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Biomedical subjects

L A Egorova

Publications and source records attributed to L A Egorova.

At least 19 recordsLinked to original sources
PubMed1989

[Peripheral control of the feeding behavior of fresh water mollusks].

Appetitive and consummatory feeding behavior was shown to be initiated by stimulation of different loci. Feeding programs were different in their motor output frequency in P. corneus and L. stagnalis stagnalis. The maintenance of the feeding program was provided by sensory input. In contrast to the insect flight generator, the feeding neuronal program had no peripheral regulation system in freshwater snails, its feeding program being more autonomic from peripheral influences than the flight motor program in insects.

Animals↗
PubMedDate not supplied

[Experimental verification of the results of the mathematical modeling of the process of formation of alpha-amylase-nonproductive mutants of Bacillus subtilis under continous cultivation].

When Bacillus subtilis produces alpha-amylase in the course of continuous cultivation, it is difficult to maintain the activity at a constant level. This may be due to the formation of nonproductive mutants. Individual cells in the population have been analysed in the course of the continuous process. The composition of the population changes depending on time and the composition of the growth medium. Semisynthetic media cause selection of mutants which synthesize the enzyme at a low rate. In contrast, complex media which are more enriched in the sources of carbon and nitrogen induce accumulation of mutants with a high activity.

Amylases↗
PubMedDate not supplied

[Growth and development of extreme-thermophilic bacteria at 70 degrees].

Nine cultures of non-sporeforming gram-negative extreme-thermophilic bacterium Thermus flavus have been isolated from hot springs of Kamchatka. Their optimal growth temperature on a solid potato medium was 70 to 76 degrees C, and on a liquid medium (20 per cent potato broth containing 0.5 per cent peptone and 0.1 per cent yeast extract) 70 degrees C. The minimum time of generation of the bacterium, strain 71, growing on the liquid medium at 70 degrees C, was 52 minutes. Other extreme-thermophilic cultures differ from the strain 71 by a lower growth rate. The maximum biomass yield was 1.96 g per litre of the medium after 6 to 9 hours of growth. The extreme-thermophilic bacteria of Kamchatka are similar to those from the hot springs of Japan.

Bacteria↗
PubMedDate not supplied

[Thermus ruber obligate thermophilic bacteria in the thermal springs of Kamchatka].

The new species of the obligate-thermophilic bacterium Thermus ruber is widely distributed in hot springs of Kamchatka with the temperature of water from 57 to 90 degrees C. The bacterium does not oxidize sulphur. It contains a red carotenoid pigment similar to neuro-sporaxanthine and retrodehydro-gamma-carotene.

Carotenoids↗
PubMedDate not supplied

[Dynamics of the formation of extracellular protease and the ATP pool in a thermophilic strain of Bacillus brevis].

The dynamics of varying ATP concentration was studied in the cells of the thermophilic strain of Bacillus brevis 224 synthesizing a neutral exoprotease. Some irregularities during the primary and secondary growth of the culture corresponded to the changes in the amount of ATP. A sharp decrease (by a factor of ca. 100) in the level of ATP pool was detected in the bacterial cells after 2.5 hours of their exponential growth; their growth ceased and the synthesis of protease was depressed. A decrease in the rate of the enzyme synthesis coincides with an increase in the concentration of ATP in the cells.

Adenosine Triphosphate↗
PubMedDate not supplied

[Distribution of highly thermophilic, nonsporulating bacteria in the hot springs of Tadzhikistan].

Extreme-thermophilic non-sporeforming bacteria belonging to the Thermus genus are widely distributed in hot springs (40-90 degrees C) of Tadzhikistan. Their content was highest (1.8-10(4)--6.0-10(4) cells per gram of ooze) in springs with the temperature of water of 50-60 degrees C, and decreased (to 8.0-10(2)--4.0-10(3) cells per gram of ooze) in springs with the same temperature of water but with a low content of ooze. The number of the cells was even less (5.0-10(2)--4.0-10(3) per gram of ooze) in the surface layers of heated soil, especially at a depth of 2 cm. The lowest number of the cells (0.5-4.0 cells per 1 ml) was found in water at the surface of soil, with the temperature of 96, 93, and 65 degrees C.

Cell Count↗
PubMedDate not supplied

[Acidophilic obligate thermophilic bacteria, Bacillus acidocal-darius, isolated from the hot springs and soil of Kunashir Island].

Obligate thermophilic acidophilic cultures of Bacillus acidocaldarius were isolated from hot springs and soil of the Kunashir Island (the Kuril Islands) and Southern Sakhalin; their optimum temperature of growth is 65 degrees C and pH is 3.3--4.0. It has been shown for the first time that these organisms can be isolated from springs with either acidic or neutral and weakly alkaline pH values.

Bacillus↗
PubMedDate not supplied

[tRNA-methylase study of the extreme thermophile, Thermus flavus].

tRNA methylases were studied in the extreme thermophilic culture of Thermus flavus, strain 71. Like E. coli, the culture contained only those tRNA methylases which catalysed the formation of m1A and m7G. Mg2+, Ca2+ and Na+ ions activated tRNA methylases of Thermus flavus in the series Mg greater than Ca greater than Na while Mn2+ ions inhibited the enzyme. The activity of tRNA methylases was higher in T. flavus than in E. coli, and required less protein and time for exhaustive methylation of tRNA preparations. The overall activity of methylases in T. flavus at 70 degrees C was 5-6 times higher than at 40 degrees C; the elevation of temperature had different effect on various methylases: the activity of m1A methylase increased 13-fold whereas that of m7G methylase only twofold.

Chemical Phenomena↗
PubMedDate not supplied

[Amylase formation in a periodic and continuous culture of Bacillus subtilis].

The dynamics of alpha-amylase production by two strains of Bacillus subtilis (A32 and A32.6) was studied under periodic and continuous conditions of cultivation on a chemically defined medium and on a natural medium. In the periodic culture, the highest activity of the enzyme was found during the stationary growth phase. In the conditions of chemostat, as the dilution rate from 0.05 to 0.15 hr-1, the activity of amylase remained at the same, high level for a certain lapse of time and then decreased. The rate of the decrease of alpha-amylase activity depended on the dilution rate.

Amylases↗