Cultured Sea Cucumbers Research Articles

The effect of temperature and sand substrate in tanks on the growth and survival of the warty sea cucumber Neostichopus grammatus

ABSTRACT Water temperature and the presence of sand substrate are considered critical environmental factors affecting the growth of cultured sea cucumbers. This study investigated the effects of water temperatures and the presence or absence of sand substrate in tanks on the growth of N. grammatus fed an equal ration of abalone waste for eight weeks. Sea cucumbers with a mean weight of 8.34 g were used for the study. The treatments used in the study were Ambient water temperature + sand (A + S), Ambient water temperature without sand (A-S), Cold water temperature + sand (C + S), and Cold-water temperature without sand (C–S). The cold/constant water temperature was 16°C and was representative of winter conditions while the ambient/fluctuating water temperature fluctuated between 16.4 and 18.7 °C and was representative of spring conditions. At the end of the study, the sea cucumbers in A + S and C + S treatment groups exhibited an overall weight increase of 21.08% and 6.18%, respectively. The sea cucumbers reared in ambient water temperature exhibited significantly higher mean weight than those reared in cold water (F 1, 66 = 5.69; p = 0.02), and sea cucumbers reared with sand substrate had significantly higher mean weight compared to those without sand substrate (F 1,66 = 19.06; p = <0.001). This study has shown that growth rates of N. grammatus in tanks were higher in ambient temperatures and that stress was reduced in the presence of sand, a habitat that mimics its natural environment. This implies that sand substrate may be necessary for the farming of N. grammatus.

YTHDC1/CRM1 Facilitates m6A-Modified circRNA388 Nuclear Export to Induce Coelomocyte Autophagy via the miR-2008/ULK Axis in Apostichopus japonicus.

N 6-methyladenosine (m6A), the most prevalent internal modification in eukaryotic RNA, was able to mediate circular RNA (circRNA) function in many immune processes. Nevertheless, the functional role of m6A-modified circRNAs in innate immunity of invertebrates remained unclear. In this study, we identified m6A-modified circRNA388 from cultured sea cucumber (Apostichopus japonicus) coelomocytes, which was mainly detected in cytoplasm after Vibrio splendidus infection. A knockdown assay indicated that cytoplasm circRNA388 promoted coelomocyte autophagy and decreased the number of intracellular V. splendidus. Mechanistically, the circRNA388 in the cytoplasm directly sponged miR-2008 to block its interaction with Unc-51-like kinase 1 from A. japonicus (AjULK) and further promoted autophagy to resist V. splendidus infection. More importantly, we found that m6A modification was vital to circRNA388 nuclear export with YTH domain-containing protein 1 from A. japonicus (AjYTHDC1) as the reader. AjYTHDC1 facilitated the nuclear export of m6A-modified circRNA388 via interaction with exportin-1 (chromosomal maintenance 1) from A. japonicus (AjCRM1). Knockdown of AjCRM1 could significantly decrease the content of cytoplasm circRNA388. Overall, our results provide the first evidence that nuclear export of m6A-modified circRNA388 is dependent on the novel AjCRM1 to our knowledge, which was further promoted coelomocyte autophagy by miR-2008/AjULK axis to clear intracellular V. splendidus.

Characterization of microbiota and histology of cultured sea cucumber Isostichopus badionotus juveniles during an outbreak of skin ulceration syndrome.

Due to the dramatic reduction of sea cucumber Isostichopus badionotus populations in the Yucatan Peninsula by overfishing and poaching, aquaculture has been encouraged as an alternative to commercial catching and restoring wild populations. However, the scarcity of broodstock, the emergence of a new disease in the auricularia larvae stage, and the development of skin ulceration syndrome (SUS) in the culture have limited aquaculture development. This study presents the changes in the intestine and skin microbiota observed in early and advanced stages of SUS disease in cultured juvenile I. badionotus obtained during an outbreak in experimental culture through 16S rRNA gene sequencing and histological evidence. Our results showed inflammation in the intestines of juveniles at both stages of SUS. However, more severe tissue damage and the presence of bacterial clusters were detected only in the advanced stages of SUS. Differences in the composition and structure of the intestinal and skin bacterial community from early and advanced stages of SUS were detected, with more evident changes in the intestinal microbial communities. These findings suggest that SUS was not induced by a single pathogenic bacterium. Nevertheless, a decrease in the abundance of Vibrio and an increase in Halarcobacter (syn. Arcobacter) was observed, suggesting that these two bacterial groups could be keystone genera involved in SUS disease.

