Sulfated and sialylated N-glycans in the echinoderm Holothuria atra reflect its marine habitat and phylogeny.

Among the earliest deuterostomes, the echinoderms are an evolutionary important group of ancient marine animals. Within this phylum, the holothuroids (sea cucumbers) are known to produce a wide range of glycoconjugate biopolymers with apparent benefits to health; therefore, they are of economic and culinary interest throughout the world. Other than their highly modified glycosaminoglycans (e.g. fucosylated chondroitin sulfate and fucoidan), nothing is known about their protein-linked glycosylation. Here we used multistep N-glycan fractionation to efficiently separate anionic and neutral N-glycans before analyzing the N-glycans of the black sea cucumber (Holothuria atra) by MS in combination with enzymatic and chemical treatments. These analyses showed the presence of various fucosylated, phosphorylated, sialylated, and multiply sulfated moieties as modifications of oligomannosidic, hybrid, and complex-type N-glycans. The high degree of sulfation and fucosylation parallels the modifications observed previously on holothuroid glycosaminoglycans. Compatible with its phylogenetic position, H. atra not only expresses vertebrate motifs such as sulfo- and sialyl-Lewis A epitopes but displays a high degree of anionic substitution of its glycans, as observed in other marine invertebrates. Thus, as for other echinoderms, the phylum- and order-specific aspects of this species' N-glycosylation reveal both invertebrate- and vertebrate-like features.

Holothuria (Selenkothuria) parvispinea n. sp. (Echinodermata, Hololthuroidea, Holothuriidae) with key to the sub-genus Selenkothuria.

Description of a new species from Australia, belonging to the subgenus Selenkothuria (Holothuria, Aspidochirotida). A dichotomous key of the thirteen valid species included in the subgenus is also given. The species H. perrieri Thandar, 1977 and H. spinea Cherbonnier, 1988 are considered as non valid.

On the taxonomic status of Holothuria (Holothuria) tubulosa (s.s.) from the Algerian coast with the description of a new Mediterranean species, Holothuria (Holothuria) algeriensis n. sp. (Echinodermata: Holothuroidea: Holothuriidae).

In this study we redescribe the taxonomy of some holothuriid species collected from different localities of the Algerian coastal waters. Morphological (anatomical and endoskeletal) and previous molecular studies show the presence of two distinct morphotypes of Holothuria (Holothuria) tubulosa "A" "B". Morphotype "A" corresponds to the classical Holothuria (Holothuria) tubulosa Gmelin 1791, described by Koehler (1921) and hereafter referred to as H. (H.) tubulosa (s.s.), while morphotype "B", we believe, represents a new species, herein named H. (Holothuria) algeriensis n. sp. with characteristics significantly different from those of Holothuria (H.) tubulosa (s.s.). Both morphology and statistical analysis (Linear Discriminant Analysis) confirm significant differences between these two morphotypes. To visualize these differences, measurements made on ossicles of Holothuria (H.) tubulosa (s.s.) and Holothuria (H.) algeriensis n. sp. were compared with other species present in our collections, including the north-eastern Atlantic and Mediterranean Holothuria (Roweothuria) arguinensis Koehler Vaney, 1906, recently recorded from Algerian waters, the Mediterranean Holothuria (Roweothuria) poli Delle Chiaje, 1824 and Holothuria (Holothuria) stellati Delle Chiaje, 1824. We conclude that the two morphotypes of H. (H.) tubulosa are significantly different to warrant the recognition of a new species, H. (H.) algeriensis n. sp. and the linear discriminant analysis (LDA) of the five species demonstrate this.

A START-domain-containing protein is a novel marker of nervous system components of the sea cucumber Holothuria glaberrima.

One of the main challenges faced by investigators studying the nervous system of members of the phylum Echinodermata is the lack of markers to identify nerve cells and plexi. Previous studies have utilized an antibody, RN1, that labels most of the nervous system structures of the sea cucumber Holothuria glaberrima and other echinoderms. However, the antigen recognized by RN1 remained unknown. In the present work, the antigen has been characterized by immunoprecipitation, tandem mass spectrometry, and cDNA cloning. The RN1 antigen contains a START lipid-binding domain found in Steroidogenic Acute Regulatory (StAR) proteins and other lipid-binding proteins. Phylogenetic tree assembly showed that the START domain is highly conserved among echinoderms. We have named this antigen HgSTARD10 for its high sequence similarity to the vertebrate orthologs. Gene and protein expression analyses revealed an abundance of HgSTARD10 in most H. glaberrima tissues including radial nerve, intestine, muscle, esophagus, mesentery, hemal system, gonads and respiratory tree. Molecular cloning of HgSTARD10, consequent protein expression and polyclonal antibody production revealed the STARD10 ortholog as the antigen recognized by the RN1 antibody. Further characterization into this START domain-containing protein will provide important insights for the biochemistry, physiology and evolution of deuterostomes.

Diversity and function of aerobic culturable bacteria in the intestine of the sea cucumber Holothuria leucospilota.

Sea cucumbers play an important role in nutrient cycling of marine ecosystems by consuming sediments and moving sand, thus occupying a similar niche to earthworms in terrestrial ecosystems. However, our understanding of microbial diversity and functions associated with sea cucumbers is meager. Here, we isolated 141 bacterial strains under aerobic conditions using various media from the intestine of Holothuria leucospilota, a common sea cucumber in Japanese warm waters. By partial 16S rRNA gene sequences of the isolates, the isolates were tentatively affiliated with 55 described species. Among them, 23 species were common between 2 individuals of H. leucospilota. High diversity was observed in the genera Bacillus and Vibrio, which are often found in marine sediments, marine animals and other various environments. Most isolates showed various polysaccharide degradation activities and were able to grow under or were tolerant of anaerobic condition. We suggest that these aerobically isolated bacteria can play a role in digestion of detritus in aerobic and/or anaerobic regions of the intestine.

A new endosymbiotic bivalve (Heterodonta: Galeommatoidea), from Pacific holothurians.

A fourth known species of Entovalva (Mollusca: Galeommatoidea), found in the esophagus of Holothuria spinifera and Holothuria leucospilota from Nha Trang Bay, Viet Nam, is described. Morphologic comparisons with the 3 previously described species are presented and the first DNA sequences for Entovalva are provided. Entovalva nhatrangensis, n. sp., differs from Entovalva mirabilis Voeltzkow, 1890 in its body shape, folded outer body epithelium, and lack of ovary in the foot. It differs from Entovalva (Cycladoconcha) amboinensis (Spärk, 1931) in its body shape and folded outer body epithelium. It differs from Entovalva lessonothuriae Kato, 1998, in shape of its foot. Two partial cytochrome oxidase I sequences for species diagnostic use have been submitted to GenBank.