The organization of microtubules in guard cell mother cells of Zea mays

1982 ◽  
Vol 60 (7) ◽  
pp. 1148-1166 ◽  
Author(s):  
B. Galatis
Keyword(s):  
Zea Mays ◽  
Nuclear Envelope ◽  
Guard Cell ◽  
Cortical Microtubule ◽  
Colchicine Treatment ◽  
Early Prophase ◽  
Cortical Regions ◽  
Periclinal Walls ◽  
Mother Cells ◽  
Dictyosome Vesicles

The cortical interphase microtubules of the guard cell mother cells (GMCs) of Zea mays form a well-grouped band (interphase microtubule band, IMB) lining the midregion of the lateral and periclinal walls, which are the only expanding walls during interphase. In advanced interphase GMCs, another population of microtubules emerge from the cortical cytoplasm of the midregion of the periclinal walls, entering deep into the cytoplasm. Elongated proplastids converge on the above cortical regions, possibly aligned by the microtubules with which they are associated.The IMB depolymerizes prior to mitosis and a preprophase microtubule band (PMB) is organized adjacent to the proximal, distal, and periclinal walls. In transverse sections the preprophase – early prophase nucleus appears slightly elliptical or spindle-shaped, sometimes exhibiting acute angular profiles at its poles. Extranuclear microtubules closely juxtaposed with the nuclear envelope converge on the "poles" of the nucleus, close to the regions of the PMB adjacent to the periclinal walls. The observations suggest a local interplay between the PMB and (or) the PMB cytoplasmic site on the one hand and the nuclear envelope and (or) the extranuclear microtubules on the other.The microtubules of both bands lining the periclinal walls and the sites of their junctions with the anticlinal ones are more closely grouped than those running along the anticlinal walls, and they exhibit intimate associations with numerous dictyosome vesicles. This preferential gathering of dictyosome vesicles, among others, possibly manifests a mechanism promoting the thickening of the expanding regions of the above walls.The inhibition of the symmetrical divisions of the GMCs by a continuous colchicine treatment leads to the formation of epidermal idioblasts possessing some of the characteristidcs of the guard cells. Furthermore, in the absence of microtubules, local wall thickenings are deposited in the middle of the periclinal walls and at their junctions with the anticlinal ones.From the observations it seems likely that guard cell differentiation commences in GMC, and that the cortical cytoplasm and (or) the plasmalemma of the midregion and the edges of the periclinal walls of the GMC possess some factor(s) favouring their preferential thickening. Cortical microtubule organizing centres (MTOCs) appear to be localized in these regions and activated in a programmed fashion.

Studies on the formation of ‘floating’ guard cell mother cells in Anemia

1986 ◽  
Vol 80 (1) ◽  
pp. 29-55
Author(s):  
B. Galatis ◽  
P. Apostolakos ◽  
D. Palafoutas
Keyword(s):  
Guard Cell ◽  
Intercellular Space ◽  
Cortical Microtubule ◽  
Cell Plate ◽  
Cell Polarization ◽  
Periclinal Wall ◽  
Wall Area ◽  
Cortical Zone ◽  
Neighbouring Region ◽  
Mother Cells

