高顶鳞皮蚌F和M型线粒体基因组全序列结构比较及双单亲遗传下的进化分析OA

Doubly uniparental inheritance(DUI)of mitochondrial DNA,a rare exception to the strict maternal inheri-tance typical in animals,occurs only in certain bivalve families and is characterized by distinct gender-associated mtDNA lineages through males(M-type)or females(F-type).Due to frequent undetection,M-type sequences remain underrepresented in GenBank,impeding deeper understanding of DUI phenomenon.In this study,we sequenced and analyzed the complete M and F mitogenomes of the freshwater mussel Lepidodesma languilati.The complete mito-chondrial genome sequences of the F-type and M-type in L.languilati were 15768 and 17008 bp in length,respectively.Both exhibited a strong AT bias,with an A+T content of approximately 64%.Each genome encoded 37 genes,includ-ing 13 protein-coding genes(PCGs),22 tRNAs,and 2 rRNAs.Twenty-six genes were located on the light strand and 11 on the heavy strand.Structural defects were observed in several tRNAs:both F and M-type trnS genes lacked the TψC loop,and the M-type trnY gene lacked the DHU arm.Relative synonymous codon usage(RSCU)analysis showed that TTT was the most frequently used codon in both F-type(RSCU=1.55)and M-type(RSCU=1.63)genomes.Phyloge-netic analysis clearly demonstrated that the F and M-type mitochondrial genomes form two distinct monophyletic clades.Selective pressure analysis suggests atp8 as a potential sex-differentiation-related gene.In summary,this study provides the first comprehensive characterization of the structural differences,base composition,codon usage patterns,and non-coding region organization between the F and M-type mitochondrial genomes of L.languilati,supporting a pattern of parallel evolution between the two genomes in phylogenetic context.These findings not only provide funda-mental data for further comparative and applied studies of the mitochondrial genome in this species,but also contribute to a deeper understanding of the DUI phenomenon.