Artificial Reefs Reduce Morbidity and Mortality of Small Cultured Sea Cucumbers Apostichopus japonicus at High Temperature

Summer mortality and morbidity are serious environment-related problems in cultured sea cucumbers (Apostichopus japonicus). Air exposure probably worsens the impact of high temperature on cultured sea cucumbers. In this present study, two laboratory experiments were designed to investigate the effects of artificial reefs on mortality, morbidity, crawling, feeding, and adhesion behaviors of small sea cucumbers (~1 g of wet body weight) after air exposure and disease outbreaks at 25 °C, respectively. Significantly lower mortality and morbidity occurred in the group with artificial reefs compared with those in the group without artificial reefs in the two experiments. This present study found that the stressed sea cucumbers cultured inside artificial reefs showed a significantly higher adhesion index, feeding behavior, and crawling frequency than those cultured without artificial reefs. In disease challenge assays, small sea cucumbers cultured inside the artificial reefs showed a significantly higher adhesion index and crawling frequency than those cultured without artificial reefs at 25 °C. Feeding, crawling, and adhesion behaviors of sea cucumbers cultured outside artificial reefs were not significantly different from those cultured without artificial reefs. The experimental results indicate that sea cucumbers with good fitness-related behaviors may be less affected by the disease and more likely to move into the crevices of artificial reefs. Fitness-related behaviors were poor in sea cucumbers cultured outside artificial reefs, so we considered them as affected individuals. Thus, artificial reefs provide a place to reduce the physical contact between unaffected and diseased/affected individuals, showing a potential to reduce disease transmission. Our present study establishes a cost-effective approach to increasing the survival of small sea cucumbers in seed production at high temperatures.

The Phospholipid Molecular Species Profile of Apostichopus japonicus Tissues Modifies through Exposure to n-3 Polyunsaturated Fatty Acid-Deficient Diet.

The sea cucumber Apostichopus japonicus, being a target species of commercial fisheries and aquaculture, is also used as a source of biologically active compounds with high pharmacological potential. By the methods of high-performance liquid chromatography with high resolution mass spectrometry, we analyzed the major structural phospholipids (PL)—glycerophosphoethanolamines (PE), glycerophosphocholines (PC), glycerophosphoserines (PS), and glycerophosphoinositols (PI)—in tissues of wild and cultured sea cucumbers. The intestines of the wild and cultured animals differed from the other tissues by an elevated content of molecular species of PE, PC, and PS with 22:6n-3 fatty acid. The respiratory trees of the studied animals contained a high level of odd-chain PI and PI with 20:4n-6. The exposure to n-3 PUFA-deficient diet resulted in substantial changes in the molecular species profile of PL of the wild and cultured animals. The cultured sea cucumbers showed a significant decrease in the 20:5n-3 content in all four studied PL classes. A replacement of 20:5n-3 by 20:4n-6 occurred in PE, PC, and PI. The decrease in the level of molecular species of PS with 20:5n-3 was compensated by an increase in the level of monounsaturated long-chain PS. The diet of cultured sea cucumbers is a crucial factor for enhancing the nutritional properties of the product obtained from them.

Determination of sulfonamide residues in cultured sea cucumber by pre-column derivatization capillary electrophoresis with fluorescence detection

A simple and mild method for the separation of sulfonamide residues based on a condensation reaction with O-phthalaldehyde solution (OPA) as labeling reagent with capillary electrophoresis has been developed. A 58.5 cm × 50 μm i.d. (50 cm effective length) untreated fused-silica capillary was used. To optimize the separation conditions, the background electrolyte concentration, pH, column temperature, voltage and other factors were evaluated. The optimal separation conditions were as follows: 20 mmol L−1 borate buffer; pH 9.1; column temperature 20 °C; separation voltage 18 kV, pressure 50 mbar and injection time 8 s. Under the optimal conditions, 10 kinds of sulfonamide derivatives could be well-separated within 8 min, and the linear ranges were 0.35–100 μg kg−1. The detection limit (at a signal-to-noise ratio of 3) was in the range of 0.12–0.25 μg kg−1, and the quantification limit (at a signal-to-noise ratio of 10) was in the range of 0.35–0.70 μg kg−1. The sulfonamide residues from cultured sea cucumber samples were determined under the optimal conditions with satisfactory results.

