We used 35S-labeled cRNA probes to localize the sites of alpha-lactalbumin, alpha-S1-casein, and lactoferrin mRNA synthesis in sheep and forcibly weaned cattle mammary tissue. Expression of alpha-lactalbumin was absent in three of four "virgin" glands studied, present in some alveoli of "pregnant" glands but not in others, despite a similar histological appearance. In the early lactating gland, expression was high in those alveoli with few fat globules in their cells and lumen and was absent in alveoli with abundant fat globules. These observations suggest either that alpha-lactalbumin gene expression is linked to the long-term secretory activity of cells and falls once cells are resting or regressing, or that there are cyclical variations in expression, or that in the lactating gland some groups of epithelial cells are synthesizing alpha-lactalbumin and some are synthesizing fat. Expression patterns of alpha-S1-casein were similar to those of alpha-lactalbumin. Lactoferrin, in contrast, was expressed almost exclusively in the "fatty alveoli" of both species. Our results show that dramatic variations in milk gene expression can occur throughout the mammary gland of sheep and cattle and that at no stage of pregnancy, lactation, or involution can the gland be considered metabolically homogeneous.
Previous in situ hybridisation studies from our laboratory have shown that expression of certain milk protein genes is very high in some areas of the mammary glands of sheep and cattle, while in other areas containing an abundance of fat globules, it is virtually zero. We wished to determine if this heterogeneity was due to local variations in the concentrations of lactogenic hormones andlor their receptors. Artificially increasing the local concentration of lactogenic hormones in the sheep udder was attempted by inserting time release capsules containing prolactin, hydrocortisone and insulin directly into the gland up to one week before sacrifice. The local concentration of prolactin, and the milk gene expression relative to controls, appeared unchanged by the implants. The immunoreactivity of prolactin and its receptor in the mammary epithelial cell cytoplasm and in particular, the nuclei, were demonstrated and appeared to vary with the secretory activity of the ‘cell.
Summary Pasture bloat is a serious economic and animal welfare problem in cattle grazed on legumes in New Zealand. Analysis of salivary proteins from dairy cattle in herds bred for either low or high susceptibility to bloat has resulted in the identification of a 30 kilodalton protein, which we term bSP30, whose relative abundance is negatively correlated with bloat score (r = ‐0.40 ± 0.12). From 74 animals sampled, relative abundance of bSP30 was 66 ± 15% higher in the low‐susceptibility herd than in the high‐susceptibility herd. Relative abundance of bSP30 also varied significantly within individuals, according to feeding or time of day, and from day to day, A sequence homology search of 38 amino acids derived from three tryptic fragments of the protein suggests that the amino acid sequence of bSP30 has not been described previously. Amino acid analysis indicates that bSP30 is not a member of the proline‐rich family of salivary proteins. The function of bSP30 is unknown but it is conceivable that it plays a role in the aetiology of bloat.
We report here the separation of chromosomal DNA molecules from the diplokl pathogenic yeast C. albicans by field inversion gel electrophoresls (FIOEK1).Our earlier work on C. albicans ATCC strain 10261 revealed a pulsed field gel electrophoretic pattern of six bands, two of which were possibly doublets (2).In the present study we found that FIGE gave superior resolution with uniform DNA mobility between lanes, and therefore could be used to examine the possibility of electrophoretic karyotype variation in this asexual yeast The extension of our study to other strains of C. albicans showed that local clinical isolates, strain 22114 (from MX).Richardson, Birmingham, England) and our ATCC 10261 reference strain exhibit considerable differences in rheir FIGE banding patterns (Figure).However, certain similarities are apparent, especially in bands 3 and 6.Probing Southern blols with C. albicans DNA probes which complement the HIS3, ADE2 and URA3 genes in S. cerevisiae gave results supporting this conclusion.ri(^» f Tnminntirm nf (h> vpripnt rfimmnntnw, irvjnrllng fmthf-r probing, snggfaited that they may have had common origins, but have undergone rearrangements which involve either one or both bomotogues of a diploid pair.However, we do not believe £hat C. albicans chromosomes are overly unstable, since ATCC 10261 strains freeze-dried in 1960 and 196S gave the same banding pattern as an ATCC 10261 strain in laboratory culture for the last IS years.Thus, FIGE electrophoretic patterns could be a valuable means of characterising and identifying C. albicans strains.The molecular basis of these chromosomal variations and their pbenotypic and medical consequences are of obvious interest Finally, we recommend the use of type strains for the rational genetic analysis of C. albicans.Figure: Yeast chromosomal DNA molecules resolved by FIGE.Lanes a-e are C. albicans (e 22114; b: 1346/6; c: W4112; d: 255/6; e: ATCC 10261), lane f is Saccharomyces cerevisiae 2180 (truncated pattern).Running conditions were 160 V, 22 hrs, 1% agarose, 7°C with ramp switching times over the run of forward 10->60i and backward 3->20s.DNA wu prepared and bands are numbered according toRef.2.
Pituitary PRL regulates seasonal hair follicle growth cycles in many mammals. Here we present the first evidence implicating PRL in the nonseasonal, wave-like pelage replacement of laboratory mice. In this study we show that messenger RNA transcripts encoding the one long and two short forms of PRL receptor are present in the skin of adult and neonate mice. The receptor protein was immunolocalized to the hair follicle as well as the epidermis and sebaceous glands. Furthermore, PRL messenger RNA was detected within skin extracts, suggesting a possible autocrine/paracrine role. Analysis of the hair growth phenotype of PRL gene-disrupted mice (PRLR(-/-)) revealed a change in the timing of hair cycling events. Although no hair follicle development differences were noted in PRLR(-/-) neonates, observations of the second generation of hair growth revealed PRLR(-/-) mice molted earlier than wild types (PRLR(+/+)). The advance was greater in females (29 days) than in males (4 days), resulting in the elimination of the sexual dimorphism associated with murine hair replacement. Heterozygotes were intermediate between PRLR(-/-) and PRLR(+/+) mice in molt onset. Once initiated, the pattern and progression of the molt across the body were similar in all genotypes. Although all fiber types were present and appeared structurally normal, PRLR(-/-) mice had slightly longer and coarser hair than wild types. These findings demonstrate that PRL has an inhibitory effect on murine hair cycle events. The pituitary PRL regulation of hair follicle cycles observed in seasonally responsive mammals may be a result of pituitary PRL interacting with a local regulatory mechanism.
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