影响西藏卤虫无节幼体在淡水中存活时间的几个因素分析

为对水产养殖育苗实践中活体饵料西藏卤虫(Antemia tibetiana)的应用提供参考, 研究不同钠盐对孵化率、无节幼体在淡水中存活时间的影响, 分析NaCl浓度、孵化液pH和淡水水温等因素对西藏卤虫无节幼体在淡水中存活时间, 记录各组无节幼体在淡水中50%和100%死亡所需时间。结果表明, 不同钠盐显著影响西藏卤虫的孵化率, Na₂SO₄组显著高于NaCl组(P<0.05), Na₂CO₃组显著低于NaCl组(P<0.01), 其他各组之间差异不显著(P>0.05)。以NaCl组孵化出的无节幼体在淡水中存活时间最长, 50%存活时间达13h, Na₂SO₄组孵化的无节幼体存活时间显著低于NaCl组(P<0.05), 而Na₂CO₃和NaNO₃组存活时间极显著低于NaCl组(P<0.01), 在Na₂CO₃中孵化的无节幼体死亡速度最快。孵化率高的实验组存活时间不是最长, 显示孵化率与存活率之间并无关联性。随着孵化液NaCl浓度升高, 无节幼体在淡水中存活时间逐渐延长, 至35‰时达到最高, 但当孵化液NaCl浓度达40‰时, 存活时间开始下降。随着孵化液pH从6.5—8.0逐渐升高, 存活时间逐渐延长, 至pH8.0时达到最高, 孵化液pH继续升高, 存活时间逐渐缩短, 到pH10.0时, 50%存活时间只有3.54h, 死亡速度最快, pH8.0组与其他实验组相比较差异显著(P<0.05)。在5℃淡水中无节幼体50%死亡时间为18.54h, 显著长于15℃水温组, 当水温≥20℃时, 所有组别50%存活时间短于水温15℃组, 差异显著(P<0.05)。孵化时钠盐的种类、NaCl浓度、孵化液pH和淡水水温对西藏卤虫无节幼体在淡水中存活时间有显著影响。     

Sodium-calcium exchange in membrane vesicles from Artemia

Membrane vesicles were prepared from Artemia nauplii (San Francisco Bay variety) 45 h after hydration of the dry cysts. Na+-loaded vesicles accumulated up to 10 nmol Ca2+/mg protein when diluted 50-fold into 160 mM KCl containing 15 microM CaCl2. Practically no accumulation of Ca2+ was observed if the vesicles were diluted into 160 mM NaCl instead of KCl, or if they were treated with monensin, a Na+ ionophore, for 30 s prior to addition of CaCl2 to the KCl medium. These observations indicate that the Artemia vesicles exhibit Na-Ca exchange activity. The velocity of Ca2+ accumulation by the vesicles in KCl was stimulated 2.6-fold by the K+ ionophore valinomycin, suggesting that the exchange system is electrogenic, with a stoichiometry greater than 2Na+ per Ca2+. Km,Ca and Vmax values were 15 microM and 7.5 nmol/mg protein.s, respectively. Exchange activity in the Artemia vesicles was inhibited by benzamil (IC50 approximately equal to 100 microM) and by quinacrine (IC50 approximately equal to 250 microM), agents that also inhibit exchange activity in cardiac sarcolemmal vesicles. Unlike cardiac vesicles, however, exchange activity in Artemia was not stimulated by limited proteolysis, redox reagents, or intravesicular Ca2+. This indicates that the two exchange systems are regulated by different mechanisms. Vesicles were prepared from Artemia at various times after hydration of the dry cysts and examined for exchange activity. Activity was first observed at approximately 10 h after hydration and increased to a maximal value by 30-40 h; hatching of the free swimming nauplii occurred at 18-24 h. The results suggest that hatching Artemia nauplii might be a particularly rich source of mRNA coding for the Na+-Ca2+ exchange carrier.     

