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At least 325 records · Page 18Linked to original sources
PubMed2000

The character or the variation: the genetic analysis of the insecticide-resistance phenotype.

In this critique it is argued that the genetic basis of the evolution of resistance is dependent on how the phenotypic, and underlying genotypic, variation is channelled during a selective response. A polygenic response is preferentially favoured if selection acts within the phenotypic distribution of susceptibles; a monogenic response is predicted if selection screens rare mutations with phenotypes outside that susceptible distribution. The relevance of this model to the method of genetic analysis, the prediction of resistance mechanisms to novel insecticides, the generation of resistant beneficial insects and the development of the most effective resistance and integrated pest management programmes is discussed.

Animals↗
PubMed1999

Genetic analysis of leaf form mutants from the Arabidopsis Information Service collection.

Although a vast inventory of morphological mutants of Arabidopsis thaliana is available, only some have been used for genetic studies of leaf development. Such is the case with the Arabidopsis Information Service (AIS) Form Mutants collection, assembled by A. R. Kranz and currently stored at the Nottingham Arabidopsis Stock Centre, which includes a large number of mutant lines, most of which have been little studied. With the aim of contributing to the genetic dissection of leaf ontogeny, we have subjected 57 mutant lines isolated by others to genetic analysis; 47 of which were from the AIS collection. These are characterized by vegetative leaves of abnormal shape or size, and were chosen as candidates for mutations in genes required for leaf morphogenesis. The mutant phenotypes studied were shown to be inherited as single recessive Mendelian traits and were classified into 10 phenotypic classes. These mutant strains were found to fall into 37 complementation groups, 7 of which corresponded to known genes. Results of the phenotypic analysis and data on the genetic interactions of these mutants are presented, and their possible developmental defects discussed.

Arabidopsis↗
PubMed1996

Genetic analysis of second primary lung cancers in patients surviving small cell lung cancer.

We performed genetic analysis on 12 second primary non-small cell lung cancers in patients surviving small cell lung cancer to assess the potential contribution of smoking to the development of these tumors. Mutations of TP53 were found in three (25%) tumors, KRAS2 in three (25%) tumors, and CDKN2 in two (18%) tumors. Four (50%) mutations (one each in TP53 and CDKN2 and two in KRAS2) were G:C to T:A transversions on the coding strand, a mutation accounting for approximately one-third of mutations in smoking-related tumors but uncommonly found in lung cancers not associated with smoking. The genetic changes in these second lung cancers are more representative of smoking-associated malignancies than lung cancers arising in patients occupationally exposed to irradiation and atomic bomb survivors.

Carcinoma, Small Cell↗
PubMed1976

The effect of caffeine on repair systems in oocytes of Drosophila melanogaster. III. Genetic analysis of factors controlling maternal repair in a repair-deficient strain of Drosophila melanogaster.

Genetic analysis was performed to locate the factors involved in the defective repair mechanism in the oocytes of Ubx e4/Payne ca females. The results demonstrate that at least three third-chromosome factors may be involved in the control of maternal repair, the two most effective ones being located on the right arm of the third chromosome, one near the Ubx locus and the other near the ca locus.

Animals↗
PubMed2006

A new era in the genetic analysis of multiple sclerosis.

PURPOSE OF REVIEW: This review covers the latest developments in the genetic analysis of multiple sclerosis in the context of advancing knowledge about the nature of complex disease. This year has seen rapid progress dominated by early applications of high-throughput single-nucleotide polymorphism typing technology. RECENT FINDINGS: The last 12 months have seen the completion of what is probably a definitive screen for linkage, together with the beginnings of indirect full-genome screens for association with common variants. Alongside this the first ever systematic admixture mapping effort has also been completed, suggesting a possible explanation for the apparent excess of the condition in Europeans and implicating a novel susceptibility locus on chromosome 1. SUMMARY: It is now clear that association-based studies in large cohorts will be needed to unravel the genetic basis of susceptibility to multiple sclerosis. Importantly it is also clear that the necessary tools have now arrived and that the next few years are likely to see exciting developments.

Genetic Linkage↗
PubMed2006

Genetic analysis and fine mapping of a rice brown planthopper (Nilaparvata lugens Stål) resistance gene bph19(t).

