Mitochondrial genome diversity in parasites

Mitochondrial genomes have been sequenced from a wide variety of organisms, including an increasing number of parasites. They maintain some characteri stics in common across the spectrum of life-a common core of genes related to mitochondrial respiration being most prominent-but have also developed a great diversity of gene content, organisation, and expression machineries. The characteristics of mitochondrial genomes vary widely among the differe nt groups of protozoan parasites, from the minute genomes of the apicomplex ans to amoebae with 20 times as many genes. Kinetoplastid protozoa have a s imilar number of genes to metazoans, but the details of gene organisation a nd expression in kinetoplastids require extraordinary mechanisms. Mitochond rial genes in nematodes and trematodes appear quite sedate in comparison, b ut a closer look shows a strong tendency to unusual tRNA structure and alte rnative initiation codons among these groups. Mitochondrial genes are incre asingly coming into play as aids to phylogenetic and epidemiologic analyses , and mitochondrial functions are being recognised as potential drug target s. In addition, examination of mitochondrial genomes is producing further i nsights into the diversity of the wide-ranging group of organisms comprisin g the general category of parasites. (C) 2000 Australian Society for Parasi tology Inc. Published by Elsevier Science. All rights reserved.