F. Gandolfi et al., COMPARATIVE-ANALYSIS OF CALF AND COW OOCYTES DURING IN-VITRO MATURATION, Molecular reproduction and development, 49(2), 1998, pp. 168-175
To determine possible causes of reported differences between developme
ntal competence of oocytes isolated from prepubertal (10- to 14-week-o
ld calves) and adult cows, three parameters were analysed, comparative
ly, during in vitro maturation (IVM): (1) oocyte diameter, (2) oocyte
energy metabolism, and (3) protein synthesis of oocytes and cumulus ce
lls. Cumulus-oocyte complexes were isolated from follicles of 3-5 mm i
n diameter in both age groups. Mean oocyte diameter was smaller (P < 0
.02) in calves than in cows (118.04 +/- 1.15 versus 122.83 +/- 0.74 mu
m). During the first 3 hr of IVM calf oocytes metabolised glutamine a
nd pyruvate at lower rates than adult oocytes, but after 24 hr of cult
ure, both molecules were metabolised at the same rate as for adult ooc
ytes. A significant decrease in protein synthesis, as measured by [S-3
5]methionine and [S-35]cysteine incorporation was recorded after 9 hr
of IVM in calf oocytes, while in adult oocytes a significant decrease
in protein synthesis was detected only after 24 hr. After the first 3
hr of maturation, proteins of 130, 26, and 24 kDa were more abundant i
n adult than in calf oocytes, while a protein of 55 kDa was more visib
le in calf than in adult oocytes. At the same time, among proteins new
ly synthesised by cumulus cells, molecules of 405, 146, 101, and 77 kD
a were more abundant in adults than in calves. In conclusion, calf ooc
ytes and cumulus cells showed several differences when compared with t
heir adult counterparts, which are consistent with their reported lowe
r developmental competence. (C) 1998 Wiley-Liss, Inc.