Effect of water temperature on digestive enzyme activity and gut mass in sea cucumber Apostichopus japonicus (Selenka), with special reference to aestivation

The effect of water temperature on gut mass and digestive enzyme activity in sea cucumber Apostichopus japonicus, including relative gut mass (RGM), amylase, lipase, pepsin and trypsin activities were studied at temperatures of 7, 14, 21, and 28A degrees C over a period of 40 days. Results show that RGM significantly decreased after 40 days at 21A degrees C and markedly decreased over the whole experiment period at 28A degrees C; however, no significant effect of duration was observed at 7 or 14A degrees C. At 14A degrees C, trypsin activity significantly decreased over 10 and 20 days, then increased; amylase and trypsin activity significantly decreased after 40 days at 28A degrees C. However, no significant effect of duration was found on amylase, pepsin or trypsin activities in the other temperature treatment groups. At 28A degrees C, lipase activity peaked in 20 days and then markedly decreased to a minimum at the end of the experiment. On the other hand, pepsin activity at 28A degrees C continuously increased over the whole experimental period. Principle component analysis showed that sea cucumbers on day 40 in the 21A degrees C group and in the previous 20 days in the 28A degrees C group were in the prophase of aestivation. At 28A degrees C, sea cucumbers aestivated at 30-40 days after the start of the experiment. It is concluded that the effect of temperature on the digestion of A. japonicus is comparatively weak within a specific range of water temperatures and aestivation behavior is accompanied by significant changes in RGM and digestive enzyme activities.

Bioenergetic responses of sub-adult sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea) to temperature with special discussion regarding its southernmost distribution limit in China

1. This paper investigated the bioenergetic responses of the sea cucumber Apostichopus japonicus (wet weights of 36.5 +/- 1.2 g) to different water temperatures (5, 10, 15, 20, 25 and 30 degrees C) in the laboratory. 2. Results showed that theoretically the optimal temperatures for energy intake and scope for growth (SFG) of sub-adult A. japonicus was at 15.6 and 16.0 degrees C, respectively. The aestivation threshold temperature for this life-stage sea cucumber could be 29.0 degrees C by taking feeding cessation as the indication of aestivation. 3. Our data suggests that A. japonicus is thermo-sensitive to higher temperature, which prevents it from colonising sub-tropical coastal zones. Therefore, water temperature plays an important role in its southernmost distribution limit in China. 4. The potential impact of global ocean warming on A. japonicus might be a northward shift in the geographical distribution. Crown Copyright (C) 2009 Published by Elsevier Ltd, All rights reserved.

Comparative researches on effects of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate upon Lateolabrax japonicus biomarker system

Fish Lateolabrax japonicus were exposed to anion surfactant sodium dodecylbenzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS) at 1 mg/l, respectively, for 6, 12 and 18 d, with one control group. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH) and glutathione S-transferase (GST) were determined; brain acetylcholinesterase (AChE) and liver inducible nitric oxide synthase (NOS) activities were also measured. The results of the study indicated that these parameters made different, sometimes, adverse responses to SDBS and SDS exposure, such as the activity of NOS can be inhibited by SDBS and induced by SDS, the different physico-chemical characteristics of SDBS and SDS should be responsible for their effects on enzyme activities. (c) 2005 Elsevier B.V. All rights reserved.

Spatial distribution of ciliates, copepod nauplii and eggs, Engraulis japonicus post-larvae and microzooplankton herbivorous activity in the Yellow Sea, China

