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At least 703 records · Page 39Linked to original sources
PubMed2001

Genetic analysis of the Epstein-Barr virus-coded leader protein EBNA-LP as a co-activator of EBNA2 function.

Co-operation between the Epstein-Barr virus (EBV)-coded leader protein EBNA-LP and the nuclear antigen EBNA2 appears to be critical for efficient virus-induced B cell transformation. Here we report the genetic analysis of EBNA-LP function using two transient co-transfection assays of co-operativity, activation of latent membrane protein 1 (LMP1) expression from a resident EBV genome in Akata-BL cells and activation of an EBNA2-responsive reporter construct. Small deletions were introduced into each of five conserved regions (CRs) of EBNA-LP sequence present in type 1 and type 2 EBV strains and in several primate lymphocryptovirus EBNA-LP homologues. Deletions within all three CRs in the EBNA-LP W1W2 repeat domain completely abrogated function, through inhibition of nuclear localization in the cases of CR1 and CR2 but not of CR3; deletions within CR4 and CR5 in the Y1Y2 unique domain had relatively little effect, yet loss of the whole Y2 sequence blocked activity. Alanine substitution of serine residues within potential phosphorylation sites identified two mutants of particular interest. Substitution of three such residues (S34,36,63) within W1W2 not only abrogated EBNA-LP activity but was associated with a complete loss of EBNA2 detectability in co-transfected cells, implying possible destabilization of the co-expressed EBNA2 protein. More importantly the individual substitution of S36 completely blocked EBNA-LP/EBNA2 co-operativity while retaining EBNA2 expression. We infer critical roles for the CR3 domain and for the S36 residue in EBNA-LP's co-operative function.

Alanine↗
PubMed2003

Quantitative genetic analysis of among-population variation in sperm and female sperm-storage organ length in Drosophila mojavensis.

In Drosophila, sperm length and the length of the females' primary sperm-storage organ have rapidly coevolved through post-copulatory sexual selection. This pattern is evident even among geographic populations of Drosophila mojavensis. To understand better these traits of potential importance for speciation, we performed quantitative genetic analysis of both seminal receptacle length and sperm length in two divergent populations. Parental strains, F1, F1 reciprocal (F1r), F2, F2r, backcross and backcross reciprocal generations were used in a line-cross (generation means) analysis. Seminal receptacle length is largely an autosomal additive trait, whereas additivity, dominance and epistasis all contributed to the means of sperm length. Either an X-chromosome or a Y-chromosome effect was necessary for models of sperm length to be significant. However, the overall contributions from the X and Y chromosomes to sperm length was small.

Animals↗
PubMed2002

GENEHUNTER: your 'one-stop shop' for statistical genetic analysis?

The past decade has brought a proliferation of statistical genetic (linkage) analysis techniques, incorporating new methodology and/or improvement of existing methodology in gene mapping, specifically targeted towards the localization of genes underlying complex disorders. Most of these techniques have been implemented in user-friendly programs and made freely available to the genetics community. Although certain packages may be more 'popular' than others, a common question asked by genetic researchers is 'which program is best for me?'. To help researchers answer this question, the following software review aims to summarize the main advantages and disadvantages of the popular GENEHUNTER package.

Chromosome Mapping↗
PubMed1992

Molecular genetic analysis of HLA-DR and HLA-DQ genes among anti-U1-70-kd autoantibody positive connective tissue disease patients.

OBJECTIVE: We have recently found that the presence of autoantibodies against the 70-kd polypeptide of U1 RNP (U1-70-kd) is associated with HLA-DR4 and DR2. To further characterize this association, we performed a molecular genetic analysis of HLA-DR and DQ genes among patients with autoantibodies against U1-70-kd. METHODS: The polymerase chain reaction (PCR), sequence-specific oligonucleotide hybridization, and solid-phase direct DNA sequencing of PCR-amplified DNA were utilized to analyze HLA-DRB1, DRB5, DQA1, and DQB1 genes. RESULTS: A comprehensive analysis of HLA-DRB1, DRB5, DQA1, and DQB1 from 27 patients and controls identified shared amino acids FDYFYQA (Phe, Asp, Tyr, Phe, Tyr, Gln, Ala) at positions 26, 28, 30-32, 70, and 73 of HLA-DRB1 on disease-associated haplotypes. CONCLUSION: A common cluster of shared amino acids, or a shared epitope, identified within HLA-DRB1 among anti-U1-70-kd autoantibody positive connective tissue disease patients may be important in regulating an autoimmune response to the U1-70-kd antigen.

