Mucosal immune responses to Ichthyophthirius multifiliis in the ocular mucosa of rainbow trout(Oncorhynchus mykiss,Walbaum),an ancient teleost fish

The eye,as a specialized visual organ,is directly exposed to the external environment,and,therefore,it faces constant chal-lenges from external pathogenic organisms and toxins.In the ocular mucosa(OM)of mammals,mucosal-associated lymphoid tissues(MALTs)constitute the primary line of defense.However,the immune defense role of the OM remains unknown in aquatic vertebrates.To gain insights into the immune processes within the OM of teleost fish,we developed an infection model of rainbow trout(Oncorhynchus mykiss)OM using a parasite,Ichthyophthirius multifiliis(Ich).Immunofluorescence,qPCR,and H&E staining revealed that Ich successfully infiltrates the OM of rainbow trout,leading to pathological struc-tural changes,as evidenced by A&B staining.Importantly,the qPCR results indicate an up-regulation of immune-related genes following Ich infection in the OM.Moreover,transcriptome analyses were conducted to detect immune responses and impairments in eye function within the OM of rainbow trout with Ich infection.The results of the transcriptome analysis that Ich infection can cause an extensive immune response in the OM,ultimately affecting ocular function.To the best of our knowledge,our findings represent for the first time that the teleost OM could act as an invasion site for parasites and trigger a strong mucosal immune response to parasitic infection.

First report of Ichthyophthirius multifiliis (Ciliophora:Oligohymenophorea) from Aphanius dispar (Cyprinodontidae) in Iran

Objective:To determine the infection of Aphanius dispar(A.dispar)by Ichthyophthirius multifiliis(I.multifiliis)in Iran.Methods:A total of 97(22 males and 75 females)individuals were collected using dip net from Mehran River,Hormuzgan Province,South of Iran in January 2008.Total length,standard length and weight of the collected specimens were measured to using vernier caliper.Whole body of fish was examined macroscopically for the presence of any blister.For the detection of Ichthyophthirius,the mucus was scraped gently from skin onto a micro slide and stained by Azo-carmine.Prevalence,intensity and abundance of parasite were analyzed.Results:In this study 50(51.55%)specimens including 12 males and 38 females were found infected with I.multifiliis which is an obligate protozoan parasite of freshwater fishes with a direct life cycle and it causes weight loss and mortality in fishes.The infection is known as ichthyophthiriasis or white spot disease,one of the most serious diseases in freshwater fishes.Prevalence,intensity and abundance of parasite in female and male fishes were 50.67%,29.26,14.83 and 54.55%,18 and 9.82,respectively.No sex preference and predilection of body site as microhabitats for this parasite in A.dispar,as well as in three length groups of fish standard length ranging 18-23 mm,23-28 mm and 28-34 mm.However,prevalence and abundance are significantly increased in larger fish than smaller one.Conclusions:This is the first report of I.multifiliis(Fouquet,1876)from A.dispar in Iran and this fish is considered as a new host for the parasite.

20种中草药杀灭离体小瓜虫的药效研究

选用20种不同中草药,研究其不同浓度的水提物对多子小瓜虫(Ichthyophthirius multifiliis)成虫、包囊和幼虫的离体杀灭实验效果。结果显示:0.1 g/L槟榔和乌梅对各个阶段的虫体均有杀灭效果,0.1 g/L大黄和黄芩1 h内对幼虫有杀灭效果,1.0 g/L浓度能杀灭成虫和包囊,表明槟榔、乌梅、大黄、黄芩的杀虫效果相对较好;贯众、乌药、枳壳等13种中药浓度达到10 g/L、50 g/L或100 g/L才具有一定杀虫作用,但效果不很显著;熟地黄、茯苓和黄芪即使浓度达到100 g/L时,也不能杀灭虫体。

滇池金线鲃、西畴金线鲃及其杂交F1代抵抗小瓜虫与车轮虫能力的探究

用小瓜虫（Ichthyophthirius multifiliis）和车轮虫（Trichodina spp.）对滇池金线鲃（Sinocyclocheilus grahami）和西畴金线鲃（S.xichouensis）及其杂交F1代分别进行了两次人工感染实验。18月龄的杂交F1代、滇池金线鲃（Sinocyclocheilus grahami）和西畴金线鲃（S.xichouensis）感染小瓜虫后平均死亡率分别为（50.00±11）%、（56.70±23）%、（80.0±18）%。经方差检验杂交F1代死亡率显著低于父本西畴金线鲃。6月龄杂交F1代、滇池金线鲃、西畴金线鲃感染车轮虫后的平均死亡率分别为（40.56±13）%、（56.11±5）%、（42.78±13）%。经方差检验杂交F1代死亡率显著低于母本滇池金线鲃。在感染小瓜虫和车轮虫后,三种鱼的死亡量均呈现激增后又显著回落的趋势,死亡高峰在第4天至第7天。本次感染实验的小瓜虫和车轮虫主要分布于病鱼体表：躯干分布最多57%-79%,其次为鳍12%-28%,头部分布较少4%-15%。与本研究中车轮虫几乎于鳃丝无分布（0%-3%）不同,有大约10%-20%的小瓜虫分布于鳃丝上。