A nuclear division between mitosis and amitosis

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1、A nuclear division between mitosis and amitosis-M-Mitosis and Multiformity of Nucleus in the Pelargonium zonale CellLi MingyinInstitute for Gardenscience, Mianyang Normal University, Mianyang, Sichuan (621000) Department of plant breeding, Humboldt University of Berlin, Lentzeallee 55-57, 14195 Berl

2、in, GermanyE-mail: mingyinliAbstractThe nuclear division, according to the appearance of chromosomes or not, would be divided into two models: indirect mitosis and direct amitosis. One division between amitosis and mitosis has not beenreported. During our experiments with a mutated clone of the hapl

3、oid plant “Kleiner Liebling” in Pelargonium zonale 5/74/2, a nuclear division in polyploidized epidermis cells was found that showed neither the typical amitosis characteristics nor the typical mitosis. The new division contains the constriction of the amitotic division and the visible chromosome of

4、 the mitotic division. Thus, we consider that it is a mixture of the amitosis and mitosis. It can call the m-mitosis. With the m-mitosiscould explain the formation of different multiform nuclei.Keywords: Pelargonium, cell division, mitosis, amitosis, m-mitosisFlemming（1882) has divided the nuclear d

5、ivision in one cell cycle of eukaryotes into two models: mitosis and a-mitosis (non-mitosis). The mitosis is a continuous sequence of events with moving of chromosomes with the help of the spindles, namely in prophase, metaphase, anaphase and Telophase (Rieder & Khodjakov, 2003). In typical mitosis,

6、 the exact duplicated genetic material in parent nucleus can be divided into two identical daughter nuclei ( Scholey , et al. 2003). In this way all daughter cells are genetically the same as the parent cells. Therefore, the mitosis is regular nuclear division for a lifecell.The incontestable amitot

7、ic nuclear division procedure was directly observed by Macklin (1916) for the first time in healthy chicken cells in in-vitro culture. In amitosis, the nucleus is divided directly into several parts without the appearance of visible chromosomes ( Rieger et al. 1991) and starts with a transversal con

8、striction of the nucleolus ( Chen & Wan, 1986). With the absence of the chromosomes, the amitosis can easily distinguish from the mitosis. Grynfeltt divided the amitosis in to three phases: protophase, Mesophase and telicophase (Grynfeltt, 1931). Amitosis is observed in animal and plant cells( Wilso

9、n & Leduc, 1950; Torre & Martin, 1975; Miller, 1980; Valente, et al. 1998; Bhattathiri,2001). A division between amitosis and mitosis has not been reported( Bucher, 1971 ). But in this study we have observed a division that contains some character of mitosis and some of amitosis.1. Material and Meth

10、odsThe shoots of the mutated clone 5/74/2 of the haploid plant “Kleiner Liebling” of Pelargonium zonale were treated with 0,1% colchicin solution for 6 hours, after fixing 24 hours in carnoy II, they were soaked in ethylenglycolmonoethylether, 96% ethanol, propanol and butanol, sequentially each for

11、24 hours（Li，2007 ）. Then the shoot tip samples were polymerized in an embedding solution,containing 100 ml Technovit 7100 (Germany) and 1 g dibenzoylperoxid in dark for 24 hours. Then they were carefully placed in embedding capsules with embedding mixture (10 ml above solution and 1 ml dimetylsulfox

12、id) and solidify for 24 hours. The embedded shoot tips were sectioned to 8 -10 m with a rotation microtom.The slices were stained using the procedure by Bcke (1989) for 10 second to 1 minute in diluted(1:1 with distilled water) toluidin blue solution (60 ml of 1% toluidin blue water solution was mix

13、ed with 30 ml of 2.5% natriumcarbonat water solution and 10 ml of 70% alcohol) and washed with- 4 -running water. After drying, the good stained slides with tissue slices were covered with a cover slip using DPX solution (Fluka).2. Character of the division between mitosis and amitosisIn cytological

