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PubMed1996

Avian reovirus-induced syncytium formation is independent of infectious progeny virus production and enhances the rate, but is not essential, for virus-induced cytopathology and virus egress.

The nonenveloped avian reoviruses represent a distinct antigenic subgroup of orthoreoviruses. Unlike their mammalian counterparts, the avian reoviruses exhibit the unusual property of inducing rapid and extensive syncytium formation in cell cultures, a cytopathic effect more commonly associated with enveloped virus replication. While the syncytium-inducing capability of avian reovirus has been known for quite some time, the relationship between cell fusion and the virus replication cycle has not been determined. The conservation of the syncytial phenotype among all field isolates of avian reovirus suggests that avian reovirus-induced syncytium formation either reflects an essential step in the virus replication cycle involving intracellular membrane interactions or that cell fusion contributes to enhanced virus replication in infected animals. In order to distinguish between these possibilities, we have examined several aspects of virus replication in the presence of inhibitors of syncytium formation. Inhibitors of intracellular vesicle transport and O-linked glycosylation eliminated or markedly reduced syncytium formation with little effect on the rate or extent of virus macromolecular synthesis and infectious progeny virus production. Moreover, syncytium formation was not required for virus-induced cytopathology or virus egress but did significantly enhance the rate of both of these processes. The data indicate that, unlike the syncytium-inducing enveloped viruses, the membrane interactions and protein trafficking required for avian reovirus-induced syncytium formation do not reflect the sequelae of an essential step in the virus replication cycle. These results suggest that the conservation of the avian reovirus syncytial phenotype may reflect a fortuitous aspect of virus replication which confers advantages associated with the rapid spread of the virus within an infected host.

Animals↗
PubMed2001

Ophthalmologic heterogeneity in subjects with gyrate atrophy of choroid and retina harboring the L402P mutation of ornithine aminotransferase.

OBJECTIVE/PURPOSE: To investigate clinical variation in a genetically homogenous group of subjects with gyrate atrophy of choroid and retina with hyperornithinemia (GA). The group was made up of homozygotes and compound heterozygotes for mutation L402P in the ornithine aminotransferase (OAT) gene. DESIGN: Cross-sectional study. PARTICIPANTS: Thirty-five Finnish subjects (18 men) with GA with a mean age of 33 years (range, 5-74 years) carrying the Finnish founder mutation L402P. METHODS: All subjects were examined between 1993 and 1995. The analysis was composed of, in addition to careful clinical evaluation, studies of visual fields with Goldmann perimeter, photographing of the eye fundi, and corneal electroretinography (ERG) recordings. MAIN OUTCOME MEASURES: The changes in eye fundi, visual acuity, cataract changes in the lens, visual field constriction, and ERG responses were determined. RESULTS: Myopia, early cataracts, and highly abnormal ERG were typical for the GA subjects. The changes progressed rather uniformly with age. However, visual acuity, funduscopic findings, and visual fields showed great phenotypic variation. Despite the great interindividual variation, both eyes of each subject were always similarly affected. CONCLUSIONS: This study of 35 subjects with GA carrying a single mutation shows that the ophthalmologic symptoms and findings vary widely. The data also reveal that GA subjects are already affected by severe visual impairment in young adulthood. However, the diagnosis is often made very late.

Adolescent↗
PubMed1989

Clinical strains of Acinetobacter classified by DNA-DNA hybridization.

A collection of Acinetobacter strains consisting of 168 consecutive clinical strains and 30 type and reference strains was studied by DNA-DNA hybridization and a few phenotypic tests. The field strains could be allotted to 13 DNA groups. By means of reference strains ten of these could be identified with groups described by Bouvet & Grimont (1986), while three groups were new; they were given the numbers 13-15. The type strain of A. radioresistens--recently described by Nishimura et al. (1988)--was shown to be a member of DNA group 12, which comprised 31 clinical isolates. Of the 19 strains of A. junii, eight showed hemolytic activity on sheep and human blood agar and an additional four strains on human blood agar only. Strains of this species have previously been regarded as non-hemolytic. Reciprocal DNA pairing data for the reference strains of the DNA groups were treated by UPGMA clustering. The reference strains for A. calcoaceticus, A. baumannii and for DNA groups 3 and 13 formed a cluster with about 70% relatedness within the cluster. Other DNA groups joined at levels below 60%.

