饥饿对拟穴青蟹大眼幼体和Ⅰ期仔蟹蜕皮和生长的影响#br#

为了给拟穴青蟹(Scylla paramamosain)苗种培育过程中饵料的合理投喂提供基础理论数据,采用投喂-饥饿和饥饿-投喂的处理方式对拟穴青蟹大眼幼体和Ⅰ期仔蟹分别开展营养储存饱和点实验(PRS)和不可恢复点实验(PNR),研究饥饿对大眼幼体和Ⅰ期仔蟹蜕皮和生长的影响。结果显示,大眼幼体的PRS实验中,投喂时间≤2 d时,大眼幼体的蜕皮率为0;投喂时间≥4 d时,大眼幼体的蜕皮率和发育时间与连续投喂组(F组)无显著性差异;但投喂4 d-饥饿组(F4S组)大眼幼体蜕皮后Ⅰ期仔蟹的增重率和个体大小均显著小于F组(P<0.05)。大眼幼体的PNR实验中,饥饿2 d时大眼幼体的存活率仅为(30.00±13.23)%。Ⅰ期仔蟹的PRS实验中,连续饥饿组(S组)Ⅰ期仔蟹的蜕皮率为0,而投喂2 d-饥饿组(F2S组)、投喂3 d-饥饿组(F3S组)和F组3组Ⅰ期仔蟹的蜕皮率均无显著性差异。投喂1 d-饥饿组(F1S组)和F2S组Ⅰ期仔蟹蜕皮后Ⅱ期仔蟹的增重率和个体大小均显著小于F组(P<0.05),且F1S组Ⅰ期仔蟹的发育时间显著延长(P<0.05)。Ⅰ期仔蟹的PNR实验中,除饥饿1 d-投喂组(S1F组)外,F组Ⅰ期仔蟹的蜕皮率显著高于其他处理组(P<0.05);各组Ⅰ期仔蟹蜕皮后Ⅱ期仔蟹的增重率与饥饿时间呈负相关,而发育时间却与饥饿时间呈正相关;饥饿时间≥2 d时,Ⅰ期仔蟹蜕皮后Ⅱ期仔蟹的个体大小明显变小。拟合分析结果显示,大眼幼体的PRS;值是3.57 d,Ⅰ期仔蟹的PRS;和PNR;值分别是0.90 d和2.01 d。研究结果表明,新蜕皮的大眼幼体必须给予充足的饵料才可确保高的存活率,大眼幼体投喂6 d后可以适当减少投喂量,短期饥饿对Ⅰ期仔蟹蜕壳和生长的影响相对较小,Ⅰ期仔蟹的耐饥饿能力强于大眼幼体。     

饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分和消化酶活性的影响

用蛋白质水平分别为31.45%,36.37%,41.55%,46.13%,51.72%和56.86%的6种等能饲料,对初始体重为(11.86?0.11)mg的拟穴青蟹(Scylla paramamosain)幼蟹进行为期3周的养殖实验,考察饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分以及消化酶活性的影响,以期获得拟穴青蟹幼蟹饲料蛋白质的适宜添加量。结果表明,饲料蛋白质水平对拟穴青蟹幼蟹的成活率影响不显著(P0.05);幼蟹的增重率和特定生长率随饲料蛋白质水平的提高先显著升高(P0.05)后稍有下降,最大值出现在蛋白质水平为51.72%的实验组;随着饲料蛋白质水平的提高,幼蟹粗蛋白质含量显著升高(P0.05)后趋于稳定,粗脂肪含量显著降低(P0.05),灰分含量先显著升高(P0.05)后显著降低(P0.05),水分含量则没有显著变化(P0.05);随着饲料蛋白质水平的提高,幼蟹蛋白酶活性显著升高(P0.05),淀粉酶活性显著降低(P0.05),各组脂肪酶活性也有显著差异(P0.05),但没有明显的变化规律。本研究条件下,饲料蛋白质水平在41.55%~56.86%,拟穴青蟹幼蟹均表现出较好的生长率,增重率和蛋白质水平的回归分析表明,幼蟹饲料蛋白质适宜水平为49.03%。     

