[Genetic, molecular, and humoral endocycle-regulating mechanisms].

The review presents data on the molecular genetic mechanisms controlling endoreduplication. The issues concerning the activity of the main cycle cell regulators, such as cyclins, cyclin-dependent kinases, and their inhibitors, under conditions of a modified cell cycle of polytene cells are considered. Specific features of regulation at the replication origin points and the role of hormones and phytohormones in the ontogenetic control of endoreduplication are analyzed.

[Effect of culture density on the polyteny degree of giant chromosomes in inbred lines and hybrids of Drosophila melanogaster].

The influence of culture density and genotype on the polyteny degree of giant chromosomes (PDC) in Drosophila melanogaster was investigated. The reliable depression of the polytene chromosomes endoreduplication function under increased culture density was revealed. The essential dependence of the PDC on the genotype was shown.

[Influence of the genotype on the polytene chromosome puffing and bioelectrical properties of cellular nuclei of Drosophila melanogaster treated with ecdysone in vivo and in vitro experiments].

Activity of polytene chromosome puffs at the 0-hour prepupae stage and bioelectric properties of cellular nuclei of salivary glands were investigated under the influence of the hormone 20-OH-ecdysone in vitro in highly inbred selected lines LA (low activity) and HA (high activity) and their F1 hybrids LA x HA and Ha x LA. The inadaptive line LA differs from the line HA by the smaller size of the puffs. The hybrids exceed the best parental line by the size of the majority of the investigated puffs.

[Effect of parental age on endoreduplication of giant chromosomes and some quantitative traits in Drosophila melanogaster descendants].

We studied the influence of parental age on the degree of polyteny of giant chromosomes and expressivity of mutation eyeless in Drosophila melanogaster descendants. The parental age equal to six days exerted an adverse effect on the function of endoreduplication of giant chromosomes in strain eyeless. The highest degree of polyteny was observed in descendants of four- and ten-day imago.

[Influence of genotype on endoreduplication of giant chromosomes and expressivity of character eyeless in Drosophila melanogaster].

In Drosophila melanogaster lines LA (low activity), HA (high activity), and Oregon-R (wild type), the effect of genetic background on endoreplication in giant chromosomes of salivary glands, fecundity, and expression of mutation ey was studied. The degree of chromosome polyteny and the number of adult flies in saturated lines eyHA, eyBA, and eyOr were significantly higher than in the original lines. The degree of chromosome polyteny was correlated with fecundity.