Method for obtaining male individual sperm cells from seminal fluid vaginal fluid mixed spots

Abstract

The invention belongs to the technical field of forensic medicine, and relates to a method for separating cells by immunomagnetic beads, in particular to a method for separating male individual spermcells from seminal fluid vaginal fluid mixed spots by utilizing an immunomagnetic beads technology. The method comprises the following steps: step 1, mixing male seminal fluid and female vaginal fluidaccording to the principle of informed consent; step 2, coupling the sperms by using a biotin labeled ACRBP antibody, and enriching and collecting sperm cells of a male individual by using avidin coupled magnetic beads and an external magnetic field. and step 3, carrying out PCR amplification and capillary electrophoresis so as to perform genotyping on the STR locus. The method provided by the invention can effectively determine the source of the individual DNA in the male individual seminal stain from the gene level, greatly simplify the step of identifying the tissue source of the body fluid or its spots at the criminal investigation scene, and can provide an accurate scientific basis for defining case properties, determining criminal suspects, convicting and sentencing.

Description

technical field [0001] The invention belongs to the technical field of forensic medicine and relates to a method for separating cells by immunomagnetic beads, in particular to a method for separating sperm cells of male individuals in semen-vaginal fluid mixed spots by using the immunomagnetic bead technology. Background technique [0002] In rape cases, the mixed semen-vaginal fluid spots remaining in the victim's body, clothing, and bed sheets are one of the common and important first-hand inspection materials. The different types of cells in the mixed plaque were separated by different technical means to obtain the sperm of the male individual, and then the sperm was lysed to obtain the suspect's DNA, the STR pattern analysis was carried out, and the possible typing was obtained by statistical methods. At present, the technology of DNA typing of suspects using STR profiles is relatively mature, but on the issue of how to effectively obtain sperm from male suspects, many m...

AI Technical Summary

Problems solved by technology

In this case, STR results can exclude unrelated individuals, but cannot serve the purpose of personal identification

2) Differential cracking method, this method is better for mixed spots that are not polluted and contain more sperm, but the extraction effect for difficult mixed spots that are seriously polluted on site is not ideal; The interference of inhibitors such as pigments and pigments will reduce the amplification efficiency or fail to amplify, so the typing effect is poor

3) Laser capture microdissection technology, this method needs to find intact sperm cells under a microscope and cut and enrich them. Due to the limitation of the number of sperm obtained, sometimes it cannot meet the quantitative requirements of PCR detection sensitivity

In addition, in some old or degraded samples, the tails of sperm cells are often broken and lost, and it is difficult to identify typical sperm cells under a microscope, making it difficult to operate

4) It is very difficult to separate and test the male substances by conventional analysis methods. Sometimes even if the typing results are obtained, it often shows that the typing of each mixed component coexists with each other, or the phenomenon of female components showing a dominant amplification, which makes the result difficult. analysis becomes complicated

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