The abundance of anchovy Engraulis japonicus larvae, >20 mum ciliates, copepod eggs and nauplii, and microzooplankton herbivorous activity were studied in the Yellow Sea in June 2000. Anchovy juveniles and larvae were found in only 6 of the 19 stations sampled. The ciliate communities were dominated by 2 species: Laboea strobila and Strombidium compressum. In the surface waters, the abundance of L. strobila ranged between 0 and 560 ind. l(-1). S. compressum only appeared at Stns 15 to 18 (20 to 3300 ind. l(-1)). L. strobila was found mainly in the top 20 m. The abundance of L. strobila was less than 50 ind, l(-1) in waters deeper than 25 m. S, compressum showed subsurface abundance peaks at the salinity abnormality. Tintinnids occurred occasionally with abundance lower than 100 ind. l(-1), The total ciliate abundance fell in the range of 40 to 3420 ind. l(-1). The ciliate biomass in the surface water and the water column ranged between 0,15 and 6.76 mug C l(-1) and 0.4 and 134.4 mg C m(-2), respectively, In the surface waters, the abundance of copepod eggs and nauplii ranged from 0,3 to 3.1 and 1,1 to 15.6 ind, l(-1), respectively. The average abundance of copepod eggs and nauplii in 4 depth (0, 5, 10 and 20 m) fell in the range of 0.2 to 2.8 and 1.0 to 29.4 ind. l(-1), respectively. As a food item of the E. japonicus post-larvae, the abundance of copepod nauplii and eggs appeared to be low. The abundance peaks of ciliate and E, japonicus post-larvae coincided. Although not found in the gut of E, japonicus post-larvae, aloricate ciliates might be ingested by first-feeding anchovy larvae, preventing initial starvation and prolonging the time to irreversible starvation. On the basis of dilution experiments with positive microzooplankton grazing rates, microzooplankton grazed at rates of 0 to 0.61 d(-1). Grazing pressure of microzooplankton on chlorophyll a standing stock (P-i) and potential chlorophyll a primary production (P-p) were 17 to 46% and 35 to 109% d(-1), respectively.

Phenotypic plasticity of gut structure and function during periods of inactivity in Apostichopus japonicus

Apostichopus japonicus is a common sea cucumber that undergoes seasonal inactivity phases and ceases feeding during the summer months. We used this sea cucumber species as a model in which to examine phenotypic plasticity of the digestive tract in response to food deprivation. We measured the body mass, gross gut morphology and digestive enzyme activities of A. japonicus before, during, and after the period of inactivity to examine the effects of food deprivation on the gut structure and function of this animal. Individuals were sampled semi-monthly from June to November (10 sampling intervals over 178 days) across temperature changes of more than 18 degrees C. On 5 September, which represented the peak of inactivity and lack of feeding, A. japonicus decreased its body mass, gut mass and gut length by 50%, 85%, and 70%, respectively, in comparison to values for these parameters preceding the inactive period. The activities of amylase, cellulase and lipase decreased by 77%, 98%, and 35% respectively, in comparison to mean values for these enzymes in June, whereas pepsin activity increased two-fold (luring the inactive phase. Alginase and trypsin activities were variable and did not change significantly across the 178-day experiment. With the exception of amylase and cellulase, all body size indices and digestive enzyme activities recovered and even surpassed the mean values preceding the inactive phase during the latter part of the experiment (October-November). Principal Component Analysis (PCA) utilizing the digestive enzyme activity and body size index data divided the physiological state of this cucumber into four phases: an active stage, prophase of inactivity peak inactivity, and a reversion phase. These phases are all consistent with previously suggested life stages for this species, but our data provide more defined characteristics of each phase. A. japonicus clearly exhibits phenotypic plasticity (or life-cycle staging) of the digestive tract during its annual inactive period. (C) 2008 Elsevier Inc. All rights reserved.

Studies on the transmission of WSSV (white spot syndrome virus) in juvenile Marsupenaeus japonicus via marine microalgae

We studied the possible role that marine microalgae may play during the outbreaks of WSS (white spot syndrome). In order to elucidate the possibility of marine microalgae carrying WSSV (white spot syndrome virus), six marine microallgae (Isochr.vsis galbana, Skeletonema costatum, Chlorella sp., Heterosigma akashiwo, Scrippsiella trochoidea, Dunaliella salina) were co-cultured with adult Marsupenaeus japollicus infected with WSSV and were assayed daily by nested-PCR to study whether they could carry WSSV. Further experiments were conducted to investigate whether the virus carried by microalgae could re-infect juvenile M. japonicus. Results showed that all of the experimental microalgae, except H. akashiwo could carry WSSV, and among them, Chlorella sp. and S. trochoidea had the strongest WSSV-carrying ability. Unlike other invertebrate carriers of WSSV, the WSSV detections in microalgae, which were positive after I and 3 days, were negative after 10 days of incubation. WSSV detection results in juvenile M. japonicus showed that the juvenile shrimp were re-infected by co-cultured Chlorella sp., although the juvenile M. japonicus carried so small an amount of WSSV that it could only be detected by nested-PCR. The results of this experiment suggest that microalgae might be one possible horizontal transmission pathway for WSSV. Further research, however, is required to better understand the factors behind the different carrying abilities and virus-carrying mechanisms of different microalgae. (c) 2007 Elsevier Inc. All rights reserved.

