Mitochondrial Large Ribosomal RNA Gene Research Articles

Mitochondrial DNA polymorphisms in the human pathogenic fungus Cryptococcus neoformans.

This study examined mitochondrial DNA (mtDNA) restriction site polymorphisms among 416 strains of the human pathogenic yeast Cryptococcus neoformans from the United States and Japan. The strains included 378 serotype A, 14 serotype D, 18 serotype AD, two serotype B, and two strains whose serotype could not be determined using current commercial monoclonal antibodies. Portions of two genes were examined: (1) the mitochondrial large ribosomal RNA gene (mtLrRNA) and (2) the NADH dehydrogenase subunit 2 ( ND2). To screen for polymorphisms among the 416 strains, the endonuclease MaeIII was used to digest the PCR-amplified mtLrRNA gene fragment and three endonucleases ( BanI, AluI, MseI) were used to digest the PCR-amplified ND2 gene fragment. Four mtDNA haplotypes were identified among these strains. All strains of serotype A had mtDNA haplotype I, strains of serotype D had haplotype II, and strains of serotype B had haplotypes III and IV. Of the two non-typable strains, one was haplotype I while the other was haplotype II. Among the strains of serotype AD, 14 were haplotype I and the other four were haplotype II. These results were discussed in the context of recent findings regarding the origins of serotype AD strains and the observed uniparental mtDNA inheritance in laboratory crosses between strains of serotypes A and D.

Intraspecific variation in sibling species of Simulium venustum and Simulium verecundum complexes (Diptera: Simuliidae) revealed by the sequence of the mitochondrial 16S rRNAgene

A portion of the mitochondrial large ribosomal RNA gene was amplified and sequenced (460 base pairs) for 10 individuals of each of nine samples of black flies representing three sibling species of the Simulium venustum complex (CC, CC3, and AC(gB)) and two sibling species of the Simulium verecundum complex (ACD = Simulium rostratum and AA). Mitochondrial DNA haplotype heterogeneity was observed in all but the sample of S. verecundum AA from New Hampshire. The sample of S. venustum CC3 had a significantly larger number of haplotypes than other samples. A predominant haplotype was found in most samples except S. venustum CC3 and S. venustum CC from New Hampshire (nine haplotypes in the sample of S. venustum CC3 and two haplotypes with equal frequency in the sample of S. venustum CC from New Hampshire). The predominant haplotype was the same among the three samples of S. verecundum AA. Samples of S. venustum CC also shared haplotypes, but the predominant haplotype was different in each sample. Despite intraspecific variation, haplotypes are usually clustered on a conspecific basis.