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Use of a nonradioactive genetic probe identified, synthesized, and labeled in the polymerase chain reaction.

This study introduces a strategy to identify and produce sequences useful as genetic markers, or native genetic probes for DNA-DNA hybridization in bacterial strains where the genetics is not well described. Actinobacillus actinomy-cetemcomitans (A.a.) was used as an example. Fifty ng genomic DNA from A.a. ATCC 33384 and Haemophilus aphrophilus ATCC 33389 was amplified in a thermocycler using a single 10-mer primer. The PCR products were separated by electrophoresis on a 1% submarine agarose gel containing ethidium bromide and visualized by UV illumination, and the strain-specific amplitypes were compared. DNA from two bands, 0.9 and 4 kb, unique for the A.a. strain, was cut out, amplified under high stringency with the same primer and labeled by replacing 33.3 microM dTTP with digoxigenin-labeled dUTP in the reaction mixture. The labeled probe was then repeatedly used for hybridization to DNA from various A.a., H. aphrophilus, and other bacterial strains of the Pasteurellaceae family. The results showed that the 0.9-kb probe detected all A.a. tested, and distinguished it from other closely related bacterial species. We conclude that the described strategy is useful for identifying and selecting genetic sequences useful as genetic markers in A.a.

Adult↗

Molecular genetics of human blue cone monochromacy.

Blue cone monochromacy is a rare X-linked disorder of color vision characterized by the absence of both red and green cone sensitivities. In 12 of 12 families carrying this trait, alterations are observed in the red and green visual pigment gene cluster. The alterations fall into two classes. One class arose from the wild type by a two-step pathway consisting of unequal homologous recombination and point mutation. The second class arose by nonhomologous deletion of genomic DNA adjacent to the red and green pigment gene cluster. These deletions define a 579-base pair region that is located 4 kilobases upstream of the red pigment gene and 43 kilobases upstream of the nearest green pigment gene; this 579-base pair region is essential for the activity of both pigment genes.

Adolescent↗

Simultaneous visual detection of multiple viral amplicons by dipstick assay.

A sensitive, simple, and instrument-independent method for the visual detection and identification of multiple nucleic acid amplicons by dipstick has been developed. This method is based on nucleic acid hybridization on the dipstick membrane and a signal amplification system to allow visual detection. With hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) as model analytes, it is demonstrated that the visual dipstick test combined with multiplex reverse transcription (RT)-PCR for the amplification of viral nucleic acid provides a specific and sensitive detection method. The RT-PCR products were detected by the dipstick with an efficiency similar to that of a complex, expensive, and instrument-dependent method based on fluorogenic oligonucleotide probes. The detection limits of the dipstick combined with multiplex RT-PCR were 50, 125, and 500 IU/ml for HBV DNA, HCV RNA, and HIV-1 RNA, respectively. The dipstick assay detected with similar efficiencies amplicons derived from strains of HBV genotypes A through F, HCV genotypes 1 to 6, and HIV-1 subtypes A through H as well as CRF02 circulating recombinant forms of HIV-1. Analysis of 295 clinical samples and 19 pools of 10 plasma specimens from blood donors revealed that multiplex dipstick detection was reproducible, sensitive, and specific. The visual dipstick detection of multiple amplicons thus provides an attractive alternative to complex, instrument-dependent detection methods currently in use for nucleic acid testing. This new and sensitive method for nucleic acid detection should increase the availability of genomic screening in resource-limited settings and its applicability to near-patient testing.

DNA, Viral↗

Cloning and characterization of a papillomavirus associated with papillomas and carcinomas in the European harvest mouse (Micromys minutus).

