scholarly journals Morphogenesis in Micrasterias

Development ◽  
1975 ◽  
Vol 33 (1) ◽  
pp. 95-115
Author(s):  
T. C. Lacalli
Keyword(s):  
Cell Wall ◽  
Tip Growth ◽  
Primary Cell Wall ◽  
Growth Stages ◽  
Primary Wall ◽  
Spatial Form ◽  
Laser Microbeam ◽  
Stage 4 ◽  
Fungal Hyphae ◽  
Per Se

Observations on lobe growth in the lateral wings of the developing primary cell wall in the desmid Micrasterias rotata are reported and discussed. Patterns of incorporation of methyl-[3H]methionine and C-1-[3H] glucose into the primary wall as revealed in autoradiograms indicate that formation of the new wall is concentrated at the tips of lobes. Patterns follow the predictions of Robertson's model for tip growth in fungal hyphae; thus they link growth in M. rotata lobes with mechanisms of cell elongation found in other cells. Damage done to selected regions of the cell surface with a laser microbeam demonstrates that only certain regions are required for continued growth and morphogenesis while much of the surface plays only a passive role. In growth stages at which lobes are already well defined (stage 4 and later) continued growth of each lobe requires the participation of an area no more than 4–5 µm in diameter, here termed a singularity, at its tip. At early stages (prior to stage 3) singularities per se cannot be demonstrated. At these stages the capacity to initiate lobes and hence to form singularities is not fixed at specific points, but is distributed over an area of the surface no less than 10 µm in diameter. Singularities, by their persistence and repeated duplication, are directly responsible for the spatial form of the two lateral wings.

scholarly journals Mapping the Growth of Fungal Hyphae: Orthogonal Cell Wall Expansion during Tip Growth and the Role of Turgor

2000 ◽  
Vol 79 (5) ◽  
pp. 2382-2390 ◽  
Author(s):  
Salomon Bartnicki-Garcia ◽  
Charles E. Bracker ◽  
Gerhard Gierz ◽  
Rosamaría López-Franco ◽  
Haisheng Lu
Keyword(s):  
Cell Wall ◽  
Tip Growth ◽  
Fungal Hyphae ◽  
Cell Wall Expansion

Ontogeny of spore markings on aeciospores of Cronartium comandrae and peridermioid teliospores of Endocronartium harknessii

1974 ◽  
Vol 52 (8) ◽  
pp. 1919-1921 ◽  
Author(s):  
D. M. Henderson ◽  
Yasuyuki Hiratsuka
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Primary Cell ◽  
Primary Cell Wall ◽  
Primary Wall ◽  
Transmission Electron ◽  
Endocronartium Harknessii

Aeciospores of Cronartium comandrae Pk. and peridermioid teliospores of Endocronartium harknessii (J. P. Moore) Y. Hiratsuka were studied under the transmission electron microscope. Spores are ornamented by growth of hyaline structures within a growing primary cell wall. The ornamentation is subsequently exposed by the removal of the primary wall matrix, presumably by reabsorption.

scholarly journals Pollen tube growth and guidance: Occam’s razor sharpened on a molecular AGP Rosetta Stone

2017 ◽  
Author(s):  
Derek T. A. Lamport ◽  
Li Tan ◽  
Michael Held ◽  
Marcia J. Kieliszewski
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Pollen Tube ◽  
Tip Growth ◽  
Force Transducer ◽  
Primary Cell Wall ◽  
Rosetta Stone ◽  
Occam’S Razor ◽  
Tube Guide ◽  
Occam's Razor

