Rodents (1996) / Chapter Skim
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3 CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS
3 CRITERIA FOR SELECTING EXPERIMENTAL ANIMALS
Pages 16-34
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From page 16... ...
In which species is the physiologic, metabolic, behavioral, or disease process to be studied most similar to that of humans or other animals to which the results of the studies will be applied? · Do other species possess biologic or behavioral characteristics that make them more suitable for the planned studies (e.g., generation time and availability'?
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From page 17... ...
In studies that are mechanistic, genetic uniformity is highly desirable. In contrast, genetic uniformity might be undesirable in studies that explore the diversity 1 laboratory mice are neither pure Mus domesticus nor pure Mus musculus; therefore, geneticists have determined that there is no appropriate scientific name (International Committee on Standardized Genetic Nomenclature for Mice, 1994a)
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From page 18... ...
Genetically Defined Stocks Inbred Strains. The mating of any related animals will result in inbreeding, but the most common and efficacious method for establishing and maintaining an inbred strain is brother x sister (i.e., full-sib)
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From page 19... ...
To avoid subline divergence between the coisogenic strain and the nonmutant parental inbred strain, periodic back-cro$sing (see next paragraph) with the parental strain is recommended.
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From page 20... ...
· Recombinant congenic strains are like recombinant inbred strains except that each strain of a series has been derived from a back-cross instead of an F2 cross (Demant, 1986~. The number of back-crosses made before full-sib inbreeding is started determines the proportion of genes from each of the parental inbred strains.
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From page 21... ...
Investigators using other laboratory rodents should follow the rules for mice or rats. Inbred Strains An inbred strain is designated by capital letters (e.g., mouse strains AKR and CBA and rat strains BN and LEW)
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From page 22... ...
Mice. A particular colony is indicated by appending an "@" sign and the laboratory code to the end of the strain or substrain symbol (e.g., SJL@J, the colony of strain SJL mice bred at the Jackson Laboratory; C3H/ He@N, the He substrain of strain C3H bred at the NIH Genetic Resource; and CBA/Ca-se@J, the Ca substrain of strain CBA carrying the se mutation and bred at the Jackson Laboratory)
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From page 23... ...
and F344/NNia x BN/RijNia F1 (hereafter called FBNF1~. Coisogenic, Congenic, and Segregating Inbred Strains In mice, a coisogenic strain is designated by the strain symbol, the substrain symbol (if any)
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From page 24... ...
Gene designations are appended to the designation of the parental strain, and they are separated by a hyphen. Loci That Are Members of a Series A locus that is a member of a series whose members specify similar proteins or other characteristics is designated by the same letter symbol and a distinguishing number (e.g., Esl, Es2, and Es3 in mice and Esl, Es2, and Es3 in rats)
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From page 25... ...
When a targeted mutation introduced by homologous recombination does not involve the insertion of a novel functional sequence, the new mutant allele (the knockout mutation) is designated in accordance with the guidelines for gene nomenclature for each species.
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From page 26... ...
. In this example, the transgenic insertion, even if it contains a functional neomycinresistance gene, is incidental to "knocking out" or mutating the targeted locus (see also International Committee on Standardized Genetic Nomenclature for Mice, 1994b)
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From page 27... ...
As an exception, a stock derived by outbreeding a formerly inbred strain may continue to use the original symbol; in this case, the laboratory code preceding the stock symbol characterizes the stock as outbred. An outbred stock that contains a specified mutation is designated by the laboratory code, a colon, the stock symbol, a hyphen, and the gene symbol (e.g., Crl:ZUC-fa)
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From page 28... ...
The quality of laboratory animals is generally related to the microbiologic exclusion methods used to breed and maintain them. There are three major types of maintenance: isolator-maintained, barrier-maintained, and no-containment or conventionally maintained animals.
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From page 29... ...
This method of maintaining animals cannot ensure stability of the microbiologic status, because unwanted organisms can be introduced at any time. Several classifications have been developed to define the microbiologic quality of laboratory animals, as follows (see also NRC, 1991~: · Axenic refers to animals that are derived by cesarean section or embryo transfer and reared and maintained in an isolator with aseptic techniques.
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From page 30... ...
Genetic monitoring consists of any method used to ensure that the genetic integrity of individuals of any particular strain has not been violated. Several commercial sources provide genetic monitoring services for inbred mouse and rat strains.
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From page 31... ...
A good breeding-management program, as described in Chapter 4, will help to reduce unwanted genetic changes caused by mutations. SELECTED ASPECTS OF EXPERIMENTAL DESIGN An experiment in which laboratory animals are used should be designed carefully, so that it produces unequivocal information about the questions that it was designed to address.
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From page 32... ...
The more variable an outcome measure is, either because outcomes in identically treated animals vary substantially or because there is a high degree of measurement variability, the more animals will be needed in each group to distinguish between group differences caused by treatment and those caused by chance. How outcome measurement variability, treatment difference to be detected, and tolerable chance of drawing an erroneous conclusion affect the required sample size depends on the measurement to be made' the type of croup comparison to be made.
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From page 33... ...
1981. Recombinant inbred strains and bilinear congenic strains.
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From page 34... ...
1994a. Rules for nomenclature of inbred strains.
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