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PubMedDate not supplied

Dynamics of correlated genetic systems. VI. Variation in recombination rates in experimental populations of Drosophila melanogaster.

Recombination fractions among four chromosome 3 enzyme loci were measured over a 20 generation period in experimental populations of Drosophila melanogaster. The experimental populations were initiated with complete pairwise linkage disequilibria among the marker loci, thereby providing an initial structure favorable to selection for recombination modification. The recombination data show no evidence of directional changes in recombination rates among the marker loci, although variation in estimates, both between families within generations and between generations was large. These materials also yielded much lower estimates for recombination fractions for the centromeric region of the third chromosome than previously reported. Taken in total, the experimental results show no evidence for recombination modification, although the results do indicate ample genetic variance for recombination rates.

Animals↗
PubMed2005

Murine cytomegalovirus resistant to antivirals has genetic correlates with human cytomegalovirus.

Human cytomegalovirus (HCMV) resistance to antivirals is a significant clinical problem. Murine cytomegalovirus (MCMV) infection of mice is a well-described animal model for in vivo studies of CMV pathogenesis, although the mechanisms of MCMV antiviral susceptibility need elucidation. Mutants resistant to nucleoside analogues aciclovir, adefovir, cidofovir, ganciclovir, penciclovir and valaciclovir, and the pyrophosphate analogue foscarnet were generated by in vitro passage of MCMV (Smith) in increasing concentrations of antiviral. All MCMV antiviral resistant mutants contained DNA polymerase mutations identical or similar to HCMV DNA polymerase mutations known to confer antiviral resistance. Mapping of the mutations onto an MCMV DNA polymerase three-dimensional model generated using the Thermococcus gorgonarius Tgo polymerase crystal structure showed that the DNA polymerase mutations potentially confer resistance through changes in regions surrounding a catalytic aspartate triad. The ganciclovir-, penciclovir- and valaciclovir-resistant isolates also contained mutations within MCMV M97 identical or similar to recognized GCV-resistant mutations of HCMV UL97 protein kinase, and demonstrated cross-resistance to antivirals of the same class. This strongly suggests that MCMV M97 has a similar role to HCMV UL97 in the phosphorylation of nucleoside analogue antivirals. All MCMV mutants demonstrated replication-impaired phenotypes, with the lowest titre and plaque size observed for isolates containing mutations in both DNA polymerase and M97. These findings indicate DNA polymerase and protein kinase regions of potential importance for antiviral susceptibility and replication. The similarities between MCMV and HCMV mutations that arise under antiviral selective pressure increase the utility of MCMV as a model for in vivo studies of CMV antiviral resistance.

Acyclovir↗
PubMed1993

Isolation of cDNAs encoding 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase from the mediterranean fruit fly Ceratitis capitata: correlating genetic and physical maps of chromosome 5.

We have isolated and determined the nucleotide sequences for cDNA clones encoding glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) from the medfly Ceratitis capitata. The derived amino acid sequences for G6PD and 6PGD are presented and compared with G6PDs and 6PGDs from other species. The codon usage of the cDNA clones has little bias with the notable exceptions of arginine, glycine and leucine. The chromosomal location of the genes for 6PGD and G6PD were determined by in situ hybridization to salivary gland polytene chromosomes. This localization orients a genetic map of enzymatic loci and illustrates a remarkable similarity in the intra chromosomal order of homologous genes between Drosophila melanogaster and medfly.

Amino Acid Sequence↗
PubMed1978

Correlated genetic and EcoRI cleavage map of Bacillus subtilis bacteriophage phi105 DNA.

The seven previously identified EcoRI cleavage fragments of phi 105 DNA were ordered with respect to their sites of origin on the phage genome by marker rescue. One fragment, H, did not carry any determinants essential for replication. This fragment was totally missing in a deletion mutant which exhibited a lysogenization-defective phenotype. There is a nonessential region on the phi 105 genome which begins in fragment B, spans fragment H, and ends in fragment F. The size of the nonessential region, as estimated by alterations observed in the fragmentation patterns of deletion mutant DNAs, is approximately 2.7 X 10(6) daltons. Two new EcoRI cleavage fragments with molecular weights of approximately 0.2 X 10(6) were detected by autoradiography of 32P-labeled DNA. These small fragments were not located on the cleavage map.

Bacillus subtilis↗
PubMed1975

Central core disease. A correlated genetic, histochemical, ultramicroscopic, and biochemical study.

Two patients suffering from central core disease are presented. The condition is associated with musculoskeletal abnormalities which have been traced back over five generations. In addition to the typical histochemical findings, electronmicroscopic study has revealed the presence of both structured and non-structured cores in adjacent areas. The calcium uptake by the sarcoplasmic reticulum was reduced to one-third of normal. Phosphorylase activity was normal in the one case and reduced to 63% in the other. Actomyosin Mg2+-activated ATPase activity was decreased, as was the Ca2+-dependent ATPase of the sarcoplasmic reticulum.

Adenosine Triphosphatases↗
PubMed1997

Primary adhalinopathy (alpha-sarcoglycanopathy): clinical, pathologic, and genetic correlation in 20 patients with autosomal recessive muscular dystrophy.

