Relationship of formate to growth and methanogenesis by Methanococcus thermolithotrophicus

Methanococcus thermolithotrophicus is a methanogenic archaebacterium that can use either H2 or formate as its source of electrons for reduction of CO2 to methane. Growth and suspended-whole-cell experiments show that H2 plus CO2 methanogenesis was constitutive, while formate methanogenesis required adaptation time; selenium was necessary for formate utilization. Cells grown on formate had 20 to 100 times higher methanogenesis rates on formate than cells grown on H2-CO2 and transferred into formate medium. Enzyme assays with crude extracts and with F420 or methyl viologen as the electron acceptor revealed that hydrogenase was constitutive, while formate dehydrogenase was regulated. Cells grown on formate had 10 to 70 times higher formate dehydrogenase activity than cells grown on H2-CO2 with Se present in the medium; when no Se was added to H2-CO2 cultures, even lower activities were observed. Adaptation to and growth on formate were pH dependent, with an optimal pH for both about one pH unit above that optimal for H2-CO2 (pH 5.8 to 6.5). When cells were grown on H2-CO2 in the presence of formate, formate (greater than or equal to 50 mM) inhibited both growth and methanogenesis at pH 5.8 to 6.2, but not at pH greater than 6.6. Both acetate and propionate produced similar inhibition. Formate inhibition was also observed in Methanospirillum hungatei.     

Investigation of mercaptans,organic sulfides,and inorganic sulfur compounds as sulfur sources for the growth of methanogenic bacteria

A variety of compounds were investigated for use as sulfur sources for the growth of methanogenic bacteria.Methanococcus (Mc.) deltae, Mc. maripaludis, Methanobacterium (Mb.) speciesGC-2B, GC-3B, andMMY, Methanobrevibacter (Mbr.) ruminantium, andMethanosarcina (Ms.) barkeri strain 227 grew well with sulfide, S^o, thiosulfate, or cysteine as sole sulfur source.Mbr. ruminatium was able to grow on SO ₄ ⁼ or SO ₃ ⁼ , andMs. barkeri strain 227 was able to grow on SO ₃ ⁼ , but not on SO ₄ ⁼ as a sole sulfur source.Mc. jannaschii grew with sulfide, S^o, thiosulfate or SO ₃ ⁼ , but not on cysteine or SO ₄ ⁼ as sole surface source.Mc. thermolithotrophicus, Mc. jannaschii, Mc. deltae, andMb. thermoautotrophicum strains Marburg and H were able to grow with methanethiol, ethanethiol,n-propanethiol,n-butanethiol, methyl sulfide, dimethyl sulfoxide, ethyl sulfide, or CS₂ as a sulfur source, when very low levels (20–30 M) of sulfide were present; no growth occurred on 5–100 M sulfide alone. Methanethiol, ethanethiol, and methyl sulfide-using cultures produced sulfide during growth.     

Patterns of cancer in geographic and endogamous subdivisions of the Hutterite Brethren of Canada

The Hutterite Brethren comprise a religious isolate and live on communal agricultural farms (colonies) in North America. In 1976 there were approximately 15,000 Canadian Brethren living in 179 colonies of the three endogamous subdivisions, the Dariusleut, Lehrerleut, and Schmiedeleut. Dariusleut and Lehrerleut colonies are located in both Alberta and Saskatchewan, and the Schmiedeleut are in Manitoba. Brethren were identified on population-based cancer registries of the three Prairie Provinces and among death registrations in the vital statistics of Alberta and Saskatchewan. The method of ascertainment was by a search for the 15 contemporary surnames and verification by address. 89 male and 91 female Brethren were identified who had cancer during the period, 1956--1975. The numbers of observed cancers were less than expected from provincial incidence rates for males and females in each province. The largest deficits were for female Brethren in Manitoba and Saskatchewan. There is a marked deficiency of cancer of the uterine cervix among female Brethren. In males there is a significant deficit of lung cancer. The Hutterite way of life contributes to a low risk for cancers of smoking-associated sites. However, there is evidence that male Brethren in Alberta may be at relatively increased risk for stomach cancer and leukemias. The site distribution patterns of cancers among the three endogamous leut are similar.     

