Comparative biochemistry and physiology最新文献

1. Repeatedly bred rats develop arteriosclerosis spontaneously.

2. Lactation and weaning cause exacerbation of the vascular changes.

3. Mucopolysaccharides, collagen, elastic tissue and calcific changes are predominant features of the arteriosclerosis.

4. The adrenal steroids are implicated in conditioning aortic enzyme changes, e.g. beta-glucuronidase, which make for premature arterial disease in breeder rats.

1. The gross chemical composition of the body was determined in one random bred line and three inbred lines of house mice (Mus musculus).

2. The variability in relation to their respective means of body weight, and of each constituent except fat, was similar in each line.

3. Analysis of variance revealed highly significant differences between lines in all constituents, and in body weights.

4. Analysis of covariance using body weight as covariate revealed no difference between lines in content of fat-free combustible matter, significant differences in fat content, and highly significant differences in water and ash contents.

5. The genetic and physiological implications of these results are discussed.

1. Microelectrode unit recordings obtained from the metathoracic ganglia of flying locusts did not reveal any flight rhythm interneuronal pacemakers. If such units are present, they are not accessible for detailed electrophysiological examination.

2. The detection of units responding to tactile and visual stimulation whose impulse discharge patterns were coupled with the flight rhythm provides evidence for the diffuse nature of the neural network which generates the flight pattern.

1. With adequate stimulation the compound action potentials of the cerebropedal and cerebropleural connectives of the prosobranch Scutus breviculus were found to have components with conduction velocities ranging from 0·64 to 0·13 m/sec.

2. Q₁₀ values for conduction velocities measured between 13 and 19°C were found to fall within the range 1·33–1·75.

3. The conduction velocities were also measured with the connectives surrounded by artificial media with cation concentrations the same as those measured in the blood of Scutus specimenswhich had been kept in diluted sea water.

1. The variations in prothrombin time, Factors V and VII was studied in nine species.

2. The changes in prothrombin time, Factors V and VII was studied during the development of rats and swine.

3. In rats and swine, the prothrombin time decreased post partum, while the Factor V and VII content increased.

1. The blood osmotic pressure in the terrestrial isopod Porcellio scaber varies inversely with the acclimation temperature (as measured at 3, 23 and 30°C). This species also has decreasing osmotic pressures with increasing size.

2. Between 23 and 30°C smaller animals did not show any difference in their blood oxmotic pressure, while in larger animals the blood concentration remained unchanged between 23 and 3°C.

3. Moulting animals as well as ovigerous females have lowered osmotic pressures. There was no influence of sex on the osmotic value in intermoult animals.

4. The blood concentration of Oniscus asellus was not related to body size when measured at 23°C.

5. Some ecological and metabolic implications of these findings are discussed.

1. Erythrocyte free preparations of Plasmodium knowlesi were incubated with various species of glucose ¹⁴C and dyruvate ¹⁴C. End products and isotope distribution were examined. It was found that:

2. The quantities of glucose carbon incorporated into CO₂ keto acids and lipids were low and of doubtful significance.

3. Volatile acids, neutral volatile compounds and lactate comprised the major end-products of glucose dissimilation by P. knowlesi. Carbon from ¹⁴C labeled species of glucose and pyruvate were rapidly incorporated into both the neutral and acid volatile fractions. Acetate and formate have been identified as important components of the acid volatile fraction. Small amounts of succinate have been isolated, but can account for only a minor portion of the glucose carbon utilized.

4. Pyruvate-¹⁴C was utilized rapidly by P. knowlesi preparations, the methyl carbon was incorporated into acetate while the carboxyl carbon was not, as would be predicted by known pathways.

1. A device was designed for accurate and automatic measurement of the frequency/temperature relationship of the electric discharge in a weakly electric fish, Eigenmannia sp.

2. The observed hysteresis for increasing and decreasing temperatures was in the range of 2–4 per cent, maximal 10 per cent.

3. The low values of hysteresis explains, in this respect, the negative results of Enger & Szabo (1968) who used measuring methods which were not sufficiently accurate.

1. Free amino acids of the haemolymph of a millipede Spirostreptus asthenes and a centipede Ethmostigmus spinosus were determined by the methods of Folin and Spackman et al.

2. Seventeen amino acids (alanine, arginine, aspartic acid, cystine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenyl alanine, proline, serine, threonine, tyrosine and valine) were present in high concentrations.

3. The presence of cystine is suggested to be characteristic of myriapods.

4. Total concentrations of free amino acids were comparable to those of the primitive hemimetabolus insects.

1. Arrhenius plots for succinate oxidation by mitochondria from homeothermic animals indicate a phase change at approximately 23°C with an increased activation energy below this transition temperature.

2. Similar plots for poikilotherms are continuous and linear with no change in activation energy over the entire range from 4–30°C.

3. These results are suggested to be related to a direct response to temperature causing a configurational change of the membrane associated enzyme proteins induced by a phase change in the membrane lipids in homeotherms not observed in poikilotherms.