The protodermal cells producing the ‘floating’ guard cell mother cells (GMCs) in three Anemia species undergo an extraordinary polarization and an unexpected shaping. During interphase an intercellular space is initiated at the internal proximal end of the cell, while the polar region bulges outwards. At this stage a microtubule girdle traverses the cortical cytoplasm underneath the rims of the external periclinal wall curvature. In addition, another system of microtubules converges on a cortical site adjoining the wall delimiting the intercellular space and, or, the neighbouring region of the internal periclinal wall (internal polar cortical site, IPCS). Vacuoles are found in all regions of the cell except for that between the centrally located nucleus and the intercellular space. As the cell approaches mitosis, the growing vacuolar system retreats from the cytoplasmic region below the external periclinal wall curvature. In most cells the polarized cytoplasm forms an inclined truncated cone, the bases of which abut on the external periclinal wall curvature and the wall lining the IPCS. The organization of the cortical microtubule cytoskeleton does not change significantly during preprophase-prophase. A preprophase microtubule band (PMB) is localized in the cortex lining the rims of the external periclinal wall curvature, while some microtubules traverse the IPCS and the cytoplasm adjacent to the neighbouring wall regions. The mitotic spindle axis is diagonal, while the cell plate separating the GMCs exhibits an unusual mode of growth. It gradually encircles the proximal daughter nucleus, becoming funnel-shaped. One of its periclinal edges fuses with the external periclinal wall area lined by the PMB cortical zone and the other with the internal periclinal wall area adjoining the IPCS. The latter region seems to behave like the PMB cortical zone. The results show that the morphogenetic mechanism underlying the formation of the conical GMCs includes a series of highly integrated processes, initiated or carried out during cell polarization.

Molecular cytogenetic analysis of wheat-alien hybrids and derivatives

2002 ◽  
Vol 50 (3) ◽  
pp. 303-311 ◽  
Author(s):  
M. Molnár-Láng ◽  
G Linc ◽  
E. D. Nagy ◽  
Keyword(s):  
Ssr Markers ◽  
Molecular Genetic ◽  
Colchicine Treatment ◽  
Translocation Chromosome ◽  
Chromosome Polymorphism ◽  
Translocation Breakpoints ◽  
Mother Cells ◽  
High Degree

New wheat × barley, wheat × Aegilops biuncialis and wheat × rye hybrids were produced with the aim of alien gene transfer from these species into wheat. Amphiploids were produced with the help of colchicine treatment from the last two combinations. The new wheat × barley hybrids were multiplied in tissue culture because of the high degree of sterility and then pollinated with wheat to obtain backcross progenies. Wheat-barley chromosome pairing was detected using genomic in situ hybridization (GISH) in two combinations (Mv9 kr1 × Igri, Asakazekomugi × Manas). In vitro conditions caused an increase in chromosome arm association frequency in both combinations and in fertility in some regenerants. Five wheat-barley translocations were produced in a wheat background and characterized through the combination of cytogenetic and molecular genetic approaches (GISH, FISH and SSR markers). The following translocations were identified: 2DS.2DL-1HS, 3HS.3BL, 6BS.6BL-4HL, 4D-5HS and 7DL.7DS-5HS. Physical mapping of the SSR markers on chromosomes 1H and 5H was carried out using the intragenomic and interspecific translocation breakpoints and the centromere as physical landmarks.  Disomic wheat-Aegilops biuncialis additions were produced after backcrossing the wheat-Ae. biuncialis amphiploids. Fluorescence in situ hybridization (FISH) was carried out using two repetitive DNA clones (pSc119.2 and pAs1) on Ae. biuncialis and its two diploid progenitor species to detect chromosome polymorphism. The 7M and 3M disomic chromosome additions were selected and five more lines still need to be characterized.  The octoploid triticale (Mv9 kr1 × Lovászpatonai) produced in Martonvásár was crossed with a 1RS.1BL wheat cultivar Matador. GISH analysis detected pairing between the 1RS arm of the translocation chromosome and that of Lovászpatonai rye in 32 % of the pollen mother cells, making it possible to select recombinants from this combination. The new recombinants between the 1RS of Petkus and the 1RS of Lovászpatonai rye cultivars are being analysed with the help of microsatellite markers.

