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The purpose of this study was to assess the stability of mRNA and rRNA for evaluation of viability for Xanthomonas citri subsp. citri (Xcc). Total RNA from Xcc suspensions subjected to different stress treatments (high temperature or chemical treatment with sodium orthophenylphenate at different concentrations) was extracted at different time periods post-treatment (0, 3, 24 and 48h) and analysed by quantitative real-time reverse transcription PCR (Q-RT-PCR). Primers were designed from selected fragments of rRNA and mRNA from genes involved in bacterial fitness, virulence or general metabolic mechanisms (gumD, rpfB, avrBs2 and gyrB). After stress treatment, only a 445-bp fragment from the gumD mRNA was detected in live Xcc cells specifically, whereas other RNA fragments, as well as DNA targets, were detected in both viable and nonviable cells. Statistical analyses demonstrated that the amount of some transcripts from genes involved in xanthan synthesis, pathogenicity factor regulation and DNA processing was significantly reduced after lethal treatments. The amplification of the 445-bp product from gumD mRNA was demonstrated to be useful for the detection of viable Xcc; the product was detected specifically from viable bacteria on leaf and citrus fruit surfaces and in citrus canker lesions. Instability of long RNA fragments can be used as a practical tool for the study of survival of citrus canker bacteria or for diagnostic purposes when the presence of viable bacteria needs to be confirmed. © 2011 The Authors. Plant Pathology © 2011 BSPP.

Background: Most of colorectal cancers (CRC) have originated from intestinal polyps. Evaluating of the expression level of genes that are involved in tumors growth and development, may consider as diagnostic factor of malignancy in the polyps. AXIN2 regulates the level of nuclear β-catenin in a negative-feedback loop there by being a negative regulator and target gene at the same time. The aims of current study were to examine the expression level of the AXIN2 in the colonic polyps and its linkage with the pathological features of the polyps. Methods: In the present analytical-descriptive study, the investigated population was chosen from the cases with colonic polyps that referred to the Gastroenterology and Liver Diseases Research Center, Taleghani Hospital, Tehran, Iran, from October 2014 to April 2015. Forty four biopsy polyp samples and 10 normal tissue samples were collected, as well as the demographic and clinical properties of the patients and the expression level of AXIN2 gene was quantified by Real-time PCR. The outcomes were analyzed by the ABI Prism 7500 Sequence Detection System (SDS) software, version 2.1.0 (Applied Biosystems Inc., Foster City, CA, USA) and GraphPad Prism, version 3 (GraphPad Software Inc., La Jolla, CA, USA) Also, the expression changes of the intended gene in target groups were compared with the normal tissues using the 2-ΔΔCt equation. Results: The data showed enhanced level of the expression of AXIN2 gene in the colonic polyps in comparison to the normal tissues (RQ>2), which was significantly upper in adenoma polyps compared to the hyperplastic group (P=0.015). Also, unlike the rectum, the AXIN2 gene activity in colon area was higher than normal tissue. Conclusion: The results of the current study show that the expression pattern of AXIN2 gene, was markedly changed during the transformation of the normal tissue to polyp. The increased expression level of this gene could be applied as a diagnostic marker in dissociation of the adenoma polyps from hyperplastic ones. On the other hand, the location of the polyps modulates the AXIN2 gene function. Taking together, evaluating the changes of AXIN2, has a precise diagnostic value in the CRC related studies.