ABSTRACTOccam’s Razor suggests a new model of pollen tube tip growth based on a novel Hechtian oscillator that integrates: (1) a periplasmic AGP-Ca2+calcium capacitor with tip-localised arabinogalactan glycoproteins (AGPs); (2) tip-focussed cytosolic Ca2+oscillations; (3) Hechtian strands evidence of adhesion between the plasma membrane and the cell wall of the growing tip. Thus Hechtian adhesion, as a piconewton force transducer, couples the internal stress of a rapidly growing wall to the plasma membrane. Such Hechtian transduction via stretch-activated Ca2+channels and H+-ATPase proton efflux dissociating periplasmic AGP-Ca2+, creates a Ca2+influx that activates exocytosis of wall precursors. In effect a highly simplified primary cell wall regulates its own synthesis and a Hechtian growth oscillator regulates overall tip growth. By analogy with the Rosetta Stone that translates trilingual inscriptions as a single identical proclamation, the Hechtian Hypothesis translates classical AGPs and their roles as a Ca2+capacitor, pollen tube guide and wall plasticiser into a simple but widely applicable model of tip growth. Even wider ramifications of the Hechtian oscillator may implicate AGPs in osmosensing or gravisensing and other tropisms, leading us yet further towards the Holy Grail of plant growth.

Ultrastructure of the pycnial and aecial stages of Puccinia recondita

1979 ◽  
Vol 57 (1) ◽  
pp. 74-86 ◽  
Author(s):  
R. E. Gold ◽  
L. J. Littlefield ◽  
G. D. Statler
Keyword(s):  
Cell Wall ◽  
Leaf Tissue ◽  
Mature Spore ◽  
Host Cells ◽  
Puccinia Recondita ◽  
Primary Cell Wall ◽  
Outer Cell ◽  
Primary Wall ◽  
Wide Diameter ◽  
Electron Lucent

The haploid stage of Puccinia recondita in Thalictrum speciosissimum was established by basidiospore infection. Haploid hyphae were inter- and intra-cellular. Intracellular structures arose from intercellular hyphae without prior formation of specialized mother cells. They gained entrance into host cells via wide-diameter penetration sites; they were hyphal-like and formed abundantly in both mesophyll and epidermal cells. Commonly, they exited host cells to become intercellular hyphae or intracellular hyphae in adjacent host cells. Numerous, globose pycnia were borne in wart-like humps on the leaf tissue. Paraphyses and flexuous hyphae extended through the ostiole, initially aggregated into a column, but later become radiate. Globose to oblong aecia developed one to three cells below the lower epidermis of humped leaf tissue. Aeciospore initials arose from a stroma of sporogenous tissue at the base of the aecia. Successive divisions of aeciosporophores produced catenulate aeciospores separated by intercalary cells. The first appearance of aeciospore wall ornaments (verrucae) was associated with the division of aeciospore initials into aeciospores and intercalary cells. The electron-lucent verrucae were contiguous with the spore plasmalemma and enlarged to full size (ca. 0.5 × 0.3 μm) in the primary cell wall. During maturation aeciospores underwent a two- to three-fold increase in diameter and the intercalary cells disintegrated. Simultaneously, the primary wall of the aeciospores broke down, exposing the verrucae. The secondary wall formed centripetal to the disintegrating primary wall to provide the major portion of the mature spore wall. The verrucose, mature aeciospores were globose to elliptical (ca. 16.5 × 19 μm). Germ pores were locally thickened areas within the secondary cell wall and contained small electron-lucent interspersions. The peridial cells which delimit the aecia were differentially thickened. The thick outer cell wall contained dagger-shaped, electron-lucent processes and the relatively thin inner wall was ornamented with smooth, knob-like, electron-lucent clavae.

scholarly journals Setting the boundaries: Primary cell wall synthesis and expansion

2011 ◽  
Vol 33 (2) ◽  
pp. 14-19
Author(s):  
Stephen C. Fry ◽  
Lenka Franková ◽  
Dimitra Chormova
Keyword(s):  
Cell Wall ◽  
Secondary Wall ◽  
Plant Cells ◽  
Wall Layer ◽  
Maximum Amount ◽  
Primary Cell Wall ◽  
Primary Wall ◽  
Cell Wall Synthesis ◽  
Outer Primary ◽  
Shape And Size

Mature plant cells typically have two-layered walls: a first-formed thin outer primary wall layer enclosing a later-formed thick inner secondary wall. The surface area of the primary wall limits the size of the cell and thus the maximum amount of biomass that can potentially be accumulated in the secondary wall. By controlling the shape and size of the cell, the primary wall therefore imposes the limits on the amount of inedible biofuel a plant cell can make.