Development of nursery culture techniques for the mud crab Scylla paramamosain (Estampador)

Cannibalism is one of the main causes of mortality in the culture of the mud crab Scylla paramamosain, particularly in the early post‐larval and juvenile stages when the densities of hatchery‐reared crabs may be very high before stocking into ponds or release into the wild for stock enhancement. In a series of experiments investigating cannibalism mitigation, the influence of stocking density, the effectiveness of sand substrate, brick and shell shelters and feed type were compared in culture of crabs from instar 1 for short nursery periods of 15–30 days. Inclusion of brick and shell shelters significantly increased survival over sand substrate alone. However, inclusion of shelters did not affect growth rates. In scaled‐up nursery production in lined‐ponds, with shelters, live Artemia biomass and fresh chopped shrimp or tilapia were found to be equally effective feeds for juvenile crabs stocked at a density of 70 m⁻² from instar 1 and grown for 30 days [52–66% survival, 21.6–24.6 mm carapace width (CW)]. In an extended nursery period for a further 30 days, crabs of 22 mm CW, stocked at 30 m⁻² in the same ponds, attained a final size of 34.5–36.2 mm CW with a survival of 64.3–67.0% using the same feeds.     

拟穴青蟹vasa基因cDNA的特征分析与性腺特异表达

vasa蛋白属于DEAD家族蛋白,是一种RNA解旋酶,在生殖细胞的分化中具有重要作用。本研究从拟穴青蟹卵巢中克隆得到vasa基因cDNA全长(将其命名为Sp-vasa),Sp-vasa序列长度为2 944 bp,其中开放阅读框(ORF)长度为1 899 bp,编码632个氨基酸,具有DEAD-box家族蛋白的7个高度保守的结构域。半定量RT-PCR结果显示,Sp-vasa只在卵巢和精巢中特异表达,在其它组织则未检测到表达。由此可见,vasa属于拟穴青蟹性腺特异表达基因。因此,Sp-vasa基因可有望作为有效的分子指标研究拟穴青蟹原始生殖细胞的起源、迁移以及生殖腺的发生。     

Effects of Artemia enriched with eicosapentaenoic and docosahexaenoic acid on survival and occurrence of molting failure in megalop larvae of the mud crab Scylla serrata

ABSTRACT:   The present study was conducted to investigate the effect of eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) on the survival and the occurrence of molting failure to megalops of mud crab Scylla serrata larvae fed enriched Artemia . Survival rate, intermolt period, carapace width at the first crab stage, ratio of chela to carapace length at the fifth zoeal stage and the occurrence of molting failure to megalops were observed. Mud crab larvae were reared in 1-L plastic beakers and fed with Artemia enriched at five different levels of EPA (0.31% to 1.36% EPA; referred to as E25, E50, E75 and E100) or four different levels of DHA (0.75–0.95% EPA and 0.49–1.38% DHA; referred to as D25, D50, D75 and D100). As a negative control, larvae were fed Artemia enriched with oleic acid (OA). Mud crab larvae fed Artemia containing low (0.41–0.45% EPA and trace DHA) or high (1.36% and 0.95% EPA and 0.16% and 1.38% DHA) amounts of EPA and DHA showed a significantly lower survival rate and prolonged intermolt period ( P  < 0.05). Moreover, a high frequency of molting failure to the megalops stage (34 and 33%) occurs coincident with a high chela to carapace length ratio (43 and 44%) in mud crab larvae fed high amounts of EPA and DHA (E100 and D100), suggesting that both of these treatments contain EPA and DHA in excess. These results indicate that during Artemia feeding, EPA and DHA content should be adjusted to 0.71–0.87% and 0.49–0.72% for maintaining a high survival, accelerating the intermolt period, and producing larger carapace width in the first crab stage.     

