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Mother Cells (mother + cell)
Kinds of Mother Cells Selected AbstractsThe involvement of phospholipases C and D in the asymmetric division of subsidiary cell mother cells of Zea maysCYTOSKELETON, Issue 11 2008Panagiotis Apostolakos Abstract In the present study, the involvement of phospholipase C and D (PLC and PLD) pathways in the asymmetric divisions that produce the stomatal complexes of Zea mays was investigated. In particular, the polar organization of microtubules (MTs) and actin filaments (AFs) and the process of asymmetric division were studied in subsidiary cell mother cells (SMCs) treated with PLC and PLD modulators. In SMCs treated with butanol-1 (but-1), which blocks phosphatidic acid (PA) production via PLDs, AF-patch formation laterally to the inducing guard cell mother cell (GMC) and the subsequent asymmetric division were inhibited. In these SMCs, cell division plane determination, as expressed by MT preprophase band (MT-PPB) formation, was not disturbed. Exogenously applied PA partially relieved the but-1 effects on SMCs. In contrast to SMCs, but-1 did not affect the symmetric GMC division. Inhibition of the PLC catalytic activity by neomycin or U73122 resulted in inhibition of asymmetric SMC division, while AF-patch and MT-PPB were organized as in control SMCs. These data show that the PLC and PLD signaling pathways are involved in the transduction and/or perception of the inductive stimulus that is emitted by the GMCs and induces the polar AF organization and asymmetric SMC division. In contrast, division plane determination in SMCs, as expressed by MT-PPB formation, does not depend on PLC and PLD signaling pathways. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Temporal and selective association of multiple sigma factors with RNA polymerase during sporulation in Bacillus subtilisGENES TO CELLS, Issue 2 2000Masaya Fujita Background During sporulation in Bacillus subtilis, an asymmetric division produces two cells, a forespore and mother cell, with which follow different developmental paths. The highly ordered programme of temporal and spatial gene activation during sporulation is governed by the principal RNA polymerase holoenzyme (E,A) and alternative holoenzyme forms containing the developmental sigma factors ,H, ,F, ,E, ,G and ,K, which appear successively during development. The control mechanism(s) of temporal and selective association of multiple sigma factors with core RNA polymerase is unclear. As a first step to addressing these issues, this report quantifies the amount of each subunit of RNA polymerase that is present in the sporangium during sporulation, and analyses in vitro the relative affinities of each sigma subunit for core RNA polymerase. Results Using quantitative immunoblot analysis, the amounts of E,A, E,H, E,E and E,K in relation to the total amount of RNA polymerase at appropriate time-points were found to be 15%, 1%, 6% and 2%, respectively. Therefore, the core RNA polymerase is predicted to be in excess. The level of core RNA polymerase and ,A remained constant during the transition from vegetative growth to sporulation, whereas the sporulation-specific sigma factors appeared successively, in the order ,H, ,E and ,K. Competition experiments between sigma factors in an in vitro transcription system revealed the dominance of ,A over ,H and ,E for open promoter complex formation. These results are inconsistent with the idea that late appearing sigma factors can displace earlier appearing sigmas from the core enzyme. Conclusions As the core RNA polymerase is in excess, the results suggest that successive sigma factors can bind to core RNA polymerase without having to displace earlier appearing sigma factors. Thus, the programme of gene expression during sporulation might not require mechanisms for the substitution of one sigma factor by another on the core RNA polymerase. [source] Sirt1's beneficial roles in neurodegenerative diseases , a chaperonin containing TCP-1 (CCT) connection?AGING CELL, Issue 5 2010Bin Qi Gan Summary Sir2/Sirt1 and its orthologues are known lifespan extension factors in several aging models from yeast to invertebrates. Sirt1 activation is also known to be beneficial and protective in both invertebrate and mammalian models of neurodegenerative