Growth of Perca fluviatilis larvae fed with Artemia spp. nauplii and the effects of initial starvation

Experiments were performed to test the growth and survival of perch larvae fed with Artemia spp. nauplii and to determine the most advantageous time of first feeding. During a first experiment, perch larvae were divided into groups according to their hatching dates. Daily ingestion of Artemia spp. nauplii began significantly 2 days after mass larvae hatching. By day 7, the daily prey acceptance was over 75% among the separate larvae groups. During a second 14-day feeding experiment, larvae fed after a 2- or a 3-day delay showed the best growths: 12.5 mm and 13.7 mg. There was no significant difference (P > 0.05) among survival rates (85.3%) of perch larvae fed after a 1-, 2- or 3-day delay.     

Drug assimilation in the tissue of European sea bass (Dicentrarchus labrax) fry delivered orally through bioencapsulation

Assimilation levels of the antibacterials trimethoprim (TMP) and sulfamethoxazole (SMX) in sea bass ( Dicentrarchus labrax ) fry tissue administered orally were investigated. A 1:5 TMP and SMX combination incorporated in an oil emulsion (Selco) at 20 % and 40 % concentrations (w/w) were bioencapsulated in Artemia (Instar II) nauplii. Chemotherapeutics-loaded ('medicated') nauplii were fed to the sea bass fry and drug concentrations in the tissue were analysed by high-performance liquid chromatrography (HPLC). Fish fed 40 %'medicated' Artemia assimilated significantly higher levels of chemotherapeutics compared with those fed 20 %'medicated' Artemia. Chemotherapeutics given at 40 % reached peak levels (19.3 μg TMP/g DW and 23.31 μg SMX/g DW) within 2 h while those at 20 % peaked (8.74 μg TMP/g DW and 6.73 fig SMX/g DW) after 5 h. TMP persisted in the tissues longer (up to 72 h) than SMX (12–16 h), suggesting a more efficient uptake and retention of the former and/or faster metabolism and elimination of the latter.     

The bacterial storage compound poly-beta-hydroxybutyrate protects Artemia franciscana from pathogenic Vibrio campbellii

Infections caused by antibiotic-resistant luminescent Vibrios can cause dramatic losses in aquaculture. In this study, the short-chain fatty acid beta-hydroxybutyrate and its polymer poly-beta-hydroxybutyrate were investigated as possible new biocontrol agents. beta-Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100 mM. Moreover, the addition of 100 mM of this fatty acid to the culture water of Artemia nauplii infected with the V. campbelli strain significantly increased the survival of the nauplii. As Artemia is a non-selective and particle filter feeder, we also investigated whether poly-beta-hydroxybutyrate particles could be used to protect Artemia from the pathogenic V. campbellii. The addition of 100 mg l(-1) poly-beta-hydroxybutyrate or more to the Artemia culture water offered a preventive and curative protection from the pathogen as a significantly enhanced survival was noticed. If added as a preventive treatment, a complete protection of infected nauplii (no significant mortality compared with uninfected nauplii) was observed at 1000 mg l(-1) poly-beta-hydroxybutyrate. Our data indicate that the use of poly-beta-hydroxybutyrate might constitute an ecologically and economically sustainable alternative strategy to fight infections in aquaculture.     

Biological and biochemical quality of the Artemia (Anostraca: Artemiidae) population from Real de Salinas saltworks, Calkiní, Campeche, Mexico

Cysts of Artemia spp. collected from February 1997 to February 2000 in the Real de Salinas solar saltworks, Campeche, Mexico, were compared with Artemia franciscana (batch number 8,131 Microfeast Artemia Cysts, Texas, USA). The variables determined in these two populations were: number of cysts per gram, hatching percentage, hatching efficiency, hatching rate, hatching synchrony and hatching biomass, as well as diameter of the cysts and length of the nauplii (instar I). For Salinas, the average diameters of the encapsulated and decapsulated cysts were 230.5 +/- 4.14 and 221.8 +/- 3.39 microm, respectively. The thickness of the cyst shell was 4.35 +/- 0.68 microm and the length of the nauplii was 388.11 +/- 4.39 microm, this last value is among the smallest reported in the literature. For the commercial population of A. franciscana, the average diameters of the encapsulated and decapsulated cysts were 230.21 +/- 12.49 and 216.96 +/- 13.71, respectively. With respect to the corion thickness and length of the nauplii the values were 6.62 +/- 2.72 and 424.70 +/- 30.08, respectively. The protein value of the cysts (47.91 %) and nauplii (50.5 %) of Artemia population from Real de Salinas, are considered adequate to be used as food in aquaculture. The results indicate that the population from Real de Salinas presents positive features for its use in aquaculture in the region.     