Purification and characterization of human mitochondrial creatine kinase. A single enzyme form

Purification of human mitochondrial creatine kinase has been difficult and procedures that were highly successful in purifying canine enzyme failed for human mitochondrial creatine kinase. In the present study, we employed ultracentrifugation to remove the lipid, urea to prevent aggregation, followed by a final step of chromatofocusing which yielded a preparation of human mitochondrial creatine kinase with a specific enzyme activity of greater than 400 IU/mg. Biochemical and immunological characterization showed the preparation to be highly pure and free of even trace amounts of other creatine kinase isoenzymes. Antiserum specific for mitochondrial creatine kinase was developed which exhibited no cross-reactivity to cytosolic creatine kinase and mitochondrial creatine kinase did not cross-react with antiserum to the cytosolic forms. Marked differences were noted, both biochemically and immunologically, between mitochondrial creatine kinase and the cytosolic forms. Human mitochondrial creatine kinase was shown to have a molecular weight of around 82,000 and to be composed of two subunits of equal molecular weights around 41,000. Aggregates of mitochondrial creatine kinase were observed with molecular weights of around 200,000 in the absence of urea or if isolated from material after having undergone proteolysis. Isolation from fresh material or in the presence of urea inhibited aggregate formation for both canine and human mitochondrial creatine kinase. Despite claims of several investigators that mitochondrial creatine kinase exhibits two to three forms with varying molecular weights, our data indicate a single enzyme form made up of a subunit with a molecular weight of 41,000 and the high molecular weight aggregates appear to be induced artifacts. A radioimmunoassay was developed for human mitochondrial creatine kinase which, with appropriate modifications, should detect mitochondrial creatine kinase in human plasma.     

Serum Albumin Washing Specifically Enhances Arachidonate Incorporation into Synaptosomal Phosphatidylinositols

Arachidonate incorporation into synaptosomal phospholipids was shown to be affected by factors including the procedure for preparation of the membrane fractions and preincubation of synaptosomes prior to assay of incorporation of arachidonate into both phosphatidylcholine (PC) and phosphatidylinositol (PI). However, the inhibition toward incorporation into PIs, but not PCs, was fully reversed when the membranes were washed with bovine serum albumin. A twofold increase in arachidonate incorporation into PIs was also observed when freshly prepared synaptosomes were washed with serum albumin immediately before assay of incorporation activity. The inhibitory action is thought to be due to an increase in polyunsaturated fatty acids and/or their oxidation products which may then elicit a special effect on the acyltransferase responsible for transferring arachidonate into phosphatidylinositols. The differences in fatty acid uptake and response to serum albumin also suggest the presence of different acyltransferase for acyl transfer to PIs and PCs.     

Detergent Effects on the Phosphatidylinositol-Specific Phospholipase C in Rat Brain Synaptosomes

In the presence of Ca2+ (2.5 mM) and using [14C]arachidonoyl phosphatidylinositol (PI) membrane as substrate, phosphatidylinositol-specific phospholipase C (PI-PLC) (EC 3.1.4.10) in rat brain synaptosomes was activated by deoxycholate but not taurocholate. Calcium stimulated enzymic hydrolysis by both detergents, but the stimulatory effect of taurocholate was less than that of deoxycholate. Peak stimulation for deoxycholate was observed at 1 mg/ml, whereas that for taurocholate was 4 mg/ml. When 1 mM EDTA was added to the taurocholate (4 mg/ml) and Ca2+ (3.5 mM) system, synaptosomal PI-PLC activity was greatly stimulated, to almost the same level as the deoxycholate + Ca2+ system. This system required the presence of all three factors, and EGTA could not effectively replace EDTA in the stimulatory action. The detergent-induced hydrolysis of synaptosomal PI by the deoxycholate + Ca2+ and the taurocholate + Ca2+ + EDTA systems was strongly inhibited by divalent metal ions such as Zn2+, Cu2+, Pb2+, and Fe2+, whereas Mg2+ and Ca2+ were ineffective. Nevertheless, only the deoxycholate + Ca2+ system was responsive to enzyme inhibition by membrane-perturbing agents such as lysophospholipids and free fatty acids. The specific requirement for EDTA in the taurocholate system may be due to the release of a pool of inhibitory divalent metal ions from the membranes.     

Rapid Test for Urease and Phenylalanine Deaminase Production

A rapid urea-phenylalanine medium was effective for the identification of Proteus and, with one exception, Providencia. Most Klebsiella and a few Enterobacter were urease-positive with this method.     

A combination rapid and standard method for identification of Candida albicans

A medium consisting of an aqueous extract of zein, lactose, and Tween 80 is used together with an overlay of 1 % Tween 80 and coverslipping to provide a combined rapid (germ tube) and standard (chlamydospore) method for diagnosis ofCandida albicans. The method is exquisitely sensitive for diagnosis ofC. albicans but lumps chlamydospore-producing strains ofC. tropicalis withC. albicans.