disease. Sirt1's lifespan extension effect, as well as the beneficial outcome of its activation in models of aging-associated diseases, is often attributed to its ability to instill a gene expression profile that is pro-survival and anti-aging. A recent report from Nyström and colleagues showed that the yeast Sir2p affects the function of the polarisome in segregation and retrograde transport of damaged and aggregated proteins from the bud to the mother cell, thereby ensuring the generation of a ,rejuvenated' daughter cell. Interestingly, the role of Sir2p in this case involves deacetylation and activation of cytoplasmic chaperonin containing TCP-1 (CCT, or TriC), thereby enhancing actin folding and polymerization. In view of a previously documented role of CCT in modulating polyglutamine-containing protein aggregation and toxicity, we hypothesized that CCT deacetylation may also underlie Sirt1's beneficial effects in several neurodegenerative diseases precipitated by toxic aggregates. Other than alterations in gene expression profile, another major way whereby Sirt1 activation may counter neural aging could be to promote neuronal survival via prevention of toxic aggregate formation through CCT. [source] FtsK and SpoIIIE: the tale of the conserved tailsMOLECULAR MICROBIOLOGY, Issue 5 2007François-Xavier Barre Summary During Bacillus subtilis sporulation, the SpoIIIE DNA translocase moves a trapped chromosome across the sporulation septum into the forespore. The preferential assembly of SpoIIIE complexes in the mother cell provided the idea that SpoIIIE functioned as a DNA exporter, which ensured translocation orientation. In this issue of Molecular Microbiology, Becker and Pogliano reinvestigate the molecular mechanisms that orient the activity of SpoIIIE. Their findings indicate that SpoIIIE reads the polarity of DNA like its Escherichia coli homologue, FtsK. [source] Non-uniform assembly of the Bacillus anthracis exosporium and a bottle cap model for spore germination and outgrowthMOLECULAR MICROBIOLOGY, Issue 2 2007Christopher T. Steichen Summary Spores of Bacillus anthracis are enclosed by an exosporium composed of a basal layer and an external hair-like nap. The nap is formed by a collagen-like glycoprotein called BclA, while the basal layer contains many different proteins, one of which is a spore-specific alanine racemase (Alr). In this study, we employed fluorescence microscopy and a fluorescently labelled anti-Alr monoclonal antibody (mAb) to examine the distribution of Alr within the exosporium. Binding of the mAb occurred over approximately three-quarters of the exosporium but not in a cap-like region at one end of the spore, indicating the absence or inaccessibility of Alr in this region. We also determined that the cap-like region, or cap, corresponds to the first part of the exosporium assembled within the mother cell during sporulation and the only part of the exosporium assembled in a ,exsY mutant strain of B. anthracis. Our results provide the first direct evidence that exosporium assembly is a non-uniform process and suggest that exosporium formation is discontinuous. Finally, we demonstrated that during spore germination and outgrowth, the outgrowing cell always escapes from its exosporium shell by popping through the cap, suggesting that the cap is designed to facilitate the emergence of the outgrowing cell. [source] Serine proteases from two cell types target different components of a complex that governs regulated intramembrane proteolysis of pro-,K during Bacillus subtilis developmentMOLECULAR MICROBIOLOGY, Issue 3 2005Ruanbao Zhou Summary Upon starvation Bacillus subtilis undergoes a developmental process involving creation of two cell types, the mother cell and forespore. A signal in the form of a serine protease, SpoIVB, is secreted from the forespore and leads to regulated intramembrane proteolysis (RIP) of pro-,K, releasing active ,K into the mother cell. RIP of pro-,K is carried out by a membrane-embedded metalloprotease, SpoIVFB, which is inactive when bound by BofA and SpoIVFA. We have investigated the mechanism by which this complex is activated. By expressing components of the signalling pathway in Escherichia coli, we reconstructed complete inhibition of pro-,K RIP by BofA and SpoIVFA, and found that SpoIVB serine protease activity could