Recombinant haplotype H-2 in mice of the congenic resistant strain B10.D1(R108)/Y

Recombinant H-2 haplotype of mouse strain B10.D1(R108)/Y (symbol R108) obtained in experiments with skin grafting in the course of developing the CR B10.D1/Y strain (strain DBA/LacY--the donor of H-2q) was studied. Strains with recombinant H-2 haplotypes a, h2, g1, i3, i5, i7, m, y1 were used. Alleles of different H-2 (K, I, D) regions were determined according to the presence or absence of genetic complementation in the F1 test with skin grafts. R108 recombinant was studied by serological methods with panel of anti-H-2 sera. Anti-H-2Kb (H-2.33) and anti-H-2Dq (H-2.30) monospecific antisera were used in microcytotoxicity test and in absorption experiments in vitro. It was concluded that crossing over between H-2b and H-2q chromosomes, which led to formation of recombinant H-2 haplotype of R108 mice, occurred at I region, between IA and IC subregions. The H-2 complex of R108 line has KbIAbIJ?IE?ICqSqDq alleles. bq1 symbol was proposed for the H-2 haplotype of B10.D1(R108)/Y strain.     

Dominant mutations of rifampicin resistance in Escherichia coli K-12

Significant portion (up to 20%) of dominant mutations (rifd mutations) was observed among spontaneous mutations of rifampicin resistance picked up in cells of haploid Escherichia coli strain. These mutations are similar to rifd mutations obtained earlier when selecting them in rif-s/rif-s merodiploids. On the basis of analysis of nucleotide substitutions taking place in formation of spontaneous and induced mutations, it is established that rifd mutations are caused by single nucleotide substitution. The majority of rifd mutations are localized in a small region of the central part of RNA polymerase beta-subunit gene covering less than 200 base pairs. A rifd mutant has been described which occurred as a result of micro-deletion in one of the "hot" spots of the central region of beta-subunit gene.     

Oxygen demand and long term changes of profundal zoobenthos

The paper attempts to combine the low oxygen content of the hypolimnion during stratification and the oxygen uptake of zoobenthos. Data of declining oxygen content in the hypolimnion and critical limits of respiration are combined for Chironomus anthracinus, Potamothrix hammoniensis and three species of Pisidium, P. casertanum, P. subtruncatum and P. henslowanum. The respiratory adaptation to low oxygen content influences both growth and population dynamics of the different species. The results have important bearing on eutrophication of the Lake Esrom ecosystem and temperate eutrophic lakes in general as well as the composition of profundal zoobenthos and its population dynamics.Publication No. 389 from Freshwater-Biological Laboratory, University of Copenhagen.     

The use of different oils for the cultivation ofStreptomyces cinnamonensis

The addition of 2–4% oils to the synthetic fermentation medium used for the cultivation ofStreptomyces cinnamonensis increased the production of monensin three times on the average. When the amount of the added oil was lower than 2% and higher than 4% the production sharply decreased. The maximal production preceded the maximal consumption of individual fatty acids of the added oils, the content of oleic acid decreasing most pronouncedly.     

The effect of glucose on cellobiose uptake and β-D-glucosidase activity inStreptomyces granaticolor

Glucose inhibits the inducible synthesis of β-D-glucosidase inStreptomyces granaticolor. Neither cAMP nor cGMP influence the inhibitory effect of glucose. Glucose also inhibits the inducible synthesis of the cellobiose uptake system but has no effect on its activity. This may be the mechanism underlying glucose inhibition of induction of β-D-glucosidase inS.granaticolor.     

Effect of domestic sewage on sand beach meiofauna at Goa,India

Meiofauna of a sewage-polluted sandy beach, where sand alone constituted > 90%, was surveyed. Nematodes dominated the fauna numerically at all stations, followed by harpacticoid copepods. Most of the animals were confined to the top 5 cm of the sediment. A seasonal pattern was observed in the distribution of the fauna. There were significant spatial and temporal variations in mean meiofauna density, attributed to organic discharge via sewage and prevailing environmental conditions in the study area.     

Inhibition by prolactin of gonadotrophin-induced cyclic AMP accumulation in the preovulatory ovary

We investigated whether prolactin acts at the ovarian level by interfering with the accumulation of gonadotrophin-induced ovarian cyclic AMP. Mouse ovaries were incubated with hCG and varying doses of prolactin. At the end of the incubation, the cyclic AMP which accumulated in the tissue + medium was measured. In ovaries devoid of corpora lutea, a significant inverse correlation (r = -0.93, P less than 0.05) was obtained between the doses of prolactin (0.1-25.6 micrograms ovine prolactin) and hCG-induced accumulation of ovarian cyclic AMP. In the presence of the phosphodiesterase inhibitor IBMX, however, the same doses of prolactin failed to exhibit any restricting influence on the accumulation of cyclic AMP. In luteinized ovaries, the same doses of prolactin in the absence of IBMX did not inhibit the hCG-induced cyclic AMP accumulation.     

Isolation and characterization of human placenta fibronectin

Fibronectin was isolated from human placenta tissues and compared with human plasma fibronectin. Placenta and plasma fibronectins had similar amino acid compositions, immunological properties, and cell attachment-promoting activities, but differed in apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which could be accounted for at least partly by the difference in carbohydrate composition. Unlike plasma fibronectin, placenta fibronectin failed to form a precipitin line with concanavalin A in a double diffusion system. The non- or low-reactivity of placenta fibronectin with this lectin was also demonstrated by affinity chromatography with concanavalin A-agarose, in which more than 90% of the radiolabeled glycopeptides derived from placenta fibronectin was not retained on the gel. The two fibronectins also differed in the reactivity with Lens culinaris agglutinin of their glycopeptide fractions. These data indicate that placenta and plasma fibronectins are different in their carbohydrate structures and, therefore, suggest the presence of a tissue- or cell-specific mechanism for processing the carbohydrates of this glycoprotein.