Effects of acute temperature or salinity stress on the immune response in sea cucumber, Apostichopus japonicus

Invertebrates are increasingly raised in mariculture, where it is important to monitor immune function and to minimize stresses that could suppress immunity. The activities of phagocytosis, superoxide dismutase (SOD), catalase (CAT), myeloperoxiclase (MPO), and lysozyme (LSZ) were measured to evaluate the immune capacities of the sea cucumber, Apostichopus japonicus, to acute temperature changes (from 12 degrees C to 0 degrees C, 8 degrees C, 16 degrees C, 24 degrees C, and 32 degrees C for 72 h) and salinity changes (from 30 parts per thousand to 20 parts per thousand, 25 parts per thousand, and 35 parts per thousand for 72 h) in the laboratory. Phagocytosis was significantly affected by temperature increases in 3 h, and by salinity (25 parts per thousand and 35 parts per thousand) changes in 1 h. SOD activities decreased significantly in 0.5 h to 6 h samples at 24 degrees C. At 32 degrees C, SOD activities decreased significantly in 0.5 h and 1 h exposures, and obviously increased for 12 h exposure. CAT activities decreased significantly at 24 degrees C for 0.5 h exposure, and increased significantly at 32 degrees C in 3 h to 12 h exposures. Activities of MPO increased significantly at 0 degrees C in 0.5 h to 6 In exposures and at 8 degrees C for 1 h. By contrast, activities of MPO decreased significantly in 24 degrees C and 32 degrees C treatments. In elevated-temperature treatments, activities of LSZ increased significantly except at 32 degrees C for 6 h to 12 h exposures. SOD activity was significantly affected by salinity change. CAT activity decreased significantly after only 1 h exposure to salinity of 20 parts per thousand.. Activities of MPO and LSZ showed that A. japonicus tolerates limited salinity stress. High-temperature stress had a much greater effect on the immune capacities of A. japonicus than did low-temperature and salinity stresses. Crown Copyright (C) 2008 Published by Elsevier Inc. All rights reserved.

Immune condition of Apostichopus japonicus during aestivation

Aestivation is an indispensable state in the life history of sea cucumbers, Apostichopus japonicus. The immune characteristics of the coelomic fluid of A. japonicus, were investigated during aestivation. Samples were collected between July and November 2006 from a coastal pond located off the Yellow Sea in Jiaonan, Shandong Province, China. The total coelomocytes counts (TCC), total superoxide dismutase (T-SOD), catalase (CAT), myeloperoxidase (MPO), and lysozyme (IZM) in the coelomic fluid were measured. The activities of catecholamines, [adrenaline (AD), noradrenaline (NA), and dopamine (DOP)] were estimated. TCC decreased from July to September, indicating weakness of the cellular immune activity at that time. Activities of SOD, CAT, MPO, and LZM changed significantly from July to October. Catecholamines AD and NA in coelomic fluid were significantly higher on August 21 and November 27. There was no significant variation in DOP during the sampling period. Thus, immune characters in coelomic fluid of A. japonicus changed significantly during aestivation. Water temperature was significantly and negatively correlated with TCC, and salinity was significantly and positively correlated with AD and NA. The mechanism of aestivation in A. japonicus is complex and might not be attributed only to environmental changes, such as temperature and salinity, as shown in previous studies. (C) 2008 Elsevier B.V. All rights reserved.

Effects of rearing temperature and density on growth, survival and development of sea cucumber larvae, Apostichopus japonicus (Selenka)

In laboratory conditions, effects of rearing temperature and stocking density were examined on hatching of fertilized egg and growth of auricularia larvae of Apostichopus japonicus respectively. Data series like larval length and density, metamorphic time, and survival rate of the larvae were recorded. Statistics showed that for A. japonicus, survival rate (from fertilized egg to late auricularia) decreased significantly with the increasing rearing temperature (P < 0.05). At different temperatures SGR was statistically significant as well (P < 0.05) from day 1, and maximal SGR was found on day 9 at 24A degrees C (159.26 +/- 3.28). This study clearly indicated that at low temperature (< 24A degrees C), metamorphic rate was remarkably higher than at higher temperature (> 26A degrees C). Hatching rate was significantly different between 0.2-5 ind./ml groups and 20-50 ind./ml groups. Rearing larvae at the higher density had the smaller maximal-length, whereas needed longer time to complete metamorphosis. This study suggested that 21A degrees C and 0.4 ind./ml can be used as the most suitable rearing temperature and stocking density for large -scale artificial breeding of A. japonicus's larvae.

