Dynamics of free amino acids in the hemolymph of Pacific whiteleg shrimp Litopenaeus vannamei exposed to different types of stress

We analyzed the dynamics of amino acids, ammonia-N, and carbohydrates in hemolymph when Pacific whiteleg shrimp Litopenaeus vannamei was subjected to air-exposure and low-salinity stresses. Glycine, l-arginine, and d- and l-alanine levels in hemolymph were increased under both stress conditions. Ammonia-N, a product of amino acid catabolism, also increased in level. These results suggest that the above-mentioned amino acids are used as energy sources. Levels of total carbohydrates, the sum of glucose and other carbohydrates, in the hemolymph showed different dynamics between the two types of stress and were not always high. This suggests that other energy sources, such as amino acids, are important when animals are subjected to stress. It is possible that particular amino acids act as energy sources under various stress conditions.     

Carotenoids and retinal levels in captive and wild shrimp, Litopenaeus vannamei

In farm‐raised marine organisms, the interactions and functions of carotenoid and retinoid micronutrients as free radical scavengers during specific physiological processes, such as gonadic maturation, are not known. Captive and wild female white shrimp, Litopenaeus vannamei, were sampled at two maturation stages: II and IV. Total carotenoids, a carotenoid profile, and vitamin A from the digestive gland and ovary were determined. Superoxide dismutase (SOD) activity was determined in hemolymph. The carotenoid concentration and range of activity were significantly higher (P < 0.05) in wild than in captive shrimp, particularly at maturation stage IV. Activity of SOD in hemolymph of captive shrimp at both stages of maturation was significantly greater (P < 0.05) than that of wild organisms. In sexually exhausted, level IV captive shrimp, low carotenoid concentrations, mainly in digestive gland and ovary, reflected scavenger action insufficient to neutralize oxidative stress processes, as suggested by SOD activity. Carotenoids are important nutrients associated with the reproductive capacity of shrimp.     

Pharmacokinetics of enrofloxacin and its metabolite ciprofloxacin in Pacific white shrimp <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis> after multiple-dose oral administration

The present study was designed to explore pharmacokinetics (PK) of enrofloxacin and its metabolite ciprofloxacin in Pacific white shrimp Litopenaeus vannamei after multiple-dose oral administration of enrofloxacin (30 mg/kg dose per 12 h and continuous feeding for 3 days). Enrofloxacin and ciprofloxacin concentrations in hemolymph, hepatopancreas, and muscle of the shrimp were simultaneously determined by high-performance liquid chromatography. PK parameters were analyzed based on statistical moment theory. Meanwhile, the relationship of pharmacokinetics/pharmacodynamics (PK/PD) was established based on drug concentration of hemolymph and in vitro antibacterial activity (MIC value). Results showed faster absorption of enrofloxacin in hemolymph (T_max?=?1 h) and muscles (T_max?=?1 h) than that in hepatopancreas (T_max?=?3 h) after the first oral administration. In multiple-dose oral administration, slight accumulation of enrofloxacin occurred in the hemolymph and hepatopancreas, while in the muscle, enrofloxacin concentration showed a significant decline following multiple administration. Tissue distribution of enrofloxacin and ciprofloxacin both followed the order hepatopancreas?>?hemolymph?>?muscle, with significantly higher ciprofloxacin concentration in hepatopancreas than in hemolymph (approximately 10-fold) and muscles (approximately 50-fold), indicating that the hepatopancreas is the main organ involved in metabolism of enrofloxacin in Pacific white shrimp. After multiple-dose administration, C_max/MIC and AUC_0–24/MIC values showed that the therapeutic regimen in this study could be remarkably effective in prevention and treatment of Vibrio infection in Pacific white shrimp.     

