Cells and Surveys Should Biological Measures Be Included in Social Science Research? (2001) / Chapter Skim
Currently Skimming:
Relevence of Animal Models for Human Populations
Relevence of Animal Models for Human Populations
Pages 213-228
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 213... ...
identifies models as "scientific metaphors" and comments thusly on their usage: "Like every other aspect of scientific procedure, the scientific metaphor is a pragmatic device, to be used freely as long as it serves its purpose to be discarded without regrets when it fails to do so." In the philosophical literature a distinction between conceptual models and physical models is often encountered, and further taxonomic distinctions can be found among analogical, descriptive, explanatory, formal, heuristic, ironic, inferential, interpretive, measuring, predictive, semantical, statistical, symbolic, and syntatical models. Many of these categories are nonexclusive, so any particular model system can be a blend of several types.
|
From page 214... ...
Although plants can also be informative in this type of research (see Finch, 1990) , it has mostly involved other animals, so the generic title is usually given as "animal model research." Species Choice The fundamental rationale for the use of animal models derives from the phyletic relatedness of living things.
|
From page 215... ...
Thus, the animal-model-derived knowledge that has been accumulated in each substantive domain has been filtered through these standard animal groups and perhaps constrained by the sparse sampling we have made from the enormous phyletic array that is available to us. It might be argued that the particular choices have served us well.
|
From page 216... ...
It is obvious that the particular assemblage of controlled and randomized environmental features may yield idiosyncratic results relative to another assemblage differing in some respect, and it follows that no single constellation of factors constituting the model can be regarded as definitive with respect to the target phenomenon. There is not, and cannot be, a "gold standard" an utterly valid single model that reflects all of the
|
From page 217... ...
Genetic Variables in the Total Model System The basic selection of the surrogate species for an animal model study is, of course, a selection based on genotype the differences among species in their gene pools. The genome of a species is fundamental in establishing the "theme" mentioned earlier, but among animals within the same species there exists enormous genetic variation that provides the variation on the theme.
|
From page 218... ...
These attributes confer on inbred strains a replicability so that the basic biological properties of the animal in the animal model can be assured in different laboratories and at different times (Festing, 1971; McClearn and Hofer, 1999a)
|
From page 219... ...
The logic of inbred strain comparisons is as follows: the animals of each strain are replicas of the same genotype; variability within strains is attributable to environmental sources; animals of different inbred strains have different genotypes; mean phenotypic differences between strains (reared and tested in the same environment) are attributable to these genetic differences between strains.
|
From page 220... ...
Until a sufficient body of data concerning live-trapped groups has accumulated and become a standard research resource, it is likely that genetically heterogeneous stocks will be obtained by mating of stocks and strains already abundantly available in laboratory colonies. Assembling heterogeneous stocks from the existing inbred strains has the problems of derivation from the clearly "abnormal" starting points but has the substantial advantage of a high degree of replicability.
|
From page 221... ...
One interpretation is that the heterozygosity of the Fit animals confers a higher degree of developmental homeostasis (see Phelan and Austad, 1994; McClearn and Hofer, 1999a, l999b; Miller et al., 1999~. As a consequence, Fit animals are sometimes recommended instead of inbred strains in studies requiring genetic uniformity of the subjects.
|
From page 222... ...
The linkage relationships will break down systematically as a function of number of generations, and obtained correlations among phenotypes will more assuredly be due to shared mechanisms causally downstream from the same gene or genes rather than fortuitous location of independent genes on the same chromosomes. In the QTL and mapping endeavors, different purposes are served by heterogeneous stocks in different stages of linkage disequilibrium.
|
From page 223... ...
The combination of genetic fixation and variability provided by recombinant inbred strains is proving itself of particular value in the current search for quantitative trait loci. Recombinant inbred (RI)
|
From page 224... ...
Perhaps more importantly, once generated, these selectively bred animals can serve as prime research material for the investigation of the mechanisms through which the genetic influences are mediated. Phenotypic selective breeding is an extremely effective method for manipulating entire blocks of anonymous genes, operating on all loci affecting the phenotype that are segregating in the foundation (necessarily heterogeneous)
|
From page 225... ...
Thus, genetic complexes of yet-anonymous genes can be built in various configurations based on mate assignment according to QTL genotypes, capable of generating, as in the case of phenotypic selection, animal models purpose-built to investigator specification. SUMMARY AND CONCLUSION In epidemiological and demographic research arenas, where genes and biological markers can be sought directly in human populations as well as animal models, the utility of research on animals lies in, among other attributes, their shorter lifetimes, shorter generation intervals, and accessibility for study of putative mechanisms.
|
From page 226... ...
The important phenomena addressed in this volume deserve optimal utilization of these tools. To this end, it should be remembered that the logic of animal model research requires efficient communication between the worlds of the animal modelers and the human population
|
From page 227... ...
Belknap, and K.J. Buck 1994 Genetic animal models of alcohol and drug abuse.
|
From page 228... ...
Phelan, J.P., and S.N. Austad 1994 Selecting animal models of human aging: Inbred strains often exhibit less biological uniformity than F1 hybrids.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.