Effects of salinity on energy budget in pond-cultured sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea)

Pond farming for sea cucumber has developed rapidly along the northern coast of China in the recent years. Holothurians inhabiting ponds undergo seasonal fluctuations of salinity. This study deals with the bioenergetic responses of pond-cultured sea cucumbers Apostichopus japonicus (wet weight of 37.5 +/- 1.8 g) to different water salinities [22, 27, 31.5, and 36 practical salinity units (psu)] at 15 degrees C in the laboratory to determine the influence of water salinity on growth and energy allocation in this species. Results show that ingested energy and scope for growth (SFG) were highest at 31.5 psu and then decreased when water salinity was below or above this point. Although energy ingested was lowest at 36 psu, the lowest SFG occurred at 22 psu (only 102.68 +/- 14.26 J g(-1) d(-1)) because animals reared at 22 psu spent much more consumed energy on feces (72.19%), respiration (21.70%), and excretion (2.59%), leaving less energy for growth (3.52%). Results suggest that pond-cultured sea cucumbers could tolerate chronic salinity fluctuations at a range of 22 to 36 psu and grew better between 27 and 31.5 psu, but decreased at salinities above and below the mentioned salinity range. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Studies on nitric oxide synthase activity in haemocytes of shrimps Fenneropenaeus chinensis and Marsupenaeus japonicus after white spot syndrome virus infection

The nitric oxide synthase (NOS) activity in the haemocytes of shrimps Fenneropenaeus chinensis (Osbeck) and Marsupenaeus japonicus (Bate) was Studied after white spot syndrome virus (WSSV) infection to determine its characteristics in response to virus infection. First, the NOS activity in haemocytes of shrimps was determined by the means of NBT reduction and changes in cell conformation. And the variations of NOS activity in shrimps after challenge with WSSV intramuscularly were evaluated through the analysis Of L-citrulline and total nitrite/nitrate (both as NO derivates) concentrations. The result showed that NOS activity in the haemocytes of F chinensis increased slightly from 0 to 12 h postchallenge, indicated by the variations Of L-Citrulline (from 11.15 +/- 0.10 to 12.08 +/- 0.64 mu M) and total nitrite/nitrate concentrations (from 10.45 +/- 0.65 to 12.67 +/- 0.52 mu M). Then it decreased sharply till the end of the experiment (84 h postchallenge), the concentrations Of L-Citrulline and total nitrite/nitrate at 84 It were 1.58 +/- 0.24 and 2.69 +/- 0.70 mu M, respectively. The LPS-stimulated NOS activity kept constant during the experiment. However, in M. japonicus, the NOS activity kept increasing during the first 72 It postchallenge, the concentrations Of L-Citrulline and total nitrite/nitrate increased from 7.82 +/- 0.77 at 0 h to 10.79 +/- 0.50 mu M at 72 h, and from 8.98 +/- 0.43 at 0 h to 11.20 +/- 0.37 mu M at 72 h, respectively. Then it decreased till the end of the experiment (216 h postchallenge), and the concentrations of L-Citrulline and total nitrite/nitrate at 216 h were 5.66 +/- 0.27 and 4.68 +/- 0.16 mu M, respectively. More importantly, an apparent increase of I-PS-stimulated NOS activity was observed in M japonicus at 48 h postchallenge, which was about 4 times higher than that in the control group of health shrimps. In correspondence with the difference of NOS activity between the two species of shrimps, the Cumulative mortalities of the shrimps were also different. All shrimps of F. chinensis in the mortality experiment died in 66 h, much more quickly than M. japonicus, Whose accumulative mortality reached 100% after 240 h. Data here reported let us hypothesize that NOS activity in the haemocytes of shrimps F chinensis and M. japonicus responses to WSSV infection differently, and this might be one of the reasons for the different susceptibility of F chinensis and M. japonicus to WSSV infection. (c) 2005 Elsevier Inc. All rights reserved.

