The involvement of phospholipases C and D in the asymmetric division of subsidiary cell mother cells ofZea mays

2008 ◽  
Vol 65 (11) ◽  
pp. 863-875 ◽  
Author(s):  
Panagiotis Apostolakos ◽  
Emmanuel Panteris ◽  
Basil Galatis
Keyword(s):  
Asymmetric Division ◽  
Subsidiary Cell ◽  
Mother Cells

scholarly journals Slit signaling promotes the terminal asymmetric division of neural precursor cells in the Drosophila CNS

Development ◽  
2001 ◽  
Vol 128 (16) ◽  
pp. 3161-3168 ◽  
Author(s):  
Brijesh Mehta ◽  
Krishna Moorthi Bhat
Keyword(s):  
Signaling Pathway ◽  
Asymmetric Division ◽  
Precursor Cells ◽  
Neural Precursor Cells ◽  
Neural Precursor ◽  
Down Regulation ◽  
Over Expression ◽  
Symmetric Division ◽  
A Cell ◽  
Mother Cells

The bipotential Ganglion Mother Cells, or GMCs, in the DrosophilaCNS asymmetrically divide to generate two distinct post-mitotic neurons. Here,we show that the midline repellent Slit (Sli), via its receptor Roundabout(Robo), promotes the terminal asymmetric division of GMCs. In GMC-1 of the RP2/sib lineage, Slit promotes asymmetric division by down regulating two POU proteins, Nubbin and Mitimere. The down regulation of these proteins allows the asymmetric localization of Inscuteable, leading to the asymmetric division of GMC-1. Consistent with this, over-expression of these POU genes in a late GMC-1 causes mis-localization of Insc and symmetric division of GMC-1 to generate two RP2s. Similarly, increasing the dosage of the two POU genes insli mutant background enhances the penetrance of the RP2 lineage defects whereas reducing the dosage of the two genes reduces the penetrance of the phenotype. These results tie a cell-non-autonomous signaling pathway to the asymmetric division of precursor cells during neurogenesis.

scholarly journals Expression of Hey marks a subset of enteroendocrine cells in the Drosophila embryonic and larval midgut

2021 ◽  
Author(s):  
Emilia Skafida ◽  
Christos Delidakis ◽  
Maria Monastirioti
Keyword(s):  
Nervous System ◽  
Transcription Factor ◽  
Notch Signaling ◽  
Asymmetric Division ◽  
Enteroendocrine Cells ◽  
Larval Midgut ◽  
Mammalian Genomes ◽  
Low Levels ◽  
Newborn Neurons ◽  
Mother Cells

Hey is a conserved transcription factor of the bHLH-Orange family and it participates in the response to Notch signaling in certain tissues. Whereas three Hey paralogues exist in mammalian genomes, Drosophila possesses a single Hey gene. Fly Hey is expressed in the subset of newborn neurons that receive a Notch signal to differentiate them from their sibling cells after the asymmetric division of precursors called ganglion-mother-cells. We used a polyclonal anti-Hey serum and a GFP-tagged transgenic duplication of the Hey locus to examine its expression in tissues outside the nervous system in embryos and larvae. We detected robust Hey expression in the embryonic midgut primordium at the time of birth of enteroendocrine cells, identified by expression of Prospero. About half of the Pros-positive cells were also Hey positive at mid-embryogenesis. By the end of embryogenesis, most enteroendocrine cells had downregulated Hey expression, although it was still detectable at low levels after hatching. Low levels of Hey were also detected in subsets of the epithelial enterocytes at different times. Embryo enteroendocrine Hey expression was found to be Notch dependent. In late third-instar larvae, when few new enteroendocrine cells are born, novel Hey expression was detected in one cell of each sibling pair. In conclusion, Hey is strongly expressed in one of each pair of newly-born enteroendocrine cells. This is consistent with a hypothesis that embryonic enteroendocrine cells are born by an asymmetric division of a precursor, where Notch/Hey probably distinguish between the subtypes of these cells upon their differentiation.