partially restore RIP, apparently by targeting SpoIVFA. Pulse-chase experiments demonstrated that SpoIVFA synthesized early during B. subtilis sporulation is lost in a SpoIVB-dependent fashion, coincident with the onset of pro-,K RIP, supporting the idea that SpoIVB targets SpoIVFA to trigger RIP of pro-,K. Loss of BofA depended not only on SpoIVB, but also on CtpB, a serine protease secreted from the mother cell. CtpB appeared to cleave BofA near its C-terminus upon coexpression in E. coli, and purified CtpB degraded BofA. We propose that RIP of pro-,K involves a three-step proteolytic cascade in which SpoIVB first cleaves SpoIVFA, CtpB then cleaves BofA and finally SpoIVFB cleaves pro-,K. [source] Introgression of a gene for delayed pigment gland morphogenesis from Gossypium bickii into upland cottonPLANT BREEDING, Issue 6 2005S. J. Zhu Abstract The presence of gossypol and its derivatives above the WHO/FAO standards (0.02,0.04%) in cotton seed oil and meal limits its usage as food and feed. To the contrary, the presence of pigment glands filled with gossypol and its derivatives helps to protect cotton plants from phytophageous pests. Thus a desirable cultivar would have glandless seeds on a glanded plant. This paper describes results on the successful introgression of this trait from Gossypium bickii into cultivated upland cotton. Five different tri-specific hybrids (ABH1, ABH2, ABH3, ABH4 and ABH5) were obtained by crossing the amphidiploid F1 (G. arboreum × G. bickii) with different gland genotypes of G. hirsutum as male parent. The hybrids were highly sterile, and their chromosome configuration at meiosis metaphase 1 (M1) in pollen mother cell (PMC) was 2n = 52 = 41.04 I + 4.54 II + 0.57 III + 0.04 IV. All five hybrids were similar in morphological characters, except for the gland expression and gossypol contents. The hybrid (ABH3) derived from genotype Gl2Gl2gl3gl3 of upland cotton (a single gene dominant line) had completely introgressed the target trait of G. bickii. While ABH1 and ABH2, which derived from recessive (gl2gl2gl3gl3) or dominant (GlGl) glandless upland cotton genotypes, had glandless seeds too, but the density and size of the glands on the plant were reduced significantly. [source] Mum, this bud's for you: Where do you want it? roles for Cdc42 in controlling bud site selection in Saccharomyces cerevisiaeBIOESSAYS, Issue 9 2003W. James Nelson The generation of asymmetric cell shapes is a recurring theme in biology. In budding yeast, one form of cell asymmetry occurs for division and is generated by anisotropic growth of the mother cell to form a daughter cell bud. Previous genetic studies uncovered key roles for the small GTPase Cdc42 in organizing the actin cytoskeleton and vesicle delivery to the site of bud growth,1,2 but a recent paper has also raised questions about how control of Cdc42 activity is integrated into a proposed hierarchical regulatory pathway that specifies a unique site of bud formation.3 BioEssays 25:833,836, 2003. © 2003 Wiley Periodicals, Inc. [source] The involvement of phospholipases C and D in the asymmetric division of subsidiary cell mother cells of Zea maysCYTOSKELETON, Issue 11 2008Panagiotis Apostolakos Abstract In the present study, the involvement of phospholipase C and D (PLC and PLD) pathways in the asymmetric divisions that produce the stomatal complexes of Zea mays was investigated. In particular, the polar organization of microtubules (MTs) and actin filaments (AFs) and the process of asymmetric division were studied in subsidiary cell mother cells (SMCs) treated with PLC and PLD modulators. In SMCs treated with butanol-1 (but-1), which blocks phosphatidic acid (PA) production via PLDs, AF-patch formation laterally to the inducing guard cell mother cell (GMC) and the subsequent asymmetric division were inhibited. In these SMCs, cell division plane determination, as expressed by MT preprophase band (MT-PPB) formation, was not disturbed. Exogenously applied PA partially relieved the but-1 effects on SMCs. In contrast to SMCs, but-1 did not affect the symmetric GMC division. Inhibition of the PLC catalytic activity by neomycin or U73122 resulted in inhibition of asymmetric SMC division, while AF-patch and MT-PPB were organized as in control SMCs. These data show that the PLC and PLD signaling pathways are involved