ИСТИНА

Finding highly conserved elements (HCE) is a sophisticated computational problem. The authors proposed and used an original solving algorithm. This approach was applied to compete animal genomes, including early diverging animal lineages and close opistokonts as the outgroup: Homo sapiens, Drosophila melanogaster, Helobdella robusta, Schistosoma mansoni, Nematostella vectensis, Mnemiopsis leidyi, Trichoplax adhaerens, Amphimedon queenslandica, Capsaspora owczarzaki, Monosiga brevicollis, Salpingoeca rosetta. Maximum likelihood was applied to define HCE similarity, and the identified clusters robustly reproduced on HCE phylogenetic trees. One unique HCE was found rather unexpectedly only in Schistosoma mansoni, Mnemiopsis leidyi and Trichoplax adhaerens (named the “SMT group”), which represents a conserved domain of the putative protein poly(ADP-ribose) glycohydrolase involved in energy transport during complex spatial chromatin modifications in the nucleus. This observation may witness events of retaining functional genes in smaller genomes of not closely related lineages that probably undergo chromatin diminution during lifetime. On the other hand, only 7 HCEs avoid the SMT group but are present in all other studied metazoans. Those are positionally related to genes encoding an ATP-dependent helicase, valyl-tRNA synthetase, chimeric ubiquitin - 60S ribosomal protein L40, myosin heavy chain, AMP deaminase, pre-mRNA-processing splicing factor 8, elongation factor 2, and represent elements of the protein synthesis and oxygen electron transport in muscles. Research on HCEs may have important implications for phylogenomic studies, identification of genetic functions marking particular lineages, predictions of certain chromatin modification processes, and in other fields.