Potent Chitin Synthase Inhibitors from Plants

2020 ◽  
Vol 16 (1) ◽  
pp. 58-63
Author(s):  
Amrutha Vijayakumar ◽  
Ajith Madhavan ◽  
Chinchu Bose ◽  
Pandurangan Nanjan ◽  
Sindhu S. Kokkal ◽  
...  
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Caenorhabditis Elegans ◽  
Aspergillus Niger ◽  
Small Molecules ◽  
Tip Growth ◽  
Chitin Synthase ◽  
Chitin Synthesis ◽  
Hyphal Tip Growth ◽  
Hyphal Tip

Background: Chitin is the main component of fungal, protozoan and helminth cell wall. They help to maintain the structural and functional characteristics of these organisms. The chitin wall is dynamic and is repaired, rearranged and synthesized as the cells develop. Active synthesis can be noticed during cytokinesis, laying of primary septum, maintenance of lateral cell wall integrity and hyphal tip growth. Chitin synthesis involves coordinated action of two enzymes namely, chitin synthase (that lays new cell wall) and chitinase (that removes the older ones). Since chitin synthase is conserved in different eukaryotic microorganisms that can be a ‘soft target’ for inhibition with small molecules. When chitin synthase is inhibited, it leads to the loss of viability of cells owing to the self- disruption of the cell wall by existing chitinase. Methods: In the described study, small molecules from plant sources were screened for their ability to interfere with hyphal tip growth, by employing Hyphal Tip Burst assay (HTB). Aspergillus niger was used as the model organism. The specific role of these small molecules in interfering with chitin synthesis was established with an in-vitro method. The enzyme required was isolated from Aspergillus niger and its activity was deduced through a novel method involving non-radioactively labelled substrate. The activity of the potential lead molecules were also checked against Candida albicans and Caenorhabditis elegans. The latter was adopted as a surrogate for the pathogenic helminths as it shares similarity with regard to cell wall structure and biochemistry. Moreover, it is widely studied and the methodologies are well established. Results: Out of the 11 compounds and extracts screened, 8 were found to be prospective. They were also found to be effective against Candida albicans and Caenorhabditis elegans. Conclusion: Purified Methyl Ethyl Ketone (MEK) Fraction1 (F1) of Coconut (Cocos nucifera) Shell Extract (COSE) was found to be more effective against Candida albicans with an IC50 value of 3.04 μg/mL and on L4 stage of Caenorhabditis elegans with an IC50 of 77.8 μg/mL.

scholarly journals Effect of Herbicides on the Management of the Invasive Weed Solanum rostratum Dunal (Solanaceae)

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 284
Author(s):  
Jackline Abu-Nassar ◽  
Maor Matzrafi
Keyword(s):  
Growth Stage ◽  
Late Summer ◽  
Early Spring ◽  
Growth Stages ◽  
Weed Species ◽  
Invasive Weed ◽  
Solanum Rostratum ◽  
Stage 4 ◽  
Chemical Solutions ◽  
Late Growth

Solanum rostratum Dunal is an invasive weed species that invaded Israel in the 1950s. The weed appears in several germination flashes, from early spring until late summer. Recently, an increase in its distribution range was observed, alongside the identification of new populations in the northern part of Israel. This study aimed to investigate the efficacy of herbicide application for the control of S. rostratum using two field populations originated from the Golan Heights and the Jezreel Valley. While minor differences in herbicide efficacy were recorded between populations, plant growth stage had a significant effect on herbicide response. Carfentrazone-ethyl was found to be highly effective in controlling plants at both early and late growth stages. Metribuzin, oxadiazon, oxyfluorfen and tembutrione showed reduced efficacy when applied at later growth stage (8–9 cm height), as compared to the application at an early growth stage (4–5 cm height). Tank mixes of oxadiazon and oxyfluorfen with different concentrations of surfactant improved later growth stage plant control. Taken together, our study highlights several herbicides that can improve weed control and may be used as chemical solutions alongside diversified crop rotation options. Thus, they may aid in preventing the spread and further buildup of S. rostratum field populations.

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