In two-line hybrid rice, hybrid seed production often encounters self-or sib-seed con-tamination because of the incomplete male sterility of female line, While in multiplication of male sterile seeds,it has the problem of fertile seed contamination originating from pollination with ex-otic pollen or from mechanically mixed seed.

With the widel application of medical devices that manufactured by utilizing animal tissues in clinical fields, great attention have been given by the authorities to the risk of viruses and transmissible agents originating from animal tissues and the potential risk to the human body.