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Abstract Morphologically cryptic and pseudo-cryptic species pose a challenge to taxonomic identification and assessments of species diversity and distributions. Such is the case for the sea cucumber Stichopus horrens, commonly confused with Stichopus monotuberculatus. Here, we used mitochondrial cytochrome oxidase subunit I (COI) and microsatellite markers to examine genetic diversity in Stichopus cf. horrens throughout the Philippine archipelago, to aid species identification and clarify species boundaries. Phylogenetic analysis reveals two recently diverged COI lineages (Clade A and Clade B; c. 1.35–2.54 Mya) corresponding to sequence records for specimens identified as S. monotuberculatus and S. horrens, respectively. Microsatellite markers reveal two significantly differentiated genotype clusters broadly concordant with COI lineages (Cluster 1, Cluster 2). A small proportion of individuals were identified as later-generation hybrids indicating limited contemporary gene flow between genotype clusters, thus confirming species boundaries. Morphological differences in papillae distribution and form are observed for the two species, however tack-like spicules from the dorsal papillae are not a reliable diagnostic character. An additional putative cryptic species was detected within Clade B-Cluster 2 specimens warranting further examination. We propose that these lineages revealed by COI and genotype data be referred to as Stichopus cf. horrens species complex.

Morphologically cryptic and pseudo-cryptic species pose a challenge to taxonomic identification and assessments of species diversity and distributions. Such is the case for the sea cucumber Stichopus horrens, commonly confused with Stichopus monotuberculatus. Here, we used mitochondrial cytochrome oxidase subunit I (COI) and microsatellite markers to examine genetic diversity in Stichopus cf. horrens throughout the Philippine archipelago, to aid species identification and clarify species boundaries. Phylogenetic analysis reveals two recently diverged COI lineages (Clade A and Clade B; c. 1.35–2.54 Mya) corresponding to sequence records for specimens identified as S. monotuberculatus and S. horrens, respectively. Microsatellite markers reveal two significantly differentiated genotype clusters broadly concordant with COI lineages (Cluster 1, Cluster 2). A small proportion of individuals were identified as later-generation hybrids indicating limited contemporary gene flow between genotype clusters, thus confirming species boundaries. Morphological differences in papillae distribution and form are observed for the two species, however tack-like spicules from the dorsal papillae are not a reliable diagnostic character. An additional putative cryptic species was detected within Clade B-Cluster 2 specimens warranting further examination. We propose that these lineages revealed by COI and genotype data be referred to as Stichopus cf. horrens species complex. [ABSTRACT FROM AUTHOR]

Stichopus ocellatus, known as eye-spotted sea cucumber, is a commercially important Stichopodidae holothuroid in Indo-Pacific region for its valuable nutrition and medicinal ingredients. However, because the taxonomic analyses based on morphological characters and molecular data within Aspidochirotida are limited, the deep-level evolutionary relationships of Aspidochirotida are still poorly understood. Here, for providing better insight of future evolutionary and taxonomic classification of Stichopodidae, we report the first complete mitogenome of S. ocellatus along with 37 annotated and characterized mitochondrial genes, and the phylogenetic analysis based on mitogenome data reveals sister relationship between S. ocellatus and S. monotuberculatus.

The mitochondrial genome is widely used to study the molecular evolution of and perform phylogenetic analyses on animals. In this study, the complete mitochondrial genome (mitogenome) of Stichopus naso was sequenced. The mitogenome was 16,239 bp in length and contained 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (rRNAs). The genome composition showed positive AT-skew (0.023) and negative GC-skew (−0.158). The order of the mitochondrial genes was consistent with those from the Stichopus and Isostichopus species, whereas it was different from those of other species of Aspidochirotida. The phylogenetic analysis, based on the nucleotide sequences of 13 PCGs through the methods of Bayesian inference (BI) and maximum likelihood (ML), indicated that S. naso has close relationships with S. horrens and S. monotuberculatus, and belongs to a member of Stichopodidae. Our study provides a reference mitogenome for further molecular evolution studies and phylogenetic research on sea cucumbers. [ABSTRACT FROM AUTHOR]

Stichopus ocellatus, known as eye-spotted sea cucumber, is a commercially important Stichopodidae holothuroid in Indo-Pacific region for its valuable nutrition and medicinal ingredients. However, because the taxonomic analyses based on morphological characters and molecular data within Aspidochirotida are limited, the deep-level evolutionary relationships of Aspidochirotida are still poorly understood. Here, for providing better insight of future evolutionary and taxonomic classification of Stichopodidae, we report the first complete mitogenome of S. ocellatus along with 37 annotated and characterized mitochondrial genes, and the phylogenetic analysis based on mitogenome data reveals sister relationship between S. ocellatus and S. monotuberculatus. [ABSTRACT FROM AUTHOR]