Exploiting the gut microbiota to predict the origins and quality traits of cultured sea cucumbers.

Nowadays, the true economic and nutritional value of food is underpinned by both origin and quality traits, more often expressed as increased quality benefits derived from the origin source. Gut microbiota contribute to food metabolism and host health, therefore, it may be suitable as a qualifying indicator of origin and quality of economic species. Here, we investigated relationships between the gut microbiota of the sea cucumber (Apostichopus japonicus), a valuable aquaculture species in Asia, with their origins and quality metrics. Based on data from 287 intestinal samples, we generated the first biogeographical patterns for A. japonicus gut microbiota from origins across China. Importantly, A. japonicus origins were predicted using the random forest model that was constructed using 20 key gut bacterial genera, with 97.6% accuracy. Furthermore, quality traits such as saponin, fat and taurine were also successfully predicted by random forest models based on gut microbiota, with approximately 80% consistency between predicted and true values. We showed that substantial variations existed in the gut microbiota and quality variables in A. japonicus across different origins, and we also demonstrated the great potential of gut microbiota to track A. japonicus origins and predict their quality traits.

Isolation and characterization of Vibrio alginolyticus strain HAT3 causing skin ulceration disease in cultured sea cucumber Holothuria atra (Jaeger, 1833)

Skin ulceration disease is widespread among aquacultured holothuroids. Herein, we report on the skin ulceration disease of juvenile Holothuria atra reared in the Aquaculture Laboratory of the National Institute of Oceanography and Fisheries in Hurghada, Red Sea, Egypt. The disease caused the death of the animals within 3 days, and the signs included depigmentation of the epidermis, visceral ejection, and autolysis of the body. The dominant bacterial isolate obtained from the individuals with lesions on the skin was labelled as HAT3, and was selected for characterization and disease induction assay. Based on the morphological and biochemical characteristics, and 16s rDNA gene sequence analysis, the isolate HAT3 was identified as a strain of Vibrio alginolyticus and designated as V. alginolyticus strain HAT3. The 16s rDNA gene sequence was deposited in the GenBank under the accession number MW546612. The experimental infection of healthy H. atra with V. alginolyticus strain HAT3 induced the disease with the same signs as the naturally infected H. atra. Our results revealed that V. alginolyticus strain HAT3 was the causative pathogen of skin ulceration disease in reared H. atra.

Differences in lipid class and fatty acid composition between wild and cultured sea cucumbers, Apostichopus japonicus , explain modification and deposition of lipids

The Japanese sea cucumber Apostichopus japonicus, a commercial species highly valued for its medicinal and nutritious properties, is wild-harvested cultured in the countries of the North Pacific region. To assess the modification and deposition of dietary lipids in tissues of A. japonicus, the compositions of lipid classes and fatty acids (FAs) in the body wall and alimentary canal were compared between wild and cultured specimens. The results show that dietary lipids are rich in iso/anteiso saturated FAs (SFAs), monounsaturated FAs (MUFAs; mainly, 18:1n-9 and 18:1n-7) and linoleic acid (18:2n-6). A deficiency in dietary polyunsaturated FAs (PUFAs) considerably reduces the total and storage lipids in the alimentary canal, modifies the FA composition of both tissues, and increases the difference in the FA profile between the body wall and alimentary canal. Cultured specimens have trace amounts of 16:1n-7, a considerably higher level of 20:4n-6 and a lower level of 20:5n-3 compared with those recorded from wild animals. A suggestion is made that dietary SFAs are not deposited, whereas dietary C16 PUFAs and 20:5n-3 are accumulated. Dietary C16-18 MUFAs are rapidly elongated into C22-24 MUFAs, and dietary 18:2n-6 is converted into 20:4n-6. Knowledge of these patterns may facilitate a choice between available diets to optimize the lipid profile of cultured sea cucumbers.

