MITOTIC INSTABILITIES IN TETRAPLOID, HEXAPLOID, AND OCTOPLOID BROMUS INERMIS

1977 ◽  
Vol 19 (3) ◽  
pp. 531-536 ◽  
Author(s):  
Geok-Yong Tan ◽  
G. M. Dunn

Mitotic irregularities were observed in the root tip cells at three ploidies, tetraploid (4x), hexaploid (6x), and octoploid (8x), of smooth bromegrass (Bromus inermis Leyss.). These included endomitosis, fragments, chromosomes excluded from the spindle, anaphase bridges, laggards and micronuclei, at different stages of mitosis. High frequencies of anaphase irregularities were detected at the 4x and 6x levels. The commercial octoploid was more stable. Intraplant variations of some morphological characters in smooth bromegrass may be attributed to chromosomal instabilities in somatic cells.

1999 ◽  
Vol 47 (3) ◽  
pp. 153-156 ◽  
Author(s):  
Wusheng Jiang ◽  
Donghua Liu

The effects of different concentrations (10−5-10−2M) of lead nitrate on root growth and nucleoli in root tip cells of Brassica juncea L. were investigated. The results showed that lead nitrate has a stimulatory effect on root growth at lower concentrations, and an inhibitory effect at higher concentrations. Pb has toxic effects on chromosomal morphology, including c-mitosis and anaphase bridges, and on nucleoli, causing some particulate silver-stained material scattered in the nuclei and inducing irregularly shaped nucleoli. Once the nucleolus was affected, the root growth almost or completely stopped.


1994 ◽  
Vol 42 (3) ◽  
pp. 235-243 ◽  
Author(s):  
Donghua Liu ◽  
Wusheng Jiang ◽  
Shuming Tong ◽  
Lin Zhai

Effects of Mg2+ and Co2+ on cell division and the nucleolar cycle during mitosis in root tip cells of Allium cepa were studied. The concentrations used of magnesium sulphate and cobaltous nitrate were in the range of 10−7–10−1M. The results showed that both Mg and Co can, at higher concentration, have a toxic effect on cell division comprising c-mitosis and lagging chromosomes, anaphase bridges, and chromosome stickiness. Excessive Mg and Co can also induce some silver-stained particles similar to nucleoli, which are scattered around the chromosome or in the cytoplasm during metaphase and anaphase. The possible mechanism behind this phenomenon is briefly discussed.


2010 ◽  
Vol 73 (5) ◽  
pp. 949-954 ◽  
Author(s):  
W. Kwankua ◽  
S. Sengsai ◽  
C. Kuleung ◽  
N. Euawong

2007 ◽  
Vol 49 (4) ◽  
pp. 481-486 ◽  
Author(s):  
Jian-You Li ◽  
Ai-Liang Jiang ◽  
Wei Zhang

Genome ◽  
1988 ◽  
Vol 30 (1) ◽  
pp. 36-43 ◽  
Author(s):  
K. Kerby ◽  
J. Kuspira

To help elucidate the origin of the B genome in polyploid wheats, karyotypes of Triticum turgidum, Triticum monoccum, and all six purported B genome donors were compared. The analysis utilized a common cytological procedure that employed the most advanced equipment for the measurement of chromosome lengths at metaphase in root tip cells. A comparison of the karyotypes of T. turgidum and T. monococcum permitted the identification of B genome chromosomes of T. turgidum. These consist of two SAT pairs, one ST pair, three SM pairs, and one M pair of homologues. Comparisons of the chromosomes of the B genome of T. turgidum with the karyotypes of the six putative B genome donors showed that only the karyotype of Aegilops searsii was similar to the one deduced for the donor of the B genome in T. turgidum, suggesting that Ae. searsii is, therefore, the most likely donor of the B genome to the polyploid wheats. Support for this conclusion has been derived from geographic, DNA-hybridization, karyotype, morphological, and protein data reported since 1977. Reasons why the B genome donor has not been unequivocally identified are discussed.Key words: phylogeny, karyotypes, Triticum turgidum, Triticum monococcum, B genome, B genome donors.


Nature ◽  
1949 ◽  
Vol 164 (4178) ◽  
pp. 930-930 ◽  
Author(s):  
J. CHAYEN

1992 ◽  
Vol 103 (4) ◽  
pp. 989-998 ◽  
Author(s):  
E.P. Eleftheriou ◽  
B.A. Palevitz

The relationship between microfilaments (Mfs) and microtubules (Mts) in the organization of the preprophase band (PPB) was investigated in Allium root tip cells subjected to treatment with cytochalasin D (CD). Mts and Mfs were visualized by indirect immunofluorescence and various parameters such as PPB width were analyzed quantitatively. In control samples, the PPB first appears as a wide Mt band that progressively narrows to an average width of 4 micrometre in mid-prophase. Randomly oriented Mfs are present throughout the cytoplasm of most interphase control cells. Preprophase and prophase cells, however, contain cortical Mfs arranged parallel to the PPB. The Mfs initially occupy much of the cortex but in most cells they progressively become restricted to an area wider than the PPB. In the presence of CD, the PPB fails to narrow and remains at least two-fold wider than in control cells. PPB width expressed as a percentage of nuclear or cell length also increases compared to controls. Widening is concentration dependent, and the effect of 10 micromolar CD is near maximal only 15 min after application of the drug. This rapid response suggests that a rebroadening of already condensed PPBs takes place. After as little as 15 min in CD, Mfs are replaced by many small specks and rods. Dual localizations of both Mts and Mfs show that prophase cells contain broad PPBs without Mfs. The rapid disorganization of Mfs, by CD, therefore coincides with the rebroadening of PPBs. CD-treated cells in metaphase, anaphase and telophase contain larger actin aggregates at the poles, as previously reported. The results indicate that Mfs play an important role in the narrowing of the PPB, which in turn is essential for determination of the exact position of the plane of division. They also indicate that movement of intact Mts is important in PPB organization.


Sign in / Sign up

Export Citation Format

Share Document