Method for judging blood stain formation time in forensic medicine by detecting RNA degradation degree

Abstract

The invention discloses a method for judging blood stain formation time in forensic medicine by detecting RNA degradation degree. According to the invention, 18S rRNA is selected as a basis, and a 44bp short fragment, a 149bp middle fragment and a 305bp long fragment are respectively used as target sequences to design primers. Real-time fluorescent quantitative PCR (qPCR) detection is carried outby using the three primers with short, medium and long fragments. The method comprises the following steps that: qPCR reaction is carried out on the standard substance subjected to gradient dilution to construct a standard curve; a Ct value is obtained through qPCR amplification detection; and the initial template copy number can be quantified by substituting the Ct value into a standard curve. Along with the increase of time, the probability of successful amplification of the long-fragment target sequence is the lowest, and the probability of successful relatively stable amplification of medium fragments and short fragments is high. And the integrity of the RNA in the human blood stain sample is judged by calculating the ratio of the initial copy numbers of the long fragment and the shortfragment and the ratio of the initial copy numbers of the middle fragment and the short fragment. By analyzing the linear relationship between the RNA integrity and the time, a technical means is provided for researching the blood stain retention time, the death time, the injury time and the like.

Description

technical field [0001] The invention relates to a specific primer combination for detecting the degree of RNA degradation in human bloodstain samples and a method for using the combination to detect the degree of RNA degradation to infer the formation time of bloodstains, belonging to the technical fields of forensic science, forensic science and molecular biology detection. Background technique [0002] The formation time of bloodstains has always been one of the important research topics in the field of forensic science. At the scene of some violent crimes, bloodstains can often be seen as biological evidence. By scientifically interpreting the bloodstains that appeared at the crime scene and studying the distribution and shape of the bloodstains at the scene of the case, the criminal's trajectory and behavior can be used to judge the nature of the case. After the blood leaves the human body, it will degrade. The longer the blood leaves the body, the more serious the degr...

AI Technical Summary

Problems solved by technology

[0005] The second relative quantitative ratio method to judge the degree of degradation also has obvious disadvantages

Variables such as genetics, health, or medical care may alter their relative starting ratios, making accurate judgments about the extent of RNA degradation versus time

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