Assessment of the Nutritional Value of Cultured Sea Cucumber Apostichopus japonicus

ABSTRACT The sea cucumber (Apostichopus japonicus) is a high-priced and appreciated food. Output of cultured sea cucumber has been increasing in China. From a nutritional point of view, there is still limited data on the chemical composition of cultured sea cucumber from pond and cage aquaculture. Therefore, the nutritional value of sea cucumber from 4 important aquaculture regions of Dalian, Yantai, Qingdao, and Putai in China were evaluated in the present work. The proximate composition, except for protein, and the profiles of amino acid and fatty acid were significantly different among the aquaculture regions, especially, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). The cultured sea cucumbers were rich in glutamine (66.90–71.60 g kg−1), glycine (54.30–58.90 g kg−1), and leucine (29.20–32.40 g kg−1) and showed a high content in PUFA (35.26%–46.47%), especially eicosapentaenoic (EPA, 10.04%–16.04%). All cultured sea cucumber have the recommended essential amino acid/total amino acid (0.33–0.35), lysine/arginine (0.66–0.74), and n-6/n-3 ratio (0.52–1.88) for good health status of humans and very low level of atherogenic and thrombogenic indices (0.20–0.36 and 0.21–0.29, respectively). The results indicate that the cultured sea cucumber has a nutritional value perfectly compatible with nutritious and healthy diets

Evaluation of the growth and survival rate of the Caribbean Sea cucumber, Isostichopus badionotus (Selenka, 1867), early juveniles produced in captivity

Isostichopus badionotus is a new commercially important sea cucumber in the Caribbean that has rapidly shown signs of overexploitation. There is no information on the growth and survival rates for wild or hatchery‐produced early juveniles. Hatchery production and determination of juvenile growth rates are essential for future aquaculture efforts for this species. In this study, daily growth rate (GR), specific growth rate (SGR), weight gain (WG), survival rate (SR), and weight–length relation (WLR) were evaluated using small (0.01 g) and large (0.25 g) hatchery‐produced early juveniles under laboratory conditions. Growth was rapid compared to other cultured sea cucumber species; maximal values of SGR and WG were obtained for small juveniles (4.58%/day and 2,191%, respectively), while maximal GR and SR were obtained for large juveniles (0.29 mm/day and 99.17%, respectively). A wide range of sizes was evident at the end of each trial. The WLR of small and large juveniles fit with a negative allometric growth trend. This study highlights the potential production of I. badionotus as early juvenile stages withstand hatchery handling well and exhibit a high SR, reaching commonly released mean sizes (&gt;0.7 g and 25 mm) after almost 3 months (120 days postfertilization).

Assessment of bacterial communities in skin ulceration in cultured sea cucumber Apostichopus japonicus (Selenka)

To determine changes in bacterial composition in skin ulcerations in farmed sea cucumber Apostichopus japonicus, full-length 16S rRNA gene sequencing of different skin samples of A. japonicus was performed on a Pacific Biosciences (PacBio) RS platform. The fact that one of them varies in bacterial diversity than the other two may suggest different stage of skin ulceration, but the answer is inconclusive due to inefficiency in size of sampling pool. After comparing them with three skin samples from three healthy sea cucumbers, respectively, the majority of the results were distinguishable at the species level. The bacterial composition, which increased in diversity during the possible early stage of skin ulceration, exhibited a decrease in diversity at possible advanced stages, except for the predominant Saccharicrinis carchari (846.85 ± 5.75‰). This work may have the first clue implicating Ornithinibacillus contaminans as a potential causative pathogen of skin ulcerations in A. japonicus.

A new tagging method and its early stress effect on the sea cucumber Apostichopus japonicus

The sea cucumber Apostichopus japonicus is a widely exploited species that is highly valued as a traditional medicine and as a food product in China, Singapore, Japan and many other countries of Southeast Asia. With the fast development of sea cucumber fisheries and aquaculture, in-situ investigation is necessary to assess the stock amount, growth and migration of cultured sea cucumbers. Unfortunately, this work is limited for the lacking of effective tagging method for the species. In this study, a calcareous-ring-threading method (CRT method) was tried to tag the sea cucumber A. japonicus. The early stress response of the sea cucumber to tagging operation and invasive tag was monitored so as to evaluate the reliability of the new method. This method had a tag retention rate of 84%, which was higher than the T-bar method (65%), during a 1-month experiment. The results showed that the side effects on large individuals (wet weight above 40g) disappeared after 2days. The individuals with a wet weight below 40g had less tolerance on the new tagging method and couldn't recover after 7days. It is feasible to select large A. japonicus individuals with a wet weight above 60g for this new tagging method. Based on the result of present study, the CRT method is considered to be applicable for tagging A. japonicus individuals with wet weights above 60g.