Sperm nuclear envelope: breakdown of intrinsic envelope and de novo formation in hamster oocytes or eggs

Zygote ◽  
1997 ◽  
Vol 5 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Noriko Usui ◽  
Atsuo Ogura ◽  
Yasuyuki Kimura ◽  
Ryuzo Yanagimachi
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
De Novo ◽  
Germinal Vesicle ◽  
Mature Oocyte ◽  
Sperm Nucleus ◽  
Sperm Chromatin ◽  
Early Prophase ◽  
Nuclear Envelope Breakdown ◽  
M Phase

SummaryDuring fertilisation of a fully mature oocyte, the sperm intrinsic nuclear envelope (SINE) disappears soon after sperm-oocyte fusion. A new nuclear envelope appears around the decondensed sperm chromatin when the oocyte reaches telophase II. Whether the SINE persists or rapidly disappears after sperm entery into immature oocytes or fertilised eggs has been controversial. Nuclear envelopes have been demonstrated around the sperm chromatin, which cannot be decondensed within the ooplasm of these oocytes or eggs, but whether these envelopes are persisting SINEs or newly formed envelopes has been apoint of dispute. To resolve this issue, the fate of the germinal vesicle stage(GV oocytes) or fertilised eggs at the pronuclear stage(PN eggs). The SINEs disappeared quikly within these oocytes or eggs, like those within maturing or mature oocytes, suggesting that the envelops around the sperm chromatin must be newly formed after SINE breakdown. To obtain further evidence, a detergent-treated, SINE-free sperm nucleus was injected into a PN egg. A new envelope appeared around the still-condensed or partially decondensed sperm chromatin within 3h after injection. Thus, disassembly of the SINE within ooplasm, unlike that of nuclear envelopes of other cells at prophase, is independent of the cell cycle stage of the oocyte or egg, whereas the ability of the ooplasm to assemble the new envelope is restricted to certain periods of the cycle. i.e. early prophase and telophase during meiosis and interphase, periods when active M-phase Promoting factor (MPF) is absent from the ooplasm.

Location of the HIV-1 Rev protein during mitosis: inactivation of the nuclear export signal alters the pathway for postmitotic reentry into nucleoli

1996 ◽  
Vol 109 (9) ◽  
pp. 2239-2251 ◽  
Author(s):  
M. Dundr ◽  
G.H. Leno ◽  
N. Lewis ◽  
D. Rekosh ◽  
M.L. Hammarskjoid ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Export ◽  
Nuclear Export Signal ◽  
Nucleolar Protein ◽  
Early Prophase ◽  
Nucleolar Proteins ◽  
Late Telophase ◽  
Export Signal ◽  
Hiv 1 ◽  
Rev Protein

The HIV-1 Rev protein localizes predominantly to the nucleolus of HIV-1-infected or Rev-expressing cells. The subcellular location of Rev during mitotic nucleolar disintegration was examined at various stages of mitosis in synchronized Rev-expressing CMT3 cells. During early prophase Rev was predominantly located in disintegrating nucleoli and began to accumulate at the peripheral regions of chromosomes in late prophase, eventually distributing uniformly on all chromosomes in prometaphase. In anaphase Rev remained associated with the perichromosomal regions, but significant amounts of Rev were also seen in numerous nucleolus-derived foci. The movement of Rev from disintegrating nucleoli to perichromosomal regions and foci was similar to that of nonribosomal nucleolar proteins, including fibrillarin, nucleolin, protein B23 and p52 of the granular component. During telophase Rev remained associated with perichromosomal regions and mitotic foci until the nuclear envelope started to reform. When nuclear envelope formation was complete in late telophase, nonribosomal nucleolar proteins were present in prenucleolar bodies (PNBs) which were eventually incorporated into nucleoli; at the same time, Rev was excluded from nuclei. In contrast, a trans-dominant negative Rev protein containing an inactive nuclear export signal reentered nuclei by the nonribosomal nucleolar protein pathway in late telophase, associating with PNBs and reformed nucleoli. Rev protein reentry into postmitotic nuclei was delayed until early G1 phase, but before the arrival of ribosomal protein S6. Thus, Rev behaves like a nonribosomal nucleolar protein through mitosis until early telophase; however, its nuclear reentry seems to require reestablishment of both a nuclear import system and active nucleoli.

