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At least 577 records · Page 32Linked to original sources
PubMed2003

Genetic analysis of spatial foraging patterns and resource sharing in bumble bee pollinators.

Conservation biologists, evolutionary ecologists and agricultural biologists require an improved understanding of how pollinators utilize space and share resources. Using microsatellite markers, we conducted a genetic analysis of space use and resource sharing at several spatial scales among workers of two ecologically dissimilar bumble bee species (Bombus terrestris and B. pascuorum) foraging in an urban landscape (London, UK). At fine scales, the relatedness of workers visiting small patches of flowers did not differ significantly from zero. Therefore, colonies shared flower patches randomly with other colonies, suggesting that worker scent-marks deterring visits to unrewarding flowers have not evolved as signals benefiting nestmates. To investigate space use at intermediate scales, we developed a program based on Thomas & Hill's maximum likelihood sibship reconstruction method to estimate the number of colonies utilizing single sites. The average number of colonies (95% confidence limits) sending workers to forage at sites of approximately 1 ha in area was 96 colonies (84-118) in B. terrestris and 66 colonies (61-76) in B. pascuorum. These values are surprisingly high and suggested that workers travelled far from their colonies to visit the sites. At the landscape scale, there was little or no genetic differentiation between sites. We conclude that urban habitats support large bumble bee populations and are potentially valuable in terms of bumble bee conservation. In addition, bumble bee-mediated gene flow in plants is likely to occur over large distances and plant-bumble bee conservation requires landscape-scale action.

Alleles↗
PubMed1987

Genetic analysis in Salmonella typhimurium with a small collection of randomly spaced insertions of transposon Tn10 delta 16 delta 17.

We report the isolation of a group of 279 Salmonella typhimurium strains carrying randomly spaced insertions of the minitransposon Tn10 delta 16 delta 17 and describe the use of these strains to facilitate genetic analysis. The insertions were isolated initially in individual recombinant lambda clones from a genomic library. Individual insertions were then moved into the S. typhimurium chromosome, where the distribution of insertion sites relative to standard genetic markers was analyzed in a series of transductional crosses. Since a different, randomly chosen clone was used to generate each insertion, the distribution of insertion positions should have been as random as the cloning events leading to the formation of the library. In agreement with this expectation, most S. typhimurium markers tested were cotransducible with one or more of these Tn10 delta 16 delta 17 insertions. We expect that most new mutations will be quickly classified and mapped by determination of the pattern of cotransduction with this set of insertions. This use is illustrated by the analysis of a group of lac operon fusions regulated by anaerobiosis. We also describe several other applications that should make this collection a useful new tool in S. typhimurium genetics.

Chromosome Mapping↗
PubMed1976

[Genetic analysis of open-field behavior in mice (author's transl)].

505 mice of BB and C 57 BL/6 as parental strains, as well as derived F 1, F 2 and backcrosses were tested for spontaneous motor activities and eliminations in 4 different apparatus. A component being highly associated expecially with open-field measures was obtained from the principal component analysis. This suggests that an individual score on this composite variable represents a certain unique open-field behavioral pattern. Relatively low heritabilities in broad sense (coefficient of genetic determination) were given by classic genetic analysis, indicating the substantially great effects of the environmental factors of this behavioral character. Further, albino mice in BB, F 2 and B X B showed a very inactive open-field behavioral pattern than pigmented mice.

Animals↗
PubMed1985

Quantitative genetic analysis of tumor progression.

Metastasis and resistance to chemotherapy are common features of progressed cancers. With respect to the latter phenotype, it is thought that during tumor growth drug-resistant cells arise spontaneously at rates characteristic of the genetic alterations involved. On application of chemotherapy, such variant tumor cells are more likely to survive, and they may eventually dominate, resulting in a non-responsive malignancy. Aspects of this model have been confirmed in a number of experimental systems and in patients. In contrast to our understanding of drug resistance, steps involved in the progression to metastatic spread of tumor cells are much less well-understood. In this review we describe methodologies of quantitative genetic analysis with reference to development of drug resistance. We then describe attempts by ourselves and others to use a similar approach to investigate metastatic properties. Based on these studies, we have proposed the quantitative 'dynamic heterogeneity' model of tumor metastasis, which is presented here. Using an 'experimental' metastasis assay and Luria-Delbruck fluctuation analysis, we determined that in murine KHT fibrosarcoma and B16 melanoma lines, 'metastatic' variants with a distinct phenotype are generated at high rates. These variants are relatively unstable resulting in a dynamic equilibrium between generation and loss of metastatic variants. The metastatic ability of such a tumor population is thus dependent on the frequency of a subpopulation of metastatic variants which are turning over rapidly. This dynamic heterogeneity model is able to quantitatively provide a unifying explanation for a wide range of observations concerning tumor heterogeneity and clonal instability. Genetic mechanisms involving rapid rates have been characterized in drug-resistant variants. We speculate that similar processes may be involved in different aspects of tumor progression such as those resulting in metastasis.

