Departamento de Genética, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
Programa de Pós-graduação em Ciências Biológicas (Genética), Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
PeerJ. 2024 Nov 15;12:e18255. doi: 10.7717/peerj.18255. eCollection 2024.
Carnivorous sponges (Porifera, Demospongiae, Cladorhizidae), contrary to the usual filter-feeding mechanism of sponges, are specialized in catching larger prey through adhesive surfaces or hook-like spicules. The mitochondrial DNA of sponges overall present several divergences from other metazoans, and while presenting unique features among major transitions, such as in calcarean and glass sponges, poriferan mitogenomes are relatively stable within their groups. Here, we report and discuss the mitogenome of (Vacelet & Boury-Esnault, 1996), which greatly vary from its subordinal counterparts in both structure and gene order. This mitogenome is seemingly multipartite into three chromosomes, two of them as microDNAs. The main chromosome, chrM1, is unusually large, 31,099 bp in length, has a unique gene order within Poecilosclerida, and presents two rRNA, 13 protein and 19 tRNA coding genes. Intergenic regions comprise approximately 40% of chrM1, bearing several terminal direct and inverted repeats (TDRr and TIRs) but holding no vestiges of former mitochondrial sequences, pseudogenes, or transposable elements. The and genes are likely located in microDNAs thus comprising putative mitochondrial chromosomes chrM2, 291 bp, and chrM3, 140 bp, respectively. It is unclear which processes are responsible for the remarkable features of the of mitogenome, including a generalized gene rearrangement, long IGRs, and putative extrachromosomal genes in microDNAs.
肉食性海绵（多孔动物门，寻常海绵纲，Cladorhizidae）与通常的海绵滤食机制相反，通过粘性表面或钩状骨针专门捕捉较大的猎物。海绵的线粒体 DNA 与其他后生动物总体上存在一些差异，虽然在钙质海绵和玻璃海绵等主要进化中呈现出独特的特征，但多孔动物的线粒体基因组在其群体内相对稳定。在这里，我们报告并讨论了（Vacelet & Boury-Esnault，1996）的线粒体基因组，其结构和基因顺序与亚目相比有很大的差异。这个线粒体基因组似乎分为三个染色体，其中两个是微 DNA。主要染色体 chrM1 非常大，长度为 31,099 bp，在 Poecilosclerida 中具有独特的基因顺序，并呈现出两个 rRNA、13 个蛋白质和 19 个 tRNA 编码基因。基因间区约占 chrM1 的 40%，带有几个末端直接和反向重复（TDRr 和 TIRs），但没有前线粒体序列、假基因或转座元件的痕迹。和 基因可能位于微 DNA 中，因此分别构成假定的线粒体染色体 chrM2（291 bp）和 chrM3（140 bp）。目前尚不清楚哪些过程导致了 的线粒体基因组的显著特征，包括广泛的基因重排、长的 IGRs 和微 DNA 中的假定染色体外基因。
