Quantitative characteristics of radiation injury of the spermatogenic epithelium and the rate of its recovery after exposure to fast neutrons and gamma-radiation

The paper submits the results of studies on the kinetics of spermatogenous epithelium cell number after exposure to fast neutrons (60-300 cGy) and gamma-radiation (200-600 cGy). It was shown that a relative decrease in the quantity of spermatocytes is determined by an exponential dose-response curve with D0 of 35 and 120 cGy for neutrons and gamma-radiation respectively. For spermatides and spermatozoa a single D0 value of 20 and 55 cGy was obtained for neutrons and gamma-radiation respectively. As the radiation dose increases the recovery process in the epithelium is substantially decelerated. The equation T1/2 = T1/2(0)e0.0009D well describes the dependence of the half-recovery period T1/2 upon the equivalent dose.     

Isolation and partial characterization of EGF-like growth factor from rat glioma tissue

Using acid-ethanol extraction, two proteins with Mr=8 and 12 kD were extracted from rat glioma tissue induced with ethylnitrosourea. These proteins were shown to complete for the receptor with [125I]EGF (epidermal growth factor) on A431 cells. The 8 kD protein exhibited a marked mitogenic effect by stimulating DNA synthesis in resting NIH 3T3 cells. Stepwise chromatography of the acid-ethanol extract on Biogels P-60 and P-10 resulted in preparative amounts of the protein and allowed for its partial characterization. It was found that the half-maximum stimulation of DNA synthesis in NIH 3T3 cells was achieved at growth factor protein concentration of 5 micrograms/ml. The preparation obtained possessed the EGF-competing activity of 10 ng-equiv. EGF per 1 microgram of protein and stimulated protein phosphorylation of the 170 kD protein in NRK cell membranes. The data obtained suggest that this factor may be related to the family of the so-called EGF-like growth factors.     

The Influence of Changes in Magnetic Variations and Light–Dark Cycle on Life-History Traits of Daphnia magna

Day–night cycle is the main zeitgeber (time giver) for biological circadian rhythms. Recently, it was suggested that natural diurnal geomagnetic variation may also be utilized by organisms for the synchronization of these rhythms. In this study, life-history traits in Daphnia magna were evaluated after short-term and multigenerational exposure to 16 h day/8 h night cycle, 32 h day/16 h night cycle, diurnal geomagnetic variation of 24 h, simulated magnetic variation of 48 h, and combinations of these conditions. With short-term exposure, the lighting mode substantially influenced the brood to brood period and the lifespan in daphnids. The brood to brood period, brood size, and body length of crustaceans similarly depended on the lighting mode during the multigenerational exposure. At the same time, an interaction of lighting mode and magnetic variations affected to a lesser extent brood to brood period, brood size, and newborn's body length. The influence of simulated diurnal variation on life-history traits in daphnids appeared distinctly as effects of synchronization between periods of lighting mode and magnetic variations during the multigenerational exposure. Newborn's body length significantly depended on the lighting regime when the periods of both studied zeitgebers were unsynchronized, or on the interaction of light regime with magnetic variations when the periods were synchronized. These results confirm the hypothesis that diurnal geomagnetic variation is an additional zeitgeber for biological circadian rhythms. Possible mechanisms for these observed effects are discussed. Bioelectromagnetics. © 2020 Bioelectromagnetics Society     

A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7–Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target. Cells of either innate immunity (neutrophils and monocytes) or acquired immunity (CD4⁺ and CD8⁺ lymphocytes) can produce this complex, which confirms the close connection between components of the 2 branches of immune response.     

Interaction of histone H1 from sea urchin sperm with superhelical and relaxed DNA

Complexes of histone H1 from sea urchin sperm (H1S) and calf thymus (H1T) with superhelical DNA I and relaxed circular DNA II have been analyzed by analytical sedimentation. Similar to H1T, the highly basic and relatively arginine-rich histone H1S preferentially interacts with DNA I compared to DNA II under competition conditions. However, H1S induces a stronger aggregation of bothforms of DNA than H1T. Below 0.05 M NaCl, the soluble complexes formed by both histones have similar properties, but aggregation proceeds in a different manner: H1S induces a stronger aggregation of DNA II as compared to DNA I, whereas H1T fails to aggregate DNA I.The results are explained on the basis of differences in amino acid sequence and structure of the two histones and related to the special chromatin condensing ability of histone H1S.     

Structure of the chromatin with long linker DNA

The method of velocity sedimentation have been used to investigate ionic-strength-induced compaction of sea urchin sperm chromatin characterized by extremely long linker DNA (100 b.p.). The dependence of sedimentation coefficients of oligonucleosomes on the number of nucleosomes in the chain have been studied in the range of ionic strength from 0.005 to 0.085. Analysis of these data indicates that such structural parameters of sea urchin sperm chromatin fibre as the diameter of the chain and the length of the chain per nucleosome are quite similar to those of chromatin with shorter linker DNA, but the DNA packing ratio is higher. The structure of sea urchin sperm oligonucleosomes agrees well with the model of three-dimensional zig-zag-shaped chain with linker DNA forming a loop. The possible role of alpha-helical regions of the C-terminal domain of sea urchin sperm histone H1 in the long linker DNA folding is discussed.     

Genetic structure of an isolated group of the indigenous population of northern Siberia--Nganasans (Tavgiitsi) of Taymyr. I. History, erythrocyte and serum blood systems, isoenzymes]

Nganasans is a small samodyen-speaking ethnic group originated from several clans of reindeer hunters. Pedigree studies revealed no consanguineous matings of uncle-niece, aunt-nephew, first cousins type among 120 families studied. Rather rarely mating between second cousins could be observed. The reviewed traditional kindship system based on bilateral exogamy is an explanation. Data on 12 blood systems and 6 red cell enzymes distribution in two main localities almost totally studied have been presented. No A2, r, K, MS alleles were observed. Hgh frequencies of Ns, R2, Fya, Jka, Gm1 have been found. Diegoa was seen in only one family. Polymorphism on PGM1, 6-PGD, AK and AP, monomorphism on LDH and MDH has been observed.     

Proliferation of the intestinal epithelium and of the regenerating liver with a deficiency of the epidermal growth factor

To determine the role of the epidermal growth factor (EGF) in the regenerative stimulation of intestinal epithelium and hepatocyte proliferation after partial resection of these organs the labeling index of the intestine and liver in sialadenectomized rats was studied. EGF concentration in the saliva and serum was determined using radioimmunoassay. The decrease in EGF concentration after the removal of submandibular salivary glands was shown to slower hepatocytes entering the mitotic cycle and to inhibit the activity of enterocyte proliferation in the small intestine. The data show pronounced in vivo mitogenic effect of EGF on the liver and intestinal epithelium.     

On the role of gene of SER-4 serotonin receptor in thermotolerance of Caenorhabditis elegans behavior

Serotonin reduces the behavior tolerance of Caenorhabditis elegans of the N2 wild-type strain (swimming induced by the mechanical stimulus) to a temperature of 36°C. The sensitivity to the serotonin influence on the behavior thermotolerance remains intact in strains with null mutations of mod-1(ok103) and ser-1(ok345) serotonin receptor genes, and is almost completely lost in the ser-4(ok512) strain with null mutation in the gene of the SER-4 serotonin receptor, which is a homologue of 5-HT₁ mammalian serotonin receptor. In addition, nematodes of the ser-4(ok512) strain have high behavior thermotolerance in the absence of the exogenous serotonin compared to the N2 strain. These data indicate the involvement of the ser-4 gene in the serotonin regulation of the tolerance of C. elegance nervous system functions to hyperthermia.