Dataset Information

The first complete mitogenome of the South China deep-sea giant isopod Bathynomus sp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.

ABSTRACT: In this study, the complete mitochondrial (mt) genome sequence of the South China deep-sea giant isopod Bathynomus sp. was determined, and this study is the first to explore in detail the mt genome of a deep-sea member of the order Isopoda. This species belongs to the genus Bathynomus, the members of which are saprophagous residents of the deep-sea benthic environment; based on their large size, Bathynomus is included in the "supergiant group" of isopods. The mt genome of Bathynomus sp. is 14,965 bp in length and consists of 13 protein-coding genes, two ribosomal RNA genes, only 18 transfer RNA genes, and a noncoding control region 362 bp in length, which is the smallest control region discovered in Isopoda to date. Although the overall genome organization is typical for metazoans, the mt genome of Bathynomus sp. shows a number of derived characters, such as an inversion of 10 genes when compared to the pancrustacean ground pattern. Rearrangements in some genes (e.g., cob, trnT, nad5, and trnF) are shared by nearly all isopod mt genomes analyzed thus far, and when compared to the putative isopod ground pattern, five rearrangements were found in Bathynomus sp. Two tRNAs exhibit modified secondary structures: The T?C arm is absent from trnQ, and trnC lacks the DHU. Within the class Malacostraca, trnC arm loss is only found in other isopods. Phylogenetic analysis revealed that Bathynomus sp. (Cymothoida) and Sphaeroma serratum (Sphaeromatidea) form a single clade, although it is unclear whether Cymothoida is monophyletic or paraphyletic. Moreover, the evolutionary rate of Bathynomus sp. (dN/dS [nonsynonymous mutational rate/synonymous mutational rate] = 0.0705) is the slowest measured to date among Cymothoida, which may be associated with its relatively constant deep-sea environment. Overall, our results may provide useful information for understanding the evolution of deep-sea Isopoda species.

SUBMITTER: Shen Y

PROVIDER: S-EPMC5355201 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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The first complete mitogenome of the South China deep-sea giant isopod Bathynomus sp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.

Shen Yanjun Y Kou Qi Q Zhong Zaixuan Z Li Xinzheng X He Lisheng L He Shunping S Gan Xiaoni X

Ecology and evolution 20170216 6

In this study, the complete mitochondrial (mt) genome sequence of the South China deep-sea giant isopod Bathynomus sp. was determined, and this study is the first to explore in detail the mt genome of a deep-sea member of the order Isopoda. This species belongs to the genus Bathynomus, the members of which are saprophagous residents of the deep-sea benthic environment; based on their large size, Bathynomus is included in the "supergiant group" of isopods. The mt genome of <i ...[more]

PMID: 28331594

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Project description:The marsupium, a brood pouch in peracarid crustaceans (Crustacea, Malacostraca) has evolved in terrestrial environment for providing nutrition and optimal conditions for embryogenesis. In the present study we give details on the histology and ultrastructure of its constituting elements such as oostegites and cotyledons. Marsupia of two different eco-morphological types of woodlice, namely the non-conglobating species Trachelipusrathkii Brandt, 1833 and the conglobating species Cylisticusconvexus De Geer, 1778 were investigated. Light microscopic (LM) studies showed some differences in the main structure of the two species' brood pouch: in Trachelipusrathkii, a 'clinger' type woodlice, the oostegites bend outwards during brood incubation as growing offspring require more space, while in Cylisticusconvexus, a 'roller' type isopod, the sternites arch into the body cavity to ensure space for developing offspring and still allowing conglobation of the gravid females. The quantitative analysis of the oostegites' cuticle proved that the outer part is about 2.5 - 3 times thicker compared to the inner part in both species. Electron microscopic (TEM) examinations show only small histological differences in the oostegites and cotyledon structure of the two species. Cellular elements and moderately electron dense fleecy precipitate are found in the hemolymph space between the two cuticles of oostegites. The cells contain PAS positive polysaccharide areas. TEM studies revealed some differences in the cotyledon ultrastructure of the two species. Cotyledons of Trachelipusrathkii consist of cells with cristate mitochondria and granular endoplasmic reticulum with cisterns. Cotyledons of Cylisticusconvexus consist of cells with densely cristate mitochondria and ribosomes attached to vesicular membrane structures. In both species cells with electron dense bodies were observed. We conclude that - besides the differences in marsupial shapes - the fine structure of the oostegites and cotyledons is hardly affected by the eco-morphological type, specifically the conglobating or non-conglobating character of the studied species.

Project description:BackgroundJuvenile gnathiid isopods are common ectoparasites of marine fishes. Each of the three juvenile stages briefly attach to a host to obtain a blood meal but spend most of their time living in the substrate, thus making it difficult to determine patterns of host exploitation. Sequencing of host blood meals from wild-caught specimens is a promising tool to determine host identity. Although established protocols for this approach exist, certain challenges must be overcome when samples are subjected to typical field conditions that may contribute to DNA degradation. The goal of this study was to address a key methodological issue associated with molecular-based host identification from free-living, blood-engorged gnathiid isopods-the degradation of host DNA within blood meals. Here we have assessed the length of time host DNA within gnathiid blood meals can remain viable for positive host identification.MethodsJuvenile gnathiids were allowed to feed on fish of known species and subsets were preserved at 4-h intervals over 24 h and then every 24 h up to 5 days post-feeding. Host DNA extracted from gnathiid blood meals was sequenced to validate the integrity of host DNA at each time interval. DNA was also extracted from blood meals of wild-fed gnathiids for comparison. Attempts were also made to extract host DNA from metamorphosed juveniles.ResultsUsing a cox1 universal fish primer set, known fish host DNA sequences were successfully identified for nearly 100% of third-stage juvenile gnathiid blood meals, digested for up to 5 days post-feeding. For second-stage juveniles, host identification was 100% successful when gnathiids were preserved within 24 h of collection. Fish hosts were positively identified for 69% of sequences from wild-fed gnathiid isopods. Of the 31% of sequences not receiving a ≥ 98 % match to a sequence in GenBank, 25 sequences were of possible invertebrate origin.ConclusionsTo our knowledge, this is the first study to examine the degradation rate of gnathiid isopod blood meals. Determining the rate at which gnathiids digest their blood meal is an important step in ensuring the successful host identification by DNA-based methods in large field studies.

Dataset Information

The first complete mitogenome of the South China deep-sea giant isopod Bathynomus sp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.

Publications

The first complete mitogenome of the South China deep-sea giant isopod <i>Bathynomus</i> sp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.

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