Protection of common carp (Cyprinus carpio L.) spermatozoa motility under oxidative stress by antioxidants and seminal plasma

The protective influence of seminal plasma and the antioxidants catalase (CAT), superoxide dismutase (SOD), and glutathione (GTH) on quality parameters, oxidative stress indices, and antioxidant activity was studied in common carp (Cyprinus carpio) spermatozoa exposed to the xanthine–xanthine oxidase (X–XO) system. Fish spermatozoa were incubated for 5 and 20 min at 4 °C with X–XO concentrations of 1 mM X–0.1 U/mL, 0.6 mM X–0.05 U/mL, 0.3 mM X–0.025 U/mL, and 0.1 mM X–0.0125 U/mL. A dose-dependent reduction in spermatozoa motility and velocity was observed at concentrations of 0.1 mM X–0.0125 U/mL to 1 mM X–0.1 U/mL XO. Increase in spermatozoa motility parameters was recorded following treatment with antioxidants and seminal plasma. The level of the oxidative stress indices lipid peroxidation (LPO) and carbonyl derivatives of proteins (CP) was significantly reduced after addition of CAT, SOD, or GTH along with seminal plasma. Significant differences in SOD, glutathione reductase, and glutathione peroxidase activity were seen in spermatozoa incubated with, compared to that without, seminal plasma at all studied X–XO concentrations. The data demonstrated that CAT, SOD, or GTH in combination with SP can reduce reactive oxygen species stress in fish spermatozoa and improve spermatozoa quality.     

Passive immunity in tiger shrimp (Penaeus monodon) fed with monoclonal antibody to white spot syndrome virus

A study was conducted on the stability of monoclonal antibody (MAb) in the hepatopancreas and hemolymph of Penaeus monodon and its effect on protection against white spot syndrome virus (WSSV) upon challenge. MAb C-5 raised against WSSV was purified and coated onto a commercial shrimp feed at dosages of 5, 10 and 15 mg/kg feed. The feed was fed to P. monodon and stability of the MAb in hepatopancreas and hemolymph was determined by immunodot and Western blot. Immunodot results indicated the presence of MAb for 2 h post-feeding in hepatopancreas and hemolymph which was dose-dependent. MAb was also detected in hemolymph by Western blot up to 1 h post-feeding. Shrimp fed with MAb were challenged with WSSV by oral and injection methods. In shrimp fed with 15 mg antibody/kg feed (0.45 μg MAb/g shrimp/day) WSSV infection significantly delayed both in oral and injection challenges with a survival of 65 and 70 % (p < 0.05), respectively, during 15 days post-challenge. MAb was stable in shrimp for passive immunization against WSSV and could be a potential tool for prophylaxis against the virus.     

Xanthine oxidase activity exerts pro‐oxidative and pro‐inflammatory effects in serum of silver catfish fed with a diet contaminated with aflatoxin B1

Several studies have associated the involvement of xanthine oxidase (XO) activity, a source of uric acid and reactive oxygen species (ROS), to pro‐oxidative and pro‐inflammatory effects during pathological conditions. Considering this, the aim of this study was to evaluate whether upregulation on seric XO activity may be a pathway involved in the oxidative stress in fish exposed to a diet contaminated with aflatoxin B₁ (AFB₁), as well as whether it may be considered a pathway involved in ROS and NOx production. Xanthine oxidase activity, as well as the uric acid, ROS and NOx levels increased in serum of fish fed with a AFB₁‐contaminated diet on days 14 and 21 post‐feeding compared to fish fed with a basal diet. Based on these evidences, upregulation of seric XO activity induces pro‐oxidant and pro‐inflammatory profiles in serum of fish fed with a AFB₁‐contaminated diet due to excessive formation on uric acid. Also, the excessive uric acid induces the release of pro‐oxidant and pro‐inflammatory mediators, as ROS and NOx, also contributing to oxidative and inflammatory profiles. In summary, the upregulation on seric XO activity may be considered a pathway involved in the oxidative stress of fish exposed to a diet contaminated with AFB₁.     

