Cold methane seeps create suitable habitat conditions for chemosymbiotic frenulate tubeworms, one of the groups of the family Siboglinidae Caullery, 1914 that can form extensive aggregations at seeps at the shelf of the Arctic seas. The present study provides the first data on the ratio of natural stable C, N, and S isotopes in tissues of the siboglinid tubeworm Oligobrachia haakonmosbiensis found in methane seep fields on the Laptev Sea shelf. Values of delta 13C, delta 15N, and delta 34S for various body parts, such as cephalic and abdominal regions, tissues, whole worms with their tubes, and also worms and tubes separated, fixed in 96% ethanol, have been obtained for O. haakonmosbiensis. The lowest isotopic composition values were recorded from bodies of O. haakonmosbiensis with their tubes collected in the coastal zone at a depth of 25 m (delta 13C = -72.7 +/- 1.9%o; delta 15N = -10.9 +/- 1.2%o; and delta 34S = -28.1 +/- 1.9%o). Such low values are suggested to be associated mainly with large amounts of dissolved organic matter near the Lena River estuary. Our analysis of stable C, N, and S isotopes of O. haakonmosbiensis from the Laptev Sea has shown that the major energy source for symbiotic bacteria of this tubeworm species is hydrogen sulfide.

A Pacific brittle star Ophiura sarsii has previously been shown to produce a chlorin (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (ETPA) (1) with potent phototoxic activities, making it applicable to photodynamic therapy. Using extensive LC-MS metabolite profiling, molecular network analysis, and targeted isolation with de novo NMR structure elucidation, we herein identify five additional chlorin compounds from O. sarsii and its deep-sea relative O. ooplax: 10S-Hydroxypheophorbide a (2), Pheophorbide a (3), Pyropheophorbide a (4), (3S,4S,21R)-14-Ethyl-9-(hydroxymethyl)-21-(methoxycarbonyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (5), and (3S,4S,21R)-14-Ethyl-21-hydroxy-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid (6). Chlorins 5 and 6 have not been previously reported in natural sources. Interestingly, low amounts of chlorins 1-4 and 6 could also be identified in a distant species, the basket star Gorgonocephalus cf. eucnemis, demonstrating that chlorins are produced by a wide spectrum of marine invertebrates of the class Ophiuroidea. Following the purification of these major Ophiura chlorin metabolites, we discovered the significant singlet oxygen quantum yield upon their photoinduction and the resulting phototoxicity against triple-negative breast cancer BT-20 cells. These studies identify an arsenal of brittle star chlorins as natural photosensitizers with potential photodynamic therapy applications.

The free sterol fraction from the deep-sea holothurian Orphnurgus cf glaber Walsh, 1891, has been isolated and studied by GC–MS. Sterols containing Δ7, Δ0, Δ5, polyunsaturated and 5,8-epidioxy modified cores were found. A high percentage of compounds with polyunsaturated cores distinguish this composition from those of previously studied holothurians. Almost all identified compounds had saturated side chains, which is also a specific feature of this fraction. Peculiarities of biosynthesis and metabolism of the found sterols are discussed.

The free sterol fraction from the deep-sea holothurian Orphnurgus cf glaber Walsh, 1891, has been isolated and studied by GC–MS. Sterols containing Δ 7 , Δ 0 , Δ 5 , polyunsaturated and 5,8-epidioxy modified cores were found. A high percentage of compounds with polyunsaturated cores distinguish this composition from those of previously studied holothurians. Almost all identified compounds had saturated side chains, which is also a specific feature of this fraction. Peculiarities of biosynthesis and metabolism of the found sterols are discussed. Keywords Hawaiian-Emperor chain , deep-sea holothurian , cf , sterol composition

The present paper considers a technology based on the deployment of ROV Comanche 18, a work-class unmanned underwater remotely operated vehicle, which allows efficient deep-sea research operations in conditions of strong near-bottom currents and over seamounts with rough topography. Specifics of planning of underwater operations, ROV piloting, organization of dives, and interactions with the mothership crew are discussed. The specially designed sampling tools that provide collection of high-quality scientific material and the elaborated software for providing ROV operators activities with intellectual and informational support are described. The paper presents the results of integrated studies of ecosystems formed on oceanic submarine rises, such as the guyots and seamounts of the Emperor Seamount Chain (North Pacific). These studies with the deployment of a ROV Sub-Atlantic Comanche 18 were carried out during a deep-sea research expedition in the Pacific Ocean organized by the A.V. Zhirmunsky National Scientific Center of Marine Biology FEB RAS.