Length-weight relationships are commonly used to convert length measurements to body weights for data from population surveys, to generate estimates of biomass for stock assessment. These morphometric relationships assess whether increases in body weight are proportional to unit increases in length, providing an insight into growth. Few biological data are available for the nocturnally active sea cucumber, Stichopus cf. monotuberculatus , which is harvested throughout the Indo-Pacific region. This study assessed the morphometric relationships between body length and weight, and basal area and weight for three broad colour variants of S. cf. monotuberculatus at two reefs on the Southern Great Barrier Reef. Preparation of ossicles from the external tissues of the animals validated the species identification. All morphometric relationships were significant and revealed negative allometric growth (exponent, b , range = 2.17–2.42), as found in other holothuroids. Despite some deviance in length-weight relationships between colour types, the largely overlapping data points suggest that a single equation should be appropriate for weight estimation of S. cf. monotuberculatus. Length measurements alone were sufficient for estimating weight (r 2 = 0.80) because the addition of width measurements made no tangible improvement to the model fit. The findings indicate that this sea cucumber maintains a relatively consistent shape, with limited contraction of the body. These results will be useful for estimations of weight in future fishery surveys to estimate stock biomass and catch volumes. [ABSTRACT FROM AUTHOR]

Our knowledge of the ecology and habitat of juveniles of many sea cucumber species is limited, due to their cryptic habitats and differing color and shape from adults. In the present study, a juvenile specimen of the sea cucumber Thelenota anax H. L. Clark, 1921, collected from 30 m at Rukan Reef, Okinawa, Japan, is described. We confirmed specific identity using cytochrome oxidase subunit I (COI) sequences. We show that the pseudotable ossicles in Thelenota are table ossicles, and document synallactid-like ossicles not previously recorded in the Stichopodidae. [ABSTRACT FROM AUTHOR]

Extensive processing of sea cucumber causes body deformation of the marine organism, hence causing difficulties in species identification of processed sea cucumbers. Due to the copresence of cases of unlabelled or mislabelled sea cucumber products in Malaysian markets and worldwide, a study was conducted to determine the species identities of processed sea cucumbers from selected Malaysian markets using non-protein-coding 12S mitochondrial rRNA gene. Phylogenetic analyses based on the distance-based Neighbour Joining method, and the character-based methods i.e. the Maximum Parsimony method, Maximum Likelihood method, and the Bayesian Analysis method of 81 ingroup sequences representing 63 processed sea cucumber specimens, 13 fresh and processed reference samples for species identification, and five fresh additional specimens from Teluk Nipah Beach, Pangkor Archipelago and Manukan Island, Sabah suggested the presence of three main clusters i.e. a gamat family cluster consisting of family Stichopodidae (Stichopus horrens, Stichopus vastus, and Thelenota anax) and two clusters of timun laut family comprising family Holothuriidae (Holothuria (Mertensiothuria) leucospilota, Holothuria (Metriatyla) scabra, Holothuria (Metriatyla) lessoni, Holothuria (Halodeima) atra, and Holothuria (Halodeima) edulis) and family Caudinidae (Acaudina molpadioides). The outcomes of this study also highlighted the availability of 40 new 12S mitochondrial rRNA gene sequences deposited in the GenBank that can be utilised by the enforcement agencies to monitor and overcome the issues of species substitution and product mislabelling of processed sea cucumber products in Malaysian markets. [ABSTRACT FROM AUTHOR]

Abstract: Effective culturing and restocking of any commercial holothurian are dependent on understanding the biology and ecology of the species throughout its life history. Inherent differences between species require distinct strategies in larval and juvenile rearing. This study evaluated the effect of macroalgal and seagrass detritus as supplemental food on growth, feeding and sheltering behaviour, and biochemical composition of cultured Stichopus cf. horrens juveniles (2.6–3.8 g) under nursery rearing conditions. The addition of detritus to sediments did not significantly affect juvenile growth and body composition when compared to a biofilm‐only control. Average specific growth rates were positive throughout the experiment (1.58%–7.88% per day), however size variability, feeding rate, and sheltering behaviour differed significantly. Juveniles in treatments with macroalgal detritus had the highest coefficient of variation in weight (40%–51%) and a propensity to avoid sheltering near the sediments. This is presumably due to anoxic sediment conditions that developed in the macroalgal treatment over time. Juveniles in detritus treatments exhibited lower faecal production rates at the beginning of the experiment and after 75 days without significant differences in growth, suggesting the availability of high‐quality food in these treatments. This study provides key insights on husbandry conditions highly relevant to further develop S. cf. horrens aquaculture. [ABSTRACT FROM AUTHOR]