拟穴青蟹ANT2基因在不同温度和盐度条件下的应激表达

采用qRT-PCR技术, 对不同温度(10℃, 15℃, 20℃, 25℃)以及低温(10℃, 15℃)和盐度(10, 35)联合作用下拟穴青蟹(Scylla paramamosain)(甲壳长3.7~5.8 cm, 体质量80~100 g) ANT2基因的表达进行了检测。结果表明: 在4个温度下肝胰腺、肌肉、鳃中ANT2基因表达量依次为低、中、高, 存在组织表达特异性。随着温度降低, ANT2基因总体上趋低表达, 但在15℃时ANT2基因在肌肉(1~12 h)和鳃中均显著高于20℃(P<0.05)。该结果提示, ANT2基因与能量代谢相关, 且在一定低温下被诱导表达, 可能参与低温胁迫的应答。相同低温下, 3种组织中ANT2基因在盐度10的表达量通常高于盐度35的(P<0.05), 说明低温下低盐环境有利于提高青蟹体内代谢, 增强耐寒能力。     

Induced out-of-season spawning of the mud crab, Scylla paramamosain (Estampador) and effects of temperature on embryo development

Treated with combined bilateral eyestalk ablation and maintenance of water temperature at 22.5±1.5 °C, mud crab Scylla paramamosain females with mature ovaries were induced to produce eggs outside the natural spawning season in subtropical southern China. Newly extruded eggs from a crab were incubated in vitro at 10, 15, 20, 25, 27, 30, 35 °C, respectively, and the embryonic development was closely monitored. Abnormal cell division was observed at temperatures 10 and 35 °C. At 15 °C, development remained at the gastrula stage by day 32 post‐spawn, at which time the experiment was terminated. Hatching of in vitro incubated eggs occurred between 20 and 30 °C. An increase in incubation temperature from 20 to 25 °C reduced the incubation duration by 14 days, 2.6 times of that measured for a similar 5 °C increase from 25 to 30 °C. Embryonic development of S. paramamosain was divided into stage 0–10, and the duration of each stage was recorded for each incubation temperature. The information obtained allows accurate prediction of hatching time of female crabs incubated under variable temperatures. Larvae hatched from in vitro incubated eggs were reared to reach first juvenile crab stage and their dry weights were similar to those of larvae hatched naturally.     

Effects of dietary phospholipids levels on growth performance,lipid metabolism,and antioxidant capacity of the early juvenile green mud crab,Scylla paramamosain (Estampador)

Four iso‐nitrogenous and iso‐lipidic diets were designed to investigate the effects of dietary phospholipids (PL) levels (with 0%, 1%, 2%, and 4% PL supplementation) on growth performance, lipid metabolism, and antioxidant capacity in early juvenile green mud crab (Scylla paramamosain). There were three replicates of 28 crabs (initial body weight from 42.02 to 42.44 mg) for each diet treatment, and growth trial lasted for 8 weeks. At the end of the growth trial, there was no significant difference in survival among all treatments. Crabs fed diet with 2% PL obtained highest weight gain (WG) and specific growth rate than other crabs. The molting frequency was not affected by different dietary PL addition. Besides, the contents of whole body lipid and long chain highly unsaturated fatty acids significantly increased with elevating dietary PL levels. In the hepatopancreas, crabs fed diet with 0% PL had significantly higher malondialdehyde concentration than other crabs. And crabs fed diet with 2% PL obtained significantly higher superoxide dismutase activity than crabs fed diets with 0% and 4% PL. Moreover, the mRNA expression of Na⁺/K⁺‐ATPase was significantly down‐regulated with dietary PL supplementation over 2%. Based on the second order polynomial regression analysis of WG, 2.37% dietary PL level was the optimal demand for early juvenile S. paramamosain. Moreover, we found crabs fed diet with 2% PL obtained better antioxidant capacity than other crabs.     

光照强度对拟穴青蟹幼体生长及能量收支的影响

以拟穴青蟹为研究对象,研究了1 000 lx、3 000 lx、5 000 lx、7 000 lx、9 000 lx五组光照强度对其溢状幼体蜕皮、生长及能量收支的影响.结果表明:(1)1 000 lx试验组幼体从第4期潘状幼体(Z<,4>)阶段起即期变态成活率明显下降,全部实验幼体最终均不能变态为大眼幼体(M);5 0...     