14、 investigation of the polyploid epidermal cells of the muted haploid clone Pelargonium zonale Kleiner Liebling 5/74/2, we have observed the different figure in U, W shapes that they areconsidered between forms of a nuclear division (Fig. 1).ABCDFigure. 1: Multiform nucleus in Pelargonium zonal clone

15、 5/74/2.A. The nuclear membrane with the chromosomes begins to constrict from a side of the nucleus to form a contracted furrow. B. The constriction expands to continuously the opposite site of the nucleus to form a nucleus in a U-shape. C. Two nuclei with the nuclear membrane, nucleoli and chromoso

16、mes are in one cell. D. Conjoined quadruplets are associated on the nucleus.The morphology of the nuclear division in figure 1 is neither identical with the one in mitosis that nuclear division with the moving of the chromosomes nor amitosis, in which no visible chromosomes appears. The division pro

17、cess comprises the constriction furrow of the amitotic division and the visible chromosomes of the mitotic division, but without the separation of sister chromosomes is observed. Torre and Martin (1975) had observed the similar division that amitosis with chromosomes after the tissue of the Allium a

18、re treated with the Ethidium bromide. It is a mixture of the amitosis and mitosis or a division between the mitosis and amitosis.3. Discussion3.1 Possible process of the m-mitosisThe morphology of this nuclear division is easily distinguished not only from mitosis, but also from amitosis. Also we su

19、ggested to called m-mitosis instead of amitosis by Torre and Martin (1975). The u-shaped and multiform nuclei were considered as middle stage of this nuclear division. According to the change of nuclear state at the nuclear division in our observation (figure, 1) and to the phase evidence of mitosis

20、 (Rieder, 2003) and amitosis (Grynfeltt, 1931), we suggest that the m-mitosis consists of three phases: m-prophase, m-mesophase and m-telophase. At the basis of study the transitional forms of the nuclei of previous and later stages from the nuclear figures, we tried toconstructed the m-mitosis proc

21、ess as follows in figure 2:CFigure: 2. Possible procedure of the m-mitotic nuclear divisionm-Prophase: the chromosomes are condensed into visible chromosomes and the nucleolus disappears(Fig.2A), but the nuclear membrane remains in the cell.m-Mesophase: The nuclear membrane is constricted somewhere

22、else to form a contracted furrow (Fig.1A, 2B) in which the chromosomes are arranged not at the equator of the cell as in metaphase of mitosis. The contracted furrow of original nucleus develops further in a u-shape (Fig. 1B, 2C) until it constricted continuously into two independent parts.m-Telophas

23、e: the nuclear constriction is completed and two new daughter nuclei are formed. The daughter nuclei are still close to each other in the middle of the cells (Fig.1C, 2D).If the division is disturbed temporarily in mesophase of the m-mitosis, the nucleus cannot divide into two independent parts, and

24、 result a u-figure nucleus. The u-shape nucleus can enter into the second cycle of m-mitosis, in which each arm of the u-shape nucleus can constrict further into two parts, so that it establishes a conjoined quadruplets which four nuclei are associated parallel with the chromosomes and nuclear membr

25、ane (Fig. 2E).3.2 Function of the m-mitosisThe all stages of the nuclear m-mitotic division show the appearance of chromosomes, but did not show the disappearance of the nuclear membrane, which is different from c-mitosis (in which the nuclear membrane disappeared) and is similar with characteristic

26、 of endomitosis (Geitler,1939). During endomitosis, the chromosomes condense and double, the nuclear membrane is not disappeared and the sister chromatids separation take place only within the nuclear envelope without nuclear division (Tschermak-Woess, 1971). The m-mitosis differs essentially from e

27、ndomitosis by the division of the nucleus. Endomitosis give arises nuclear growth and endopolyploidization (Joubes & Chevalier, 2000), but the m-mitosis lead to the reduction of the nuclear volume and reduce the cell ploidy level if cytokinesis follows after m-mitotic division. Therefore the m-mitos

