Journal of Histochemistry and Cytochemistry, Vol. 50, 257-264, February 2002, Copyright © 2002, The Histochemical Society, Inc.
Immunochemical Demonstration of
s1- and ß-Casein in Mouse Mammary Glands at Early Stages of Pregnancy
Takuya Kanazawaa and
Kaoru Kohmotoa
a Department of Animal Breeding, Faculty of Agriculture, University of Tokyo, Tokyo, Japan
Correspondence to:
Takuya Kanazawa, College of Agriculture, Ibaraki University, Ami-machi, Ibaraki 300-0393, Japan. E-mail: takuyak@msv.ipc.ibaraki.ac.jp
We generated monoclonal antibodies (MAbs) against mouse
s1- and ß-casein and used them to survey casein immunochemically in mammary glands of mice at peri-coitous and pregnant stages. Two MAb-producing hybridoma cells, designated MC
1 cell and MCß1 cell, were established. Each antibody, when used in Western blotting, recognized specifically mouse
s1- and ß-casein among a wide spectrum of proteins of both a lactating mammary homogenate and mouse skim milk. Immunohistochemistry revealed
s1- and ß-casein in sections of lactating mammary glands. Staining was found in substances in the lumen and cytoplasm of duct and alveolar cells, particularly in rough endoplasmic reticulum and the Golgi apparatus. Mammary glands at Days 2, 4, 6, 8, and 14 of pregnancy showed positive staining specific to both
s1- and ß-casein in the lumen and cytoplasm of duct cells, whereas the glands at estrus and Day 0 of pregnancy were positive mainly for
s1-casein. Semiquantitative Western blotting analysis of both casein components in epithelial cell fractions from glands during pregnancy confirmed that intra-epithelial
s1- and ß-casein changed during three phases, elevated from trace levels to detectable levels during initial stages of pregnancy (Days 0, 2, and 4), declined to lower levels during mid-pregnancy (Days 6 and 8), and then rose to high levels during late pregnancy (Day 14).
(J Histochem Cytochem 50:257264, 2002)
Key Words:
mouse
s1-casein, mouse ß-casein, monoclonal antibody, immunohistochemistry, mouse mammary gland