Comparative performance of hatchery-reared and wild Scylla paramamosain (Estampador, 1949) in pond culture

The performance of hatchery‐reared juveniles either in aquaculture grow‐out systems or stock enhancement is likely to be dependent on a range of factors during the hatchery phase of production. With recent progress in the development of hatchery systems for the mud crabs Scylla spp., there is growing interest in evaluation of the quality of hatchery‐reared juveniles relative to wild seed crabs as currently used in aquaculture. Hatchery‐reared and wild‐collected Scylla paramamosain juveniles were stocked either together in ponds or separately. All crabs were tagged with microwire‐coded tags, so that origin could be determined in the mixed groups. Preliminary validation demonstrated that tagging did not affect survival or growth, with a tag retention of 94%. After 106 days of culture, there was no significant difference in survival at harvest between the two sources of crabs. The wild juvenile crabs had a significantly higher initial weight:carapace width (CW) ratio compared with those from the hatchery, indicating a difference in condition. However, where crabs were stocked separately, the hatchery‐reared animals exhibited significantly faster growth than those collected from the wild, both in terms of specific growth rate and CW increase per month. However, in the mixed ponds, where there was competition with wild crabs, there was no significant difference in growth rate between crabs from the two sources. Overall, the results demonstrate that the growth performance of hatchery‐reared S. paramamosain can at least equal that of wild‐collected seed crabs in ponds culture.     

Influence of highly unsaturated fatty acids in live food on larviculture of mud crab Scylla paramamosain (Estampador 1949)

Two experiments were carried out to investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA) levels in rotifers (Brachionus plicatilis) and Artemia on the survival, development and metamorphosis of mud crab Scylla paramamosain larvae. Five different lipid emulsions, varying in the level of total n‐3 and n‐6 highly unsaturated fatty acids (HUFA), DHA, EPA and ARA were used to manipulate the fatty acid profile of the live food. Fatty acid profiles of the live food and crab larvae at zoea one, three and five stages were analysed to study the HUFA uptake by the larvae. The fatty acid content of the live food affected the fatty acid profiles of the crab larvae. In both experiments, the survival rate in the zoeal stages was not statistically different among treatments. However, larval development rate and metamorphosis success were affected by the dietary treatments. In this respect, the DHA/EPA ratio in the live food seems to be a key factor. Enrichment emulsions with a very high (50%) total HUFA content but a low DHA/EPA ratio (0.6), or zero total HUFA content caused developmental retardation and/or metamorphosis failure. An emulsion with a moderate total HUFA (30%) and a high DHA/EPA ratio (4) was the best in terms of larval development during the zoeal stages and resulted in improved metamorphosis. Dietary ARA seemed to improve first metamorphosis, but its exact role needs further clarification. For the larval rearing of S. paramamosain, an enrichment medium containing about 30% total n‐3 HUFA with a minimum DHA/EPA ratio of 1 is recommended. Further investigation is needed on the total HUFA and optimum DHA/EPA ratio requirements for each crab larval stage.     

Reproductive performance and offspring quality in mud crab (Scylla paramamosain) broodstock fed different diets

A 2-month feeding trial was conducted toevaluate the reproductive performance andoffspring quality of mud crab (Scyllaparamamosain) females fed either a mixture offresh food items (squid, shrimp, trash fish andArtemia biomass) or two experimentaldiets developed for penaeids. Before testinitiation, mud crab females with an averageindividual wet weight of 200–300 g wereacclimated for 2–3 days and reared together inone concrete tank of 2.0 × 0.5 × 8 m untilspawning. After spawning, the spent spawnerswere unilaterally eyestalk ablated and randomlydivided (20 animals/treatment) over three tanksof the same size and subjected to the dietarytreatments. Spent spawners were used toeliminate the effect of feeding history.There were only minor differences inreproductive performance between dietarytreatments. No differences were observed in theduration of the latency period from eyestalkablation to spawning. Fecundity was onlymarginally higher for the broodstock fed thecontrol diet. Also egg quality seemed onlyslightly affected by the treatments. Egghatching rates were slightly higher in crabsfed the formulated diets compared to thosecrabs fed the fresh diet. The onlystatistically significant difference (p < 0.05) observed however was in egg hatchingrate between the control diet and diet A2. Incontrast, the crabs fed the fresh diet producedstronger larvae as determined by a starvationtest.We therefore conclude that artificial dietsresulted in reproduction success comparable tothe use of fresh food. The nutritionalcomposition of the artificial diets couldhowever be improved in order to produce larvaeof optimal quality. Based on our researchfindings, the protein level and n-3 HUFA levelin the diet warrants further investigation inthis respect.     

