Megafauna of the German exploration licence area for seafloor massive sulphides along the Central and South East Indian Ridge (Indian Ocean).

BACKGROUND: The growing interest in mineral resources of the deep sea, such as seafloor massive sulphide deposits, has led to an increasing number of exploration licences issued by the International Seabed Authority. In the Indian Ocean, four licence areas exist, resulting in an increasing number of new hydrothermal vent fields and the discovery of new species. Most studies focus on active venting areas including their ecology, but the non-vent megafauna of the Central Indian Ridge and South East Indian Ridge remains poorly known.In the framework of the Indian Ocean Exploration project in the German license area for seafloor massive sulphides, baseline imagery and sampling surveys were conducted yearly during research expeditions from 2013 to 2018, using video sledges and Remotely Operated Vehicles. NEW INFORMATION: This is the first report of an imagery collection of megafauna from the southern Central Indian- and South East Indian Ridge, reporting the taxonomic richness and their distribution. A total of 218 taxa were recorded and identified, based on imagery, with additional morphological and molecular confirmed identifications of 20 taxa from 89 sampled specimens. The compiled fauna catalogue is a synthesis of megafauna occurrences aiming at a consistent morphological identification of taxa and showing their regional distribution. The imagery data were collected during multiple research cruises in different exploration clusters of the German licence area, located 500 km north of the Rodriguez Triple Junction along the Central Indian Ridge and 500 km southeast of it along the Southeast Indian Ridge.

Three new species of the genus Dendronotus from Japan and Russia (Mollusca, Nudibranchia).

Three new species of the genus Dendronotus are described from the North Pacific waters of Japan and Russia. For the first time since 1949, three new species, D. jamsteci sp. nov., D. zakuro sp. nov. and D. bathyvela sp. nov. are described from the waters of the Japanese Islands. D. zakuro sp. nov. was also discovered in the waters of Russia (Kamchatka). The descriptions of the new species D. jamsteci sp. nov. and D. zakuro sp. nov. are based on morphological and molecular data; D. bathyvela sp. nov. morphologically belongs to the group of D. robustus, D. velifer and D. patricki. This study revises our knowledge of North Pacific species of the genus Dendronotus, considerably expands the number of species worldwide and contributes to the multilevel fine-scale diversity concept.

A new species of Ernstia (Porifera: Calcarea) described from marine aquarium.

A new species of calcareous sponge, Ernstia pyrum sp. nov. (Calcarea, Calcinea, Clathrinida, Clathrinidae) is described from marine reef aquarium. It is assumed that its type locality is Indonesia. Molecular data render this species as a member of the genus Ernstia, although its morphology deviates in significant points from the original definition of the genus. In particular Ernstia pyrum sp. nov. has a clear atrial cavity not lined with choanocytes (true atrium), a feature not reported before for this genus.

A new Culeolus species (Ascidiacea) from the NE Pacific, California.

The paper describes Culeolus barryi n. sp. (Ascidiacea: Pyuridae), a species photographically documented in situ and collected in the northeast Pacific, off the coast of California (USA). This species of stalked tunicate inhabits deepwater (1200 m) and is characterized by numerous gonads on each side of the body. It is most similar to C. nadejdae from the Sea of Okhotsk and C. sluiteri from Aleutian Islands. A brief overview of all Culeolus species is provided.

Shallow-water Ascidians from Matua Island (central Kuril Islands, NW Pacific), part 2.

The paper reports several ascidians, previously not known from central group of Kurile Islands, including two new species, Synoicum polyzoinum n. sp. and Aplidium matua n. sp. In order to systematize our knowledge on numerous members of these genera, reported from NW Pacific, we provide an overview of all Synoicum and Aplidium species, known from Far Eastern Seas of Russia, including comments on the species erroneously identified in the past.

Scoliorhapis stepanovi-new species of sea cucumber from the North-West Pacific (Holothuroidea: Synaptida: Chiridotidae: Taeniogyrinae) and some remarks on the genus Scoliorhapis.

