Reconstruction of Escherichia coli mrcA (PBP 1a) mutants lacking multiple combinations of penicillin binding proteins.

Previously, we constructed a set of mutants from which eight penicillin binding protein (PBP) genes were deleted in 192 combinations from Escherichia coli (S. A. Denome, P. K. Elf, T. A. Henderson, D. E. Nelson, and K. D. Young, J. Bacteriol. 181:3981-3993, 1999). Although these mutants were constructed correctly as determined by restriction mapping and the absence of relevant protein products, we recently discovered by PCR mapping that strains from which mrcA (PBP 1a) was deleted were also missing two neighboring genes of unknown function (yrfE and yrfF). We created a new deletion mutation in mrcA and reconstructed 63 strains lacking PBP 1a and other PBP mutant combinations. The new mrcA mutants do not exhibit mucoidy, phage resistance, temperature sensitivity, growth rate defects, or antibiotic resistance, suggesting that these phenotypes require the loss of either yrfE or yrfF alone or in combination with the absence of multiple PBPs.

Concentration of mRNA encoding 3 beta-hydroxysteroid dehydrogenase/delta 5,delta 4 isomerase (3 beta-HSD) and 3 beta-HSD enzyme activity following treatment of ewes with prostaglandin F2 alpha.

The objectives of these experiments were (1) to determine if prostaglandin F2 alpha (PGF2 alpha) decreased mRNA encoding 3 beta-hydroxysteroid dehydrogenase/d5,delta 4 isomerase (3 beta-HSD) specifically in large steroidogenic luteal cells, which contain the high affinity receptors for PGF2 alpha; and (2) to determine if the decreased concentration of mRNA encoding 3 beta-HSD following administration of PGF2 alpha was associated with a decrease in 3 beta-HSD enzyme activity. Ewes on days 11 or 12 of the estrous cycle were administered PGF2 alpha (25 mg i.v. followed by 10 mg i.m. 2 h later) and corpora lutea collected 4, 12, 24, or 48 h later (n = 4-5/time). Corpora lutea were also collected from non-injected (n = 4) or saline-injected (n = 4) control ewes. Administration of PGF2 decreased (P < 0.05) steady-state concentrations of mRNA encoding 3 beta-HSD to 35, 15, 9, and 5 percent of the concentrations in the control group at 4, 12, 24, and 48 h, respectively. Concentrations of mRNA encoding 3 beta-HSD in large luteal cells were decreased to 43% of controls 4 h following injection, which was similar to the decrease seen in steady-state concentrations of this mRNA in total luteal mRNA (35%). However, 3 beta-HSD enzyme activity was not significantly decreased by 48 h after PGF2 alpha injection. Thus, the dramatic decreased in mRNA encoding 3 beta-HSD was not associated with an immediate decrease in 3 beta-HSD enzyme activity and, therefore, does not appear to be responsible for the acute decrease in secretion of progesterone from ovine luteal tissue during PGF2 alpha-induced luteolysis.

Luteal expression of steroidogenic factor-1 mRNA during the estrous cycle and in response to luteotropic and luteolytic stimuli in ewes.

