Sea Urchin Strongylocentrotus Intermedius Research Articles

Transcriptome profiling reveals key roles of phagosome and NOD-like receptor pathway in spotting diseased Strongylocentrotus intermedius

Spotting disease is a common disease in the process of aquaculture and restocking of the sea urchin Strongylocentrotus intermedius and leads to mass mortality. To characterize the molecular processes and candidate genes related to spotting disease in S. intermedius, we conducted next-generation sequencing to assess the key genes/pathways in spotting diseased sea urchin (DUG) compared to healthy ones (HUG). A total of 321.1 million clean reads were obtained and assembled into 93,877 Unigenes with an N50 of 1185 bp, in which 86.48% of them matched to the genome sequence of the sea urchin S. purpuratus and 27,456 Unigenes mapped to Nr database. Salmon expression analysis revealed 1557 significantly differently expressed genes (DEGs) between DUG and HUG. These DEGs were enriched into 151 KEGG pathways including a core set of immune correlated pathways notably in phagosome and NOD-like receptor signaling. DUG displayed an obvious downregulation in these immune pathways. The expression patterns of six DEGs were confirmed by RT-qPCR, and the expressions were consistent with the results of RNA-seq. Furthermore, 15,990 SSRs were identified and a total of 235,249 and 295,567 candidate SNPs were identified from DUG and HUG, respectively. All these results provided basic information for our understanding of spotting disease outbreak in sea urchin.

Features of group growth for gray sea urchin (Strongylocentrotus interme¬dius) at the northwestern coast of the Japan Sea

Comparative study of growth rate and size-age structure of gray sea urchin Strongylocentrotus intermedius is conducted for six its aggregations along Primorye coast on the data collected in diving surveys in 2015–2017. Some aspects of the method of the sea urchin individual age determination by concentric growth bands on interambulacral plates of its carapace are discussed (the plates are processed by M. Jensen method). The group growth is described with Bertalanffy equation. Considerable spatial variability of the growth rate is found between the aggregations that provides some distinctions in size structure of the sea urchins. The highest growth rate is observed for three habitats: Kreyser Rock Island — Cape Lisuchenko, Oprichnik Bay — Cape Grozny, and Cape Sosunov — Plitnyak Bay, where the sea urchins reach the commercial size mostly at the age from 3.5+ to 4.5+. On the contrary, 50 % of the sea urchins become large enough for commercial fishery at the age of 6+ in the Ezhovaya Bay, and the lowest growth rates are noted at Cape Yuzhny and Cape Nadezhda where the majority of sea urchins never reach the commercial size. The maximum age of S. intermedius (19 years) is registered for a specimen with size 73 mm caught at Cape Sosunov. Mean and maximum sizes of individuals in the aggregations of slow-growing S. intermedius are lower than in the aggregations with comparatively high growth rates; such aggregations are also distinguished by lack of commercially-sized individuals. Age structure of all aggregations shows strong irregularity of annual recruitment, particularly low portion of the sea urchins at the age of 1+ is noted. Anyway, the frequency goes down from the age of 7+...9+ that indicates mass elimination of elder animals.

Predation by the gull Larus crassirostris on benthic invertebrates: First report of avian predation on the abalone Haliotis discus hannai

AbstractWe conducted field surveys to study avian predation on invertebrates inhabiting the intertidal and shallow subtidal zones in Otsuchi Bay on the Sanriku Coast. The black‐tailed gull Larus crassirostris was the most frequently observed avian predator, and we observed the gull actively foraging on benthic invertebrates at the study site. In particular, we found frequent predation activities by the black‐tailed gull on the abalone Haliotis discus hannnai. The abalone accounted for 56.3% of the total amount of the prey remains, and the sea urchin Strongylocentrotus intermedius and mussel Mytilus galloprovincialis were also major components of the prey remains and accounted for 14.6% and 11.8% of the total number, respectively. While the gull preys on the abalone over a wide size range (27.0–105.7 mm shell length), smaller size class abalone individuals (<40 mm shell length) were dominant in prey remains compared to the live abalone surveyed in the surrounding habitats. Among four time periods in a day, predation rate on the abalone was highest in the late afternoon. Predation rate on the abalone was higher on rising tides than falling tides, although no clear relationship was confirmed between the predation rate and the tidal height. The predation by the black‐tailed gull might have large impacts on the shallow rocky reef ecosystem.

