Aphanomyces invadans and ulcerative mycosis in estuarine and freshwater fish in Florida

In the spring of 1998, the Florida Fish and Wildlife Research Institute received numerous reports of lesioned or ulcerated fish primarily from the St. Lucie Estuary on the southeast coast of Florida, an area known since the late 1970s for lesions of the ulcerative mycosis (UM) type. From these and archived reports, as well as others received from different areas of Florida, we documented that diseased specimens had randomly distributed skin ulcers (usually reddened or hemorrhagic) with raised irregular margins and, in some cases, deeply penetrating hyphae in the surrounding muscle tissue. Since 1998, 256 fish (comprising 18 species) with ulcerative lesions (from 15 different locations) were confirmed with hyphae in fresh squash preparation or by histological evaluation. Squash preparations revealed nonseptate, sparsely branching, thick-walled hyphae; histological sections revealed mycotic granulomas in the dermis that occasionally penetrated into the skeletal muscle. These pathological characteristics were consistent with UM caused by the oomycete Aphanomyces invadans in Southeast Asia, Japan, Australia, and the United States. For specific identification, six isolates from ulcerated fish were cultured and prepared for molecular characterization using established diagnostic methods. Ribosomal RNA gene sequence analysis identified three isolates as Aphanomyces invadans, one as the oomycete Achlya bisexualis, and two as the ascomycete Phialemonium dimorphosporum. A more extensive survey of 67 ulcerated skin samples from fish collected between 1998 and 2003 was performed using a polymerase chain reaction assay specific for Aphanomyces invadans. Of these, 26 (38.8%) samples from seven fish species and nine collection locations were positive. Confirmation of UM associated with Aphanomyces invadans represents new host records in Florida for the sheepshead Archosargus probatocephalus, striped mullet Mugil cephalus, white mullet Mugil curema, silver perch Bairdiella chrysoura, black drum Pogonias cromis, largemouth bass Micropterus salmoides, and American shad Alosa sapidissima.     

Detection of Aphanomyces invadans and epizootic ulcerative syndrome in the Murray‐Darling drainage

Epizootic ulcerative syndrome was diagnosed, and the presence of Aphanomyces invadans confirmed, from an outbreak of clinical disease in wild‐caught bony bream (Nematalosa erebi) from the Darling River near Bourke, in New South Wales, Australia, during 2008. This confirms a significant extension of the agent beyond its historical range.     

Development and standardization of a monoclonal antibody-based rapid flow-through immunoassay for the detection of Aphanomyces invadans in the field

A monoclonal antibody-based flow-through immunoassay (FTA) was developed using a nitrocellulose membrane placed on the top of adsorbent pads enclosed in a plastic cassette with a test zone at the center. The FTA could be completed within 10 min. Clear purple dots against a white background indicated the presence of Aphanomyces (A.) invadans. The FTA limit of detection was 7 µg/mL for A. invadans compared to 56 µg/mL for the immunodot. FTA and polymerase chain reaction (PCR) could detect A. invadans in fish tissue homogenates at a 10^-11 dilution compared to a 10^-8 dilution by immunodot. In fish suffering from natural cases of epizootic ulcerative syndrome (EUS) collected from Mangalore, India, FTA and PCR could detect A. invadans in 100% of the samples compared to 89.04% detected by immunodot. FTA reagents were stable and produced expected results for 4 months when stored at 4~8℃. This rapid test could serve as simple and cost-effective on-site screening tool to detect A. invadans in fish from EUS outbreak areas and in ports during the shipment of live or frozen fish.     

猪──鱼结合型生态牧业

本文陈述了猪粪的营养学特性及施猪粪水体存在的主要食物链，阐述了该水体的主养鱼种类及适宜的猪鱼配比，并讨论了养鱼水体受粪力影响因素及猪粪养鱼的社会安全性等问题。     

Pathogenicity studies with the fungi Aphanomyces invadans, Achlya bisexualis, and Phialemonium dimorphosporum: induction of skin ulcers in striped mullet

