Dissertation > Agricultural Sciences > Aquaculture, fisheries > Fisheries Protection > Pest and Disease Control of the crustaceans

Indentification the Bacterial Pathgeon of the Milk Disease of Cultured Swimming Crab Portunus Tritubercularus (Portunidae) and Study on the Histopathology

Author HuangZengRong
Tutor WangGaoXue
School Northwest University of Science and Technology
Course Preventive Veterinary Medicine
Keywords Three trituberculatus Vibrio alginolyticus Vibrio harveyi Pseudomonas putida Milk sickness 16SrRNA Epidemiological survey
CLC S945
Type Master's thesis
Year 2006
Downloads 198
Quotes 3
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The warts swimming crab (Portunus tritubercularus) in 1981 and has been classified as our marine aquaculture object. Since the 1950s, China's marine life scientists have made some research of its succession. Continues to heat up, makes in three trituberculatus around breeding as three trituberculatus fast growth, environmental adaptability, less disease, high market prices, price stability at home and abroad. With the continuous expansion of the scale of farming and the intensification of the continuous improvement of various diseases followed, especially bacterial diseases, to the three trituberculatus aquaculture caused serious economic losses. By 2004-2005 in Zhoushan City, Zhejiang Province trituberculatus breeding and holding culture field sample collection and epidemiological investigation found a crime against the very serious bacterial disease, infection quickly, the incidence of a wide range, once the disease is very will soon spread to the entire pool. The disease mostly occurs in September to next February, the fattening period from September to November is the peak incidence. The disease acute onset, short course, a large area in a short time of death. The high incidence of about 60%, the mortality rate is higher, is essentially 100%, often caused by acute death. The main symptoms of the disease is slow in the early activities, difficulty breathing, slow response to external stimuli or substantially unreactive, dived at the bottom. As the disease progresses, breathing more difficult, often due to lack of oxygen surfaced or climbed up the bank. Late thoroughly appetite waste must, the appendages joint film at visible whitish muscle, cut off appendages, muscles liquefied natural dropping into a milky white liquid. Open the carapace, part of the gill filaments black sand or soil deposition, some gill filaments, each component of the internal organs have not see the effort sinus and digestive system probably only visible shape, liver, pancreas, gonads dissolved into a milky white hemolymph becomes milky white, such as milk fluid substances, naturally shed. In accordance with the onset of symptoms and the local farmers to the habits of the people, we will call the \From suffering from \Physiological and biochemical characteristics test showed that the isolated strains of Vibrio alginolyticus (Vibrio alginolyticus), Vibrio harveyi (Vibrio harveyi) and Pseudomonas putida (Pseudomonas putida) is very similar, further three pathogens 16sRNA gene sequences for PCR amplification, sequencing and phylogenetic tree was constructed, the results showed strains S1, S2, and A1, respectively, and Vibrio alginolyticus, Vibrio harveyi and Pseudomonas putida natural clustering, the closest relationship , similarity of up to 99.80%, 99.44% and 99.79%, respectively. Together, these results can be identified as S1, S2, and A1 bacteria Vibrio alginolyticus, Vibrio harveyi and Pseudomonas putida. Artificial infection test results show that the three bacteria isolated the three trituberculatus, Chinese mitten crab and Kunming mice were significantly pathogenic role. Which the artificial infection incidence trituberculatus symptoms similar to the natural disease. Susceptibility test results show that the three bacteria are highly sensitive to ciprofloxacin, ofloxacin, pefloxacin sand magnitude; oxazole sodium sulfamethazine sulfamethazine sodium, sodium sulfadiazine sensitive . Take the artificial infection incidence trituberculatus were gills, claws muscle, ambulatory leg muscles, swimming foot muscles, liver, pancreas and other organs for conventional paraffin for histopathological analysis, the pathological features: liver and pancreas dirty area of ​​necrosis, is severe, cell lysis disappear, local visible karyopyknosis the fragmentation or disintegration. Gill cavity expansion,

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