Effects of UV-B radiation on fitness related behaviors of the sea urchin Strongylocentrotus intermedius

Ozone depletion induced by anthropogenic gases has been increasing the transmission of solar ultraviolet-B radiation (UV-B, 280–315 nm) through the atmosphere, which may impact the fitness of marine invertebrates in intertidal and shallow waters. To our knowledge, however, the responses of fitness related behaviors to UV-B radiation at different intensities have been rarely studied in marine invertebrates. For the first time, the present study investigated the effects of exposure of one hour to UV-B radiation at different intensities on foraging behavior, Aristotle’s lantern reflex and righting behavior of the sea urchin Strongylocentrotus intermedius. Exposure of one hour to UV-B radiation at 10 μW/cm2 significantly reduced foraging behavior. An intensity dependent effect of exposure to UV-B radiation was found in the duration of the Aristotle’s lantern reflex. Exposure to UV-B radiation at 20 μW/cm2 for one hour significantly reduced the duration of the Aristotle’s lantern reflex, but 10 μW/cm2 did not. There was no significant difference of righting response time among sea urchins exposed to 0, 10 and 20 μW/cm2 for one hour. To test potential carryover effects, the behavioral traits were re-measured three days later. We found significant carryover effects of UV-B radiation on foraging time and righting response time, but not on the duration of the Aristotle’s lantern reflex. The present study indicates that a brief exposure of one hour to UV-B radiation can significantly affect the duration of Aristotle’s lantern reflex, righting response time and foraging behavior of a sea urchin, although the immediate impacts and carryover effects were highly trait dependent. This study provides new information into the behavioral responses of marine invertebrates to exposure to UV-B radiation. Future studies should be carried out to investigate long-term carryover effects of UV-B radiation on behavioral and physiological fitness related traits.

Carryover effects of short-term UV-B radiation on fitness related traits of the sea urchin Strongylocentrotus intermedius

Carryover effects of UV-B radiation are largely unknown in marine invertebrates, despite the ecological importance. For the first time, we investigated fitness related traits of the sea urchin Strongylocentrotus intermedius 8 weeks after short-term (1 h) UV-B radiations (0, 10 and 20 µW cm−2). Short-term UV-B radiations had significant negative effects on survival, food consumption, test diameter, test height, test height:test diameter, gonad weight and crude protein of gonads of S. intermedius, despite of the absence of UV-B radiation for 8 weeks. Survival, food consumption and crude protein of gonads were significantly lowest in S. intermedius exposed to UV-B radiation at 20 µW cm−2, highlighting that 20 µW cm−2 is a dangerous UV-B radiation intensity for the fitness of sea urchins (at least S. intermedius). Gonads were significantly more sensitive to UV-B radiation than the gut. The present study increases our understanding of carryover effects of UV-B radiations on sea urchins and provides valuable information into marine environmental safety.

Transgenerational effects of heavy fuel oil on the sea urchin Strongylocentrotus intermedius considering oxidative stress biomarkers

