Mammary-derived growth inhibitor protein and messenger ribonucleic acid concentrations in different physiological states of the gland.
Expression of mammary-derived growth inhibitor in tissue from lactating and involuting bovine mammary glands was investigated. Seventeen lactating, pregnant (220 to 272 d in gestation) cows were divided in two groups of 8 and 9 cows each. Cows of the first group were slaughtered while in lactation. Cows of the second group (9 involuting cows) were slaughtered at 13 to 52 d following sudden cessation of milking. High concentrations of mammary-derived growth inhibitor (.63% of the total protein) were detected in mammary tissue of lactating cows. Mammary-derived growth inhibitor (less than .10% of the total protein) was dramatically reduced during most of the involution period (13 to 45 d following cessation of milking). Mammary-derived growth inhibitor was again detected (.28% of the total protein) during the last stage of the involution (46 to 53 d after cessation of milking), which coincided with colostrum formation. When steady state concentrations of mammary-derived growth inhibitor mRNA were examined, the results obtained mirrored those obtained at the protein concentration. These data suggest that regulation of mammary-derived growth inhibitor occurs via modulation of the steady state concentration of its mRNA. Furthermore, there is a strong correlation between mammary-derived growth inhibitor expression and lactation in dairy cows.
Politis
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Department of Animal Science, Cornell University, Ithaca 14853.
Gorewit
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Muller
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Grosse
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D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D004797:Enzyme-Linked Immunosorbent Assay; D050556:Fatty Acid-Binding Proteins; D005260:Female; D006131:Growth Inhibitors / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D007774:Lactation / Q000378:metabolism* / Q000502:physiology; D008321:Mammary Glands, Animal / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D010452:Peptide Biosynthesis; D010455:Peptides / Q000032:analysis / Q000235:genetics; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis
D002352:Carrier Proteins; D050556:Fatty Acid-Binding Proteins; D006131:Growth Inhibitors; D010455:Peptides; D012333:RNA, Messenger