Dopamine induces transient modulation of the physiological responses of whiteleg shrimp,Litopenaeus vannamei

Levels of glucose, lactate, Na⁺, K⁺, Cl⁻, protein, and oxyhemocyanin in the hemolymph and its osmolality were measured when the whiteleg shrimp (Litopenaeus vanammei; 20 ± 1.5 g), were individually injected with saline or dopamine at 10^− 8, 10^− 7, or 10^− 6 mol shrimp^− 1. Results showed that elevations of hemolymph glucose and lactate occurred at between 2 and 4 h, increases in hemolymph osmolality, Cl⁻, Na⁺, and total protein occurred at 2 h, and a reduction in hemolymph oxyhemocyanin occurred at 4 h after the dopamine injection. All physiological parameters except K⁺ had returned to the control values 8–16 h after receiving the dopamine. The injection of dopamine also significantly decreased the oxyhemocyanin/protein ratio of L. vannamei at 2 h as a result of the elevation of hemolymph protein. These results suggest that stress-inducing dopamine causes a transient period of modulation of energy metabolism, osmoregulation, and a respiratory response in L. vannamei in adapting to an environmental stress.     

Effects of cold acclimation on the survival,feeding rate,and non-specific immune responses of the freshwater red claw crayfish (<Emphasis Type="Italic">Cherax quadricarinatus</Emphasis>)

The effect of cold acclimation on growth performance, non-specific immune responses, and expression level of HSP21 and CSP gene were studied in red claw crayfish (Cherax quadricarinatus) using a 4-week stress trial. We set a four-temperature gradient, with water temperatures of 25, 20, 15, and 9 °C, respectively. With the gradual decrease of temperature, the survival rate, feeding rate, and hepatopancreas index (HIS) of the red claw crayfish showed a decreasing trend. Decreased total hemocyte count (THC) and hemocyanin concentration were observed when water temperature decreased. The activities of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in the hepatopancreas and hemolymph all gradually declined with decreasing temperatures and then significantly lowered at 9 °C compared with those at 25 °C. The activity of glutathione peroxidase (GPx) in these two tissues showed in the opposite trend, indicating that they may have different regulation mechanisms. A gradual increase of malondialdehyde (MDA) concentration was detected in the hepatopancreas and hemolymph when the temperature decreased. Low temperature stress also affected the expression of heat shock proteins 21(HSP21) and cold shock domain protein (CSP). These results indicate that cold acclimation may induce oxidative stress on the crayfish and then cause oxidative damage and hemocyte apoptosis, as well as immunosuppression in Cherax quadricarinatus, which may finally affect the growth and survival of Cherax quadricarinatus.     

The ex vivo effects of eyestalk peptides on ovarian vitellogenin gene expression in the kuruma prawn Marsupenaeus japonicus

Seven major peptides belonging to the crustacean hyperglycemic hormone family were purified from the sinus gland located in the eyestalk of the kuruma prawn Marsupenaeus japonicus, and their effects on vitellogenin gene expression were examined using the ex vivo ovary incubation system. Six molecular species of crustacean hyperglycemic hormone, Pej-SGP-I, -II, -III, -V, VI, and VII, displayed significant inhibitory effects on vg expression with almost the same efficacies, whereas Pej-SGP-IV (known as molt-inhibiting hormone) did not. Two chromatophorotropic peptides, red pigment-concentrating hormone and pigment-dispersing hormone, which were also present in the sinus glands, did not have a clear effect on the gene expression levels in this incubation system. These results suggest that the six crustacean hyperglycemic hormones are potentially capable of acting as vitellogenesis-inhibiting hormones in M. japonicus.     

中华绒螯蟹血淋巴内盐酸环丙沙星的反相高效液相色谱法的建立

应用反相高效液相色谱法(RP-HPLC)建立了盐酸环丙沙星在中华绒螯蟹血淋巴内含量的测定方法.本法采用肌肉注射的给药方法,给药剂量为8.17±0.56mg·kg-1和6.25±0.85mg·kg-1.血淋巴从心区抽取.经各种抗凝方法的比较,认为等量的ACD与等量的血淋巴混合,可得到持久的抗凝效果.血淋巴样经甲醇去蛋白,3000r/min离心10min后,取上清液上HPLC.色谱柱,RP-ODS-5μl50×4.6mm;流动相,甲醇-磷酸缓冲液-四丁基溴化铵=25075020(v/v/v);流速,l mL·min-1;进样量,2μL;检测波长,280nm.研究表明,本法线性关系与重复性良好;雌、雄蟹平均回收率分别为100.08±3.43%和99.11±8.20%;日间精密度、平均提取精密度分别为1.19±0.92%、1.55±0.01%.用该方法对肌肉注射给药后48h内中华绒螫蟹雄蟹血淋巴中的盐酸环丙沙垡的血药浓度进行检测,揭示出由37.13±0.08μg·mL-1降至5.96±0.18μg·mL-1的代谢规律.     