Stranding of oil onto a coastline after an oil spill threatens the health of marine benthic organisms. Here, the transgenerational effects of exposure to stranded heavy fuel oil (HFO) on the sea urchin Strongylocentrotus intermedius were assessed. The column containing gravel coated with HFO was prepared in the laboratory to simulate HFO-contaminated gravel shorelines. Adult sea urchins were exposed for 21 days to either a HFO-oiled gravel column at the oil loading of 3000 μg oil/g gravel or a non-HFO-oiled gravel column (as the control treatment) and then offspring were either exposed to HFO or ambient seawater conditions. The sublethal exposure to HFO for 21 days induced polycyclic aromatic hydrocarbons (PAHs) accumulation in gonads, accompanied by increased levels of oxidative lipid, protein and DNA damage and a reduction in total antioxidant capacity. Analysis of gametes indicated that both maternal and paternal exposure could result in the transfer of PAHs and DNA damage to their offspring. Parental (maternal, paternal or both) exposure to HFO caused increases in malformation rates of offspring compared to those from control parents under ambient seawater condition. Continued HFO exposure in the offspring resulted in further increased malformation rates compared with those reared in ambient seawater, as well as oxidative lipid, protein and DNA damage. Furthermore, mother exposure history reduced the total antioxidant capacity of larvae to response to continued HFO exposure. Overall, the results suggest an increased sensitivity to toxic effects of HFO in larvae from exposed both parents compared with those from control parents in S. intermedius, which may consequently affect the recruitment and population maintenance.

Extremely stable high molecular mass soluble multiprotein complex from eggs of sea urchin Strongylocentrotus intermedius with phosphatase activity.

It was proposed that most biological processes are performed by different protein complexes. In contrast to individual proteins and enzymes, their complexes usually have other biological functions, and their formation may be important system process for the expansion of diversity and biological functions of different molecules. Identification and characterization of embryonic components including proteins and their multiprotein complexes seem to be very important for an understanding of embryo function. We have isolated and analyzed for the first time a very stable multiprotein complex (SPC; approximately 1100kDa) from the soluble fraction of extracts of the sea urchin embryos. By fast protein liquid chromatography (FPLC) gel filtration the SPC was well separated from other extract proteins. Stable multiprotein complex is stable in different drastic conditions but dissociates moderately in the presence of 8M urea+1.0M NaCl. According to sodium dodecyl sulfate polyacrylamide gel electrophoresis data, this complex contains many major, moderate and minor proteins with molecular masses from 10 to 95kDa. The SPC was destroyed by 8M urea or SDS, and its components were separated using thin layer chromatography, ion-exchange chromatography, gel filtration, and reverse phase chromatography. Using matrix-assisted laser desorption/ionization mass spectrometry of partially dissociated SPC, it was shown that the complex contains not only proteins (10-95kDa) but also few dozens of peptides with molecular masses from 2 to 9.5kDa. Short peptides form very strong complexes, which at the treatment of SPC with urea or SDS can be partially break down into smaller complexes having different peptide compositions. Reverse phase chromatography of these complexes after all type of abovementioned chromatographies led to detection from 6 to 11 distinct peaks corresponding to new complexes containing up to a few dozens of peptides. The SPCs possess alkaline phosphatase activity. Progress in the study of embryos protein complexes can help to understand their biological functions.

Low-dose action of tryptanthrin and its derivatives against developing embryos of the sea urchin Strongylocentrotus intermedius.

Nine tryptanthrin derivatives, including tryptanthrin itself, were synthesized using different methods, including oxidation of the corresponding isatins to obtain 1-4, the reaction of tryptanthrin 1 with hydrazine and its derivatives to obtain 5-7, and aldol condensation of 1 with acetone and methylethylketone to obtain 8 and 9. The action of 1-9 in doses corresponding to the IC50 against developing embryos of the sea urchin Strongylocentrotus intermedius and in the sperm test allowed us to estimate to potency of all the compounds and to determine which were cytotoxic. In addition, these studies showed that compounds 3, 4, 8, and 9 had a stimulatory effect at lower doses. In particular, the tryptanthrin derivatives stimulated the larval stages of development in surviving embryos at concentrations lower than the IC50.

