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At least 937 records · Page 52Linked to original sources
PubMed1997

[Molecular and genetic aspects of resistance to azoles in Candida albicans].

Fluconazole is one of the most useful drugs in the treatment of fungal systemic infections which frequently affect non immunocompetent individuals. However, the emergence of resistant strains in recent years may severely limit its usefulness in future. Although there are several described mechanisms involved in resistance to azoles, recent genetic studies demonstrate the role of specific genes in clinical resistance. Currently, the best characterized are the MDR1 and CDR1 genes, which code members of the MFS or ABC family of drug transporters, respectively. These proteins respond to the membrane potential (MFS) or hydrolyse ATP (ABC) thus promoting drug efflux and therefore reducing its intracellular accumulation. It has been shown that the mRNA from these genes is frequently increased in some Candida albicans resistant strains from patients receiving long term azole treatment. The development of molecular genetic tools in C. albicans is allowing characterization of their role in this and other important processes in the fungal cell.

English Abstract↗
PubMed2004

[Plant retrotransposons and their application].

Retrotransposons are one of the most unstable genetic elements in the plant kingdom, they have the potential to dramatically affect gene function and host genome structure. The current status of their types and structure, expression regulation, transposition, and evolution are reviewed. Their potential as genetic tools are also discussed.

Gene Expression Regulation, Plant↗
PubMed2006

Molecular characterization of Streptococcus suis strains by 16S-23S intergenic spacer polymerase chain reaction and restriction fragment length polymorphism analysis.

We developed a new molecular method of typing Streptococcus suis based on polymerase chain reaction (PCR) amplification of a large fragment of rRNA genes, including a part of the 16S and 23S genes and the 16S-23S intergenic spacer region (ISR), followed by restriction fragment length polymorphism (RFLP) analysis with RsaI or MboII endonuclease. The 16S-23S ISRs of 5 S. suis isolates were sequenced and compared. Size and sequence polymorphisms were observed between the S735 reference strain and the 4 wild-type strains. The genetic relationships between 138 independent S. suis strains belonging to various serotypes, isolated from swine or human cases, were determined. The discriminatory power of the method was > 0.95, the threshold value for interpreting typing results with confidence (0.954 with RsaI and 0.984 with RsaI plus MboII). The in vitro reproducibility was 100%. The strains isolated from humans were less genetically diverse than the strains isolated from pigs. For the first time, 2 molecular patterns (R6, M9) were significantly associated with S. suis serotype 2 strains. This genetic tool could be valuable in distinguishing individual isolates of S. suis during epidemiologic investigations.

Animals↗
PubMed1991

Nuclear location of synthetic oligonucleotides microinjected somatic cells: its implication in an antisense strategy.

Synthetic oligonucleotides are widely used to modulate gene expression. However their development as genetic tools and as molecule of therapeutic interest is restricted by the poor knowledge of their mechanism of action and of their uptake by cells. We recently found that microinjected oligonucleotides accumulates in the nucleus of the cells. These observations are described and their implications are discussed.

Animals↗
PubMed1998

Childhood tuberculosis: advances in immunopathogenesis, treatment and prevention.

Tuberculosis in childhood is an important cause of mortality worldwide. The disease is difficult to diagnose and the underlying immune mechanisms are poorly understood. Advances in the application of molecular genetic tools, as illustrated by the recent completion of the genome sequence of Mycobacterium tuberculosis, provide opportunities for the development of improved diagnostic tools and vaccines for tuberculosis. It is important that research efforts in this area should include consideration of the unique problems and possibilities related to the control of tuberculosis in children.

Journal Article↗
PubMed1988

Automated and rapid methods in clinical microbiology: past, present and future.

Instrument development in microbiology has focused on automating the traditional process of bacterial identification using growth-dependent technology. With the advent of genetic tools, advances in immunology, and engineering innovations microbiologists are moving away from the traditions of culture-dependent technology and are concentrating on the development of rapid, specific, nongrowth-dependent systems with a potential for automation.

Automation↗
PubMed1986

Perturbed pattern of catecholamine-containing neurons in mutant Drosophila deficient in the enzyme dopa decarboxylase.