in the transduction and/or perception of the inductive stimulus that is emitted by the GMCs and induces the polar AF organization and asymmetric SMC division. In contrast, division plane determination in SMCs, as expressed by MT-PPB formation, does not depend on PLC and PLD signaling pathways. Cell Motil. Cytoskeleton 2008. © 2008 Wiley-Liss, Inc. [source] Microsporogenesis and meiotic behavior in nine species of the genus PinusJOURNAL OF SYSTEMATICS EVOLUTION, Issue 4 2009Hui-Sheng DENG Abstract The meiotic behavior of 10 taxa (nine species and one variety) of the genus Pinus was investigated using pollen mother cells (PMCs) to reveal the differentiation among karyotypes. Chromosome spreads were prepared by conventional squashing. The meiotic index and the average configuration were higher, whereas the frequency of aberrance (chromosomal bridges, fragments, or micronuclei) was lower, in all 10 taxa compared with other gymnosperms. The meiotic index, average configuration, and frequency of irregularity were found to be uniform among the species. It was shown that the genomes of the Pinus species investigated were highly stable, confirming results of previous mitotic analyses in this genus. However, slight differentiation of homologous chromosomes among genomes was revealed by analysis of meiotic configurations in Pinus nigra var. poiretiana. Quadrivalents were observed in 9.31% of PMCs in this species. This is the first time that quadrivalents have been observed in gymnosperms. [source] The red-ox status of a penicillin-binding protein is an on/off switch for spore peptidoglycan synthesis in Bacillus subtilisMOLECULAR MICROBIOLOGY, Issue 1 2010Patrick Eichenberger Summary Thiol-disulphide oxidoreductases catalyse the formation or breakage of disulphide bonds to control the red-ox status of a variety of proteins. Their activity is compartmentalized, as exemplified by the distinct roles these enzymes play in the cytoplasm and periplasm of Gram-negative bacteria. In this issue of Molecular Microbiology, an article from Lars Hederstedt and collaborators at Lund University sheds light on another member of this superfamily of proteins, the thioredoxin-like protein StoA from Bacillus subtilis. Interestingly, StoA function is required in yet another subcellular compartment: the intermembrane space that separates forespores from mother cells in endospore-forming bacteria. Specifically, this study demonstrates that the high-molecular-weight penicillin-binding protein SpoVD, which contains two exposed cysteine residues and whose extracellular domain is located in the intermembrane space, is a substrate of StoA. As formation of a disulphide bond most likely inactivates SpoVD activity, the converse breakage of that bond in a process catalysed by StoA appears to be the trigger that initiates peptidoglycan synthesis in sporulating cells. [source] The SUN41 and SUN42 genes are essential for cell separation in Candida albicansMOLECULAR MICROBIOLOGY, Issue 5 2007Arnaud Firon Summary Completion of the yeast cell cycle involves extensive remodelling of the cell wall upon separation of mother and daughter cells. We have studied two members of the ascomycete-specific SUN gene family in Candida albicans. Inactivation of SUN41 yields defects in cell separation and hyphal elongation while inactivation of SUN42 results in minor phenotypic alterations. Simultaneous inactivation of SUN41 and SUN42 is synthetically lethal due to lysis of mother cells after septation. Electronic microscopy reveals cell wall defects mainly localized in the region surrounding the septa. This phenotype is osmoremediable and the conditional double mutants show increased sensitivity to cell wall or cell membrane perturbing agents. The essential function shared by Sun41p and Sun42p is conserved among yeasts because UTH1, a Saccharomyces cerevisiae SUN gene, suppresses the lethality of SUN41 and SUN42 conditional mutants. Investigation of functional genomic data obtained in S. cerevisiae reveals links between members of the SUN gene family and the RAM pathway regulating cell wall-degrading enzymes specifically involved during cell separation. Thus, the main function of ascomycetous Sun proteins appears linked to cell wall remodelling, with a probable role in counter-balancing cell wall degradation to avoid cell lysis upon