[Influences of cycle index and volume on sensitivity of DNA detection].
OBJECTIVE
To explore the feasibility of improving the sensitivity of DNA detection by increasing the PCR cycle index and decreasing the volume of amplifying system.


METHODS
The DNA of semen were collected from 10 healthy irrelevant volunteers, and were quantified to 50, 40, 30, 25, 20, 15, 10 pg/microL, separately. All samples were then amplified in 10, 5, 3 microL volume and at 28, 30, 32, 34, 36 cycles, respectively. 3130 genetic analyzer was used to detect 15 autosomal STR loci.


RESULTS
Under the situation of 28 cycles and 3 microL volume, samples which achieved > 40 pg/microL could be correctly typed. Under the situation of 10, 5, 3 microL volume, samples which achieved > 20 pg/microL could be correctly typed at 34 cycles. When increasing the index to 36 cycles, they could not be correctly typed because of the non-specific band.


CONCLUSIONS
DNA detecting sensitivity can be improved to a certain extent by increasing the cycle index and decreasing the volume of amplifying system.
School of Forensic Medicine, China Medical University, Shenyang 110001, China. zhangluzhaoyang@sohu.com
Lu
L
Zhang
Bao-Jie
BJ
Wang
Mei
M
Ding
Zi-Qing
ZQ
Lin
Hao
H
Pang
Jia-Xin
JX
Xing
Jin-Feng
JF
Xuan
D004247:DNA / Q000032:analysis* / Q000235:genetics; D016172:DNA Fingerprinting / Q000379:methods*; D005240:Feasibility Studies; D053803:Forensic Genetics / Q000379:methods; D006801:Humans; D057230:Limit of Detection; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods*; D012661:Semen / Q000737:chemistry*; D012680:Sensitivity and Specificity; D020080:Tandem Repeat Sequences
D004247:DNA