Holocentric chromosome behaviour inCuscuta (Cuscutaceae)

1994 ◽  
Vol 191 (1-2) ◽  
pp. 105-109 ◽  
Author(s):  
Batia Pazy ◽  
Uzi Plitmann
Keyword(s):  
Chromosome Behaviour ◽  
Holocentric Chromosome

MEIOSIS IN THE GRASSHOPPER. II. THE PRELEPTOTENE SPIRAL STAGE DURING OOGENESIS AND SPERMATOGENESIS IN MELANOPLUS FEMUR-RUBRUM

1972 ◽  
Vol 14 (2) ◽  
pp. 397-401 ◽  
Author(s):  
Kathleen Church
Keyword(s):  
Dna Synthesis ◽  
Crossing Over ◽  
Chromosome Behaviour ◽  
Homologous Chromosomes ◽  
Diploid Complement

Chromosome behaviour occurring from premeiotic DNA synthesis to leptotene of meiosis is described for both males (spermatogenesis) and females (oogenesis) in the grasshopper Melanoplus femur-rubrum. These events include a period of chromosome spiralization and contraction following premeiotic DNA synthesis and prior to leptotene. The diploid complement of chromosomes becomes visible in both sexes. No pairing between homologous chromosomes or chiasmata are observed in either sex. The results suggest that synapsis and crossing over must occur following preleptotene spiralization during spermatogenesis and oogenesis in this grasshopper.

scholarly journals Mechanisms of chromosome behaviour during mitosis

2010 ◽  
Vol 11 (2) ◽  
pp. 91-102 ◽  
Author(s):  
Claire E. Walczak ◽  
Shang Cai ◽  
Alexey Khodjakov
Keyword(s):  
Chromosome Behaviour

Persisting demibivalents: a unique meiotic behaviour in Cuscuta babylonica Choisy

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Batia Pazy ◽  
Uzi Plitmann
Keyword(s):  
Key Words ◽  
Chromosome Segregation ◽  
Meiotic Behaviour ◽  
Chromosome Behaviour ◽  
Chromosome Movement ◽  
Pollen Mother Cells ◽  
Key Words Meiosis ◽  
Mother Cells ◽  
Telomeric Association

Idiosyncratic chromosome behaviour during meiosis was found in pollen mother cells of Cuscuta babylonica Choisy, a thread-like holoparasitic herb. Its main features are among the following: (i) telomeric association between homologues through most stages of the process, which leads to persisting chromatid bivalents (= "demibivalents"); (ii) uncommon chromosome segregation in first and second anaphase; and (iii) prolonged intensified heterochromatinization. Although "regular" in its own way, this process leads to the formation of unviable products. Its further investigation might contribute to our understanding of the role of the spindle and chromosome movement in the ordinary process of meiosis. Key words: meiosis (abnormal), persisting demibivalents, Cuscuta babylonica.

Morphology and behaviour of dinoflagellate chromosomes during the cell cycle and mitosis

2000 ◽  
Vol 113 (7) ◽  
pp. 1231-1239 ◽  
Author(s):  
Y. Bhaud ◽  
D. Guillebault ◽  
J. Lennon ◽  
H. Defacque ◽  
M.O. Soyer-Gobillard ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Confocal Microscopy ◽  
Nuclear Envelope ◽  
Chromosome Segregation ◽  
Morphological Changes ◽  
S Phase ◽  
Chromosome Behaviour ◽  
Double Number ◽  
Do So

The morphology and behaviour of the chromosomes of dinoflagellates during the cell cycle appear to be unique among eukaryotes. We used synchronized and aphidicolin-blocked cultures of the dinoflagellate Crypthecodinium cohnii to describe the successive morphological changes that chromosomes undergo during the cell cycle. The chromosomes in early G(1) phase appeared to be loosely condensed with numerous structures protruding toward the nucleoplasm. They condensed in late G(1), before unwinding in S phase. The chromosomes in cells in G(2) phase were tightly condensed and had a double number of arches, as visualised by electron microscopy. During prophase, chromosomes elongated and split longitudinally, into characteristic V or Y shapes. We also used confocal microscopy to show a metaphase-like alignment of the chromosomes, which has never been described in dinoflagellates. The metaphase-like nucleus appeared flattened and enlarged, and continued to do so into anaphase. Chromosome segregation occurred via binding to the nuclear envelope surrounding the cytoplasmic channels and microtubule bundles. Our findings are summarized in a model of chromosome behaviour during the cell cycle.

Dosage dependence of maternal contribution to somatic cell division in Drosophila melanogaster

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
M. Carmena ◽  
C. Gonzalez ◽  
J. Casal ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Somatic Cell ◽  
Early Development ◽  
Normal Cell ◽  
Chromosome Behaviour ◽  
Wild Type ◽  
Maternal Contribution ◽  
Different Doses ◽  
Chromosome Nondisjunction

Most mitotic mutants in Drosophila do not lead to lethality in early development despite the highly abnormal chromosome behaviour that they elicit. This has been explained as being the effect of maternally provided wild-type products. We have tested this hypothesis by studying cuticular clones derived from cells in which there has been loss of a marked Y chromosome due to chromosome nondisjunction in individuals homozygous for the mutation abnormal spindle who are progeny of heterozygous mothers. We have found that the size and frequency of these clones are higher than in control flies. Furthermore, by analysing flies whose female parents have different doses of the asp+ gene, we have found that there is a correlation between the amount of maternally contributed asp+ product and the frequency and size of cuticular clones. We have also estimated the time in development when the first mitotic mistakes take place, i.e. the time when maternal products are no longer sufficient to carry out normal cell division.

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