Involvement of the galactosyl-1-phosphate transferase encoded by the Salmonella enterica rfbP gene in O-antigen subunit processing.

rfbT of Salmonella enterica LT2 was previously thought, together with rfaL, to be involved in the ligation of polymerized O antigen to core-lipid A, and three mutants were known. We report the mapping of the mutations to rfbP, the galactosyl-1-phosphate transferase gene, which is now shown to encode a bifunctional protein. The mutations which have the former rfbT phenotype are referred to as rfbP(T). We also show that rfbP(T) mutants are not blocked in the ligation step as previously believed but in an earlier step, possibly in flipping the O-antigen subunit on undecaprenyl pyrophosphate from the cytoplasmic to periplasmic face of the cytoplasmic membrane.     

Indomethacin inhibition of ovulation in the cow

Indomethacin or saline was administered via intramuscular, intrauterine or intraovarian routes to dairy cows, within 24 h after standing oestrus was first observed. The incidence of ovulation was determined at slaughter. All of the saline-treated cows (18/18) ovulated. Ovulation was not blocked after intramuscular injection (0/6) or intrauterine infusion (0/6) of indomethacin. In all cows, ovulation was blocked after intraovarian injection (6/6) of indomethacin. These findings add support to the hypothesis that prostaglandins play an essential role in ovulation in the cow as in many other mammalian species.     

In vivo phosphorylation of isocitrate lyase inEscherichia coli andAcinetobacter calcoaceticus

Isocitrate lyase inEscherichia coli and inAcinetobacter calcoaceticus is phosphorylated when the cells are grown with acetate as the sole carbon source in low-phosphate mineral salts medium containing³²P inorganic phosphate. The level of³²P incorporation into the enzyme in both microorganisms appears to be constant throughout the entire growth cycle. Further, theresults of immunoblots and rocket immunoelectrophoresis suggest that the amount of isocitrate lyase protein, although at different levels in each microorganism, also remains constant throughout the growth cycle.     

Cloning and nucleotide sequence of the Salmonella typhimurium LT2 gnd gene and its homology with the corresponding sequence of Escherichia coli K12

Summary The complete nucleotide sequence of the Salmonella strain LT2 gnd gene for 6-phosphogluconate dehydrogenase was determined. The gene contains 1404 bases and encodes a 468 amino acid polypeptide, which is the same as for Escherichia coli K12. The DNA sequence shows 14.8% difference between the two and the amino acid sequence 3.6% difference. Changes are mostly in the third codon base and most of the amino acid changes are conservative.     

Use of a synthetic dodecapeptide (malantide) to measure the cyclic AMP-dependent protein kinase activity ratio in a variety of tissues.

1. The cyclic AMP-dependent protein kinase activity-ratio assay was investigated by comparing histone and a synthetic peptide, malantide [Malencik & Anderson (1983) Anal. Biochem. 132, 32-40], as substrates. 2. In several tissues the activity ratio was higher when assayed with histone as the substrate; this result was obtained in control tissues and also in those incubated with agents known to increase cyclic AMP. The effect of these agents to increase the activity ratio was more clearly demonstrated with malantide. 3. The higher activity ratios observed with histone are due to: (a) measurement of phosphorylation not catalysed by cyclic AMP-dependent protein kinase; (b) activation of cyclic AMP-dependent protein kinase by histone during the assay. 4. When tissues were homogenized in buffers without NACl, lower activity ratios were found, owing to the catalytic subunit being artifactually removed from the supernatant. 5. We conclude that the measured activity ratio more faithfully reflects that in the tissue when NaCl is included in the homogenization buffer and malantide is used in the assay. This was confirmed in experiments where cyclic AMP-dependent protein kinase was added to the tissue before homogenization, and no dissociation of the exogenous enzyme was observed.     

Quantity and quality of embryos collected from mice passively immunized against estradiol

The objective of this study was to determine the effects of passive immunization against estradiol on the occurrence and timing of estrus, ovulation and fertilization rates and on early embryonic development in mice. Swiss Webster fermale mice were randomly assigned to one of the three treatment groups to be injected with 0.1 ml saline (control; n=15), 0.1 ml anti-estradiol antisera (high dose: n=17) or 0.1 ml antiestradiol antisera diluted 1:10 with saline (low dose; n=17) at seven weeks of age. Immediately after injection mice were placed with males and observed daily for the presence of vaginal plugs for 10 d. Three days after vaginal plugs were observed, mice were terminated and the uteri were removed and flushed to determine the number and quality of unfertilized ova and embryos. No differences were observed in the timing of vaginal plug formation, the proportion of mice with vaginal plugs, or the mean number of unfertilized ova or embryos collected from each treatment group. However, the proportion of excellent or good quality embryos was reduced in the high dosage treatment. It was concluded from this study that passive immunization of mice against estradiol did not increase the number of embryos obtained from mice and that a high dosage of antisera against estradiol reduced embryo quality. These results provide evidence that alterations in levels of estradiol may adversely affect embryonic development.