We have previously confirmed that β-integrin from Apostichopus japonicus (designated AjITGB) binds LPS and mediates the immune response. In this study, we found that AjITGB positively promoted the echinoderm immune cells located in the coelomic cavity (designated as coelomocyte) phagocytic activities. Flow cytometry assay indicated that the phagocytic percentage was significantly decreased, by a 37.3% and 41.36%, after AjITGB siRNA inference in vitro and in vivo , respectively, a result consistent with the decrease observed with an anti-AjITGB antibody blocking treatment. These decreased phagocytic activities were partially recovered by rAjITGB supplementation. To better understand the molecular mechanism underlying this phagocytosis, three phagocytic-related proteins, including Ajseptin2, Ajseptin7 and Ajseptin10, were cloned and further characterized. Completely consistent expression profiles were detected between AjITGB and Ajseptin2/7, at both the mRNA and protein levels, in V. splendidus -challenged sea cucumber. Furthermore, Ajseptin2/7 expression levels were significantly down-regulated in the AjITGB silencing group and could be partially recovered to its original level after rAjITGB administration. However, Ajseptin10 displayed no significant change in the same condition. A phagocytic assay further indicated that Ajseptin2/7, but not Ajseptin10, was crucial in mediating coelomocyte phagocytosis. The knockdown of the three genes by specific siRNAs indicated that Ajseptin2/7 significantly decreased coelomocyte phagocytosis, and this decrease was completely recovered after rAjITGB supplementation. There was no significant change in the phagocytosis rate in both the AjSEPT10 siRNA interference and rAjITGB supplementation groups. All our results confirmed that AjITGB modulates coelomocyte phagocytosis via the activation of Ajseptin2/7 but not AjSEPT10 and further supported the divergent roles of Ajseptins in AjITGB-mediated phagocytosis. [ABSTRACT FROM AUTHOR]

The density and population parameters of the sea cucumber Isostichopus badionotus from Sisal, Yucatan, Mexico were determined during the fishing season. Belt transects of 200 m2 were set in 10 sampling sites at two fishing areas. All organisms within the belt were counted and collected. In the harbor, 7,618 sea cucumbers were measured and weighed: the population parameters were determined using FISAT II. Mean densities of I. badionotus in April 2011, September 2011 and February 2012 were 0.84 ± 0.40, 0.51 ± 0.46, and 0.32 ± 0.17 ind m-2, respectively. Sea cucumber total length varied from 90 to 420 mm, with a uni-modal distribution. The growth parameters were: L∞ = 403 mm, K = 0.25, and to = -0.18, with an allometric growth (W = 2.81L1.781). The total mortality was 0.88, whereas natural mortality was 0.38, fish mortality was 0.50 and the exploitation rate 0.54. Even when sea cucumbers fishery in Sisal is recent and in development with a high density (5570 ind ha-1), it is necessary to establish management strategies to protect the resource, such as an annual catch quota, catching size (>280 mm length), monitoring of population density, and reproduction and larval distribution. [ABSTRACT FROM AUTHOR]

Using various chromatographic separations, three triterpene tetraglycosides (1-3), including one new compound, namely stichorrenoside E (1) along with thelenotoside B (2) and deacetyl thelenotoside B (3), were isolated from the MeOH extract of the Vietnamese sea cucumber Stichopus horrens. Their structures were confirmed by spectroscopic experiments, such as 1D and 2D NMR and HR-ESI-MS. Deacetylated thelenotoside B (3) is firstly isolated as a natural product. Among these compounds, thelenotoside B (2) showed strong cytotoxicities against five human cancer cell lines as HepG2, KB, LNCaP, MCF7 and SK-Mel2 with the IC50 values from 0.95 ± 0.08 to 1.90 ± 0.13 μM, whereas stichorrenoside E (1) and deacetyl thelenotoside B (3) exhibited significant activities with the IC50 values from 6.87 ± 0.25 to 11.62 ± 1.05 μM. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor (TNF)-α-induced protein 8 (TNFAIP8) family is a newly identified protein with vital roles in maintaining immune homeostasis. In the current study, we first cloned and characterized a TNFAIP8 gene from the invertebrate sea cucumber Apostichopus japonicus . The gene was designated as AjTNFAIP8 . The full-length cDNA of AjTNFAIP8 was 1455 bp long and encoded a matured protein of 201 amino acid residues. Structural analysis indicated that AjTNFAIP8 had a death effector domain (DED)-like domain and composed of six α-helices. Multiple sequence alignment and phylogenetic analysis supported that AjTNFAIP8 is a new member of the TNFAIP8 family. Analysis of basal transcription in five tissues revealed the constitutive expression of AjTNFAIP8 in the detected tissues with highest expression in the respiratory tree and minimum expression in the tentacle. Vibrio splendidus infection and LPS stimulation could significantly downregulate the mRNA expression of AjTNFAIP8 . More importantly, the transcription of pro-inflammatory molecule NOS and its production of NO content were significantly increased after AjTNFAIP8 silencing, with the suppression of agmatinase transcript and arginase activity. These results clearly indicated that AjTNFAIP8 is an essential negative regulator in innate immunity. Basic information for further exploration of the functional mechanisms of TNFAIP8 family in other marine invertebrate is provided. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to investigate the effects of dietary administration of synbiotic with Bacillus lincheniformis WS-2 (CGMCC No. 12813) and alginate oligosaccharides (AOS) on the growth, innate immune response, and intestinal microbiota of the sea cucumber Apostichopus japonicus and its resistance to Vibrio infection. Sea cucumbers were given a control diet (non-supplemented), pro diet (basal diet plus 1 × 10 9 cfu (g diet) −1 B. lincheniformis WS-2), syn diet (basal diet plus 1 × 10 9 cfu (g diet) −1 B. lincheniformis WS-2 and 10 g (kg diet) −1 AOS) or pre diet (basal diet plus 10 g (kg diet) −1 AOS) over a period of 60 days, and the growth performance and various innate immune parameters of the animals were evaluated after 30 and 60 days of feeding. No significant difference in growth performance was observed between the group fed with the syn and the group fed with the pro diet, but both these groups exhibited significant (P < 0.05) enhancement in growth performance compared to the control group. At the same time, both syn and pro diets also resulted in the animals having significantly higher levels of amylase, protease and alginate lyase activities compared to the con diet. Individuals fed with the syn or pro diet showed enhanced levels of various immune enzyme activities, compared to those fed with the con diet. At the end of the growth period, the sea cucumbers were challenged with Vibrio splendidus via intraperitoneal injection. The survival rates of sea cucumbers fed with the syn, pro or pre diet were significantly improved compared to that of sea cucumbers fed with the con diet, with sea cucumbers fed with synbiotic having the highest survival. In addition, increased proportions of Bacillus and Lactococcus were found in the intestinal tract of sea cucumbers fed with the syn diet (9.5% and 7.3%) compared to those of sea cucumbers fed with the pro diet (6.1% and 4.6%), con diet (4.0% and 3.4%), or pre diet (5.2% and 6.8%) after 60 days of feeding. Furthermore, the proportion of Vibrio in the intestinal tracts of sea cucumbers fed with the pro diet (2%) or syn diet (3.1%) was lower than that of sea cucumbers fed with the con diet (5.5%) or pre diet (3.8%), although no significant difference was detected between the pro diet and syn diet groups ( P > 0.05). Overall, the results suggested that dietary synbiotic consisting of Bacillus lincheniformis and alginate oligosaccharides (AOS) could have positive benefit for sea cucumber aquaculture. [ABSTRACT FROM AUTHOR]