Individuals in a colony of European harvest mice (Micromys minutus) were diagnosed with a variety of skin tumors including papillomas, trichoepitheliomas, and sebaceous carcinomas. Papillomavirus group-specific antigens and viruslike particles were detected in the papillomas. A 7.6-kilobase supercoiled circular DNA, which was cleaved once by EcoRI, was visualized in papilloma extracts by low-stringency Southern blot hybridization with a bovine papillomavirus type 2 probe. The molecule was cloned in pUC18, and a restriction map was generated. The molecule was shown to be colinear with the genome of human papillomavirus type 1a by partial sequence analysis. The DNA hybridized to human papillomavirus type 1a, rabbit oral papillomavirus, and the genome of Mastomys natalensis papillomavirus at Tm - 33 degrees C but not to the DNAs of 13 other papillomaviruses. Transformation of NIH 3T3 or C127I cells by tail papilloma extracts or transfected viral DNA was not observed. All 17 tumors examined contained large amounts of viral DNA in a supercoiled, unintegrated form as revealed by Southern blot hybridization. Furthermore, many extracts (25 of 35) from normal organs and skin of individuals with lesions elsewhere on their bodies contained viral DNA. This represents the first reported molecular cloning of a papillomavirus genome from a mouse species.

Animals↗

In vivo performance of a dual genetic marker, manA-gfp, in transgenic bentgrass.

A dual-marker combination, manA-gfp, comprising 2 independent expression cassettes of genes encoding an Escherichia coli phosphomannose isomerase (PMI) and a synthetic green fluorescent protein (GFP), was incorporated into the binary vector pPZP201. Agrobacterium tumefaciens-mediated transfer was used to introduce the manA-gfp into the mature-seed derived calli of Agrostis stoloifera L. 'Crenshaw'. The putative transgenic bentgrass calli were screened in Murashige and Skoog medium containing 15 g mannose/L, in conjunction with a visual examination of the GFP expression with a fluorescence stereomicroscope. Calli with GFP fluorescence grew well on the mannose selection media. A total of 24 transgenic plants derived from a single piece of callus lobe were studied for the genomic integration, expression, and function of the transgene. Genomic integration of the dual markers manA and gfp was confirmed by Southern blotting analysis, and the expression of manA also was validated by using PMI-specific antiserum. The inheritance and expression of the dual marker, manA-gfp, was demonstrated in the T1 generation. This study on the environmentally friendly markers further documented the feasibility of using alternative selection methods without using herbicide- or antibiotic-resistance markers.

Agrostis↗

Mapping multiple Quantitative Trait Loci by Bayesian classification.

We developed a classification approach to multiple quantitative trait loci (QTL) mapping built upon a Bayesian framework that incorporates the important prior information that most genotypic markers are not cotransmitted with a QTL or their QTL effects are negligible. The genetic effect of each marker is modeled using a three-component mixture prior with a class for markers having negligible effects and separate classes for markers having positive or negative effects on the trait. The posterior probability of a marker's classification provides a natural statistic for evaluating credibility of identified QTL. This approach performs well, especially with a large number of markers but a relatively small sample size. A heat map to visualize the results is proposed so as to allow investigators to be more or less conservative when identifying QTL. We validated the method using a well-characterized data set for barley heading values from the North American Barley Genome Mapping Project. Application of the method to a new data set revealed sex-specific QTL underlying differences in glucose-6-phosphate dehydrogenase enzyme activity between two Drosophila species. A simulation study demonstrated the power of this approach across levels of trait heritability and when marker data were sparse.

Animals↗

Transgenic mice expressing a functional human photopigment.

PURPOSE: Changes in retinal photopigments represent a fundamental step in the evolution of visual systems, in that addition of new pigment types or alterations in the spectral absorption properties of existing pigments modify visual capacities and thus open new visual worlds. To provide a tool that would allow direct examination of the changes caused by the presence of novel photopigments, this study was designed to determine whether a gene encoding a human cone photopigment introduced into the mouse genome would be expressed in a cone-specific manner and would support phototransduction. METHODS: Mice transgenic for the human long wavelength-sensitive (L) photopigment were generated by microinjection of fertilized mouse eggs. RNA expression in different tissues was monitored by reverse transcription-polymerase chain reaction analysis. Photopigment protein was localized in retinal cross sections and wholemounts by antibody staining. Light transduction of the cone photopigments was assessed by flicker photometric electroretinography (ERG). RESULTS: The human transgene was expressed specifically in the mouse cones in quantities comparable to those of the mouse middle wavelength-sensitive (M) pigment gene. Immunocytochemical analysis showed that the human L pigment was abundantly synthesized in most mouse cones, was translocated to the outer segments, and caused no detectable cone degeneration. Electroretinographic spectral sensitivity analysis showed that the human L pigment was efficient in eliciting an electrical response. The degree of expression of the transgene in the two founders correlated well with the spectral responsivity of the ERG. CONCLUSIONS: The human L photopigment transduces light efficiently in mouse cones, implying that all protein domains necessary for efficient interaction with intracellular transport and signal transduction machineries in mouse cones have been conserved through evolution. The expression of the human L photopigment gene in both classes of cone of the mouse retina indicates that the transgene did not have the regulatory elements necessary for restricting its expression to mouse M cones or that such elements are not recognized in mouse UV-sensitive cones.