Higher Dietary Arachidonic Acid Levels Improved the Growth Performance, Gonad Development, Nutritional Value, and Antioxidant Enzyme Activities of Adult Sea Urchin (Strongylocentrotus intermedius)

The gonads of sea urchins (Strongylocentrotus intermedius) are characterized by high levels of arachidonic acid (ARA, 20:4n-6) and eicosapentaenoic acid (EPA, 20:5n-3). However, to our knowledge, little information is available regarding the physiological response of adult sea urchins to dietary ARA. In the present study, four dietary feeds were formulated with graded ARA (0, 0.5%, 1%, and 2% dry diet). Each diet was randomly allocated to three cages during a 56-day feeding experiment. The results showed that the sea urchin weight gain rate (WGR) and the gonadosomatic index (GI) significantly increased as ARA was equal to or above 1.0% of dry diet (P 0.05), but was significantly lower than those fed with kelp (P < 0.05). These results suggested that relatively higher levels of ARA (1% dry diet) significantly promoted growth, gonad development, activities of antioxidant enzymes, as well as nutritional values (TEAA, TEAA/TNEAA, and PUFA) of adult S. intermedius.

Identification and characterization of microRNAs from the tube foot in the sea urchin Strongylocentrotus intermedius

MicroRNAs (miRNAs) play critical roles in regulating many bio-processes of eukaryotes. The sea urchin Strongylocentrotus intermedius (an important fishery resource) is of great economic importance in Japan, North Korea, Russia, and China. In the current study, miRNAs of tube foot in S. intermedius were firstly identified and characterized. Data in this study can provide more genomic information for the further understanding of the complex regulation network in sea urchins and present a new way for monitoring the health status of cultured sea urchins.

Parental exposure to heavy fuel oil induces developmental toxicity in offspring of the sea urchin Strongylocentrotus intermedius

The present study investigated the toxic effects of parental (maternal/paternal) exposure to heavy fuel oil (HFO) on the adult reproductive state, gamete quality and development of the offspring of the sea urchin Strongylocentrotus intermedius. Adult sea urchins were exposed to effluents from HFO-oiled gravel columns for 7 days to simulate an oil-contaminated gravel shore, and then gametes of adult sea urchins were used to produce embryos to determine developmental toxicity. For adult sea urchins, no significant difference in the somatic size and weight was found between the various oil loadings tested, while the gonad weight and gonad index were significantly decreased at higher oil loadings. The spawning ability of adults and fecundity of females significantly decreased. For gametes, no effect was observed on the egg size and fertilization success in any of the groups. However, a significant increase in the percentage of anomalies in the offspring was observed and then quantified by an integrative toxicity index (ITI) at 24 and 48 h post fertilization. The offspring from exposed parents showed higher ITI values with more malformed embryos. The results confirmed that parental exposure to HFO can cause adverse effects on the offspring and consequently affect the recruitment and population maintenance of sea urchins.

MORPHO-FUNCTIONAL CHARACTERISTICS OF GAMETES AND PRODUCING POSSIBILITIES OF MARINE ORGANISMS FOR THEIR REPRODUCTION IN MONO- AND POLYCULTURE

Reproduction of the sea urchins Strongylocentrotus intermedius, Mesocentrotus nudus, and the scallop Mizuhopecten yessoensis is considered in natural communities with various algae: red (Gracilaria verrucusa and Tichocarpus crinitus), brown (Sacharina cichorioides), and green (Vulva fenistrata). In these environments, their reproduction is influenced by exometabolites released by macrophytes, so the gametes with different production capacity could be formed and products of metabolism could impede their growth and development. To avoid these negative effects in polyculture, the cultured community should include species of different trophic levels forming a single food chain in which their exometabolites are utilized. The polyculture could be controlled by changing the number of species or influence on them by change of abiotic factors. In artificial polyculture, optimal conditions for reproduction and growth of cultivated species could be created, that provides the maximum production from a limited area.

The effects of 3 different microalgae species on the growth, metamorphosis and MYP gene expression of two sea urchins, Strongylocentrotus intermedius and S. nudus