Inflammatory/defensive response after pathogen invasion is considered a local defense reaction in vertebrates. Inflammation response in Apostichopus japonicus was hardly determined due to scarce information available for nucleotide binding domain-like receptor family, pyrin domain-containing (NLRP) family. In the present study, invertebrate NLRP homologue was identified from A. japonicus (designated as AjNLRP3-like ) by rapid amplification of cDNA ends. Full-length cDNA of AjNLRP3-like measured 2970 bp with 2265 bp open reading frame encoding a 754-amino acid (aa) residue protein. Structural analysis revealed that AjNLRP3-like processed characteristic domains of pyrin (32–102aa) and NACHT (183–339aa). Multiple sequence alignment and phylogenetic analysis supported that AjNLRP3-like belongs to a new member of NLRP3 protein subfamily. Spatial expression analysis revealed that AjNLRP3-like was ubiquitously expressed in all examined tissues with larger magnitude in coelomocytes. Both Vibrio splendidus challenge in vivo and lipopolysaccharide stimulation in vitro significantly upregulated mRNA expression of AjNLRP3-like when compared with the control group. NLRP3-mediated inflammation response depended on release of lysosomal cathepsin B (CTSB) and subsequent activation of high-mobility group box (HMGB) in vertebrates. We investigated expression profiles of AjNLRP3-like and AjHMGB after AjCTSB knock-down and discovered that AjNLRP3-like was depressed by 0.66-fold and 0.47-fold, whereas AjHMGB was depressed by 0.70-fold and 0.50-fold at 24 and 48 h in AjCTSB -silenced group, respectively. Similarly, down-regulation of AjHMGB was also observed after AjNLRP3-like knock-down. This study therefore suggests that A. japonicus feature similar inflammatory events as those in vertebrates, and activation of AjNLRP3-like depends on AjCTSB expression and release of AjHMGB . [ABSTRACT FROM AUTHOR]

Using various chromatographic separation techniques, eight triterpene diglycosides ( 1 – 8 ), including four new compounds namely stichorrenosides A–D ( 1 – 4 ), were isolated from a methanol extract of the Vietnamese sea cucumber S. horrens . Their structures were elucidated based on spectroscopic analyses, including HR ESI MS, 1D and 2D NMR. Their in vitro cytotoxic activity against five human cancer cell lines, Hep-G2 (hepatoma cancer), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma), was evaluated using SRB methods. Stichorrenoside D ( 4 ), stichoposide A ( 5 ), and 3 β - O -[ β - d -xylopyranosyl-(1→2)- β - d -xylopyranosyl]-23 S -acetoxyholost-7-ene ( 7 ) showed strong cytotoxicity on all five tested cancer cell lines, whereas significant effect was observed for stichorrenoside C ( 3 ) and stichoposide B ( 6 ). [ABSTRACT FROM AUTHOR]

