The Estimation of Gene Frequencies in a Random‐mating Population

Ceppellini, R; Siniscalco, M.; Smith, Cedric A. B.

doi:10.1111/j.1469-1809.1955.tb01360.x

Cited by 288 publications

(116 citation statements)

References 7 publications

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“…Estimation of the three independent parameters, t, p, and q, is performed using the two-step procedure of Clegget al (1978). The first step estimates the maternal genotype frequencies using the gene counting method of Ceppellini et al (1955) based on provisional estimates of s, t, p, q, and r, and then new estimates of these parameters are obtained by the method of maximum likelihood using Fisher's scoring method. The steps are repeated until convergence is achieved for all parameter estimates at both steps.…”

Section: Floral Variation and Mating Systemmentioning

confidence: 99%

VARIATION AND EVOLUTION OF BREEDING SYSTEMS IN THETURNERA ULMIFOLIAL. COMPLEX (TURNERACEAE)

1987

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Abstract. -The evolutionary and functional relationships among breeding systems and floral morphology were investigated in the Turnera ulmifolia complex. Predictions of a model of breeding system evolution among distylous and homostylous varieties were tested. Chromosome counts of 73 accessions revealed an association between breeding system and chromosome number. Diploid and tetraploid populations of five taxonomic varieties are distylous and self-incompatible, whereas hexaploid populations of three varieties are homostylous and self-compatible, The latter occur at different margins of the geographical range ofthe complex. Crossing studies and analyses of pollen and ovule fertility in F,'s revealed that the three homostylous varieties are intersterile.To test the prediction that,homostylous varieties are long homostyles that have originated by crossing over within the distyly supergene, a crossing program was undertaken among distylous and homostylous plants. Residual incompatibility was observed in styles and pollen of each homostylous variety with patterns consistent with predictions of the cross-over model. The intersterility of hexaploid varieties suggests that long homostyly has arisen on at least three occasions in the complex by recombination within the supergene controlling distyly. Deviation from expected compatibility behavior occurs in populations ofvar. angustifolia that have the longest styles. These phenotypes displayed the greatest separation between anthers and stigmas (herkogamy) and set little seed in crosses with long-or short-styled plants. This suggests that they are derived from long homostyles with shorter length styles. It is proposed that selection for increased outcrossing has favored the evolution of herkogamy in long homostyles.Estimates of outcrossing rate in a distylous population using allozyme markers confirmed that dimorphic incompatibility enforces complete outcrossing. Significant genetic variation for floral traits likely to influence the mating system, such as stigma-anther separation, occurs within and among homostylous populations ofvar. angustifolia on Jamaica. Estimates of the mating system of families from a population with varying degrees of stigma-anther separation, using five isozyme loci, were heterogeneous and ranged from t = 0.04-0.79. Families exhibiting the largest mean stigma-anther separation have higher outcrossing rates than those with little separation.

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Section: Floral Variation and Mating Systemmentioning

confidence: 99%

VARIATION AND EVOLUTION OF BREEDING SYSTEMS IN THETURNERA ULMIFOLIAL. COMPLEX (TURNERACEAE)

1987

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“…Haplotypes were assigned to this sample set using an automated program using an expectation-maximization algorithm. 10,11 The common polymorphisms used to designate haplotypes included: 18,202C-ϾT; 31,385delT; 34,268A-ϾG (Q356R); 35,278G-ϾA (D693N); 35,283C-ϾT (S694S); 35,512T-ϾC (L771L); 35,813C-ϾT (P871L); 36,314A-ϾG (E1038G); 36,320G-ϾA (S1040N); 36,749A-ϾG (K1183R); 37,240A-ϾG (R1347G); 46,278T-ϾC (S1436S); 57,655A-ϾG (S1613G); 57,774G-ϾA (M1652I). Unless otherwise indicated all numeric base designations throughout this report conform to GenBank accession L78833.…”

