scholarly journals An image analysis method to survey the dynamics of polar protein abundance in the regulation of tip growth

2020 ◽  
Vol 133 (22) ◽  
pp. jcs252064 ◽  
Author(s):  
Sarah Taheraly ◽  
Dmitry Ershov ◽  
Serge Dmitrieff ◽  
Nicolas Minc
Keyword(s):  
Cell Wall ◽  
Image Analysis ◽  
Rho Gtpases ◽  
Tip Growth ◽  
Control Cell ◽  
Large Data ◽  
Life Cycles ◽  
Growth Speed ◽  
Protein Abundance ◽  
Canonical Surface

ABSTRACTTip growth is critical for the lifestyle of many walled cells. In yeast and fungi, this process is typically associated with the polarized deposition of conserved tip factors, including landmarks, Rho GTPases, cytoskeleton regulators, and membrane and cell wall remodelers. Because tip growth speeds may vary extensively between life cycles or species, we asked whether the local amount of specific polar elements could determine or limit tip growth speeds. Using the model fission yeast, we developed a quantitative image analysis pipeline to dynamically correlate single tip elongation speeds and polar protein abundance in large data sets. We found that polarity landmarks are typically diluted by growth. In contrast, tip growth speed is positively correlated with the local amount of factors related to actin, secretion or cell wall remodeling, but, surprisingly, exhibits long saturation plateaus above certain concentrations of those factors. Similar saturation observed for Spitzenkörper components in much faster growing fungal hyphae suggests that elements independent of canonical surface remodelers may limit single tip growth. This work provides standardized methods and resources to decipher the complex mechanisms that control cell growth.This article has an associated First Person interview with Sarah Taheraly, joint first author of the paper.

scholarly journals First person – Sarah Taheraly

2020 ◽  
Vol 133 (22) ◽  
pp. jcs256677
Keyword(s):  
Image Analysis ◽  
Cell Biology ◽  
Tip Growth ◽  
Early Career ◽  
First Person ◽  
Protein Abundance ◽  
Analysis Method ◽  
Image Analysis Method ◽  
Early Career Researchers ◽  
Selection Of

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Sarah Taheraly is first author on ‘An image analysis method to survey the dynamics of polar protein abundance in the regulation of tip growth’, published in JCS. Sarah conducted the research described in this article while an Engineer in Biology and Health in the lab of Nicolas Minc, at the Institut Jacques Monod, Paris, France. She now works in the lab of Philippe Benaroch at the Institut Curie, Paris, as an motivated engineer interested in cell biology, immunology, genetics and astronomy.

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.

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 Cell-Biological Studies of Osmotic Shock Response in Streptomyces spp

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Katsuya Fuchino ◽  
Klas Flärdh ◽  
Paul Dyson ◽  
Nora Ausmees
Keyword(s):  
Cell Wall ◽  
Cell Polarity ◽  
Tip Growth ◽  
Biological Study ◽  
Polar Growth ◽  
Hyphal Branching ◽  
Content Type ◽  
Biological Studies ◽  
Wide Range ◽  
Tip Extension

ABSTRACT Most bacteria are likely to face osmotic challenges, but there is yet much to learn about how such environmental changes affect the architecture of bacterial cells. Here, we report a cell-biological study in model organisms of the genus Streptomyces, which are actinobacteria that grow in a highly polarized fashion to form branching hyphae. The characteristic apical growth of Streptomyces hyphae is orchestrated by protein assemblies, called polarisomes, which contain coiled-coil proteins DivIVA and Scy, and recruit cell wall synthesis complexes and the stress-bearing cytoskeleton of FilP to the tip regions of the hyphae. We monitored cell growth and cell-architectural changes by time-lapse microscopy in osmotic upshift experiments. Hyperosmotic shock caused arrest of growth, loss of turgor, and hypercondensation of chromosomes. The recovery period was protracted, presumably due to the dehydrated state of the cytoplasm, before hyphae could restore their turgor and start to grow again. In most hyphae, this regrowth did not take place at the original hyphal tips. Instead, cell polarity was reprogrammed, and polarisomes were redistributed to new sites, leading to the emergence of multiple lateral branches from which growth occurred. Factors known to regulate the branching pattern of Streptomyces hyphae, such as the serine/threonine kinase AfsK and Scy, were not involved in reprogramming of cell polarity, indicating that different mechanisms may act under different environmental conditions to control hyphal branching. Our observations of hyphal morphology during the stress response indicate that turgor and sufficient hydration of cytoplasm are required for Streptomyces tip growth. IMPORTANCE Polar growth is an intricate manner of growth for accomplishing a complicated morphology, employed by a wide range of organisms across the kingdoms of life. The tip extension of Streptomyces hyphae is one of the most pronounced examples of polar growth among bacteria. The expansion of the cell wall by tip extension is thought to be facilitated by the turgor pressure, but it was unknown how external osmotic change influences Streptomyces tip growth. We report here that severe hyperosmotic stress causes cessation of growth, followed by reprogramming of cell polarity and rearrangement of growth zones to promote lateral hyphal branching. This phenomenon may represent a strategy of hyphal organisms to avoid osmotic stress encountered by the growing hyphal tip.

