Effects of ascorbic acid enrichment by immersion of rainbow trout (Oncorhynchus mykiss, Walbaum 1792) eggs and embryos     

Bahram Falahatkar  Konrad Dabrowski  Murat Arslan  & Jacques Rinchard 《Aquaculture Research》2006,37(8):834-841

This study was conducted to examine the effects of different forms and concentrations of ascorbic acid (vitamin C), and different enrichment times (24 and 48 h post ovulation) on egg, embryo and alevin ascorbate concentrations and survival of rainbow trout (enrichment was at the ova stage). In experiments 1 and 2, fertilized eggs were immersed in water containing ascorbate at 0 (control), 100, 1000 mg L^?1 l ‐ascorbic acid (AA) and 2000 mg L^?1 l ‐ascorbyl monophosphate (AP). In experiment 3, 0 (control), 500 and 1000 mg L^?1 AA neutralized (N) with NaOH, 1000 mg L^?1 AA non‐neutralized (NN), 1000 and 2000 mg L^?1 AP immersions were used. The mean total ascorbic acid (TAA) and dehydroascorbic acid (DHA) concentrations were measured before fertilization, at 3 and 24 h after fertilization, at the eyed stage, and in hatched alevins. We observed significant differences in TAA concentration at different immersion levels at 3 and 24 h after fertilization. Survival decreased significantly depending on the level of vitamin C, pH of the solutions and immersion time. We suggest that when broodstock rainbow trout do not have enough vitamin C in their ovaries, immersion of eggs in 1000 mg L^?1 of neutralized AA may be useful.  相似文献   

Morphological characterization and notes on the life cycle of a newly discovered variant of Loma salmonae (Putz, Hoffman & Dunbar) from a natural infection of chinook salmon, Oncorhynchus tshawytscha (Walbaum)     

Lovy J  Wadowska DW  Wright GM  Speare DJ 《Journal of fish diseases》2004,27(10):609-616

Two variants of Loma salmonae occur in net-pen reared chinook salmon, Oncorhynchus tshawytscha. The typical variant (OA) has a host specificity for salmonids of the genus Oncorhynchus whereas the atypical variant (SV) has a host specificity for brook trout, Salvelinus fontinalis, and in this study, the ultrastructure of the two are compared. In fish at 8 weeks post-exposure xenomas of the SV variant have a very high proportion of mature spores compared with other developmental stages, while in xenomas of the OA variant there are fewer spores and many other developmental stages. Spores of the SV variant had up to 20 turns of their polar tube whereas those of the OA variant only had 17. Furthermore, the spores of the SV variant were significantly larger than those of the OA variant. The sporophorous vesicle for both variants appears to form around a sporogonial plasmodia, which results in many spores developing within the vesicle.  相似文献   

Quantification of Flavobacterium psychrophilum in rainbow trout, Oncorhynchus mykiss (Walbaum), tissues by qPCR     

Orieux N  Bourdineaud JP  Douet DG  Daniel P  Le Hénaff M 《Journal of fish diseases》2011,34(11):811-821

A qPCR assay was developed for rapid and sensitive detection of Flavobacterium psychrophilum, the aetiological agent of bacterial cold-water disease and rainbow trout fry syndrome in salmonid fish worldwide. A set of F. psychrophilum-specific primers based on 16S rRNA gene sequences was designed and validated for specific detection and quantification of DNA isolated from representative strains of F. psychrophilum. The qPCR assay exhibited a high specificity for the 16S rRNA gene of F. psychrophilum (from 4 × 10(8) down to 11 copies per reaction) but not for other Flavobacterium species or other bacteria including fish pathogens. This qPCR-based method proved to be useful in the quantification of the F. psychrophilum titre present within organs dissected out from diseased fish. As the F. psychrophilum genome contains six copies of the 16S rRNA gene, we could infer a limit of detection corresponding to two bacteria per reaction, corresponding to 800 bacteria per fish tissue sample, and therefore 20 F. psychrophilum cells mg(-1) of tissue (for sample weighing 40 mg). The qPCR assay reported here could be a useful tool for veterinary diagnostic laboratories to monitor the F. psychrophilum infection level in fish farms.  相似文献   