Amino Acid Sequence↗
PubMed1993

Molecular and genetic analysis of the SNF7 gene in Saccharomyces cerevisiae.

Mutations in the SNF7 gene of Saccharomyces cerevisiae prevent full derepression of the SUC2 (invertase) gene in response to glucose limitation. We report the molecular cloning of the SNF7 gene by complementation. Sequence analysis predicts that the gene product is a 27-kDa acidic protein. Disruption of the chromosomal locus causes a fewfold decrease in invertase derepression, a growth defect on raffinose, temperature-sensitive growth on glucose, and a sporulation defect in homozygous diploids. Genetic analysis of the interactions of the snf7 null mutation with ssn6 and spt6/ssn20 suppressor mutations distinguished SNF7 from the SNF2, SNF5 and SNF6 genes. The snf7 mutation also behaved differently from mutations in SNF1 and SNF4 in that snf7 ssn6 double mutants displayed a synthetic phenotype of severe temperature sensitivity for growth. We also mapped SNF7 to the right arm of chromosome XII near the centromere.

Amino Acid Sequence↗
PubMed1995

A genetic analysis of intersex, a gene regulating sexual differentiation in Drosophila melanogaster females.

Sex-type in Drosophila melanogaster is controlled by a hierarchically acting set of regulatory genes. At the terminus of this hierarchy lie those regulatory genes responsible for implementing sexual differentiation: genes that control the activity of target loci whose products give rise to sexually dimorphic phenotypes. The genetic analysis of the intersex (ix) gene presented here demonstrates that ix is such a terminally positioned regulatory locus. The ix locus has been localized to the cytogenetic interval between 47E3-6 and 47F11-18. A comparison of the morphological and behavioral phenotypes of homozygotes and hemizygotes for three point mutations at ix indicates that the null phenotype of ix is to transform diplo-X animals into intersexes while leaving haplo-X animals unaffected. Analysis of X-ray induced, mitotic recombination clones lacking ix+ function in the abdomen of diplo-X individuals indicates that the ix+ product functions in a cell-autonomous manner and that it is required at least until the termination of cell division in this tissue. Taken together with previous analyses, our results indicate that the ix+ product is required to function with the female-specific product of doublesex to implement appropriate female sexual differentiation in diplo-X animals.

Alleles↗
PubMed2006

Molecular genetic analysis of 1053 Danish individuals with clinical signs of familial hypercholesterolemia.

The lipid disorder familial hypercholesterolemia (FH) predisposes to cardiovascular disease. With a prevalence of approximately one in 500 in the general Caucasian population, FH is one of the most frequent single-gene disorders. As the mutational spectra vary between populations, it is crucial to identify the mutations in a given population in order to implement a molecular genetic screening strategy. A total of 1053 referred individuals with clinical signs of FH were investigated, and mutations were identified in 425 individuals. Fifty-four different mutations were identified, of which 13 are novel. The five most frequent mutations accounted for 56.3% of all disease-causing mutations. The majority of the remaining mutations were of a private nature only encountered in single families. In this study, a reliable molecular genetic screening protocol was established, and the relevance of performing presymptomatic genetic analysis as part of a preventive strategy was documented. We have acquired knowledge of the mutational spectra in the Danish population and thus will be able to trace mutations in their relatives through our index cases.

Apolipoprotein B-100↗
PubMed2001

Genetic analysis of the Sinorhizobium meliloti BacA protein: differential effects of mutations on phenotypes.

Sinorhizobium meliloti strains lacking BacA function are impaired in symbiosis with alfalfa host plants and display altered sensitivities to a number of compounds relative to wild-type strains. With the goal of finding clues to the currently unknown biological function(s) of BacA, we carried out a genetic analysis to determine which amino acids are critical for protein function and to attempt to ascertain whether the multiple phenotypes that result from a bacA-null allele were the result of a common cause or whether BacA has multiple functions. We have created a set of 20 site-directed mutants in which selected individual amino acids in bacA were replaced with glycine residues. The resulting mutants were characterized to determine how the various amino acid changes affected a number of phenotypes associated with loss of BacA function. Mutants H165G, W182G, D198G, and R284G had null phenotypes for all functions assayed, while mutants W57G, S83G, S231G, and K350G were indistinguishable from wild-type strains. The remaining 12 site-directed mutants demonstrate mixed phenotypic characteristics and fall into a number of distinctly different groups. These observations may be consistent with a role for BacA in multiple, nonoverlapping functions.