As a result of the increase in demand for sea urchin gonads, which are considered a gourmet food, the sea urchin aquaculture industry has gradually expanded in some South American and Asian countries. This study investigated the growth, metamorphosis and MYP gene expression of larvae of two species of sea urchin (Strongylocentrotus intermedius and Strongylocentrotus nudus) fed with four microalgal diets: Chaetoceros muelleri, Dunaliella tertiolecta, Isochrysis galbana, and a mixture of the three. The larvae fed the C. muelleri and mixture diets were successfully raised to competence for metamorphosis and showed better stomach growth, development rates and metamorphosis rates than the larvae that were fed D. tertiolecta or I. galbana. The results also suggest that the larvae could accumulate long-chain polyunsaturated fatty acids (LC-PUFAs), such as docosahexaenoate (DHA; 22:6n-3), eicosapentaenoate (EPA; 20:5n-3) and arachidonate (ARA; 20:4n-6), either by the assimilation and retention of dietary fatty acids or by synthesis from α-linolenic acid (18:3n-3) and linoleic acid (18:2n-6). Moreover, an accumulation of n-6 and n-3 LC-PUFAs and higher ARA/EPA ratios in the larvae appeared to be associated with improved larval performance. The results also showed that the MYP gene expression levels in the larvae fed the C. muelleri and mixed diets were significantly higher than in the D. tertiolecta and I. galbana groups. In addition, the trend of the MYP gene expression in the different stages was 6-arm stage > 8-arm stage > 4-arm stage > fertilized eggs > prismatic stage. These results provide suggestions for diet selection for sea urchin larvae and the fatty acid composition of diets for urchin larvae, and they provide a reference for further study of the effects of diets on the gene expression of MYP in larvae.

Production, characterization and application of monoclonal antibodies to the coelomocytes of sea urchin Strongylocentrotus intermedius

Sea urchin is one of marine animals with high economic and great scientific research values. Axial organ is a glandular organ that has been presumed as coelomocytes origin site. In this paper, two monoclonal antibodies (3G10 and 6B3) against coelomocytes of sea urchin Strongylocentrotus intermedius were developed by hybridoma technique. The mAbs were characterized by indirect immunofluorescence assay test (IIFAT), flow cytometry (FCM) and western blot assay. Results showed that mAb 3G10 recognized a protein of a molecular weight of 17 kDa in the spherule cells, while mAb 6B3 reacted with a protein of a molecular weight of 35 kDa in the phagocytes. Furthermore, specificity analysis revealed that the two mAbs could react with the coelomocytes of sea urchin S. nudus and Hemicentrotus pulcherrimus, but not with those of other common echinoderms including sea cucumber Apostichopus japonicus and starfish Asterias rollestoni. To determine whether the coelomocytes exist in the axial organ of sea urchin, the IIFAT assays were carried out based on the two mAbs. Result showed that positive fluorescence signals were distributed in the organ. It was revealed that the axial organ was rich in coelomocytes, which suggests that the organ may play as a producing source or reservoir in the ontogenesis of coelomocytes of sea urchin.

Transgenerational effects of ocean warming on the sea urchin Strongylocentrotus intermedius

Transgenerational effects, which involve both selection and plasticity, are important for the evolutionary adaptation of echinoderms in the changing ocean. Here, we investigated the effects of breeding design and water temperature for offspring on fertilization, hatchability, larval survival, size, abnormality and metamorphosis of the sea urchin Strongylocentrotus intermedius, whose dams and sires were exposed to long-term (~15 months) elevated temperature (~3°C above ambient) or ambient temperature. There was no transgenerational effect on fertilization and metamorphosis of S. intermedius, while negative transgenerational effects were found in hatchability and most traits of larval size. Dam and sire effects were highly trait and developmental stage dependent. Interestingly, we found S. intermedius probably cannot achieve transgenerational acclimation to long-term elevated temperature for survival provided their offspring were exposed to an elevated temperature. The present study enriches our understanding of transgenerational effects of ocean warming on sea urchins.

