Chapter 11: Gnotobiotics Flashcards
What does the term “gnotobiotics” mean?
Well-known life
True or False
A germ-free animal is a type of gnotobiote
True
True or False
Axenic rats are not available commercially; they must be developed within the individual animal facility.
False
Identify at least four sterilization methods used to support gnotobiotic systems
1- steam autoclaving
2- dry heat
3- peracetic acid
4- ethylene oxide
Define “axenic animal”
An animal free of all demonstrable microorganisms
What is different about an axenic animal’s cecum from other animals?
The axenic animal has a greatly enlarged cecum
Are all gnotobiotes axenic? Why or why not?
No. Axenic or germ-free animals are only one type of gnotobiote. Defined flora animals are also gnotobiotes.
Describe the process of embryo transfer for deriving an axenic animal.
The embryos from a superovulated mother are removed, washed, and transferred to the reproductive tract of a psuedopregnant axenic female in a surgical isolator
Why should you use a foster mother whose coat color is different from the donor mother in a hysterectomy derivation to produce axenic animals?
To make sure the fostered pups are distinguishable from the foster mother’s own litter
What is a Schaedler cocktail and why is it given to axenic animals?
The cocktail of normal symbiotic (nonpathogenic) intestinal bacteria is given to normalize the gut physiology and anatomy
What is a transfer sleeve?
A flexible plastic tube of the same diameter as the entry port and the supply cylinder
Which of the following are true of axenic animals as compared to animals with normal micro flora? Choose all that apply to axenic animals.
A- they have lower white blood cell counts
B- their cecal content is more acidic
C- their cholesterol level is generally higher
D- their thymus is smaller
E- their cecum is smaller
F- their intestinal walls are thicker
A- they have lower white blood cell counts
C- their cholesterol level is generally higher
D- their thymus is smaller
How do litter sizes compare between axenic and defined flora animals?
Axenic animals generally have smaller litters
Axenic animals require more vitamins ________ and _________, and have lower requirements for vitamins ________ and _________.
K and B
A and E
What is a major advantage of flexible isolators compared to rigid isolators?
A- They offer better protection against contamination
B- They are less expensive to manufacture
C- They are easier to disinfect and sterilize
D- They are longer-lasting
B- They are less expensive to manufacture
Animals that have a normal intestinal flora but are free of particular organisms are called: A- defined flora B- axenic C- normal D- specific pathogen free
D- specific pathogen free
Which of the following is NOT an appropriate sterilization method for gnotobiotic systems? A- peracetic acid B- steam autoclaving C- carbon dioxide D- membrane filtration of liquids
C- carbon dioxide
The most basic requirement for an isolator is that it must be: A- impervious B- transparent C- rigid D- impact-resistant
A- impervious
What function does a transfer sleeve serve?
A- to control the speed of the transfer of material into the isolator
B- to sterilize the materials before placing them in the isolator
C- to connect the supply cylinder to the isolator entry port
D- to remove airborne microorganisms from the room air
C- to connect the supply cylinder to the isolator entry port
Which vitamins are required in lesser quantities in axenic animals? A- B vitamins and vitamin K B- vitamin A and vitamin E C- vitamin C and vitamin D D- vitamins B1 and B12
B- vitamin A and vitamin E
What is the advantage of giving gnotobiotics a cocktail containing normal intestinal flora?
A- it makes their decal content more acidic
B- it protects them from infection
C- it serves to normalize the gut physiology and anatomy
D- it helps regulate their immune system
C- it serves to normalize the gut physiology and anatomy
Why are foundation colonies generally maintained in the defined flora state instead of in the axenic state? A- to maintain genetic integrity B- to optimize litter size C- to study the progression of infection D- to improve immunity of the animals
B- to optimize litter size
Animals that were originally germ-free but were given a known group of bacteria are called known as what type of animals? A- axenic B- defined flora C- specific pathogen free D- normal
B- defined flora
Which statement is true of axenic animals as compared to animals with normal microflora?
A- their decal content is more acidic
B- they have lower white blood cell counts
C- their cholesterol level is generally lower
D- their thymuses are bigger
B- they have lower white blood cell counts
