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At least 181 records · Page 10Linked to original sources
PubMed1976

Two-sided assortative mating for a single locus.

Most models previously considered for assortative mating were such that no change in gene frequencies occurred, or that one-sided assortative mating was occurring. Two-sided assortative mating is more realistic for human populations, and in this paper a model of two-sided assortative mating is analysed for two autosomal alleles with dominance, an important case for human genetics. The concept of a relative probability of matin between two phenotypes is used, and this variable can take into account factors such as different propensities for assortment in the various phenotypes and so forth. It is shown that the gene frequency may vary from generation to generation and conditions for the establishment of a stable polymorphism are given. For instance, Stanton (1947) has considered a special case of two-sided assortative mating with two autosomal alleles and a constant correlation between mates, where the value expressed by the heterozygote is numerically exactly half-way between the values exhibited by the two homozygotes. Also he has considered a special form of assortative mating, where the probability of occurrence of matings between the same homozygotes has been increased in each generation by the same constant factor as the probability of occurrence of matings between different homozygotes has been decreased. The probability of occurrence of matings involving heterozygotes remains the same as if mating were random. For this particular model the frequency of the genotypes in those who mate in generation t is the same as for the general population in generation t, but the genotypic frequencies change from generation to generation, reaching an equilibrium value. Stark (1976) has also considered a similar model to Stanton's (1947), the major difference occurring in the construction of the mating frequencies, which in this case occurs according to the canonical decomposition of the 2-way table of mating frequencies. Stark shows the correspondence between the results for this model and those given by Malécot (1939, 1948). The results for all these models depend on the particular values assigned to the genotypes. Also these models could be extended as outlined in this article for the case of two autosomal alleles with dominance.

Alleles↗
PubMed1976

Limits of the general two-allele single locus model with incomplete penetrance.

A graphical method is presented that allows an investigator to find the mathematical limits of the general one locus two allele genetic model for any trait whose population prevalence is known. It is seen that while the model is quite flexible in its ability to fit family data, there remains a large area where the model cannot be fitted. Specific sub-regions corresponding to particular hypotheses (e.g. underdominant v. intermediate v. overdominant) can be found, thereby limiting the area that needs to be searched by other more complicated techniques. Moreover, knowledge of where a set of observations lies can enable an investigator to frame and test specific subhypotheses.

Alleles↗
PubMed1997

A single locus on human chromosome 21 directs the expression of a receptor for adenovirus type 2 in mouse A9 cells.

The receptors on human cells which mediate adsorption of adenoviruses have not been identified. We found that murine A9 cells and Chinese hamster ovary (CHO) cells failed to bind significant levels of radiolabeled adenovirus type 2 (Ad2) virions but that derivatives of these cells carrying human chromosome 21 exhibited high levels of virus binding that was specific for the viral fiber protein. G418-resistant A9 cell transformants expressing Ad2 receptors were detected at a frequency of about 10(-4) following cotransfection with high-molecular-weight DNAs from mouse cells containing human chromosome 21 and plasmid DNA containing a neomycin resistance gene. The Ad2 receptors on the transformed A9 cells were similar to those on human cells with respect to their concentration on the cell membrane, their affinity for the viral fiber protein, and their ability to direct virus into cells along a pathway leading to delivery of the viral DNA genome into the cell nucleus. Furthermore, identical human DNA fragments were present in three independent mouse cell transformants expressing Ad2 receptors, supporting the conclusion that these human DNA fragments correspond to a gene or locus on chromosome 21 that directs the expression of Ad2 receptors in these cells.

Adenoviruses, Human↗
PubMed1996

Characterization of a single-locus minisatellite DNA in Xenopus laevis.

We have cloned a minisatellite tandem array (XTA) from Xenopus laevis that contains approximately 200 copies of the 20-bp repeat 5'-CCAACAGCCTGCCCATCCAT-3'. The XTA sequence is present only once per haploid genome and is polymorphic with respect to repeat number and location of flanking restriction endonuclease sites. Although the 20-bp repeat has not previously been described, flanking sequences suggest that it lies proximal to coding regions in the Xenopus genome.

Animals↗
PubMed2004

D1S80 single-locus discrimination among African populations.

The highly polymorphic D1S80 locus has no known genetic function. However, this variable number of tandem repeats (VNTR) locus has been highly valuable in forensic identification. In this study we report the allele and genotype frequencies of five African populations (Benin, Cameroon, Egypt, Kenya, and Rwanda), which can be used as databases to help characterize populations and identify individuals. The allele frequencies were used to infer genetic associations through phylogenetic, principal component, and G test statistical analyses. Compliance with Hardy-Weinberg equilibrium expectations was determined as were F(ST) estimates, theta p values, and power of discrimination assessment for each population. Our analyses of 28 additional populations demonstrate that the D1S80 locus alone can be used to discriminate geographic and ethnic groups. We have generated databases useful for human identification and phylogenetic studies.

Africa↗
PubMed2004

Single-locus latitudinal clines and their relationship to temperate adaptation in metabolic genes and derived alleles in Drosophila melanogaster.

We report a study in Drosophila melanogaster of latitudinal clines for 23 SNPs embedded in 13 genes (Pgi, Gapdh1, UGPase, Pglym78, Pglym87, Eno, Men, Gdh, Sod, Pgk, Mdh1, TreS, Treh) representing various metabolic enzymes. Our samples are from 10 populations spanning latitude from southern Florida to northern Vermont. Three new clines with latitude were detected. These are the amino acid polymorphisms in the NAD-dependent glutamate dehydrogenase (Gdh) and trehalase (Treh) genes, and a silent site polymorphism in the UDP-glucose pyrophosphorylase gene (UGPase). The result, when combined with the overall incidence and pattern of reports for six other genes (Adh, Gpdh, Pgm, G6pd, 6Pgd, Hex-C), presents a picture of latitudinal clines in metabolic genes prevalent around the branch point of competing pathways. For six of the seven amino acid polymorphisms showing significant latitudinal clines in North America, the derived allele is the one increasing with latitude, suggesting temperate adaptation. This is consistent with a model of an Afrotropical ancestral species adapting to temperate climates through selection favoring new mutations.

Adaptation, Physiological↗
PubMed2005

[Analysis of a paternity case in which the alleged father was deceased: single locus mismatch].

We performed a paternity test without the alleged father, who was deceased, and we found a mismatch in one of the alleles of the autosomal short tandem repeat (STR) locus D3S1358 in the illegitimate daughter. DNA genotypes of the dead alleged father were estimated from the DNA genotypes of his wife and their four children. The ABO genotype, the DXS10011 locus and the calculations using the 12 STR loci and the D1S80 locus, but not the STR locus D3S1358 suggested that there was a high probability that the dead alleged father was in fact the actual biological father. The genotype of locus D3S1358 of the dead alleged father, the illegitimate daughter's mother and the illegitimate daughter was 15 / 17, 15 / 17 and 15 / 18, respectively. PCR and sequencing after TA cloning of allele 17 of one of the children who had only a homozygote of allele 17, of allele 17 of the illegitimate daughter's mother and of allele 18 of the illegitimate daughter revealed that allele 18 which was considered to be a mutated allele had one more repeat of (GATA) within the first repeat region.

ABO Blood-Group System↗