Genetic analysis and fine mapping of a resistance gene against brown planthopper (BPH) biotype 2 in rice was performed using two F(2) populations derived from two crosses between a resistant indica cultivar (cv.), AS20-1, and two susceptible japonica cvs., Aichi Asahi and Lijiangxintuanheigu. Insect resistance was evaluated using F(1) plants and the two F(2) populations. The results showed that a single recessive gene, tentatively designated as bph19(t), conditioned the resistance in AS20-1. A linkage analysis, mainly employing microsatellite markers, was carried out in the two F(2) populations through bulked segregant analysis and recessive class analysis (RCA), in combination with bioinformatics analysis (BIA). The resistance gene locus bph19(t) was finely mapped to a region of about 1.0 cM on the short arm of chromosome 3, flanked by markers RM6308 and RM3134, where one known marker RM1022, and four new markers, b1, b2, b3 and b4, developed in the present study were co-segregating with the locus. To physically map this locus, the bph19(t)-linked markers were landed on bacterial artificial chromosome or P1 artificial chromosome clones of the reference cv., Nipponbare, released by the International Rice Genome Sequencing Project. Sequence information of these clones was used to construct a physical map of the bph19(t) locus, in silico, by BIA. The bph19(t) locus was physically defined to an interval of about 60 kb. The detailed genetic and physical maps of the bph19(t) locus will facilitate marker-assisted gene pyramiding and cloning.

Animals↗
PubMed1990

Genetic analysis of differences in behavioral reactivity to neonatal injection of testosterone in female mice.

A genetic analysis of differences in reactivity to early exposure of female BALB/cBy and C57BL/6By mice to testosterone was performed using the C x B recombinant-inbred (RI) strains. RI female mice were given a single injection of 1 mg of testosterone propionate on day 4 of life and observed in adulthood in the presence of a male attempting to mate. The latency of the first attack, the number of attacks per minute, the incidence of attack, and tail-rattling were recorded. The strain distribution patterns of the RI strains for all variables is consistent with polygenic correlate of reactivity to neonatal androgenization and is concordant with the heterotic inheritance effect observed in F1's for the latency of the first attack and the number of attacks per minute. The RI strain distribution pattern shows that the genetic correlates of reactivity to early testosterone exposure differ according to the variable studied.

Aggression↗
PubMed2003

A quantitative trait locus influencing free plasma protein S levels on human chromosome 1q: results from the Genetic Analysis of Idiopathic Thrombophilia (GAIT) project.

OBJECTIVE: Protein S (PS) is a component of the protein C anticoagulant system. PS deficiency is associated with myocardial infarction and venous thromboembolism, two highly prevalent causes of death in industrialized nations. As part of the Genetic Analysis of Idiopathic Thrombophilia (GAIT) project, we conducted a genome-wide linkage screen to localize genes influencing variation in free PS (fPS) plasma levels. METHODS AND RESULTS: fPS levels were measured in 397 individuals in 21 Spanish families. A total of 363 highly informative microsatellite markers were genotyped to provide a 10-cM genetic map, and variance component linkage methods were used. A region on chromosome 1q32, flanked by markers D1S425 and D1S213, showed strong evidence of linkage with fPS levels (LOD score, 4.07; nominal P=7.5x10(-6); genome-wide P=0.0024). This region contains two positional candidate genes, the complement component 4-binding protein alpha and beta chains, which encode the principal binding protein for PS. Suggestive evidence for linkage was also observed on chromosomes 11p and 19p. CONCLUSIONS: These results represent one of the first genomic screens for quantitative variation in a component of the hemostatic pathway and provide strong evidence for a locus on chromosome 1q influencing fPS levels.

Adolescent↗
PubMed2001

Phenotypes and genetic analysis of psychiatric and neuropsychiatric traits.

A workshop was held at Rockefeller University entitled "Phenotypes and Genetic Analysis of Complex Traits." The purpose of the workshop was to examine phenotype definition for complex traits, in particular, psychiatric and neuropsychiatric traits. An additional goal of the workshop was to examine statistical genetic approaches that specifically address the oligogenic nature of psychiatric traits. An overview of topics that were addressed and discussed at the workshop is presented in this article.

Animals↗
PubMed1980

Genetical analysis of a sterile mutant by protoplast fusion in the fission yeast Schizosaccharomyces pombe.