中华绒螯蟹血淋巴和肝胰腺的总蛋白含量与性早熟的关系

中华绒螯蟹扣蟹性腺发育与肝胰腺和血淋巴的蛋白质浓度相关.性早熟前后,雌雄扣蟹肝胰腺总蛋白浓度分别由(121.17±44.50)mg@g-1和(89.43±21.86)mg@g-1下降至(81.08±5.84)mg@g-1和(70.58±9.90)mg@g-1,雌性扣蟹的肝胰腺占体重的比值也由8.18%降至3.90%.血淋巴总蛋白浓度正常发育的雌性扣蟹为(99.55±12.06)mg@mL-1,明显高于性早熟雌性扣蟹的(72.26±17.87)mg@mL-1;而雄性扣蟹性早熟前后的血淋巴总蛋白浓度无显著差异.肝胰腺总蛋白浓度二秋龄雌蟹高于性早熟雌性扣蟹,但它们之间的血淋巴总蛋白浓度没有显著差异.二秋龄雄蟹的血淋巴和肝胰腺总蛋白浓度与性早熟雄性扣蟹相当,差异不显著.     

Effect of lignite fulvic acid on growth,antioxidant ability,and HSP70 of Pacific white shrimp, <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

This study was conducted to evaluate the effects of fulvic acid (0, 0.3, 0.6, 0.9, and 1.2%) as feed additive on growth, feed utilization, antioxidant ability, and HSP70 in hemolymph and hepatopancreas of juvenile white shrimp Litopenaeus vannamei (average weight 2.5 g) reared under experiment conditions. Shrimp were stocked at a density of 625 shrimps m^?3 for 60 days in net cages submerged in recirculating tanks. At the end of the experiment, specific growth rates and survival rates of shrimp in treatment groups fed with 0.6, 0.9, and 1.2% fulvic acid were higher compared to that of the control group. Shrimp fed 0.6, 0.9, and 1.2% fulvic acid had significantly lower feed conversion rates than those fed control diet. The optimum dietary fulvic acid requirement for juvenile shrimp based on weight gain was 0.897%. Furthermore, superoxide dismutase activity and peroxidase activity increased significantly, while malonaldehyde content decreased in the hemolymph and hepatopancreas of shrimp fed 0.9 and 1.2% dietary fulvic acid. Glutathione content increased obviously in hemolymph of shrimp fed 0.6, 0.9, and 1.2% fulvic acid. In hepatopancreas, glutathione content was significantly higher in shrimp supplemented with 1.2% fulvic acid. HSP70 decreased obviously in hemolymph of shrimp fed 0.9 and 1.2% fulvic acid, while shrimp fed with 0.6 and 0.9% fulvic acid showed lower HSP70 level in hepatopancreas. The results of this study demonstrated that dietary fulvic acid could improve survival rates, growth, feed utilization, antioxidant capability, and stress resistance of juvenile L. vannamei reared under intensive stocking conditions.     