Amino Acid Sequence↗
PubMed2002

Molecular genetic analysis of the NF2 gene in young patients with unilateral vestibular schwannomas.

Neurofibromatosis type 2 (NF2) must be suspected in patients presenting with a unilateral vestibular schwannoma at a young age who are therefore at theoretical risk of developing bilateral disease. We identified 45 patients aged 30 years or less at the onset of symptoms of a unilateral vestibular schwannoma. Molecular genetic analysis of the NF2 gene was completed on peripheral blood samples in all 45 and on 28 tumour samples. No pathogenic NF2 mutations were identified in any of the blood samples. NF2 point mutations were identified in 21/28 (75%) tumour samples and loss of heterozygosity (LOH) in 21/28 (75%) tumour samples. Both mutational hits were identified in 18/28 (65%) tumour samples. In one multilobular tumour, one (presumably first hit) mutation was confirmed which was common to different foci of the tumour, while the second mutational event differed between foci. The molecular findings in this patient were consistent with somatic mosaicism for NF2 and the clinical diagnosis was confirmed with the presence of two meningiomas on a follow up MRI scan. A further patient developed a contralateral vestibular schwannoma on a follow up MRI scan in whom neither of the truncating mutations in the vestibular schwannoma were present in blood. It is important when counselling patients with unilateral vestibular schwannomas to identify (1) those at risk of bilateral disease, (2) those at risk of developing other tumours, and (3) other family members at risk of developing NF2. Comparing tumour and blood DNA cannot exclude mosaicism in the index case and cannot, therefore, be used to predict those at risk of developing further tumours. However, identification of both mutations or one mutation plus LOH in the tumour and exclusion of those mutations in the blood samples of the sibs or offspring of the affected case may be sufficient to render further screening unnecessary in these relatives.

Adolescent↗
PubMed1979

[Yeast resistance to polyene antibiotics. I. Production of Saccharomyces cerevisiae mutants resistant to nystatin and their genetic analysis].

239 nistatin-resistant mutants were selected after UV-irradiation of yeasts. Phenotypical analysis has revealed two main groups of the mutants: 1) resistant to nistatin and resistant or sensitive (in different combinations) to haptaens; 2) resistant to nistatin and having an increased resistance to haptens. It is found that the sensitivity dominates over the resistance and hyper-resistance. Genetic analysis of the mutant collection has shown that the resistance to nistatin is determined by 5 nuclear genes (hysr). Hyper-resistance is controlled by mutations in other genes, which are not connected with stable phenotype. Genes of hyper-resistance can be considered as minus-modificators of pleiothrophic cross-resistance, characteristic of hysr genes. Plus-modificator genes of polyenic resistance are described. The gene hysr1 is linked with its chromosome.

Crosses, Genetic↗
PubMed2005

Approach to genetic analysis in the diagnosis of hereditary autoinflammatory syndromes.

OBJECTIVE: Hereditary autoinflammatory syndromes are characterized by recurrent episodes of fever and inflammation. Seven subtypes have been described, caused by mutations in four different genes. Apart from a common phenotype of lifelong recurrent inflammatory attacks, all subtypes have distinct features and specific therapeutic options, which emphasizes the need for a specific diagnosis in each case. Our aim was to examine whether genetic screening would allow classification of previously unclassified patients, and whether individual patients suffering from an autoinflammatory syndrome carry additional mutations in one of the other autoinflammatory genes. METHODS: We included 60 patients with an unclassified autoinflammatory syndrome, 87 patients diagnosed with either hyper-IgD syndrome, familial Mediterranean fever (FMF) or tumour necrosis factor (TNF)-receptor-associated periodic syndrome and 50 healthy controls. Deoxyribonucleic acid samples were screened for the most prevalent mutations in the MEFV, TNFRSF1A, MVK and CIAS1 genes. RESULTS: We found only one possible diagnosis of FMF in the 60 previously unclassified patients. Two low-penetrance mutations were found in equal numbers in the groups of patients and controls. CONCLUSIONS: Screening of highly prevalent mutations in known genes involved in these disorders does not yield additional relevant information. Differential diagnosis of hereditary autoinflammatory syndromes can be made by thorough clinical examination followed by targeted genetic analysis of the one or two most likely syndromes. High-prevalence low-penetrant mutations from autoinflammatory genes do not occur more frequently in patients with hereditary autoinflammatory syndromes compared with the general population.

