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Biomedical subjects

M J Wade

Publications and source records attributed to M J Wade.

At least 55 records · Page 3Linked to original sources
PubMed1982

Evolution of interference competition by individual, family, and group selection.

The necessary conditions for the evolution of social behaviors in a population with three levels of biological organization are derived by using a population genetic model (one locus, two alleles, random mating, discrete generations). Total selection on the behavior, Deltaq, is partitioned into the sum of three components: (i) Deltaq(I), selection between individuals within families; (ii) Deltaq(F), selection between families within groups; and (iii) Deltaq(G), selection between groups of families. I show that any level of selection can be made to operate in concert with or in opposition to any other, depending upon the fitness effects of the behavior. The implications of the model are discussed in relation to those adaptive explanations of phenotypic traits that generally consider selection to operate only between individuals.

Journal Article↗
PubMed1981

Geographic and genetic variation in death-feigning behavior in the flour beetle, Tribolium castaneum.

Five recently collected wild strains of the flour beetle, Tribolium castaneum, from Spain, Japan, and the United States were tested for phenotypic differences in the proclivity toward death feigning and in the duration of feints. Subsequently, the genetic basis for the observed geographic differences was established by within-strain and between-strain reciprocal crosses of the two most divergent strains. The results indicate that simple additive genetic factors are involved in the transmission of this behavior, with no detectable differences between sexes or evidence of maternal effects.

Animals↗
PubMed1979

Mutagenic action of a series of epoxides.

The mutagenicity of a series of 13 epoxide compounds was studied using a bacterial plate assay system. The histidine-dependent tester strains TA98 (for frameshift mutagens) and TA100 (for base-pair substitution mutagens) of Salmonella typhimurium were used. Mutagenicity was evaluated both with and without the additon of rat liver microsomal extract. Dieldrin, diglycidyl ether of bis phenol A and 3 of its homologues were not mutagenic. Allyl glycidyl ether, n-butyl glycidyl ether, vinly cyclohexene diepoxide, glycidol, glycidal-dehyde, diglycidyl ether, diepoxybutane and diglycidyl ether of substituted glycerine were mutagenic in the TA100 strain, causing reversion of the bacteria to histidine independence. Dose-reponse curves of the mutagenicity of the latter 4 compounds were obtained. On a molar basis, glycidaldehyde was about 20-50 times more potent in producing mutation that were the other 3 epoxides in the dose-response test. In general, the mutagenicity of the epoxides was not enhanced or diminished by the addition of microsomal extract.

Drug Evaluation, Preclinical↗
PubMed1978

Kin selection: A classical approach and a general solution.

The necessary conditions for the spread of genes that determine social behaviors and the rate of spread of these genes are derived for a simple model (single locus, two alleles, random mating, discrete generations) by using the classical population genetics approach pioneered by Haldane and the linear fitness function used previously by D. S. Wilson. These results are derived for social behaviors that are manifested by individuals within families, within pairs of families, or within groups of k families, for both diploid and haplodiploid organisms. I show that, when the groups of socially interacting individuals consist of the members of more than one family, severe restrictions are placed on the evolution of altruistic and social behaviors. Specifically, in these instances, the necessary conditions for the evolution of social behaviors are more stringent and the rate of evolution is greatly reduced.

Journal Article↗
PubMed1978

Group selection on a quantitative character.

We derive a model of group and individual selection on a quantitative character that is similar to the single-locus "metapopulation" models of group selection. Two alternative methods for the colonization of new or vacant habitats are examined and their effects are contrasted. In one model, all populations contribute migrants to a common pool, the "migrant pool," from which colonists are drawn at random to fill vacant sites. In the migrant pool there is complete mixing of individuals from different populations. This model of colonization is the one used in all previous models of group selection. In the other model, the "propagule pool" model, each propagule is made up of individuals derived from a single population and there is no mixing of colonists from different populations during propagule formation. The analysis shows that much more between-population genetic variance can be maintained with the propagule pool model than with the migrant pool model. Consequently, group selection can be much more effective in natural populations than is commonly supposed.

Journal Article↗
PubMed1978

Device for quantitative cytochemistry: a computerized scanning microdensitometer 'grain counter'.

A computerized scanning microdensitometer and autoradiographic grain counter was able to provide quantitative data on the cytochemical final reaction product formed within a single cell and also quantitate the kinetics of its formation. Optical density and area measurements were performed on hundreds of leukocytes from slides previously stained to demonstrate any one of a variety of reactions. These included cellular glycogen, lipids, peroxidase, esterases, alkaline phosphatase, and acid phosphatase. In addition to these slide studies, chamber studies with an adapted Dvorak-Stotler Chamber allowed the measurement of enzyme kinetics within single cells.

Autoradiography↗
PubMed1976

Group selections among laboratory populations of Tribolium.

Selection at the population level or group selection is defined as genetic change that is brought about or maintained by the differential extinction and/or proliferation of populations. Group selection for both increased and decreased adult population size was carried out among laboratory populations of Tribolium castaneum at 37-day intervals. The effect of individual selection within populations on adult population size was evaluated in an additional control series of populations. The response in the group selection treatments occurred rapidly, within three or four generations, and was large in magnitude, at times differing from the controls by over 200%. This response to selection at the populational level occurred despite strong individual selection which caused a decline in the mean size of the control populations from over 200 adults to near 50 adults in nine 37-day intervals. "Assay" experiments indicated that selective changes in fecundity, developmental time, body weight, and cannibalism rates were responsible in part for the observed treatment differences in adult population size. These findings have implications in terms of speciation in organisms whose range is composed of many partially isolated local populations.

Animals↗
PubMedDate not supplied

Studies of in vitro asbestos-cell interaction.

Using amosite and chrysotile, asbestos cytotoxicity is shown to be a function of time and is abolished by filtration of the culture medium containing asbestos fibers through a 0.2-micrometer filter. There is evidence that cytotoxicity is related to the phagocytic property of cells since non-phagocytic fibroblasts survive under conditions lethal to P388D1 cells. Time lapse studies show that apparently normal mitosis occurs in the presence of intracellular asbestos, but the presence of fibers in sufficient quantity results in cytotoxicity. Effects on human (WI-38) fibroblasts are also reported.

Animals↗
PubMedDate not supplied

Biological activity in vitro of chrysotile compared to its quarried parent rock (platy serpentine).

Crushed serpentine rock, quarried at Rockville, Maryland, has been used in large quantities for road and playground surfacing. The rock consists essentially of the fibrous serpentine mineral chrysotile (asbestos) and platy serpentines. In vitro bioassay in P338D1, a malignant mouse macrophage-like cell line, show that chrysotile is cytotoxic while the platy serpentines are not.

Animals↗