Electron microscopic and electron radioautographic study of cells in glandular hyperplasia and cancer of the endometrium

Peculiarities of the ultrastructure and RNA synthesis in the epithelial endometrial cells of nine patients with hyperplasia and the uterine cavity cancer have been studied by the electron-radioautographic method. Quantitative differences are revealed in the ultrastructures of the cells. Amplification of the nucleoli labelling and asynchronism of the RNA synthesis in the nucleoli with glandular hyperplasia and endometrial cancer are observed.     

Mobilization of the transposable element mdg4 by hybrid dysgenesis generates a family of unstable cut mutations in Drosophila melanogaster

Summary A family of unstable mutations at the cut locus in Drosophila melanogaster was obtained under the conditions of hybrid dysgenesis (Gerasimova 1981, 1982). The in situ hybridization experiments have shown that, in the original unstable ct ^MR2 mutation, the 7B region of the X chromosome (where cut is located) contains a mobile dispersed genetic element, mdg4. All other unstable ct mutations derived from ct ^MR2 including visible and lethal alleles and unstable ct ⁺ reversions, also contain mdg4 in the 7B region. The X chromosomes of the parent strain (wild type) do not contain mdg4 at all. All stable revertants derived from ct ^MR2, from other unstable ct mutations, or from ct lethals lost mdg4 from the 7B region. The ct ^MR2 X chromosome does not contain P-elements, although a few copies are present in the autosomes. The instability of the ct ^MR2./ct ^MR2 strain remained at a high level for 50 generations (1.5 years) and then rapidly decreased. A new cross with an MRh12/Cy strain (originally used for dysgenesis induction and containing a number of P-elements) increased the instability to a level exceeding the original one. The data strongly suggest that unstable ct mutations in our system are induced by transpositions of mdg4, possibly activated by P-elements.     

Superunstable alleles at the cut locus in Drosophila melanogaster

Summary This is a detailed study of the reversions of the ct ^MR2 allele putatively carrying á mobile element (MR-transposon) in the cut locus. Stable, unstable and superunstable revertants have been identified. Besides, a series of multiple unstable visible and lethal ct mutations derived from the ct ^MR2 allele have been obtained. They are shown to include supermutable alleles. The results suggest that the MR-transposon is connected with at least three functions: excision; change of orientation; and change of position within the cut locus, these functions being disturbed in different ways in different unstable ct ⁺ and ct alleles. In some cases the mutant transitions are somehow strongly stimulated leading to superinstability, reaching the rate of 0.5.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

Investigations on the organization of genetic loci in Drosophila melanogaster: lethal mutations affecting 6-phosphogluconate dehydrogenase and their suppression.

Summary The molecular nature of lethal and semilethal mutations in the Pgd locus of D. melanogaster coding for 6-phosphogluconate dehydrogenase (6PGD) was studied. All the 11 mutations affect the structural gene of the Pgd locus: 3 semilethal mutations resulted in altered 6PGD molecules with decreased catalytic activities; the rest 8 lethals were null alleles characterized by mutant polypeptides capable of reacting with antisera against highly purified 6PGD.Null or low activity alleles for glucose-6-phosphate dehydrogenase induced by ethyl methanesulfonate were shown to be suppressors for the lethal mutations in the Pgd locus.A monocistronic type of organization of the Pgd locus is suggested taking into account the biochemical mechanism of suppression of the Pgd-lethals and their location in the structural gene coding for 6PGD.     

Dominant Effects of Suppressor of Hairy-Wing Mutations on Gypsy-Induced Alleles of Forked and Cut in Drosophila Melanogaster

Mutations induced by the gypsy retrotransposon in the forked (f) and cut (ct) loci render their expression under the control of the suppressor of Hairy-wing [su(Hw)] gene. This action is usually recessive, but su(Hw) acts as a dominant on the alleles fk, ctk and ctMRpN30. Molecular analysis of the gypsy element present in fk indicates that this allele is caused by the insertion of a modified gypsy in which the region normally containing twelve copies of the octamer-like repeat that interacts with the su(Hw) product is altered. Analysis of the gypsy element responsible for the ctk and ctMRpN30 mutations also reveals a correlation between the dominant action of su(Hw) and disruption of the octamer region. We propose that these disruptions alter the affinity and interaction of su(Hw) protein with gypsy DNA, thereby sensitizing the mutant phenotype to fluctuations in su(Hw) product.