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Being put forward more than ten years ago, DNA barcoding technology has now become a hotspot in the related domestic and international fields of food safety and animal protection in species identification, which can characterize the species in a fast and accurate way to provide scientific evidence for the judicial practice. This paper summarizes the principle, development and application prospects of DNA barcoding technology.
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Objective To investigate the relationship between Ct value of mice liver and postmortem interval (PMI) under various ambient temperatures. Methods mice were stored at 10℃, 15℃, 20℃, 25℃ and 30℃ after execution, and total RNA was extracted from mice liver every 6 hours (PMI 6h to 72h). The levels of 18s rRNA were examined using real-time PCR. The results were expressed by cycle threshold (Ct) value to explore relationship between PMI and Ct value, and the interpolation functions were established to estimate PMI. Results In each group, Ct value increased with PMI increased. Surface equation was obtained after interpolation analysis on temperature range 10℃~30℃. The three-variable quintic surface equation was f(x, y)=-426.9+30.82x+44.48y-1.297x2-1.837xy-1.388y2+0.034 38x3+0.038 17x2y+0.038 67xy2+0.028 77y3-0.000 612 9x4-3.897e-7x3y-0.001 223x2y2+0.000 256 6xy3-0.000 537 4y4+3.606e-6x5-2.846e-6x4y+1.009e-5x3y2-3.439e-6x2y3-2.556e-7xy4+2.664e-6y5(r2=0.999 4). Conclusion The rule of Ct value changes at ambient temperature complied with three-variable quintic surface equation distribution. Measurement of interpolation function may be used for PMI estimation at ambient temperature.
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[ ABSTRACT ] AIM: To investigate the expression and clinical significance of bone morphogenetic protein 3 (BMP3) in hilar cholangiocarcinoma tissues.METHODS: Thirty cases of hilar cholangiocarcinoma specimens were col-lected.The expression of BMP3 at mRNA and protein levels in the tumor tissues and paracancerous tissues was detected by real-time PCR and Western blot.The hilar cholangiocarcinoma paraffin-embedded specimens (n=103) were collected. The protein expression of BMP3 was determined by immunohistochemical method, and the relationship of BMP3 protein ex-pression with clinical pathological characteristics was evaluated.RESULTS:In the 30 patients with hilar cholangiocarcino-ma, the expressions of BMP3 protein and mRNA in 22 cases of tumor tissues were significantly decreased compared with the adjacent normal tissues.The results of immunohistochemistry showed that 87 cases were negative and 16 cases were weakly positive in all 103 cases of hilar cholangiocarcinoma.The expression of BMP3 protein was associated with the tumor TNM staging, lymph node metastasis and tumor differentiation (P<0.05).CONCLUSION:BMP3 gene might be inhibited in human hilar cholangiocarcinoma.The down-regulation of BMP3 gene might be associated with the carcinogenesis and devel-opment of hilar cholangiocarcinoma.