【摘要】 Giemsa 复合染料中亚甲蓝或天青Ⅱ的曙红盐对显带起重要作用。胰蛋白酶处理植物染色体不仅能消化掉染色体上某些部位的蛋白质,而且还能除去部分 DNA。被处理的染色体经Giemsa 染色或孚尔根反应,能显示出带纹。木瓜朊酶有类似效果。胃蛋白酶处理则不能显带。故推测组蛋白在显带中起较大作用。染色体上异染色质区的核蛋白比常染色质区更能抵抗显带程序中各种处理的影响。染色体臂上有选择地丢失核蛋白是显带的主要原因。更多还原

【Abstract】 Giemsa dye is a complex mixture containing methylene blue,its oxidation pro- ducts-azure Ⅰ,Ⅱ,Ⅲ ,and their eosinate.The results of our experiments have demonstrated that staining with methylene blue alone can give a faint trace of banding as well as azure Ⅰ,Ⅱ.No bands are obtained with eosin.Nevertheless,good chromosome bandings can be often produced by staining with methylene blue-eosinate or azure Ⅱ-eosinate.These data indicate that eosinate has an important effect for the formation of C-banding on plant chromosomes. In our experiments,the treatments of chromosomes with trypsin or pap.ain have also resulted in good C-banding pattern when slides are stained with.Giemsa.We found that the slides untreated with proteinase showed homogeneous intense chromo- some staining and,on the contrary,the slides treated with proteinase led to palestain- ing chromosomes and presenting bandings.It has shown that proteinase,especially trypsin,not only can remove a large amount of chromosomal protein but also can remove DNA and results in C-bandings. Treated properly with trypsin and followed by the Feulgen staining,chromosomes can also produce the C-bandings,but chromosomes treated overtime with trypsin are stained more palely in Feulgen reaction or lead to colourlessness.The above results have further proved that trypsin technique removes large amounts of chromosome DNA and removes less from the C-band regions than from the non-band regions. In this paper we mainly discussed the effects of protein on mechanism of plant chromosome banding.We consider that the production of plant C-banding is pro- bably due to the differential accessibility of nucleoprotein between euchromatin and heterochromatin regions.It brings about selective removal of nucleoprotein from the chromosome arms.We have compared the effect Of trypsin with papain and pepsin on producing bands.Good bands are produced by Giemsa staining Chro- mosomes with trypsin,but no bands are obtained by staining chromosomes treated with pepsin.So the results have expressed that histones are possibly playing more important role in C-bandings.更多还原