Factors controlling phytoplankton primary productivity in Byram Lake,Mt. Kisco,N.Y., summer 1977

Phytoplankton productivity was measured in Byram Lake Reservoir during summer 1977. Depth integrated productivity (0–5 gC m^{– 2} d^–1) increased with station depth, which together with visibility measurements indicated that light did not limit deep station productivity (C1 and S2). Macrophytes at station C5 (shallow) reduced the euphotic zone to 0 in June.On a unit depth basis, C5 was the most productive station. Apparently changes in macrophyte growth, regulated by light and temperature, controlled phytoplankton production. At C1, productivity was related to levels of different nutrients at different depths, the thermocline influencing nutrient availability at mid-depth. At S2, NH₃-N controlled mid-depth productivity. Surface and mid-depth productivity appeared influenced by factors not measured in this study.     

Alcohol-induced changes in the phospholipid molecular species of Escherichia coli.

In Escherichia coli, the additon of ethanol resulted in the synthesis of an increased proportion of phospholipids containing two unsaturated fatty acids. The addition of hexanol resulted in the opposite effect, an increase in the proportion of monounsaturated molecular species. The alcohol-induced changes were quantitatively similar to those caused by changing growth temperature. These results suggest that both adaptation to temperature and alcohol-induced changes in lipid composition share some common regulatory features.     

Inheritance of enzymes and blood proteins in the leopard frog,Rana pipiens: Three linkage groups established

Individuals from natural populations of the leopard frog, Rana pipiens, were analyzed for electrophoretic differences in blood proteins and enzymes from an amputated digit. The proteins examined represent products of 72 loci. Presumptive heterozygotes at multiple loci were selected for experimental crosses. Mendelian inheritance of 18 protein variations were demonstrated in the offspring. Tests for linkage or independent assortment were performed for 75 locus pairs. Three linkage groups were established. Linkage group 1 contains two loci, aconitase-1 (Acon1) and serum albumin (Alb), with a 19% recombination frequency between them. Linkage group 2 contains four loci, glyoxalase (Gly), acid phosphatase-1 (Ap1), acid phosphatase-2 (AP2), and esterase-5 (Est5). The data show the relationships Gly-21.1%-AP1-0%-AP2-6.3%-Est5, and Gly-25.6%-Est5. Linkage group 3 consists of four closely linked esterase loci. The data, Est1-5.1%-Est6, Est6-1.8%-Est10-1.9%-Est4 and Est6-3.0%-Est4, do not establish a complete order but suggest that Est10 is between Est4 and Est6. These results, with data demonstrating apparent independent assortment of 67 other locus pairs, provide a foundation for establishing the frog genetic map.The project was supported by Grant No. RR-00572 from the Division of Research Resources, National Institutes of Health. This paper is contribution No. C-87 from the Amphibian Facility, George W. Nace, Director.     

Inhibition of unsaturated fatty acid synthesis in escherichia coli by the antibiotic cerulenin.

Low concentrations of cerulenin inhibit the growth of Escherichia coli by selectively blocking unsaturated fatty acid synthesis. This inhibition was relieved by unsaturated fatty acid supplements alone but not by saturated fatty acid supplements. The utilization of exogenous unsaturated fatty acids to sustain growth in the presence of cerulenin was confirmed by the analysis of bulk lipid composition. The effects of cerulenin on fatty acid synthesis were examined in vivo by pulse labeling with [14C]acetate and in vitro using [14C]malonyl-coenzyme A. In both cases, unsaturated fatty acid synthesis was inhibited by low concentrations of cerulenin with a stimulation of saturated fatty acid synthesis. Using mutant strains deficient in fatty acid synthesis, the effects of cerulenin on beta-ketoacyl-[acyl-carrier-protein] synthetases I and II were examined. Our results indicate that beta-ketoacyl-[acyl-carrier-protein] synthetase I is more sensitive to inhibition by cerulenin than beta-ketoacyl-[acyl-carrier-protein] synthetase II.     

Low-temperature conditional cell division mutants of Escherichia coli.

Fifteen low-temperature conditional division mutants of Escherichia coli K-12 was isolated. They grew normally at 39 degrees C but formed filaments at 30 degrees C. All exhibited a coordinated burst of cell division when the filaments were shifted to the permissive temperature (39 degrees C). None of the various agents that stimulate cell division in other mutant systems (salt, sucrose, ethanol, and chloramphenicol) was very effective in restoring colony-forming ability at 25 degrees C or in stimulating cell division in broth. One of these mutants, strain JS10, was found to have an altered cell envelope as evidenced by increased sensitivity to deoxycholate and antibiotics, as well as leakage of ribonulcease I, a periplasmic enzyme. This mutant had normal rates of DNA synthesis, RNA synthesis, and phospholipid synthesis at both the nonpermissive and permissive temperatures. However, strain JS10 required new protein synthesis in the apparent absence of new RNA synthesis for division of filaments at the permissive temperature. The division of lesion in strain JS10 is cotransducible with malA, aroB, and glpD and maps within min 72 to 75 on the E. coli chromosome.     

