[DNA reduplication cycle during chromosome polytenization in the salivary gland cells of Chironomus thummi larvae. III. The determination of the duration of the DNA synthesis period]. / Tsikl reduplikatsii DNK pri politenizatsii khromosom v kletkakh sliunnykh zhelez lichinok Chironomus thummi. III. Opredelenie prodolzhitel'nosti perioda sinteza DNK.

The duration of DNA synthesis in the salivary gland cells of Chironomus thummi larvae of the IV instar was determined by means of autoradiography and cytophotometry. Cells of different levels of ploidy differ in the duration of their DNA synthesis period. The tS of 2(10)c and 2(11)c cells was equal to 17 and 22 hours, respectively. The doubling of DNA content of the chironomid salivary gland cells leads to a 1.3 time increase in the duration of S-phase.

[Nonhomogeneity of the distribution of the absorbing substance in cytophotometry]. / Neravnomernost' respredeleniia pogloshchaiushchego veshchestva v tsitofotometrii.

Results of two-wavelengths cytophotometry may be used to calculate m--the quantity of light absorbing substance, and gamma--the degree of non-homogeneity of distribution of the substance on a preparation. Formula (1) is almost free from any distributional error. Optical density limits of applicability of formula (3) for gamma are shown on fig. 2. An algorithm for calculation of gamma at higher optical densities is proposed.

[Quantitative analysis of the DNA content in salivary gland chromosomes of Chrironomus thummi in the larval and prepupal stages]. / Kolichestvennyi analiz soderzhaniia DNK v khromosomakh sliunnykh zhelez Chironomus thummi na stadiiakh lichinki i predkukolki

Relative DNA content during the polytenization of the salivary gland nuclei of Chironomus thummi was measured by cytophotometric and cytofluorometric methods. To estimate polyteny degree, DNA content was calculated in hemocyte and spermatocyte nuclei. Chromosome polytenization is associated with the 10th-12th replication rounds. There are 4-5 replication rounds in the 1st instar, 2-3 rounds in the 2nd instar, the 3rd and the 4th instars have 1-2 rounds each. From early postembryonic development, larvae already have salivary gland nuclei representing two polyteny classes (2-2-2-4c), this heterogeneity being retained in all instars. Approximate DNA content is 0.51-0.58 picogram per a diploid set.

Quantitative analysis of DNA content in the salivary gland chromosomes of Chironomus thummi at larval and prepupal stages.

Relative DNA content during the polytenization of the salivary gland nuclei of Chironomus thummi was measured by cytophotometric and cytofluorometric methods. To estimate the degree of polyteny, the DNA content was calculated in hemocyte and spermatocyte nuclei. Chromosome polytenization is associated with 10 to 12 replication rounds. There are 4-5 replication rounds in 1st instar, 2-3 rounds in 2nd instar; 3rd and 4th instars have 1-2 rounds each. From early postembryonic development, larvae already have salivary gland nuclei representing two polyteny classes (2-3 - 2-4C); A similar heterogeneity is retained in all instars. The approximate DNA content is 0.51-0.58 picogram per diploid set.

[Characteristics of the endocrine system in Drosophila melanogaster 1 (2)gl mutants, differing in time of death]. / Kharakteristika éndokrinnoi sistemy u mutantov 1(2)gl Drosophila melanogaster, razlichaiushchiksia po vremeni gibeli

A comparative study of the state of the endocrine system and one of the larval organs, the salivary gland, has been carried out in larvae homozygous for the 1(2)gl gene. They differ in time of death (death at the third larval instar--larval allele, and at the prepupal state--prepupal allele). It is shown that homozygotes for the larval and prepupal allele have underdeveloped prothoracal glands. Corpora allata in homozygotes for the larval allele does not differ from the norm. Corpora allata in homozygotes for the prepupal allele is decreased proportionally to the decrease of prothoracal glands. A decrease of gland size is due to a decrease of the volume of cell but not to their number; this decrease is accompanied by the decrease of their relative DNA content. Salivary glands in homozygotes are reduced and comprise 80% of the normal size in homozygotes for the prepupal allele and 50% for homozygotes for the larval allele. Polyteny level in the salivary gland nuclei is much decreased as compared with the normal level. DNA level is more reduced in larvae homozygous for the larval allele.