Objective The purpose of this study was to investigate the feasibility of short tandem repeat(STR) genotyping of cell free DNA in plasma for individual identification and paternity testing. Methods EDTA-Na2 DNA anti-coagulant blood samples were collected from 36 unrelated healthy volunteers,and both DNA in leukocytes and cell free DNA in plasma were extracted respectively using phenol-chloroform method. Target DNA in blood cells and plasma were amplified using regular STR typing and fluorescent multiplex STR assay separately,accordingly,the PCR products were analyzed by polyacrylamide gel electrophoresis and capillary electrophoresis. Results Using either normal PCR-STR or fluorescent multiplex STR assay,the consistent STR genotyping results were detected with similar efficiency for cell DNA and plasma DNA samples from the same individual. Conclusion Cell free DNA in plasma samples can be used as useful biological samples for STR genotyping,which can be applied to individual identification and paternity testing in forensic practice.

The reform for the laboratory operational mechanism includes laboratory management system reform and experimental teaching reform.The author made some explorations and research to the operational mechanism and management pattern of university laboratory of forensic biology,then presented some ideas.

To introduce tutorial system for undergraduate in the forensic biology teaching is an important measure of educational reform of forensic medicine.The article presented some schemes and experiences about the practice of tutorial system for undergraduate in the forensic biology department of Kunming Medical College.

Objective To study the correlation between the polymorphisms of NR3C1 gene and aggressive behavior in Yunnan Han population.Methods Five SNPs of the NR3C1 gene (rs6190,rs6191,rs6198,rs41423247 and rs56149945) were genotyped in 194 unrelated prisoners who committed violent-crimes and 301 healthy controls using improved Multiplex-ligase-detection reaction(iMLDR) method,and the data were statistically analyzed with the SPSS19.0soflware and PHASE2.1platform.Results Single locus analysis showed that the allelic distribution of rs6191and rs41423247did not show significant differencesbetween the control groupand the aggressive-behavior group as well as the robbery sub-group and intentional injury sub-group.However,significant difference was foundin the rs41423247 genotype distribution betweencontrol groupand robbery sub-group (p=0.048).In addition,there were no significant differences for the four haplotypes between the control group,the attack group,the robbery subgroup and the intentional injury subgroup.Conclusion These findings indicate that rs41423247 polymorphism of the NR3C1gene might play a role in susceptibility to aggressive behavior and rs6191 polymorphismmay not be correlated withaggressive behavior.

Objective To study the genetic polymorphism of 20 autosomal short tandem repeats(STR)loci in Yunnan Han population. Methods The 20 STR loci(D3S1358,D1S1656,D6S1043,D13S317,Penta E,D16S539,D18S51,D2S1338,CSF1PO,Penta D,TH01,vWA,D21S11,D7S820,D5S818,TPOX, D8S1179,D12S391,D19S433 and FGA)which were included in the PowerPlexR21 System kit were genotyped in 1085 unrelated Han individuals living in Yunnan province using multiplex amplication. PCR products were separated and analyzed by the AB 3130 automatic genetic analyzer and GeneMapper ID v3.2 software. Forensic parameters of each locus were calculated by Modified-Powerstates software. Results All the studied loci except for TH01 and TPOX were highly polymorphic. The observed heterozygosity(Ho)ranged from 0.6130 to 0.8743. Match probability(PM)ranged from 0.0179 to 0.2030. Power of discrimination(DP)ranged from 0.7970 to 0.9821. Probability of exclusion(PE)ranged from 0.3067 to 0.7432. Paternity index(PI)ranged from 1.2919 to 3.9766. Polymorphism information content(PIC)ranged from 0.5598 to 0.8958. No deviation of the Hardy-Weinberg equilibrium was observed. Conclusion The studied 20 STR loci were highly polymorphic in Yunnan Han population and could be used in forensic individual identification and paternity testing practice.

Epigenetics is the study of heritable changes in gene expression other than the changes in the underlying DNA sequence. Such changes include DNA methylation,genomic imprinting,X chromosome inactivation and non-coding RNA regulation. Recent progresses on epigenetics offer new ideas to tackling these problems in forensic science,including determination of the necessary allele in paternity,identification of fetal paternity testing in embryonic period,discrimination of identical twins,origination analysis of tissue,and individual age estimation. This review focuses on the main concept of epigenetics and its application in the field of forensic science.

Forensic biology is a main subject of forensic medicine.With the rapid development of science and technology,the courses should be constantly improved.New teaching mode has come into being application of multimedia technology in theoretical lessons,case teaching,independent completion of experimental lessons,which is thanks to the constant reinforcement of teaching staff and the reform of course content and teaching methods.

The article elaborated the standard of quality control,open service management system and requirements for system construction of forensic biology laboratory,which is to share laboratory recourses and advance the healthy and sustainable development of the laboratory.

Based on the experience of experimental teaching reform of forensic biology,the article made a systematic exposition about the measures and experience of the research and practice of the reform from the following aspects: aim of the reform,priority of the reform and specific measures.By reforming experimental teaching methods,the students' interests and performance record have been significantly improved.

Objective To genotype mixed samples with next generation sequencing and evaluate its prospects in forensic DNA application. Methods Three mixed biological samples from rapes cases and their reference samples were collected. DNA was extracted using the MagAttract M48 DNA Manual Kit(200). The ForenSeqTMDNA Signature Prep Kit was used for library preparation, and next generation sequencing was performed on the MiSeq FGx system. The ForenSeqTMUniversal Analysis v1.2.1 software was used for data analysis. NGS-based STR results were compared with CE-based genotypes. Results A single length polymorphic STR allele in the mixed profile could be recognized as two sequence polymorphic STR alleles from different donors, which would assist mixed profile analysis. Such phenomenon was observed in D3S1358, D9S1122 and D13S317 in this work. Conclusion Our results suggested that precision STR genotyping of mixed samples based on NGS can provide more information and hints for mixed STR profile separation.