Adolescent↗
PubMed1987

A genetic analysis of glutamatergic function in Drosophila.

Neurotransmitters are essential for communication between neurons and hence are vital in the overall integrative functioning of the nervous system. Previous work on acetylcholine metabolism in the fruit fly, Drosophila melanogaster, has also raised the possibility that transmitter metabolism may play a prominent role in either the achievement or maintenance of the normal structure of the central nervous system in this species. Unfortunately, acetylcholine is rather poorly characterized as a neurotransmitter in Drosophila; consequently, we have begun an analysis of the role of glutamate (probably the best characterized transmitter in this organism) in the formation and/or maintenance of nervous system structure. We present here the results of a series of preliminary analyses. To suggest where glutamatergic function may be localized, an examination of the spatial distribution of high affinity [3H]-glutamate binding sites are presented. We present the results of an analysis of the spatial and temporal distribution of enzymatic activities thought to be important in the regulation of transmitter-glutamate pools (i.e., glutamate oxaloacetic transaminase, glutaminase, and glutamate dehydrogenase). To begin to examine whether mutations in any of these functions are capable of affecting glutamatergic activity, we present the results of an initial genetic analysis of one enzymatic function, glutamate oxaloacetic transaminase (GOT), chosen because of its differential distribution within the adult central nervous system and musculature.

Animals↗
PubMed1985

Automating data manipulation for genetic analysis using a data base management system.

Inefficient coding and manipulation of pedigree data have often hindered the progress of genetic studies. In this paper we present the methodology for interfacing a data base management system (DBMS) called MEGADATS with a linkage analysis program called LIPED. Two families that segregate a dominant trait and one test marker were used in a simulated exercise to demonstrate how a DBMS can be used to automate tedious clerical steps and improve the efficiency of a genetic analysis. The merits of this approach to data management are discussed. We conclude that a standardized format for genetic analysis programs would greatly facilitate data analysis.

Genetics, Medical↗
PubMed1992

Molecular genetic analysis of a class B periplasmic-flagellum gene of Treponema phagedenis.

Treponema phagedenis is a host-associated spirochete with multiple polypeptides making up its periplasmic flagella (PFs). Each PF has a 39-kDa polypeptide making up the sheath (class A PF polypeptide) and two to four antigenically similar 33- to 34-kDa polypeptide species making up the core (class B PF polypeptides). A genetic analysis of the PF-deficient mutants T-40 and T-55 has shown that the PFs are involved in motility. To better understand the synthesis and assembly of these complex organelles and to compare the PF genes with those of other spirochetes, we cloned and characterized the T. phagedenis flaB2 gene, which encodes one class B polypeptide. The flaB2 gene consists of an open reading frame of 858 nucleotides capable of encoding a protein of 31.5 kDa. The predicted amino acid sequence of the FlaB2 polypeptide was 92% identical to that of T. pallidum FlaB2, with a 76% identity at the nucleotide level. These results confirm previous immunological and N-terminal-sequence analyses which suggested that the PF genes are well conserved in the spirochetes. Primer extension analysis of T. phagedenis flaB2 indicated that the start site of transcription was 127 nucleotides upstream from the ATG initiation codon. Preceding the start site is a DNA sequence similar to the sigma 28 consensus promoter sequence commonly found associated with motility genes. Northern (RNA) blots probed with a segment of flaB2 DNA revealed a 1,000-nucleotide monocistronic transcript in the wild type and in PF-deficient mutants T-40 and T-55. DNA sequencing of most of the flaB2 gene of the mutants revealed no differences from the wild-type gene. Because the mutants fail to synthesize detectable class B PF polypeptides yet synthesize extensive amounts of flaB2 mRNA, PF synthesis in T. phagedenis is likely to involve regulation at the translational level.

Amino Acid Sequence↗
PubMed1982

Genetic analysis of life-span in Caenorhabditis elegans.

Crosses between Bristol and Bergerac strains of the self-fertilizing hermaphroditic nematode Caenorhabditis elegans do not show the heterosis effects for life-span that complicate analysis of interstrain crosses with Drosophila or mice. Instead they yield F1 progeny with life-spans similar to those of the parent strains. By analysis of life-span variation among progeny F2 populations from such crosses and by two independent analyses of life-spans among recombinant inbred lines derived from F2 individuals by 18 rounds of self-fertilization, we estimate that the heritability of life-span in C. elegans is between 20% and 50%. Recombinant inbred lines show a range in mean life-spans of 10 days to 31 days compared to life-spans of about 18 days for each of the two parental strains. We conclude that life-span variation in C. elegans has a substantial genetic component and that this organism offers promising opportunities for selective breeding of longer-lived strains and genetic analysis of senescence.