Alpha-2-macroglobulin ( A2M) is essential for hosts defending against pathogen infections. In this study, two distinct A2Ms were identified from sea cucumbers Stichopus monotuberculatus and Holothuria atra, which belong to different genera in the Phylum Echinodermata, and named StmA2M and HaA2M, respectively. Structural analysis of StmA2M and HaA2M revealed that all contain the bait region domain, thioester domain, and receptor-binding domain. Phylogenetic analysis indicated that StmA2M and HaA2M all belong to the echinoderm A2Ms. The cleavage site RXXR and the catalytic histidine residue for complement component C3 were found in StmA2M and HaA2M. Compared with human A2M, the three-dimensional structures of StmA2M and HaA2M were more similar to that of common carp A2M. Both StmA2M and HaA2M showed the strongest response at transcriptional levels to lipopolysaccharide ( LPS) at 12 h and polyriboinosinic polyribocytidylic acid [Poly (I: C)] at 24 h, respectively. Activity of StmA2M showed the strongest response to Poly (I: C) at 6 h, while the strongest change of HaA2M activity was induced by LPS at 24 h. The differential mRNA expression and enzyme activity levels suggested that A2M in sea cucumbers might be involved in different immune responses to LPS or Poly (I: C) challenge. [ABSTRACT FROM AUTHOR]

Apostichopus japonicus is one of the main aquaculture species in northern China. The green tide macroalgae Chaetomorpha linum and the seagrass Zostera marina occur in this region. Our previous study has suggested that Z. marina detritus can be a food source for A. japonicus . In the present study, we carried out a laboratory simulation experiment for 60 days to understand whether C. linum can also be utilized to fulfill the nutrient demands of A. japonicus . The powdered C. linum and Z. marina detritus, mixed in five ratios (100:0; 75:25; 50:50; 25:75; 0:100), were fed to sea cucumbers along with muddy sediment in a fixed proportion. Sargassum thunbergii (40%) combined with the muddy sediment (60%) was also used as a standard reference/control diet. Results showed that the specific growth rates (SGRs), food utilizing efficiencies and energy budgets of A. japonicus were strongly influenced by the ratio of C. linum and Z. marina in their diets. The growth energy deposited in the bodies of sea cucumbers fed higher proportions of C. linum was significantly higher than those fed higher proportions of Z. marina . Furthermore, sea cucumbers fed on C. linum and S. thunbergii had similar growth performances. This study indicated that C. linum could replace S. thunbergii as a food source for A. japonicus . Statement of relevance Because of its high nutritive and medical properties, the sea cucumber Apostichopus japonicus has become a highly valuable fishery and aquaculture species in Asia. Influenced by eutrophication in coastal waters, blooming events of the green tide algae Chaetomorpha linum are increasing around the world, including some natural habitats for A. japonicus in northern China. However, whether C. linum can also be utilized to fulfill the nutrient demands of sea cucumbers, such as A. japonicus , is unknown. We carried out a laboratory simulation experiment for 60 days to study this question. Our results showed that sea cucumbers fed on C. linum and Sargassum thunbergii had similar performances. Due to its higher protein and lower cellulose contents, C. linum was easier for A. japonicus to digest and absorb, and more energy per unit of food was converted to growth. This study indicated that C. linum could act as a food source for A. japonicus . The results of this research are also beneficial for promoting the collection and control of C. linum . [ABSTRACT FROM AUTHOR]

A feeding trial aimed to determine the effects of dietary lipid level on growth performance, body composition and digestive enzymes activity of juvenile sea cucumber, Apostichopus japonicus. Diets with six crude lipid levels (1.9, 13.8, 29.1, 43.6, 59.6 and 71.6 g kg−1) were fed to sea cucumbers (initial weights 0.65 ± 0.01 g) at a density of 30 juveniles, once a day. After 60 days, body weight gain ( BWG), specific growth rate ( SGR), feed intake ( FI) and protein efficiency ratio ( PER) decreased with increasing dietary lipid levels. The sea cucumbers fed 1.9 g kg−1 crude lipid showed significantly higher ( P < 0.05) BWG than those of the sea cucumbers fed 59.6 and 71.6 g kg−1 crude lipid. Intestinal protease and lipase activities generally increased with increasing dietary lipid levels. Eicosapentaenoic acid ( EPA) content of body walls generally increased with increasing dietary lipid levels. Docosahexaenoic acid ( DHA) content of body walls reached the maximum value at a dietary lipid level of 13.8 g kg−1. N-3 highly unsaturated fatty acid content followed the same pattern of DHA. According to the growth performance and body composition of sea cucumbers, it can be indicated that the optimum dietary lipid level for juvenile sea cucumbers is between 1.9 and 13.8 g kg−1. [ABSTRACT FROM AUTHOR]

