L. Perez et Ip. Callard, REGULATION OF HEPATIC VITELLOGENIN SYNTHESIS IN THE LITTLE SKATE (RAJA-ERINACEA) - USE OF A HOMOLOGOUS ENZYME-LINKED-IMMUNOSORBENT-ASSAY, The Journal of experimental zoology, 266(1), 1993, pp. 31-39
An enzyme-linked immunosorbent assay (ELISA) was developed to detect v
itellogenin in skates. The antibody raised against the yolk protein li
povitellin was shown to recognize a sex-specific, estrogen-inducible 2
05 kD protein in plasma, previously identified in skate as vitellogeni
n. The detection limit of the assay was 31.3 ng/ml, similar to that of
radioimmunoassays for vitellogenin detection in other species. Using
the assay, vitellogenin levels were shown to be highest (241.8 +/- 26.
5 mug/ml) in the ovarian follicular phase, decreasing approximately 1-
2 days before ovulation to a low (173.1 +/- 22.9 mug/ml) during the lu
teal phase. Vitellogenin levels increased again approximately 1-2 days
before oviposition to 259.8 +/- 38.8 mug/ml. The effects of estrogen
and progesterone on hepatic vitellogenin production in normal and hypo
physectomized male skates were also investigated. Plasma vitellogenin
was not detectable in either intact or hypophysectomised male skates,
but increased with estradiol treatment (intact: 48.2 +/- 4.9 mug/ml vs
. hypophysectomised 252 +/- 10.6 mug/ml at day 8). Progesterone treatm
ent significantly (P < .01) attenuated the effect of estrogen on plasm
a vitellogenin levels in both intact (17 +/- 2.1 mug/ml) and hypophyse
ctomized (44.0 +/- 9.4 mug/ml) male skates.