气相色谱法测定鱼虾肌肉组织中氯霉素的残留量

鱼虾肌肉组织中氯霉素残留量的检测有很多种方法 ,定量确认方法一般有气相色谱法 (GC) ,高效液相色谱法 (HPLC) ,气相色谱一质谱联机 (GC -MC) ,液相色谱—质谱联机 (LC -MC)等方法 ,本文采用GC法 (ECD)研究测定了鱼虾肌肉中氯霉素的残留量。用乙酸乙脂提取样品中的氯霉素 ,经去蛋白质 ,脱脂 ,过C18柱后 ,用BSYFA -TMCS衍生后进样。方法的回收率为 6 4 5± 8 7% ,检测限为 0 1～ 1μg/kg。     

水产品中氯霉素、甲砜霉素、氟苯尼考、氟苯尼考胺多残留的同时测定—GC/MS法

采用气相色谱-质谱法建立基质加标标准曲线,对中国对虾、大菱鲆、鲫鱼、鳗鱼、蟹、甲鱼6种主要养殖水产品肌肉组织中氯霉素类药物:氯霉素(CAP)、甲砜霉素(TAP)、氟苯尼考(FF)及其代谢物氟苯尼考胺(FFA)的多残留同时进行检测。结果显示,CAP在2–200 ng/ml浓度范围内,线性关系良好;TAP、FF和FFA在5–200 ng/ml浓度范围内,线性关系良好,其相关系数均大于0.990。加标回收率在76.4%–94.3%之间,相对标准偏差在5.7%–13.9%之间。检出限:CAP为0.2μg/kg,TAP、FF和FFA均为1.0μg/kg。定量限:CAP为0.5μg/kg,TAP、FF和FFA均为3.0μg/kg。研究表明,该方法具有准确、高效、灵敏、特异性强的特点,可以满足水产品中CAP、TAP、FF和FFA多残留的同时检测的要求。     

QuEChERS-UPLC-MS/MS法测定水产品中孔雀石绿和酰胺醇类抗生素残留量

建立了超高效液相色谱质谱联用法同时测定水产品肌肉组织中孔雀石绿和酰胺醇类抗生素残留的方法。样品经QuEChERS方法提取净化后,采用液相色谱-串联质谱测定,内标法定量。孔雀石绿(malachite green,MG)、隐色孔雀石绿(leucomalachite green,LMG)、氯霉素(chloramphenicol,CAP)和氟甲砜霉素(florfenicol,FF)在0.5～50.0 ng/mL质量浓度范围内线性良好(r≥0.999 4)。甲砜霉素(thiamphenicol,TAP)在2.0～100.0 ng/mL质量浓度范围内线性良好(r≥0.999 6)。MG、LMG、CAP和FF的检出限为0.1μg/kg,定量限为0.5μg/kg;TAP的检出限为0.4μg/kg,定量限为2.0μg/kg。MG、LMG、CAP和FF在0.5、2.0和10.0μg/kg加标水平时,加标回收率为72.0%～102.6%,精密度小于6.4%;TAP在2.0、10.0和50.0μg/kg加标水平时,其加标回收率为76.5%～95.4%,精密度小于5.1%。本方法适用于检测水产品中孔雀石绿类和酰胺醇类抗生素的残留,可为提升水产品质量安全水平提供技术支持。[中国渔业质量与标准,2020,10(1):60-67]     

DcELISA检测泥鳅、鲫鱼中氯霉素残留方法的应用

应用直接竞争酶联免疫吸附试验方法(dcELISA)快速定量测定泥鳅、鲫鱼肌肉中氯霉素(CAP)残留量.氯霉素浓度在0.05～10ng/g范围内具有良好的线性关系,线性方程为y=-0.33-1.88x,r2=0.995,向样品中分别添加0.1、0.3、0.9ng/g三个浓度水平的氯霉素标准品,泥鳅样品的平均回收率分别为87.2%、88.9%、93.0%,鲫鱼样品的平均回收率分别为86.1%、79.9%、99.0%.最低检测限为0.05ng/g,批内变异系数为8.0%.批间变异系数为7.2%,结果表明该方法灵敏度高,重复性好,适合在泥鳅、鲫鱼肉样中氯霉素残留筛选检测.     

GC/MS法同时测定水产品中氯霉素、氟甲砜霉素及甲砜霉素残留量

建立了气相色谱-负离子化学电离源质谱同时测定水产品中氯霉素(CAP)、氟甲砜霉素(FF)和甲砜霉素(TAP)残留量的方法。通过优化色谱条件,实现了氯霉素、甲砜霉素及氟甲砜霉素三甲基硅(TMS)衍生物的良好分离,检测模式采用选择离子检测(SIM),监测离子为:氯霉素(m/z376、378、466、468),氟甲砜霉素(m/z339、341、429、431)及甲砜霉素(m/z409、411、499、501),分别选择466、339、409作为定量离子。方法建立的基质添加标准曲线,有效地消除了基体效应的影响,其衍生物的峰面积与其浓度在CAP为2.0～200.0ng/ml,FF和TAP在5.0～200.0ng/ml时呈良好线形关系,线性相关系数均大于0.998。基质加标实验表明,方法的准确度和精密度满足水产品中药残检测的要求。CAP的测定低限为0.3μg/kg,FF和TAP的测定低限为1.0μg/kg。     