We have initiated a study of catecholamine-containing neurons in Drosophila melanogaster because of the potential, with this organism, to perturb catecholamine metabolism using genetic tools. The major objectives of this study were (1) to define the pattern of catecholamine-containing neurons and (2) to determine the effect of the absence of dopa decarboxylase (DDC) enzyme activity on the catecholamine-containing neurons. We chose to analyze the catecholamine-containing neurons in the ventral ganglion of the larval CNS. To define the catecholamine-containing neurons, CNSs were dissected and reacted with glyoxylic acid. The catecholamine histofluorescence (CF) neuronal pattern (normal-CF neurons) in the wild-type ventral ganglion is stereotypic. In the mutant ventral ganglia, in the absence of DDC enzyme activity, most normal-CF neurons still exhibit CF, probably indicating the presence of accumulated L-dopa. Interestingly, in the mutant CNSs, additional novel neuronal subsets also exhibit CF. Analysis of CNSs from early developmental stages revealed that the novel-CF neurons become fluorogenic earlier than the normal-CF neurons in the mutant CNS. To determine whether neuronal subsets, in addition to the normal-CF, neurons are able to sequester catecholamines, CNSs from wild-type larvae were incubated in exogenous catecholamine (L-dopa or dopamine). Incubations in L-dopa or dopamine revealed normally nonfluorogenic neurons that are able to take up the amine and become fluorogenic. Among the neurons able to sequester L-dopa or dopamine are subsets that are similar to the novel-CF neurons in the mutant CNS. This similarity is best characterized by a major novel-CF neuronal cluster in the subesophageal-thoracic region. These results suggest that in the absence of DDC activity, subsets of normally nonfluorogenic neurons capable of sequestering L-dopa or dopamine accumulate the fluorogenic catecholamine. Hypotheses that might explain the mode of accumulation of the catecholamine within the novel-CF neurons are considered.

Animals↗
PubMed1995

[Hypercholesterolemia in children and young adults: should screening be done?].

Risk factors such as hypercholesterolemia, hypertension and smoking are already operative in children and during adolescence; it has been demonstrated that they favour the development of early atherosclerosis lesions in young adults. This fact poses the question of diagnosis and treatment of risk factors. There is still controversy whether hypercholesterolemia should be searched for by universal or by selective screening, or by no screening at all. Several professional organizations favour a selective screening strategy, i.e. determination of serum cholesterol if one parent has premature coronary heart disease (before age 55 yr) or if the family has familial hyperlipidemia, in particular familial hypercholesterolemia. This strategy is advocated here: cholesterol should be measured early, i.e. between age 6 and 8 yr. A total serum cholesterol of > 5.2 mmol/l is elevated (approx. 75th percentile) and should be further evaluated and possibly treated. The presence of familial hypercholesterolemia should be looked for in particular: such individuals can now be diagnosed with molecular genetic tools, and they are particularly prone to develop premature coronary heart disease. Treatment of hypercholesterolemia is mainly of a dietary nature, or possible with a bile acid binding resin (cholestyramine). Other drugs have not been sufficiently evaluated for efficacy and safety; they may be indicated in special cases such as patients with a very high risk. Young people with familial hypercholesterolemia should be particularly counselled to avoid other risk factors such as smoking.

Adolescent↗
PubMed1994

[Human major histocompatibility complex: the HLA system].

The HLA (human leukocyte antigens) system, or human major histocompatibility complex, is the most polymorphic functional genetic entity known at present. It consists of HLA class I genes and molecules (A, B and C) which control CD8+ cell-mediated antiviral responses, and class II genes and molecules (DR, DQ and DP) which control CD4+ cell responses (anti-bacterial and anti-toxin). HLA molecules function by presenting antigenic peptides to CD8+ cells (class I) and CD4+ cells (class II). Antigen presentation depends on the intracellular location of the antigen. Antigens present in the exocytosis pathway are presented by class I molecules, while class II molecules present antigens associated with the endocytosis pathway. More than 200 alleles have been detected by means of serological testing (microlymphocytotoxicity) and biochemical methods (IEF) in the HLA class I system, and now by means of molecular biology techniques for class II molecules (PCR-SSO and PCR-RFLP). This molecular typing has revealed the amino acids in HLA molecules that confer genetic susceptibility or resistance to numerous HLA-associated diseases. This is the case for example of ankylosing spondylitis (region 45-46 of HLA-B27 molecules), juvenile diabetes (aa 57 of D beta Q) and rheumatoid arthritis (aa 65-71 of DR beta). Thus, the HLA system is a genetic tool for diagnostic and therapeutic decision-making.

