Au@PVP核壳纳米粒子作为表面增强拉曼散射基底检测孔雀石绿

采用水热法合成了粒径均一、壳层厚度可控的Au@PVP核壳纳米粒子,利用壳层PVP分子分散纳米粒子的特性,使其形成均一、排列致密的单层结构,利用其内核金纳米粒子的等离子共振效应实现了孔雀石绿( MG)分子的表面增强拉曼检测。通过优化吸附时间与壳层厚度,在致密的、均匀的核壳纳米粒子表面增强拉曼散射(SERS)基底上实现MG分子高灵敏分析检测,检测线性范围1×10-10~1×10-5 mol/L,线性相关系数R2达到0.98,检出限可达1×10-12 mol/L。将本方法用于罗非鱼鱼肉中MG含量检测,样品未检出,样品加标回收率为70.8％~126.0％。结果表明,本方法快速准确、操作简单,可用于鱼肉中MG的快速检测。     

Simultaneous screening and confirmation of multiple classes of drug residues in fish by liquid chromatography-ion trap mass spectrometry

LC-ion trap mass spectrometry was used to screen and confirm 38 compounds from a variety of drug classes in four species of fish: trout, salmon, catfish, and tilapia. Samples were extracted with acetonitrile and hexane. The acetonitrile phase was evaporated, redissolved in water and acetonitrile, and analyzed by gradient chromatography on a phenyl column. MS² or MS³ spectra were monitored for each compound. Qualitative method performance was evaluated by the analysis over several days of replicate samples of control fish, fish fortified with a drug mixture at 1 ppm, 0.1 ppm and 0.01 ppm, and fish dosed with a representative from each drug class. Half of the 38 drugs were confirmed at 0.01 ppm, the lowest fortification level. This included all of the quinolones and fluoroquinolones, the macrolides, malachite green, and most of the imidazoles. Florfenicol amine, metronidazole, sulfonamides, tetracyclines, and most of the betalactams were confirmed at 0.1 ppm. Ivermectin and penicillin G were only detectable in the 1 ppm fortified samples. With the exception of amoxicillin, emamectin, metronidazole, and tylosin, residue presence was confirmed in all the dosed fish.     

莫桑鼻给非鲫滤泡闭锁中卵黄溶致液晶形成的自源过程

作者前面的工作和本文的研究结果表明,莫桑鼻给非鲫滤泡闭锁中卵黄溶致液晶的形成有两个过程,即自源过程和异源过程,自源过程发生在卵母细胞内,是卵黄球非结晶区自发消化的过程,异源过程是颗粒细胞吞噬卵黄球,胞内消化卵黄球的过程。虽然,自源过程是一个初始的不完全过程,但它在整个卵黄溶致液晶的形成中起“开启”作用。本文讨论了卵黄溶致液晶形成的相变问题,同时提出了“生物学相变”和“酶致相变”的概念。     

Quantitation and identity confirmation of residues of quinolones in tilapia fillets by LC-ESI-MS-MS QToF

A method for simultaneous determination of flumequine (FLM), oxolinic acid (OXO), sarafloxacin (SAR), danofloxacin (DAN), enrofloxacin (ENR), and ciprofloxacin (CIP) in tilapia (Orechromis niloticus) fillets, using liquid chromatography-tandem mass spectrometry (LC-ESI-MS-MS QToF) is presented. The quinolones were extracted from the food matrix with a solution of 10% trichloroacetic acid-methanol (80:20 v/v) with ultrasonic assistance. Clean-up of the extract solution was performed by using polymeric solid-phase extraction cartridges. The LC separation was carried out on an octadecyl hybrid silica column (C₁₈, 150 mm × 3 mm, 5 μm). The column temperature was set at 30 °C, and gradient elution (0.2 mL min⁻¹) was performed using water and acetonitrile, both containing 0.1% of acetic acid, as mobile phase components. The analytes were ionized using electrospray in the positive polarity mode. The following analytical results were obtained: linearity was about 0.99 for all the quinolones; intra and inter-assay precision (RSD%) were lower than 12.7 and 20%, respectively; and recoveries were from 89 to 112%. The quantitation limits were below the maximum residue limits established for the analytes. The method is suitable for the determination of quinolone residues in fish fillets and the QToF technique made it possible to obtain m/z ratios with less than 10 ppm of error for each analyte.     