New species Scoliorhapis stepanovi has been collected from depths of 10-23 m on the sandy bottom of Avacha Bay (east coast of Kamchatka), Paramushir Island (North Kuril Islands), and Matua Island (Middle Kuril Islands). It is unique in having sigmoid ossicles in the body wall with points at both ends (without an open-eye, and with the two points lying in a perpendicular plane). Such sigmoids do not occur in any other taeniogyrinid species. The two-pointed sigmoids are 80-115 µm in length, and are scattered in the body wall and not clustered. Probably the two-pointed sigmoids are underdeveloped typical sigmoid with open-eye. In the tentacles there are straight and C-shaped rods, sometimes branched at the ends, 70-90 µm in length. It is assumed that atypical two-pointed sigmoid ossicles may have been originated due to deviating from the usual course of sigmoid development in the middle stages. Scoliorhapis stepanovi resembles S. lindbergi. A key for species of Scoliorhapis is provided.

Identification of unusual peptides with new Cys frameworks in the venom of the cold-water sea anemone Cnidopus japonicus.

Sea anemones (Actiniaria) are intensely popular objects of study in venomics. Order Actiniaria includes more than 1,000 species, thus presenting almost unlimited opportunities for the discovery of novel biologically active molecules. The venoms of cold-water sea anemones are studied far less than the venoms of tropical sea anemones. In this work, we analysed the molecular venom composition of the cold-water sea anemone Cnidopus japonicus. Two sets of NGS data from two species revealed molecules belonging to a variety of structural classes, including neurotoxins, toxin-like molecules, linear polypeptides (Cys-free), enzymes, and cytolytics. High-throughput proteomic analyses identified 27 compounds that were present in the venoms. Some of the toxin-like polypeptides exhibited novel Cys frameworks. To characterise their function in the venom, we heterologously expressed 3 polypeptides with unusual Cys frameworks (designated CjTL7, CjTL8, and AnmTx Cj 1c-1) in E. coli. Toxicity tests revealed that the CjTL8 polypeptide displays strong crustacean-specific toxicity, while AnmTx Cj 1c-1 is toxic to both crustaceans and insects. Thus, an improved NGS data analysis algorithm assisted in the identification of toxins with unusual Cys frameworks showing no homology according to BLAST. Our study shows the advantage of combining omics analysis with functional tests for active polypeptide discovery.

Shallow-water Ascidians from Matua Island (central Kuril Islands, NW Pacific).

Fifteen species of ascidians were identified in the material collected at Matua Island. Two species are new, Botryllus flavus n. sp. and Distaplia matua n. sp. The first species occurs also at Kamchatka waters, while the second is probably an endemic of Kuril Islands. The genus Macrenteron Redikorzev, 1927 is synonymized with Aplidium Savigny, 1816 and a new name Aplidium macrenteron nom. nov. is proposed for its type species.

Sea anemone peptide with uncommon ß-hairpin structure inhibits acid-sensing ion channel 3 (ASIC3) and reveals analgesic activity.

Three novel peptides were isolated from the venom of the sea anemone Urticina grebelnyi. All of them are 29 amino acid peptides cross-linked by two disulfide bridges, with a primary structure similar to other sea anemone peptides belonging to structural group 9a. The structure of the gene encoding the shared precursor protein of the identified peptides was determined. One peptide, π-AnmTX Ugr 9a-1 (short name Ugr 9-1), produced a reversible inhibition effect on both the transient and the sustained current of human ASIC3 channels expressed in Xenopus laevis oocytes. It completely blocked the transient component (IC50 10 ± 0.6 µM) and partially (48 ± 2%) inhibited the amplitude of the sustained component (IC50 1.44 ± 0.19 µM). Using in vivo tests in mice, Ugr 9-1 significantly reversed inflammatory and acid-induced pain. The other two novel peptides, AnmTX Ugr 9a-2 (Ugr 9-2) and AnmTX Ugr 9a-3 (Ugr 9-3), did not inhibit the ASIC3 current. NMR spectroscopy revealed that Ugr 9-1 has an uncommon spatial structure, stabilized by two S-S bridges, with three classical ß-turns and twisted ß-hairpin without interstrand disulfide bonds. This is a novel peptide spatial structure that we propose to name boundless ß-hairpin.