龙头鱼中内源性甲醛产生的酶促机理初探

对比了龙头鱼不同内脏对肌肉甲醛含量的影响,其中肾脏活性最强;从龙头鱼肾脏中获得了提取物,在体外模拟体系中,该提取物能够将氧化三甲胺分解为甲醛和二甲胺,通过响应面分析,发现该提取物反应最适条件为50℃,pH=7,能够被三氯乙酸灭活而丧失分解氧化三甲胺的能力,该提取物在不同的温度和pH条件下呈现酶的特性,且分解产物甲醛和二甲胺的含量比例关系稳定,保持在1.6～1.8之间。在一定程度上解释了龙头鱼中甲醛的产生原因,表明龙头鱼中的甲醛可以自身产生。     

罗非鱼中红霉素残留量的高效液相色谱法的测定

建立了以高效液相色谱法测定罗非鱼中红霉素残留量的方法。提出了以乙腈为提取剂,经过液-液萃取、固相萃取、反萃取等步骤对样品进行分离净化的样品处理方法,该方法准确、灵敏度高。方法的检出限为400μg/kg。     

海水鱼饲养中的臭氧杀菌

近年来,臭氧灭菌已广泛应用于海水观赏鱼的养殖中,且效果良好。臭氧是氧的同素异形体。臭氧无色．具辛辣刺鼻的气味,有毒。臭氧在气态时极不稳定,会逐渐分解成氧。臭氧溶于水,会与水发生一连串的反应．它可杀灭水中的细菌及某些原生动物,但对杀灭鱼体的寄生虫却效果甚微。一、臭氧杀菌的机制臭氧在水中会发生分解,分解产物包括氢氧根（OH－）及氧分子等。而其中最重要的产物是氢氧离子,Baxendale曾报道;OH-的氧化能为-2SV（H－＝1M）,这个值比臭氧本身的氧化能都大,臭氧最高的氧化能在酸性溶液中为-2．07V．在碱性溶液中只有…     

几种抗菌素在鳖病防治中的合理应用

几种抗菌素在鳖病防治中的合理应用生产中，笔者根据青霉素、链毒素、红霉素等抗菌素药物的性能，采用注射、拌饵、泼洒、浸洗等不同方法来防治鳖病，效果显著。现介绍如下。青霉素，对革兰氏阳性细菌、阴性细菌均有作用，其抗菌效力不受溶液或其它组织分解产物影响，对寄...     

不同温度下2种沼虾磷酸酶活性变化的研究

用比色法测量4℃和-70℃下离体的罗氏沼虾和日本沼虾肝胰腺中的碱性磷酸酶、酸性磷酸酶酶活性在一周内的变化。试验结果表明,4℃条件下保存的日本沼虾与罗氏沼虾的离体组织中碱性磷酸酶和酸性磷酸酶酶活性有效测定下时间为3 d,-70℃下有效测定时间为2 d,对后续酶活性试验没有大的影响。     

水产养殖不可或缺的益生菌——类球红细菌

<正>中国科学院生态环境研究中心多年的研究证实,类球红细菌(Rhodobacter sphaeroides)WD-2株具有两个染色体,拥有广泛的能量代谢机制。在淡水、海水不同生物渗透压条件下正常代谢生长,在黑暗条件下好氧生长,光照条件下光合生长。可充分利用养殖水体的低级脂肪酸、杂蛋白、腐藻纤维的次级分解产物和三氮等有毒有害物质。主要代谢产物胞嘧啶、尿嘧啶、四吡咯、叶绿素、类胡萝卜素、SOD、5-氨基     

菲律宾蛤仔酶解产物的抑菌活性

以菲律宾蛤仔为原料,比较其胃蛋白酶、酸性蛋白酶、菠萝蛋白酶、胰蛋白酶和木瓜蛋白酶酶解产物的抑菌活性;利用正交实验优化抑菌活性最强的酶解产物的制备工艺,并测定最优酶解条件下酶解产物的相对分子质量分布。结果表明,菲律宾蛤仔胃蛋白酶酶解产物的抑菌活性最强,对金黄色葡萄球菌、大肠杆菌、枯草芽孢杆菌、酿酒酵母和副溶血弧菌均有一定的抑菌活性,其中对金黄色葡萄球菌、枯草芽孢杆菌的抑菌活性较高,对四联微球菌则未见明显的抑菌活性。胃蛋白酶的最优酶解工艺条件为：酶解时间2h,温度35℃,pH 2.0,加酶量3 000U/g,料水比1∶4;该条件下酶解产物的相对分子质量主要分布在5000以下。     