SLAF-based high-density genetic map construction and QTL mapping for major economic traits in sea urchin Strongylocentrotus intermedius

Sea urchin (Strongylocentrotus intermedius) has long been a model species for developmental and evolutionary research, but only a few studies have focused on gene mapping. Here, we reported a high-density genetic map containing 4,387 polymorphism specific-length amplified fragment (SLAF) markers spanning 21 linkage groups (LG) for sea urchin. Based on this genetic map and phenotyping data for eight economic traits, 33 potentially significant QTLs were detected on ten different LGs with explanations ranging from 9.90% to 46.30%, partly including 10 QTLs for test diameter, six QTLs for body weight and eight QTLs for Aristotle’s lantern weight. Moreover, we found a QTL enrichment LG, LG15, gathering QTLs for test diameter, body weight, gonad weight, light orange-yellow color difference (≥E1) and light yellow color difference (≥E2). Among all QTLs, we genotyped four QTLs for test diameter, Aristotle’s lantern weight and body weight using High Resolution Melting (HRM) technology. Finally, we used the verified SNP marker (detected using SLAF sequencing) to explore their marker-assisted selection (MAS) breeding application potential and found that SNP-29 associated tightly with body weight and that heterozygous genotype was a dominant genotype, indicating that SNP-29 was a promising marker for MAS.

Identification and expression analysis of a TLR11 family gene in the sea urchin Strongylocentrotus intermedius.

In this study, a homolog of the TLR11 family gene from the sea urchin Strongylocentrotus intermedius (denoted as SiTLR11) was cloned and characterized. The full-length cDNA of SiTLR11 was 2096-bp long, which included 43bp of 5' untranslated region (UTR), 238bp of 3' UTR, and a putative open reading frame of 1815bp encoding a polypeptide of 604 amino acid residues. Representative domains such as leucine-rich repeat (LRR) (residues 108-249) and a cytoplasmic Toll-interleukin-1 receptor (TIR) (residues 429-571) domains were detected in the predicted amino acid sequence of SiTLR11. SiTLR11 transcript was widely distributed in all the tested tissues, including intestine, tube feet, gonad, coelomocytes, and peristomial membrane, with the highest expression level in the coelomocytes and peristomial membrane. After the sea urchin was injected with polyinosinic:polycytidylic acid (PolyI:C), the expression level of SiTLR11 in the coelomocytes increased significantly, reaching 1.96-fold the level of the control at 12h, but decreased to level below that of control at 24 and 48h. Injection of peptidoglycan (PGN) also led to increased expression of SiTLR11, which peaked at 12h, yielding an increase of 2.19-fold compared to the control group, and continued to increase at 24 and 48h. However, almost no differences in immunological activity were found in the groups challenged with lipopolysaccharides (LPS), Zymosan A (ZOA), or Vibrio fortis compared to the control. Taken together, the results strongly suggested that SiTLR11 was functionally involved in the immune response triggered by double-stranded RNA (dsRNA) viruses and Gram-positive bacteria.

Complete mitochondrial genome of the phenotypically-diverse sea urchin Strongylocentrotus intermedius (Strongylocentrotidae, Echinoidea)

The complete mitochondrial genomes are sequenced in two individuals representing two morphological forms, ‘usual’ (U) and ‘gray’ (G), of the short-spined sea urchin Strongylocentrotus intermedius. The genome sequences are 15,705 bp in size, and the gene arrangement, composition, and size are very similar to the other sea urchin mitochondrial genomes published previously. A low level of sequence divergence (Dxy = 0.0083 ± 0.0007) is detected between the forms. The GenBank (KC490912) mt genome of S. intermedius is much closer to the U form (Dxy = 0.0013 ± 0.0003) than to the G form (Dxy = 0.0085 ± 0.0006), demonstrating unique evolutionary trajectories for each form, which we previously suggested based on the bindin gene and symbiont analyses.

Synthesis and Cytotoxic Evaluation of Glucoconjugated Ethylmompain Derivatives

Quinone-carbohydrate conjugates of ethylmompain, a pigment of the sea urchin Echinothrix diadema, and its chlorinated analog were synthesized. The cytotoxic activity and contraceptive properties of the synthesized compounds have been investigated using the sperm and eggs of the sea urchin Strongylocentrotus intermedius.

The role of circadian rhythm and environmental factors in the regulation of sea urchin spawning

Simultaneous video recording of the sea urchin spawning behavior and recording of environmental factors enabled us to found synergism of the effects of circadian rhythm and phytoplankton on the spawning activity of the sea urchin Strongylocentrotus intermedius (Agassiz, 1864).