Cortisol is responsible for positive and negative effects in the ovarian maturation induced by the exposure to acute stressors in Nile tilapia, Oreochromis niloticus

The aim of the present study was to evaluate the effect of acute stress and cortisol injection on oocyte final maturation process in female Nile tilapia (Oreochromis niloticus). Handling followed by a prophylactic treatment (0.3?mL?L^?1 H₂O₂, 5?g?L^?1 NaCl solution during 30?min) and an environmental change (transfer from a 2?m³ fibreglass square tank to 50?L aquaria) were used as acute stressors and compared to a single cortisol injection (0.5 or 5?mg?kg^?1 body weight). For both acute stress and cortisol injection (0.5?mg?kg^?1 body weight), serum cortisol level was significantly increased from 2.3 to 134.1?ng?mL^?1 1?h post-stress/injection and returned to a resting basal value 24?h after the stress/injection. In fish injected with 5?mg?kg^?1 body weight cortisol, mean serum cortisol level reached a peak up to 2500?ng?mL^?1 1?h after injection. 63?% of the females (mean body weight: 242?±?4?g) submitted to the acute stress ovulated within 72?h after the stress. In the same way, cortisol injection (5?mg?kg^?1 body weight) at the 10th day of the maturation cycle led to a twofold reduction of the time before ovulation compared to vehicle injected control fish. Relative and total fecundity were significantly decreased in females submitted to an acute stress or cortisol injected at 5?mg?kg^?1 body weight, but not fertilization or hatching rates. In conclusion, acute stress and cortisol induction exert both positive and negative effects on the final reproductive process in O. niloticus, and cortisol is the endocrine mediator causing these changes.     

Immunogene expression in head kidney and spleen of common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) following thermal stress and challenge with Gram-negative bacterium, <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis>

To evaluate the effect of thermal and microbial stress on the immune response of common carp (Cyprinus carpio L.), relative mRNA expression level of pro-inflammatory cytokines [tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β] and other genes related to immune or stress response [inducible nitric oxide synthase (iNOS), heat shock protein 70 (Hsp70), superoxide dismutase one (SOD1), and glucocorticoid receptor (GR)] was measured by quantitative PCR (qPCR). In addition, total protein and total immunoglobulin level in blood plasma of experimental common carp was also assayed. All the above parameters were estimated 24 h post-challenge with Gram-negative bacterium, Aeromonas hydrophila. Common carp (54.89?±?6.90 g) were initially exposed to 20 °C (control group) and 30 °C (thermal stress group) water temperature for 30 days, followed by experimental challenge with 2.29?×?10⁸ colony forming unit/mL (CFU/mL; LD₅₀ dose) of A. hydrophila. Exposure of fish to thermal stress and subsequently challenge with A. hydrophila significantly (P?<?0.05) increases the IL-1β mRNA expression in head kidney and spleen of common carp by ~?39.94 and ~?4.11-fold, respectively. However, TNF-α mRNA expression in spleen decreased ~?5.63-fold in control fish challenged with A. hydrophila. Thermal stress and challenge with bacterium suppresses the iNOS and GR mRNA expression in spleen of common carp. Moreover, significant (P?<?0.05) increase in total protein content of blood plasma (~?43 mg/g) was evident in fish exposed to thermal stress and challenged with A. hydrophila. In conclusion, our study highlights the importance of elevated temperature stress and microbial infection in differential regulation of expression of several immunogenes in common carp.     