液化鱼蛋白和酸性稳定的鲜贮饲料的营养价值

用传统方法制作的鲜贮鱼饲料(pH4.0)含有多种活性酶体系,这些活性酶体系不仅把鱼蛋白质水解成短链的肽和游离的氨基酸,而且还使游离的氨基酸分解成氨和其他新陈代谢的产物。酸性稳定的鲜贮鱼饲料(pH2.0)仅含有由内源胃蛋白酶释放的多肽和微量的游离氨基酸及分解产物。液化鱼含有稳定的中等链长的多肽。液化鱼的制作过程是这样的:在温度为60℃和生理pH(6.2—6.6)下,让鱼体自溶分解不足一小时,然后经过巴氏法杀菌,再使之酸化到pH4.0。上述制作过程提供了一种适应于各种水生动物和陆生动物对营养不同需要量的调节自溶鱼蛋白中肽和游离氨基酸含量的办法。     

诺德的研究与开发

罗红霉素是第二代红霉素类药物,具有良好的药代动力学特征和广阔的临床应用前景。本文论述了水溶性复方罗红霉素散剂—诺德的开发研制过程,更为药物开发工作者提供了开发新产品的一个思路。     

“三氮”在水产养殖中的意义及其管理

<正> 水体中的氨氮、亚硝酸盐氮和硝酸盐氮,简称“三氮”。氮是含氮有机物质分解的产物,在水产养殖学上“三氮”的主要来源是鱼虾的粪便和残饵,它们在细菌的作用下经氧化—还原作用分解,在不同的条件下分解成不同形式的无机氮。“三氮”的含量及转化规律直接关系到养殖效果,在养殖用水的管理上有着重要的意义。     

Bioencapsulation of five forms of erythromycin by adult Artemia salina (L.)

Uptake of five chemical forms of erythromycin by adult Artemia salina (L.) (erythromycin phosphate – EP, erythromycin stearate – ES, erythromycin estolate – EE, erythromycin hydrate – EH and crystalline erythromycin – CE) was investigated in two trials. In each trial, final erythromycin concentration in Artemia tissue and survival after a 12‐h bioencapsulation period were determined. In the first trial, Artemia tissue concentration after a 12‐h bioencapsulation period was significantly (P < 0.05) affected by erythromycin form with ES (68.5 ± 3.3 μg mL^?1, mean ± SEM) ≈ EH (61.2 ± 3.4 μg mL^?1) > CE (37.1 ± 10.7 μg mL^?1) > EP (16.4 ± 7.7 μg mL^?1) > control. In trial 2, Artemia tissue concentration was also significantly (P < 0.05) affected by erythromycin form with EE (111.4 ± 9.6 μg mL^?1) > CE (89.1 ± 1.7 μg mL^?1) > ES (78.9 ± 1.6 μg mL^?1) > EP (33.4 ± 5.2 μg mL^?1) > control. Survival was significantly affected by erythromycin form in trial 1 with EP=control (100 ± 0.0%) > ES (74.4 ± 2.0%) > CE (32.2 ± 0.3%) > EH (8.8 ± 4.4%). In trial 2, survival was also significantly affected by erythromycin form with EP=control (100 ± 0.0%) > ES (67.1 ±3.7%) > CE (52.5 ± 7.7%) > EE (5.0 ± 2.5%). Based on both uptake and survival, EP and ES appear to be appropriate compounds for bioencapsulation of erythromycin using live adult Artemia.     