Animals↗

Cloning and mapping of variety-specific rice genomic DNA sequences: amplified fragment length polymorphisms (AFLP) from silver-stained polyacrylamide gels.

An efficient technique for cloning DNA from silver-stained denaturing polyacrylamide gels was developed to allow the isolation of specific bands obtained from selective restriction fragment amplification (SRFA). This method proved as reliable as cloning radioactively labelled SRFA bands from the same gels. Rice DNA was used as a template, both with and without [32P]dCTP, using the same PCR profiles. Amplified products were separated using denaturing polyacryamide gel electrophoresis and visualized either by silver staining of gels or by autoradiography of 32P-labelled products. We cloned specific polymorphic SRFA bands directly from the denaturing polyacrylamide gels with one round of PCR amplification and confirmed that the sequences of the bands from silver-stained gels were identical to the corresponding 32P-labelled bands. The bands that were chosen represented amplified fragment length polymorphisms (AFLPs) between japonica and indica rice varieties. We studied the ability of two cloned AFLP bands to serve as heritable genetic markers by mapping them as RFLPs in an interspecific rice population and found that they represented single-copy DNA at unique loci in the rice genome.

Base Sequence↗

Efficient discovery of DNA polymorphisms in natural populations by Ecotilling.

We have adapted the mutation detection technology used in Targeting Induced Local Lesions in Genomes (TILLING) to the discovery of polymorphisms in natural populations. The genomic DNA of a queried individual is mixed with a reference DNA and used to amplify a target 1-kbp region of DNA with asymmetrically labeled fluorescent primers. After heating and annealing, heteroduplexes are nicked at mismatched sites by the endonuclease CEL I and cut strands are visualized using Li-cor gel analyzers. Putative polymorphisms detected in one fluorescence channel can be verified by appearance of the opposite cut strand in the other channel. We demonstrated the efficiency of this technology, called Ecotilling, by the discovery in 150+ individuals of 55 haplotypes in five genes, ranging from sequences differing by a single nucleotide polymorphism to those representing complex haplotypes. The discovered polymorphisms were confirmed by sequencing and included base-pair changes, small insertions and deletions, and variation in microsatellite repeat number. Ecotilling allows the rapid detection of variation in many individuals and is cost effective because only one individual for each haplotype needs to be sequenced. The technology is applicable to any organism including those that are heterozygous and polyploid.

DNA, Plant↗

Conserved and non-conserved loci of the glucagon gene in old world ruminating ungulates.

The homology and diversification of genomic sequence encoding glucagon gene among native Egyptian buffalos, camel and sheep were tested using cattle as model. Oligodeoxynucleotide primers designed from the available GenBank data were used for PCR probing of the glucagon gene encoding sequence at different loci. The DNA oligomer probes were constructed to flank either the whole gene encoding sequence or different intra-gene encoding sequences. The PCR products were visualized using agarose gel electrophoresis. All species showed a same size band of prepro-glucagon when PCR was used to amplify the whole gene encoding sequence. In contrary, amplifications of different intra-gene loci failed to give the same results. The results indicated variable degrees of diversity among old world ruminating ungulates in the glucagon gene encoding sequence. Compared with other ruminants, the variation appears predominantly in camel. Surprisingly, the similarity in size between both amplification products of whole gene encoding sequence and the proposed size of glucagon cDNA definitely excludes the possibility of large intervening introns spanning the genomic sequence of the glucagon gene in these species. This indicates that, in contrast to other tested mammals, the glucagon gene includes an essentially full-length copy of glucagon mRNA. The study revealed a possible new aspect of glucagon gene evolution in order to correlate its corresponding protein function among different ruminant species.