Acinetobacter↗
PubMed2004

Evaluating the genetic basis of multiple-locule fruit in a broad cross section of tomato cultivars.

Lycopersicon esculentum accessions bearing fasciated (multiloculed) fruit were characterized based on their flower organ and locule number phenotypes. Greenhouse and field evaluations indicate that increases in locule number are associated with increases in the number of other floral organs (e.g., sepals, petals, stamens) in all stocks. F1 complementation, F2 segregation analysis, and genetic mapping indicate that at least four loci account for increases in the number of carpels/locules in these stocks. The most significant of these map to the bottoms of chromosomes 2 and 11 and correspond to the locule number and fasciated loci. All stocks tested were fixed for mutations at the fasciated locus, which maps to the 0.5-cM interval between the markers T302 and cLET24J2A and occurs in at least three allelic forms (wild type and two mutants). One of the fasciated mutant alleles is associated with nonfused carpels and repressed recombination and may be due to a small inversion or deletion. The other two loci controlling locule number correspond to the lcn1.1 and lcn2.2 loci located on chromosomes 1 and 2, respectively.

Chromosome Mapping↗
PubMed2005

Phenotypic flexibility at the molecular and organismal level allows desert-dwelling rodents to cope with seasonal water availability.

We examined the phenotypic flexibility of field urine osmolality (Uosm) in response to seasonal rainfall and the experimental expression of renal aquaporins (AQPs) in the leaf-eared mouse Phyllotis darwini, a South American desert-dwelling rodent, through an integrative study at both the cellular and the organismal level. Field Uosm was higher in summer than in winter. Fall and winter Uosm were not significantly different. During a rainy year, winter Uosm was 2,140 +/- 82.3 mOsm kg(-1); the corresponding value in a dry year was 2,569 +/- 61.3 mOsm kg(-1). During the summer, the mean Uosm in a rainy year was 3,321 +/- 71.5 mOsm kg(-1), and in a dry year it was 3,604 +/- 107.2 mOsm kg(-1). The distribution of AQP-2, AQP-3, and AQP-4 was similar to that described for mouse and rat kidneys and confined to principal cells in cortex and inner medullary collecting-duct cells. AQP-4 immunoreactivity was unaltered by the state of water balance. Relative to water loading, dehydration induced an increase in AQP-2 immunoreactivity and protein abundance. Although more discrete, AQP-3 immunolabeling was also increased by dehydration. We now reveal how the integration of flexible renal mechanisms acting at the cellular and organismal level allow a small desert-dwelling mammal to cope with seasonal and yearly (El Nino) water availability in its semiarid habitat.

Acclimatization↗
PubMed1991

Dopaminergic innervation of the cerebral cortex: unexpected differences between rodents and primates.

Until recently, views on the organization and role of the mesotelencephalic dopaminergic (DA) systems were mostly based on studies of rodents, and it was assumed that homology existed across mammalian species. However, recent studies of both human and non-human primates indicate that this might not be so. The mesocortical DA system in primates, which is directly involved in the pathophysiology of severe illnesses such as Parkinson's disease and psychoses, shows substantial differences from that of rodents. These differences include much larger, re-organized terminal fields, a different phenotype for the co-localization of neuropeptides and a very early prenatal development.

Animals↗
PubMed2000

Cloning of a horn fly cDNA, HialphaE7, encoding an esterase whose transcript concentration is elevated in diazinon-resistant flies.