应用高通量测序技术分析拟穴青蟹肠道及其养殖环境菌群结构

采用基于Illumina Hi Seq测序平台的高通量测序技术,对拟穴青蟹(Scylla paramamosain)肠道及其养殖池塘水体、底泥中细菌种类及丰度进行了研究。测序结果显示,3个样品共获得有效序列234575条,可聚类于2812个分类操作单元(OTUs),归属于拟穴青蟹肠道、养殖水体、池塘底泥样品的操作分类单元(OTU)个数分别为453、706和2547,其中有184个OTU均能在3个样品中检测到,在青蟹肠道和养殖水体、青蟹肠道和池塘底泥中分别检测到197和309个共有OTU。物种注释结果显示,拟穴青蟹肠道中优势细菌种类为变形菌门(Proteobacteria)(39.96%)、柔膜菌门(Tenericutes)(23.09%)和厚壁菌门(Firmicutes)(16.58%);养殖水体中优势细菌种类为变形菌门(63.02%)、放线菌门(Actinobacteria)(24.96%)和拟杆菌门(Bacteroidetes)(8.41%);池塘底泥中优势细菌种类为变形菌门(75.23%)、拟杆菌门(5.72%)和放线菌门(3.83%)。此外,对各样品中丰度最高的前10位OTU分析显示,不同样品中占优势地位的10种细菌在数据库(SILVA)缺乏相关已知序列,并且各样品中的优势细菌种类完全不同。实验结果表明拟穴青蟹肠道与其池塘养殖环境中菌群结构存在着密切的相关性,但肠道菌群同时具有一定的独立性,其优势细菌种类与养殖环境中优势细菌种类无关。本研究旨在为拟穴青蟹健康养殖和微生态调控提供实验依据。     

Effect of dietary cholesterol levels on growth performance,body composition and gene expression of juvenile mud crab Scylla paramamosain

A 56‐day feeding trial was conducted to investigate the effect of dietary cholesterol (CHOL) levels on growth performance, body composition and gene expression of juvenile mud crab (Scylla paramamosain). Four isonitrogenous and isoenergetic diets were formulated with 0.4%, 0.8%, 1.2% and 1.6% CHOL supplemented, and the final dietary CHOL concentrations were 0.72%, 1.11%, 1.49% and 1.83% respectively. Each dietary treatment was performed with three replicates (28 crabs per replicate, initial body weight 0.04 g). At the termination of the experiment, although the survival had no statistic difference in all treatments, the mud crabs fed the lowest CHOL diet had the lowest survival rate. The weight gain (WG) of mud crab significantly increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL level further increased. The total‐cholesterol (T‐CHOL) content in whole body had an increasing trend with the dietary CHOL level increased. Besides, dietary CHOL supplement generally increased the hepatic superoxide dismutase (SOD) activity, and the mud crabs fed diets CHOL1.11 and CHOL1.49 showed significantly higher value than those fed other diets. The hepatic aspartate aminotransferase (AST) activity decreased slightly with dietary CHOL level up to 1.11% and then significantly increased with CHOL level further increased. The mRNA expression of ecdysone receptor (EcR) gene in the eyestalk obviously increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL further increased. These results suggested that about 1.11% dietary CHOL seem fulfil to maintain good growth performance and healthy condition for juvenile S. paramamosain.     

