GENDER-ASSOCIATED DIVERSE MITOCHONDRIAL-DNA MOLECULES OF THE MUSSEL MYTILUS-CALIFORNIANUS

The Pacific-rim, dioecious bivalve Mytilus californianus contains two distinct sequence types of mitochondrial (mt) DNA that are gender-limi ted in their occurrence. One type (F) is found in both females and mal es, but the second type (M) is strictly limited to males. Although F- and M-type mtDNAs occur in approximately equal proportion in testes, t here is a preponderance of M-type in sperm. Segments of the COI and ND 5 genes of F-type and M-type mtDNAs differ in nucleotide sequence by 2 1.1% and 31.6%, and in predicted amino-acid sequence by 7.9% and 27.1% , respectively. These latter observations raise hitherto unconsidered questions regarding the number of different variants of cytochrome c o xidase and NADH dehydrogenase that may occur in Mytilus non-gametic ma le cells.