Nucleolus-associated telomere clustering and pairing precede meiotic chromosome synapsis in Arabidopsis thaliana

2001 ◽  
Vol 114 (23) ◽  
pp. 4207-4217 ◽  
Author(s):  
Susan J. Armstrong ◽  
F. Christopher H. Franklin ◽  
Gareth H. Jones
Keyword(s):  
Arabidopsis Thaliana ◽  
Meiotic Chromosome ◽  
In Situ Hybridisation ◽  
Embryo Sac ◽  
Early Prophase ◽  
Homologous Chromosomes ◽  
Chromosome Synapsis ◽  
Mother Cells ◽  
Telomere Signal

The intranuclear arrangements of centromeres and telomeres during meiotic interphase and early prophase I of meiosis in Arabidopsis thaliana were analysed by fluorescent in situ hybridisation to spread pollen mother cells and embryo-sac mother cells. Meiocyte identification, staging and progression were established by spreading and sectioning techniques, including various staining procedures and bromodeoxyuridine labeling of replicating DNA. Centromere regions of Arabidopsis are unpaired, widely dispersed and peripherally located in nuclei during meiotic interphase, and they remain unpaired and unassociated throughout leptotene. Eventually they associate pairwise during zygotene, as part of the nucleus-wide synapsis of homologous chromosomes. Telomeres, by contrast, show a persistent association with the nucleolus throughout meiotic interphase. Variation in telomere signal number indicates that telomeres undergo pairing during this interval, preceding the onset of general chromosome synapsis. During leptotene the paired telomeres lose their association with the nucleolus and become widely dispersed. As the chromosomes synapse during zygotene, the telomeres reveal a loose clustering within one hemisphere, which may represent a degenerate or relic bouquet configuration. We propose that in Arabidopsis the classical leptotene/zygotene bouquet is absent and is replaced functionally by nucleolus-associated telomere clustering.

On the differential divisions and preprophase microtubule bands involved in the development of stomata of Vigna sinensis L

1979 ◽  
Vol 37 (1) ◽  
pp. 11-37
Author(s):  
B. Galatis ◽  
K. Mitrakos
Keyword(s):  
Cell Polarity ◽  
Cell Plate ◽  
Equatorial Position ◽  
Anticlinal Wall ◽  
Vigna Sinensis ◽  
Daughter Cells ◽  
Preprophase Microtubule Band ◽  
Dicotyledonous Plants ◽  
Mother Cells ◽  
Dictyosome Vesicles

The manifestation of premitotic cell polarity and the resultant structural asymmetry of the differential divisions participating in the development of stomata of Vigna sinensis vary considerably. However, two morphologically distinct types of differential division were distinguished: (a) ‘asymmetrical differential divisions’, in which the premitotic polarization of the cell, the eccentric position of the nucleus during division and the differences in size and organization of the daughter cells are obvious; and (b) differential divisions in which the above features are inconspicuous or almost absent. The former occur in the ordinary protodermal cells, the latter in some meristemoids. The organization of a sharply demarcated preprophase microtubule band (PMB) precedes, all differential and non-differential divisions. In the first type of differential division the PMB is formed eccentrically, while in the second it may display either an approximately symmetrical or a clearly asymmetrical disposition, always indicating with surprising accuracy the sites where the succeeding cell plate will join the parent walls. The PMB foreshadowing the highly curved cell plates in meristemoids I of the mesoperigenous process, as well as in meristemoids I and II of the mesogenous one, are apposed only on one anticlinal wall and therefore do not encircle the nucleus or traverse the cell. In the symmetrical divisions of guard cell mother cells (GMC), as well as in those of protodermal cells, the PMB runs right round the internal plasmalemma surface in an equatorial position, coinciding with that of the future cell plate. In the former cells the wall abutting the cortical cytoplasm traversed by the band becomes locally thickened. The variability in the pattern of the microtubules of the band along the walls of the GMC is directly mirrored in the pattern of the thickening. It seems that in GMC the PMB mediates a directed exocytosis of dictyosome vesicles. In contrast to what is now generally accepted in dicotyledonous plants, each meristemoid I of both the mesogenous and mesoperigenous stomata in Vigna sinensis leaves does not inhibit but induces the formation of other meristemoids close to it.

scholarly journals Identification of a Golgi-associated protein that undergoes mitosis dependent phosphorylation and relocation.

