The charge-state model of protein polymorphism in natural populations

1975 ◽  
Vol 6 (3) ◽  
pp. 149-163 ◽  
Author(s):  
D. R. Marshall ◽  
A. H. D. Brown
Keyword(s):  
Charge State ◽  
Natural Populations ◽  
State Model ◽  
Protein Polymorphism

scholarly journals Profiles of electrophoretic alleles in natural populations

1975 ◽  
Vol 25 (2) ◽  
pp. 137-143 ◽  
Author(s):  
A. H. D. Brown ◽  
D. R. Marshall ◽  
L. Albrecht
Keyword(s):  
Charge State ◽  
Frequency Distribution ◽  
Finite Population ◽  
Natural Populations ◽  
State Model ◽  
Geometric Series ◽  
Effective Number ◽  
Expected Frequency ◽  
Central Moments

SUMMARYThe charge state model of Ohta & Kimura (1973) for the number of electrophoretically detectable alleles in a finite population, is extended to include mutations of both one and two charge changes. The effective number of alleles (ne) is increased only slightly by this extension. Electrophoretic profiles of neutral variants are shown on average to be leptokurtic and have their odd central moments equal to zero. The expected frequency distribution of pairs of gametes which differ by 1,2,3,… charge units can be obtained as the sum of the appropriate terms from two geometric series.

scholarly journals TESTING FOR SELECTIVE NEUTRALITY OF ELECTROPHORETICALLY DETECTABLE PROTEIN POLYMORPHISMS

Genetics ◽  
1976 ◽  
Vol 84 (3) ◽  
pp. 639-659
Author(s):  
B S Weir ◽  
A H D Brown ◽  
D R Marshall
Keyword(s):  
Charge State ◽  
Neutral Theory ◽  
Natural Populations ◽  
State Model ◽  
Model Parameters ◽  
Simulation Data ◽  
Chi Square ◽  
Electrophoretic Mobilities ◽  
Selective Neutrality ◽  
Protein Polymorphisms

ABSTRACT The statistical assessment of gene-frequency data on protein polymorphisms in natural populations remains a contentious issue. Here we formulate a test of whether polymorphisms detected by electrophoresis are in accordance with the stepwise, or charge-state, model of mutation in finite populations in the absence of selection. First, estimates of the model parameters are derived by minimizing chi-square deviations of the observed frequencies of genotypes with alleles (0,1,2…) units apart from their theoretical expected values. Then the remaining deviation is tested under the null hypothesis of neutrality. The procedure was found to be conservative for false rejections in simulation data. We applied the test to Ayala and Tracey 's data on 27 allozymic loci in six populations of Drosophila willistoni. About one-quarter of polymorphic loci showed significant departure from the neutral theory predictions in virtually all populations. A further quarter showed significant departure in some populations. The remaining data showed an acceptable fit to the charge state model. A predominating mode of selection was selection against alleles associated with extreme electrophoretic mobilities. The advantageous properties and the difficulties of the procedure are discussed.

Evidence against the negative-charge-state model for theDXcenter inn-type GaAs

1989 ◽  
Vol 62 (16) ◽  
pp. 1922-1922 ◽  
Author(s):  
D. K. Maude ◽  
L. Eaves ◽  
T. J. Foster ◽  
J. C. Portal
Keyword(s):  
Charge State ◽  
Negative Charge ◽  
State Model

scholarly journals Tungsten divertor plasma simulation with bundled charge state model by SOLPS-ITER on EAST

AIP Advances ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 025233
Author(s):  
Shanlu Gao ◽  
Xiaoju Liu ◽  
Guozhong Deng ◽  
Tingfeng Ming ◽  
Guoqiang Li ◽  
...  
Keyword(s):  
Charge State ◽  
State Model ◽  
Plasma Simulation

scholarly journals STATISTICAL STUDIES ON PROTEIN POLYMORPHISM IN NATURAL POPULATIONS. III. DISTRIBUTION OF ALLELE FREQUENCIES AND THE NUMBER OF ALLELES PER LOCUS

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 1039-1063
Author(s):  
Ranajit Chakraborty ◽  
Paul A Fuerst ◽  
Masatoshi Nei
Keyword(s):  
Molecular Weight ◽  
Allele Frequency ◽  
Frequency Distribution ◽  
Gene Frequency ◽  
Natural Populations ◽  
Allele Frequencies ◽  
Protein Polymorphism ◽  
Allele Frequency Distribution ◽  
Wide Range ◽  
Rare Alleles