Reverse transcriptase-polymerase chain reaction (PCR) was used to clone two esterase cDNAs from a diazinon-resistant field population of horn flies that expresses qualitative and quantitative differences in esterases compared with a susceptible population. The open reading frame from one of the esterase cDNAs, HialphaE7, exhibits substantial amino-acid identity to an esterase associated with diazinon resistance in Lucilia cuprina. RNA Northern blots showed that HialphaE7 mRNA was more abundant in the diazinon-resistant population than the susceptible population. DNA copy number analysis did not reveal major differences in HialphaE7 gene copy number between the two populations. The full-length cDNA to HialphaE7 was cloned and sequenced, and found to contain all of the highly conserved sequence elements associated with carboxyl/cholinesterases. The HialphaE7 homologs in diazinon-resistant strains of L. cuprina and Musca domestica have been shown to possess an amino-acid substitution conferring diazinon hydrolytic activity to the esterase enzyme. This amino-acid substitution was not found in diazinon-resistant horn flies examined by allele-specific PCR. Individual flies from the resistant field population were phenotyped as diazinon-resistant or diazinon-susceptible by topical diazinon application bioassays and total RNA isolated and hybridized to HialphaE7 probe in ribonuclease protection assays. HialphaE7 transcript was expressed at a five-fold higher level in resistant female individual flies than in susceptible female individuals.

Amino Acid Sequence↗
PubMed2003

Cloning and characterization of the mating type (MAT) locus from Ascochyta rabiei (teleomorph: Didymella rabiei) and a MAT phylogeny of legume-associated Ascochyta spp.

Degenerate primers designed to correspond to conserved regions of the high mobility group (HMG) protein encoded by the MAT1-2 gene of Cochliobolus heterostrophus, Cochliobolus sativus, and Alternaria alternata were used to amplify the portion of the sequence corresponding to the HMG box motif from Ascochyta rabiei (teleomorph: Didymella rabiei). A combination of TAIL and inverse PCR extended the MAT1-2 sequence in both directions, then primers designed to MAT1-2 flanking DNA were used to amplify the entire MAT1-1 idiomorph. MAT1-1 and MAT1-2 idiomorphs were 2294 and 2693 bp in length, respectively, and each contained a single putative open reading frame (ORF) and intron similar to MAT loci of other loculoascomycete fungi. MAT genes were expressed at high levels in rich medium. MAT-specific PCR primers were designed for use in a multiplex PCR assay and MAT-specific PCR amplicons correlated perfectly to mating phenotype of 35 ascospore progeny from a cross of MAT1-1 by MAT1-2 isolates and to the mating phenotype of field-collected isolates from diverse geographic locations. MAT-specific PCR was used to rapidly determine the mating type of isolates of A. rabiei sampled from chickpea fields in the US Pacific Northwest. Mating type ratios were not significantly different from 1:1 among isolates sampled from two commercial chickpea fields consistent with the hypothesis that these A. rabiei populations were randomly mating. The mating type ratio among isolates sampled from an experimental chickpea field where asexual reproduction was enforced differed significantly from 1:1. A phylogeny estimated among legume-associated Ascochyta spp. and related loculoascocmycete fungi using sequence data from the nuclear ribosomal internal transcribed spacer (ITS) demonstrated the monophyly of Ascochyta/Didymella spp. associated with legumes but was insufficiently variable to differentiate isolates associated with different legume hosts. In contrast, sequences of the HMG region of MAT1-2 were substantially more variable, revealing seven well-supported clades that correlated to host of isolation. A. rabiei on chickpea is phylogenetically distant from other legume-associated Ascochyta spp. and the specific status of A. rabiei, A. lentis, A. pisi, and A. fabae was confirmed by the HMG phylogeny

Amino Acid Sequence↗
PubMed2002

Applying genetic approaches to the treatment of nicotine dependence.