Effect of fishmeal replacement with Artemia biomass as a protein source in practical diets for the giant freshwater prawn Macrobrachium rosenbergii

A 30-day feeding experiment was conducted in 160-L plastic tanks to evaluate the potential use of Artemia biomass as a protein source in practical diets for postlarval Macrobrachium rosenbergii (initial mean weight of 12.12–12.29 mg). Nine isoenergetic and isonitrogenous experimental diets (approximately 40% crude protein) were formulated by replacing levels of the fishmeal (FM) protein difference either with dried or frozen Artemia (0, 25, 50, 75 and 100%). The 0% Artemia treatment, in which Peruvian FM was the only main protein source, was considered to be the control diet. The results showed that prawn postlarvae (PLs) fed the FM control diet had a lower survival (46%) compared with all Artemia diets. Significant differences ( P <0.05) were, however, only found at 75% and 100% Artemia protein inclusion levels (survival of 68–77%). A gradual increase in growth performance (live weight gain, specific growth rate and total length) of the prawns was achieved on increasing dietary inclusion of Artemia protein. Additionally, the size distribution exhibited the same response as growth performance. However, prawns fed the frozen Artemia diets showed a better performance than the ones fed the dried Artemia diets. It can be suggested that Artemia biomass may totally replace FM in practical diets for PLs of the freshwater prawn M. rosenbergii .     

Effects of tank colour on larval survival and development of mud crab Scylla serrata (Forskål)

Hatchery culture of mud crabs has not yet achieved commercial viability despite decades of research efforts. Further research is therefore needed to better understand larval culture requirements of the crab. Based on anecdotal observations, an experiment was carried out to test whether the background colour of the culture vessel affected larval culture success. Newly hatched larvae of Scylla serrata were reared in culture vessels of five colours, i.e., black, dark green, maroon, sky blue and white. Larval survival and development were monitored daily until all of them either moulted to the first crab stage or died. The results showed clear effects of background colour on larval survival. A general tendency of higher larval survival in darker‐coloured backgrounds was evident. In particular, overall zoeal survival for larvae reared in black vessels was significantly higher than those reared in white ones. Background colour also appeared to affect larval development. Larvae reared in darker backgrounds generally had shorter development times and more synchronized moulting. A significant delay in zoeal development was observed in larvae reared in white vessels. Dark backgrounds possibly facilitated more efficient feeding, reduced settlement of larvae at the bottom of the vessels as well as minimized stress. This result appears to be the first to demonstrate that background colour can significantly affect larval survival and development of a crustacean species.     

Effects of temperature and salinity on the survival and development of mud crab, Scylla serrata (Forsskål), larvae

The combined effects of temperature and salinity on larval survival and development of the mud crab, Scylla serrata, were investigated in the laboratory. Newly hatched larvae were reared under 20 °C temperature and salinity combinations (i.e. combinations of four temperatures 25, 28, 31, 34 °C with five salinities 15, 20, 25, 30, 35 g L⁻¹). The results showed that temperature and salinity as well as the interaction of the two parameters significantly affected the survival of zoeal larvae. Salinity at 15 g L⁻¹ resulted in no larval survival to the first crab stage, suggesting that the lower salinity tolerance limit for mud crab larvae lies somewhere between salinity 15 and 20 g L⁻¹. However, within the salinity range of 20–35 g L⁻¹, no significant effects on survival of zoeal larvae were detected (P>0.05). The combined effects of temperature and salinity on larval survival were also evident as at low salinities, both high and low temperature led to mass mortality of newly hatched larvae (e.g. 34 °C/15 g L⁻¹, 34 °C/20 g L⁻¹ and 25 °C/15 g L⁻¹ combinations). In contrast, the low temperature and high salinity combination of 25 °C/35 g L⁻¹ resulted in one of the highest survival to the megalopal stage. It was also shown that at optimal 28 °C, larvae could withstand broader salinity conditions. Temperature, salinity and their interaction also significantly affected larval development. At 34 °C, the mean larval development time to megalopa under different salinity conditions ranged from 13.5 to 18.5 days. It increased to between 20.6 and 22.6 days at 25 °C. The effects of salinity on larval development were demonstrated by the fact that for all the temperatures tested, the fastest mean development to megalopa was always recorded at the salinity of 25 g L⁻¹. However, a different trend of salinity effects was shown for megalopae as their duration consistently increased with an increase in salinity from 20 to 35 g L⁻¹. In summary, S. serrata larvae tolerate a broad range of salinity and temperature conditions. Rearing temperature 25–30 °C and salinity 20–35 g L⁻¹ generally result in reasonable survival. However, from an aquaculture point of view, a higher temperature range of 28–30 °C and a salinity range of 20–30 g L⁻¹ are recommended as it shortens the culture cycle.     

