Diastereoisomers of cyclocymopol and cyclocymopol monomethyl ether from Cymopolia barbata

Optically active diastercoisomers of the brominated monoterpene quinols, cyclocymopol and cyclocymopol monomethyl ether, were isolated from the green marine alga Cymopolia barbata and charac- terized.     

High Numbers of Prosthecate Bacteria in Pulp Mill Waste Aeration Lagoons

Prosthecate bacteria comprised 0.6 to 10.5% of the bacterial community in samples from 11 pulp mill waste aeration lagoons. Because of their distinct morphology, the genera Ancalomicrobium, Caulobacter, Prosthecobacter, Prosthecomicrobium, Stella, and Hyphomicrobium or Hyphomonas could be identified and enumerated by direct microscopic examination. Monthly samples from one lagoon showed that several genera varied from undetectable to predominant among the appendaged organisms. Temperature (season), type of wood pulped, and pulping process did not significantly affect the density of prosthecate bacteria.     

Schistosoma mansoni: Cytotoxicity of hemocytes from susceptible snail hosts for sporocysts in plasma from resistant Biomphalaria glabrata

Sporocysts of Schistosoma mansoni (PR1 strain) survive and grow in Biomphalaria glabrata PR albino strain snails, whereas they are encapsulated and die in B. glabrata 10R2 strain snails. These processes also occur in an in vitro system in which the only living cells are those of sporocysts and snail hemolymph. Hemocytes of the susceptible snail are normally not effective in damaging sporocysts. However, when the encounter occurred in the presence of cell-free plasma from resistant snails, previously impotent hemocytes severely damaged sporocysts in 24 hr. The cytotoxic capacity of resistant strain hemocytes was not altered by plasma from susceptible snails. Furthermore, it was retained even when plasma was replaced by culture medium free of snail components. The nature of the plasma factor(s) which facilitated damage by otherwise impotent hemocytes is discussed, and evidence is evaluated for the hypothesis that snail resistance is dependent upon the specificity of cytophilic factors present both in the plasma and on the hemocyte plasma membranes.     

Alcohol dehydrogenase-coupled spectrophotometric assay of epoxide hydratase activity

A coupled assay was devised for the assay of liver microsomal epoxide hydratase using the ability of alcohol dehydrogenase to transfer electrons from diols to NAD⁺: epoxide hydratase activity was continuously monitored at 340 nm. Rates of hydrolysis of octene-1,2-oxide and styrene-7,8-oxide measured utilizing this assay were similar to those determined using gas-liquid chromatography and radiometric thin-layer chromatography, respectively. The assay was used to examine the ability of rat liver microsomes and highly purified rat liver microsomal epoxide hydratase fractions to hydrolyze 15 other epoxides.     

Numerical relationship between cells with radiation-induced chromosome aberrations and cells lethally injured by radiation

Summary The numerical relationship between radiation-induced chromosome aberrations in humanG ₀ lymphocytes and reproductive lethality of human bone-marrow lymphocytes is analysed within a large LET interval. The comparison is based upon the evaluation of the coefficient of the linear component of the corresponding dose-effect-relation for the frequency of cells without aberrations and for the frequency of surviving cells respectively. The good correlation between these coefficients over a large LET interval supports the hypothesis that structural chromosome aberrations and reproductive cell death both result from the same gross chromatin damage.This work was supported by the Bundesministerium des Innern, Bonn     

Outer membrane protein a and other polypeptides regulate capsular polysaccharide synthesis in E. coli K-12.

Summary capR (lon) mutants of Escherichia coli K-12 are mucoid on minimal agar because they produce large quantities of capsular polysaccharide. When such mutants are transformed to tetracycline resistance by plasmid pMC44, a hybrid plasmid that contains a 2 megadalton (Mdal) endonuclease EcoR1 fragment of E. coli K-12 DNA joined to the cloning vehicle-pSC101, capsular polysaccharide synthesis is inhibited and the transformed colonies exhibit a nonmucoid phenotype. Re-cloning of the 2 Mdal EcoR1 fragment onto plasmid pHA105, a min-colE1 plasmid, yielded plasmid pFM100 which also inhibited capsular polysaccharide synthesis in the capR mutants. A comparison of the polypeptides specified by both plasmids pFM100 and pMC44 in minicells demonstrated that seven polypeptide bands were specified by the 2 Mdal DNA, one of which was previously demonstrated to be outer membrane protein a; also known as 3b or M2 (40 kilodaltons, Kdal). Plasmid mutants no longer repressing capsular polysaccharide synthesis were either unable to specify the 40 K dal outer membrane protein a or were deficient in synthesis of 25 K dal and 14.5 K dal polypeptides specified by the 2 Mdal DNA fragment. Studies with a minicell-producing strain that also contained a capR mutation indicated that the capR gene product regulated processing of at least one normal protein, the precursor of outer membrane protein a.     

Inhibition of dihydropteridine reductase by dopamine

Dihydropteridine reductase has been purified 900-fold from rat liver. Dopamine inhibited the enzyme up to 50% at a concentration of 0.11mm. In the presence of dopamine the enzyme gave non-hyperbolic v-against-[S] plots. This enzyme may have a role in control of dopamine biosynthesis.     

CORRECTION OF THE NAME PSEUDOTETRAÉDRON POLYMORPHUM (CHLOROPHYCEAE)1

A unicellular chlorococcalean alga, Pseudotetraëdron polymorphum MacEntee, Bold & Archibald is renamed Chlorotetratëdron polymorphum (MacEntee, Bold & Archibald) MacEntee, Bold & Archibald became the former generic designation has been preempted by a xanthophycean alga.     

Relationship of F9 antigen and genes of theT/t complex

Serological studies relating F9 antigen of embryonal carcinoma cells to at the murineT/t complex have been extended and confirm that only the lethal haplotype t¹²- and none of the other five lethal haplotypes-affects the quantitative expression of F9 antigen on sperm. Cytotoxicity tests on preimplantation embryos show that t¹² homozygotes are less susceptible to antiF9 serum than t^w5 homozygotes, and that using specific antimutant haplotype antisera prepared against sperm, t¹² antigen is detectable on morulae, whereas t^w5 antigen is not.