cell separation. [source] Expression of CP4 EPSPS in microspores and tapetum cells of cotton (Gossypium hirsutum) is critical for male reproductive development in response to late-stage glyphosate applicationsPLANT BIOTECHNOLOGY JOURNAL, Issue 5 2006Yun-Chia Sophia Chen Summary Plants expressing Agrobacterium sp. strain CP4 5-enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) are known to be resistant to glyphosate, a potent herbicide that inhibits the activity of the endogenous plant EPSPS. The RR1445 transgenic cotton line (current commercial line for Roundup Ready® Cotton) was generated using the figwort mosaic virus (FMV) 35S promoter to drive the expression of the CP4 EPSPS gene, and has excellent vegetative tolerance to glyphosate. However, with high glyphosate application rates at developmental stages later than the four-leaf stage (late-stage applications: applications that are inconsistent with the Roundup® labels), RR1445 shows male sterility. Another transgenic cotton line, RR60, was generated using the FMV 35S promoter and the Arabidopsis elongation factor-1, promoter (AtEF1,) for the expression of CP4 EPSPS. RR60 has excellent vegetative and reproductive tolerance to applications of glyphosate at all developmental stages. Histochemical analyses were conducted to examine the male reproductive development at the cellular level of these cotton lines in response to glyphosate applications, and to investigate the correlation between glyphosate injury and the expression of CP4 EPSPS in male reproductive tissues. The expression of CP4 EPSPS in RR60 was found to be strong in all male reproductive cell types. Conversely, CP4 EPSPS expression in RR1445 was low in pollen mother cells, male gametophytes and tapetum, three crucial male reproductive cell types. Our results indicate that the FMV 35S promoter, although expressing strongly in most vegetative tissues in plants, has extremely low activity in these cell types. [source] Production and characterization of an amphiploid between common wheat and Psathyrostachys huashanica Keng ex KuoPLANT BREEDING, Issue 1 2009H. Y. Kang Abstract Wide crosses and synthetic amphiploids have played an important role in introgressing desirable traits from related species into cultivated wheat. Hybrids between Triticum aestivum cv. ,J-11' and Psathyrostachys huashanica were treated with colchicine, to produce a new intergeneric amphiploid (PHW-SA). The morphological characteristics of PHW-SA resembled the parent ,J-11'. PHW-SA plants have purple internodes and pubescence in the basal spikelet, inherited from the P. huashanica parent. Somatic chromosome numbers varied from 2n = 51 to 2n = 56, with 70.59% of plants having 56 chromosomes. At metaphase I, PHW-SA (2n = 56) plants showed an average of 1.15 univalents, 27.34 bivalents, 0.03 trivalents and 0.02 tetravalents per cell; complete chromosome pairing occurred in 50% of the pollen mother cells. A survey of disease resistances revealed that the stripe rust resistance from P. huashanica was expressed, but powdery mildew resistance was suppressed. The fertility of PHW-SA was 60%. [source] Homoeological relationships between the f chromosome of Brassica rapa and the e chromosome of Brassica oleraceaPLANT BREEDING, Issue 2 2002Y. Kaneko Abstract Eight plants of the putative double monosomic addition line (DMAL, 2n= 20) were developed by crossing a monosomic chromosome addition line of radish [f(A)-type monosomic addition line (MAL) (2n= 19)] carrying the f chromosome of Brassica rapa (2n= 20, AA) with another [e(C)-type MAL (2n= 19)] having the echromosome of Brassica oleracea (2n= 18, CC). The homoeological relationships between the two alien chromosomes were investigated by morphological, cytogenetic and random amplified polymorphic DNA (RAPD) analysis. Seventeen morphological traits that were not present in the radish cv. ,Shogoin' were observed in both MALs and these traits were substantially exhibited in DMAL plants. At the first metaphase of pollen mother cells (PMCs), the two parental MALs showed a chromosome configuration of 9II +1I, demonstrating impossibility of recombination between the R and the added chromosomes. The DMALs formed 10II in approximately 73% of PMCs, with one bivalent showing loose pairing between two chromosomes differing in size. In an attempt to identify