The Effect of Gamma Radiation on Parthenogenetic Artemia (Branchiopoda,Anostraca) Cysts: Nauplius Hatching and Postnauplial Survival under Varying Salinity

Biology Bulletin - Abstract—The effect of gamma radiation doses of 2.5, 5.5, and 7.5 Gy received by Artemia cysts on hatching of nauplii and postnauplial survival of crustaceans has been...     

Trypsin activity and physiological aspects in larval rearing of European sea bass (Dicentrarchus labrax) using live prey and compound diets

The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae ( Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey ( Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length < 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.     

Growth and survival of tench larvae fed under different feeding strategies

Two feeding experiments were conducted to evaluate the growth and survival rates of tench Tinca tinca L. larvae when initially fed with a combination of three different brands of Artemia nauplii under two conditions: (A) in the laboratory and (B) on a commercial farm. At the same time, a protozoan culture of the freshwater ciliate Colpoda cucullus was additionally tested in one of the experiments to possibly enhance the initial hunting behaviour of the larvae. The larvae were fed every 4 h from the onset of exogenous feeding up to 14 days of age. Three types of commercial Artemia products, mainly differing in size and high unsaturated fatty acid (HUFA) content, were used. One group was fed with C. cucullus as a starter. The different combinations of Artemia nauplii were used to evaluate possible effects on larval growth. The final growth at 26.3 °C, expressed in length and weight, did not show significant differences, suggesting the use of the most economically feasible Artemia strain studied. The experiments confirmed that using smaller prey during the first 2 days of feeding increases their survival rate, although the mean final survival rate was high (89%). In the experiment carried out at the commercial fish farm facilities, experimental groups were also fed with Artemia nauplii, using the EG type either enriched or not enriched with HUFA. Again, one of the groups was offered the ciliate C. cucullus as initial feed. Final growth showed significant differences when using Colpoda culture as a starter feed, although this test resulted in the lowest survival rate (69%), indicating that further studies on the management of its culture should be undertaken to improve the applicability of the technique. The mean final survival rate was 83%.     

Effects of 645 MeV and 9.2 GeV protons on Artemia eggs.

Developmental capacities of Artemia eggs have been studied after exposure to 645 MeV or 9.2 GeV protons. Effects of proton irradiation were studied in comparison with 60Co gamma ray irradiation, endpoints being emergence, hatching and 4-5 day old live nauplii percentages. Effectiveness of 645 MeV protons is greater than that of 9.2 GeV protons. R.b.e. values calculated for nauplius survival is 2.3 for 645 MeV protons and 1.5 for 9.2 GeV protons. These results can be taken into account in radiation hazard estimation during space flights.     

Evaluation of the probiotics Bacillus subtilis and Lactobacillus plantarum bioencapsulated in Artemia nauplii against vibriosis in European sea bass larvae (Dicentrarchus labrax, L.)

Two potential probiotics Bacillus subtilis and Lactobacillus plantarum were evaluated for use in aquaculture as preventive measures against vibriosis. In vitro evaluation of the probiotics using co-culture assays with the pathogen Vibrio anguillarum and testing for the production of antibacterial substances showed the presence of antagonism and confirmed the production of antibacterial substances. Both potential probiotics were administered to the live fish feed Artemia franciscana nauplii, offering protection against a subsequent challenge of the nauplii with the fish pathogen V. anguillarum, with best survival rates of the nauplii and the most efficient protection offered by B. subtilis. Nauplii enriched with B. subtilis were further used to evaluate the protection of sea bass larvae against vibriosis. The untreated group of fish challenged with V. anguillarum presented low survival of 36.7 %, while the fish treated with nauplii enriched with the probiotic B. subtilis showed significantly increased survival rates of 86.7 % after challenge with the pathogen. The survival of healthy unchallenged fish treated with the probiotic was not significantly different from control unchallenged fish (90-94 %). Our results indicate that B. subtilis is a probiotic suitable to be used for the prevention of vibriosis in fish larvae and can be safely administered through their live feed Artemia nauplii.     