Positional inconsistency between preprophase microtubule band and final cell plate arrangement during triangular subsidiary cell and atypical hair cell formation in two Triticum species

1984 ◽  
Vol 62 (2) ◽  
pp. 343-359 ◽  
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
C. Katsaros
Keyword(s):  
Hair Cell ◽  
Mitotic Spindle ◽  
Cell Plate ◽  
Subsidiary Cell ◽  
Transverse Wall ◽  
Cortical Zone ◽  
Preprophase Microtubule Band ◽  
Mutual Disposition ◽  
Cell Plate Arrangement ◽  
Mother Cells

On the leaf epidermis of two Triticum species examined, an intervening cell of a stomatal or a hair row often flanks on one side two guard cell mother cells (GMC's) and usually functions twice as a subsidiary cell mother cell (SMC). In many of these cells and rarely in SMC's corresponding to one GMC, a triangular subsidiary cell (SC) instead of a lens-shaped one is formed. Some of these SC's in median paradermal sections appear triangular in form, while in internal and (or) external ones they exhibit a lenslike shape. In all SMC's investigated in which a triangular SC was expected to be formed, the preprophase microtubule band (PMB) occupied the usual position adjacent to the inducing GMC, except for instances in which the transverse wall of the SMC intersected the lateral wall of the GMC or was opposite its transverse wall. Therefore, during triangular SC formation a limited portion of the junction region of the cell plate with the parent walls is predicted by the PMB. In such cases the premitotic polarizing process in the SMC's and consequently the mutual disposition between the PMB and the mitotic spindle is disturbed. The PMB's of the hair cell mother cells (HMC's) are not so densely grouped as those of the SMC's, sometimes occupying an extensive portion along the walls. They were localized at the expected positions at the polar end of the cells. Only in few instances were atypical PMB's organized. However, the cell plate separating the hair cells (HC's) sometimes diverges and fuses with the parent walls at unpredictable positions far from the PMB cortical zone, except for a small part of it adjacent to one longitudinal anticlinal wall of the HMC. In addition, the preprophase–prophase nucleus often occupied an eccentric position in relation to the PMB or more rarely was situated outside it. Sometimes it exhibited a particular orientation. Moreover, mitotic spindles inclined in relation to the PMB plane were frequently observed. The above phenomena seem to be the result of the interference of a transverse polarizing stimulus with an axial one or of the establishment of an aberrant polarity in the HMC's for unknown reasons. The observations suggest that the spatial inconsistency between PMB and final cell plate arrangement in the cells investigated is an exception to the rule, caused by the disturbance of the mutual disposition and orientation between PMB cortical zone and mitotic spindle; these phenomena follow the disorder of the polarizing process of the cells. The PMB cortical zone seems to be effective only when the cell plate edges reach a critical distance from it.

Microtubule Orientation During Stomatal Differentiation in Grasses

1989 ◽  
Vol 92 (4) ◽  
pp. 581-594
Author(s):  
SOON-OK CHO ◽  
SUSAN M. WICK
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Guard Cell ◽  
Mother Cell ◽  
Early Stage ◽  
Preprophase Band ◽  
Subsidiary Cell ◽  
Stomatal Complex ◽  
Face View ◽  
Mother Cells

The changing orientation of microtubules (MTs) during formation of the stomatal complex in grasses was observed by immunofluorescence microscopy, beginning with the asymmetrical division of the cell that gives rise to the guard cell mother cell, i.e. the guard cell grandmother cell. The asymmetrically placed preprophase band (PPB) of guard cell grandmother cells and hair cell mother cells is always laid down parallel to the distal end wall even when this wall is oblique to the long axis of the cell. The first step in formation of the PPB of a subsidiary cell mother cell appears to be establishment of an incomplete band of MTs. Whereas the mature PPB forms a curved line in a face view of a subsidiary cell mother cell, in this early stage MTs form fan-shaped arrays that focus on two points along the edge of the subsidiary cell mother cell. Replacement of the transversely oriented interphase microtubule band of the guard cell mother cell with the longitudinally oriented PPB involves several distinctive stages: (1) appearance of MTs directed toward the centre of the periclinal surface along the entire length of the lateral walls. (2) Appearance of another set of MTs along the entire width of both end walls, likewise focused toward the centre of the periclinal surface. Together these two groups of MTs form a cross with broadened tips in face view of the leaf. (3) Disappearance of the first set of MTs, and formation of an increasingly narrow band from the latter at the site of future cytokinesis. Although the anaphase spindles of guard cell grandmother cells, hair cell mother cells and guard cell mother cells are usually diagonally oriented relative to the site occupied previously by the PPB, the line connecting the centres of the spindle poles that are established at prophase is perpendicular to the persisting PPBs. Unlike the situation in certain other hair cells, MTs in leaf hair cells are transversely oriented even when the cells are highly elongated.

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