Animals↗
PubMed1984

Polyclonal IgE increase after HgCl2 injections in BN and LEW rats: a genetic analysis.

An autoimmune disease and a dramatic increase in total serum IgE concentration are observed in BN rats that are chronically injected with HgCl2. In contrast, LEW rats do not develop the characteristic glomerulonephritis and are very "low IgE responders". In this study, we examined the genetic control of total serum IgE increase after HgCl2 injection in F1 and F2 hybrids, in both backcrosses between LEW and BN rats, and in LEW.1N congenic rats. Genetic analysis was performed using peak IgE concentrations expressed as log microgram/ml. A high IgE phenotype was found to be dominant. Eighty-five percent of F2 variance was due to genetic factors (VG) while only 15% of this variance was caused by environmental factors (VE). From observations in F2 hybrids and backcrosses, estimations of additive variance (VA) and dominance variance (VD) were made following three different methods. Genetic control by about four loci is demonstrated. One of these genes is RT1-linked. This gene contributes to 25% of the phenotypic difference observed between BN and LEW rats. No correlation was found between the peak total IgE level and autoimmune disease based on IgG deposition in spleen and/or kidney.

Animals↗
PubMed1986

[Genetic analysis of mitochondrial rho-mutability in Saccharomyces. I. Polygenic determination of spontaneous rho-mutability: gene-modifiers and srm mutation].

The phenotypic trait "starry colony" in Saccharomyces is associated with a high spontaneous rho- petite mutability. Genetic analysis of this trait has shown the high rho- mutability to be caused by several modifying genes present together in the cell genome. Every single modifying gene only produces a relatively small enhancement in the rho- mutability. Mutations in four nuclear srm (spontaneous rho- mutability) loci were isolated after mutagenic treatment of highly rho- mutable haploid cells. In contrast to the modifying genes, each of these mutations has a pronounced effect on the spontaneous rho- mutability, causing significant decrease in it.

DNA, Fungal↗
PubMed1992

Selective breeding for increased cholinergic function: biometrical genetic analysis of muscarinic responses.

Biometric genetic analyses of behavioral and physiologic responses known to be related to muscarinic cholinergic receptors (hypothermia, hypoactivity, inhibited avoidance, and reduced responding for water) were studied in genetic crosses and backcrosses of the Flinders sensitive line (FSL) and Flinders resistant line (FRL) of rats. The FSL rats were more sensitive to the direct muscarinic agonists, arecoline and oxotremorine, and to the indirect agonist, physostigmine, than any other group. The next most sensitive group was the F1 x FSL backcross, followed by the F2, F1, F1 x FRL backcross, and the FRL, in that order. These differences between the genetic groups could be accounted for completely by either solely additive or additive plus dominance genetic factors. When dominance genetic factors contributed to the differences among groups (6 out of 15), the F1 responded like the FRL rats. The variance of the responses measured made it impossible to obtain reliable estimates of the number of genes involved in many instances; when such estimates were possible, several genes (greater than or equal to 3) appeared to be involved. We conclude that muscarinic sensitivity in rats is under genetic control, with the greatest contribution coming from additive genetic factors. Because the FSL rat appears to be a genetic animal model of depression, the finding of several genes influencing muscarinic responses may help account for the difficulties investigators have had in locating a single major gene or biological marker for human depressive disorders.

Analysis of Variance↗
PubMed1985

A genetic analysis of stereotypy in the mouse: dopaminergic plasticity following chronic stress.

After repeated stressful experiences, DBA/2 (DBA) mice showed an increase in apomorphine-induced climbing while C57BL/6 (C57) mice showed a clear-cut decrease of this behavior. Genetic analysis involving F1 and F2 hybrids and the backcross populations (F1 X C57; F1 X DBA) indicated complete dominance of the C57 genotype and a significant genotype X environment interaction. These findings are discussed in terms of dopaminergic plasticity and of the heuristic value of this animal model in relation to disturbed behaviors triggered by stressful experiences.

Animals↗
PubMed2004

Genetic analysis of TTF-2 gene in children with congenital hypothyroidism and cleft palate, congenital hypothyroidism, or isolated cleft palate.