the two MALs by RAPD-specific markers using 26 selected random primers, 13 and 20 bands were specific for the f(A)-type and the e(C)-type MALs, respectively; 12 bands were common to both MALs (26.7%). In conclusion, the f chromosome of B. rapa is homoeologous to the e chromosome of B. oleracea. The genetic domain (genes) for 17 morphological traits are linked to each homoeologous chromosome bearing 27% of the corresponding RAPD markers. [source] Effect of the ph1b mutant on chromosome pairing in hybrids between Dasypyrum villosum and Triticum aestivumPLANT BREEDING, Issue 4 2001M. Q. Yu Abstract Chromosome pairing was analysed in F1 hybrids of the wheat cultivar ,Chinese Spring' (CS) and its ph1b mutant (CSphlb) with Dasypyrum villosum. On average, 1.61 chromosomes per cell paired in the hybrid CS ×D. villosum, but 14.43 in the hybrid CS ph1b×D. villosum. Genomic fluorescence in situ hybridization (GISH) revealed three types of homoeologous association between wheat (W) and D. villosum (D) chromosomes (W-D, D-W-W and D-W-D) in pollen mother cells of the CS ph1b×D. villosum hybrid, and only one type (W-W), in the CS ×D. villosum hybrid. Both F1 hybrids were self-sterile. The seed set of the backcross of CS ×D. villosum with CS was 6.67% and that of CS ph1b×D. villosum with CS or CS ph1b was only 0.45%. The chromosome number of BC1 plants varied from 48 to 72. Translocations of chromosome segments or entire arms between wheat and D. villosum chromosomes were detected by GISH in the BC1 plants from the backcross of CS ph1b×D. villosum to CS ph1b. [source] Histological investigation of stripe rust (Puccinia striiformis f.sp. tritici) development in resistant and susceptible wheat cultivarsPLANT PATHOLOGY, Issue 4 2006J. Moldenhauer The wheat cultivar Kariega expresses complete adult plant resistance against stripe rust, whereas cv. Avocet S is susceptible. Using confocal laser scanning microscopy, initial fungal penetration into flag leaves was identical in both cultivars, with directional germ-tube growth towards stomata that were penetrated without the formation of an appressorium, followed by differentiation of a substomatal vesicle, infection hyphae, haustorial mother cells and haustoria. During the following 4 days, further fungal development occurred more quickly in the resistant than in the susceptible cultivar. However, by 7 days postinoculation (dpi) the situation changed, with exponential growth of the pathogen occurring only in the susceptible line. Induced cellular lignification, a typical defence reaction of cereals, was observed at 4 dpi in the resistant cultivar, and 2 days later lignified tissue completely surrounded the fungal colonies. In the susceptible cultivar, isolated lignified host cells occurred at 6 dpi, and long, unbranched fungal hyphae outgrowing the resistance reaction were observed. [source] Embryology of Hortonioideae and Monimioideae (Monimiaceae, Laurales): characteristics of the ,lower' monimioidsBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2008YUKITOSHI KIMOTO We investigated the embryology of the ,lower' monimioids, i.e. Monimioideae (Monimia, Palmeria and Peumus) and Hortonioideae (Hortonia), which are poorly described embryologically. Our results show that, contrary to what has been reported in the literature, ,lower' monimioids show very little variation in their embryological characters. Comparisons with Mollinedioideae (a large derived subfamily in Monimiaceae) and other families in Laurales show that the ,lower' monimioids are relatively consistent in sharing predominantly isobilateral tetrads of microspores and megaspores, a non-specialized chalaza, and a mesotestal,endotestal seed coat (with tracheoidal cells of the meso- and endotesta). It is likely that, while the shared successive cytokinesis during meiosis of microspore mother cells supports the Monimiaceae,Hernandiaceae,Lauraceae clade obtained by molecular evidence, no synapomorphies exist to support a sister-group relationship of Monimiaceae with Hernandiaceae or Lauraceae. Instead, the lack of hypostase in ovules and/or young seeds, the lack of endosperm in mature seeds and the amoeboid tapetum in the anther are likely synapomorphies of Hernandiaceae and Lauraceae. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 228,241. [source] | ||||||||||||||||||||||