Based on isolations from naturally infected fish in Florida, we investigated the role of the fungi Aphanomyces invadans, Achlya bisexualis, and Phialemonium dimorphosporum in the etiology of ulcerative mycosis (UM) in striped mullet Mugil cephalus. We injected healthy striped mullet subcutaneously with secondary zoospores of four oomycete isolates: two concentrations (50 and 115 zoospores/mL) of SJR (an endemic isolate of Aphanomyces invadans in American shad Alosa sapidissima from the St. Johns River); two concentrations each of CAL (25 and 65 zoospores/mL) and ACH (1,400 and 2,000 zoospores/mL; endemic isolates of Aphanomyces invadans and Achlyva bisexualis, respectively, in striped mullet from the Caloosahatchee River); and two concentrations of the ascomycete culture MTZ (2,500 and 3,500 zoospores/mL; endemic isolate of P. dimorphosporum from whirligig mullet M. gyrans in the Matanzas Inlet). All fish injected with either concentration of SJR developed granulomatous ulcers after 8 d and died within 21 d. Eighty percent (8/10) of fish injected with the high dose of CAL developed ulcers after 13 d and died within 28 d, but only 30% (3/10) of fish injected with the low dose of CAL developed ulcers. Four of the ulcerated fish died within 28 d, and the remaining fish were terminated after 32 d. Fish injected with zoospores of Aphanomyces invadans developed ulcers that were grossly and histologically similar to those observed in naturally infected striped mullet with UM from several estuaries or rivers in Florida. These hemorrhagic skin ulcers were characterized by myonecrosis and the presence of mycotic granulomas. None of the fish injected with ACH, MTZ, or sterile water developed ulcers. This study fulfilled Koch's postulates and demonstrated that ulcers could be experimentally induced in striped mullet after exposure via injection to secondary zoospores of an endemic Florida strain of Aphanomyces invadans.     

Aeromonas hydrophila Isolated from Wild Freshwater Fish in Croatia

Aeromonas hydrophila was recovered from fish living in lake Vrana on the Croatian island of Cres. The occurrence of the bacterium in the fish was assessed and related to gross signs of disease and findings at necropsy as a potential health hazard for fish. Isolated bacteria were subjected to morphological, physiological, biochemical and antibiotic susceptibility tests. A total of 26 A. hydrophila isolates were obtained. There was a clear seasonality, as no isolates were recovered in the summer months. Most of the isolates were sensitive to all the antimicrobials used in the study except novobiocin and penicillin G. Affected fish manifested haemorrhages over the skin, in the liver, kidney and swim bladder, spleen infarcts, fatty liver, ascitic fluid and swollen haemopoietic tissues. A. hydrophila does not appear to pose a major threat for the fish in the lake at present but under unfavourable and stressful conditions it could seriously compromise fish health.     

Establishment and Characterization of Seven Continuous Cell Lines from Freshwater Fish

Abstract

Seven continuous cell lines were established from salmonid and nonsalmonid fishes. Salmonid cell lines derived from rainbow trout Oncorhynchus mykiss and chum salmon O. keta were designated RTE and RTE-2 (rainbow trout embryo), RTT (rainbow trout tail), and SEH (“sake” or chum salmon embryo head). Nonsalmonid cell lines derived from pond smelt Hypomesus olidus, chevron snakehead Channa striata, and goldfish Carassius auratus were designated WF-1 (“wakasagi” fin), SHH (snakehead heart), and EPG (epithelioma papulosum of goldfish), respectively. Optimum growth for most of the cell lines was observed in Eagle's minimum essential medium buffered with sodium bicarbonate (26 mM) or a combination of sodium bicarbonate (8.9 mM) and tris (16 mM). Likewise, most of the cell lines showed optimum growth at the lowest NaCl concentration tested (0.116 M). Optimum growth temperatures ranged from 15 to 20°C for the salmonid cell lines and from 15 to 30°C for nonsalmonid cell lines. Except for RTT, the cell lines were heteroploid. Eleven fish viruses were used to test the susceptibility of these cell lines. Cell lines derived from salmonids developed cytopathic effects (CPE) when infected with 10 of the 11 fish viruses tested, except for RTT, which produced CPE with only 8 of the fish viruses. Six fish rhabdoviruses used in this study elicited a pronounced CPE when inoculated into nonsalmonid cell lines EPG, WF-1, and SHH. Among the new cell lines, RTE-2 showed the best potential for the isolation of fish viruses.     

