Integration and regulation of hyphal tip growth

1995 ◽  
Vol 73 (S1) ◽  
pp. 131-139 ◽  
Author(s):  
I. Brent Heath
Keyword(s):  
Cell Wall ◽  
Tip Growth ◽  
Apical Cell ◽  
Turgor Pressure ◽  
Feedback Regulation ◽  
Regulation Mechanism ◽  
Hyphal Tip Growth ◽  
Species Specific ◽  
Stretch Activated Channels ◽  
Hyphal Tip

Hyphal tip growth is an exquisitely controlled process that forms developmentally regulated, species-specific, even-diameter tubes at rates of up to about 50 μm/min. The traditional view is that this process results from the balance between the expansive force of turgor pressure and the controlled extensibility of the apical cell wall. While these elements are involved, the model places regulation into either the global domain (turgor pressure) or the extracellular environment (the cell wall), neither of which seem well suited to the level of control evinced. Recent evidence suggests that F-actin-rich elements of the cytoskeleton are important in tip morphogenesis. Our current models propose that tip expansion is regulated (restrained under normal turgor pressure and protruded under low turgor) by a peripheral network of F-actin that is attached to the plasmalemma and the cell wall by integrin-containing linkages, thus placing control in the cytoplasm where it is accessible to normal intracellular regulatory systems. The F-actin system also functions in cytoplasmic and organelle motility; control of plasmalemma-located, stretch-activated, Ca2+-transporting, ion channel distribution; vectoral vesicle transport; and exocytosis. Regulation of the system may involve Ca2+, the concentration of which is influenced by the tip-high gradient of the stretch-activated channels, thus suggesting a possible feedback regulation mechanism. Key words: tip growth, fungi, stretch-activated channels, F-actin, Ca2+, hyphae.

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 Exocytosis and endocytosis: coordinating and fine-tuning the polar tip growth domain in pollen tubes

2020 ◽  
Vol 71 (8) ◽  
pp. 2428-2438 ◽  
Author(s):  
Jingzhe Guo ◽  
Zhenbiao Yang
Keyword(s):  
Cell Wall ◽  
Rho Gtpases ◽  
Intracellular Signaling ◽  
Tip Growth ◽  
Apical Cell ◽  
Turgor Pressure ◽  
Pollen Tubes ◽  
Fine Tuning ◽  
Rop Gtpase ◽  
Specialized Form

Abstract Pollen tubes rapidly elongate, penetrate, and navigate through multiple female tissues to reach ovules for sperm delivery by utilizing a specialized form of polar growth known as tip growth. This process requires a battery of cellular activities differentially occurring at the apical growing region of the plasma membrane (PM), such as the differential cellular signaling involving calcium (Ca2+), phospholipids, and ROP-type Rho GTPases, fluctuation of ions and pH, exocytosis and endocytosis, and cell wall construction and remodeling. There is an emerging understanding of how at least some of these activities are coordinated and/or interconnected. The apical active ROP modulates exocytosis to the cell apex for PM and cell wall expansion differentially occurring at the tip. The differentiation of the cell wall involves at least the preferential distribution of deformable pectin polymers to the apex and non-deformable pectin polymers to the shank of pollen tubes, facilitating the apical cell expansion driven by high internal turgor pressure. Recent studies have generated inroads into how the ROP GTPase-based intracellular signaling is coordinated spatiotemporally with the external wall mechanics to maintain the tubular cell shape and how the apical cell wall mechanics are regulated to allow rapid tip growth while maintaining the cell wall integrity under the turgor pressure. Evidence suggests that exocytosis and endocytosis play crucial but distinct roles in this spatiotemporal coordination. In this review, we summarize recent advances in the regulation and coordination of the differential pectin distribution and the apical domain of active ROP by exocytosis and endocytosis in pollen tubes.

scholarly journals Model of hyphal tip growth involving microtubule-based transport

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
K. E. P. Sugden ◽  
M. R. Evans ◽  
W. C. K. Poon ◽  
N. D. Read
Keyword(s):  
Tip Growth ◽  
Hyphal Tip Growth ◽  
Hyphal Tip

Mechanisms of Hyphal Tip Growth and Morphogenesis in the Filamentous Fungus Neurospora crassa

2004 ◽  
Vol 10 (S02) ◽  
pp. 1554-1555
Author(s):  
Maho Uchida ◽  
Solomon Bartnicki-García ◽  
Robert W. Roberson
Keyword(s):  
Neurospora Crassa ◽  
Filamentous Fungus ◽  
Tip Growth ◽  
Hyphal Tip Growth ◽  
Hyphal Tip

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Computer modelling of hyphal tip growth in fungi

1972 ◽  
Vol 50 (12) ◽  
pp. 2455-2462 ◽  
Author(s):  
Daniela da Riva Ricci ◽  
Bryce Kendrick
Keyword(s):  
Mathematical Model ◽  
Tip Growth ◽  
Computer Modelling ◽  
Hyphal Tip Growth ◽  
Hyphal Tip

Starting from simple morphological considerations and a hypothesis involving 'unset' and 'set' wall, a mathematical model simulating the growth of the hyphal tip is derived, and the results displayed by plotter.

scholarly journals The Ashbya gossypii fimbrin SAC6 is required for fast polarized hyphal tip growth and endocytosis

2011 ◽  
Vol 166 (3) ◽  
pp. 137-145 ◽  
Author(s):  
Sigyn Jorde ◽  
Andrea Walther ◽  
Jürgen Wendland
Keyword(s):  
Tip Growth ◽  
Ashbya Gossypii ◽  
Hyphal Tip Growth ◽  
Hyphal Tip
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