scholarly journals 224 Automatic image feature extraction for genetic analysis in cattle

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 47-47
Author(s):  
Jessica Nye ◽  
Laura Zingaretti ◽  
Miguel Perez-Enciso
Keyword(s):  
Image Analysis ◽  
Image Segmentation ◽  
Genetic Analysis ◽  
Coat Color ◽  
Large Data ◽  
Image Feature ◽  
Background Information ◽  
Pedigree Data ◽  
Require Time ◽  
Composite Method

Abstract Image analysis has increasingly become an important tool for increasing productivity in many industries, yet its application in breeding programs is under utilized. With coat color patterns from dairy bull images, we explore automatic image analysis that extracts features which can be used in genetic analysis. In order to remove the unnecessary background information, the current methods require time consuming human inspection. Here, we present and compare a composite method that creates a mask (i.e., removes the background portion of the image) and calculates the proportion of dark and light coloration in bulls (n = 657) from the breeds Holstein and Ayrshire in dynamic backgrounds (e.g., forest, grass, hay, snow, etc.). This composite method combines the supervised algorithm MASK-RCNN, an unsupervised image segmentation approach, and k-means color clustering. The first step identifies the region of interest removing the majority of the background noise, while the second and third steps optimize the identification of the bull and segments the color patterning. We find a very low discrepancy between the proportion of white and dark between the manual curation and the composite method (+/- 1.40%); with an immense reduction in data collection time. This automatic composite method greatly improves the efficiency of complex image segmentation and analysis without compromising the quality of the data extracted, making analysis computationally feasible for large data sets. The next step is to calculate genetic parameters from these extracted phenotypes with genomic and/or pedigree data.

scholarly journals Resolving Clinicians’ Queries Across a Grid’s Infrastructure

2005 ◽  
Vol 44 (02) ◽  
pp. 149-153 ◽  
Author(s):  
F. Estrella ◽  
C. del Frate ◽  
T. Hauer ◽  
M. Odeh ◽  
D. Rogulin ◽  
...  
Keyword(s):  
Image Analysis ◽  
Data Storage ◽  
Medical Image ◽  
Large Scale ◽  
Medical Image Analysis ◽  
Large Data ◽  
Computing Power ◽  
European Database ◽  
Order Of Magnitude ◽  
Network Speed

Summary Objectives: The past decade has witnessed order of magnitude increases in computing power, data storage capacity and network speed, giving birth to applications which may handle large data volumes of increased complexity, distributed over the internet. Methods: Medical image analysis is one of the areas for which this unique opportunity likely brings revolutionary advances both for the scientist’s research study and the clinician’s everyday work. Grids [1] computing promises to resolve many of the difficulties in facilitating medical image analysis to allow radiologists to collaborate without having to co-locate. Results: The EU-funded MammoGrid project [2] aims to investigate the feasibility of developing a Grid-enabled European database of mammograms and provide an information infrastructure which federates multiple mammogram databases. This will enable clinicians to develop new common, collaborative and co-operative approaches to the analysis of mammographic data. Conclusion: This paper focuses on one of the key requirements for large-scale distributed mammogram analysis: resolving queries across a grid-connected federation of images.

scholarly journals Modification of Expansin Protein Abundance in Tomato Fruit Alters Softening and Cell Wall Polymer Metabolism during Ripening

1999 ◽  
Vol 11 (11) ◽  
pp. 2203-2216 ◽  
Author(s):  
David A. Brummell ◽  
Mark H. Harpster ◽  
Pedro M. Civello ◽  
Joseph M. Palys ◽  
Alan B. Bennett ◽  
...  
Keyword(s):  
Cell Wall ◽  
Tomato Fruit ◽  
Protein Abundance ◽  
Cell Wall Polymer

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

Why Measure Osmotic Adjustment?

1988 ◽  
Vol 15 (6) ◽  
pp. 717 ◽  
Author(s):  
R Munns
Keyword(s):  
Cell Wall ◽  
Stomatal Conductance ◽  
Osmotic Adjustment ◽  
Cell Expansion ◽  
Control Cell ◽  
Growth Yield ◽  
Future Research ◽  
Saline Soils ◽  
Cell Wall Synthesis ◽  
Adaptation To Drought

Osmotic adjustment (erroneously called 'osmoregulation') is generally regarded as an important adaptation to drought or salinity. Because it helps to maintain turgor and cell volume, it is often thought to promote growth, yield, or survival, of plants in dry or saline soils. However, a physiological rationale for such views is lacking. Osmotic adjustment itself cannot promote growth; the solutes which account for it must be diverted from essential processes such as protein and cell wall synthesis. Further, it now appears that turgor does not control cell expansion or stomatal conductance. Thus, osmotic adjustment cannot affect yields except via other processes, the controls of which are almost entirely unexplored. Future research in this area should test hypotheses, rather than merely measure osmotic adjustment.

scholarly journals Self-regulation in tip-growth: The role of cell wall ageing

2011 ◽  
Vol 283 (1) ◽  
pp. 113-121 ◽  
Author(s):  
Eelco Eggen ◽  
M. Niels de Keijzer ◽  
Bela M. Mulder
Keyword(s):  
Cell Wall ◽  
Tip Growth ◽  
Self Regulation
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