It is extremely difficult to gain the fresh specimens from Chinese Paddlefish, so this research gets the formalin-fixed tissues of Chinese Paddlefish(11 individuals) from the Institute of hydrobiology, Chinese Academy of Science. we finally get to have the DNA extracted from formalin-fixed specimens stably by optimizing a series of contrastive experiments, here are the main conclusions as follows:
1. The conventional method is unable to obtain DNA obviously.
2. the alcohol grads method and the TE9.0 for longtime soaking are better to be able to remove the formaldehyde ingredient.
3. the muscle tissues are the best of the liver, heart, muscle and fin tissues; Enhance the TE density, the PH value as well as proteinase K, the SDS density and lengthen the digestion time,these will get the tissues digested easily and protect DNA.
4. The DNA extracted by chloroform - isoamyl alcohol + saturated Nacl solution is less than by direct saturated Nacl salting-out (6mol/L) method
5. Choosing isopropyl alcohol instead of ethyl alcohol to precipitate DNA; We can also get some DNA by re-centrifuging the isopropyl alcohol.
6. The Kit method results are quite different, the effect is unstable, so it is not suitable for the samples from different years or tissues.
7. The amplifications in the different genus and family.we couldn’t get the amplification bands by using 8 pairs of microsatellite primers from Polyodon spathula and 1 pair of microsatellite primer from Chinese sturgeon.
8. Because the DNA quantity is very few, and it includes some complex ingredients, such as the metallic ions and so on, so the reading results are not correct and have the deviation under the spectrophotometer.
9. The results of the DNA extracting from the tissues of the different years (1974-1988) are nearly the same, which indicates that the time for conservation won’t affect the size of DNA, but due to whether the formalin is exposed in the air.