抄録
Plasma IgM levels were monitored bimonthly for three years in individual male and female goldfish reared under natural conditions, with special reference to water temperature and seasonal reproductive cycle. Sexual maturation of the experimental fish occurred normallyin the spring of each year as judged by rises in plasma levels of gonadal steroids. Plasma IgM levels showed clear seasonal change, both in males and females: values became elevated during the period between spring and summer, and declined from autumn to winter. These changes are related, at least in part, to gonadal maturation in spring, since plasma IgM increased concurrently with the rise of steroid hormones, i.e., estradiol-17β and testosterone in females, and 11-ketotestosterone and testosterone in males. IgM levels also showed positive correlations with water temperature. An artificial increase in water temperature, from 5°C to 15°C or 25°C within one day, was seen to induce an acute rise in plasma IgM. These results suggest that the seasonal changes in plasma IgM levels in goldfish are related to both gonadal maturation and water temperature.