Bioencapsulation of erythromycin using adult brine shrimp, Artemia franciscana (Latreille)

Live adult brine shrimp, Artemia franciscana (Latreille), were enriched with erythromycin to determine if Artemia could accumulate therapeutic levels for subsequent feeding to young fish. Three trials were conducted to determine the erythromycin incorporation and survival rates of enriched Artemia when fed either liposomes containing erythromycin or various erythromycin suspensions. Erythromycin concentration in Artemia fed a liposome suspension was low (∼ 5 μg mL⁻¹) relative to Artemia fed the direct suspension (> 100 μg mL⁻¹) over the same time period. When enriched with suspensions up to 1 g erythromycin L⁻¹ sea water for 14 h, Artemia survival was not significantly affected ( P > 0.05) relative to controls. Using a suspension of 1 g L⁻¹, tissue erythromycin concentrations of 109 ± 16 μg erythromycin mL⁻¹  Artemia homogenate (mean ± SEM) were achieved after 12 h. Concentrations above 170 μg mL⁻¹ were obtained using suspensions of 2–5 g L⁻¹, but Artemia survival significantly ( P < 0.05) decreased.     

Uptake of erythromycin by first-feeding sockeye salmon,Oncorhynchus nerka (Walbaum), fed live or freeze-dried enriched adult Artemia or medicated pellets

The potential to use adult Artemia to deliver erythromycin to first-feeding sockeye salmon, Oncorhynchus nerka (Walbaum), was investigated in three trials. In the first trial, first-feeding sockeye were fed live erythromycin enriched adult Artemia or pellets containing equal amounts of erythromycin for 35 days. At the end of the trial, tissue erythromycin concentration of the fish fed the live Artemia was significantly greater (P < 0.05, 25.52 +/- 1.29 microg mL(-1); mean +/- SEM), than the tissue concentration of the fish fed the pellets (0.72 +/- 0.01 microg mL(-1)). In the second trial, first-feeding sockeye were fed either live or freeze-dried bioencapsulated erythromycin (adult Artemia) or pellets containing erythromycin daily for 21 days. Mean daily erythromycin concentration in fish fed the freeze-dried Artemia, live Artemia, or pellets did not differ significantly. In the third trial, apparent erythromycin digestibility was determined. Significantly more (P < 0.05) erythromycin was retained by juvenile sockeye fed freeze-dried bioencapsulated erythromycin (98.3 +/- 1.0%) compared with medicated pellets (89.2 +/- 1.7%). Uptake of bioencapsulated erythromycin from adult Artemia (live or freeze-dried) appears to be greater than uptake from pellets. Freeze-dried and live Artemia were equally effective at delivery suggesting enriched freeze-dried adult Artemia could be produced into a highly palatable, consistent, off-the-shelf product.     

Effects of chloramphenicol, erythromycin, and furazolidone on growth of Isochrysis galbana and Chaetoceros gracilis

This study focused on determining the effects of antibiotics on microalgae used as food for scallop larvae. Six different dose levels of chloramphenicol, erythromycin, and furazolidone were added to cultures of Isochrysis galbana and Chaetoceros gracilis. An in vivo experiment was subsequently conducted to determine the effect of chloramphenicol and erythromycin on larval survival of the Pacific calico scallop Argopecten ventricosus in tanks and on the population of its associated bacteria. Results showed that growth of I. galbana was not significantly affected by chloramphenicol or erythromycin at the test doses of 0.5, 1.0, 3.0, 6.0, 9.0, and 12.0 mg/l. C. gracilis was significantly sensitive to erythromycin and chloramphenicol at doses higher than 0.5 and 3.0 mg/l, respectively. Furazolidone inhibited the growth of both I. galbana and C. gracilis at all test doses. Results showed that exposure of scallop larvae to a dose of 6 mg/l chloramphenicol or erythromycin did not significantly affect growth of I. galbana, significantly enhanced survival of the scallop larvae, and inhibited the growth of Vibrio spp. in tanks. This study demonstrated the adverse effect of chloramphenicol, erythromycin and furazolidone on I. galbana and C. gracilis microalgae but the positive effect on survival of the scallop larvae, decreasing associated bacterial population.     

