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A system for genetic analysis in gene lamB: first results with lambda-resistant tight mutants.

We describe a system for genetic analysis in gene lamb. It consists of a phage which allows mapping, complementation and sequencing studies of lamB mutations and of the sequence of gene lamB. We present results obtained with this system for a set of mutations conferring tight resistant to phage lambda. This leads to a first identification of three residues in the LamB protein which are important for adsorption of phage lambda h+. Residues 151 and 382 are important for reversible adsorption while residues 401 is important for irreversible adsorption. We briefly review other tight mutations affecting gene lamB and discuss some implications of the results on phage receptor interactions, LamB-protein structure and membrane insertion.

Adsorption↗

[Genetic analysis of differences in alkaline phosphatase activity in two Drosophila virilis strains differing in heat stress response].

Genetic control of changes in alkaline phosphatase activity was studied in adult individuals from two strains of Drosophila virilis under normal conditions and at a high temperature (38 degrees C). Flies from strain 101 responded to the heat shock with a reduction in enzyme activity, whereas flies from strain 147 lacked this response. Strains 101 and 147 were shown to differ in alkaline phosphatase activity at a normal temperature. Genetic analysis of these differences was performed. They were shown to be controlled monogenically (or by a battery of tightly linked genes). The gene determining alkaline phosphatase activity was localized on an autosome.

Alkaline Phosphatase↗

[Molecular genetic analysis of DNA structure of pFra plasmids in plague pathogen of varying biovar].

Data on comparative molecular genetic analysis of pFra plasmids from plague bacillus belonging to either two biovars (antiqua and orientalis) are presented. It was established that during evolution these replicons were rearranged, which resulted in the differences between pFra plasmids of plague bacillus of antiqua biovar (Yersinia pestis 231 and Y. pestis 358/12) and that of orientalis biovar (Y. pestis A1122 and Y. pestis EV). These included inversions of two plasmid DNA regions and size differences of 3 kb.

Evolution, Molecular↗

Genetic analysis of the T/t complex.

The T/t-complex has held considerable interest for immunologists, primarily because of its close genetic linkage to the major histocompatibility complex (MHC) on mouse chromosome 17. This interest has been heightened recently with the discovery that the MHC is fully contained within the t-complex and that two regions of the MHC, Qa and K, contain t-lethal genes. For a long time, T/t has been an enigmatic system, mainly because classical genetic analysis was not possible. Here the system is defined, recent information is presented, and our understanding of the mouse data to available information about the human MHC is correlated.

Animals↗

Genetic analysis of hedgehog signalling in the Drosophila embryo.

The segment polarity genes play a fundamental role in the patterning of cells within individual body segments of the Drosophila embryo. Two of these genes wingless (wg) and hedgehog (hh) encode proteins that enter the secretory pathway and both are thought to act by instructing the fates of cells neighbouring those in which they are expressed. Genetic analysis has identified the transcriptional activation of wg as one of the targets of hh activity: here we present evidence that transduction of the hh-encoded signal is mediated by the activity of four other segment polarity genes, patched, fused, costal-2 and cubitus interruptus. The results of our genetic epistatsis analysis together with the molecular structures of the products of these genes where known, suggest a pathway of interactions leading from reception of the hh-encoded signal at the cell membrane to transcriptional activation in the cell nucleus. We have also found that transcription of patched is regulated by the same pathway and describe the identification of cis-acting upstream elements of the ptc transcription unit that mediate this regulation.

Animals↗

Genetic analysis of sorted Hodgkin and Reed-Sternberg cells using comparative genomic hybridization.