Sea ranching release techniques for cultured sea cucumber Holothuria scabra (Echinodermata: Holothuroidea) juveniles within the high-energy marine environments of northern Australia

The valuable sea cucumber Holothuria scabra has potential as a ranching species to contribute to the economic growth of northern Australia. However, the high-energy environments of north Australia present certain atypical environmental challenges for sea cucumber ranching, proving commonly practiced ranching techniques ineffective. This study aimed to develop a suitable method for the effective deployment of cultured sea cucumber juveniles within the constraints of north Australian environmental conditions. Two boat-based release techniques were trialed: temporary, floorless cages; and a chute. Sea cucumber recovery rates, dispersal distance and direction were compared to assess the relative merit of each. The proportion of sea cucumbers recovered from the chute release treatment (18.9%) was significantly higher than those from the cage release treatment (10.6%). Recaptured individuals were assigned to their nearest release point, as the tagging method allowed differentiation between methods but not between sites. However, unanticipated sea conditions and equipment failure caused a flawed deployment at one site, which corresponded with atypical recapture results, relative to other sites, and led to the analyses of two possible scenarios explaining sea cucumber movement post-release. Scenario 1 assigned individuals by proximity to release points, and Scenario 2 assigned a group of far-lying individuals to the site where the flawed deployment occurred. There was no significant difference in mean angle (a−) of movement, between the chute and cage methods, for both scenarios (Scenario 1 - 80.3° and 71.16° respectively, Scenario 2 - 81.04° and 74.84° respectively) and the directionality statistic (r) and the angular dispersion (s*) for both methods and scenarios indicate that the strength of any preferred direction was very weak. There was a significant difference in mean distance travelled between the two methods for both scenarios (Scenario 1: cage and chute 10.8m and 20.2m with 95% CI's of 2.57m and 4.42m respectively; Scenario 2: cage and chute 11.1m and 20.4m with 95% CI's of 2.99m and 4.52m respectively). However, this difference is caused primarily by the group of individuals thought to have washed away from the flawed deployment–if these are treated as outliers and removed from overall distance and dispersion analysis, no significant difference is found between distance travelled (F1,184=1.25, p=0.264) or dispersion (F1,165=0.385, p=0.636) between the two methods. The cause of the flawed deployment at one site is easily rectified and, given the significantly higher recovery rates, lower cost, ease of construction and efficiency, the chute release method proved superior. The improved sea ranching release techniques identified in this study will provide practical and economically sound release methods for sea cucumber ranching, and stock enhancement activities across northern Australia.

Identification and functional characterization of first alpha‐2‐macroglobulin in sea cucumbers

The broad-spectrum protease inhibitor alpha-2-macroglobulin (α2M) is widely found in vertebrates and invertebrates. However, no research regarding α2M has been described in sea cucumbers to date. In this study, the first sea cucumber α2M named Stmα2M was identified from Stichopus monotuberculatus, a tropical species with high edible and economic values in Southern China. The Stmα2M cDNA is 5276 bp in length, containing a 5′-untranslated region (UTR) of 279 bp, a 3′-UTR of 344 bp and an open reading frame of 4653 bp that encodes a protein of 1550 amino acids. The Stmα2M possesses all the three characteristics of known α2M proteins, including the bait region domain, thioester domain and receptor-binding domain. Higher levels of mRNA expression were noticed in intestine, respiratory tree, coelomocytes and tentacle of S. monotuberculatus. Transcriptional expression of Stmα2M showed the strongest response to lipopolysaccharides (LPS, 8.19-fold up-regulation) after 6 h post-challenge in coelomocytes. In addition, the α2M activity was detected in S. monotuberculatus and protein activity of α2M increased remarkably at 6 h after LPS stimulation. As a whole, this study indicated that Stmα2M is an important immune-related molecule, and the study on functions of Stmα2M may provide some new and valuable ideas for preventing and controlling diseases of cultured sea cucumbers.

