Short communication: Mouse mammary tumor virus driven α-lactalbumin expression effects on lactation and fertility of transgenic mice.

α-Lactalbumin (Alac) is one of the major milk proteins. Its gene expression is restricted to epithelial cells of the lactating mammary gland. The Alac interaction with a uridine 5'-diphosphate-galactosyltransferase induces lactose synthesis, a major osmotic regulator of milk secretion. Other functions attributed to this protein include induction of apoptosis and anti-inflammatory activities. To assess if forced expression of this gene during early gestation or involution could affect mammary physiology, an Alac-encoding minigene was expressed in transgenic mice under the transcriptional regulation of the mouse mammary tumor virus promoter. The mammary expression did not interfere with gestation, resulted in a slight increase in milk yield as indirectly assessed by the 11% increased growth rate of the pups reared by transgenic females compared with that of those reared by control mice, and induced a slight delay in the early involution process, as demonstrated by histological analyses. The use of the mouse mammary tumor virus promoter resulted in Alac expression in several nonmammary tissues, such as the brain, the testis, the ovary, and the uterus. Although it did not affect male reproductive performances, it induced a female subfertile phenotype, characterized by embryonic implantation failure in the transgenic female reproductive tract.

Goat PRND expression pattern suggests its involvement in early sex differentiation.

Expression of the goat prion protein gene locus was assessed by reverse transcriptase-polymerase chain reaction on testes and ovaries at various developmental stages. A weak and stochastic expression of the PRNP and PRNT genes was observed. For PRNT, it is consistent with the detected deletions of two single nucleotides within its open reading frame in ruminant genes. PRND was expressed in both tissues at all stages. Whereas its expression is constant in the ovaries, it increases in testes between 36 and 46 days postcoitum (dpc) and remains high thereafter. In testes, Doppel was found in the nucleus of germinal cells and in the cytoplasm of Leydig cells at 44 dpc. It was detected in the cytoplasm of Leydig cells and of some Sertoli and germinal cells at 62 dpc. In the ovaries, it was observed in the nucleus of germinal cells at 44 dpc and mainly in their cytoplasm at 62 dpc. This expression pattern was shown to parallel that of C-kit and suggests Doppel involvement in early testis differentiation.

Rat prolactin synthesis by lactating mammary epithelial cells.

It has previously been suggested that the mammary cell could produce prolactin (PRL). This hypothesis was investigated by incubation with [35S]methionine-cysteine followed by SDS-PAGE, immunoblotting and autoradiography of immunoprecipitated PRL, and by electron microscopic analysis after incubation without or with cycloheximide. Immunoreactive 14-, 23-, 25-, 32- and 36-kDa PRL forms were radioactive. By two-dimensional electrophoresis analysis, immunoreactive and radioactive spots, of about 25 kDa and high molecular weight, were also detected. After incubation of mammary epithelial cells with cycloheximide, immunogold electron microscopy showed a drastic decrease of labelling in organelles involved in synthesis and secretion, compared to those incubated in control medium. These results make it possible to conclude that lactating mammary tissue is able to synthesize PRL.

Characterization of the goat lactoferrin cDNA: assignment of the relevant locus to bovine U12 synteny group.

Lactoferrin (LTF), which is the major iron-binding protein in milk and physiological fluids, belongs to the transferrin family. We report here the sequence of a caprine LTF cDNA, 2411 bp in length, encoding the pre-protein (709 amino acid residues). Sequence comparisons reveal that structural features, including iron-binding sites, cysteine residues involved in disulphide bonds are remarkably conserved between LTF proteins from various species. Of the 5 potential glycosylation sites identified, only one site appears to be conserved between artiodactyls, rodents and humans. Using a somatic cell hybrid panel, the LTF locus was assigned to the bovine U12 syntenic group. This assignment and the localization of the LTF gene on bovine chromosome 22 (BTA 22) by Schwerin et al. (1) using fluorescent in situ hybridization achieves an additional analogy between a synteny group and a chromosome in cattle. Since serum transferrin (STF) had been previously mapped on BTA 1, in cattle LTF and STF loci are not localized on the same chromosome, conversely to the situation observed in humans (HSA 3) and mice (MMU 9).

[Use of progestagens in subcutaneous implants for the control of sexual cycles in the cow]. / Utilisation de progestagènes en implants sous-cutanés pour la maîtrise des cycles sexuels chez les bovins

PIP: Estrus synchronization and related fertility were studied in cattle using subcutaneous implants containing norethandrolone, SC 21009, or fluorogestone acetate. Lengthening the duration of treatment decreases the rate of estrus inhibition. For long-term (16-18 days) treatments, the percentage of cows showing estrus with 4 days from implant removal increases with the initial content of the implant; 61.5% and 84.6% with 6 and 12 mg SC21009 respectively. The progestagen content of the implant has little effect on fertility, but longer duration of treatment lowers fertility: 49.4% and 27.3% for 10 and 16 days, respectively, for SC 21009 implants. Fluorogestone acetate had little effect. Estradiol valerate injection at the time of implant insertion increases fertility regardless of treatment duration. The use of high-potency progestagens permits the use of small implants. Cross-link percentage must be studied for each progestagen. Of the progestagens studied, only SC 21009 is sufficiently potent for implant use.^ieng