scholarly journals Sensory mother cell division is specifically affected in a Cyclin-A mutant of Drosophila melanogaster.

1992 ◽  
Vol 11 (8) ◽  
pp. 2935-2939 ◽  
Author(s):  
R. Ueda ◽  
S. Togashi ◽  
M. Takahisa ◽  
S. Tsurumura ◽  
M. Mikuni ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Mother Cell ◽  
Cyclin A

Cell grouping and primary wall generations in the cambial zone, xylem, and phloem in Pinus

1968 ◽  
Vol 16 (2) ◽  
pp. 177 ◽  
Author(s):  
A Mahmood
Keyword(s):  
Cell Division ◽  
Mother Cell ◽  
Secondary Wall ◽  
Radial Direction ◽  
Cell Plate ◽  
Tangential Direction ◽  
Primary Wall ◽  
Photographic Evidence ◽  
Secondary Wall Deposition ◽  
Cambial Zone

The use of the term cambium, or equivalent terms, in modern literature is discussed. The term cambial zone adopted in this paper includes the cambial initial and the dividing and enlarging cells. The tissue mother cell produced at each division of the initial produces a group of four cells in xylem or two cells in phloem. Theoretical constructs have been made for xylem and phloem production by associating the concepts that xylem and phloem are produced in alternate series of initial divisions and that a new primary wall is deposited around each daughter protoplast at each cell division. Correlations are derived from the theoretical constructs for the thickness of primary wall layers lying in the tangential direction and of those lying in the radial direction at progressive histological levels. Deductions from theoretical constructs are made when the initial is producing xylem, when it changes its polarity from xylem to phloem production, and when the reverse change occurs. Most of the theoretical deductions are supported by photographic evidence. The chief point of this study is the demonstration of generations (multiplicity) of primary parental walls. The term intercellular material proposed in this paper includes the cell plate plus any remnants of ancestral primary walls between the current primary walls surrounding the adjacent protoplasts. This term is still applicable to cells where secondary wall deposition is taking place or has been completed.

scholarly journals Functional monopolar spindles caused by mutation in mgr, a cell division gene of Drosophila melanogaster

1988 ◽  
Vol 89 (1) ◽  
pp. 39-47 ◽  
Author(s):  
C. Gonzalez ◽  
J. Casal ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Genetic Analysis ◽  
Normal Chromosome ◽  
Phenotypic Traits ◽  
Polyploid Cells ◽  
A Cell

Mutation in the gene merry-go-round (mgr) of Drosophila causes a variety of phenotypic traits in somatic and germinal tissues, such as polyploid cells, metaphasic arrest, postmeiotic cysts with 16 nuclei, and spermatids with four times the normal chromosome content. The most characteristic phenotype is the appearance of mitotic and meiotic figures where all chromosomes are arranged in a circle. Treatment with anti-mitotic drugs and the phenotype of double mutants mgr asp (asp being a mutation altering the spindle) show that these circular figures need a functional spindle for their formation. These abnormal figures are caused by monopolar spindles similar to those observed after different treatments in several organisms. All mutant traits indicate that mgr performs a function necessary for the correct behaviour of centrosomes, thus opening this organelle to genetic analysis.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

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.

scholarly journals The Vaccinia-related Kinases Phosphorylate the N′ Terminus of BAF, Regulating Its Interaction with DNA and Its Retention in the Nucleus

2006 ◽  
Vol 17 (5) ◽  
pp. 2451-2464 ◽  
Author(s):  
R. Jeremy Nichols ◽  
Matthew S. Wiebe ◽  
Paula Traktman
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Nuclear Envelope ◽  
Temperature Sensitivity ◽  
Nuclear Membrane ◽  
Essential Role ◽  
Nuclear Architecture ◽  
Nuclear Chromatin ◽  
N Terminus ◽  
Protein Barrier

