BACKGROUND: Yersinia ruckeri is the etiological agent of enteric red mouth (ERM) or yersinioisis disease, one of the important bacterial diseases in the cultured salmonids. OBJECTIVES: The purpose of present study was detection of gyrA gene (quinolone resistance) in the Y. ruckeri bacterium. METHODS: In this study fish were evaluated in average size 8-12 cm from six rainbow trout farms in Chahar Mahal va Bakhtiyari province (Iran). In each farm 10 fish (totally 60) suspected to yersinioisis were randomly selected; sampling was done from lower part of intestine and cultured on Trpticase Soy Agar (TSA). The mediums were transferred to incubator and kept at 22 °C for 48 hours. Pure colonies which are grown on the mediums were tested by catalase, oxidase and gram staining, then those of gram-negative, catalase positive and  oxidase negative were diagnosed, and cultured on Waltman- Shots medium (as specific medium for Y. ruckeri). These mediums were incubated at 22 °C for 48 h. Colonies that were grown were tested by PCR method for Y.ruckeri detection. Then, in the identified strains of Y.ruckeri gyrA gene were detected by PCR test. RESULTS: The results of bacteriological, biochemical and molecular tests showed that three cases out of total isolates were identified as Y. ruckeri. In all isolates of Y. ruckeri, gyrA gene was identified by molecular test. CONCLUSIONS: Identification of quinolone resistance gene in Y. ruckeri isolates can be the reason of low efficacy of these classes of antibiotics in the aquaculture. ِTherefore, the policy of treatment should be changed specially in enteric red mouth disease.

BACKGROUND: Soybean oil is one of the highly consumed vegetable oil worldwide. Nowadays, usage of genetically modified (GM) soybean seeds for soybean oil production is constantly increasing. The recommended methods for GMO detection are based on analysis of residual DNA in vegetable oil and highly processed food. However, the successful amplification of isolated DNA depends on the efficiency of DNA extraction method. Objectives: The purpose of this study was to apply three different DNA extraction methods for analysis of residual genomic DNA in crude and refined soybean oil to obtain high pure of DNA suitable for DNA amplification. Methods: Extraction methods were developed based on the specific binding of DNA molecules to the silica membrane (column) or resin. The isolated DNA was then analyzed by PCR technique using primer pairs, derived from 18S rRNA and 5.8S rRNA gene and soybean lectin gene. Results: The results showed that amplifiable DNA could not be extracted from crude/refined soybean oil in method 1. In method 2, by pre-treating of oil with PBS and subsequent precipitation with Isopropanol, the amplification was not observed but OD260 was decreased. In method 1 and 2 the DNA was not pure enough to be amplifiable. To remove more effectively contaminant, method 2 was combined with chloroform extraction as method 3. The extracted DNA from all examined oil samples could be amplified. ConclusionS: We believe that the purity of DNA in samples is decisive for amplification and not necessarily the low amount of DNA in samples. Method 3 can be determined as a suitable method for the isolation of the pure DNA.