Steroidogenic factor-1 (SF-1) is a transcription factor involved in regulating basal and/or cAMP-induced increases in expression of several components of the steroidogenic pathway, including cytochrome P450 side-chain cleavage (P450scc), steroidogenic acute regulatory protein (StAR), and 3beta-hydroxysteroid dehydrogenase/delta5, delta4 isomerase (3beta-HSD). In experiment 1, on days 3, 6, 9, 12, and 15 of the estrous cycle, steady-state concentrations (fmol/microg poly A+ RNA) of SF-1 mRNA in luteal tissue were 0.09 +/- 0.01, 0.17 +/- 0.01, 0.24 +/- 0.03, 0.30 +/- 0.09, and 0.20 +/- 0.05, respectively (estrus = day 0; n = 4/d). Concentrations of SF-1 mRNA increased (p < 0.05) between days 3 and 12, but were not different among the other days of the estrous cycle. Luteal concentrations of SF-1 mRNA and concentrations of progesterone in sera were highly correlated (p < 0.01; r = 0.72). In experiment 2, ewes on days 11 or 12 of the estrous cycle were injected with 25 mg prostaglandin F2alpha (PGF2alpha) into the jugular vein followed by an injection of 10 mg PGF2alpha i.m. 2 h later. Corpora lutea were collected 4, 12, and 24 h after the first injection of PGF2alpha (n = 4-5 ewes/time). Control luteal tissue was collected from ewes on days 11-13 of the estrous cycle, which had not been injected (n = 4) or had been injected with saline 24 h previously (n = 4). Steady-state concentrations of SF-1 mRNA had decreased (p < 0.05) to 48% of control values by 4 h after injection, and remained low at 12 and 24 h. In experiment 3, ewes on days 9-12 of the estrous cycle were administered PGF2alpha (1 micromol), phorbol 12-myristate 13-acetate (PMA; 2 micromol), luteinizing hormone (LH; 20 microg), forskolin (50 microg), or vehicle (1 mL saline) directly into the ovarian artery. Corpora lutea were collected 0 (noninfused) 4, 12, or 24 h later (n = 3-4 animals/treatment/time) for quantification of SF-1 mRNA. Steady-state concentrations of mRNA encoding SF-1 were not affected by infusion of PGF2alpha or PMA, although concentrations of mRNA encoding StAR and 3beta-HSD were decreased (p < 0.05) by these treatments. Concentrations of mRNA encoding SF-1 were increased (p < 0.05) to 157 and 149% of control values by LH and forskolin, respectively, 12 h following infusion and returned to control values by 24 h following either treatment. In contrast, infusion of LH or forskolin did not change concentrations of mRNA encoding StAR, P450scc, or 3beta-HSD. In summary, during the estrous cycle, the pattern of expression of SF-1 mRNA was similar to the pattern of concentrations of progesterone in serum and expression of mRNA encoding P450scc, but differed from that previously shown for 3beta-HSD and StAR mRNA. The effects of administration of PGF2alpha on concentrations of SF-1 mRNA appeared to be dose-dependent. However, acute effects of PGF2alpha on mRNA encoding 3beta-HSD and StAR were observed when concentrations of mRNA encoding SF-1 were not influenced. In addition, although LH or forskolin increased luteal SF-1 mRNA 12 h following infusion, no increases in mRNA encoding StAR, P450scc, or 3beta-HSD were observed. Thus, during the midluteal phase of the estrous cycle, neither luteotropic nor luteolytic hormones appear to coordinately regulate mRNA encoding SF-1 and mRNA encoding StAR, P450scc, or 3beta-HSD.

Regulation of steady-state concentrations of messenger ribonucleic acid encoding prostaglandin F2 alpha receptor in ovine corpus luteum.

