Effects of twice-weekly follicular punctures of ovaries with or without the corpus luteum on follicular and luteal dynamics.

We investigated the effects of twice-weekly follicular punctures of ovaries with or without corpus luteum (CL) on follicular and luteal dynamics. A cross-over design was used, with each cow (seven Japanese Black beef cows) being assigned to one of the three groups at 2-month intervals. Follicular punctures were performed twice weekly for three consecutive weeks until day 20 (oestrus = day 0). All visible follicles (diameter >3 mm) in the ovaries bearing CL (ipsilateral group) or those in the contralateral ovaries (contralateral group) were aspirated. As a control, all visible follicles in both ovaries were aspirated (bilateral group). Follicular development, CL formation and progesterone concentrations in each cow were monitored from days 0 to 30. Follicular growth profiles in the punctured ovaries during/after puncture treatment were similar, irrespective of the presence of follicles in the unpunctured ovary and the CL in the punctured or unpunctured ovaries. After puncture, two cows (28.6%) each in the ipsilateral and bilateral groups did not exhibit behavioural oestrus until day 30, whereas all cows in the contralateral group exhibited oestrus. CL growth and increase in progesterone concentrations after the last follicular puncture in the bilateral group were delayed when compared with those in the ipsilateral group. Our results indicate that the presence of follicles in the unpunctured ovary and the CL in the punctured or unpunctured ovaries does not significantly influence follicular growth in punctured ovaries during/after puncture treatment. However, follicular puncture in ovaries bearing CL may disturb or delay oestrus occurrence after treatment.

Localization of estradiol-responsive region in the phenobarbital-responsive enhancer module of mouse Cyp2b-10 gene.

The mouse Cyp2b-10 gene is inducible by treatment with estradiol as well as so-called phenobarbital (PB)-like inducers. To identify 5'-flanking elements responsible for induction by estradiol, we carried out reporter gene assays using a primary mouse hepatocyte culture system. Cyp2b-10 gene-driven luciferase activities were induced by estradiol as well as PB in this system. Deletion analysis demonstrated that the sequence contained within the region from -2331 bp to -2281 bp was responsible for the estradiol-induced luciferase activity. This region corresponds to the core element of PB-responsive enhancer module (PBREM). Several nucleotide mutations in the putative binding sites of the PBREM core element showed that the NR1 site was required for estradiol induction, and the same element was required for PB induction. These results indicate that estradiol induces Cyp2b-10 gene expression via PBREM.

Biological properties of a plaque-inducing agent obtained from Acholeplasma oculi.

A plaque-forming agent arose spontaneously during cloning of Acholeplasma oculi 19L. The agent produced plaques on A. oculi 19L and A. oculi-i, but not on A. laidlawii, A. modicum, or wild isolates of A. oculi. The agent required horse serum for plaque formation as well as for adsorption to the indicator lawn; however, it was extremely sensitive to an inhibitor in some horse sera. The agent retained infectivity after passage through a 50 nm filter and was heat-, Nonidet P-40-, and chloroform-labile, but relatively ether-stable. It was not determined whether the agent is a virus or a bacteriocin-like substance.

The components of Mycoplasma salivarium and its growth medium that are responsible for film formation.

Studies on film production by mycoplasmas revealed that film was produced by completely disintegrated mycoplasma cells on Noble agar in the presence of horse serum. Film production was due to an enzymic reaction between mycoplasma lipase, possibly phospholipase A, and phospholipid in serum.