Variability of <Emphasis Type="Italic">Artemia salina</Emphasis> cysts from Sabkhet El Adhibet (southeast Tunisia) with special regard to their use in aquaculture

Brine shrimp Artemia (Crustacea, Anostraca) diverge in biometry and nutritional quality. These differences in Artemia characteristics are significant not only from strain to strain but also from one harvest to another within same strain. The main objective of this study was to compare Artemia salina cysts harvested from Sabkhet El Adhibet (southeast Tunisia) on different dates between 2002 and 2007 with special regard to their use in aquaculture, using cysts and naupliar biometrics, protein, carbohydrate, and lipid content. Fatty acid profiles as well as hatching characterisation were also evaluated. Hydrated cysts measures ranged between 258.1 and 263.7 μm, while the freshly hatched nauplii of Artemia measures ranged between 458.1 and 476.1 μm. Lipid contents of the samples ranged from 16.2 to 18.3% of the dry weight. Fatty acid profiles showed that cysts from Sabkhet El Adhibet contain a high quantity of eicosapentaenoic acid (20: 5n-3) with a percentage ranging between 7.8 and 14.3% of the dry weight. The highest hatching efficiency was obtained for decapsulated cysts collected in 2007 (139500 nauplii g⁻¹ of cysts). Cysts treated with hydrogen peroxide had a hatching percentage of 14.49 to 42.99%. The hatching synchronization time for untreated cysts varied between 23.5 to 27.4 h.     

High beta-hydroxybutyrate concentration in liver and skeletal muscle of newly hatched chicks

Characteristic changes in ketone body concentrations in blood, liver, and skeletal muscle were investigated in detail in newly hatched chicks. The concentration of beta-hydroxybutyrate in the blood was maximal at hatch (0 day), markedly decreased to 3 days, then maintained at low levels, up to 14 days of age. The concentration of acetoacetate in blood, on the other hand, did not change after hatching but remained lower than that of beta-hydroxybutyrate at all ages. In liver and muscles, the concentration of beta-hydroxybutyrate changed in a manner similar to that in the blood. The muscle to blood ratio of the beta-hydroxybutyrate concentration on days -1 and 0 was significantly higher than those at 1 through 14 days post-hatch. These results show that newly hatched chicks have the same high ketone body concentrations in the skeletal muscle, blood and liver. It is, hence, suggested that uptake of beta-hydroxybutyrate by muscles is substantial or that ketogenesis, if any, occurs in muscles immediately before and after hatching of chicks.     

Sibling cannibalism in dorada under experimental conditions.

Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When oered alternative fish prey [embryos of Prochilodus magdalenae (0·5–0·8 mg) and Oreochromis niloticus (9·10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing <10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day ⁻¹, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated eciently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species.     

Eclossion of cysts of two species of Dendrocephalus (Anostraca: Thamnocephalidae) of potential use as food in aquaculture

The use of Artemia salina nauplii as live food has significantly aided culture of commercial fish and shrimps in recent years. However, reported deficiencies in the nutritional value of some strains originated the study of freshwater fairy shrimps as an alternative to Artemia. This study presents cyst biometry for Dendrocephalus geayi and D. spartaenovae (Anostraca: Thamnocephalidae), and the effects of some physicochemical variables on cyst hatching. The biometric characteristics of D. geayi and D. spartaenovae are within the size range of commercial Artemia strains. Favorable conditions to hatch D. geayi are 30 degrees C and conductivity near that of distilled water (<5 micromhos). For D. spartaenovae, these conditions are 28 degrees C and 280 micromhos. A very low salinity such as 1 per thousand inhibits hatching in both species.     

