Pathological findings in rainbow trout (Oncorhynchus mykiss Walbaum, 1792) ewperimentally infected with Yersinia ruckeri

Bu çalışmada deneysel olarak Yersinia ruckeri ile enfekte edilen gökkuşağı alabalıklarında patolojik bulguların incelenmesi amaçlandı. Bu amaçla toplam 42 adet [1 kontrol grubu (10 balık) ve 1 deneme grubu (32 balık)] gökkuşağı alabalığı kullanıldı. Daha sonra deneme grubundaki balıklara 3 x 106 cfu/ml bakteri içeren 0,1 ml'lik Yersinia ruckeri serotip I (R0072) susu intraperitoneal olarak, kontrol grubuna ise aynı dozda serum fizyolojik intraperitoneal olarak verildi. Uygulamayı takiben 4. ve 26. günler arasında doğal infeksiyon sonucu ölen ya da öldürülen balıkların sistematik nekropsileri yapılarak makroskobik ve mikroskobik bulguları incelendi. Makroskobik olarak akut formda, özellikle yüzgeç tabanlarında, gözler ve anüs çevresinde, hava kesesinde ve solungaçlarda hiperemi ve kanamalar gözlendi. Kronik formda, deri renginde açılma veya koyulaşma ile karaciğerde sarımsı-gri renk değişiklikleri belirlendi. Ayrıca böbrek ve dalağın kontrol gruplarına göre daha koyu renkli ve küçük oldukları görüldü. Mikroskobik olarak, akut formda, sekonder lamellerde ödem, hiperemi, kanama, epitellerde dökülmeler ile böbreklerdeki lenfoid hücrelerde belirgin azalmalar saptandı. Dalakta görülen en önemli bulgu is.e fokal nekrozlar idi. Kronik formda ise solungaçlarda interlameller hücrelerde hiperplazi, karaciğerde yağlanma ile böbrekte çok sayıda iri yapılı ve çentikli çekirdekli lenfoid hücre proliferasyonları dikkati çekti. Bu araştırma, Türkiye'de Yersinia ruckeri ile gökkuşağı alabalıklarında deneysel olarak yapılan ilk patolojik çalışmadır.

Deneysel olarak Yersinia ruckeri ile enfekte edilmiş gökkuşağı alabalıklarında (Oncorhynchus mykiss Walbaum, 1792) patolojik bulgular

The aim of this study was to evaluate the pathological findings in rainbow trout experimentally infected with Yersinia ruckeri. For this purpose, 42 [1 control group (10 fish) and 1 experimental group (32 fish)] of rainbow trout were used. Yersinia ruckeri serotype I (R0072) at a concentration of 3 x 106 cfu/ml (0.1 ml per fish) was intraperitoneally injected into the experimental group, whereas the control group was subjected to the same volume of sterile saline. Following the intraperitoneal injection, between 4 and 26 days, fish that died due to natural infection and those killed were necropsied and macroscopic and microscopic findings were determined. Macroscopically, in the acute form, hyperemia and hemorrhages were observed, especially at the base of the fins, around the anus and eyes, on the swim bladder and in the gills. In the chronic form, dark pigmentation or depigmentation of the skin and yellow-grayish discoloration in the liver were noted. In addition, the kidney and spleen were dark in color and smaller than those observed in the control fish. Microscopically, in the acute form, edema, hyperemia, hemorrhage and desquamation of the epithelial cells in the secondary lamellae and a significant decrease in the numbers of lymphoid cells in the kidney were seen. In the spleen, focal necrosis was the most important microscopic finding. In the chronic form, hyperplasia of the interlamellar cells of the primary lamellae, fatty changes in the liver and many large mononuclear cell proliferations with slightly incised nucleus in the hemopoietic tissue of the kidney were observed. This is the first pathological study on rainbow trout experimentally infected with Yersinia ruckeri in Turkey.

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