Open AccessExpression of alpha-lactalbumin, alpha-S1-casein, and lactoferrin genes is heterogeneous in sheep and cattle mammary tissue.
Author(s) -
Adrian Molenaar,
Stephen R. Davis,
Richard J. Wilkins
Publication year - 1992
Publication title -
journal of histochemistry and cytochemistry/the journal of histochemistry and cytochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.971
H-Index - 124
eISSN - 1551-5044
pISSN - 0022-1554
DOI - 10.1177/40.5.1374090
Subject(s) - lactoferrin , mammary gland , lactation , alpha lactalbumin , biology , globules of fat , involution (esoterism) , casein , lactalbumin , alpha (finance) , medicine , endocrinology , gene expression , secretion , gene , milk fat , biochemistry , pregnancy , consciousness , genetics , construct validity , food science , nursing , cancer , neuroscience , breast cancer , patient satisfaction , linseed oil
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.