Developmental changes in acid proteases of the avian proventriculus

Abstract

Developmental changes in acid proteases in the chicken and quail proventriculus were studied. During embryonic stages, the specific acid protease activity of both species showed a peak a few days before hatching and decreased towards the end of the incubation period. The electrophoretic patterns of acid proteases changed considerably at these stages. Within 24 hr after hatching, the activity increased about 30 times that of embryonic stages. Concomitant with this rapid increase, was a shift of electrophoretic patterns to the adult type. This shift occurred even in nonfed, hatched fowls. Electrophoretic patterns and immunochemical studies with the purified chicken and quail pepsinogens revealed that the embryonic and adult proventriculi of both species have stage-specific and species-specific pepsinogens.

The differences between the localizations of MUC1, MUC5AC, MUC6 and osteopontin in quail proventriculus and gizzard may be a reflection of functional differences of stomach parts

“…Previous studies have shown that within 24 h after hatching, the peptic activity of the chick proventriculus was about 10 times that of the embryonic proventriculus of the 20-day embryo and increased at the same rate in the subsequent 24 h. The activity reached a plateau on the 3rd day after hatching. The specific activity of the adult proventriculus was only about three times that of the 2.5-day proventriculus (Yasugi et al 1979;Yasugi & Mizuno, 1981). This may explain the weak OPN immunoreactivity at hatching.…”

Absorption, transportation and digestion of egg white in quail embryos

“…Digestion of ovalbumin itself seems not to occur in the lumen, as observed by the immunoblotting tests. In the embryonic proventriculi, the specific activity of ‘embryonic’ pepsinogens showed a peak at days 12–13 in the quail and on day 15 in the chicken (Yasugi & Mizuno 1981). Pancreatic secretory activity seems to occur at corresponding stages in the chicken (Dieterlen‐Lièvre & Hadorn 1972; Baintner & Fehér 1974).…”

“…Pancreatic secretory activity seems to occur at corresponding stages in the chicken (Dieterlen‐Lièvre & Hadorn 1972; Baintner & Fehér 1974). However, ovalbumin and egg white might not be affected by proteolytic enzymes because of their low specific activity at these stages (Yasugi & Mizuno 1981), or perhaps because of inhibition by coexisting inhibitors (Baintner & Fehér 1974), or inadequate environmental conditions, in particular, low/high pH. Ovalbumin might in fact be transported with proteolytic enzymes into the yolk cell.…”

“…Moreover, no ovalbumin was present on days 17–18 on immunoblotting tests. After hatching (day 17), the specific activity of pepsinogens increased approximately 30‐fold, compared to that of the embryonic stages: enzyme species changed from embryonic to adult type at days 15–16 in the proventriculus of the quail (Yasugi & Mizuno 1981).…”

“…After studying the localization of various molecules of egg white in chickens, many authors (Saito et al 1965; Saito & Martin 1966; Baintner & Fehér 1974; Burley & Vadehra 1989; Sugimoto et al 1989) have speculated that the possible route for the migration of egg white may be the amnion–mouth–intestine–yolk system. The activities of pepsinogen (Yasugi & Mizuno 1981), trypsin, and chymotrypsin (Baintner & Fehér 1974) have been shown to be very low in the intestine of chicken embryos, and the egg white itself has been shown to contain trypsin inhibitor (Baintner & Fehér 1974), ovomucoid (Sugimoto et al 1984), and ovoinhibitor (Sugimoto et al 1996). Thus, the embryonic intestine is not the location where the digestion of egg white occurs.…”