复方磺胺嘧啶口灌给药在拟穴青蟹(Scylla paramamosain)体内药动学和组织分布与消除

研究了水温为(27±1)℃、盐度为10条件下,单剂量(100 mg/kg)口灌给药复方磺胺嘧啶(磺胺嘧啶SD:甲氧苄啶TMP=5:1)后,SD和TMP在拟穴青蟹(Scylla paramamosain)体内的药动学以及在肌肉、肝胰腺和鳃组织中的分布和消除规律.结果显示,拟穴青蟹口灌复方磺胺嘧啶后,血淋巴中SD和TMP药物浓度-时间关系曲线均符合一级吸收二室模型,SD和TMP的峰浓度(Cmax)分别为49.56 mg/L和2.79 mg/L,药时曲线下面积(AUC)分别为1417.6 mg/L.h和82.7 mg/L·h;肝胰腺是SD和TMP峰浓度最高的组织,其Cmax分别为59.36 mg/kg和74.82 mg/kg.由此可见,大量TMP蓄积在肝胰腺中,进入血液循环的TMP很少.在鳃组织中,SD和TMP的Cmax分别为51.89 mg/kg和42.58 mg/kg,消除半衰期分别为23.28 h和25.29 h;鳃组织中药物浓度比较高,且消除速度较快,推测其在药物代谢中承担着消除功能.在肌肉中,SD和TMP的Cmax分别为44.95 mg/kg和10.09 mg/kg,消除半衰期分别为25.09 h和35.08 h.以0.1 mg/kg和0.05 mg/kg分别为SD和TMP的最高残留限量(MRL),95％置信区间,推算SD和TMP在拟穴青蟹肌肉中的理论休药期分别为290.6 h和302.8 h,在肝胰腺中分别为340.4 h和377.0 h.     

不同糖源对拟穴青蟹仔蟹的生长、体成分及消化酶的影响

在水温26~30℃,盐度18~22条件下,初始体质量(0.012±0.000)g的拟穴青蟹仔蟹饲养在底铺1~2 cm细沙、边缘放5 cm^2瓦片的塑料水桶(直径20 cm,水深20 cm)中,投喂以葡萄糖、蔗糖、糊精、木薯淀粉、玉米淀粉、糊化木薯淀粉和糊化玉米淀粉为糖源的7种等氮等能饲料,养殖3周,研究不同糖源对拟穴青蟹仔蟹生长、体组成及消化酶活性的影响。试验结果显示,不同糖源显著影响拟穴青蟹仔蟹的生长性能(P<0.05);质量增加率和特定生长率依次为糊化木薯淀粉>糊化玉米淀粉>木薯淀粉>玉米淀粉>糊精>蔗糖>葡萄糖;葡萄糖试验组的成活率显著低于其他各组(P<0.05)。不同糖源对拟穴青蟹仔蟹体组成中粗蛋白和粗脂肪含量影响显著(P<0.05),对仔蟹的水分和灰分含量影响不显著(P>0.05);不同糖源对3种消化酶活性影响显著(P<0.05)。拟穴青蟹仔蟹对大分子糖源的生物利用度要大于小分子糖源。在本试验的研究条件下,7种常见糖源中糊化木薯淀粉是拟穴青蟹仔蟹的最适糖源。