Development of fatty acid biomarkers for the identification of wild and aquacultured sea cucumber (Apostichopus japonicus)

In this study, the fatty acids (FAs) of the organs and tissues of sea cucumber (Apostichopus japonicus) were profiled in order to compare the FA composition of sea cucumber collected from natural habitat (wild) and cages (cultured). The differences in FA contents in dermomuscular tube, peripharyngeal annulus, gonad and intestine (with or without content) between the wild and the cultured were determined. The main fatty acids in all organs and tissues were 20:5n-3, 16:1n-7, 20:4n-6, 22:6n-3, 18:0, and 18:1n-7. The basically different FAs of body wall and digestive tube were 16:1n-7, 18:1n-9 and 20:1n-11. The ratio of saturated to mono- and polyunsaturated FAs in digestive tube was independent on inside content while there was a redistribution of the total amount of n-3 and n-6 fatty acids. The comparison of FA composition of the wild and the cultured sea cucumber showed that 20:5n-3, 16:1n-7 and 18:1n-7 predominated the wild while 20:4n-6 predominated the cultured. The content of branched-chain fatty acids in the wild was 3%–4% and about 9% in the cultured. The possible FAs for identifying the wild and the cultured sea cucumbers were selected. It was suggested that the indexes such as the ratio of either (n-3:n-6) to (n-7:n-6) or (n-3) + (n-7) to (n-6) may serve as the biomarkers distinguishing the wild and the cultured sea cucumber.

Dietary Cordyceps militaris protects against Vibrio splendidus infection in sea cucumber Apostichopus japonicus.

Vibrio splendidus is the common pathogen that causes infectious diseases widely spread in cultured sea cucumber in China. Therefore, we investigated the ability of Cordyceps militaris to protect against infection caused by V. splendidus. In this study, sea cucumbers were fed with a diet containing 0 (control), 1%, 2% or 3% C. militaris for 28 days, and subsequently challenged with V. splendidus by injection with 1.0 × 10(9) cfu per animal. Parameters of immune response such as phagocytosis (PC), lysozyme (LSZ) activity, superoxide dismutase (SOD) activity, alkaline phosphatase (AKP) activity and acid phosphatase (ACP) activity were determined on days 0, 1, 3, 5 and 7 after injection. The results showed that dietary C. militaris at a dose of 2% or 3% significantly up-regulated (P < 0.05) all the immune parameters on day 0. One day after injection with V. splendidus, all the immune indices except ACP exhibited a tendency to decrease and then increase again, returning to the initial level on days 5 and/or 7 after injection. All the immune parameters of those fed with C. militaris were found significantly higher (P < 0.05) than those of the control group on day 1 after injection. Only LSZ activity of those fed with 1%- or 3%-C. militaris diet on day 5 showed significantly increases (P < 0.05) than the controls. As for ACP activity, the values remained steady with time, but with significant increase (P < 0.05) seen in sea cucumbers fed with 2%-C. militaris diet, and lasted for up to 7 days after V. splendidus injection. The cumulative mortality of sea cucumbers fed with the basal diet followed V. splendidus infection was significantly higher (P < 0.05) than those fed with 2% and 3% C. militaris diet. Under the experimental conditions, dietary C. militaris could enhance the immune responses of Apostichopus japonicus and improve its resistance to infection by V. splendidus.

Effect of culture methods on individual variation in the growth of sea cucumber Apostichopus japonicus within a cohort and family

There is substantial individual variation in the growth rates of sea cucumber Apostichopus japonicus individuals. This necessitates additional work to grade the seed stock and lengthens the production period. We evaluated the influence of three culture methods (free-mixed, isolated-mixed, isolated-alone) on individual variation in growth and assessed the relationship between feeding, energy conversion efficiency, and individual growth variation in individually cultured sea cucumbers. Of the different culture methods, animals grew best when reared in the isolated-mixed treatment (i.e., size classes were held separately), though there was no difference in individual variation in growth between rearing treatment groups. The individual variation in growth was primarily attributed to genetic factors. The difference in food conversion efficiency caused by genetic differences among individuals was thought to be the origin of the variance. The level of individual growth variation may be altered by interactions among individuals and environmental heterogeneity. Our results suggest that, in addition to traditional seed grading, design of a new kind of substrate that changes the spatial distribution of sea cucumbers would effectively enhance growth and reduce individual variation in growth of sea cucumbers in culture.