To investigate the regulation of ovine luteal receptors for prostaglandin F2 alpha (PGF2 alpha), reverse transcription-polymerase chain reaction was used to produce a 284-bp partial cDNA that was 98% identical to that reported for the bovine PGF2 alpha receptor (PGF2 alpha-R). In situ hybridization localized mRNA for PGF2 alpha-R specifically to large luteal cells. In experiment 1, pools of luteal tissue (n = 4/day) collected from ewes on Days 3, 6, 9, 12, and 15 of the estrous cycle were analyzed for mRNA encoding PGF2 alpha-R. There was no difference in mean steady-state concentrations of mRNA encoding PGF2 alpha-R among any of the days studied (range = 2.3 +/- 0.3 to 3.5 +/- 0.7 fmol PGF2 alpha-R mRNA/ microgram poly[A]+ RNA as assessed by slot-blot hybridization). In experiment 2, ewes on Day 11 or Day 12 of the estrous cycle were administered PGF2 alpha, and corpora lutea were collected 4, 12, or 24 h later (n = 4-5 per time point). Nontreated (n = 4) or saline-treated (n = 4) ewes served as controls. Luteal concentrations of mRNA encoding PGF2 alpha-R were decreased (p < 0.05) at 4, 12, and 24 h after injection of PGF2 alpha. In experiment 3, ewes (midluteal phase) were administered saline, PGF2 alpha, phorbol 12-myristate 13-acetate (PMA), or LH via ovarian arterial injection, and luteal tissue was collected 0, 4, 12, or 24 h later (n = 3-4 per treatment per time). Steady-state concentrations of mRNA encoding PGF2 alpha-R were decreased (p < 0.05) by PGF2 alpha and PMA treatment (4 and 12 h) but were increased (p < 0.05) at 24 h after LH treatment. In summary, 1) mRNA encoding PGF2 alpha-R was localized to large luteal cells; 2) concentrations of mRNA encoding PGF2 alpha-R did not vary during the estrous cycle; 3) treatment with PGF2 alpha or PMA to activate protein kinase C decreased concentrations of PGF2 alpha-R mRNA within 4 h of treatment; and 4) administration LH increased concentrations of mRNA encoding PGF2 alpha-R 24 h following injection.

Hormonal regulation of messenger ribonucleic acid encoding steroidogenic acute regulatory protein in ovine corpora lutea.

Steroidogenic acute regulatory protein (StAR), proposed to be involved in the transport of cholesterol to the inner mitochondrial membrane, has recently been cloned from MA-10 cells. Using reverse transcription-polymerase chain reaction, we generated a complementary DNA encoding 404 base pairs of StAR from ovine luteal tissue to perform studies regarding regulation of the messenger RNA (mRNA) encoding this protein. In Exp 1, ewes were hypophysectomized (HPX) on day 5 of the estrous cycle and administered saline or physiological regimens of LH and/or GH until collection of luteal tissue on day 12 of the estrous cycle (n = 4/group). Luteal concentrations [mean +/- SEM; femtomoles per microgram poly(A)+ RNA] of mRNA encoding StAR were lower (P < 0.05) in the HPX plus saline-treated ewes (26.4 +/- 7.3) than in day 12 pituitary-intact ewes (n = 4; 77.7 +/- 9.3). Replacement of LH (59.1 +/- 13.1), GH (59.1 +/- 12.8), or LH and GH (69.9 +/- 4.5) in HPX ewes increased (P < 0.05) concentrations of mRNA encoding StAR to values not different from those in day 12 controls. In Exp 2, ewes on day 11 or 12 of the estrous cycle were injected with prostaglandin F2 alpha (PGF2 alpha) to induce luteal regression. Corpora lutea were collected 4, 12, or 24 h after injection (n = 4-5/time point) and from untreated control ewes (n = 4) or 24 h after injection of saline (n = 4). Treatment with PGF2 alpha decreased (P < 0.05) concentrations of progesterone in serum 4, 12, and 24 h after injection. Concentrations of StAR mRNA were decreased (P < 0.01) to 47%, 19%, and 8% of control values 4, 12, and 24 h after PGF2 alpha injection, respectively. In Exp 3, ewes received ovarian arterial infusions of saline, PGF2 alpha, or phorbol 12-myristate 13-acetate (PMA), and luteal tissue was collected 0 (no infusion), 4, 12, or 24 h later (n = 3-4/group). Treatment with PGF2 alpha or PMA decreased (P < 0.05) concentrations of progesterone in serum 4, 12, and 24 h postinjection. Steady state concentrations of mRNA encoding StAR (P < 0.05) were 36% and 25% of the control value 12 and 24 h after PGF2 alpha injection. Injection of PMA decreased (P < 0.05) concentrations of StAR mRNA to 75% and 50% of control values at 4 and 12 h, but concentrations of mRNA encoding StAR were not different from control values at 24 h.(ABSTRACT TRUNCATED AT 400 WORDS)