Homozygous null mice for thyroid transcription factor (TTF)-2 gene exhibit cleft palate and thyroid malformation. We performed a genetic analysis of the TTF-2 gene in 2 children with congenital hypothyroidism (CH) and cleft palate, 45 children with thyroid dysgenesis, 19 children with isolated cleft palate or cleft lip, 4 patients with thyroid hemiagenesis. The entire coding-region of the TTF-2 gene was analyzed by direct sequencing. Direct sequencing of the TTF-2 gene revealed polymorphisms in the length of the polyalanine tract. The most frequent stretch length was 14 residues and it was found in 50 of 70 (71%) and in 45 of 53 (85%) normal healthy controls. A polyalanine tract of 16 residues in the heterozygous state was seen in 18 of 70 (26%) cases and in 4 of 53 (7%) normal subjects. In 1 of 4 (25%) case of hemiagenesis a polyalanine tract of 16 residues in the homozygous state was observed. In 1 of 26 agenesis the polyalanine tract consisted of 12 residues in the heterozygous state. Direct sequencing also revealed the presence of two silent polymorphisms. No mutations were identified in the TTF-2 gene. In conclusion, our results show that no genetic alteration was present in the TTF-2 gene of these patients, suggesting that defects in the TTF-2 gene are a rare event.

Adolescent↗
PubMed1990

[Genetic analysis of spontaneous and 6-N-hydroxylaminopurine and propiolactone induced Adp+ mutants in Saccharomyces yeasts].

652 spontaneous and 6-N-hydroxylaminopurine and propiolactone-induced mutants were obtained in yeast. 598 of them were LYS2 mutants. Detailed genetic analysis of the mutants was performed, including analysis of growth pattern on lysineless medium, suppressibility by nonsense suppressors of three types and localization on the recombination map of the LYS2 gene. Mutants induced by different agents were different for all these criteria, except for distribution among the map regions.

2-Aminoadipic Acid↗
PubMed2005

[Genetic analysis and molecular markers of a novel stripe rust resistance gene YrHua in wheat originated from Psathyrostachys huashanica Keng].

The H9020-17-5,a common wheat-Psathyrostachys huashanica Keng translocation line, possesses excellent resistance to wheat stripe rust. Genetic analysis of F2 and BC1 populations derived from H9020-17-5 x Mingxian169 indicated that resistance to stripe rust in H9020-17-5 was a dominant character controlling by single gene originated from Ps. huashanica. This resistance gene originated from Ps. huashanica was first reported in the present study and named as YrHua. In order to map the resistance gene YrHua, AFLP approach was employed to analyze the 119 individuals of H9020-17-5 x Mingxian169 F2 population which were inoculated by stripe rust isolate CY30. As a result,two markers, PM14(301) and PM42(249) were found to be linked to the resistance gene YrHua,and the genetic distances between the markers and target gene were 5.4 cM and 2.7 cM, respectively. For the convenience of marker-assisted selection in wheat breeding, one of the two AFLP markers was converted to PCR marker using a pair of special primers based on the DNA sequence of PM14 (301) and the polymorphism of restriction site. Our research results provided a useful tool for marker-assisted selection and laid a foundation of fine mapping and map based cloning of YrHua gene.

Base Sequence↗
PubMed2005

Genetic analysis of variation in gene expression in Arabidopsis thaliana.

In Arabidopsis thaliana, significant efforts to determine the extent of genomic variation between phenotypically divergent accessions are under way, but virtually nothing is known about variation at the transcription level. We used microarrays to examine variation in transcript abundance among three inbred lines and two pairs of reciprocal F1 hybrids of the highly self-fertilizing species Arabidopsis. Composite additive genetic effects for gene expression were estimated from pairwise comparisons of the three accessions Columbia (Col), Landsberg erecta (Ler), and Cape Verde Islands (Cvi). For the pair Col and Ler, 27.0% of the 4876 genes exhibited additive genetic effects in their expression (alpha = 0.001) vs. 32.2 and 37.5% for Cvi with Ler and Col, respectively. Significant differential expression ranged from 32.45 down to 1.10 in fold change and typically differed by a factor of 1.56. Maternal or paternal transmission affected only a few genes, suggesting that the reciprocal effects observed in the two crosses analyzed were minimal. Dominance effects were estimated from the comparisons of hybrids with the corresponding midparent value. The percentage of genes showing dominance at the expression level in the F1 hybrids ranged from 6.4 to 21.1% (alpha = 0.001). Breakdown of these numbers of genes according to the magnitude of the dominance ratio revealed heterosis for expression for on average 9% of the genes. Further advances in the genetic analysis of gene expression variation may contribute to a better understanding of its role in affecting quantitative trait variation at the phenotypic level.

Arabidopsis↗
PubMed2005

Aceruloplasminemia in an asymptomatic patient with a new mutation. Diagnosis and family genetic analysis.