QuECHRS结合UPLC-MS/MS法测定水产品中酰胺醇类抗生素残留及基质效应

为获得一种快速测定水产品中酰胺醇类抗生素残留的方法,本研究建立了QuECHERS结合超高效液相色谱串联质谱(UPLC-MS/MS)测定氯霉素(CAP)、氟苯尼考(FF)和甲砜霉素(TAP)残留的方法,并对其基质效应进行了评价。结果表明,该方法下CAP、FF在0. 1～100. 0 ng/mL以及TAP在0. 5～100. 0 ng/mL质量浓度范围内线性关系良好,相关系数大于0. 999 8。CAP和FF检测限(LOD)和定量限(LOQ)分别为0. 10和0. 50μg/kg; TAP检测限(LOD)为0. 50μg/kg,定量限(LOQ) 1. 00μg/kg。3种酰胺醇类抗生素在1. 0、5. 0和10. 0μg/kg 3个添加水平下的平均回收率在(84. 5±4. 64)%～(106. 1±8. 69)%之间,日内精密度为3. 17%～9. 74%,日间精密度为2. 26%～7. 90%。同时在该检测方法下,评价了待测物浓度和基质浓度对基质效应的影响。结果发现,除CAP在1. 00～100. 00 ng/mL质量浓度范围内的基质效应可以忽略以外,随目标物浓度的降低,其基质效应值逐渐减小;随着样品基质浓度的增加,基质效应从基质增强变为基质抑制。因此,在检测水产品中酰胺醇类抗生素残留时均要考虑基质效应对检测结果的影响,建议采用基质标准曲线进行定量校准,以确保检测结果的准确性。该方法快速、准确、重复性好、环境友好且操作简单,可用于水产品中酰胺醇类抗生素残留量的测定。     

高效液相色谱-串联质谱法测定池塘沉积物中氯霉素残留

[目的]建立一种使用液相色谱-串联质谱联用仪快速准确检测池塘沉积物中痕量氯霉素残留的方法,为水产品中氯霉素污染来源的排查提供技术支持。[方法]底泥经润湿后,经乙酸乙酯水饱和溶液提取,Sep-Pa K C_(18)固相萃取柱净化,Shim-Pack XR-ODS色谱柱分离,采用甲醇和水为流动相,并用梯度洗脱对待测物进行分离,以氘代氯霉素(氯霉素-D5)为内标,采用负离子扫描,多反应监测模式(MRM),定性离子对m/z为321→152.0,256.8,定量离子对m/z为321→152.0。[结果]氯霉素类药物在0.5~10.0 ng/m L范围内线性良好,相关系数均大于0.99,本方法的检出限为0.1μg/kg,定量限为0.3μg/kg。3个加标水平(0.5、1.0和5.0μg/kg)的平均回收率为90.1%~96.6%,相对标准偏差为2.4%~7.0%。[结论]实验结果符合氯霉素药物残留检测的相关法规要求,适用于淡水池塘沉积物中氯霉素残留的定性定量检测。     

畜禽产品中喹乙醇代谢物残留测定方法优化

目的建立动物源性食品(猪肉、猪肝、禽肉)中喹乙醇代谢物3-甲基喹噁啉-2-羧酸(MQCA)高效液相色谱-串联质谱法。方法样品通过偏磷酸水解提取MQCA,MAX固相萃取柱净化。采用0.1%甲酸溶液和甲醇溶液作为流动相进行梯度洗脱,质谱(ESI+)采用多离子检测模式(MRM)对MQCA的定量离子和定性离子进行监测。结果该方法10 min完成目标化合物的分析,MQCA在0.5～2μg/kg浓度范围内呈良好的线性关系,MQCA在0.5μg/kg、1μg/kg和2μg/kg添加水平的回收率为75.4%～105%,相对标准偏差小于7.96%(n=6),方法检出低限为0.1μg/kg。结论该方法前处理耗时短、灵敏度高、回收率高,适用于动物源性食品(猪肉、猪肝、禽肉)中喹乙醇代谢物3-甲基喹噁啉-2-羧酸(MQCA)的残留测定。     

UPLC-MS/MS法测定水产品中7种喹诺酮类兽药残留

采用超高效液相色谱-串联质谱(UPLC-MS/MS)法，检测水产品中7种喹诺酮药物残留。选取青鱼、泥鳅和南美白对虾样品，用1%甲酸-乙腈超声提取后，经Oasis? Prime HLB固相萃取柱一步净化，氮吹浓缩，最后用10%甲醇复溶，0.1%甲酸水和纯甲醇作为流动相进行梯度洗脱，流量为0.3 mL/min，在电喷雾-多反应监测正离子模式下，7种喹诺酮(QNs)均采用内标法定量。结果表明，7种QNs药物在1.0～100.0μg/kg范围内，呈良好的线性关系，相关系数(R²)均高于0.998 000。7种QNs在空白样品中添加浓度分别为5.0,1.0和20.0μg/kg时，在青鱼中回收率为92.71%～105.31%，泥鳅中回收率为92.31%～109.38%，南美白对虾中回收率为92.31%～106.76%。该方法具有较好的准确度和重复性。按照特征离子色谱峰信噪比(S/N)=3计算得出，7种QNs检出限为0.01～0.34μg/kg，定量限为0.04～0.87μg/kg。指出，该方法操作简便，灵敏度高，准确度好，适合大批量水产品中7种喹诺酮药物残留的检测分析。     

气相色谱法测定鸡蛋中氯霉素残留量

研究了鸡蛋中氯霉素残留的气相色谱测定方法。样品经乙酸乙酯提取后,用SylonBFT衍生化,进电子捕获检测仪(ECD)测定,外标法定量。结果表明,方法的线性范围在1.0～300ng/mL之间,平均回收率达93.4%,平均相对标准偏差5.5%,检测限为0.1μg/kg。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.