4种生态因子对虎斑乌贼幼体生长与存活的影响

旨在研究温度、盐度、饵料种类、投饵量对虎斑乌贼（Sepia pharaonis）幼体生长与存活率的影响,以确定其生长发育的最佳生态条件,为人工育苗提供理论依据。在室内控制条件下,采用单因子试验研究了不同温度（18、21、24、27、30和33℃）、不同盐度（18、21、24、27、30和33）、不同饵料种类（虾糜、活糠虾、卤虫无节幼体、桡足类、死糠虾、虾糜＋强化卤虫后无节幼体、强化卤虫后无节幼体）、活糠虾不同投饵量（0、2、4、6、8和10 g/d）对虎斑乌贼幼体生长发育的影响。结果显示：不同温度对虎斑乌贼幼体生长影响显著（P〈0.05）,最适温度为24-27℃,在最适温度下,存活率为84.4%-91.1%,特定生长率为4.82%-6.13%,存活率（y）与温度（x）的函数关系为y=-0.15x3＋30.637x-447.002（r2=0.923）。幼体适宜盐度为24-33,最适盐度为27,在最适盐度条件下,其存活率为（90.0±5.29）%,特定生长率为（3.71±0.34）%。投喂7种开口饵料,以活糠虾效果最佳,存活率为（96.7±2.94）%,特定生长率为（3.77±0.23）%;强化卤虫后无节幼体效果次之,存活率为（95.6±2.31）%,特定生长率为（2.54±0.15）%,其余各组培养效果均不理想。投喂活糠虾,随着投饵量的增加,其存活率随之提高,摄食量（y）与个体重（x）的回归方程为y=0.227x-0.063（r2=0.921）。     

Uptake and processing of a Vibrio anguillarum bacterin in Artemia franciscana measured by ELISA and immunohistochemistry

Nauplii of Artemia franciscana were incubated in two different concentrations (undiluted and 1:9 in autoclaved sea water) of a divalent bacterin composed of two different serovars of Vibrio anguillarum. In order to investigate uptake and further processing of a bacterin in the live feed organism A. franciscana, immunohistochemistry was applied, visualising the presence of whole bacterial cells and antigens from the bacterin in individual nauplii. By using ELISA, it was shown that approximately 1.5-2-5 x 10(5) cells were incorporated into each Artemia under the conditions used. Maximum incorporation of cells was measured after 30 min, whereas after 60 min there was a decline to levels of 0.9-1.6 x 10(5) cells per Artemia. Immediately after incubation in the bacterin solution, the nauplii were transferred to a culture of the alga Isochrysis galbana, in order to simulate transfer of the nauplii to rearing tanks for fish larvae. From the ELISA, it could be concluded that the incorporated bacterial cells were excreted from the Artemia nauplii rapidly, however a large variation among different nauplii could be visualised by immunohistochemistry.     

Quality evaluation of brine shrimpArtemia cysts produced in Asian salt ponds

Artemia cysts produced in inoculated salt ponds in the Philippines, Thailand and India, were analyzed in comparison with the parental strains used for the inoculations. Cyst hatching efficiency, hatching rate and color changed significantly after inoculation, whereas the cyst's diameters, nauplius survival and nauplius growth remained fairly constant. The nutritional value of theArtemia nauplii was determined in a standard culture test withMysidopsis bahia juveniles as test animals. Production results were compared with the fatty acid profiles of theArtemia nauplii. Low levels of the essential fatty acid 20:53 in one of the produced cyst batches were probably caused by inadequate food conditions in the pond and resulted in poorer growth of theMysidopsis juveniles. Based on the results of this study a distinction is made between essential and nonessential strain selection-criteria forArtemia inoculations and transplantations.     

Developmental changes in poly(A) polymerase activity in Artemia

The levels of poly(A) polymerase activity have been determined during Artemia early development. Poly(A) polymerase activity increases steadily during postgastrular embryonic development reaching a maximum shortly after hatching. The rise of poly(A) polymerase is concomitant with an increase in poly(A) content and with a change in the subcellular distribution of the enzyme activity, the major increase corresponding to the nuclear fraction. Only one isoenzyme of poly(A) polymerase has been identified in Artemia embryos and nauplii despite changes in enzyme levels and subcellular changes during early development. Poly(A) polymerase is not associated with the cytoplasmic poly(A)-containing ribonucleoprotein particles stored in Artemia dormant embryos.