In vivo treatment with cycloheximide or actinomycin D inhibits early embryonic development in rainbow trout (Oncorhynchus mykiss)     

J.J. Nagler 《Fish physiology and biochemistry》2000,22(1):61-66

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A rapid immunoperoxidase-based virus neutralization assay for salmonid alphavirus used for a serological survey in Northern Ireland   总被引：1，自引：0，他引：1  

Graham DA  Jewhurst VA  Rowley HM  McLoughlin MF  Todd D 《Journal of fish diseases》2003,26(7):407-413

A modified virus neutralization (VN) assay was developed to replace an existing assay read on the presence or absence of virus-induced cytopathic effect (CPE). The modified assay used a monoclonal antibody to salmon pancreas disease virus as the first layer of an immunoperoxidase (IPX)-based immunostaining technique to detect viral growth. The IPX-based VN assay required only 3 days to perform, and the adoption of a 96-well microtitre format facilitated a high throughput of samples requiring small volumes of serum, cells and virus. When 352 sera from farmed salmon and 302 sera from farmed trout were tested by both the modified and the original CPE-based assays, overall correlations of 97.72 and 96.03% were, respectively, obtained (96.94% combined). When the modified assay was used to test 188 sera collected from wild salmonids in freshwater river systems in Northern Ireland, no positive results were recorded.  相似文献   

Control of ion transport by the sperm duct epithelium of brook trout (Salvelinus fontinalis)     

William S. Marshall  Sharon E. Bryson  David R. Idler 《Fish physiology and biochemistry》1989,7(1-6):331-336

The sperm duct epithelium of brook trout (Salvelinus fontinalis), mountedin vitro in Ussing-style epithelial chambers actively absorbs Na⁺ (measured as the short-circuit current, I_sc) and secretes K⁺ (measured using⁸⁶Rb⁺ as tracer). Dibutyryl-cyclic-adenosine monophosphate (db-cAMP) and 3-isobutyl-1-methylxanthine (IMX) produce a rapid, sustained stimulation of both ion transport processes, but the hormone connected to the response is unknown. Purified sockeye salmon CON A2 gonadotropin (GtH) produces a dose-dependent, rapid and sustained rise in Na⁺ uptake and K⁺ secretion. The time course, electrophysiological and transport characteristics are similar to those evoked by IMX. Carbohydrate-poor (chum salmon CON A1) GtH is ineffective. Pretreatment of fish with 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-P) significantly increases milt volume but is without effect on resting or stimulated (IMX + db-cAMP) levels of sperm duct ion transport. This is the first indication of a direct, rapid action of GtH on ion transport by the vertebrate blood-testis barrier. The results suggest direct involvement of GtH in control of later stages of sperm maturation.  相似文献   

甘肃加工型番茄叶果真菌病原鉴定及主要病害   总被引：1，自引：0，他引：1  

雷玉明  ;刘晓刚 《中国园艺文摘》2014,(7):39-41

经田间采集、分离培养、致病性测定,鉴定出13种加工型番茄真菌病原及病害。其中早疫病(Alternaria solani)、灰霉病(Botrytis cinerea)、叶霉病(Fulvia fulva)、斑枯病(Septoria lycopersici)、白霉病(Ramularia lycopersici)为甘肃省加工型番茄主要流行性病害,是制约甘肃省加工型番茄发展的主要病害。内丝白粉病(Leveillula brassicae)、柱隔孢菌(Ramularia lycopersici)侵染加工型番茄在国内外未见报道,属新病害。黑斑病(Alternaria brassicae)、果腐病(Fusarium moniliforme)、枯萎病(Fusarium oxysporium)、斑枯病(Septoria lycopersici)、煤污病(Cercospora fuligena)侵染加工型番茄在甘肃省属首次报道。  相似文献   