Section: Haplotype Analysismentioning

confidence: 99%

A Multi-Exonic BRCA1 Deletion Identified in Multiple Families through Single Nucleotide Polymorphism Haplotype Pair Analysis and Gene Amplification with Widely Dispersed Primer Sets

Hendrickson

Judkins

Deffenbaugh

et al. 2005

The Journal of Molecular Diagnostics

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The identification of intragenic rearrangements is important for a comprehensive understanding of mutations that occur in some clinically important genes. Single nucleotide polymorphism haplotypes obtained from clinical sequence data have been used to identify patients at high risk for rearrangement mutations. Application of this method identified a novel 26-kb deletion of BRCA1 exons 14 through 20 in patients from multiple families with hereditary breast and ovarian cancer. Clinical sequence data from 5911 anonymous patients were screened for genotypes that were inconsistent with known pairs of canonical haplotypes in BRCA1 that could be explained by hemizygous deletions involving exon 16. Long-range polymerase chain reaction demonstrated that two of six samples identified by this search contained a deletion in the expected region encompassing exons 14 through 20. The breakpoint was fully characterized by DNA sequencing and demonstrated that the deletion resulted from Alu-mediated recombination. This mutation was also identified twice in a set of 982 anonymous specimens that had negative clinical test results , but uninformative haplotypes. Three additional occurrences of this mutation were found by testing 10 other patients with the indicative genotype. An assay for this mutation was added to a comprehensive clinical breast/ovarian cancer test and eight more instances were found in 20 ,649 probands. This multiexon deletion has therefore been detected in 15 different North American families with hereditary breast/ovarian cancer. In conclusion , this primarily computational approach is highly effective and identifies specimens using existing data that are enriched for deletion mutations. Deleterious mutations in two tumor suppressor genes, BRCA1 and BRCA2, confer high risk for breast and/or ovarian cancer and are responsible for the majority of hereditary families. Recently, comprehensive clinical DNA sequencing revealed deleterious mutations in BRCA1 or BRCA2 in 17.2% of 10,000 patients. Women with a history of breast cancer or ovarian cancer had deleterious mutation rates of 20% and 34%, respectively. 1 The discovery of large genomic rearrangements within BRCA1 may partially explain the apparent discrepancy between expected mutation frequency and practical clinical sensitivity because existing clinical protocols using polymerase chain reaction (PCR)-based techniques designed to scan coding regions generally cannot detect these mutations. 2,3 The population distributions of rearrangement mutations mirror those of point mutations where some, such as the duplication of exon 13, are highly prevalent, whereas others appear restricted to certain ethnic groups or limited to single families. [3][4][5] Because both genes exhibit mutations distributed throughout their coding regions, clinical genetic tests have focused on mutation scanning encompassing their entire open reading frames. This approach has generated substantial data on the genetic variation within the coding regions of these genes (Breast Cancer Informatio...

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“…(i) In L. aurora, the frequencies of the four chromosomal arrangements UGP, Ug, uGP and ug have been estimated for each population using the iterative process of "gene counting" which is applicable (as here) to chromosome counting (Ceppellini, Siniscalco and Smith, 1955;Smith 1956). The calculation is a very long one, so the Ibadan University IBM computer was programmed to carry it out.…”

Section: F Barkermentioning

confidence: 99%

Polymorphism in West African snails

Barker

1968

Heredity

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The Estimation of Gene Frequencies in a Random‐mating Population

Cited by 288 publications

References 7 publications

VARIATION AND EVOLUTION OF BREEDING SYSTEMS IN THETURNERA ULMIFOLIAL. COMPLEX (TURNERACEAE)

VARIATION AND EVOLUTION OF BREEDING SYSTEMS IN THETURNERA ULMIFOLIAL. COMPLEX (TURNERACEAE)

A Multi-Exonic BRCA1 Deletion Identified in Multiple Families through Single Nucleotide Polymorphism Haplotype Pair Analysis and Gene Amplification with Widely Dispersed Primer Sets

Polymorphism in West African snails

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