Cell Walls of Water and Slime Molds
The group Oomycetes, also known as water molds, are saprotrophic plant pathogens like fungi. Until recently they were widely believed to be fungi, but structural and molecular evidence has led to their reclassification as heterokonts, related to autotrophic brown algae and diatoms. Unlike fungi, oomycetes typically possess cell walls of cellulose and glucans rather than chitin, although some genera (such as Achlya and Saprolegnia) do have chitin in their walls. The fraction of cellulose in the walls is no more than 4 to 20%, far less than the fraction comprised by glucans. Oomycete cell walls also contain the amino acid hydroxyproline, which is not found in fungal cell walls.
The dictyostelids are another group formerly classified among the fungi. They are slime molds that feed as unicellular amoebae, but aggregate into a reproductive stalk and sporangium under certain conditions. Cells of the reproductive stalk, as well as the spores formed at the apex, possess a cellulose wall. The spore wall has been shown to possess three layers, the middle of which is composed primarily of cellulose, and the innermost is sensitive to cellulase and pronase.
Read more about this topic: Cell Wall
Famous quotes containing the words cell, walls, water and/or slime:
“It is plain that there is no separate essence called courage, no cup or cell in the brain, no vessel in the heart containing drops or atoms that make or give this virtue; but it is the right or healthy state of every man, when he is free to do that which is constitutional to him to do.”
—Ralph Waldo Emerson (18031882)
“Do you know what Agelisas said, when he was asked why the great city of Lacedomonie was not girded with walls? Because, pointing out the inhabitants and citizens of the city, so expert in military discipline and so strong and well armed: Here, he said, are the walls of the city, meaning that there is no wall but of bones, and that towns and cities can have no more secure nor stronger wall than the virtue of their citizens and inhabitants.”
—François Rabelais (14941553)
“Reasoning with a drunkard is like
Going under water with a torch to seek for a drowning man.”
—Tiruvalluvar (c. 5th century A.D.)
“All is waste and worthless, till
Arrives the selecting will,
And, out of slime and chaos, Wit
Draws the threads of fair and fit.”
—Ralph Waldo Emerson (18031882)