The present paper records two new species of deep-sea soft corals, Heteropolypus annae sp. nov. and H. roseus sp. nov., from the area of the Kurile Islands, Sea of Okhotsk, Northwest Pacific. Distinctive characters for each new species are provided and depicted with scanning electron microscopy imaging. The present finding of previously undescribed species emphasizes the need for further surveys, particularly in deeper waters in the area to improve knowledge of the deep-sea Octocorallia fauna in the Far East seas. The distribution of species of Heteropolypus in the temperate Northwest Pacific and their taxonomy characters are discussed based on the published literature and own data. A modified diagnosis of the genus is proposed.

The article reports results of benthic research carried out in the Northwest Pacific in the Bering Sea using the remotely operated vehicle Comanche. The study concerns the distribution of dominant animals in the summit region and at the upper slope of four southern guyots of the Emperor Seamount Chain.

FISHING OR BREEDING. This question arose relatively recently, but in the last decade, mankind will have to lean more towards the second. Sea reserves of useful species are exhausted. One possible solution to this problem is marine farming. We proposed to investigate the larval development of three sea urchin species: Diadema setosum (Leske, 1778), D. savignyi (Audouin, 1829) (South China Sea), and Mesocentrotus nudus (A. Agassiz, 1864) (Japan Sea). The larvae of Diadema setosum and D. savignyi were very similar, and some differences could only be observed at the late pluteus stage. These sea urchins were developed through the modified pluteus, which only had two pairs of larval arms. The arms were very long - in D. setosum above 2 mm, and in D. savignyi about 5.5 mm. Larval development took about 45 days in D. setosum and 47–50 days in D. savignyi. In contrast, Mesocentrotus nudus (A. Agassiz, 1864) was developed through the pluteus larvae, which had some differences from the pluteus of the genus Strongylocentrotus. Their dimensions did not reach one millimetre. The larval development of Mesocentrotus nudus lasted about 30 days. Analysis of material and time costs has led to the conclusion that Mesocentrotus nudus is the most convenient for obtaining seed material. However, this species cannot be used for the tropical zone. The results of D. savignyi and D. setosum can be used to increase the number of cultivated species.

В статье рассматриваются результаты исследований донной фауны, проведенные в северо- восточной части Тихого океана с использованием телеуправляемого аппарата “Команч”. Исследовано распределение доминирующих животных на вершинах и в верхней части склона четырех южных гайотов Императорского хребта.

— The first comprehensive study of the deep-sea ecosystems of the Emperor Chain seamounts (the northwestern Pacific Ocean) was conducted in July–August 2019 by A.V. Zhirmunsky National Scientific Center of Marine Biology, FEB RAS. The expedition, using a remote-operated underwater vehicle Comanche 18 , was aimed at the study of distribution of typical underwater landscapes and key taxa of Octocorallia corals and Hexactinellida sponges in the vulnerable marine ecosystem of the seamounts. New data on the macrobenthos biodiversity and biogeographic characteristics of deep-sea corals and sponges, which are the dominant animals in the studied area, are presented. The survey has shown changes of the coral fauna in the latitudinal direction and obtained new data on the biogeographic boundary in the area of the Emperor Chain seamounts.

This paper provides descriptions of two new species of Calcigorgia gorgonians collected from the Sea of Okhotsk between 1973 and 2008. The new species are Calcigorgia herba sp. nov. and.. lukini sp. nov., belonging to the deep-water coral fauna of the temperate Northern Pacific. The taxonomy structure of the genus is reviewed and a comparative table is provided for all known species of Calcigorgia. The following taxonomic changes are made: the diagnosis of the genus was corrected from that given in Matsumoto et al. (2019); synonymization of C. simushiri Dautova, 2018 with C. spiculifera Broch, 1935 and inclusion of additional specimens in C. japonica Dautova, 2007 (both performed by Matsumoto et al. 2019) are assumed erroneous. The finding of previously undescribed species emphasizes the need for further surveys, particularly in deeper waters, to improve knowledge of the Octocorallia fauna in Far East seas. The distribution of Calcigorgia (Octocorallia, Acanthogorgiidae) is reviewed and presented based on field and collection studies published since 1935 as well as miscellaneous data from previous literature.

