Effect of Streptococcus faecalis BIO-4R on intestinal flora of weanling piglets and calves.

The effect of oral administration of Streptococcus faecalis BIO-4R, an antibiotic-resistant lactic acid bacterium, on the intestinal flora of weanling piglets and cows reared on antibiotic-containing diet was investigated. Fourteen days after administration of the bacteria, the intestinal flora of the piglets was examined. Animals of the administered group had stabilized lactic flora such as bifidobacteria, streptococci, and lactobacilli, whereas most animals of control group had reduced lactic flora. On the other hand, abundant yeasts were detected from the cecum, colon, and feces of the control animals, but the levels were significantly lower in the animals given strain BIO-4R. The density of Salmonella in the intestine appeared to be reduced after the administration of strain BIO-4R. The number of BIO-4R cells was shown to be 10 times lower in the duodenum and jejunum than in the ileum, suggesting that strain BIO-4R might have grown transiently in the ileum. The similar trend toward stabilization of the lactic flora was also observed in cows after administration of BIO-4R. In addition, an antagonistic effect of the strain against yeasts and Salmonella was suggested. These findings indicate that the oral administration of strain BIO-4R is one of the useful methods whereby the potentially deleterious effect of antibiotics on the intestinal flora of farm animals may be minimized.     

Formation of Chlorophyll-Protein Complexes in Greening Cucumber Cotyledons in Light and then in Darkness

The changes in chlorophyll-protein complexes (CPs) in cucumbercotyledons during illumination and subsequent dark incubationwere studied by SDS-polyacrylamide gel electrophoresis. Whenetiolated cucumber seedlings were illuminated, chlorophyll wassynthesized and CPs were formed. In the early phase of greening(6 h of illumination), light-harvesting chlorophyll a/b-proteincomplex (LHCP) was the main GP. As the greening proceeded, P700chlorophyll a-protein complex (CP1) accumulated. When 6-h illuminatedseedlings were transferred to darkness, CP1 accumulated concomitantlywith a decrease in LHCP without new chlorophyll synthesis. Thechanges in the amounts of CPs in the dark became smaller withthe progress of greening and were not observed after 72 h ofillumination. These changes were confirmed by examining thechlorophyll/P700 ratio and the low temperature absorption spectrumof cotyledons. These results suggest that in the early phaseof greening, CPs were unstable and their chlorophyll moleculeseasily exchanged with those of other kinds of CPs. (Received October 14, 1982; Accepted December 1, 1982)     

Isolation and Purification of Cytochrome b561 from a Photosynthetic Bacterium, Rhodopseudomonas sphaeroides

Cytochrome b₅₆₁ was removed from chromatophores of a photoanaerobicallygrown Rhodopseudomonas sphaeroides by deoxycholate-cholate andTriton X-100 treatments of the chromatophores. The cytochromewas purified by ammonium sulfate fractionation and gel filtration.Its molecular weight was 45,000 (45 kD) and it was composedof three subunits with molecular weights of 23 kD, 19 kD andless than 6 kD. The cytochrome preparation had absorption maximaat 414 nm in the oxidized form, and at 428, 530 and 561 nm inthe reduced form. Its pi was 4.8. The midpoint potential ofthis cytochrome was 153 mV at pH 7.0. The compound was autooxidizable,and it had cytochrome c oxidase activity. (Received May 16, 1983; Accepted September 8, 1983)     

A temperature-sensitive mutant of E. coli exhibiting slow processing of exported proteins

A temperature-sensitive E. coli mutant with a mutation in the spc ribosomal protein operon was found to have a conditional defect in the processing of precursor proteins destined for the periplasmic space or the outer membrane. At high temperatures, significant amounts of precursor proteins having unprocessed signal sequences are detected in the mutant cell by pulse-labeling. The precursors are processed at very slow rates during a subsequent chase. Genetic analysis indicates that the mutation impairs the function of a gene, termed secY, located at the promoter-distal part of the spc operon. The secY gene is distinct from those genes previously known to specify ribosomal proteins, yet it is within the spc operon. It is suggested that the product of the secY gene is a component of the cellular apparatus that is essential for protein secretion across the cytoplasmic membrane. The gene secY is probably identical with prlA, previously identified as a suppressor of signal sequence mutations.     

Role and induction of 2,3-bisphosphoglycerate synthase

Molecular and Cellular Biochemistry - 2,3-Bisphosphoglycerate accumulates in mammalian erythrocytes, where it facilitates the supply of oxygen to the tissues by binding to hemoglobin. Regulatory...     

Inhibition of Thiamine Pyrophosphate Utilization by Thiamine or Its Monophosphate in Escherichia coli

The growth of a thiamine pyrophosphate auxotroph of Escherichi coli was inhibited by either thiamine or thiamine monophosphate, and the growth of a thiamine monophosphate auxotroph was inhibited by thiamine. The thiamine pyrophosphate-dependent oxidation of pyruvate was inhibited by thiamine with whole cells of the thiamine pyrophosphate auxotroph but not with cell extracts prepared from the same organism. In addition, the thiamine pyrophosphate uptake of the thiamine pyrophosphate auxotroph was inhibited by either thiamine or thiamine monophosphate. Although the thiamine pyrophosphate uptake of a revertant, selected for prototrophy from the thiamine monophosphate auxotroph, was inhibited by thiamine to an extent comparable to that observed with the thiamine monophosphate auxotroph, its growth was no longer inhibited by thiamine. A possible mechanism for the inhibition by thiamine and thiamine monophosphate in the utilization of thiamine pyrophosphate is discussed.     

Adenine-dependent growth of marine yeast,Rhodotorula glutinis var.salinaria under sodium chloride-hypertonic condition

Nitrate and ammonium were shown to alter the growth ofRhodotorula glutinis var.salinaria in saline and non-saline media. In saline medium in which ammonium was the sole nitrogen source, ammonium inhibited growth in the presence of molybdate ions. Detailed comparisons of the growth in saline and non-saline media when nitrate was supplemented in the presence of molybdate ions showed that differences in utilizability of purine bases of nucleic acid were responsible for the differences in growth,i.e. adenine increased the growth in such saline medium, but decreased it in non-saline medium. There was not such a specific requirement for adenine in saline medium in the presence of molybdate ions when nitrate was substituted for ammonium as the sole nitrogen source. It was suggested that adenine might provide the necessary skeleton of nucleic acid for serving nitrate reduction in saline medium.