[Localization of aldolase activity in the embryos of loach].

The activity of aldolase was determined in different parts of the loach (Misgurnus fossilis L.) embryo at the stages from the formation of axial organs till the beginning of embryonic movements (from 19 till 38 hrs of development at 21.5 degrees).

[Time of the action of genes controlling the activity of aldolase in embryonal development of groudling].

The time of action of the genes controlling the decrease of aldolase activity (21-23 hrs of development) and its subsequent increase (23-36 hrs) was determined by means of inactivation of the nuclei by actinomycin or heavy doses of irradiation at succesive developmental stages. There exist two distinct periods of gene activity; the former (15-18 hrs) determines the rapid fall of maternal aldolase activity and the latter (21-27 hrs) its subsequent replacement by embryonic aldolase. This result is confirmed by the data concerning the changes in aldolase heat resistance in the hybrids of the loach and tropical cyprinids.

[Heat resistance of aldolase of the hybrid embryos of sea urchins Strongylocentrotus droebachiensis and S, intermedius].

The time of expression of the genes controlling aldolase has been studied in the hybrid embryos female Strongylocentrotus droebachiensis X male S. intermedius. The enzyme heat resistance estimated by the temperature of 50% inactivation following the exposition for 30 min (T50) was used as its genetic marker.

Expression of aldolase-controlling genes in hybrid fish embryos. Use of thermostability as a genetic marker.

A new method based on differences in protein thermostability has been proposed for studying genetic control of protein synthesis during development. The effectiveness of this method was checked for aldolase, whose thermostability was established from the temperature required for 50% inactivation after heating for 30 min (T50%). Eggs from a relatively cryophilic species, the loach, were fertilized with sperm from warm-water aquarium fish: the danio, barb, rasbora, and goldfish.