The organics-degrading bacteria were isolated from sea cucumber ( Apostichopus japonicus) outdoor rearing ponds sediment. The bacterial strains were selected according to the isolation growth, pathogenicity, organic degradation rate, and effects on A. japonicus growth and water quality. The screened strains were identified on physiological, biochemical, and genetic characteristics. Among 68 strains isolated, two strains (L15 and E4) were identified as potential organics-degrading probiotics. The degradation rates on sediment chemical oxygen demand (COD) were 46.95 ± 1.58 % for the L15 strain and 44.31 ± 1.44 % for the E4 strain. The L15 strain enhanced the specific growth rate (SGR) of A. japonicus by 1.97 ± 0.49 %, and the E4 strain enhanced SGR by 2.24 ± 0.44 % compared with the SGR of 0.55 ± 0.41 % in the control group without probiotics. The COD level increased by −0.9 ± 1.42 % of L15 and 47.9 ± 0.06 % of E4 inoculations after 7 days, while the COD increased by 140.6 ± 4.22 % in the control. Based on the analyses of biochemical characteristics and 16S rRNA gene sequences, the L15 and E4 strains were identified as Bacillus spp. and Pseudomonas spp., respectively. [ABSTRACT FROM AUTHOR]

The forkhead box O (Foxo) transcription factors are involved in multiple signaling pathways and play key roles in immunoregulation in vertebrates. In the present study, we firstly identified a novel Foxo gene in Apostichopus japonicus coelomocytes using transcriptome sequencing and RACE approaches (denoted as AjFoxo). The full-length cDNA of AjFoxo was of 2248 bp with a 5′ untranslated region (UTR) of 177 bp, a 3′ UTR of 367 bp and an ORF of 1704 bp encoding a polypeptide of 567 amino acid residues. The highly conserved forkhead domain was also identified in AjFoxo with remarkably higher degree of structural conservation. AjFoxo transcripts could be detected in all examined tissues with predominant expression in the coelomocytes and muscle, and slightly weak in the tissues of tentacle, intestine and respiratory trees. Concerning the time-course expression of AjFoxo in coelomocytes, the relative expression of AjFoxo was dramatically decreased to 0.44-fold at 48 h compared with that in the control group after Vibrio splendidus challenge, which was consistent with that of AjIκB. RNA interference of AjFoxo in primary coelomocytes also significantly depressed the relative expression of AjIκB with a 0.37-fold decrease compared with control group. Taken together, these results indicated that AjFoxo was a novel immune regulator and might be involved in the processes of anti-bacteria response in sea cucumber through activating the transcription of AjIκB. [ABSTRACT FROM AUTHOR]

The effects of dietary addition of yeast Rhodotorula benthica ( R. benthica ) D30 which isolated from local sea mud at levels of 0 (control), 10 5 , 10 6 and 10 7 CFU/g feed on the growth performance, digestive enzyme activity, immunity and disease resistance of juvenile sea cucumber Apostichopus japonicus were investigated. It was shown that dietary addition of R. benthica D30 significantly increased the growth rates of sea cucumbers ( p < 0.05). The amylase activity, cellulase activity and alginase activity were increased for the animals from three probiotics treated groups. And with the supplemented concentration increased, the values of those digestive enzyme activities increased as well. Dietary addition of R. benthica D30 at the level of 10 7 CFU significantly increased the lysozyme, phagocytic and total nitric oxide synthase activity of A. japonicus ( p < 0.05). While, the highest values of the phenoloxidase and alkaline phosphatase activity were found in sea cucumbers fed with R. benthica D30 at the level of 10 6 CFU. Whereas adding R. benthica D30 to diet had no significant effects on the total coelomocyte counts and acid phosphatase activity of A. japonicus ( p > 0.05). It was observed that adding R. benthica D30 could significantly decrease the cumulative mortality of sea cucumbers. The present study demonstrated that dietary addition of R. benthica D30 could increase growth performance and some digestive enzyme activities, improve immunity and disease resistance of A. japonicus . And the medium (10 6 CFU) and high (10 7 CFU) additional levels showed better effects. It suggests that yeast R. benthica D30 could be a good probiotic for aquaculture. [ABSTRACT FROM AUTHOR]

Abstract: Ferritin is one of the major non-harm iron storage proteins that found in most cell types of animals, plants and microorganisms. In this study, a ferritin subunit named StmFer was identified from the sea cucumber (Stichopus monotuberculatus) and characterized functionally. The full-length cDNA of StmFer is 1184 bp in size with a 5′-untranslated region (UTR) of 131 bp, a 3′-UTR of 531 bp and an open reading frame of 522 bp that encoding a protein of 173 amino acids with a deduced molecular weight of 19.95 kDa. StmFer possesses both the ferroxidase center of vertebrate ferritin heavy subunit and iron nucleation sites of vertebrate ferritin light subunit. For the gene structure, StmFer contains only three exons separated by two introns. Higher levels of mRNA expression were noticed in intestine and coelomocyte of S. monotuberculatus by northern blot analysis. In in vitro experiments performed in coelomocytes, transcriptional expression of StmFer showed the strongest response to polyriboinosinic polyribocytidylic acid [Poly (I:C)] (9.08 fold up-regulation), followed by lipopolysaccharides (LPS), ferrous chloride (FeCl2) and inactivated bacteria (Vibrio alginolyticus) (7.84, 7.41 and 4.90 fold up-regulation, respectively) after 3 h post-challenge. In addition, the anti-oxidation activity and iron binding capacity of recombinant ferritin protein were demonstrated in this study. As a whole, our study suggested that the ferritin from sea cucumber may play critical roles not only in the cellular and organismic iron homeostasis, but also in the innate immune defense. [Copyright &y& Elsevier]

