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

Hemagglutination of normal and enzyme-treated red blood cells and its inhibition, in vitro adherence to porcine caecal mucus and kinetic properties of neuraminidase were carried out with Tritrichomonas suis and T. foetus. All tested strains adhered extensively to porcine caecal mucus in vitro and agglutinated human (A₁, A₂, B and O), rabbit, porcine and hen red blood cells. Different inhibitors were efficacious in hemagglutination activity (HA) tests using neuraminidase treated and untreated red blood cells. The Scatchard plot showed an independent type of cooperativity in porcine strain 41, while in bovine strain KVC-1, a positive type of cooperativity was observed.

The electrophoretic banding pattern of hemocyanin monomers in blue crabs caught in natural waters indicates that the phenotypes associated with normoxia or hypoxia in the laboratory can also be found in those conditions in nature. PAGE of pure fractions of 1 × 6-mers isolated by HPLC revealed only the two invariant plus one slightly variable band. In contrast, the 2 × 6-mer fraction contained those three plus the three highly variable bands. These results support the hypothesis formulated by earlier workers that monomers other than the linker chains stabilize the 2 × 6-meric conformation. However, correlations of 2 × 6-mer content with various combinations of monomer contents suggest that one of the three variable chains has little or no stabilizing effect.

Luminometric methods show that melanosomes in liver pigment cells of Rana esculenta L. have endogenous ATP and ATPase activity. The K_m value of ATPase is 0.42 × 10⁻⁸ mol/l at pH 7.0. Inhibition of ATPase by antimycin and by ouabain is not effective. In the presence of an excess of ADP and Pi, ATP synthesis was observed.

High glycogen content and abnormal mitochondria have been seen in muscles from RN carrier pigs in a previous work. Glycogen synthase, branching enzyme, phosphorylase and debranching enzyme activities, and mitochondrial characteristics were studied in normal and RN⁻ carrier pigs. Branching enzyme activity was higher ($\text{P < 0.01}$) and glycogen synthase activity tended to be higher in longissimus dorsi muscle from RN⁻ carrier pigs compared to normal pigs. There were no differences in the activities of either phosphorylase and debranching enzyme between both types of pigs. Citrate synthase activity and mitochondrial respiration were slightly higher in muscle from RN⁻ pigs compared to normal pigs. Glycogen content in muscle from RN⁻ pigs could result from the imbalance between anabolic and catabolic enzyme activities of glycogen metabolism. The higher specific activity in mitochondria of RN⁻ pigs muscle might be the compensatory effect of an abnormal glycolytic metabolism.

Various monosaccharides, including ribose, mannose, galactose, and urea, in combination with glucose, were studied to determine their efficacy in supporting the formation of pyruvate, lactate, 2,3-diphosphoglycerate and ATP in Rana ridibunda erythrocytes. Lactate formation was found to increase during the course of incubation in the presence of all the substrates. None of the studied substrates maintained cellular ATP levels. About 0.36 μmole of lactic acid per hour was produced for each μmole of ribose that was metabolized. The presence of 1 mM Na-iodoacetate accelerated the loss of ATP and lactate in the presence of either glucose or ribose. Additionally, ouabain suppressed lactate formation from ribose alone, as well as in combination with glucose. From the metabolic substrates studied, ribose was shown to be the most efficient substrate to support Rana ridibunda erythrocyte metabolism. Mannose, galactose and urea may also be used as alternative metabolic substrates by Rana ridibunda erythrocytes.

An ammoniotelic freshwater teleost, Heteropneustes fossilis, tolerated ambient ammonium chloride concentration up to 75 mM. Ammonia accumulated significantly in all the tissues within 7 days of treatment and the concentration remained high throughout the 4-week period of treatment. The activity of enzymes of the ornithine-urea (o-u) cycle were induced within 7 days, and thereafter remained high in both the liver and kidney of the fish. Urea accumulated significantly in various tissues simultaneous with the induction of o-u cycle enzymes. Accumulated ammonia induced the activity of the enzymes of the o-u cycle for its metabolic conversion to urea. This helped the freshwater fish to avoid toxaemia and to tolerate high concentrations of ammonia in the ambient medium.

Extracellular iron-binding proteins function in iron transport, iron scavenging and bactericidal activity. To determine whether the levels of chicken iron-binding proteins are altered during an immune challenge, young broiler chicks and 40-week-old hens were injected with lipopolysaccharide (LPS). Serum transferrin and liver mRNA for serum transferrin increased at 24 hr after injection. Increased levels of serum transferrin and hepatic mRNA for serum transferrin define chicken serum transferrin as an acute-phase protein. Magnum mRNA for ovotransferrin decreased 24 hr after the immune challenge in hens. Hens had also stopped ovulating, suggesting that synthesis of all egg proteins was decreased.

The phosphorylation of 100 and 170 kDa proteins was increased in response to fertilization in eggs of Rana dybowskii. There was a transient increase of inositol 1,4,5-trisphosphate and diacylglycerol in fertilized eggs. Treatment of 0.2 mM CaCl₂ in unfertilized egg homogenate also phosphorylated the 100 and 170 kDa proteins. Data suggest that the sperm signal increases IP₃ content in egg cytoplasm, triggering Ca²⁺ release from internal storage into cell matrix to activate Ca²⁺-dependent protein kinases, necessary for the early embryonic development.

Sera from human subjects affected by autoimmune connective tissue diseases and containing antiribosomal autoantibodies were used to analyze by immunoblotting ribosomal proteins from trout (Oncorhynchus mykiss) liver, mussel (Mytilus edulis) hepatopancreas and whole fly maggots (Calliphora vomitoria). As usual in medical analysis of autoantibodies, the reference antigen preparation was extracted from rat liver. With the used sera, six known ribosomal proteins from rat liver were characterized: P₀, P₁, P₂, p30, p25 and p20. These six proteins were all targeted in trout; moreover an important 40 kDa fraction, undetectable in rat pattern, was seen. p30 and p20 were undetected in mussel and fly maggot; but p25, undetected in mussel, is clearly characterized in fly maggot. The interest of these data to infer phylogenic relationships is discussed.