To advance the science of tobacco control, an enhanced understanding of the bio-behavioral basis of nicotine addiction is needed. In this study, we provide an overview of data from investigations of genetic factors in smoking behavior, discuss potential bio-behavioral mechanisms and effect modifiers, and suggest avenues for pharmacogenetics research in the area of smoking cessation treatment. The evidence to date is very consistent with respect to the significance of genetic contributions to smoking behavior. However, attempts to elucidate the role of specific genetic variants have met with mixed success. Explanations for the lack of consistency in the results of genetic association studies include biases in ascertainment, ethnic admixture, lack of attention to co-variates or modifiers of genetic risk, and the need for more refined phenotypes. As the field of genetics and smoking research progresses, increasing attention is being devoted to gene-environment interactions, with particular attention to the identification of genetic variants that may modify the effects of pharmacological treatment for smoking. With advances in molecular biology and genomics technology, individualized tailoring of smoking cessation therapy to genotype is within our grasp. Such research has the potential to improve treatment outcome, thereby reducing morbidity and mortality from smoking-related disease.

Behavior Therapy↗
PubMed2005

Testosterone inhibits growth in juvenile male eastern fence lizards (Sceloporus undulatus): implications for energy allocation and sexual size dimorphism.

In the eastern fence lizard, Sceloporus undulatus, female-larger sexual size dimorphism develops because yearling females grow faster than males before first reproduction. This sexual growth divergence coincides with maturational increases in male aggression, movement, and ventral coloration, all of which are influenced by the sex steroid testosterone (T). These observations suggest that male growth may be constrained by energetic costs of activity and implicate T as a physiological regulator of this potential trade-off. To test this hypothesis, we used surgical castration and subsequent administration of exogenous T to alter the physiological and behavioral phenotypes of field-active males during the period of sexual growth divergence. As predicted, T inhibited male growth, while castration promoted long-term growth. Males treated with T also exhibited increased daily activity period, movement, and home range area. Food consumption did not differ among male treatments or sexes, suggesting that the inhibitory effects of T on growth are mediated by patterns of energy allocation rather than acquisition. On the basis of estimates derived from published data, we conclude that the energetic cost of increased daily activity period following T manipulation is sufficient to explain most (79%) of the associated reduction in growth. Further, growth may have been constrained by additional energetic costs of increased ectoparasite load following T manipulation. Similar studies of the proximate behavioral, ecological, and physiological mechanisms involved in growth regulation should greatly improve our understanding of sexual size dimorphism.

Analysis of Variance↗
PubMedDate not supplied

The GM2 gangliosidoses databases: allelic variation at the HEXA, HEXB, and GM2A gene loci.

The GM2 gangliosidoses are a group of recessive disorders characterized by accumulation of GM2 ganglioside in neuronal cells. The genes responsible for these disorders are HEXA (Tay-Sachs disease and variants), HEXB (Sandhoff disease and variants), and GM2A (AB variant of GM2 gangliosidosis). We report the establishment of three relational locus-specific databases recording allelic variation at the HEXA, HEXB, and GM2A genes and accessed at the GM2 gangliosidoses home page (http://data.mch.mcgill.ca/gm2-gangliosidoses). Submission forms are available for the addition of new mutations to the databases. The databases are available online for users to search and retrieve information about specific alleles by a number of fields describing mutations, phenotypes, or author(s).

Alleles↗
PubMed2005

Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae).

The importance of the cyanobacteria Prochlorococcus and Synechococcus in marine ecosystems in terms of abundance and primary production can be partially explained by ecotypic differentiation. Despite the dominance of eukaryotes within photosynthetic picoplankton in many areas a similar differentiation has never been evidenced for these organisms. Here we report distinct genetic [rDNA 18S and internal transcribed spacer (ITS) sequencing], karyotypic (pulsed-field gel electrophoresis), phenotypic (pigment composition) and physiological (light-limited growth rates) traits in 12 Ostreococcus strains (Prasinophyceae) isolated from various marine environments and depths, which suggest that the concept of ecotype could also be valid for eukaryotes. Internal transcribed spacer phylogeny grouped together four deep strains isolated between 90 m and 120 m depth from different geographical origins. Three deep strains displayed larger chromosomal bands, different chromosome hybridization patterns, and an additional chlorophyll (chl) c-like pigment. Furthermore, growth rates of deep strains show severe photo-inhibition at high light intensities, while surface strains do not grow at the lowest light intensities. These features strongly suggest distinct adaptation to environmental conditions encountered at surface and the bottom of the oceanic euphotic zone, reminiscent of that described in prokaryotes.