软包装即食醉鱼制品细菌学品质安全分析   总被引：1，自引：2，他引：1  

王哲恩  许钟  郭全友  杨宪时 《海洋渔业》2007,29(4):349-354

对上海市场常见品牌的软包装即食醉鱼制品感官、理化、细菌学品质状况进行定性和定量研究,并对潜在病原菌安全性进行评价。结果表明,产品水分含量、水分活度、pH和盐分含量分别为43.50%~56.97%,0.93~0.97,6.07~6.73,2.41%~6.63%,差别较大;细菌菌落总数、耐热菌落总数分别是1.8×102~4.2×105cfu/g,38~3 800 cfu/g;厌氧菌落总数和金黄色葡萄球菌均低于10 cfu/g。由细菌总数计数平板分离256株细菌,鉴定残存主要细菌菌群为芽孢杆菌(34.0%)、葡萄球菌(27.3%)、玫瑰小球菌(14.0%),并出现少量的棒状杆菌(5.5%),表明热杀菌强度不足。产品中残存有一定数量的蜡样芽孢杆菌,对其潜在危害有待进一步研究。  相似文献   

Hydrogen cyanide production by soil bacteria: Biological control of pests and promotion of plant growth in sustainable agriculture     

Anju SEHRAWAT  Satyavir S. SINDHU  Bernard R. GLICK 《土壤圈》2022,32(1):15-38

Currently, plant diseases and insect infestations are mainly controlled by the extraneous application of pesticides. Unfortunately, the indiscriminate use of such agrochemicals can cause ecological and environmental problems, as well as human health hazards. To obviate the potential pollution arising from the application of agrochemicals, biological control of soilborne pathogens or insect pests using antagonistic microorganisms may be employed. Certain soil bacteria, algae, fungi, plants and insects possess the unique ability to produce hydrogen cyanide(HCN), which plays an important role in the biotic interactions of those organisms. In particular, cyanogenic bacteria have been found to inhibit the growth of various pathogenic fungi, weeds, insects, termites and nematodes. Thus, the use of HCN-producing bacteria as biopesticides offers an ecofriendly approach for sustainable agriculture. The enzyme, HCN synthase,involved in the synthesis of HCN, is encoded by the hcnABC gene cluster. The biosynthetic regulation of HCN, antibiotics and fluorescent insecticidal toxins through the conserved global regulatory GacS/GacA system is elaborated in this review, including approaches that may optimize cyanogenesis for enhanced pest control. In addition, the effects of bacterially synthesized HCN on the production of indole acetic acid, antibiotics and fluorescent insecticidal toxins, 1-aminocyclopropane-1-carboxylate deaminase utilization and phosphate solubilization may result in the stimulation of plant growth. A more detailed understanding of HCN biosynthesis and regulation may help to elaborate the precise role of this compound in biotic interactions and sustainable agriculture.  相似文献   

斑马鱼在鱼类病原免疫学研究中的应用   总被引：1，自引：0，他引：1  

吴唯维  李盼  柯翎  李素一  陈华  陈叙  林天龙  林晨韬 《福建农业学报》2014,29(6)

斑马鱼全基因组测序已经完成,建立了多个专门的在线数据库,作为模式生物在遗传学、发育生物学等领域已得到了广泛的应用.本文介绍了斑马鱼用于鱼类病原免疫学研究的优点,包括个体发育过程透明、免疫系统较成熟,具有先天性和获得性2种免疫系统;多种鱼类来源的细菌和病毒在成年斑马鱼和胚胎中都能感染和复制,使其成为研究鱼类病原的入侵机制和宿主免疫应答的模式生物.同时,对当前已建立的鱼类细菌和病毒病原斑马鱼感染模型以及在疫苗方面的研究现状作简要概述.  相似文献