Amino Acid Sequence↗

GOLD.db: genomics of lipid-associated disorders database.

BACKGROUND: The GOLD.db (Genomics of Lipid-Associated Disorders Database) was developed to address the need for integrating disparate information on the function and properties of genes and their products that are particularly relevant to the biology, diagnosis management, treatment, and prevention of lipid-associated disorders. DESCRIPTION: The GOLD.db http://gold.tugraz.at provides a reference for pathways and information about the relevant genes and proteins in an efficiently organized way. The main focus was to provide biological pathways with image maps and visual pathway information for lipid metabolism and obesity-related research. This database provides also the possibility to map gene expression data individually to each pathway. Gene expression at different experimental conditions can be viewed sequentially in context of the pathway. Related large scale gene expression data sets were provided and can be searched for specific genes to integrate information regarding their expression levels in different studies and conditions. Analytic and data mining tools, reagents, protocols, references, and links to relevant genomic resources were included in the database. Finally, the usability of the database was demonstrated using an example about the regulation of Pten mRNA during adipocyte differentiation in the context of relevant pathways. CONCLUSIONS: The GOLD.db will be a valuable tool that allow researchers to efficiently analyze patterns of gene expression and to display them in a variety of useful and informative ways, allowing outside researchers to perform queries pertaining to gene expression results in the context of biological processes and pathways.

Adipocytes↗

[Development of an original computer program FISHMet: use for molecular cytogenetic diagnosis and genome mapping by fluorescent in situ hybridization (FISH)].

Original software FISHMet has been developed and tried for improving the efficiency of diagnosis of hereditary diseases caused by chromosome aberrations and for chromosome mapping by fluorescent in situ hybridization (FISH) method. The program allows creation and analysis of pseudocolor chromosome images and hybridization signals in the Windows 95 system, allows computer analysis and editing of the results of pseudocolor hybridization in situ, including successive imposition of initial black-and-white images created using fluorescent filters (blue, green, and red), and editing of each image individually or of a summary pseudocolor image in BMP, TIFF, and JPEG formats. Components of image computer analysis system (LOMO, Leitz Ortoplan, and Axioplan fluorescent microscopes, COHU 4910 and Sanyo VCB-3512P CCD cameras, Miro-Video, Scion LG-3 and VG-5 image capture maps, and Pentium 100 and Pentium 200 computers) and specialized software for image capture and visualization (Scion Image PC and Video-Cup) have been used with good results in the study.

Child↗

A method for the selective irradiation of part of a genome.

We developed a method for partial irradiation of cell nuclei and for highlighting the irradiated chromatin domain(s) in both interphase nuclei and metaphase chromosomes. The method involves the use of the replication program of chromosomes and consists of three major steps: I) selection of a suitable chromatin domain, II) damage induction by 125I, and III) visualization of the domain. Here, the first step of the method, applied to Chinese hamster HA-1 cells, is described. Using pulse labelling with the replication marker IUdR, it was shown that Xq does not replicate at early S-phase and that the replication timing of Xq can be highly effectively synchronized with hydroxyurea in a whole cell population. Thus, the replication timing of Xq may be used to exclude or to incorporate 125I into the Xq. Other chromatin can be selected and targeted with 125I in a similar way. Examples of possible applications of the method are given.

Animals↗

High-resolution mapping of the human 4q21 and the mouse 5E3 SCYB chemokine cluster by fiber-fluorescence in situ hybridization.

