The correlation between the heat resistance of the zygotes of the common frog Rana temporaria and its embryos at different developmental stages

A study has been made of a correlation between the heat resistance of zygotes and embryos of the same clutches at different stages of development of Rana temporaria L. The embryos were incubated at 19 degrees C, the injurious temperature being 37 degrees C. As criterion of heat resistance served the time of the injurious temperature action which leads by the ++stra of cleavage to a 50 per cent elimination of embryos (LD50). The correlation in question has been evaluated by the rank correlation coefficient (rho). The correlation between the heat resistance of zygotes and embryos at the start of gastrulation (stage 11) was moderate (rho = 0.47). At one of neurulation stages (stage 22) this correlation was weak (rho = 0.207), to become rather high just before the cleavage (stage 28, rho = 0.63). It is assumed that the thermal selection of zygotes, i.e. of the organism at the cellular stage of development, may be oriented to result in the survival of embryos, which just before the cleavage will show both elevated heat resistance and high heritability of this character.     

Method of repeated determination of muscle heat resistance in individual frog specimens]

The heat resistance of m. interphalangialis of fingers of hind extremities of Rana temporaria L. has been determined. No significant differences were observed in the average values of the heat resistance in fingers 3 and 5 isolated simultaneously. In separate individuals there exists a high positive correlation between the heat resistance levels of these muscles. When the muscles are isolated successively rather than simultaneously, the correlation degree depends on the time lapse between their isolation from the organism. With 1-14 days lapse the correlation breaks down, to be restored after a longer interval. Taking this into account, a method of successive isolation of m. interphalangialis can be used when studying the dynamics of muscle resistance within the same organism.     

Relationship between Bacillus sphaericus spore heat resistance and sporulation temperature

Bacillus sphaericus 9602 was grown in batch culture at various temperatures. At 10°C and 12°C the maximum sporulation yield was <10%, while at 15°C, 20°C and 30°C, a sporulation yield of >95% was achieved. However at 40°C B. sphaericus grew only vegetatively. The heat resistances (D values at 90°C) of spores grown at 15°C and 20°C were significantly higher than those grown at 30°C.     

Effect of temperature and non-temperature selection of male parental gametes on the heat resistance of the ciliated epithelium in frog progeny

Positive correlation was observed between the thermostability level of the parental sperm and that of the ciliary epithelium in the frog Rana temporaria. It is suggested that this correlation is realized by a special mechanism irrespective of the functional profile of the somatic cells.     

Dynamics of various integral characteristics of individual changes in ethanol resistance in isolated muscles of grass frog]

A study was made of the dynamics of the mean level of toxic ethyl alcohol (EA) (3.5 M) resistance, of the correlation between the initial individual level of this resistance and the value and shifting direction of the level, and of the pattern of correlation between levels of resistance in the pair sartoria muscles and variability of resistance level in muscles, kept in EA subtoxic solutions (0.87 and 1.09 M) for 240 min. Two-phase changes in the mean level of resistance in muscles were revealed that involved its increase by 20% within 60 min of maintenance in both EA concentrations, and followed by a decrease of this level by the end of observation. On the first steps of muscle maintenance in EA subtoxic solutions, a negative correlation was noticed between the initial level of resistance and the value and direction of its shifting, in addition to narrowing the range of variability of this level in muscles. All these events were accompanied by a decrease or fluctuations in the correlation coefficient between levels of resistance in the pair muscles. By the end of the experiment, the range of variability of the level of resistance was seen to increase, and the earlier negative correlation between the initial individual level of resistance and the value and direction of its shifting appeared to change for a positive one. Both processes preceded the decrease in the mean level of muscle resistance.     

Effect of thermal selection of the male gametes on the resistance to temperature and chlorophos of the body and muscles in tadpoles of the common frog

A study was made of the effect of thermal selection of parental spermatozoa on the heat resistance of the whole organism and of muscles in progeny of Rana temporaria, as well as of the organismal resistance to pesticides (0.0025 M chlorophos). The thermal selection of spermatozoa was performed by exposing their suspension to 36 degrees C for 30-40 minutes. With tadpoles, the resistance of muscles to 38 degrees C, was determined, in addition to the resistance of the organism to 34 degrees and to 0.0025 M chlorophos. The results of selection were stage--specific: at stages of growth (stages 39, 42, 50) the heat resistance of the organism was lower and that of muscles was higher than in controls. At the stage of metamorphosis proper (stage 52) the heat resistance of both the organism and muscles increased. The thermal selection of parental spermatozoa exerted no effect on the resistance of the progeny to 0.0025 M chlorophos.     

Effect of cold acclimatization of grass frogs on the heat resistance of their somatic muscles in summer]

During cold acclimation (+5 degrees C) of the grass frog Rana temporaria L. changes in heat resistance were observed for six of seven skeletal muscles examined. Changes in the resistance of different muscles were directed differently. Low-resistant muscles demonstrated an increased resistance, wheras high-resistant muscles showed a decrease resistance. Within 24 hours of acclimation, all the muscles demonstrated totally decreased heat resistance. By the end of acclimation (30 days), the resistance of muscles increased to approach the initial level. On the background of those situation changes, seasonal changes in resistance of muscles proceeded.     

Studies on the osmotic resistance and the viability of amidinated erythrocytes]

The present studies are concerned with properties of amidinated erythrocytes. The reactions of dimethyladipimidate with proteins in solution and red blood cells, respectively, result in an intermolecular cross-linking. Following an amidination of human serum albumin or human gamma-globulin cross-linked products of increased molecular weight have been demonstrated by polyacrylamide gel and immune electrophoresis. Human erythrocytes previously amidinated intensely, exhibit a restricted motility of membrane particles and cross-linked hemoglobin. Intensely amidinated erythrocytes are resistant against distilled water, and they do no longer agglutinate. The findings presumably indicate an increased permeability of the amidinated red cell membrane. The glycolytic activity was found to be normal in moderately amidinated erythrocytes. In comparison with normal red blood cells, previously moderately amidinated erythrocytes of the rat become sequestered more quickly after re-injection into the vascular system.     

Changes in primary heat sensitivity of rhabdomyosarcoma PA-2 cells in rats during selection for heat resistance

Using the technique of multistep selection, a thermoresistant substrain (TR RA-2T45) was obtained from a rhabdomyosarcoma RA-2 strain. The cells of this substrain retain the ability to form lung metastasis after a 20 minute treatment at 45 degrees C in vitro. The selection of cells for their ability to retain their reproduction activity is accompanied by the increase in their primary thermoresistance. The increased reproductive thermoresistance and primary thermoresistance of the selected cells is hereditary stabilized. Cells of both original strain and its substrain are capable of thermal tolerance, which makes perspective the selection for further increase in thermoresistance in RA-2T4t cell population.