Response of integrated biomarkers of fish (Lateolabrax japonicus) exposed to benzo[a]pyrene and sodium dodecylbenzene sulfonate

Fish Lateolabrax japonicus were exposed to 0.1 and 1 mg/L of anion surfactant sodium dodecylbenzene sulfonate (SDBS) and to 2 and 20 mu g/L of benzo[a]pyrene (B[a]P) for 6, 12, and 18 days, with control and solvent control groups. Liver antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and glutathione S-transferase (GST), were determined; brain acetyleholinesterase (AChE) and liver inducible nitric oxide synthase (iNOS) activities were also measured. The results indicated that (1) L. japonicus avoided oxidative damage through antioxidant systems; (2) SOD, GPx, and GSH were induced, and GST was inhibited and then induced by B[a]P exposure; and (3) CAT, GPx, and AChE were induced while NOS was inhibited, and GST was induced and then inhibited by SDBS stress in experimental period. (c) 2005 Elsevier Inc. All rights reserved.

Metabolic characteristics of sea cucumber Apostichopus japonicus (Selenka) during aestivation

Metabolic characteristics of the sea cucumber Aposticholpus japonicus (Selenka) during aestivation were studied in the laboratory. The effects of water temperature on oxygen consumption rate (OCR) and ammonia-N excretion rate (AER) in A. japonicus were determined by the Winkler and Hypobromite methods, respectively. Mature (large, 148.5 +/- 15.4 g, medium 69.3 +/- 6.9 g) and immature (small, 21.2 +/- 4.7 g) individuals aestivated at water temperatures of 20 and 25 degrees C, respectively. The metabolic characteristics of mature individuals were different from immature individuals during this period. The OCR of mature sea cucumbers peaked at 20 degrees C, and then dropped significantly at higher temperatures, whereas the OCR of the immature animals continued to increase slightly, even beyond the aestivation temperature. The AER of mature individuals peaked at 20 T, while that of the immature animals peaked at 25 degrees C. The relationships between dry weight (DW) and absolute oxygen consumption (R) and absolute ammonia-N excretion (N) could be described by the regression equation R or N=aW(b). With the exception of 15 degrees C, the O/N ratios (calculated in atomic equivalents) of large size sea cucumbers was close to 20 across the temperatures used in this study, indicating that their energy Source was a combination of lipid and protein. Oil the other hand, apart from small individuals maintained at 10 degrees C, the O/N ratios of the medium and small sea Cucumbers were close to 10, indicating that protein was their major energy source. The O/N ratios in all size groups remained unchanged after aestivation was initiated. (c) 2005 Elsevier B.V. All rights reserved.

The influence of diets containing dried bivalve feces and/or powdered algae on growth and energy distribution in sea cucumber Apostichopus japonicus (Selenka) (Echinodermata : Holothuroidea)

In recent years, bivalve feces and powdered algae have been used as the food sources of holothurians in China. In this study, growth and energy budget for sea cucumber Apostichopus japonicus (Selenka) with initial wet body,veights of 32.5 1.0 g (mean +/- SE, n=45) when fed with five different granule diets containing dried bivalve feces and/or powdered algae in water temperature 13.2-19.8 degrees C and salinity 30-32ppt were quantified in order to investigate how diets influence growth and energy distribution and to find out the proper diet for land-based intensive culture of this species. Results showed that diets affected the food ingestion, feces production, food conversion efficiency and apparent digestive ratios, hence the growth and energy budget. Sea cucumbers fed with dried feces of bivalve showed poorer energy absorption, assimilation and growth than individuals fed with other four diets; this could be because feces-drying process removed much of the benefits. Dried bivalve feces alone, therefore, were not a suitable diet for sea cucumbers in intensive cultivation. The mixed diets of feces and powered algae showed promising results for cultivation of sub-adult Apostichopus japonicus, while animals fed with powdered algae alone, could not obtain the best growth. According to SGR of tested animals, a formula of 75% feces and 25% powdered algae is the best diet for culture of this species. Extruded diets were used in the present experiment to overcome shortcomings of the traditional powdered feeds, however, it seems a conflict exists between drying bivalve feces to form extruded diets and feeding sea cucumbers with fresh feces which contain beneficial bacteria. Compared with other echinoderms, in holothurians the energy deposited in growth is lower and the energy loss in feces accounts for the majority of the ingested energy. Such detailed information could be helpful in further development of more appropriate diets for culture of holothurians. (c) 2006 Elsevier B.V. All rights reserved.