The immune response of brown trout (Salmo trutta L.) to injection with soluble antigens.

The immune response of brown trout (Salmo trutta) to horse serum and keyhole limpet haemocyanin was studied. Intraperitoneal and intramuscular injections were used, with and without adjuvant, in 209 fish. Complement-fixing antibodies (CFA) and precipitins were produced to both antigens. CFA were detected after 8 days to haemocyanin and after 13 days to horse serum. Maximum CFA titres to a single intraperitoneal injection of horse serum or haemocyanin were reached at 44 and 43-46 days respectively. Precipitins to a single injection of haemocyanin given intraperitoneally were detected after 19 days using gel diffusion. Similarly using the intramuscular route they were detected after 22 days. However, using counter-current electrophoresis, precipitins were detected after 8 days by the intraperitoneal route and after 9 days by the intramuscular. Precipitins to horse serum given intraperitoneally were demonstrated after 22 days by both gel diffusion and counter-current electrophoresis. Fish given 2 intraperitoneal injections of haemocyanin in adjuvant reached maximum CFA titres after 55 days; a 3rd injection on day 56 did not produce a marked increase in titre. Fish given intramuscular injections of haemocyanin in adjuvant showed maximum CFA titres at day 43. After a 3rd injection on day 56, maximum CFA titres were reached between days 92 and 106. Intramuscular injections gave significantly higher titres than those given by the intraperitoneal route. Some fish which showed no precipitins by gel diffusion were positive by counter-current electrophoresis. Precipitating antibodies to haemocyanin migrating in the beta2-gamma1 region were detected by immuno-electrophoresis.     

Structural studies on the O-specific side-chains of the cell-wall lipopolysaccharide from Escherichia coli O 75

The structure of the O-specific side-chains of the cell-wall lipopolysaccharide of Escherichia coli O 75 has been investigated, using methylation analysis and Smith degradation as the principal methods. The O-specific side-chain was found to be composed of a tetrasaccharide repeating-unit of the following structure:

     

Globin synthesis in fibroblasts fused with erythroblasts. I. Avian fibroblasts.

Heterokaryons of chick embryo erythroblasts fused with other avian fibroblasts were studied with regard to globin production. After the incorporation of radioactive amino acids, soluble proteins were separated on SDS-urea polyacrylamide gels. There was a striking increase in radioactivity above background in the globin region from lysates of fusion cultures when compared with fibroblast cultures. This was maximal at 24 hours after fusion, and then declined. Electrophoresis on acid-or alkaline-urea gels further identified the material as globin chains. Tryptic digestion and fingerprinting revealed methionine-labeled peptides characteristic of chick embryo erythroblast globin. An apparent stimulation of globin chain synthesis by heterokaryons compared to erythroblasts was found to be due to a difference in the specific activity of the precursor amino acid pools in the different cell types.     

Vaginal microbiome-hormonal contraceptive interactions associate with the mucosal proteome and HIV acquisition

Alterations to the mucosal environment of the female genital tract, such as genital inflammation, have been associated with increased HIV acquisition in women. As the microbiome and hormonal contraceptives can affect vaginal mucosal immunity, we hypothesized these components may interact in the context of HIV susceptibility. Using previously published microbiome data from 685 women in the CAPRISA-004 trial, we compared relative risk of HIV acquisition in this cohort who were using injectable depot medroxyprogesterone acetate (DMPA), norethisterone enanthate (NET-EN), and combined oral contraceptives (COC). In women who were Lactobacillus-dominant, HIV acquisition was 3-fold higher in women using DMPA relative to women using NET-EN or COC (OR: 3.27; 95% CI: 1.24–11.24, P = 0.0305). This was not observed in non-Lactobacillus-dominant women (OR: 0.95, 95% CI: 0.44–2.15, P = 0.895) (interaction P = 0.0686). Higher serum MPA levels associated with increased molecular pathways of inflammation in the vaginal mucosal fluid of Lactobacillus-dominant women, but no differences were seen in non-Lactobacillus dominant women. This study provides data suggesting an interaction between the microbiome, hormonal contraceptives, and HIV susceptibility.