Comparative biochemistry and physiology最新文献

1. About 5–10 per cent of the net ¹⁴C photosynthetically fixed by symbiotic chloroplasts in the marine slug Placobranchus ianthobapsus (Gould) was secreted in mucus.

2. After acid hydrolysis of mucus, most of the ¹⁴C was found in galactose and glucose.

1. The cocoon protein of the braconid, apocrite, hymenopteran Macrocentrus thoracicus has been analysed for amino acids.

2. The amino acid composition confirms that the cocoon is made up of a structure protein with the general properties of the arthropod sild fibroins.

3. The implications of the amino acid composition for the interpretation of the molecular organization of the proteins in the cocoon wall, in terms of the X-ray diffraction diagram they give rise to, are commented upon.

1. There is a negative correlation between the bladder urine concentration of Na and Mg in the scorpion fish.

2. Mg excretion and Na reabsorption are sharply increased after intramuscular injection of MgCl₂ solution to migrating juvenile salmonoids and horse mackerel. A close positive correlation is observed between the amount of the reabsorbed Na ions and that of the secreted Mg ions.

3. After inhibition of Na reabsorption by Brinaldix or Lasix, Mg secretion decreased.

4. The data obtained indicate an important role for Na reabsorption in Mg secretion in fish kidney.

1. Separated adult mammalian and avian heart muscle cells were observed to contract and relax spontaneously under conditions which cause contracture of reptilian and amphibian heart muscle cells.

2. The role of catecholamines in imparting resistance to potassium-induced contracture could not be demonstrated with the separated cells, as it has with papillary muscle preparations.

1. ATPase activity has been estimated in heart mitochondria of the fresh-water turtle, Chrysemys picta.

2. This activity is Mg²⁺-dependent and stimulated by the presence of DNP.

3. The pH optima of ATPase activities are 8·5 with Mg²⁺ ions, and 7·4 in the presence of DNP.

4. Differential responses to inhibitors are evident in the presence of added Mg²⁺ ions or DNP, with DNP-stimulated activities being sensitive to a wider spectrum of inhibitors and to the aging process.

5. Bovine serum albumin, but not EDTA, effectively preserves DNP-stimulated ATPase activity during aging. A causal relationship with fatty acids is implied.

6. These data may be used to support either a one or a two enzyme hypothesis, with the latter being favored.

1. Activities of monoamine oxidase (MAO) and dopadecarboxylase (DOPAd) from the brains of mice and goldfish both increased with rise in temperature.

2. Glutamic decarboxylase (GAD) from fish brain differed from mouse brain GAD in decreasing in activity as temperature of the reaction was raised from 20 to 37°C.

3. Heat inactivation of MAO from the brains of both species showed a different pattern of heat inactivation from that of the same enzyme derived from the liver.

1. A urinary polypeptide (FI) from the urine of lipoatrophic diabetics and a similar peptide (BPI) from bovine adenohypophysis induced significant fasting hypoglycemia and increased glucose tolerance in the mouse.

2. The effects of FI and BPI on blood sugar levels were absent in mice pretreated with alloxan and D-mannoheptulose.

3. Plasma immunoinsulin was significantly increased after FI and BPI administration and significantly decreased in mice pretreated with D-mannoheptulose.

4. It was concluded that FI and BPI induction of fasting hypoglycemia and enhanced glucose tolerance is mediated by endogenous insulin release.

1. Lipids in the abdominal fat bodies and the tail of Lacerta vivipara caught in August and September accounted for one third of the dry body weight.

2. When the lizards emerged from hibernation in March and April, lipids accounted for only one sixth of the dry body weight. Half of the loss was from the tail.

1. The oxygen consumption and respiratory rate of the freshwater nemertean, Prostoma rubrum, were determined at 20°C.

2. The mean respiratory rate for forty-nine specimens was 0·700 μl O₂/mg dry wt. per hour (±0·071).

3. Oxygen consumption varied with the 0·478 power of the body weight.

4. A heme-containing pigments is present which may assist in the respiratory process.