近江牡蛎HSC70基因对溶藻弧菌感染的反应

人工注射溶藻弧菌(Vibrio alginolyticus)感染近江牡蛎(Crassostrea hongkongensis),通过实时荧光定量RT-PCR方法检测了近江牡蛎6种不同组织器官(外套膜、鳃、消化腺、闭壳肌、心脏和血细胞)中HSC70基因表达量的变化;同时采用平板活菌计数法测定了近江牡蛎不同组织器官中溶藻弧菌菌量的变化。结果显示,人工注射感染溶藻弧菌后,近江牡蛎6种组织器官中HSC70基因表达量均显著性升高(P<0.05),且随时间变化均呈现出先升高后恢复至对照水平的趋势;其中鳃组织中HSC70基因分别在第6小时和第72小时出现2次显著性高表达,且在第72小时的表达量高于第6小时(P<0.05)。在多数组织器官中,HSC70基因出现显著高表达后便急剧下降至对照水平,而在消化腺中高表达持续的时间长达18 h(第6 24小时)。在注射感染溶藻弧菌后第6小时,血细胞中HSC70基因的表达量达到峰值,接近于对照水平的15倍;而在其他组织器官中,该基因表达峰值仅为对照水平的2.5倍左右。人工注射感染溶藻弧菌后3 h,3种组织(消化腺、闭壳肌和血淋巴)中均能检测到溶藻弧菌的积累,其中闭壳肌中含菌量最高,6 h时闭壳肌中含菌量急剧下降,随后又增加并维持在一定水平直至72 h;消化腺中菌量随着时间推移而增加,到达峰值后又逐步下降;血淋巴中,溶藻弧菌含量整体上随时间不断增加,到48 h稳定在较高水平。各组织中HSC70表达量与溶藻弧菌含量之间存在一定的关联性,尤其在溶藻弧菌攻击的靶器官(消化腺)中最为明显。由此可见,病原菌感染可以诱导近江牡蛎HSC70基因高表达,并且HSC70可能参与了机体抗病原菌感染的相关作用,这为进一步研究近江牡蛎HSC70基因在抗病免疫中的作用机制奠定了基础。     

Naltrexone attenuates stress-induced suppression of LH secretion in the pituitary gland in the Cichlid fish Oreochromis mossambicus: evidence for the opioidergic mediation of reproductive stress response

Opioid peptide β-endorphin (β-EP) plays a modulatory role in vertebrate reproduction. However, the role of opioid peptides in reproductive stress response is least understood in fishes. The aim of the present study was to determine the effect of different doses of β-EP on luteinizing hormone (LH) secretion in normal and the opioid receptor antagonist naltrexone (NALT) in stressed female tilapia Oreochromis mossambicus. Administration of 4 μg β-EP, but not 0.5 or 1.5 μg β-EP, daily for 22 days caused suppression of LH-secreting cells at the proximal pars distalis of the pituitary gland, concomitant with a significant reduction in the mean GSI and HSI in 4 μg β-EP-treated fish compared to controls. On the other hand, exposure of the fish to mild acute stressors for 22 days caused changes in the LH-secreting cells similar to that of high dose of β-EP, whereas administration of NALT attenuated these effects. Taken together, the results indicate that increased concentration of β-EP as may occur during stressful conditions can cause suppression of LH secretion, leading to the inhibition of spawning, and that treatment of NALT attenuates the stress-induced inhibition of LH secretion in fish.     

Pharmacokinetics and bioavailability of oxytetracycline in vannamei shrimp (Penaeus vannamei) and the effect of processing on the residues in muscle and shell

The present study examined the pharmacokinetics and bioavailability of oxytetracycline (OTC) in vannamei shrimp (Penaeus vannamei) after intra-sinus (10 mg/kg) and oral (10 and 50 mg/kg) administration and also investigated the net changes of OTC residues in the shrimp after the thermal, acid and alkaline processing methods. The hemolymph concentrations of OTC after intra-sinus dosing were best described by a two-compartment open model. The oral bioavailability was found to be 48.2 and 43.6% at doses of 10 and 50 mg OTC/kg, respectively. The peak hemolymph concentrations after 10 and 50 mg OTC/kg doses were 3.37 and 17.4 μg/ml; the times to peak hemolymph concentrations were 7 and 10 h. The elimination half-lives were found to be 15.0 and 11.5 h for the low and high dose, respectively. The residual OTC was rapidly eliminated from muscle with the elimination half-life value of 19.4 and 15.4 h, respectively, for the groups treated with doses of 10 and 50 mg/kg. The residual OTC levels in the muscle fell below the MRL (0.2 μg/g) at 72 and 96-h post-dosing at dose levels of 10 or 50 mg/kg, respectively. Residual OTC levels in muscle and shell were approximately 20–50% lower in the thermal treatment such as boiling, baking and frying. By the acid treatment, OTC residues were reduced to >80%, while those were reduced to around 30% by alkaline treatment.     