Stichopus ocellatus , known as eye-spotted sea cucumber, is a commercially important Stichopodidae holothuroid in Indo-Pacific region for its valuable nutrition and medicinal ingredients. However, because the taxonomic analyses based on morphological characters and molecular data within Aspidochirotida are limited, the deep-level evolutionary relationships of Aspidochirotida are still poorly understood. Here, for providing better insight of future evolutionary and taxonomic classification of Stichopodidae, we report the first complete mitogenome of S. ocellatus along with 37 annotated and characterized mitochondrial genes, and the phylogenetic analysis based on mitogenome data reveals sister relationship between S. ocellatus and S. monotuberculatus ., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

The complete sequence of mitochondrial DNA (mt DNA) from Stichopus sp. (Echinodermata: Holothuroidea: Stichopodidae: Stichopus) was acquired using conventional PCR and long PCR followed by cloning and sequencing. The mt DNA is a circular molecule of 16 257 bp in length, containing the set of 37 genes, including 13 protein-coding genes ( PCGs), 22 t RNA genes and two ribosomal RNA genes. The plus strand consists of 30.9% A, 23.7% C, 16.0% G and 29.3% T bases (AT skew = 0.027; GC skew = −0.194). All 13 PCGs encode a total of 3782 amino acids and all 22 t RNA genes were predicted to be capable of folding into a clover-leaf secondary structure. Intergenetic regions in the mitochondrial genome of Stichopus sp. contain 903 bp in total, with the largest continuous region (674 bp, AT% = 58.6) between t RNA-Thr and t RNA-Pro. Analysis of phylogenetic relationship of family Stichopodidae and genetic distances (species among the family Stichopodidae and species within Stichopus monotuberculatus group) based on the partial cox1 sequence demonstrates that Stichopus sp. from the South China Sea is a member of S. monotuberculatus complex. [ABSTRACT FROM AUTHOR]

The brown sea cucumber fishery is active in the Galapagos Islands since the year 1991 after its collapse in mainland Ecuador. This paper analyzes the Galapagos Sea cucumber fishery over the past decade and the reasons for its management pitfalls and chronic over fishing, and proposes an improved strategy for estimating stock size and harvest potential. Based on the historical distribution of the fishing fleet and past fishery surveys, 15 macrozones were defined; their areas were estimated from the coastline to the 30m isobaths and the numbers of sample replicates per macrozone were calculated for a density estimate precision of ±25%. Overall stock size was calculated by summing over all macrozones and was multiplied by 0.122 to obtain the annual quota. This multiplier was derived by inserting an exploitation rate of E=0.3 and a published natural mortality value of M=0.17 into Cadimas formula, thereby obtaining a more conservative precautionary quota estimate. Pre-fishery stock densities in 2009 were below the legal threshold value and the fishery remained closed. Mean densities were significantly lower in the deeper (>15m) than in the shallower (<15m) stratum, contrary to fishermen expectations. Through an empirical regression of (log) pre-fishery density versus subsequent annual catch for the period 1998-2008 we found that catches of most years greatly exceeded the here proposed quota explaining the collapsed nature of the stock. [ABSTRACT FROM AUTHOR]

Stichopus hermanni and Stichopus vastus are sea cucumber species from the Stichopodidae family within the coastal waters of Malaysia. The integument of these invertebrates is hypothesised to contain abundant glycosaminoglycans (GAGs). GAGs are divided into non-sulphated and sulphated GAGs. Sulphated GAGs have various chemico-biological functions that are beneficial to humans. This study quantitatively analysed N-, O-sulphated and total sulphated GAG content from three different anatomical regions (integument, internal organs and coelomic fluid) of S. hermanni and S. vastus. The integument revealed the highest content of total, O- and N-sulphated GAGs, followed by the internal organs and the coelomic fluid for both species of sea cucumbers. The percentage division of O- and N-sulphated GAGs suggested that anatomical parts of both species showed higher levels of O-sulphated GAGs compared to N-sulphated GAGs. In conclusion, these findings indicate that the integument body wall of S. hermanni and S. vastus is a rich source of sulphated GAGs. [ABSTRACT FROM AUTHOR]