Characterization of antimicrobial resistance of Vibrio parahaemolyticus from cultured sea cucumbers (Apostichopus japonicas )

This study was aimed to evaluate the antimicrobial resistance and molecular resistance mechanisms of 87 Vibrio parahaemolyticus isolates from cultured sea cucumbers (Apostichopus japonicus). The results showed that all isolates were resistant to ampicillin and cephazolin, fewer of them were resistant to streptomycin (43·7%), cefuroxime sodium (18·4%), tetracycline (4·6%), sulphamethoxazole/trimethoprim (2·3%) and four quinolones (2·3%). More than half (56·2%) of the isolates displayed multiple resistance to at least three antimicrobials. The resistance genes were detected in all antimicrobial-resistant isolates except two tetracycline-resistant isolates. Among all these tested resistance genes, blaTEM , sul2, strA and strB were predominant, and none of blaSHV , blaCTX-M , blaOXA , sul1, sul3, tetA, tetM and tetQ genes was detected. Point mutations were found in quinolone resistance-determining regions of gyrA and parC genes in quinolone-resistant isolates. All isolates harboured class 1 integrons but only one carried gene cassette without any resistance genes, and none of them was positive to class 2, 3 integrons and SXT constins. These results indicate that the antimicrobial-resistant V.parahaemolyticus isolates from sea cucumbers and resistance genes could be potential risks to public health or other environments. This study is the first report on characterization of antimicrobial resistance of Vibrio parahaemolyticus from sea cucumbers (Apostichopus japonicus). Our findings reveal a high level of resistance to some antimicrobials and prevalence of the resistance genes in V.parahaemolyticus isolates from sea cucumbers and underline the need for prudent use of antimicrobials in aquaculture to minimize the spread of antimicrobial-resistant V.parahaemolyticus.

A preliminary study of effects of mild and acute drop of temperature on serum non-specific immunity in“Shuiyuan No.1”sea cucumber populations and the cultured sea cucumber populations

The experiment studied the change of enzymes in mild and acute drop of temperature.The activities of CAT,SOD,POD and the content of MDA in Shuiyuan No.1 sea cucumber and cultured sea cucumber were analyzed.The results show that:(1)In terms of mild drop in temperature,the activity of CAT were trend to decreased and then increased in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber,the activities of CAT were 402.78-424.32 U/mL and 409.81-430.08 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the activity of SOD and POD first increased and then decreased and then increased in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the activities of SOD were 0.019-0.086 U/mL and 0.014-0.069 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber,the activities of POD were 0.000 45-0.000 89 U/mL and 0.000 24-0.000 66 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the activity of MDA first increased and then reduced in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber,the content of MDA were 5.83-9.79 nmol/mL and 7.57-9.90 nmol/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber.(2)In terms of acute drop in temperature,the activity of CAT,SOD and MDA first increased and then reduced in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber,the activities of CAT were 382.51-409.71 U/mL and 383.86-399.42 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the activities of SOD were 0.023-0.038 U/mL and 0.025-0.035 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the content of MDA were 5.83-9.79 nmol/ml and 5.57-9.90 nmol/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber;the activity of POD were first increased and then decreased and then increased again to reduce,the activities of POD were 0.000 20-0.000 70 U/mL and 0.000 18-0.000 40 U/mL in Shuiyuan No.1 sea cucumber and Dalian cultured sea cucumber.(3)Both the activities of CAT,SOD,POD and the content of MDA were changed in the different ways of dropping temperature and the changing in Shuiyuan No.1 sea cucumber was more sensitive than in Dalian cultured sea cucumber in the terms of mild and acute drop in temperature.The activities of CAT and POD was higher in Shuiyuan No.1 sea cucumber than in Dalian cultured sea cucumber;the content of MDA was larger in the terms of acute drop than in the terms of mild drop in temperature.These results revealed that there are different immune responses to sea cucumber in different drops of temperature patterns.Shuiyuan No.1 sea cucumber was more sensitive and has higher capacity of antioxidant than Dalian cultured sea cucumber in the low temperature environment.