| Saprolegniasis, also called Dermatomyucosis, is a kind of common aquaculture diseasesinfected by filamentous fungi. All kinds of aquatic animals will be infected bySaprolegniasis at each stage during the whole life story which from eggs to the adultthroughout the year, because of its wide distribution, widely disseminated, and no verystrict selective for the host. It’s very vulnerable for swimming Saprolegniasis sporesattach to Aquatic animals with wound. Once the Saprolegniasis spores infected to theskin of fish, spores can get nutrition from the host to grow, which will lead the fish toinflammation and necrosis, burden, swimming disorders, anorexia, thin and died at soon.It’s one of the most difficult problems of fish disease for Saprolegniasis control andprevention in a long time. Aquaculture has suffered a huge of economic losses by thefrequent occurrence of Saprolegniasis.AS many researchers from many countries arecommitted to the research work for prevention and control of Saprolegniasis, it’s veryimportant for us to build the disease model of Saprolegniasis.This paper briefly reviewed and summarized the latest research on the present model ofanimal diseases, status and progress of Saprolegniasis research, and some discussion ofthe principles and applications of Saprolegniasis model. We established an efficientstrong pathogenic strain from different sources of Saprolegniasis by infectionexperiment; optimized the generation and germination environmental factors of thecertain strain; selected a suitable fish by compared the different kinds of common fishwhich were infected easily by Saprolegniasis; set the infection conditions withHistopathology observation and clinical examination; set up the Saprolegniasis diseasemodel through the conditions parameters optimization and the reliability data analysis;estimated and screened the different resistant drugs for Saprolegniasis prevention andcontrol.1We selected six different Saprolegniasis pathogenic bacteria, established the HP as theefficient strong pathogenic strain from different sources of Saprolegniasis by infectionexperiment. Saprolegniasis: HP (separated from the yellow Sang fish eggs), JL(separated from the PengZeJi eggs), XJ (separated from the sturgeon muscle), QL(separated from the brocade carp skin), YW (separated from the grass carp tail), XL(separated from the shrimp eggs). We can find the filamentous hyphae form the surfaceof infected eggs by microscopic observation. For the morphological characteristics were basically the same as the original separation strains, we can preliminary judge thatstrains JL, HP, XJ, QL, YW, XL were pathogenic strain of Saprolegniasis. From theexperimental results, we established the HP as the efficient strong pathogenic strain,because the infection rate of HP higher than other5strains of bacteria.2We optimized the generation and germination environmental factors of the HP strainthrough different culture conditions (temperature, pH, source of carbon and nitrogensource nutrition) according to the characteristics of asexual reproduction. Theexperimental results showed: the optimum temperature and pH for the generation ofspores was20°C and7;the optimum temperature and pH for the germination of sporeswas20°C and7. It’s not high nutritional requirement for the germination of HP strainsspores: HP germination could be continued in distilled water. However, the sporegermination can be promoted in the rich nutrition conditions in advance3We selected the grass crap as a suitable fish by compared4different kinds of commonfish (grass crap; silver carp; common carp; crucian carp) which were infected easily bySaprolegnias: the grass crap group can reach (93.3±4.25)%, even100%of artificialinfection rates with high sensitivity and stable which showed that the standard deviationwas low, the coefficient of variation of small by F test. The group of silver carp;common carp showed a high infection rate, respectively (73.3±5.25)%and(86.7±4.35%)%, while the infection rates of crucian carp group was relatively low:(46.67±15.55)%. The experimental results showed that the grass crap could be used asan ideal Saprolegnias susceptibility fish.4, Histopathology observation and clinical examination of grass crap which infected bySaprolegnias, this paper set up the Saprolegniasis disease model through the conditionsparameters optimization and the reliability data analysis: single one conditions oftemperature changed/wounded/Saprolegniasis soaked on the grass carp forSaprolegniasis artificial infection can’t be successful. So the sufficient condition ofSaprolegniasis artificial infection to fish was multifactorial by the breeding environmentor the conditions change. The results by F-test showed: the infection rate of grass crapgroup was stable (P>0.05) with the coefficient of variation of6.82%and9.22%,respectively, which declared that there was a good reproducibility, reliable method.5, According to the Saprolegniasis disease model, this paper also estimated andscreened the different resistant drugs for Saprolegniasis prevention and control. Theresult showed: there was a significant difference (P <0.05) at each group in drugs andcommercialization drugs. The cure rate was increasing gradually as the drugconcentration upwards in each group. Different kinds of drugs performed differenteffect to modeling grass carp Saprolegniasis disease model (p <0.05): the cure rate ofsulfur methane and formalin were the highest, respectively (37.8±17.1)%and (28.8± 13.5)%; the cure rate of Isothiazolinelcetone, JinYi tabor were high, respectively(37.8±17.1)%and (28.8±13.5)%; while dual Sodium acetate only to reach the (13.3±3.3)%. Different kinds of commercialization drugs performed different effect tomodeling grass carp Saprolegniasis disease model (p <0.05): the average cure rate ofMeiTing was the highest,(44.4±15.0)%(p<0.05); Junduxiao and Shuimeiling werehigh, respectively (34.4±15.3)%and (32.2±18.9)%, not a significant difference toShuimeijinII (28.9±15.0)%(p>0.05). Among of these, the cure rate rate of MeiTingwith4g/m3, can reach60.0+/-20.0)%.This article selected six different Saprolegniasis pathogenic bacteria, established the HPas the efficient strong pathogenic strain from different sources of Saprolegniasis byinfection experiment; optimized the generation and germination environmental factorsof the HP strain through different culture conditions (temperature, pH, source of carbonand nitrogen source nutrition) according to the characteristics of asexual reproduction;selected the grass crap as a suitable fish by compared4different kinds of common fish(grass crap; silver carp; common carp; crucian carp) which were infected easily bySaprolegnias; set the infection conditions with Histopathology observation and clinicalexamination of grass crap which infected by Saprolegnias. This paper set up theSaprolegniasis disease model through the conditions parameters optimization and thereliability data analysis. According to the Saprolegniasis disease model, this paper alsoestimated and screened the different resistant drugs for Saprolegniasis prevention andcontrol. |