Abstract: The Stichopodidae comprise a diverse assemblage of holothuroids most of which occur in the Indo-Pacific. Phylogenetic analyses of mitochondrial gene (COI, 16S rRNA) sequence for 111 individuals (7 genera, 17 species) clarified taxonomic uncertainties, species relationships, biogeography and evolution of the family. A monophyly of the genus Stichopus was supported with the exception of Stichopus ellipes. Molecular analyses confirmed genus level taxonomy based on morphology. Most specimens harvested as S. horrens fell in the S. monotuberculatus clade, a morphologically variable assemblage with others from the S. naso clade. Taxonomic clarification of species fished as S. horrens will assist conservation measures. Evolutionary rates based on comparison of sequence from trans-ithmian Isostichopus species estimated that Stichopus and Isostichopus diverged ca. 5.5–10.7Ma (Miocene). More recent splits were estimated to be younger than 1Ma. [Copyright &y& Elsevier]

Abstract: Stichopus regalis is a common sea cucumber that is found in a wide depth range in the Mediterranean beyond 50m depth. Its five longitudinal muscular bands are a culinary delicacy. It is the most expensive seafood product on the Catalan market, and it can reach up to 130€/kg. Despite its ecological and economical importance, information related to this species is very scarce. The population inhabiting the Mallorca and Menorca continental shelf and slope was studied using data from several different surveys conducted from 2001 to 2009. The spatial distribution of the royal cucumber is strongly aggregated. The population showed a multimodal length-frequency distribution, with individuals ranging from 65 to 295mm in length. Abundance was highest between 100 and 299m depth and sizes were largest between 50 and 299m depth. The length–weight relationship indicates a negative allometry, explained by the fact that the thickness of some parts of the body wall appears to be independent of the size of the individual. Although S. regalis has a high price, due to its relatively low abundance it is not a particular target species of the multispecies trawl fisheries, and is captured as a by-catch, with a mean catch per unit effort of 1.78kg per boat and day. The edible part corresponds to 9.81% of the drained weight of the whole animal. [Copyright &y& Elsevier]

Abstract: Sea cucumbers are traditional, delicious and luxurious seafood in Asia. They are usually provided to the consumers in the marketing formats of dried or frozen products. At the commercial level, they are much different not only in flavor, but also in price. The processing treatment makes them difficult for species identification based on morphological characterization. In this study, two molecular methods are developed to identify six species belonging to family Stichopodidae in commercial products. The first one is PCR–RFLP (polymerase chain reaction–restriction fragment length polymorphism), which uses PCR amplification of a common 570bp fragment of the 16S rRNA gene and follows codigestion with two restriction enzymes (XmnI and MwoI). Another one is FINS (forensically informative nucleotide sequencing) of the 16S rRNA gene, and the key of the method is the phylogenetic analysis of 16S rRNA gene sequences. The PCR–RFLP methodology can be used to authenticate the species tested in the present study and allow us to detect a fraudulent labeling of frozen Apostichopus japonicus product. And the FINS methodology confirms that the species substituted for A. japonicus belongs to the genera Isostichopus. Therefore, two molecular tools really provide convenient, useful and academic techniques to authenticate the species of commercial sea cucumber products. [Copyright &y& Elsevier]

It has been suggested that the Japanese sea cucumber, Apostichopus japonicus, has three color types (red, green, and black), although the qualitative difference between the color types, particularly between the green and black types, is unclear because of continuous color variation among color types. This study elucidated the color variation between green and black types using image processing (RGB, red–green–blue system) and multivariate analysis to demonstrate whether or not the black and green types can be quantitatively classified. Moreover, spatial variation of the RGB value among various local sites was clarified to estimate potential environmental factors that may affect the color variation. The series of analyses revealed that a quantitative boundary between green and black types could be provisionally established, and also that spatial variability in the intermediate (continuous) color trait between green and black types was significant. Potential environmental factors (depth and industrial activity index) were correlated with the color traits in both color types. These results suggest that the green and black types cannot be regarded as independent color traits and that the color variation between green and black types may be influenced by local environmental factors. [ABSTRACT FROM AUTHOR]

To examine the distribution pattern of adult Apostichopus japonicus, approximately monthly surveys were conducted during a 2-year period in the subtidal zone of a harbor area in Yoshimi Bay, western Yamaguchi Prefecture. Results showed a clear seasonal change in distribution pattern: many animals were distributed on the seabed and the lower part of a jetty during winter to spring, whereas most animals occurred on the upper part of a jetty during summer to autumn, namely, the aestivation season. Such change is considered to be due to the migration of animals within the present study site. [ABSTRACT FROM AUTHOR]

The material collected by the G.O. Sars MAR-ECO expedition to the Mid-Atlantic Ridge included 36 species of holothurians. Most belong to the order Elasipodida and the family Synallactidae (Aspidochirotida). Four species in the families Elpidiidae and Psychropotidae (Elasipodida) are new to science. Descriptions of Benthodytes gosarsi sp. nov., Penilpidia midatlantica sp. nov., Peniagone longipapillata sp. nov. and Peniagone marecoi sp. nov. are provided, along with the full list of identified species. Some descriptions are supplemented by observations in situ from dives of the Mir submersibles. [ABSTRACT FROM AUTHOR]