Hodgkin and Reed-Sternberg (H and RS) cells are generally considered to be the neoplastic cells of Hodgkin's disease (HD); however, such cells are found only in a minority of HD lesions. Very few data have so far been published on the cytogenetic abnormalities in HD. An analysis of unknown genetic aberrations has only recently become possible through the use of comparative genomic hybridization (CGH), which is based on the competitive binding of tumor and control DNA to metaphase chromosomes. In order to exclude the reaction of non-tumor cells, we used 100 sorted H-RS cells as the tumor DNA, then 100 sorted reactive T cells or B cells as the control DNA. We obtained the amplified DNA, using degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). In addition, to confirm whether or not the lymphocytes in the background were reactive, we performed CGH with 100 sorted B cells and 100 sorted T cells. CGH was thus performed on 9 HDs, including 6 cases of mixed-cellularity (MC) sub-type and 3 cases of nodular-sclerosis (NS) sub-type. CGH of the B and T cells showed no genetic changes in any cases. In contrast, CGH of H-RS cells revealed both gains and losses of DNA in all 9 cases, and multiple changes were also observed. In situ hybridization showed an Epstein-Barr-virus infection in 5 cases of MC; however, no definite relationship was observed between the EBV infection and genetic changes. The most commonly observed genetic aberrations were a loss on 16q11/21 in 6 cases, a gain on 1p13 in 5 cases, and a gain on 7q35/36 in 5 cases. The large number of chromosomal alterations in HD suggests, therefore, that an increased degree of genetic instability play a role in the formation of H-RS cells.

Adult↗

Genetic analysis of HAV strains recovered from patients with acute hepatitis from Southern Italy.

Southern Italy is an endemic area for HAV infection contributing to the majority of Italian hepatitis A cases. Using molecular analysis, HAV strains have been classified in distinct genotypes and subgenotypes. To characterize HAV wild-type strains circulating in Southern Italy, sequence analysis of VP3-VP1 and VP1/2A junction regions of HAV isolates recovered from 25 patients with acute hepatitis during 2000 and 2001 was carried out. HAV isolates showed a degree of identity, after pairwise comparison with one another, ranging from 91.9-100% in the VP3-VP1 junction region and 89.9-100% in the VP1/2A junction region. All strains belonged to genotype I, with 84% (21/25) of samples clustering in subgenotype IA and 16% (4/25) in subgenotype IB. Cocirculation of subgenotypes IA and IB was observed among isolates from 2000, whereas all strains from 2001 were subgenotype IA. In addition, the subgenotype IA strains formed different clusters, one of which was related closely to some Cuban strains, showing a percent similarity of 98.8% in the 168-base pair segment encompassing the VP1/2A junction and the same amino acid substitution. The latter finding suggests that this subgenotype variant circulates also in the Mediterranean area. The results of the phylogenetic analysis confirm the genetic heterogeneity among HAV strains in Western Europe.

Acute Disease↗

Propylnitrosourea-induced T-lymphomas in LEXF RI strains of rats: genetic analysis.

Oral administration of propylnitrosourea (PNU) in drinking water induces high incidence of lympho-haemopoietic malignancies in rats. Previously we reported that F344 strain rats were highly susceptible to T-lymphomas, and LE/Stm rats, to erythro- or myeloid leukaemias. For analysis of the genetic factors determining types of diseases, we have established LEXF recombinant inbred strains of rats comprising 23 substrains, each derived from intercross between F344 and LE/Stm rats. Rats of 23 LEXF substrains were given PNU, and the development of tumours was observed. The overall incidence of haemopoietic tumours ranged from 100% to 66.7%, and the fractions of T-lymphomas, from 100% to 4%, showing a continuous spectrum. Based on the genetic profile published as a strain distribution pattern table for the LEXF, we screened the potential quantitative trait loci involved in determination of the types of disease and length of the latency period. Statistical calculation was performed using the Map Manager QT software developed by Manly. Four loci, on chromosome 4, 7, 10 and 18, were suggested to associate with the T-lymphoma susceptibility and three loci, on chromosome 1, 5 and 16, with the length of the latency period. These putative loci were further examined in backcross (F344 x LE)F1 x LE. Among seven loci suggested by the recombinant inbred study, three loci, on chromosome 5, 7 and 10, were significantly associated with T-lymphomas and another locus on chromosome 1, just weakly. These observations indicate that PNU-induced lymphomagenesis is a multifactorial genetic process involving a number of loci linked with susceptibility and resistance.

