Seasonal variations of vitelline envelope proteins, vitellogenin, and sex steroids in male and female eelpout (Zoarces viviparus).

• The seasonal variations of vitelline envelope proteins, vitellogenin (VTG), and reproductive steroids were investigated in feral male and female eelpout, Zoarces viviparus. 17beta-Estradiol was present in both sexes with a peak in prespawning fish of 2.6 ng/ml in males and 2.7 ng/ml in females. 11-Ketotestosterone peaked in June at 4.2 and 0.47 ng/ml in males and females, respectively. A surge of testosterone was seen in both sexes in August, just prior to spawning. All steroid levels were low during early pregnancy. The vitelline envelope of the eelpout is composed of two major and one minor protein with molecular weights of 50, 55, and 44 kDa, respectively. An antiserum raised against solubilized vitelline envelope from turbot (Scophthalmus maximus) cross-reacted strongly with the 50-kDa protein from the isolated vitelline envelope and a similar-sized protein in female plasma and plasma from estrogenized males. Interestingly, the 50-kDa protein was also present at low levels in males as demonstrated by ELISA and Western blotting. In males, the 50-kDa protein did not follow the seasonal changes in 17beta-estradiol, but instead showed an almost perfect negative correlation with water temperature. VTG was present in female plasma as shown by Western blotting, but VTG was not detectable in male plasma despite relatively high endogenous estrogen levels. This suggests that the VTG induction by estradiol may be modulated by other factors in the eelpout.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

Animals

Blotting

Western

Enzyme-Linked Immunosorbent Assay

Estradiol

blood

Female

Gonadal Steroid Hormones

blood

Male

Perciformes

blood

Pregnancy

Seasons

Sex Characteristics

Testosterone

analogs & derivatives

blood

Vitelline Membrane

chemistry

Vitellogenins

blood

Publication and Content Type

ref (subject category)

art (subject category)