The methylation of Escherichia coli B transfer RNA in vitro by HeLa mitochondrial and cytoplasmic extracts was examined. The following differences were found. (a) The cytoplasmic extract methylated E. coli B tRNA to a much greater extent than did the mitochondrial extract. (b) The two extracts methylated different sites on E. coli B tRNA, thereby generating different methylated oligonucleotide ...

Background With some exceptions, mitochondria within the class Insecta have the same gene content, and generally, a similar gene order allowing the proposal of an ancestral gene order. The principal exceptions are several orders within the Hemipteroid assemblage including the order Thysanoptera, a sister group of the order Hemiptera. Within the Hemiptera, there are available a number of complet...

BACKGROUND Vertebrate mitochondrial genomes typically have one transfer RNA (tRNA) for each synonymous codon family. This limited anticodon repertoire implies that each tRNA anticodon needs to wobble (establish a non-Watson-Crick base pairing between two nucleotides in RNA molecules) to recognize one or more synonymous codons. Different hypotheses have been proposed to explain the factors that ...

Ascaris suum mitochondrial tRNA Met lacking the entire T stem was prepared by enzymatic ligation of two chemically synthesized RNA fragments. The synthetic tRNA could be charged with methionine by A.suum mitochondrial extract, although the charging activity was considerably low compared with that of the native tRNA, probably due to lack of modification. Enzymatic probing of the synthetic tRNA s...

About half of the mitochondrial DNA (mtDNA) mutations causing diseases in humans occur in tRNA genes. Particularly intriguing are those pathogenic tRNA mutations than can reach homoplasmy and yet show very different penetrance among patients. These mutations are scarce and, in addition to their obvious interest for understanding human pathology, they can be excellent experimental examples to mo...

Mitochondrial genome structure and organization are relatively conserved among metazoans. However, in many isopods, especially the terrestrial isopods (Oniscidea), the mitochondrial genome consists of both ∼14-kb linear monomers and ∼28-kb circular dimers. This unusual organization is associated with an ancient and conserved constitutive heteroplasmic site. This heteroplasmy affects the anticod...

The nucleotide sequence of a potato mitochondrial tRNA(Ile) has been determined. This tRNA has a lysidine-like minor nucleotide in the first position of the anticodon (position 34). The corresponding mitochondrial gene has been cloned and sequenced. This gene has a CAT anticodon which corresponds to methionine. The C residue in the anticodon must therefore be post-transcriptionally modified. Th...

A new quadrannulate species of Orobdella Oka, 1895, Orobdella naraharaetmagarum sp. n., from the mountainous region of western Honshu, Japan is described. Orobdella naraharaetmagarum is a small species with a body length of less than 5 cm. Phylogenetic analyses using nuclear 18S rRNA and histone H3, as well as mitochondrial cytochrome c oxidase subunit I, tRNA(Cys), tRNA(Met), 12S rRNA, tRNA(Va...