This paper provides descriptions of Calcigorgia gorgonians collected from the Sea of Okhotsk and shores of the Kurile Islands between 3 Aug. 1984 and 20 Aug. 1987. New species described are the deep-water gorgonians Calcigorgia matua sp. nov. and C. simushiri sp. nov., belonging to the temperate fauna of the North Pacific hemisphere. Specimens belonging to all species of the genus were examined and the distinctive characters for each one are provided and summarized in a table. A modified diagnosis of the genus is proposed. The finding of a previously undescribed species emphasizes the need of further surveys, particularly in shelf and deeper waters, in order to improve our knowledge of this neglected fauna in Far East seas.

The published data about the deep-water octocoral fauna of the cold temperate Northwest Pacific (particularly Far East seas) remains scarce and mostly presented in a few papers published before 1970. This paper gives a list of Octocorallia collected from the Kuril Basin of the Sea of Okhotsk and the Bussol Strait in 2015 during the SokhoBio 2015 expedition. The present paper records seven species, of which three new deep-sea octocoral species and two new genera are described: Ignis rubeus gen. et sp. nov. attributed to the family Haimeidae, Aspera rosea gen. et sp. nov. attributed to the family Nephtheidae, and Radicipes sakhalinensis sp. nov. of the family Chrysogorgiidae. Distinctive characters for each new taxon are provided and depicted with scanning electron microscopy imaging. The present finding of previously undescribed species emphasizes the need for further surveys, particularly in shelf and deeper waters, in order to improve knowledge of this neglected fauna in Far East seas. The diversity and distribution of deep-water Octocorallia in the temperate Northwest Pacific are discussed based on the published literature and own data.

Nine new sulfated triterpene glycosides, magnumosides A(1) (1), A(2) (2), A(3) (3), A(4) (4), B-1 (5), B-2 (6), C-1 (7), C-2 (8) and C-4 (9) as well as a known colochiroside B-2 (10) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (=Massinium) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of new glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated new glycosides were characterized by the non-holostane type lanostane aglycones having 18(16)-lactone and 7(8)-double bond and differed from each other by the side chains and carbohydrate moieties structures. Magnumoside A(1) (1) has unprecedented 20(24)-epoxy-group in the aglycone side chain. Magnumosides of the group A (1-4) contained disaccharide monosulfated carbohydrate moieties, of the group B (5, 6)-tetrasaccharide monosulfated carbohydrate moieties and, finally, of the group C (7-9)-tetrasaccharide disulfated carbohydrate moieties. The cytotoxic activities of the compounds 1-9 against mouse spleen lymphocytes, the ascites form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 cells as well as their hemolytic effects have been studied. Interestingly, the erythrocytes were more sensitive to the glycosides action than spleenocytes and cancer cells tested. The compounds 3 and 7 significantly inhibited the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. Moreover, the synergism of effects of radioactive irradiation and compounds 3 and 7-9 at subtoxic doses on proliferation of DLD-1 cells was demonstrated.

Two new monosulfated triterpene glycosides, magnumosides B3 (1) and B4 (2) and one new disulfated triterpene glycoside, magnumoside C3 (3) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (=Massinium) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of the glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated glycosides are characterized by the non-holostane type aglycones having 18(16)-lactone and 7(8)-double bond and differing from each other by the side chains structures and the quantity of sulfate groups in the carbohydrate chains. The cytotoxic activity of the compounds 1–3 against mouse spleen lymphocytes and ascite form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 as well as their hemolytic effects have been studied. Magnumoside B4 (2) greatly suppressed the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. The study on synergism of effects of radiation and compounds 1–3 on proliferation of DLD-1 cells showed that the tested compounds almost equally enhanced antiproliferative effect of radioactive irradiation.

Nine new sulfated triterpene glycosides, magnumosides A₁ (1), A₂ (2), A₃ (3), A₄ (4), B₁ (5), B₂ (6), C₁ (7), C₂ (8) and C₄ (9) as well as a known colochiroside B₂ (10) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (=Massinium) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of new glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated new glycosides were characterized by the non-holostane type lanostane aglycones having 18(16)-lactone and 7(8)-double bond and differed from each other by the side chains and carbohydrate moieties structures. Magnumoside A₁ (1) has unprecedented 20(24)-epoxy-group in the aglycone side chain. Magnumosides of the group A (1-4) contained disaccharide monosulfated carbohydrate moieties, of the group B (5, 6)-tetrasaccharide monosulfated carbohydrate moieties and, finally, of the group C (7-9)-tetrasaccharide disulfated carbohydrate moieties. The cytotoxic activities of the compounds 1-9 against mouse spleen lymphocytes, the ascites form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 cells as well as their hemolytic effects have been studied. Interestingly, the erythrocytes were more sensitive to the glycosides action than spleenocytes and cancer cells tested. The compounds 3 and 7 significantly inhibited the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. Moreover, the synergism of effects of radioactive irradiation and compounds 3 and 7-9 at subtoxic doses on proliferation of DLD-1 cells was demonstrated.

