Study On The Biological Characteristics Of Cryptocaryon Irritans On Pseudosciaena Crocea

In the east China sea in recent years, breeding appeared in a danger pseudosciaena crocea serious pandemic, the main symptoms of diseased fish body surface, fins and gill flap covered with white spots the size of parasites and cysts,visible, said "white spot" disease, the pathogen of Cryptocaryon irritans.The parasite can cause abnormal fish activity, epithelial hyperplasia, difficulty breathing and mechanical damage, and then bring the secondary infection of bacteria. However, domestic for Cryptocaryon irritans pathogen biology and disease detection technology research is relatively small, there is still no effective control of Cryptocaryon irritans on pseudosciaena crocea technical methods.This in-depth study of the biological characteristics of Cryptocaryon irritans on pseudosciaena crocea in order to prevention and control research and implementation of the original Cryptocaryon irritans surveillance, detection and to provide an experimental theoretical basis.Cryptocaryon irritans on pseudosciaena crocea isolation and passage:risk of irritation from the large yellow croaker Cryptocaryonosis successfully isolated the pathogen surface, and the establishment of a set of large yellow croaker as the host of Cryptocaryon irritans passage system. The system cycle is short, the method is simple, collect higher yield of parasites, Cryptocaryon irritans for follow-up study of biological characteristics of the protection given to experimental material.Temperature and salinity on Cryptocaryon irritans tomont hatching rate:incubation temperature is17℃～27℃Cryptocaryon irritans tomont at the hatching rate increases with the temperature gradually increased,27℃at maximum95%. When the temperature rose to32℃when the hatching rate decreased to65%,37℃when the hatching rate of only15%. Suitable for Cryptocaryon irritans tomont hatch wide range of salinity in the15%o～35%o of salinity, the hatching rate can reach95%, the optimum salinity of20%o～25%o.Cryptocaryon irritans tomont and theront during the development of microscopic and submicroscopic observation:the early development of tomont in the0～24h, the surface smooth, wall thin, smooth wall, often attached to some of the rod-like bacteria, the inner layer number dense layer (thickness1.7μm). Development of medium-term (24h～48h), tomont rough surface structure, wall thickness up to5μm or more, stratified clear at this stage food vacuole, such as fat body and the Golgi apparatus in cysts scattered throughout the cytoplasm and mitochondria, Golgi apparatus and rough endoplasmic reticulum increased significantly. Development of late (48h-72h), looming development of larvae within the tomont were oval or spherical. Continued thickening of the wall at this time, the thickness of10μm or more, but becomes obvious stratification between, including the outer wall was sticky and soft. Theront off the tomont after0-8h, and ciliary body of the worm body is more dense around the cell structure is complete, active and strong; theront off the tomont after8h-16h of Cryptocaryon irritans larvae significantly reduced the number of its body cilia, cilia showing off body hair matrix; theront off the tomont after16h-24h, the larvae of the cell body and cilia almost entirely off the mouth, the cell size in a serious recession has basically lost activity.Drugs on the in vitro immersion Cryptocaryon irritans tomont and theront of:potassium permanganate concentration of9mg/L larvae began to die soak12minutes,24minutes to effectively kill all the larvae, concentrations of less than9mg/L for larvae without killing effect. Hydrogen peroxide concentration of120μl/L have better killing effect,58min to kill all. Copper sulfate at lmg/L～25mg/L concentration, the effect on the larvae without killing, but the copper sulfate concentration of20mg/L or more can completely inhibit the development of cysts. Low salinity water to kill larvae of the effect of decreasing as salinity, kill, the better,6.0%o seawater15min to completely kill the larvae, but its effect is not as good as killing the larvae cysts obvious. Formalin in70μl/L concentrations32min larvae all died, and its concentration in100μl/L or more than50%of cysts killing effect.According to Cryptocaryon irritans18S-ITS2sequence, design of two pairs of specific primers. We have to establish a Cryptocaryon irritans detection and optimization of LAMP reaction conditions. The method is highly specific which Cryptocaryon irritans detection sensitivity is10-7ng/μlDNA.Sick fish tissue and water samples by detecting and analyzing, indicating a good prospect.