Frequency of lethal chromosomal and genome mutations in man

According to the cytogenetic studies chromosome anomalies frequency in 209 children who died in the perinatal period was 7.2 per cent. These cases were found to consist of 8 autosome trisomies, 5 anomalies in sex chromosome system, 1 case of triploidy and 1 case of structural reorganization. Accounting for the elimination of chromosome anomalies during the early periods of fetus development, the frequency of chromosome lethals was shown to be 6.44 X 10(-2) in registered pregnancies and 54.89 X 10-2 in conceptions.     

Interactions of Abscisic Acid, Cytokinin and Gibberellin in the Control of Betacyanin Synthesis in Seedlings of Amaranthus caudatus

In de-rooted seedlings of Amaranthus caudatus L., betacyanin synthesis induced by white light or cytokinin was inhibited by abscisic acid (ABA) or a mixture of gibberellins A₄ and A₇ (GA_4/7). The GA_4/7 and ABA effects were additive. Thus ABA inhibited the cytokinin action but had no effect on the gibberellin response.     

Action of heparin on protein fractions of isolated nuclei and on their DNA content.

Isolated nuclei of rat hepatocytes were incubated with 0.05% sodium heparinate for 2 to 10 min. Alterations in the nuclei were controlled biochemically, determining the amounts of DNA and histones, and by cytophotometric methods determining the amounts of total and nonhistone proteins and DNA. Under the selected experimental conditions 95% of histones are bound already after 5-min incubation with heparin; nonhistone proteins of cell nuclei remain unchanged. The blockade of histones is followed by DNA diffusion into the incubation medium. Experiments with nuclear staining with alcian blue proved the specificity of heparin binding with histones and showed that heparin-histone complex remains in the nuclei, and its histones lose their extractability with 0.25 n HCl.     

Heterologous transformation in Bacillus subtilis. 1. Transmission of DNA of the R1drd19 plasmid]

Bac. subtilis 168 (BD-25) cells were infected with DNA of plasmide R1drd19 isolated from E. coli strain; transformants resistant to streptomycin (500 microgram/ml) and kanamycin (40 microgram/ml) appeared with the frequency of 2.10(-6). These transformants retained resistance to the mentioned antibiotics stably. A satellite DNA peak was revealed in centrifugation in the density gradient of cesium chloride with ethidium bromide. It was possible to infect cells of Bac. subtilis 168 (BD-25) with plasmide DNA isolated from the transformants. Plasmide transduction with the aid of phages AR9 and PBSI multiplied on the transformant strains was also effected. Physico-chemical analysis of the transformed plasmide DNA was conducted; its molecular weight was determined.     

Investigation of the mechanism of protein turnover in HeLa S-3 cells by incubation at elevated temperatures

An apparent paradox relating to the degradation of endogenous proteins in HeLa S-3 cells occurs at 45 degrees C, at which their proteolysis is considerably enhanced in vitro but completely inhibited in vivo. No significant differences in rates of degradation of short-lived (nascent) and long-lived ('existing') proteins synthesised at 37 degrees C were found when chased at temperatures up to 43 degrees C, but at 45 degrees C degradation of both categories was reduced to zero in vivo. Synthesis of protein was suppressed at temperatures above 41 degrees C, being reduced by up to 60% at 43 degrees C. Proteolysis in vitro proceeded 1.6-1.7 times faster at 45 degrees C than at 37 degrees C and neutral pH. Evidence is presented for the involvement of the basal system; the findings both in vivo and in vitro do not seem to implicate the lysosomal system, no firm indication being obtained of its 'induction' at elevated temperatures. The results are discussed in terms of the arrest of intracellular circulation at elevated temperatures, thereby reducing the delivery rate of proteins as substrates of the intracellular basal proteolytic enzyme system to negligible levels (i.e., to the frequency of encounters due solely to the diffusion of protein molecules with the cytoplasm).