Rabbit Whey Acidic Protein Concentration in Milk, Serum, Mammary Gland Extract, and Culture Medium

Abstract

Rabbit whey acidic protein has been purified from whey using an AcA54 column. The purified whey acidic protein had an amino acid composition in agreement with the previously defined cDNA sequence. An antibody against whey acidic protein was raised in guinea pig. This antibody did not crossreact with mouse or cow milk or with rabbit alpha s1-casein and beta-casein. Whey acidic protein concentration was measured in rabbit milk using the antibody with a radioimmunoassay. The concentration of whey acidic protein in rabbit milk was 15 mg/ml, whereas the concentrations of alpha s1-casein and beta-casein were 16 and 45 mg/ml, respectively. The concentration of the three proteins was also evaluated in culture medium of rabbit primary mammary cells. The three proteins were induced by prolactin alone. Glucocorticoids amplified the prolactin effect on whey acidic protein more intensively than on caseins. The three proteins were present in mammary extract from virgin rabbit. The concentration of these proteins was lower at d 8 and 14 of pregnancy, and it was very high at d 25 of pregnancy. Whey acidic protein was undetectable in blood of virgin, weaned, and midpregnant females and of males. Whey acidic protein was present in blood of lactating rabbits, but alpha s1-casein and beta-casein were not detectably present in rabbit blood at the examined physiological states.

Rabbit milk: A review of quantity, quality and non-dietary affecting factors

“…After numerous attempts to identify the various types of casein present in rabbit milk (Allais and Jollès, 1970;Majumder and Ganguli, 1970;Testud and Ribadeau-Dumas, 1973;Al Sarraj et al, 1978;Dayal et al, 1982;Baranyi et al, 1995;Grabowski et al, 1991, Virag et al, 1996, 4 types can be clearly distinguished now: a S1 -casein, a S2 -casein, a-casein and k-casein. Total of caseins represent about 90 g/l with a specific contribution for example of 45 g/l of b-casein and 16 g/l of a S1 -casein (Grabowski et al, 1991). Virag et Average composition of lactation weeks 1-3 (Table 2).…”

Effect of litter size and bacitracin administration on tissue protein synthesis of lactating rabbit does

“…In addition, some proteins are synthesised in other tissues (mainly liver) and then transported via plasma to the mammary gland. The gland synthesises mostly a s1 -casein and b-casein plus some other proteins, relevant in ruminants but of minor importance in lagomorphs (Grabowski et al, 1991). The absolute synthesis of protein (15.06 g/day; Table 3) exceeds the secreted casein (13.9 g/day) but when allowance is made for WAP, reported to comprise 10% of total protein synthesised in milk (Grabowski et al, 1991), then much of the synthesis can be accounted.…”

“…The gland synthesises mostly a s1 -casein and b-casein plus some other proteins, relevant in ruminants but of minor importance in lagomorphs (Grabowski et al, 1991). The absolute synthesis of protein (15.06 g/day; Table 3) exceeds the secreted casein (13.9 g/day) but when allowance is made for WAP, reported to comprise 10% of total protein synthesised in milk (Grabowski et al, 1991), then much of the synthesis can be accounted. In support of previous reports in other species (Sampson et al, 1986;De Santiago et al, 1991), the mammary gland had a higher FSR than liver.…”

A Transgenic Mouse Model for Investigating the Response of the Upstream Region of Whey Acidic Protein (WAP) Gene to Various Steroid Hormones

“…Whey acidic protein (WAP) is the major whey protein in the milk of mice, rats, rabbits and camels [1][2][3][4][5][6][7][8]; it has not been found in the milk of swine or other livestock. The WAP gene possesses powerful regulatory elements and its expression is regulated by a complex interaction of several lactogenic hormones [9].…”