Comparative Study On Amitosis In Three Genus Of Characeae

Charophyta has one outline and three items(Sycidiales,Trochiliscales,Charales). Now there's only Characeae of Charales,which has 6 genus and about 400 species.There's more than 150 species have been reported in China. This text chooses three genus Charophytes of Characeae: Nitella papillata, Nitellopsis obtusa and Chora connivens to study their amitosis.Take the node cells, branchlet cells,internode cells and rhizoid cells of the three genus Charophyte which are cultured with tap water in natural light and room temperature,to be scrubed clearly, fasted in Carnoy's fixation in room temperature when the chlorophyl leave, and the stined by Giemsa 4',6-diamidino-2'-phenylindole (DAPI)to observe their nucleus. As there are some difference on the surface in three genus Charophyte textural: Nitella papillata has pectin on the surface, Nitellopsis obtusa has lots of calcium and Chora connivens has cortex ane calcium, so there are different ways to study them by staining in Giemsa and we have found right ways after many experimentations. Otherwise, as there are cortex cells on the surface of Chara connivens , it's hard to study them by staining in Giemsa. The experimentation by staining in DAPI to studr the three genus Charophyte is the same and convenience. The internode cells of Chara connivens can be studied after peeling off the cortex cells. We can have statistic of the amitosis by the way of staining in DAPI. The result shows that the division of the cell nucleus in different qrowing periods and different growing parts are amitosis. No mitosis has been found. The cells most are multinucleate, and also the internode cells are mononucleate or double-nucleate. The nucleus are different in shapes and sizes. The rhizoid is resemble as fibre in high plants. The shapes of the rhizoid nucleus near the stem and in rhizoid nodes are regular while in other places are anomalistic. When in amitosis, the chromatin don't concentrate, the karyotheca don't disaggregate, and the dividing places are not fixed. The daughter nucleus are different in sizes and shapes, in consistent with the results we group have studied in Nitellopsis obtusa. The observe and statistic of the amitosis in three genus Charophyte show that the amitosis in different parts of the same charophyte and in the same parts of different algae are different. In particular, we discover the node cells of Nitellopsis obtusa are mononucleate or double-nucleate with division of constriction type and dissection type. While the node cells in other two charophyte are mononucleate with no amitosis; The node cells in rhizoids of the three genus charophyte are mononucleate while only in Nitellopsis obtusa there's anomalistic dissection type in the rhizoid node cells. So, the node cells and rhizoid node cells of Nitellopsis obtusa are obviously different with the other two charophyte. The reason why the amitosis of the three genus charophyte are different maybe related with the factors in cells. The other two specialities are: first, the nucleus in rhizoids near the stems are round and regular, while in other rhizoids are anomalous. The rhiziods near stems maybe transformed from the stems embeded in the mud and the nucleus in general keep intrinsic shapes while in the new rhizoids anomalous nucleus produce. The reason and mechanism should be studied later. Second, in similar size internode cells and cortex cells, the proportion of dividing nucleus to the total amount of nucleus was almost in negative correlation. It confers certain size charophyte cells can maintain the amount of nucleus. It indicates that charophyte cells have special physiological phenomenon.