physiological significance.

In juvenile rainbow trout (Oncorhynchus mykiss) the peak of dietary lipid absorption occurred later at low compared with high temperature. Rapid temperature variations modified plasma concentrations of glucose, lipids and lipoproteins, with no effect on free glycerol. The concentration of these parameters was not affected during the progressive seasonal temperature changes. The plasma concentration of very low density lipoproteins (VLDL) increased by two- to three-fold within two days after the onset of cold acclimation (CA) or warm acclimation, independently of alterations in dietary lipid absorption. The high concentration of VLDL induced an increase in low density lipoproteins (LDL) concentration after several days. CA induced a rapid and transitory decrease in the concentration of high density lipoproteins (HDL) of about 20%. Incomplete successive acclimations resulted in a cumulative effect on the increase of VLDL (10-fold) and of LDL (three-fold). In cold-acclimated trout, the persistent hypertriglyceridemia and high plasma concentration of VLDL observed for several weeks after fasting suggest a long-term increase in the secretion of hepatic VLDL. The results indicated that plasma lipoprotein concentrations appear to be sensitive to the thermal adaptation process in trout exposed to rapid temperature variations.

Hepatic peroxisomal β-oxidation rates were compared in liver homogenates from cows and rats during different nutritional and physiological states. Peroxisomal oxidation in liver homogenates from cows represented 50% and 77% of the total capacity for the initial cycle of β-oxidation of palmitate and octanoate, respectively, but only 26% and 65% for rats. Lactation or food deprivation did not alter rates of hepatic peroxisomal β-oxidation of palmitate or octanoate in cows. Fasting and clofibrate treatment increased rates of total and peroxisomal β-oxidation of palmitate and octanoate in rat liver.

Oxygen binding curves were measured on pigeon red blood cells (RBCs) suspensions, at the temperatures of 25, 30, 37 and 41°C, from pH 7.0 to 8.2, and on pigeon hemoglobin solutions, in the absence and presence of organic phosphates. Data were analysed on the basis of the MWC model. P₅₀ for pigeon RBCs is 46.9 mmHg, at pH 7.4 and 41°C. This low O₂ affinity is due, in part, to the existence of a large pH gradient across the membrane of the RBCs. The overall Bohr effect ($\text{Δ}\text{log}\text{P}{}_{\mathrm{<mtext>m</mtext>}}\text{Δ}\text{pH}$) is –0.44 in the 7.0–8.2 extracellular pH range and increases to –0.70 if intracellular pH is considered (pHi range, 6.8–7.5). A significant pH dependence for K_T and K_R is observed. The maximal Hill coefficient (n_max) for pigeon RBCs never exceeds 3.35 in all the conditions of pH and temperature examined, n_max is slightly higher for RBCs than for hemoglobin dilute solutions. This might denote a diminished solubility of hemoglobin molecule in the physiological milieu, and is not observed for the oxygen equilibrium of human RBCs and hemoglobin solutions. Apart from this, the functional properties of pigeon RBCs are close to those of hemoglobin solutions, under comparable concentrations of protons, Cl^– and organic phosphates, and for the same temperature. The enthalpy change for overall oxygenation of pigeon RBCs is rather small (about – 7 kcal/mol).

The neurocranium of the vieja, Pimelometopon darwini, and the cojinoba, Seriolella violacea, contained 29.5 and 26% lipid (as percent dry weight), mostly as triacylglycerol. The anchoveta, Engraulis ringens; sardina, Sardinops sagax sagax; doncella, Halichoeres dispilis; and mackerel, Scomber japonicus, contained less lipid in the neurocranium (3.3–18.4%). Polyunsaturated fatty acids, dominated by 20:5 and 22:6, were highest for S. violacea (10.6–56.1%) and P. darwini (12.2–28.9%). Lower levels of polyunsaturated fatty acids were found in E. ringens. The major monosaturated fatty acids in all Peruvian fish included 16:1n7, 18:1n9 + 11, and 18:n7, whereas the major saturated fatty acids were 14:0 and 16:0 with lesser amounts of 18:0.