Animals↗

Genetic analysis of the 15;17 chromosome translocation associated with acute promyelocytic leukemia.

Somatic cell hybrids have been constructed between a thymidine kinase-deficient mouse cell line and blood leukocytes from a patient with acute promyelocytic leukemia showing the 15q+;17q- chromosome translocation frequently associated with this disease. One hybrid contains the 15q+ translocation chromosome and very little other human material. We have shown that the c-fes oncogene, which has been mapped to chromosome 15, is not present in this hybrid and, therefore, probably is translocated to the 17q- chromosome. Analysis of the genetic markers present in this hybrid has enabled a more precise localization of the translocation breakpoints on chromosomes 15 and 17. Our experiments also have enabled an ordering and more precise mapping of several genetic markers on chromosomes 15 and 17.

Adult↗

Genetic analysis using genomic representations.

Analysis of the genetic changes in human tumors is often problematical because of the presence of normal stroma and the limited availability of pure tumor DNA. However, large amounts of highly reproducible "representations" of tumor and normal genomes can be made by PCR from nanogram amounts of restriction endonuclease cleaved DNA that has been ligated to oligonucleotide adaptors. We show here that representations are useful for many types of genetic analyses, including measuring relative gene copy number, loss of heterozygosity, and comparative genomic hybridization. Representations may be prepared even from sorted nuclei from fixed and archived tumor biopsies.

Blotting, Southern↗

Genetic analysis of innate resistance to mouse cytomegalovirus (MCMV).

Innate immunity is inherited and is, therefore, particularly susceptible to analysis by classical genetic methods. The 'phenotype first' approach has already revealed the principal receptors of the innate immune system as well as several essential signalling intermediates. It has recently emerged that innate resistance to mouse cytomegalovirus (MCMV) infection depends upon a large number of host genes with non-redundant functions; hence, random germline mutagenesis frequently causes susceptibility to this pathogen. Approximately one in 30 pedigrees derived from N-ethyl-N-nitrosourea-mutagenised progenitors bears a recessive mutation that disrupts resistance to MCMV. Moreover, many of the genes required for resistance to MCMV will undoubtedly prove to have broad roles in immunity, creating resistance to many other microbes. The forward genetics approach offers an excellent opportunity to identify many of the key components of the innate immune system.

Animals↗

Genetic analysis of dermatoglyphic patterns in twins.

Analysis of variance was performed on 71 dermatoglyphic variables in 424 twin sets. Using a method of twin analysis estimates of genetic variance were obtained. 54 of the variables were quantitated using a scoring system with modifications of arch or no pattern = 0, loops = 1, whorl = 2. The results indicated a significant genetic influence in most pattern areas. Patterning was more genetically controlled in the hand than in the foot. The hallucal area had the most significant genetic component of the foot while the patterns in the thumb had nonsignificant components of genetic variance. The thumb deviated from patterning in the rest of the fingers and may be more closely related to big-toe patterning.

Dermatoglyphics↗

Genetic analysis of human obesity in an Italian sample.

An analysis of the genetic factors in obesity has been carried out on a sample of nuclear families from Aosta (N. Italy). The families consisted of the parents and sibs of all elementary school children considered to be obese during a preliminary screening and a similar sample of non-obese children and their nuclear families. The numbers of such families were 67 and 112, respectively. Several tests were applied in order to examine the genetic contribution to obesity, and in particular to investigate the presence of a dominant major gene. Our conclusions are that genetic factors are certainly present. Several analyses suggest the presence of a dominant major gene with weak effect.

Adipose Tissue↗

[Developmental genetic analysis of brown rice thickness of indica rice (Oryza sativa L.)].