莫桑鼻给非鲫卵子发生的扫描电镜观察

用冰冻断裂术制样,通过扫描电镜首次观察了莫桑鼻给非鲫的卵子发生过程。结果表明卵母细胞内卵黄积累迅速,卵黄球最先在细胞核周围出现,然后逐渐充满细胞内,卵膜由卵母细胞产生。     

Protein Enrichment of Apple Pomace and Use in Feed for Nile Tilapia

The purpose of this paper is to investigate the protein enrichment of apple pomace by Gongronella butleri through solid-state cultivation and addition of this material as feed for tilapia fry (Oreochromis niloticus). Factorial experimental design was used for the assessment of culture conditions to determine the effects of the source of nitrogen, initial moisture, and granulometry on the protein enrichment of apple pomace. During culture, the consumption of reducing sugars and the production of soluble protein were determined. The best conditions obtained were with urea (5% w/w), initial moisture of 70% and granulometry in the range from 0.85 to 1.70 mm, producing 19.63% of soluble protein. The fry submitted to the diet containing treated apple pomace presented an increase of 44% in body mass, demonstrating that apple pomace biotransformed may represent an excellent food supplement.     

A ratio‐dependent eco‐epidemiological model of the Salton Sea

Ratio‐dependent models set up a challenging issue for their rich dynamics incomparison to prey‐dependent models. Little attention has been paid so far to describe the importance of transmissible disease in ecological situation by considering ratio‐dependent models. In this paper, by assuming the predator response function as ratio‐dependent, we consider a model of a system of three non‐linear differential equations describing the time evolution of susceptible and infected Tilapia fish population and their predator, the Pelican. Existence and stability analysis of different equilibria of the system lead to different realistic thresholds in terms of system parameters. The condition for extinction of the species is also worked out. Our analytical and numerical studies may be helpful to chalk out suitable control strategies for minimizing the extinction of the Pelicans. We also suggest that supply of alternative food source for predator population may be used as a possible solution to save the predator from their extinction. Copyright © 2005 John Wiley & Sons, Ltd.     

罗非鱼除藻对月湖水质的影响

宁波月湖放养罗非鱼前后的水体理化因子检测结果表明, 放养罗非鱼后水体透明度有较大改善,年平均升高0. 16m,与同期进行的浮游生物调查结果十分吻合.与此相反,水体COD、TP和TN比前一年均有不同程度的增加,其中TN差异显著(P<0.05),TP为极显著(P<0.01);通过与进水口的水质对比,发现TN、TP受外源水质影响明显.多元回归方法分析证明月湖TP的增加与罗非鱼放养之间存在一定的线性关系,而罗非鱼对浮游藻类的牧食压力导致了水体叶绿素的减少及透明度的提高.     

尼罗罗非鱼血液研究

本文报导了66尾池养尼罗罗非鱼(Tilapia nilotica)血液中的红细胞数、白细胞数、血红蛋白值、红细胞脆性值、比积及血液比重值、血细胞沉降率、白细胞分类计数和血细胞大小等正常值以及上述常数值雌雄个体差异和繁殖季节前后差异等变化规律,为尼罗罗非鱼血液常数值提供了较为系     

阳离子交换树脂脱除罗非鱼酶解液腥味的研究

通过静态吸附实验研究了5种阳离子交换树脂对罗非鱼肉酶解液腥味的脱除效果,发现阳离子树脂均有适当的脱腥作用,其中D113型树脂效果最好。在单因素实验的基础上进行正交实验设计,优化D113型树脂脱腥工艺,结果表明,在25℃下脱腥的最佳工艺参数为酶解液pH值5.0、树脂用量5.0%(m/v)、接触时间1.0h。在此工艺条件下,酶解液的腥味最低,蛋白质回收率为80.61%。本工艺可用于鱼蛋白酶解液的脱腥。