RESUMO
In contrast to bilaterian animals, non-bilaterian mitochondrial genomes contain atypical genes, often attributed to horizontal gene transfer (HGT) as an ad hoc explanation. Although prevalent in plants, HGT into animal mitochondrial genomes is rare, lacking suitable explanatory models for their occurrence. HGT of the mismatch DNA repair gene (mtMutS) from giant viruses to octocoral (soft corals and their kin) mitochondrial genomes provides a model for how barriers to HGT to animal mitochondria may be overcome. A review of the available literature suggests that this HGT was mediated by an alveolate endosymbiont infected with a lysogenic phycodnavirus that enabled insertion of the homing endonuclease containing mtMutS into octocoral mitochondrial genomes. We posit that homing endonuclease domains and similar selfish elements play a crucial role in such inter-domain gene transfers. Understanding the role of selfish genetic elements in HGT has the potential to aid development of tools for manipulating animal mitochondrial DNA.
Assuntos
Genoma Mitocondrial , Animais , Genoma Mitocondrial/genética , Transferência Genética Horizontal/genética , DNA Mitocondrial/genética , Mitocôndrias/genética , Sequências Repetitivas de Ácido Nucleico/genética , Filogenia , Evolução MolecularRESUMO
We present efficient and reproducible parallel strategies for preparing large quantities of pure heteroduplex plasmids containing defined mismatches. The strategies described involve the use of synthetic oligonucleotides, the commercially available pGEM-T plasmid, and nicking enzymes to prepare prerequisite ssDNA. Alternatively, bacterial packaging cell lines containing an engineered phagemid construct to produce ssDNA without the need of a helper phage were utilized, hence providing added flexibility and choice. These integrated approaches help to construct different mismatch substrates of choice in large quantities, thus enhancing the usability of mismatch repair assays and extending their range and accessibility to wider research groups.
Assuntos
Reparo de Erro de Pareamento de DNA , DNA de Cadeia Simples/química , Ácidos Nucleicos Heteroduplexes/química , Plasmídeos/química , DNA de Cadeia Simples/genética , Ácidos Nucleicos Heteroduplexes/genética , Plasmídeos/genéticaRESUMO
BACKGROUND: Mitogenome diversity is staggering among early branching animals with respect to size, gene density, content and order, and number of tRNA genes, especially in cnidarians. This last point is of special interest as tRNA cleavage drives the maturation of mitochondrial mRNAs and is a primary mechanism for mt-RNA processing in animals. Mitochondrial RNA processing in non-bilaterian metazoans, some of which possess a single tRNA gene in their mitogenomes, is essentially unstudied despite its importance in understanding the evolution of mitochondrial transcription in animals. RESULTS: We characterized the mature mitochondrial mRNA transcripts in a species of the octocoral genus Sinularia (Alcyoniidae: Octocorallia), and defined precise boundaries of transcription units using different molecular methods. Most mt-mRNAs were polycistronic units containing two or three genes and 5' and/or 3' untranslated regions of varied length. The octocoral specific, mtDNA-encoded mismatch repair gene, the mtMutS, was found to undergo alternative polyadenylation, and exhibited differential expression of alternate transcripts suggesting a unique regulatory mechanism for this gene. In addition, a long noncoding RNA complementary to the ATP6 gene (lncATP6) potentially involved in antisense regulation was detected. CONCLUSIONS: Mt-mRNA processing in octocorals possessing a single mt-tRNA is complex. Considering the variety of mitogenome arrangements known in cnidarians, and in general among non-bilaterian metazoans, our findings provide a first glimpse into the complex mtDNA transcription, mt-mRNA processing, and regulation among early branching animals and represent a first step towards understanding its functional and evolutionary implications.
Assuntos
Antozoários/genética , RNA de Transferência/genética , RNA/genética , Animais , Mapeamento Cromossômico , Regulação da Expressão Gênica , Ordem dos Genes , Genoma Mitocondrial , Fases de Leitura Aberta , RNA/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Mitocondrial , Transcrição Gênica , Transcriptoma , Regiões não TraduzidasRESUMO
Brachybacterium sp. GU-2 was isolated from the hard coral Porites lobata found in Apra Harbor, Guam, Micronesia. This genome sequence will be beneficial to understand the role of actinomycetes in coral holobionts. The Brachybacterium genome contains several gene clusters for bioactive compounds, including antibiotics.
RESUMO
Endozoicomonas sp. strain GU-1 was isolated from two separate staghorn coral (Acropora pulchra) colonies collected in Guam, Micronesia. Both isolates were grown in marine broth prior to DNA extraction and Oxford Nanopore Technologies (ONT) sequencing. Genomes were approximately 6.1 Mbp in size, containing highly similar gene content and matching sets of rRNA sequences.
RESUMO
Among the Facelinidae, the genus Cratena comprises nine valid species, four of them presenting a similar colour pattern with white body, reddish diverticula in the cerata and a pair of orange spots laterally on the head. Based on an integrative molecular phylogenetic and morphological approach two new species from western India are described, Cratena poshitraensis sp. nov. and Cratena pawarshindeorum sp. nov. Both species are similar to C. peregrina and C. minor but differ in body length, shape and size of orange spots on the head, C. poshitraensis sp. nov. presenting narrow spots dorsally projected on the base of each oral tentacle while C. pawarshindeorum sp. nov. has large and conspicuous orange spots that embrace dorsally and ventrally the base of the oral tentacles. According to our phylogenetic analysis, Facelina turned out paraphyletic and Cratena polyphyletic with an unclear relationship to Myja and Facelinidae sp.2, and Cratena pilata clustering distant to other Cratena species.