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The dysbiosis of gut microbiota is closely related to the occurrence and development of inflammatory bowel disease (IBD). The manipulation of intestinal flora through prebiotics or probiotics is expected to...

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The complete mitochondrial genomes of Harpago chiragra and Lambis lambis (Strombidae) were determined with the size of 15,460 bp and 15,481 bp, respectively, and both sequences contained 13 protein-coding genes, 22 tRNAs, and two rRNAs. H. chiragra and L. lambis have similar mitochondrial features, corresponding to typical gastropod mitochondrial genomes, such as the conserved gene order, a high A + T content (66.22% for H. chiragra and 66.10% for L. lambis), and preference for A + T-rich codons. The start or termination codon of same protein-coding gene in H. chiragra was consistent with that in L. lambis, except for the termination codon of cox1 gene (TAG for H. chiragra and TAA for L. lambis) and the start codon of nad4 (GTG for H. chiragra and ATG for L. lambis). Pairwise sequence alignments detected different degrees of variations in H. chiragra and L. lambis mitochondrial genomes; and the two species had lower levels of genetic distance (0.202 for nucleotide sequence) and closest relationships as compared to Strombus gigas and Oncomelania hupensis. The 13 partitioned nucleotide sequences of protein coding genes of H. chiragra and L. lambis were aligned with representatives of the main lineages of gastropods and their phylogenetic relationships were inferred. H. chiragra and L. lambis share the same gene order as Littorinimorpha species, except Vermetoidea, which demonstrate a gene rearrangement in species. The reconstructed phylogeny supports three major clades within Littorinimorpha: 1) Stromboidea, Tonnoidea, Littorinoidea, and Naticoidea, 2) Rissooidea and Truncatelloidea, and 3) Vermetoidea. In addition, a relaxed molecular clock calibrated with fossils dated the diversification of Strombidae near 112 (44–206) Mya and a possible radiation is detected to occur between 45–75 Mya, providing implications to understand the Cenozoic replacement event (65–135 Mya) of Aporrhaidae by Strombidae.

The complete mitochondrial genome of Diadema setosum was sequenced by using long-PCR and primer walking methods. The complete mitochondrial genome is a 15,708 bp circular molecule, which contains 22 tRNAs, 2 rRNAs, and 13 protein-coding genes as well as a non-coding control region as in other urchin. The genome was composed of 27.5% A, 30.7% T, 24.3% C, and 17.5% G. The control region is 133 bp. Twelve of the 13 mitochondrial protein-coding genes use ATG as their start codon while the ATP8 gene starts with GTG. Six of the 13 mitochondrial protein-coding genes use TAA as their complete stop codon while seven of them use TAG as their complete stop codon.