Chemoattraction And Reproduction In Vitro Of Cryptocaryon Irritans

Cryptocaryon irritans belongs to the Protozoa, Ciliophora, Oligohymenophorea. Hymenostomatia, Hymenostomatida, Ophryoglenidae, Cryptocaryon, is widely distributed in tropical, subtropical waters. C. irritans can infect many kinds of seawater aquaculture fishs:Latescalcarifer, Lutianusargentimaculatus, Fugu rubripes, Pseudosciaena crocea, Sciaenopsocellatus, Weever, Trachinotus ovatus, Epinephelussp, Pagrosomus major, Sparus macrocephlus, Rhabdosargus sarba, Lutjanus erythropterus. Which infectivity is very strong, As the rapid growth of intensive maricultured and eutrophication in partly sea aquacultural areas has been aggravated drastically, water in marine aquaculture areas had circulated unfreely, the outbreak of “while spot disease” of marine fish has became a terrible problem which often leads to mass mortalities and cause heavy economy losses..Despite the “while spot disease” has been included into the secondly-class epidemic disease of aquatic animal, no efficacious strategy is available to prevent and control this epidemic. For a better understanding to C. irritans which collect from Pseudosciaena crocea of Ningde, and offer some useful information for the disease control, the reproduction of C. irritans in vitro as well as in vivo was investigated, then the chemotaxis of the protozoan was probed into in the present paper.The results of in vivo reproduction showed that: the protozoan finish its life cycle in 1 week at 26℃, and adequate tomonts was collected. To get tomonts at the same phase, the infected Trachinotus ovatus were removed to another aquarium at 2 h post-infection. The tomonts was collected conveniently by laying dishes at the bottom of the aquarium.In vitro experiments showed that the theronts of C. irritansis can grow in L-15 and FBS liquid culture medium and bass serum can stimulate the growth of theronts better than bass mucus.The growth condition of theronts within 300 μL bass serum in 2 ml culture medium is better than the ones in 100 μL、200 μL and 400 μL bass serum respectively. Besides, adding bass gill filaments will restraint theronts growing. These theronts can grow to a certain extent, most can not develop well and all can not develop into cyst, but the experiment of theronts will provide a valuable reference for the in vitro of C. irritans.The mode of our laboratory was applied to study deeply in C. irritans, the result show that: chemoattraction of C. irritans theronts reaches highest after treated 30 minutes and the chemoattraction ration arises to the highest between 26 to 28 centigrade. The serum and mucus of various marine fishes, even including some freshwater fish have strong chemoattraction to theront and the muscle homogenates shows some chemoattraction, while stomach, intestines and liver homogenates as well as small molecular substances,(for example, carbohydrates, amino acids and sugarson) shows no chemeattraction to theront. The chemoattraction to theront was highly increased when compared serum which was collected from infected fishes with the serum without infection(p<0.01). The test also found that nine kinds of the Chinese herbal medicine showed strong repellent effect at the concentration of 0.2 g/L while only six(Chinese gall, Rheum officinale, chinaberry, Betel nut, Polygonum cuspidatum and Cyrtomium fortunei) of them had obvious repellent effect when the concentration was reduced to 0.05 g/L.