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.
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Famous quotes containing the words cell, walls, water and/or slime:
“A cell for prayer, a hall for joy,
They treated nature as they would.”
—Ralph Waldo Emerson (18031882)
“The harp that once through Taras halls The soul of music shed, Now hangs as mute on Taras walls As if that soul were fled.”
—Thomas Moore (17791852)
“I respect the ways of old folks, but the blood of a rooster or a goat cannot turn the seasons, change the course of the clouds and fill them up with water like bladders. The other night, at the ceremony for Legba, I danced and sang my fill: I am a black man, no? and I enjoyed it like a true Negro should. When the drums beat, I feel it in the pit of my stomach, I feel the itch in my hips and up and down my legs, I have got to join the party. But that is all.”
—Jacques Roumain (19071945)
“Let the space under the first storey be dark, let the water
lap the stone posts, and vivid green slime glimmer
upon them; let a boat be kept there.”
—Denise Levertov (b. 1923)