A 39-year-old asymptomatic man showed elevated serum ferritin levels, mild hypertransaminasemia and serum ceruloplasmin almost undetectable. There was histological iron accumulation within the hepatocytes and also in the central nervous system (MRI). A genetic analysis revealed a new missense mutation in the ceruloplasmin gene. Two of the other four siblings were also affected by this mutation.

Adult↗
PubMed2003

Molecular genetic analysis for the Ae1 and A3 alleles.

BACKGROUND: In addition to the common ABO phenotypes, numerous phenotypes with a weak expression of the A or B antigens on RBCs have been found. This study describes the molecular genetic analysis of the Ael and the A3 phenotypes. STUDY DESIGN AND METHODS: The seven-exon regions of the ABO genes of Ael and A3B individuals were amplified by PCR and cloned, and the sequences of the exons and their adjacent splice sites were analyzed. Samples from 30 randomly selected A1 individuals were also assessed. RESULTS: The A gene with wild-type coding sequence was demonstrated in the Ael propositus, but all the six unrelated Taiwanese people with the Ael or AelB phenotype were shown to possess an A allele with the G-->A mutation at the +5 position of intron 6 (IVS6+5G-->A). RT-PCR analysis showed that the complete A transcript structure was absent in the Ael RNA samples. The A3B individual possessed an A gene with an 838C-->T missense mutation. CONCLUSION: The results suggest an association of the Ael*IVS6+5G-->A allele with the Ael phenotype in Taiwanese people. The mechanism defining how the Ael*IVS6+5G-->A allele leads to the Ael phenotype awaits elucidation.

ABO Blood-Group System↗
PubMed1991

A case of gastric plasmacytoma: genetic analysis and immunofixation electrophoresis.

A case of early gastric plasmacytoma in a 66-yr-old woman is reported. The demonstration of monotypic IgM lambda immunoglobulin in plasma cells infiltrating the gastric antrum contributed the histological diagnosis. Genetic analysis of the tumor cells confirmed the presence of a monoclonal neoplastic population of plasma cells in the tumor. Monoclonal immunoglobulin (IgM lambda) was demonstrated in serum, not by conventional immunoelectrophoresis, but by a highly sensitive immunofixation electrophoresis technique. Serum monoclonal immunoglobulin disappeared after subtotal gastrectomy. The value of immunofixation electrophoresis of serum protein and DNA analysis of tumor cells was emphasized for the diagnosis of gastric plasmacytoma.

Aged↗
PubMed1995

A genetic analysis of the Drosophila closely linked interacting genes bulge, argos and soba.

The Drosophila gene argos encodes a diffusible protein that acts as a negative regulator of cell fate decisions. To define interacting gene products, we performed a genetic analysis of argos, which suggests the presence of several partially redundant gene functions in its immediate vicinity at the chromosomal position 73A. Dose titration experiments have identified two of these loci. One of them corresponds to the gene bulge. Loss of function bulge alleles suppress the rough eye phenotype associated with overexpression of argos; conversely, amorphic argos mutations suppress the eye phenotype seen in flies bearing a single dominant bulge allele. Recombination mapping localized bulge 0.15 cM distal to argos. A second gene, suppressor of bulge and argos (soba), corresponds to the recently described lethal complementation group 73Aj. soba alleles suppress the eye phenotypes seen in flies expressing either the dominant bulge allele or the hs-argos construct. soba resides 120 kb proximal to argos. In addition, we have identified one allele of a new gene, clown, which like soba suppresses the eye phenotypes associated with hs-argos and bulgeDominant. clown maps on chromosome 3 at the cytological position 68CD.

Alleles↗
PubMed1976

Isolation and genetic analysis of mutant strains of Chlamydomonas reinhardi defective in gametic differentiation.

Impotent mutant strains of Chlamydomonas reinhardi, mating-type (mt) plus, are described that have normal growth and motility but fail to differentiate into normal gametes. Procedures for their isolation and their genetic analysis are described. Five of the imp strains (imp-2, imp-5, imp-l, imp-7, and imp-8) exhibit no flagellar agglutination when mixed with mt- or mt+ gametes and the mutations are shown to be unlinked to the mt locus (with the possible exception of imp-7). Two of the strains (imp-3 and imp-4) carry leaky mutations that affect cell fusion; neither mutation is found by tetrad analysis to be linked to mt or to the other. Cells of the imp-1 strain agglutinate well with mt- gametes and active agglutination continues for up to 48 hours, but cell fusion occurs only very rarely. Analysis of these rare zygotes indicates that imp-1 is closely linked to the mt+ locus, and fine-structural studies reveal that imp-1 gametes produce a mutant mating structure involved in zygotic cell fusion. The development of sexuality in C. reinhardi therefore appears amenable to genetic dissection.

Acetates↗