engleski

Mitochondrial genome of Suberites domuncula: palindromes and inverted repeats are abundant in non-coding regions

The 26, 300-nucleotide sequence of the mitochondrial DNA (mtDNA) molecule of the demosponge Suberites domuncula (Olivi, 1792), the largest in size yet found in Porifera, has been determined. We describe the second hadromerid sponge mitochondrial genome that contains the same set of 41 genes as the hadromerid sponge Tethya actinia, including trnMe(cau), trnI2(cau), trnR2(ucu), and atp9, all of which are transcribed in the same direction. Furthermore, rRNA genes for the small and large ribosomal subunit are very long, rns is indeed the longest among Metazoa (1, 833 bp). Intergenic regions (IGR) comprise about 25% of S. domuncula mtDNA and include numerous direct and inverted repeats, as well as palindromic sequences. Overlapping genes and introns were not found. Phylogenetic analyses based on concatenated amino acid sequences from twelve mitochondrial protein genes strongly support the affiliation of S. domuncula to the order Hadromerida. Moreover, we have analysed and compared the three IGR up to 20 specimens of S. domuncula and Suberites ficus. S. ficus has been variously reported as being both synonymous with, and a separate species from S. domuncula. We have found polymorphisms in IGR of both species and long deletions (44 and 141 bp in size) in two IGR of S. ficus.

Porifera ; Hadromerida ; mtDNA ; mitochondrial evolution ; polymorphisms

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