中国对虾肝胰腺_卵巢及血淋巴中的_省略_雌二醇含量的生殖周期变化

首次证实了孕酮和雌二醇这两种类固醇激素在中国对虾体内的存在.在性腺未发育阶段,肝胰腺、卵巢和血液中两种激素的含量均很低氐,难以检测到.而在卵黄发生前期(核仁周边期),三种组织中孕酮和雌二醇含量迅速上升,卵巢的雌二醇含量达到高峰(450.1±86.7).进入初级卵黄发生阶段,三种组织中,两种激素均具较高含量,卵巢和肝胰腺的孕酮含量(分别为1975 1±175.2和902.6±130.5pg/g)以及血淋巴中的雌二醇含量(451.3±73.7)达到高峰.到了次级卵黄发生阶段,孕酮和雌二醇的含量迅速下降,肝胰腺等组织中儿乎检测不到.对虾性腺指数(GSl)的增长既显著且有规律性,每一期增长幅度都达到或超过l00%.肝胰腺指数(HSI)从性腺未发育期(3.4±04)到卵黄发生前期(4.9±0 7)以及从卵黄发生前期到初级卵H黄发生期(6.3±1.0)有显著的增长,而从初级卵黄发生期到次级卵黄发生期HSI增长不显著(6.7±1.2).肝胰腺指数的增长与两种类固醇激素含量的变化具相似的趋势.上述结果显示,孕酮和雌二醇可能具有刺激和凋控中国对虾性腺发育的作用,肝胰腺可能是卵黄蛋白原的合成场所.     

Isolation and characterization of an additional crustacean hyperglycemic hormone from the greasyback shrimp <Emphasis Type="Italic">Metapenaeus ensis</Emphasis>

Crustacean hyperglycemic hormone (CHH) is released from the X-organ/sinus gland complex located in the eyestalks. In this study, the most abundant CHH in the sinus gland of the greasyback shrimp Metapenaeus ensis was purified by reversed-phase HPLC and identified by N-terminal amino acid sequencing. Although two CHH molecules (Mee-CHH-A and Mee-CHH-B) have already been identified from M. ensis by cDNA cloning, this study revealed the presence of an additional CHH peptide based on differences in the N-terminal amino acid sequences of the CHH-A and CHH-B. Therefore, this novel CHH was designated as Mee-CHH-C. A cDNA encoding the Mee-CHH-C precursor was cloned by RT-PCR coupled with 5′- and 3′-RACE, and it was found that the mature Mee-CHH-C consisted of 72 amino acid residues containing 6 conserved cysteine residues and possessed an amidated C terminus. Mee-CHH-C had 62 and 68% identities with Mee-CHH-A and Mee-CHH-B, respectively, and was highly homologous to CHHs characterized from other penaeid shrimp species. The hyperglycemic activity of Mee-CHH-C was examined by an in vivo bioassay using the kuruma prawn Marsupenaeus japonicus. Injection of Mee-CHH-C increased hemolymph glucose levels significantly and dose-dependently. These results indicate that Mee-CHH-C is possibly one of the major molecules in M. ensis that regulate glucose levels in the hemolymph.     

Hemolymph Metabolic Variables in Response to Experimental Manipulation Stress and Serotonin Injection in Penaeus vannamei

Abstract— The effects of serotonin (5-HT) and the stress of repeated sampling on Penaeus vannamei hemolymph levels of glucose, lactate, triacylglycerol, cholesterol, and total protein were examined. For this purpose, a baseline hemolymph sample was taken and then shrimp were injected with 5-HT (50 μg/shrimp) or saline after which repeated individual samples were taken at 30, 60, and 120 min. Glucose levels tripled in both saline- and serotonin-treated shrimp when compared to baseline values, without any difference between both groups. In contrast, lactate level rose significantly only in the 5-HT group. The levels of this metabolite were significantly higher than in the salineinjection group for all time points. Triacylglycerol decreased in both groups and no substantial differences were observed in cholesterol and protein levels. The results indicate that repeated sampling stress produces strong hyperglycemia and that 5-HT does not produce an additional increase in glucose levels. However. this monoamine strongly increased lactate levels, a response that can be distinguished from stress and probably attributed to glycolysis.