The vaccinia-related kinases (VRKs) comprise a branch of the casein kinase family whose members are characterized by homology to the vaccinia virus B1 kinase. The VRK orthologues encoded by Caenorhabditis elegans and Drosophila melanogaster play an essential role in cell division; however, substrates that mediate this role have yet to be elucidated. VRK1 can complement the temperature sensitivity of a vaccinia B1 mutant, implying that VRK1 and B1 have overlapping substrate specificity. Herein, we demonstrate that B1, VRK1, and VRK2 efficiently phosphorylate the extreme N′ terminus of the BAF protein (Barrier to Autointegration Factor). BAF binds to both DNA and LEM domain-containing proteins of the inner nuclear membrane; in lower eukaryotes, BAF has been shown to play an important role during the reassembly of the nuclear envelope at the end of mitosis. We demonstrate that phosphorylation of ser4 and/or thr2/thr3 abrogates the interaction of BAF with DNA and reduces its interaction with the LEM domain. Coexpression of VRK1 and GFP-BAF greatly diminishes the association of BAF with the nuclear chromatin/matrix and leads to its dispersal throughout the cell. Cumulatively, our data suggest that the VRKs may modulate the association of BAF with nuclear components and hence play a role in maintaining appropriate nuclear architecture.

scholarly journals Cell Division by Longitudinal Scission in the Insect EndosymbiontSpiroplasma poulsonii

mBio ◽  
2016 ◽  
Vol 7 (4) ◽  
Author(s):  
Elodie Ramond ◽  
Catherine Maclachlan ◽  
Stéphanie Clerc-Rosset ◽  
Graham W. Knott ◽  
Bruno Lemaitre
Keyword(s):  
Electron Microscopy ◽  
Drosophila Melanogaster ◽  
Cell Division ◽  
Longitudinal Mode ◽  
Fruit Fly ◽  
Endosymbiotic Bacterium ◽  
Infected Female ◽  
Immunogold Staining ◽  
Ftsz Protein ◽  
Mode Of Life

ABSTRACTSpiroplasmabacteria are highly motile bacteria with no cell wall and a helical morphology. This clade includes many vertically transmitted insect endosymbionts, includingSpiroplasma poulsonii, a natural endosymbiont ofDrosophila melanogaster.S. poulsoniibacteria are mainly found in the hemolymph of infected female flies and exhibit efficient vertical transmission from mother to offspring. As is the case for many facultative endosymbionts,S. poulsoniican manipulate the reproduction of its host; in particular,S. poulsoniiinduces male killing inDrosophila melanogaster. Here, we analyze the morphology ofS. poulsoniiobtained from the hemolymph of infectedDrosophila. This endosymbiont was not only found as long helical filaments, as previously described, but was also found in a Y-shaped form. The use of electron microscopy, immunogold staining of the FtsZ protein, and antibiotic treatment unambiguously linked the Y shape ofS. poulsoniito cell division. Observation of the Y shape in anotherSpiroplasma,S. citri, and anecdotic observations from the literature suggest that cell division by longitudinal scission might be prevalent in theSpiroplasmaclade. Our study is the first to report the Y-shape mode of cell division in an endosymbiotic bacterium and addsSpiroplasmato the so far limited group of bacteria known to utilize this cell division mode.IMPORTANCEMost bacteria rely on binary fission, which involves elongation of the bacteria and DNA replication, followed by splitting into two parts. Examples of bacteria with a Y-shape longitudinal scission remain scarce. Here, we report thatSpiroplasma poulsonii, an endosymbiotic bacterium living inside the fruit flyDrosophila melanogaster, divide with the longitudinal mode of cell division. Observations of the Y shape in anotherSpiroplasma,S. citri, suggest that this mode of scission might be prevalent in theSpiroplasmaclade.Spiroplasmabacteria are wall-less bacteria with a distinctive helical shape, and these bacteria are always associated with arthropods, notably insects. Our study raises the hypothesis that this mode of cell division by longitudinal scission could be linked to the symbiotic mode of life of these bacteria.

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