The Studies Of Chromosome Banding Technology And DNA Contents Of The Topmouth Gudgeon (Pseudorasbora Parva)

The topmouth gudgeon (Pseudorasbora parva), is a small cyprinid fish that distributes widely in the littoral zones of freshwater habitats. It grows quickly and reaches sexual maturity in the first year of its life. It shows wide tolerance to environmental conditions and can easily be cultivated in both indoor and outdoor environment. Therefore, it can be cultivated as a potential bio-indiactor. This study aims to understand P. parva’s genetic background, and lay the cytogenetics foundation for cultivating it as a new bio-indicator. In this study, the karyotype, Ag-NORs, C-banding of chromosome, and DNA contents of P. parva were discussed, and the results were as follows:1. Karyotypic analysisTwo methods used for metaphase chromosome preparations. One was a routine method including intraperitoneal injection with PHA and colchicine, and the other one was the short-term fin tissues cultivation method. The results showed that the diploid chromosome number was50, and the karyotype was2n=18m+22sm+10st, NF=90. While the secondary constriction, heterosome and satellite chromosome were not observed by routine giemsa’s staining method.2. Ag-NORs bandingWe uesed the method of intraperitoneal injuection with PHA and colchicine for metaphase chromosome preparations but without giemsa’s staining. A pair of Ag-NORs was found on the end of no.23chromosome short arm by silver dying, and the NORs were polymorphic, while no Ag-NORs combination had happened in this fish.3. C-bandingWe uesed the method of intraperitoneal injuection with PHA and colchicine for metaphase chromosome preparations also without giemsa’s staining. The results showed that C-bands were located mainly in the terminal and centromere regions of chromosomes, while only a few in the interstitial regions. In particular, most of the short arm on chromosome no.23showed strong positve C-bands. 4. DNA contentsFlow cytometry was used to determine the DNA content in blood, muscle, fin, gill, liver, kidney and gonad of P.parva. There were some differences in DNA contents in seven tissues. The highest and lowest tissue of DNA contents were the muscle and kidney, gill, which reached3.20±0.07pg and3.05±0.08pg, respectively. We used blood’s DNA contents as the diploid cellular DNA contens of P. parva, which was3.17±0.10pg.5. Cell cycleFlow cytometry was also used to determine the cell cycle in blood, gill, liver, kidney and gonad of P. parva. All tissues showed the cell cycle, the ratio of the time phase of G0/G1in gonad and liver was the lowest, and the two tissues showed higher cell proliferation index that was17.81%and13.19%, respectively. While the lowest cell proliferation index was detected in gill that was merely6.54%. There were also differences regarding to the time phase of cell cycle in different tissues.