Objective To study genomic polymorphic DNA and genetic distance of 7 species of ticks.\ Methods\ Ticks used in this study were Dermacentor nuttalli, D.silvarum, Haemaphysalis qinghaiensis, H.formosensis, H.punctata, Amblyomma testudinarium, and Ixodes ovatus. DNA extracts of the 7 species of ticks were amplified by random amplified polymorphic DNA (RAPD) and PCR technique using 5 primers with different arbitrary single chain polynucleotide sequences. DNA fingerprint maps were analyzed and the genetic distance among 7 species of ticks were counted. \ Results \ The amplified products of the 7 species of ticks by RAPD all showed their specific DNA band. The average genetic distance among them was 0\^71. Conclusion RAPD can differentiate the 7 species of ticks.

This study sought to elucidate the effect of mechanical strain on the differentiation of mesenchymal stem cells into osteoblasts. Under the conditons of inducing osteoblasts, Immunohistochemical methods and RT-PCR technology were applied in osteogenic supplements medium to detect: (1) the expression of Alkaline phosphatase (ALP), Type I collagen (COL I ), Osterx (Osx) and Osteocalcin (OCN) mRNA, with cyclic strain (3%, 0.5 Hz) applied for 15 min, 30 min, 1 h, 2 h, 4 h, 3 d, 7 d, 14 d; (2) the expression of Osx mRNA and OCN mRNA with 3% strain for 1 h. The results showed: (1) ALP mRNA expression was higher at 7 days; COL I mRNA expression was greater obviously at 7 days and 14 days than that at 3 days and that of the unstrained cells; (2) the expression of Osx mRNA was up-regulated after 15min by strain stimulation,which was significantly increased at 30 min and 1 h in the unstrained cells. The expression of OCN mRNA was not affected in the unstrained cells at 15 min, whereas strain could promote the expression of OCN mRNA at this period. The expression of OCN mRNA was more obviously upregulated in the strained cells at 30 min and 1 h when compared with that in the unstrained cells; (3) the strain (1% and 3%) significantly promoted the expression of Osx mRNA; 10% strain had a little effect on Osx mRNA expression. The expression of OCN mRNA was up-regulated by 3% strain, whereas it had little effect at 1% and 10% strain. In summary, mechanical strain can promote the differentiation of mesenchymal stem cells into osteoblasts.
Animals ; Bone Marrow Cells ; cytology ; Cell Differentiation ; Cells, Cultured ; Mechanoreceptors ; physiology ; Mechanotransduction, Cellular ; physiology ; Mesenchymal Stromal Cells ; cytology ; Mice ; Osteoblasts ; cytology ; Osteocalcin ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Sp7 Transcription Factor ; Stress, Mechanical ; Transcription Factors ; genetics ; metabolism