Animals↗
PubMed1993

[Perspectives of molecular genetics of hearing disorders].

In the last few years research efforts have succeeded in detectury the genetic background of several hereditary hearing disorders by molecular biological methods. The genetic code was been decoded for Neurofibromatosis types 1 and 2, as well as for such X-linked diseases as Alport's syndrome or Norrie's disease. Besides the classic genetic tools as chromosomal analysis, molecular biological techniques and methods have become important clinically for the ENT-specialist. In the present review we show the principles and applications of DNA-and RNA-analysis with hybridization techniques in Southern- and Northern-blot techniques, as well as in-situ hybridization and polymerase chain reaction (PCR). These molecular biological techniques will help improve the detection and analysis of hereditary inner ear disorders, but also be able to study in greater detail tumor carcinogenesis and mutagenesis. The various techniques are explained and the applications are demonstrated.

Chromosome Aberrations↗
PubMed1995

Clinical and molecular diagnosis of Alport syndrome.

Alport syndrome is an inherited disorder of collagen that affects the kidney, the eye, and the cochlea. The disease exhibits variability in its clinical and pathological manifestations, and is genetically heterogeneous. The X-linked dominant form of Alport syndrome arises from mutation in the COL4A5 gene, which encodes the alpha 5 chain of type IV collagen. The autosomal recessive form is caused by mutation in the COL4A3 gene, which encodes the alpha 3 chain of type IV collagen, or in the COL4A4 gene, which encodes the alpha 4 chain of type IV collagen. An autosomal dominant variety of Alport syndrome also exists, but mutations in this form of the disease have not yet been described. Cotransmission of X-linked dominant Alport syndrome and diffuse leiomyomatosis in some families results from deletions involving the COL4A5 gene and the contiguous COL4A6 gene. The clinical and pathologic features of Alport syndrome are attributable to abnormalities in the basement membrane collagen network composed of the alpha 3, alpha 4, and alpha 5 chains of type IV collagen, although the mechanism by which mutation in the gene encoding one of these chains effects the other two chains is not yet known. In addition, the processes that lead to progressive glomerular scarring and renal failure are incompletely understood. While diagnosis of Alport syndrome still rests on clinical and pathologic evaluation, immunohistochemical and molecular genetic tools can augment diagnostic precision.

Basement Membrane↗
PubMed1996

Development and organization of glial cells in Drosophila melanogaster.

Glial cells constitute a crucial component of the nervous system. They wrap the neuronal somata and axons and play a number of roles during normal neuronal development and activity as well as during axonal regeneration after wounding. The availability of cellular markers and genetic tools have made it possible in Drosophila to start identifying the genes and the cell-cell interactions leading to glial cell differentiation. The existence of multipotent precursor cells in the nervous system, the requirement for master genes determining the glial cell fate, the migratory abilities of fly glial cells and the existence of neuron-glial cell interactions during development are some of the features revealed by these approaches. These findings also indicate an evolutionary conservation in the developmental mechanisms between invertebrates and vertebrates. Finally, Drosophila is an ideal model system to determine in vivo the precise roles of glial cells and to study the etiology of pathologies associated with abnormal glial differentiation.

Animals↗
PubMed1997

Environmental epidemiology at the Medical Birth Registry of Norway; strengths and limitations.

A national registry of all pregnancy-outcomes was started in Norway. in 1967 to facilitate epidemiological surveillance. One aim was to detect increases in birth detect prevalences that was caused by new harmful exposures. Over the years several studies of unexpected time-trends and regional differences have been performed, but specific harmful exposures have so far not been detected. In a study of possible effects of the Chernobyl fallout, the registry enabled a detailed investigation of a possible increase in prevalence of birth detects that occurred specifically in the most exposed areas of Norway. The strength of this approach was the population coverage of the registry, while important limitations were incomplete reporting (outcome misclassification) and crude exposure information (exposure misclassification). While still taking advantage of the population coverage of the medical birth registry, a new generation of studies with more complete case ascertainment and individual exposure information are being prepared. One particularly interesting new option is to use molecular genetic tools to identity susceptible mothers or children. Collection and storage of biological specimens on a large scale is challenging, but in the search for gene-environment interactions, population-based studies are particularly attractive.

Congenital Abnormalities↗
PubMed1998

[The yeast genome].