ABSTRACT With the aim of understanding the mechanism of maintenance of protein polymorphism, we have studied the properties of allele frequency distribution and the number of alleles per locus, using gene-frequency data from a wide range of organisms (mammals, birds, reptiles, amphibians, Drosophila and non-Drosophila invertebrates) in which 20 or more loci with at least 100 genes were sampled. The observed distribution of allele frequencies was U-shaped in all of the 138 populations (mostly species or subspecies) examined and generally agreed with the theoretical distribution expected under the mutation-drift hypothesis, though there was a significant excess of rare alleles (gene frequency, 0 ~ 0.05) in about a quarter of the populations. The agreement between the mutation-drift theory and observed data was quite satisfactory for the numbers of polymorphic (gene frequency, 0.05 ~ 0.95) and monomorphic (0.95 ~ 1.O) alleles.—The observed pattern of allele-frequency distribution was incompatible with the prediction from the overdominance hypothesis. The observed correlations of the numbers of rare alleles, polymorphic alleles and monomorphic alleles with heterozygosity were of the order of magnitude that was expected under the mutation-drift hypothesis. Our results did not support the view that intracistronic recombination is an important source of genetic variation. The total number of alleles per locus was positively correlated with molecular weight in most of the species examined, and the magnitude of the correlation was consistent with the theoretical prediction from mutation-drift hypothesis. The correlation between molecular weight and the number of alleles was generally higher than the correlation between molecular weight and heterozygosity, as expected.

scholarly journals POPULATION DIFFERENTIATION UNDER THE CHARGE STATE MODEL

Genetics ◽  
1975 ◽  
Vol 81 (4) ◽  
pp. 739-748
Author(s):  
A H D Brown ◽  
D R Marshall ◽  
B S Weir
Keyword(s):  
Natural Selection ◽  
Charge State ◽  
Migration Rate ◽  
Balancing Selection ◽  
State Model ◽  
Published Data ◽  
Island Population ◽  
Island Populations ◽  
Migration Rates ◽  
Protein Variants

ABSTRACT The extent of divergence between partially isolated sub-populations for electrophoretically detectable alleles was formulated assuming the island model of migration and the charge state model of mutation. At equilibrium the ratio of the variance of charge between the means of k different islands to the average within-island variance of charge was shown to be approximately 4Nemk  2/(k-1)2 where Ne is the effective size of each island population and m is the migration rate. This ratio was calculated from published data for eight polymorphic loci in six island populations of Drosophila willistoni . Under the assumption that all variants are selectively neutral, migration rates of greater than 10 adults per generation per island are required to explain the observed similarity of the allelic profiles in D. willistoni . Since the islands studied appear to be virtually completely isolated it was concluded either that the observed protein variants are adaptive and maintained in populations by some form of balancing selection or that the observed variants themselves are neutral but natural selection acts to restrict the appearance of more extreme variants in the charge carried.

scholarly journals A TAXONOMIC APPROACH TO EVALUATION OF THE CHARGE STATE MODEL USING TWELVE SPECIES OF SEA ANEMONE

Genetics ◽  
1983 ◽  
Vol 103 (4) ◽  
pp. 741-752
Author(s):  
Steven A McCommas
Keyword(s):  
Genetic Distance ◽  
Charge State ◽  
Sea Anemone ◽  
State Model ◽  
Apparent Difference ◽  
Closely Related Species ◽  
Linear Distance ◽  
Polymorphic Species ◽  
Taxonomic Approach ◽  
Generally True

ABSTRACT The charge-state model of electrophoretic variation was tested by comparing the distances between nearest electromorphs of five enzyme loci within polymorphic species and among pooled species of sea anemone. If the charge-state model is generally true, and in particular if it allows linear distance between electromorphs to be used as a measure of genetic distance, then electromorphs of different species should be on the same "mobility ladder". Therefore, distances between adjacent electromorphs should be approximately equal for the two sets of comparisons. It was found that distances between adjacent electromorphs for each locus were significantly smaller for the pooled comparisons than within polymorphic species. Thus, it was concluded that much of the variation detected among different species does not conform to the charge-state model, and therefore that distance between electromorphs per se would not be a good measure of genetic distance. However, the charge-state model does appear to adequately account for most of the variation existing as common polymorphisms within species, or between very closely related species. Possible reasons for this apparent difference in the nature of the variation seen within and among species are discussed.

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