The genetical analysis, by protoplast fusion, of the sterile strain ED22 of Schizosaccharomyces pombe is described. Two major mutations are harboured by this strain. One, cdc 25.22, is conditionally defective in mitosis. The other mutation, ste 1.1, causes sterility in strains of h-, h+ or mat 2.102 mating-type. Sterility is due to the failure of cell agglutination. We present evidence that ste 1.1 is defective in the production of a non-diffusible and non-mating-type specific factor. ste 1 and cdc 25 both map on chromosome I and are loosely linked.

Agglutination↗
PubMed1998

Correlation of histologic morphology and tumor stage with molecular genetic analysis using microdissection in gastric carcinomas.

Precise correlation of histomorphology with the results of molecular genetic analysis is difficult in gastric cancer tissue composed of intestinal and diffuse types. A novel microdissection procedure was applied to correlate p53 and APC allelic loss with histologic type and tumor stage (mucosal vs. invasive cancer) in formalin-fixed, paraffin-embedded specimens of 25 gastric cancers. In addition, mucosal and invasive lesions were dissected from each of 11 invasive gastric cancers to study progression, and allelic loss of the p53 and APC genes was assessed. The p53 gene underwent loss of heterozygosity (LOH) in 4 of 4 informative cases of intestinal-type gastric cancer with mucosal lesions associated with invasion. By contrast, no p53 LOH was found among 6 informative cases with mucosal cancer. LOH of the APC gene in both intestinal and diffuse types of cancer was detected in 4 of 7 and 5 of 6 informative cases, respectively. These data suggest that allelic deletion of the p53 gene in intestinal-type gastric carcinoma predicts the invasive potential of mucosal cancer, and that inactivation of the APC gene plays a role in the genetic tumorigenesis of both intestinal and diffuse types of gastric cancer. Microdissection can correlate genetic alterations with histologic morphology in gastric cancer.

Adenocarcinoma↗
PubMed2005

Microfluidic genetic analysis with an integrated a-Si:H detector.

We have developed an integrated hydrogenated amorphous silicon (a-Si:H) fluorescence detector for microfluidic genetic analysis. It consists of a half-ball lens, a ZnS/YF3 multilayer optical interference filter with a pinhole, and an annular a-Si:H PIN photodiode allowing the laser excitation to pass up through the central aperture in the photodiode and the filter. Microfluidic separations of multiplex PCR products generated from methicillin-resistant/sensitive Staphylococcus aureus (MRSA/MSSA) DNA on microfluidic capillary electrophoresis (CE) devices are successfully detected with the integrated detector. Similarly, multiplex PCR amplicons from the kanamycin resistant and K12 serotype-specific genes of E. coli cells are detected. The direct detection of multiplex PCR amplicons indicates that the fluorescence detector can be successfully coupled with current microfluidic PCR-CE platforms. This work establishes that the integrated a-Si:H detector provides relevant limits of detection for point-of-care genetic and pathogen analysis with microfluidic devices.

DNA, Bacterial↗
PubMed2002

Pitfalls of genetic analysis using a doubled-haploid backcrossed to its parent.

A population derived from a doubled-haploid backcrossed to its parent has a unique genetic structure, which affects the mapping and genetic analysis of molecular-marker data. In such a cross: (1) repulsion linkages are reduced dramatically and can be detected only in restricted chromosome sections; each repulsion-linkage group represents a section of a chromosome carrying a crossover that occurred in the meiosis that produced the gamete from which the doubled-haploid was derived; (2) the number of coupling-linkage groups observed depends on how many crossovers occurred during the meiosis; the observed size of a linkage group will be only a fraction of a total chromosome if the chromosome carried in the doubled-haploid resulted from crossover exchanges; (3) the size covered by all the observed linkages is only equivalent to the haploid genome; and (4) the ratio of single-dose to multi-dose markers is inflated. These features have not been recognized in previous reports, resulting in misinterpretations in genetic mapping and analysis of the molecular-marker data. The ratio of single- to multi-dose markers has been used inappropriately to distinguish polyploid type.

Journal Article↗
PubMed2003

Genetic Analysis Workshop 13: simulated longitudinal data on families for a system of oligogenic traits.