1990 ◽  
Vol 110 (5) ◽  
pp. 1513-1523 ◽  
Author(s):  
I McMorrow ◽  
W E Souter ◽  
G Plopper ◽  
B Burke
Keyword(s):  
Monoclonal Antibody ◽  
Nuclear Envelope ◽  
Immunofluorescence Microscopy ◽  
Nuclear Lamina ◽  
Early Prophase ◽  
Perinuclear Region ◽  
Nuclear Envelope Breakdown ◽  
Peripheral Membrane Protein ◽  
Double Label ◽  
Late Telophase

By means of a monoclonal antibody (BH3), we have identified a 57-kD protein (p57) that in interphase is restricted largely to the perinuclear region of the cell. Double label immunofluorescence microscopy suggests localization of p57 to the Golgi complex and associated membranous structures. Protease protection experiments and chemical extractability indicate that p57 is a peripheral membrane protein exposed to the cytoplasm. p57 displays unique behavior during mitosis. At the end of G2 or in early prophase, p57 leaves the perinuclear region and accumulates very rapidly within the nucleus, at a time when the nuclear envelope is still intact and before nuclear lamina disassembly. This relocation of p57 coincides with its hyperphosphorylation on serine and threonine residues. After nuclear envelope breakdown p57 becomes uniformly distributed throughout the mitotic cytoplasm until in late telophase when it returns to its perinuclear location and is once again excluded from the nucleus. The behavior of p57 during mitosis suggests that it may play a role in the cellular reorganization evident during mitotic prophase.

Studies on the development of the air pores and air chambers of Marchanda paleacea. II. Ultrastructure of the initial aperture formation with particular reference to cortical microtubule organizing centres

1985 ◽  
Vol 63 (4) ◽  
pp. 744-756 ◽  
Author(s):  
P. Apostolakos ◽  
B. Galatis
Keyword(s):  
Endoplasmic Reticulum ◽  
Continuous Function ◽  
Cortical Microtubule ◽  
Wall Thickening ◽  
Intercellular Spaces ◽  
Morphogenetic Process ◽  
Microtubule Organizing Centres ◽  
Periclinal Walls ◽  
Thickened Wall

The initiation of the intercellular spaces (ISs) of the initial apertures (IAs) follows the formation of surface cavities (SCs). The latter represent slight deepenings in the external periclinal walls of particular superficial thallus cells at the regions where their anticlinal walls meet one another. This event keeps pace with the deposition of wall pads at the wall junctions below the SC. Afterwards, the thickened wall areas are detached and thus the IS is initiated. By an inward development the IS reaches the subprotodermal layer. This is carried out by the coordination of three gradual processes: the inward spreading of the local wall thickening and the following detachment and expansion of the thickened regions. The findings favour the conclusion that the opening of the IS is the outcome of a highly controlled morphogenetic process. The interphase IA cells possess a well-organized cortical microtubule (MT) cytoskeleton, particularly at the area where the IS opens. In these regions, sets of anticlinal and periclinal MTs appear. During the SC stage the anticlinal MTs dominate, while during IS formation, the periclinal ones are most abundant. The above MTs, as well as other ones entering deeper in the cytoplasm, initially converge on the cortical cytoplasm adjacent to the SC and later on the region surrounding the lower part of the growing IS, where vesicles and endoplasmic reticulum are gathered. The observations suggest the continuous function of cortical MT organizing centres in the cytoplasm and (or) the adjoining plasmalemma, initially underneath the SC and later below the lower part of the growing IS, where local wall thickenings are deposited.

Sign in / Sign up

Export Citation Format

Share Document