A histological assessment of damage in rainbow trout, Salmo gairdneri Richardson, fed rations containing erythromycin

Abstract. Rainbow trout fed prepared rations containing therapeutic levels of erythromycin (110 mg/kg daily) developed lesions in epithelial cells of the first proximal segment of the nephron. Pathological changes which developed within 24 h were characteristic of congestive overloading of lysosomes. Treated fish became anorexic within 2–3 weeks. Affected epithelial cells offish after 14 days of anorexia contained residual bodies in an otherwise normal appearing cytoplasm. Cell injury was reversible. Since the onset of anorexia corresponded with the completion of the recommended treatment period and damaged cells repair rapidly, erythromycin should nevertheless be retained as the treatment of choice for bacterial kidney disease.     

Acute LD50 and kidney histopathology following injection of erythromycin (Erythro-200) and its carrier in spring chinook salmon, Oncorhynchus tshawytscha (Walbaum)

We evaluated the toxicity of commercial injectable erythromycin (Erythro-200) and the injectable drug carrier alone (PEG-400, ethyl alcohol and ethyl acetate) in sub-adult spring chinook salmon, Oncorhynchus tshawytscha (Walbaum). Both compounds were toxic to salmon when administered in high dosages. The 50% lethal dose (LD₅₀) of the erythromycin within its carrier (Erythro-200) at 12 °C was estimated at 429 mg erythromycin kg^–1 or 2.145 mL kg^–1 when measured by volume. The LD₅₀ of the drug carrier alone was 2.95 mL kg^–1 by volume or equivalent to 3.21 g kg^–1 of the carrier. We evaluated and scored the histopathology in kidney sections removed from fish 96 h after injection with Erythro-200, the drug carrier alone, or sterile phosphate buffered saline (PBS) that served as a reference control. Kidneys from fish injected with saline had lowest average pathology scores; those injected with the carrier had moderate scores; and the pathology score was highest in tissues from erythromycin-injected fish. In tests at 12 °C, vacuoles were more prominent in proximal and distal tubules of fish injected with higher dosages of 403 and 545 mg erythromycin kg^–1 than in tissues from fish injected with 299 mg kg^–1.     

Action of selected antibiotics on four common bacteria associated with diseases of fish

Abstract. Four bacteria commonly associated with diseases of fish ( Aeromonas hydrophila complex, Aeromonas salmonicida, Flexibacter columnaris -like organisms and Pseudomonas fluorescens ) were evaluated in a serial dilution system for susceptibility to four antibiotics commonly used in the treatment of bacterial fish diseases (chloramphenicol, erythromycin, furpyrinol and oxytetracycline). Findings were expressed as minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Furpyrinol was found to have the lowest MIC and MBC against A. hydrophila complex, A. salmonicida and F. columnaris-like organisms. MIC and MBC's for oxytetracycline were complicated by the presenceof R-plasmids, but were less than 4.0 mcg/ml for those without plasmids. Pseudomonas fluorescens was susceptible only to oxytetracycline. MIC for all groups of organisms using chloramphenicol was generally less than 16.0 mcg/ml. Susceptibility to erythromycin by these groups of organisms was greater than 16 mcg/ml.     

Bioassay Procedure for the Evaluation of Erythromycin Activity in Aquaculture Environments

A new bioassay procedure was developed for the detection of erythromycin in aquaculture samples using a strain of a Stenotrophomonas as an indicator organism. Conventional disk-plate and well-plate radial diffusion assay procedures were developed, as well as a third procedure using the same indicator organism in Luria-Bertani (LB) broth, supplemented with the indicator dye Brilliant Black (40 μg/mL) in a multi-well microtiter plate. For both the disk-plate and well-plate radial diffusion assays, the response reflected in the size (width) of the growth inhibition zone, which was linear over the tested concentration range of 0.05 to 2.0 μg erythromycidml. The limit of quantitation of the bioassay was at 0.05 μg erythro-mycidml. Among the three methods of assay tested with Stenotrophomonas sp., the semi-quantitative dye reduction method is easy to read and is not diffusion dependent. This method allows for processing of more samples and more replication on a single titer plate. This new indicator organism is specific for erythromycin when tested in the presence of other antibacterial agents, i.e., oxytetracycline (Terramycin®) and/or Romet-Ma. This new bioassay procedure is suitable for quantitation of low concentrations of erythromycin in aquaculture water and sediment samples.