The Genetic Analysis Workshop 13 simulated data aimed to mimic the major features of the real Framingham Heart Study data that formed Problem 1, but under a known inheritance model and with 100 replicates, so as to allow evaluation of the statistical properties of various methods. The pedigrees used were the 330 real pedigree structures (comprising 4692 individuals) with some minor changes to protect confidentiality. Fifty trait genes and 399 microsatellite markers were simulated by gene dropping on 22 autosomal chromosomes. Assuming random ascertainment of families, a system of eight longitudinal quantitative traits (designed to be similar to those in the real data) was generated with a wide range of heritabilities, including some pleiotropic and interactive effects. Genes could affect either the baseline level or the rate of change of the phenotype. Hypertension diagnosis and treatment were simulated with treatment availability, compliance, and efficacy depending on calendar year. Nongenetic traits of smoking and alcohol were generated as covariates for other traits. Death was simulated as a hazard rate depending upon age, sex, smoking, cholesterol, and systolic blood pressure. After the complete data were simulated, missing data indicators were generated based on logistic models fitted to the real data, involving the subject's history of previous missing values, together with that of their spouses, parents, siblings, and offspring, as well as marital status, only-child indicators, current value at certain simulated traits, and the data collection pattern on the cohort into which each subject was ascertained.

Adult↗
PubMed2000

Genetic analysis of the Utah population: a comparison of STR and VNTR loci.

Genetic data are reported for nine short tandem repeat (STR) loci (D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, and D7S820) and six variable number of tandem repeat (VNTR) loci (D2S44, D10S28, D4S139, D1S7, D5S110, and D17S79) in samples of Utah African Americans, European Americans, and Hispanics. Little evidence of departures from Hardy-Weinberg equilibrium or gametic equilibrium was found in these populations. Because of their relatively higher mutation rates, the VNTR loci exhibited higher average heterozygosity and lower FST levels than did the STR loci. Genetic distance analysis showed congruence between the two types of systems, and a genetic distance analysis of the STR data showed that the three Utah populations are genetically similar to the same ethnic groups in other parts of the United States. In addition, this analysis showed that the African American population is the most genetically divergent, with greater similarity between the Hispanic and European American populations. This analysis demonstrates a high degree of consistency for population designations commonly used in forensic analysis.

Evolution, Molecular↗
PubMed1995

Genetic analysis of tetracycline-resistant plasmids in enteropathogenic Escherichia coli isolated from patients in Nigeria.

Genetic analysis of antibiotic-resistant plasmids from 102 serologically defined strains of enteropathogenic Escherichia coli from Nigeria was carried out. All the isolates were screened for susceptibility to antibiotics, and 47 were found resistant to tetracycline. A total of 138 plasmids was isolated by agarose gel electrophoresis. Transformation and conjugation experiments showed that 57.4% of the resistant strains carried R-plasmids ranging in sizes from 2 to 46 x 10(6) daltons. Plasmid-determined resistance to tetracycline, ampicillin and streptomycin was found. Restriction endonuclease analysis of three of the commonest plasmids: p1679, p529 and p1479 revealed relatedness with respect to function and structure. The DNA segment on which TcR gene is located on each of them was identified by cloning into the vector plasmid pGL101. The recombinant plasmids pOADI and pOAD2 gave full expression of TcR gene when transformed into E. coli DHI. Furthermore, the tetracycline-resistant strains were examined for their phenotypic behaviour with respect to tetracycline and its lipophilic analogs.

Anti-Bacterial Agents↗
PubMed1987

Genetic analysis of serum lipid levels and blood pressure in a large kindred.

A 267-member Caucasian kindred with a high incidence of cardiovascular disease, originally from Evans County, Georgia, was chosen for genetic analysis of serum lipid levels and blood pressure. Total serum cholesterol, triglycerides, high density lipoprotein cholesterol (HDL), and systolic and diastolic blood pressures were natural logarithm transformed and then adjusted for significant age, sex, and behavioral trait effects. Major gene pedigree analysis was used to estimate genetic parameters and to test hypotheses about the mode of transmission of each trait. Multivariate methods were also used to estimate linear combinations of the variables that best fit genetic models. The data were consistent with a major gene segregating for high levels of triglycerides in this kindred. However, dominant and recessive hypotheses could not be distinguished. Although diastolic blood pressure fit a mixture of two distributions significantly better than a single normal, major gene hypotheses could be rejected while the no-transmission hypothesis could not. There was no evidence of a major gene effect on cholesterol, HDL, systolic blood pressure, or any of the hypothetical traits represented by linear functions of the physical-lipid traits.

Adult↗