The yeast genome has been completed and the almost 6000 proteins from the yeast proteome are under analysis. This analysis will contribute to elucidate the basic mechanisms of unicellular eucaryotic life. Several aspects of such studies are relevant to human health problems. In particular, it should allow the development of new fungicides which would be more efficient and specific and would escape the complex multidrug cell export systems developed by pathogenic fungi. Also several human genes determining hereditary diseases have yeast homologues. The function of these homologues can be determined using a series of genetic tools which are unique to yeast. These human genes can also be expressed in yeast and be submitted to the same tools. Several examples of these approaches will be chosen concerning yeast homologues of human membrane proteins belonging to ion channels, permeases, cation transport-ATPases or ABC transporters superfamilies.

Animals↗
PubMed2002

Ingeneue: a versatile tool for reconstituting genetic networks, with examples from the segment polarity network.

Here we describe a software tool for synthesizing molecular genetic data into models of genetic networks. Our software program Ingeneue, written in Java, lets the user quickly turn a map of a genetic network into a dynamical model consisting of a set of ordinary differential equations. We developed Ingeneue as part of an ongoing effort to explore the design and evolvability of genetic networks. Ingeneue has three principal advantages over other available mathematical software: it automates instantiation of the same network model in each cell in a 2-D sheet of cells; it constructs model equations from pre-made building blocks corresponding to common biochemical processes; and it automates searches through parameter space, sensitivity analyses, and other common tasks. Here we discuss the structure of the software and some of the issues we have dealt with. We conclude with some examples of results we have achieved with Ingeneue for the Drosophila segment polarity network.

Animals↗
PubMed1993

Bi- and multivariate analyses of diallel crosses: a tool for the genetic dissection of neurobehavioral phenotypes.

The genetic-correlational approach provides a very powerful tool for the analysis of causal relationships between phenotypes. It appears to be particularly appropriate for investigating the functional organization of behavior and/or causal relationships between brain and behavior. A method for the bivariate analysis of diallel crosses that permits the estimation of correlations due to environmental effects, additive-genetic effects, and/or dominance deviations is described, together with a worked-out example stemming from a five times replicated 4 x 4 diallel cross between inbred mouse strains. The phenotypes chosen to illustrate the analysis were locomotor activity and rearing frequency in an open field. Large, positive additive-genetic and dominance correlations between these two phenotypes were obtained. This finding was replicated in another, independently executed, diallel cross.

Alleles↗
PubMed1997

Genome surfing: using internet-based informatic tools toward functional genetic studies in mouse and humans.

The wealth of databases containing genomic information and the easy access via the internet can be an invaluable tool in performing genetic studies and identifying important sequences. This article provides an overview and specific methods for using these resources in both positional cloning and identifying candidate genes for diseases and phenotypes. The ability to apply information across the mouse and human species is stressed. Useful internet sites and their contents are identified and described, and some understanding of their current limitations is provided. As additional genomic definition accelerates, the use of these tools will become more essential in cutting edge research linking sequence and function in whole mammalian organisms.

Animals↗
PubMed2002

Ability of the hydrophobic FGF and basic TAT peptides to promote cellular uptake of recombinant Cre recombinase: a tool for efficient genetic engineering of mammalian genomes.

Conditional mutagenesis is a powerful tool to analyze gene functions in mammalian cells. The site-specific recombinase Cre can be used to recombine loxP-modified alleles under temporal and spatial control. However, the efficient delivery of biologically active Cre recombinase to living cells represents a limiting factor. In this study we compared the potential of a hydrophobic peptide modified from Kaposi fibroblast growth factor with a basic peptide derived from HIV-TAT to promote cellular uptake of recombinant Cre. We present the production and characterization of a Cre protein that enters mammalian cells and subsequently performs recombination with high efficiency in a time- and concentration-dependent manner. Histidine-tagged Cre recombinase transduced inefficiently unless fused to a nuclear localization signal (NLS). Fusion of NLS-Cre to the fibroblast growth factor transduction peptide did not improve the transducibility, whereas fusion with the TAT peptide significantly enhanced cellular uptake and subsequent recombination. More than 95% recombination efficiency in fibroblast cells, as well as murine embryonic stem cells, was achieved after His-TAT-NLS-Cre transduction. Efficient recombination could also be obtained in primary splenocytes ex vivo. We expect that application of His-TAT-NLS-Cre, which can be produced readily in large quantities from a bacterial source, will expand our abilities to manipulate mammalian genomes.

Cells, Cultured↗