Aging↗
PubMed2002

Genetic analysis of nicotinic signaling in worms and flies.

The nicotinic acetylcholine receptor is among the most thoroughly characterized molecules in the nervous system, and its role in mediating fast cholinergic neurotransmission has been broadly conserved in both vertebrates and invertebrates. However, the accessory molecules that facilitate or regulate nicotinic signaling remain mostly unknown. One approach to identify such molecules is to use molecular genetics in a simple, experimentally accessible organism to identify genes required for nicotinic signaling and to determine the molecular identity of the mutant genes through molecular cloning. Because cellular signaling pathways are often highly conserved between different animal phyla, the information gained from studies of simple organisms has historically provided many critical insights into more complex organisms, including humans. Genetic screens essentially make no prior assumptions about the types of molecules involved in the process being studied; thus, they are well suited for identifying previously unknown components of cell signaling pathways. The sophisticated genetic tools available in organisms such as the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster have also proven extremely powerful in elucidating complex biologic pathways in the absence of prior biochemical information and for assessing a molecule's in vivo function of in the context of an intact nervous system. This review describes how genetic analysis has been used to investigate nicotinic signaling mechanisms in worms and flies, and the prospects for using these studies to gain insight into nicotinic receptor function and regulation in humans.

Animals↗
PubMed1999

Molecular and genetic analysis of the Tribolium Ultrabithorax ortholog, Ultrathorax.

Ultrabithorax (Ubx) is essential for the proper patterning of the posterior thorax and anterior abdomen in Drosophila. The Coleoptera and Diptera differ in the organization and structure of their thorax and anterior abdomen. Changes in the regulation of Ubx and/or its downstream target genes are predicted to underlie these altered morphologies. We exploited the feasibility of genetic analysis in the red flour beetle, Tribolium castaneum, to examine the role of its Ubx ortholog in development. We analyzed genomic and cDNA clones that predict a polypeptide with nearly 100% identity with the Drosophila Ubx gene in the homeodomain and flanking sequences. Southern blot analysis indicates that these clones represent DNA sequences within the Homeotic complex (HOM-C) of Tribolium. Phenotypic analysis of mutant variants of the Ultrathorax (Utx) gene, and its location within the beetle HOM-C, strongly supports Utx being the Tribolium ortholog of Ubx. The embryonic expression pattern of Ubx-homologous transcripts coincides with the phenotypes associated with Utx mutations, providing support that the Ubx-homologous cloned DNA represents the Utx locus. By mid-germband extension Utx transcripts are expressed in a pattern similar to Ubx in Drosophila. However, during early germband formation Utx transcripts differ in both spatial and temporal progression. Utx expression is initially detected in parasegments 4 and 5 (T1p-T3a) as they are established during early germband formation. This is the first report of the wild-type parasegmental expression of an insect Ubx ortholog extending through parasegment 4. The earlier and more anterior expression in the thorax may underlie the modification of the Coleopteran thorax.

Amino Acid Sequence↗
PubMed2000

Genetic analysis of fetal nucleated red blood cells from CVS washings.

Chorionic villus sampling (CVS) is an established invasive prenatal diagnostic method for the detection of fetal chromosome aberrations. In 1-2% the karyotype result of CVS is inconclusive and follow-up confirmation will be required. To avoid another invasive procedure we examined fetal nucleated red blood cells (NRBCs) from CVS washings for genetic analysis. We analysed the washings of 20 chorionic villi samples of male fetuses. Fetal NRBCs were immunostained by an antibody against embryonic haemoglobin (HbE). FISH was performed with probes specific for the X and Y chromosome and the nucleus was counterstained with DAPI. Cells positive for the antibody, as well as for DAPI, were collected and stored by a semi-automated microscope. An operator reviewed those cells for their FISH signals. In 19 out of 20 CVS washings we found nucleated cells positive for HbE together with XY FISH signals. In none of the washings HbE positive cells with two X signals were found. Our results indicate that anti-HbE is a very specific antibody for identifying fetal NRBCs. NRBCs from CVS washings can be used as an additional fetal tissue for first trimester prenatal diagnosis.

Antibodies↗