Primary adhalin (or alpha-sarcoglycan) deficiency due to a defect of the adhalin gene localized on chromosome 17q21 causes an autosomal recessive myopathy. We evaluated 20 patients from 15 families (12 from Europe and three from North Africa) with a primary adhalin deficiency with two objectives: characterization of the clinical phenotype and analysis of the correlation with the level of adhalin expression and the type of gene mutation. Age at onset and severity of the myopathy were heterogeneous: six patients were wheel-chair bound before 15 years of age, whereas five other patients had mild disease with preserved ambulation in adulthood. The clinical pattern was similar in all the patients with symmetric characteristic involvement of trunk and limb muscles, calf hypertrophy, and absence of cardiac dysfunction. Immunofluorescence and immunoblot studies of muscle biopsy specimens showed a large variation in the expression of adhalin. The degree of adhalin deficiency was fairly correlated with the clinical severity. There were 15 different mutations (10 missense, five null). Double null mutations (three patients) were associated with severe myopathy, but in the other cases (null/missense and double missense) there was a large variation in the severity of the disease.

Adolescent↗
PubMed2003

Correlating genetic aberrations with World Health Organization-defined histology and stage across the spectrum of thymomas.

Thymomas are thymic epithelial tumors. Because most of them are rich in nonneoplastic T-cells, recurrent genetic aberrations have been reported only in the rare, lymphocyte-poor WHO types A, B3, and C. We have now investigated virtually the whole spectrum of thymomas, including the commoner types AB and B2, microdissecting or culturing neoplastic cells from these lymphocyte-rich thymomas and applying 41 microsatellite markers covering 17 loci on 10 chromosomes. In 28 cases, comparative genomic hybridization data were available. Apart from type A, there was striking heterogeneity between thymomas. Allelic imbalances were seen in 87.3% of the 55 cases, and MSI in 9.9%. Losses of heterozygosity (LOHs) were much the commonest aberration. Overall, they were most prevalent at four regions on chromosome 6. Aberrations elsewhere, affecting mainly 8p11.21 and 7p15.3, suggested a cortical footprint because they recurred only in the thymopoietically active type AB and B thymomas. LOHs were also seen at the adenomatous polyposis coli (APC) locus (5q21-22) in subsets of these thymomas, whereas combined LOHs at the APC, retinoblastoma (13q14.3), and p53 (17p13.1) loci were confined to a subset of B3 thymomas that had possibly evolved from APC-hemizygous B2 thymomas by tumor progression; indeed, thymomas combing B2 plus B3 features are common. Notably, some AB and B thymomas shared LOHs despite their nonoverlapping morphology and different clinical behavior. Finally, allelic imbalances at 8p11.21 and 16q22.1 (CDH1) were significantly more frequent in stage IV metastatic thymomas. We conclude that the WHO-defined histological thymoma types generally segregate with characteristic genetic features, type A thymomas being the most homogeneous. Many findings support the view that B2 and B3 thymomas form a continuum, with evidence of tumor progression. However, other findings imply that types A and AB are biologically distinct from the others, any potential invasiveness being severely restricted by a medullary commitment in the precursor cell undergoing neoplastic transformation.

Cells, Cultured↗
PubMed2003

Pharmacological action and therapeutic effects of glutathione on hypokinetic spermatozoa for enzymatic-dependent pathologies and correlated genetic aspects.

In this study, the pharmacologic substance reduced glutathione (GSH) was used in men with hypofertility problems linked to varicocele, in bulls with spermatozoa hypomobility due to varicocele, and in rabbits with dispermy caused by cryptorchidism. An efficacious therapeutic effect of increased motility of the spermatozoa was seen in subjects who were submitted to appropriate doses of glutathione I.M. GSH also showed some neutralizing effect on the catabolytes produced during spontaneous or induced peroxidation processes of the unsaturated lipids contained in the membranes of male germinal cells. The genetic aspects of the involved enzymes were also evaluated and the research was extended in vitro by incubating samples of spermatozoa with arachidonic acid homogenates, L-tryptophan, hematein, and with an addition of glutathione. The results showed that polynsaturated fatty acid metabolic substances (PUFA) play an important role in the acrosomal reaction of spermatozoa and that GSH has a determining role in increasing the motility of spermatozoa with consequent improved fertilization. The spermatozoa of bulls provided us with a valid model to study for the morphostructural, biochemical and pharmacological analyses of human spermatozoa.

Animals↗
PubMed2006

Serrated pathway and APC (conventional)-type colorectal polyps: molecular-morphologic correlations, genetic pathways, and implications for classification.

This review addresses the genetic mutations and cell signaling pathway alterations in colorectal premalignant polyps, focusing on the link between molecular changes and morphologic features. Biallelic APC (adenomatous polyposis coli) mutations are directly responsible for the specific and characteristic cytologic features of dysplastic cells in conventional tubular adenomas. Sessile serrated adenomas (SSAs) are the precursor lesions of the serrated neoplasia pathway. The BRAF activating mutation and hypermethylation of SLC5A8, which mediates short chain fatty acid transport, may be the important events in the genesis of SSAs. Intracellular butyrate inhibits histone deacetylase, allowing histone hyperacetylation and, eventually, transcriptional activation of specific genes. Decreased p21(WAF1/CIP1) and activation of the mitogen-activated protein kinase pathway may be the key intermediary alterations. Progressive loss of cell cycle control and decreased and altered cytoplasmic differentiation produce the characteristic constellation of morphologic changes of SSAs and traditional serrated adenomas.

Adaptor Proteins, Signal Transducing↗
PubMed1985

[Anti-thymocyte antibodies in schizophrenia: clinico-immunologic and genetic correlations].

The blood levels of anti-thymocytic IgG, IgM and IgA were studied in schizophrenics, their relatives and normal donors. The schizophrenic patients and their relatives had significantly elevated levels of IgG and IgM. The increased level of IgG in schizophrenic patients may be considered as a reflection of the pathological process or, perhaps, as a response to disease exacerbation. A high concentration of IgM is implicated in hereditary liability to schizophrenia being a significant although insufficient component of the patient's ability to develop the disease.

Adult↗