Analysis of developmental genetic effects for brown rice thickness (BRT) trait in indica rice (Oryza sativa L.) at four different filling stages was conducted and a developmental genetic model and corresponding statistical approaches for quantitative traits of triploid endosperm in cereal crops was used. The results indicated that the diploid maternal plant, triploid endosperm and cytoplasmic genetic effects were important for BRT trait at all filling stages of rice and those effects were the major effect at initial medium, filling period and mature period respectively. The additive and dominance effects were the major effect alternatively at four filling stages of rice. Significant endosperm and maternal dominance effects for BRT suggest that the utilization of heterosis for BRT is viable. The results of conditional genetic variance components shown that the expression of new quantitative genes in endosperm, cytoplasm and maternal plant for BRT was found at most filling stages of rice. The gene expression was most active at the early filling stages, especially at the second stage (8-14 days after flowering). Near to mature period (22-28 days after flowering), however, the expression of genes decreased sharply and even closed. The phenomena that the genes expressed spasmodically, i.e. the net genetic effects equaled to zero in some filling stages were detected for some genetic effects. Dominance and cytoplasmic correlation coefficients were significant at 0.05 or 0.01 probability level in some filling stages meanwhile there were the most strong relationship between mature period and other periods for BRT.

Genetic Variation↗

Spontaneous colon cancer and its spontaneous regression in highly inbred Wistar Furth rats: genetic analysis.

The incidence of spontaneously occurring colon cancer and its spontaneous regression in the highly inbred Wistar Furth (WF) rat was studied using 1346 rats from the 19th to the 21st inbreeding generation. A statistical analysis revealed a positive phenotypical correlation between parents and offspring concerning the incidence of colon cancer and its spontaneous regression. The incidences of cancer-bearing offspring born from the crosses of cancer-free dams and cancer-bearing, spontaneous regression and cancer-free sires were 21%, 14.1% and 22.7%, respectively, and these results manifested a statistically significant difference. The incidences of spontaneous regression in the male offspring born from the same crosses mentioned above were 35%, 46.8% and 23.5%, respectively; they also represented a significant difference. Based on the analysis, two independent genetic factors, one carcinogenic and the another regressive, were suggested to determine the phenotypes of offspring. The cancer-bearing offspring have the carcinogenic factor but not the regressive factor, while the spontaneous regression ones have both factors. The frequencies of the carcinogenic and the regressive factors in male rats were estimated to be 54.1% and 59.8%, respectively, on average from the 19th to the 21st generation. A genetic pool of the carcinogenic and the regressive factors was established in the WF rat.

Animals↗

The acute phase response of mouse liver. Genetic analysis of the major acute phase reactants.

We have examined changes in translatable liver mRNAs during the acute phase response in several inbred mouse strains. Induction of mRNAs for the known acute phase reactants serum amyloid A, hemopexin, haptoglobin, and alpha 1-acid glycoprotein was observed. Two alpha 1-acid glycoproteins, termed AGP-1 and AGP-2, differing in size and charge, were found in all mice and appear to derive from distinct yet closely related mRNAs. Polymorphism in the structure of AGP-1 among strains was used to map the structural gene, Agp-1, to chromosome 4 near the b locus. Structural variation for serum amyloid A enabled mapping its structural gene, S alpha alpha, to chromosome 7, near Gpi-1. A wild-derived population of mice, Mus spretus, contains several variations of interest, including structural variations in many acute phase proteins and a putative regulatory variation specific to AGP-1. Further analysis of these genetic variants should provide novel insights into the acute phase response and the factors that mediate it.

Animals↗

[A genetic analysis of the structure of hybrid populations of the green frog Rana esculenta L. complex (Amphibia, Ranidae) in Volhynia].

Analysis of the genetic structure of two green frog Rana esculenta complex populations from Volyn' was performed for 7 diagnostical loci. Populations of R- and REL-type were detected in which the introgression of Ldh-B allelic gene locus from R. lessonae into genome of R. ridibunda, characteristic for hybrid populations of Dnieper basin, was absent. This may be associated with alterations in gene pools of parental species.

Alleles↗