Chlorophyll↗
PubMed2003

Emergence of macrolide resistance in throat culture isolates of group a streptococci in Ontario, Canada, in 2001.

Of 500 group A streptococci isolated from pharyngeal swabs, 72 (14.4%) were macrolide resistant, compared to 2.1% in 1997. Of these, 66 (92%) were of the M phenotype and 6 (8.3%) were of the MLS phenotype. Pulsed-field gel electrophoresis found that two clones, with patterns identical to those of serotypes M1 and M4, accounted for 19.4 and 68.1% of the macrolide-resistant isolates, respectively.

Anti-Bacterial Agents↗
PubMed2001

Outbreak of vancomycin-resistant Enterococcus faecium of the phenotype VanB in a hospital in Warsaw, Poland: probable transmission of the resistance determinants into an endemic vancomycin-susceptible strain.

The first outbreak caused by vancomycin-resistant enterococci of the VanB phenotype in Poland was analyzed. It occurred in a single ward of a Warsaw hospital which is a specialized center for the treatment of hematological disorders. Between July 1999 and February 2000, 11 patients in the ward were found to be infected and/or colonized by Enterococcus faecium that was resistant in vitro to vancomycin and susceptible to teicoplanin. PCR analysis confirmed that the vancomycin-resistant E. faecium (VREM) isolates carried the vanB gene, which is responsible for the VanB phenotype. Pulsed-field gel electrophoresis (PFGE) typing revealed that the isolates belonged to four distinct PFGE types and that one of these was clearly predominant, including isolates collected from seven different patients. The isolates contained one or more copies of the vanB gene cluster of the identical, unique DraI/PagI (BspHI) restriction fragment length polymorphism type, which resided in either the same or different plasmid molecules or chromosomal regions. All this data suggested that the outbreak was due to both clonal spread of a single strain and horizontal transfer of resistance genes among nonrelated strains, which could be mediated by plasmids and/or by vanB gene cluster-containing transposons. The comparative analysis of vancomycin-susceptible E. faecium (VSEM) isolates collected from infections in the same ward at the time of the VREM outbreak has led to identification of a widespread VSEM strain that was possibly related to the major VREM clone. It is very likely that this endemic VSEM strain has acquired vancomycin-resistance determinants and that the acquisition occurred more than once during the outbreak.

Anti-Bacterial Agents↗
PubMed2003

Tbx5 and Tbx4 trigger limb initiation through activation of the Wnt/Fgf signaling cascade.

A tight loop between members of the fibroblast growth factor and the Wnt families plays a key role in the initiation of vertebrate limb development. We show for the first time that Tbx5 and Tbx4 are directly involved in this process. When dominant-negative forms of these Tbx genes were misexpressed in the chick prospective limb fields, a limbless phenotype arose with repression of both Wnt and Fgf genes By contrast, when Tbx5 and Tbx4 were misexpressed in the flank, an additional wing-like and an additional leg-like limbs were induced, respectively. This additional limb formation was accompanied by the induction of both Wnt and Fgf genes These results highlight the pivotal roles of Tbx5 and Tbx4 during limb initiation, specification of forelimb/hindlimb and evolution of tetrapod limbs, placing Tbx genes at the center of a highly conserved genetic program.

Animals↗
PubMed2005

An active surveillance study of vancomycin-resistant Enterococcus in Queen Elizabeth Hospital, Hong Kong.

