Seasonal variations in the nucleic acid content and RNA:DNA ratio of the gonad of the scallopPecten maximus

The RNA and DNA contents of the male and female portions of the gonad of the hermaphroditic marine bivalve molluscPecten maximus L. have been monitored throughout an annual reproductive cycle, from October 1985–September 1986, for a population from the Baie de Seine (Normandy, France). The DNA content of the male gonad was consistently 5 to 10 times greater than that of the female gonad, whilst the RNA content was lower. This underlines the basic premise that spermatogenesis involves the production of large numbers of small gametes, whereas oogenesis involves the production of few, large, synthetically active gametes. The RNA:DNA ratio is a good indicator of sexual maturation in the male gonad. Two peaks of RNA:DNA ratio were observed for the female gonad, possibly corresponding to gonad restoration and vitellogenesis.