How do zoospores respond to external stimuli?
Zoospores are specialized for short-distance dispersal, responding to external stimuli, such as root exudates (chemotaxis), for identifying suitable penetration sites, where they encyst and initiate new infections. Zoospores of the phytopathogenic fungi Pythium and Phytophthora are attracted to plant roots and root exudates.
What is the velocity of a zoospore?
Zoospore propulsion is driven by high-frequency undulation of the flagellum from base to the tail and a velocity of 100 μm per second (20-times cell length per second) is typical for a chytrid. Zoospores can swim for many hours in a culture dish or glass microscope chamber.
What are the characteristics of zoospores?
Zoospores are biflagellate and produced in unspecialized cells and released through a pore. Zoospores of the phytopathogenic fungi Pythium and Phytophthora are attracted to plant roots and root exudates.
What is the taxonomy of the zoosporic fungi with zoospores?
Zoospores are produced by Blastocladiomycota, Chytridiomycota, Neocallimastigomycota, and diverse zoosporic fungi of uncertain taxonomic assignment included in the Cryptomycota ( Chapter 1 ).
What is a zoospore?
Zoospores are specialized for short-distance dispersal, responding to external stimuli, such as root exudates (chemotaxis), for identifying suitable penetration sites, where they encyst and initiate new infections. From: Encyclopedia of Microbiology (Third Edition), 2009. Download as PDF.
Which supergrouping contains zoospores?
This is the structural signature of the Opisthokonta supergrouping that encompasses the fungi and animals. Zoospores are produced by Blastocladiomycota, Chytridiomycota, Neocallimastigomycota, and diverse zoosporic fungi of uncertain taxonomic assignment included in the Cryptomycota ( Chapter 1 ).
How fast do zoospores swim?
Zoospores can swim for many hours in a culture dish or glass microscope chamber.
What attractants are zoospores attracted to?
4.13.2.3.1 Host-specific zoospore attractants. Zoospores of the phytopathogenic fungi Pythium and Phytophthora are attracted to plant roots and root exudates. The first description of attractants other than nutrients such as amino acids and sugars was an extensive investigation on chemical products including alcohols, aldehydes, ...
How does epizootiology transmit?
Epizootiology and Transmission. Transmission occurs via flagellated, infective zoospores that require water or moist conditions for movement or direct contact of animals. Research suggests that the movement of Xenopus spp. throughout the world contributed to its spread.
Where are zoospores found?
Exceptions to the uniflagellate structure of fungal zoospores are found in some of the anaerobic gut fungi in the Neocallimastigomycota that produce spores with multiple flagella. The majority of zoospores function in dispersal and allow the fungus to locate new sources of nutrients.
What are the host factors that influence susceptibility to infection?
Host factors that influence susceptibility to infection include poor body condition, malnutrition, 38-40 stressful conditions , and glucocorticoids. 41 Any disruption in the skin barrier due to trauma (e.g., insect bites, pruritus due to other conditions) can facilitate the establishment of the infection.
How many logs does sterilization kill?
Sterilization means a kill of at least 6+ Log
What is a 6.0 log?
Hospital surfaces can be contaminated with pathogenic organisms (bio-burden), and only achieving a Log Reduction below 6.0 Log means dangerous viruses, bacteria, fungus, and Clostridium difficile (C-diff) spores, can or will be left behind to proliferate and repopulate surfaces within the treated area. The literature has shown that bio-burden can be spread around to contaminate patients and/or grow new bacterial and fungal colonies on new surfaces. (1)
What is broad spectrum disinfectant?
DEFINITION: General or broad spectrum efficacy products - When a disinfectant is represented in labeling as having efficacy against both Gram-negative and Gram-positive bacteria, the product is considered a “general orbroad spectrum” disinfectant .
How much water does a large scale treatment plant process?
Yu agrees that the threat is low, but adds that some large-scale treatment plants process about 1 billion L water per day. Therefore, such plants could still end up releasing many dormant bacteria that could then wake up and share virulence genes with their neighbors.
Is UV light used in China?
But in China, UV alone is used in many small-scale drinking water facilities and for point-of-use disinfection, Yu says, and it’s being proposed as an effective alternative to chlorination on a larger scale.
What are the limitations of the USP pyrogen test?
The USP pyrogen test has additional limitations besides endotoxin tolerance and low reactivity to legionnaires' endotoxin. Among these are its variability in test results when compared to the same preparation of standardized endotoxin.
What is the USP test for rabbits?
The USP now recognizes two tests - The Pyrogen Test conducted with rabbits and the Bacterial Endotoxins Test , also termed the Limulus Amebocyte Lysate (LAL) Test. Additionally, the agency has approved the use of the Bacterial Endotoxins Test for many drug and device products.
What are the benefits of the Bacterial Endotoxins Test?
The agency has recognized the benefits of the Bacterial Endotoxins Test, particularly with respect to sensitivity, reproducibility, scope and simplicity. Additionally, both FDA inspections and FDA testing programs have identified objectionable levels of endotoxin in drugs and devices.
When was the USP XX revised?
Subsequently, the draft guideline was revised and reissued in 1983. The USP XX, 5th supplement, revised the Bacterial Endotoxins Test. However, unlike the FDA draft guideline, no retest provisions were included. Most manufacturers are at some stage of validating the Bacterial Endotoxin Test for their products.
Is it better to remove endotoxins from finished products?
It is difficult to remove endotoxins from products once present. It is far better to keep finished products and components relatively endotoxin-free rather than have to remove it once present.