| Abstrakt: |
The largest and most diverse group of organisms in the animal kingdom are insects. Molecular markers are powerful tools that can tackle a wide range of insect ecological research issues. These provide a more effective way to study the massive unexplored genetic diversity and gene pool of insects. Recent trends of use of DNA marker techniques in varied domains of insect ecological studies demonstrate that mitochondrial DNA has made a significant contribution towards advancing our knowledge of genetic basis of insect diversity. To shed light on various aspects such as genome organization, base composition, gene rearrangements, and other features, we integrated 165 mitochondrial genomes (mitogenomes) consisting of 37 genes and a noncoding control region, from four major insect orders (Diptera, Lepidoptera, Orthoptera and Hemiptera) for comparative genomic analysis. The same 37 genes were found in the majority of mitochondrial genomes, however the order of genes was found disturbed in a few mitochondrial genomes. The nucleotide composition was found strongly biased towards AT content. Usually, protein-coding genes prefer ATA, ATT and ATG as a canonical start codon. However, inconsistency was observed for few PCGs particularly for COI. The loss of DHU arm was found specific to trnS1 gene. In Zeugodacus tau (Pumpkin fruit fly), trnF gene lacked the TΨC arm. Majority of the mismatches (G-U (most common), U-U, U-C, A-A, A-C, A-G and T-T) were found within the acceptor arm, DHU arm and anticodon stem of tRNA genes but few in TΨC stem. Interestingly, a unique gene rearrangement from trnW (W codes for Tryptophan) to trnU (U codes for Selenocysteine) in the mitochondrial genome of Boettcherisca peregrine (Flesh fly) was observed. AT-rich control region remains highly variable among most of the insects. The review is aimed to draw conclusions for better interpretations of mitochondrial DNA evolution. [ABSTRACT FROM AUTHOR] |