The CXC chemokine or small inducible cytokine B (SCYB) subfamily includes the T-cell chemoattractants MIG (CXCL9, SCYB9), IP-10 (CXCL10, SCYB10), and I-TAC (CXCL11, SCYB11). These three highly homologous chemokines lack the glutamic acid-leucine-arginine (ELR) motif and signal via the CXCR3 receptor. Previous work showed that the genes encoding these chemokines are localized in an individual mini-cluster on human Chromosome (Chr) 4 at position 4q21.2. Recently, we identified mouse Scyb11 and mapped this gene by fluorescence in situ hybridization (FISH) to mouse Chr 5E3, the orthologous locus to human 4q21 where the other two homologous mouse genes, Scyb9 and Scyb10, have also been localized. Since SCYB10 and SCYB11 are not represented in the recently published draft sequence of the human genome, we wanted to clarify exactly the order and distances of the three chemokine genes using two-color FISH on stretched DNA fiber preparations. Here, we report the simultaneous localization of all three genes and provide high-resolution visual maps of this chemokine cluster from both mouse and human. The three chemokine genes were found within a range of 32 kb on mouse and 29 kb on human DNA fiber targets. The precise physical distances were defined, and an almost identical arrangement of the human and mouse homologues was identified, indicating that this CXC chemokine mini-cluster has been completely conserved evolutionarily since the divergence of mouse and human. Our results refine previous maps of the three genes, support the hypothesis that they resulted from gene duplication that took place in a common ancestor of mouse and human, and provide complementary information on a region of the draft sequence of human Chr 4 that is not yet covered.

Animals↗

The ekeko mutant demonstrates a role for tetraspanin-like protein in plant development.

A new mutant with disturbed cell differentiation and severely altered plant morphology was obtained by visual screening of a T-DNA mutagenized population of Arabidopsis thaliana. The T-DNA in this mutant was inserted in an unknown gene (ORF At5g46700) located on chromosome V. This gene and additional 12 genes in the Arabidopsis genome show structural homologies to a class of abundantly expressed mammalian proteins with four transmembrane domains (TM4) called tetraspanins. In animals tetraspanins are involved in different cell functions like cell development, adhesion, motility, and differentiation, probably by organizing other proteins into a network of multimolecular membrane microdomains, called the tetraspanin web. So far no function for tetraspanins in plants has been described. Here, we show that a mutation in the TM4-like gene EKEKO results in severe developmental defects that could be the result of incorrect regulation of cell differentiation.

Amino Acid Sequence↗

Proteomics in living cells.

The study of protein dynamics in vivo is central to understanding the chemical machinery that makes up the process of life: in determining how, when, where and under what conditions proteins are created, form complexes, are modified and disintegrate. Until recently, facile methods to study these processes in intact living cells did not exist. This review describes promising experimental strategies that have been devised to visualize the dynamic nature of proteins and protein complex formation occurring in living cells. The approaches described are based largely on genetically encoded fusions to proteins of interest combined with labelling strategies. The feasibility of employing such strategies in genome-wide biochemical pathway mapping efforts is discussed.

Chemistry, Pharmaceutical↗

FISHing in the microwave: the easy way to preserve proteins. I. Colocalization of DNA probes and surface antigens in human leukocytes.

Most of the techniques for simultaneous visualization of proteic cell components and DNA probes are difficult to carry out. We have developed an alternative protocol for simultaneous visualization of DNA probes and cell surface antigens in human cells. The method exploits microwave energy to denature DNA and to anneal the probe after antigen fluorescent detection of unfixed cells previously embedded in a microgel. CD3 antigens and whole genome DNA probes or specific repetitive DNA sequences were colocalized in peripheral blood samples. The results show a strong, specific and consistent hybridization pattern in each cell that allowed correlation between cell subtype (PROTEINS) and nuclear phenotype (DNA).

CD3 Complex↗

HaploPainter: a tool for drawing pedigrees with complex haplotypes.

UNLABELLED: HaploPainter is a user-friendly pedigree-drawing application with special features for easy visualization of complex haplotype information. It has been developed to facilitate gene mapping in Mendelian diseases in terms of fast and reliable definition of the smallest critical interval harbouring the underlying gene defect. HaploPainter is written in Perl and may be used for visualization of haplotypes calculated by any of the common linkage programs. With special features like haplotype compression or the ability of marker section cut-out it particularly addresses the requirements for viewing large haplotypes as obtained by using for genome scans high-density marker panels of many thousands of single nucleotide polymorphisms (SNPs). AVAILABILITY: http://haplopainter.sourceforge.net/ CONTACT: holger.thiele@uni-koeln.de.

Chromosome Mapping↗