28S rDNA haplotypes of males are distinct from those of androgenetic hermaphrodites in the clam Corbicula leana

• DOI: 10.1007/s00427-012-0395-7
• Publication Date: 2012-04-19T03:26:01Z
• Authors: Akira Komaru; Shoji Houki; Mitsuya Yamada; Takuya Miyake; Mayu Obata; Kouichi Kawamura
• Keywords: Male; 0301 basic medicine; 0303 health sciences; 03 medical and health sciences; Haplotypes; RNA, Ribosomal, 28S; Animals; Hermaphroditic Organisms; Corbicula; DNA, Mitochondrial; Triploidy

The clam Corbicula leana exists in two forms, hermaphrodites and males. Our previous study on mitochondrial DNA suggested that the male nuclear DNA might have derived from hermaphrodite C. leana relatively recently. To clarify the origin of males in the clam, sequences of the nuclear 28S rDNA divergent domain (which is 441-444 bp long) in androgenetic hermaphrodites and males and dioecious (bisexual) species were analyzed. Unexpectedly, the nuclear 28S rDNA haplotypes of males and hermaphrodites were distinct. Haplotype network analysis indicated that males and hermaphrodites are reproductively isolated from each other without sharing the same nuclear haplotype. These results support a hypothesis that the egg nuclear genome of androgenetic hermaphrodites is replaced by the male sperm genome, and only males develop after fertilization by a male spermatozoon.