淡水鱼虾华支睾吸虫囊蚴感染情况调查

采集吉林省白城地区镇赉县周边6个鱼塘的各种鱼类,用直接压片镜检法和人工消化法分别对采集回来的麦穗鱼感染华支睾吸虫囊蚴的情况进行统计调查,结果表明,感染率最高、感染强度最大的鱼塘是四方坨六分场。随即对四方坨六分场鱼塘中各种鱼类华支睾吸虫囊蚴感染情况也采用同样方法进行调查,结果显示,感染率最高的是麦穗鱼、银飘鱼、尖头鱥,均为100%;其次是细鳞鱼,为80%;其他种类的鱼虾均未检测到有华支睾吸虫囊蚴寄生。     

淡水鱼类线虫病的病原及其扫描电镜观察

从浙江省的窖湖、灵湖、凤湖等水库捕捞的大银鱼、花Hua、鸟鳢鱼、黄颡鱼、鲶鱼、沙塘鳢等6种鱼类体内获得大量的红色线虫，对其进行光镜和扫描电镜察，根据其形态特征和流行病学资料，鉴定为膨结科胃瘤线虫未定种(Eustrongylides sp．)。此线虫在大银鱼、花Hua、沙塘鳢体内寄生国内尚属首次报道。     

大宗淡水鱼的生物学特性及养殖水环境的调控

论述了大宗淡水鱼生物学特性、水体中各种因素对大宗淡水鱼养殖的影响,并提出了对大宗淡水鱼养殖水环境调控的相应措施,阐述了水体环境对大宗淡水鱼养殖的重要性.     

Modeling the Decision-Making Behavior of Fishers in the Reef Fish Fishery on the West Coast of Florida

When, where, and how a commercial vessel fishes determines the temporal and spatial placement of the data they are legally bound to supply to management agencies. Data provided by commercial fishing vessels are used in assessments to infer fish population abundance. Fisher decision-making may also allow fishers to dissipate the benefits of regulations and affect expected management outcomes. Decisions about participation, site choice, and trip termination were modeled for commercial fishers in the Gulf of Mexico. Vessel logbook data were used to parameterize discrete choice models for each decision. A questionnaire of vessel captains (N = 40) helped inform model structure. Results suggested that participation and site choice decisions may be nested, and are affected by expected revenue, regulations, fish price, wind speed, vessel characteristics, and fuel price. Trip termination was influenced by regulations, wind speed, and catch relative to fish hold capacity. Assessment and management implications are discussed.     

黑龙江省扎龙自然保护区丹顶鹤食源地淡水鱼囊蚴的初步检测研究

为保护丹顶鹤健康生长、繁衍生息,保证扎龙自然保护区自然生态的和谐发展,对保护区周边淡水鱼进行随机采样,解剖,通过直接压片和人工消化两种方法进行吸虫囊蚴检验。通过检测发现丹顶鹤有通过食用生鱼感染棘口吸虫的风险,并指出每年的4—7月份是扎龙自然保护区丹顶鹤寄生虫病防控的关键时期。检测结果为丹顶鹤寄生虫病的防治提供了参考依据。     

ERIC-PCR对山东省东平湖4种常见淡水鱼肠道菌群多样性的分析

分析山东省东平湖常见4种淡水鱼肠道菌群多样性的差异。采用ERIC-PCR(enterobacterial repetitive intergenic consensus PCR,ERIC-PCR)技术,得到鱼肠道菌群的ERIC-PCR指纹图谱,并用NT-SYS-pc(Version 2.10)软件进行分析。成功建立了山东省东平湖常见4种淡水鱼肠道菌群的ERIC-PCR指纹图谱,了解肠道菌群的差异。草鱼和鲢鱼肠道菌群较为相似,与鲫鱼、鲤鱼肠道菌群差异较大。表明4种淡水鱼类的肠道菌群的组成有明显的差别,食性差异大的鱼类之间肠道菌群差异更明显。     

家免体表霉菌病的诊断及其治疗试验

通过对家兔体表霉菌病的诊断,选择了四种药物进行治疗试验,结果皮癣宁、癣菌灵、灰黄霉素、克霉唑的治愈率分别为80%、80%、60%、20%;其结果表明皮癣宁和癣菌灵对兔体表霉菌病有显著疗效.     

家兔体表霉菌病的诊断及其治疗试验

通过对家兔体表霉菌病的诊断，选择了四种药物进行治疗试验，结果皮癣宁、癣菌灵、灰黄霉素、克霉唑的治愈率分别为80％、80％、60％、20％；其结果表明皮癣宁和癣菌灵对兔体表霉菌病有显著疗效。     

禽霉菌病及霉菌毒素中毒的诊治

禽霉菌毒素中毒是养禽过程中常见的疾病，多是由饲料、垫料发霉变质而引起，在潮湿多雨地区易发，最近我国一些地区特别是南方多雨，农户应引起注意。若不能及时诊治可影响家禽的生长发育，严重者甚至引起死亡，给养殖场、养殖户造成巨大损失。以下两篇文章从理论到具体防制该病都做了详细的叙述，以供大家参考。