28、is cycle could be considered as a nuclear depolyploidization of the endomitotic enlarged nucleus. It did not show the separation of sister chromosomes. The mechanism and function of the chromosomes in this model of nuclear division is open.Reference1 Bhattathiri, V. N. 2001, Amitotic cell divisions

29、and tumour growth: an alternative model for cell kinetic compartments in solid tumours. Oral Oncology 37, 288-2952 Bck, P. 1989, Romeis-mikroskopische Technik. 17. Auflage , Urban & Schwarzenberg Verlag,.3 Bucher, O. 1971, Zum Problem der Amitose. in Der Zellkern, Handb. der allgemeinen Pathologie.

30、H. W.Altmann, Ed. Springer Verlag, Heideberg, pp. 626-699.4 Chen, Y. Q. ,B. K. Wan, 1986, A study on amitosis of the nucleus of the mammalian cell. I. A study underthe light and transmission electron microscope , Acta Anat 127, 69-765 Flemming, W. 1882, Zellsubstanz, Kern- und Zellteilun . Leibzig,

31、Vogel.6 Geitler, L. 1939, Die Entstehung der polyploiden Somakerne der Heteropteren durch Chromosomen- teilung ohne Kernteilung，Chromosoma 1, 122.7 Grynfeltt, E. 1931, Amitoses et noyaux gemines dans les revetements malpighiens，C. r. Ass. Anat. 26,215-2278 Joubes, J. , C. Chevalier, 2000, Endoredupl

32、ication in higher plants. Plant Mol Biol 43, 735745 43, 735-7459 Li，Ming-Yin，2007，A Method for Direct Determination of Ploidy Level of Somatic Cells in DifferentLayers of Cytochimeral Tissue of Pelargonium zonale，Scientia Silvae Sinicae，7：125-12710Macklin, C. C. 1916, Amitosis in cells growing in vi

33、tro. Biol. Bull. 30, 445-46711Miller, R. 1980, Amitosis and endocytogenesis in the fruit of Malus sylvestris，Annals of Botany 46, 567 -575.12Rieder, C. L.A. Khodjakov, 2003, Mitosis through the microscope: advances in seeing inside live dividingcells. Science 300, 91-96.13Rieger, R., A. Michaelis, M

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35、16Tschermak-Woess, E. 1971, Endomitose，in Der Zellkern, Handb. der allgemeinen Pathologie. 2/2/1 H.W. Altmann, Ed. Springer Heidelberg, pp. 569-62517Valente, P. ,W. Tao, J.-P. Verbelen, 1998, Auxins and cytokinins control DNA endoreduplication anddeduplication in single cells of tobacco ，Plant Scien

36、ce 134, 20721518Wilson, J., E. Leduc, 1950, Abnormal Mitosis in mouse liver， American Journal of Anatomy 86, 51-73一种介于有丝分裂和无丝分裂的细胞分裂方式天竺葵细胞的混合分裂和多型细胞的形成李明银绵阳师范学院园林科学研究所，四川绵阳（621000） 德国柏林洪堡大学农业-园林学院植物育种所，Lentzeallee 55-57, 14195, Berlin摘 要：根据细胞核分裂中染色体的出现与否，Flemming 将细胞核分裂分为有丝分裂和无 丝分裂两种类型。介于两者之间的分裂方式未见报道。在单倍体天竺葵突变株系 5/74/2 的多倍体表皮细胞中，一种既不同于无丝分裂，又不同于有丝分裂的细胞核分裂方式被发 现。这种分裂方式包含了无丝分裂的核缢缩和有丝分裂染色体可见的特点。本研究认为，它是一种介于有丝分裂和无丝分裂之间的混合分裂方式，并由此形成稀有的多型核细胞。 关键词：天竺葵；细胞分裂；有丝分裂；无丝分裂； 混合分裂