Nine new sulfated triterpene glycosides, magnumosides A1 (1), A2 (2), A3 (3), A4 (4), B1 (5), B2 (6), C1 (7), C2 (8) and C4 (9) as well as a known colochiroside B2 (10) have been isolated from the tropical Indo-West Pacific sea cucumber Neothynidium (=Massinium) magnum (Phyllophoridae, Dendrochirotida) collected in the Vietnamese shallow waters. The structures of new glycosides were elucidated by 2D NMR spectroscopy and mass-spectrometry. All the isolated new glycosides were characterized by the non-holostane type lanostane aglycones having 18(16)-lactone and 7(8)-double bond and differed from each other by the side chains and carbohydrate moieties structures. Magnumoside A1 (1) has unprecedented 20(24)-epoxy-group in the aglycone side chain. Magnumosides of the group A (1–4) contained disaccharide monosulfated carbohydrate moieties, of the group B (5, 6)—tetrasaccharide monosulfated carbohydrate moieties and, finally, of the group C (7–9)—tetrasaccharide disulfated carbohydrate moieties. The cytotoxic activities of the compounds 1–9 against mouse spleen lymphocytes, the ascites form of mouse Ehrlich carcinoma cells, human colorectal carcinoma DLD-1 cells as well as their hemolytic effects have been studied. Interestingly, the erythrocytes were more sensitive to the glycosides action than spleenocytes and cancer cells tested. The compounds 3 and 7 significantly inhibited the colony formation and decreased the size of colonies of DLD-1 cancer cells at non-cytotoxic concentrations. Moreover, the synergism of effects of radioactive irradiation and compounds 3 and 7–9 at subtoxic doses on proliferation of DLD-1 cells was demonstrated.

Diadema setosum (Leske, 1778) develops from small isolecithal eggs with a diameter of 84 +/- 3 mu m. Embryonic development took about 6.5-7h and finished when a blastula left the fertilization envelope and became a larva. At this stage, the first pigment cells had appeared. At 23h a prism developed; at 44h a pluteus with one pair of arms had appeared; at 45h of development plutei had two pairs of arms. The pigment cells colour the pluteus of D. setosum dark red. When 20-day-old larvae were mechanically stimulated, they flared their arms which may be defensive behaviour. During further development, the post oral arms of plutei grew to 1900 mu m or more. Metamorphosis took place at about 40-45days. At this time, five primary ambulacral podia were visible within the larval body. The duration of metamorphosis from the moment of larval settlement until the juvenile sea urchins began to move along the bottom was 40-60 min. The diameter of the test of the newly metamorphosed juvenile sea urchins was about 500 mu m.

Fatty acid (FA) markers are widely used for tracking trophic relationships in cold-water benthic ecosystems, but data on the lipid composition of soft corals and hydrocorals, which are important components of these ecosystems, are very limited. Lipid class and FA profiles of four soft coral families (eleven species) and one hydrocoral family (four species) from the northeastern part of the Sea of Okhotsk were studied for the first time and compared with their tropical counterparts. Among cold-water cnidarians, soft corals contained much more monoalkyldiacylglycerols but less triacylglycerols than hydrocorals. The lipid class profile of all azooxanthellate soft corals did not differ, whereas FA profiles of these corals from cold-water and tropical regions differed. The key FAs were arachidonic (20:4n-6) and eicosapentaenoic (20:5n-3) acids, followed by 24:5n-6 and 24:6n-3. Within the cold-water corals, a sharp difference in polyunsaturated FA (PUFA) profiles between Primnoidae species and other families (Nephtheidae, Paragorgiidae, and Acanthogorgiidae) was found. The high level of n-3 PUFAs (20:5n-3 and 24:6n-3) in Primnoidae and the high level of n-6 PUFAs (20:4n-6 and 24:5n-6) in other cold-water coral families indicated the substantial difference in a feeding behavior between these corals inhabiting the same biotope. Based on the FA markers, a dietary predomination of herbivorous zooplankton is assumed for Primnoidae. An opportunistic feeding on various food sources is supposed for other cold-water coral families studied. The lipid and FA profiles were found to be characteristic for tropical zooxanthellate reef-building and soft corals, azooxanthellate soft corals from tropical and cold-water regions, and Primnoidae among cold-water coral families.