OBJECTIVE: To assess the rate of faecal vancomycin-resistant Enterococcus colonisation in high-risk patients in a regional hospital. DESIGN: Prospective observational surveillance study. SETTING: Queen Elizabeth Hospital, Hong Kong. PATIENTS: From September 2001 to December 2002, stool samples from patients in the intensive care unit and patients in whom Clostridium difficile testing was requested were used for study using a broth enrichment method. MAIN OUTCOME MEASURES: Number of faecal vancomycin-resistant Enterococcus colonisation. RESULTS: A total of 2414 cultures from 1792 patients were tested for vancomycin-resistant Enterococcus using a broth enrichment method. Only one (0.06%) patient was found to harbour a vancomycin-resistant Enterococcus faecalis in the gastro-intestinal tract. Surveillance cultures from contacts of the case revealed another six with vancomycin-resistant Enterococcus faecalis. Vancomycin-resistant Enterococcus faecalis was also later reported from a clinical specimen (catheterized urine) of another patient. They were all epidemiologically linked to the index case. Mean inhibitory concentrations of vancomycin and teicoplanin were determined to be higher than 256 and 0.5 microgram/mL, respectively by E-test for all the vancomycin-resistant Enterococcus isolates. Polymerase chain reaction analysis confirmed the presence of vanB genes and the result was in line with the phenotype. Pulsed-field gel electrophoresis confirmed a monoclonal vancomycin-resistant Enterococcus outbreak. Strict infection control measures recommended by the Centers for Disease Control and Prevention were followed and the outbreak was successfully controlled. CONCLUSION: Vancomycin-resistant Enterococcus colonisation is rare, but present among high-risk patients in our hospital. A routine surveillance programme should be implemented that will enable early case detection and prompt initiation of infection control measures to prevent the emergence of an endemic situation.

Enterococcus faecalis↗
PubMed1999

A new method for haptoglobin phenotyping.

Haptoglobin is an acute-phase protein with three major phenotypes: Hp 1-1, Hp 2-1 and Hp 2-2. Studies have shown that functional differences between these phenotypes have important consequences in a number of pathological disorders (e.g. cardiovascular disease, autoimmune disorders, infectious disease), making phenotype determination of potential use in the clinical field. Previous methods for haptoglobin phenotyping have involved electrophoresis (starch, acetate and polyacrylamide gels) with phenotype visualization by peroxidase-sensitive stains that were often carcinogenic. Less hazardous immunoblotting and isoelectric focusing procedures are also available but the methods are lengthy, expensive and often complex. Here, we describe a new method for haptoglobin phenotyping using commercially available agarose gels and a non-carcinogenic stain (3,3',5,5'-tetramethylbenzidine). Our method showed 100% agreement with starch gel electrophoresis and reliably distinguished between commercial haptoglobin phenotype standards and serum samples from patients (n = 125). We obtained a sensitivity of 0.4 g/L for all phenotypes and the gels were stable for up to 2 months. This safer and easier to use method may permit increased access to knowledge of haptoglobin phenotype, allowing improved patient management and better tailoring of treatment in a variety of clinical conditions.

Electrophoresis, Agar Gel↗
PubMed2005

Biofilm formation is prevalent among field isolates of Actinobacillus pleuropneumoniae.

A total of 77 field isolates and 15 reference strains of the porcine respiratory pathogen Actinobacillus pleuropneumoniae were tested for their ability to form biofilms in a polystyrene microtiter plate assay. More than half of all field isolates, which included strains representing serotypes 1, 5 and 7, but only two reference strains (serotypes 5B and 11) exhibited biofilm formation. Strains that formed biofilms in microtiter plates also formed thick biofilms at the air-liquid interface when cultured in glass tubes with agitation. The biofilm formation phenotype was maintained indefinitely when cultures were passaged on agar but was lost after one or two passages in broth. Our findings indicate that biofilm formation is a prevalent phenotype among A. pleuropneumoniae field isolates, and that this phenotype may have been previously overlooked because of its tendency to be lost upon subculturing in broth. Biofilm formation may have relevance to the colonization, pathogenesis and transmission of this bacterium.

Actinobacillus Infections↗