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L J Ward

Publications and source records attributed to L J Ward.

At least 37 records · Page 2Linked to original sources
PubMed1993

Insertion sequence analysis of protoplast fused strains of Lactococcus lactis ssp. cremoris.

The use of insertion sequence probes for the analysis of fusants obtained following protoplast fusion is described. Hybridization of both total and plasmid DNA from parent and fusant strains with probes to IS904 and ISS1 showed that of the four protoplast fusions examined, three appeared to involve a rearrangement of genetic material while in the fourth the fusant appeared similar to one of the parental strains. This method of analysis provides more information about the changes induced by protoplast fusion than that obtained by monitoring the acquisition or loss of individual characteristics.

Base Sequence↗
PubMed1993

Temporally Regulated Transcriptional Expression of the Genomes of Lactococcal Bacteriophages c2 and sk1.

Transcription maps of the Lactococcus lactis subsp. lactis prolate phage c2 and small isometric phage sk1 were constructed. Early and late transcripts were demonstrated in phage c2. Early transcription was localized to within a 7.5-kb EcoRV fragment, and late transcription included the region which encodes the phage structural proteins and a lysin gene. Early, middle, and late transcripts were demonstrated in phage sk1. Transcription was confined to an 11.3-kb region defined by the three EcoRV restriction fragments of 6.2, 4.7, and 0.46 kb during the early part of the sk1 life cycle. Middle gene transcripts extended from the EcoRV site (defining the left-hand limit of early gene expression) through the cos site and included the 4.3-kb PvuII-cos fragment. Late transcription was detected over the remainder of the phage genome. These results indicated that gene expression was temporally regulated at the level of transcription in these two lactococcal phages and that two regions of time-dependent transcription exist in phage c2 and three in phage sk1.

Journal Article↗
PubMed1993

Sequence analysis of the lysin gene region of the prolate lactococcal bacteriophage c2.

Approximately 80% of the genome of the prolate-headed lactococcal bacteriophage c2 was cloned into shuttle vectors pSA3 and pFX3 in Escherichia coli and transferred to Lactococcus lactis. A 1.67-kilobase EcoRV fragment containing the gene for the phage lysin was identified and the position and orientation of the phage lysin gene in the physical map of the phage were determined. The phage lysin was expressed in E. coli and its sequence was determined and compared with the sequences of other bacteriophage lytic genes. The sequence was similar, but not identical, to that of the related lactococcal phage m13, having a number of silent substitutions and an apparent deletion that altered the carboxy terminus of the protein. Possible alternative translation initiation codons for the lysin gene and two possible alternative mechanisms for access of the lysin enzyme to the cell wall are discussed. An open reading frame upstream of the putative lysin gene was found to be 177 base pairs longer than that reported for phage m13. A codon usage table for the lysin genes of several phages as well as for reported gene sequences from L. lactis and lactococcal bacteriophages is presented.

Amino Acid Sequence↗
PubMed1991

Tight linkage of the gene for spinocerebellar ataxia to D6S89 on the short arm of chromosome 6 in a kindred for which close linkage to both HLA and F13A1 is excluded.

A locus for an autosomal dominant form of spinocerebellar ataxia (SCA1) has been assigned to the short arm of chromosome 6 on the basis of linkage to the major histocompatibility system (HLA). In this study of a five-generation American black family, close linkage between the disease locus and both HLA and the coagulation factor XIIIA (F13A1) locus was excluded, and lod scores for all locations of the disease locus between HLA and F13A1 were less than -1.4. These results suggest that the locus causing spinocerebellar ataxia in this family is not in this region. However, the disease locus was found to be closely linked to a microsatellite polymorphism, D6S89, which is between HLA and F13A1. The maximum lod score for SCA1 and D6S89 is 4.90 at a recombination fraction of 0, both in males and in females. These data show that exclusion of close linkage to the HLA complex and F13A1 in a kindred with spinocerebellar ataxia does not rule out the possibility that the disease locus in that family is on 6p. Accordingly, all families segregating a dominantly inherited ataxia should be evaluated for linkage to D6S89, to determine whether the locus causing the disease is SCA1.

Adolescent↗
PubMed1990

Gametic equilibrium between 24 polymorphic markers.

Pairs of unlinked genetic markers (blood cell antigens and enzymes and serum proteins) were tested for gametic equilibrium (GE) in data from 508 unrelated individuals from different regions of North America. A total of 24 markers were considered in the study. Only 14 of 262 pairs (5.3%) of markers deviated from GE at the 5% significance level and only 6 pairs (2.3%) remained in significant disequilibrium after accounting for genetic heterogeneity among regional groups. The particular combinations of alleles or one-locus genotypes that showed significant association were identified in case they might be replicated in future studies. On the basis of this study alone, however, there is no reason to suspect disequilibrium between the pairs of markers studied.

Alleles↗
PubMed1989

"Acadian" and "classical" forms of Friedreich ataxia are most probably caused by mutations at the same locus.

"Acadian ataxia" is a form of Friedreich ataxia found in individuals of Acadian ancestry. It was described by Barbeau (in Sobue I (ed): Spinocerebellar Degeneration; Tokyo: Univ. Tokyo Press, pp 121-142, 1980) as having a slower course of degeneration and less severe secondary symptoms than "classical" Friedreich ataxia. He suggested that these 2 forms of the disease may be distinct. The mutation causing "classical" Friedreich ataxia has recently been mapped to chromosome 9 through genetic linkage studies, and here we show that the locus causing Friedreich ataxia in Acadian families from southwestern Louisiana is tightly linked to the same DNA marker, D9S15. Thus, these 2 disorders, which may be differentiated clinically, are most probably due to mutation(s) at the same locus on chromosome 9.

Chromosome Mapping↗
PubMed1989

Expression by Soil Bacteria of Nodulation Genes from Rhizobium leguminosarum biovar trifolii.

Gram-negative, rod-shaped bacteria from the soil of white clover-ryegrass pastures were screened for their ability to nodulate white clover (Trifolium repens) cultivar Grasslands Huia and for DNA homology with genomic DNA from Rhizobium leguminosarum biovar trifolii ICMP2668 (NZP582). Of these strains, 3.2% were able to hybridize with strain ICMP2668 and nodulate white clover and approximately 19% hybridized but were unable to nodulate. Strains which nodulated but did not hybridize with strain ICMP2668 were not detected. DNA from R. leguminosarum biovar trifolii (strain PN165) cured of its symbiotic (Sym) plasmid and a specific nod probe were used to show that the relationship observed was usually due to chromosomal homology. Plasmid pPN1, a cointegrate of the broad-host-range plasmid R68.45 and a symbiotic plasmid pRtr514a, was transferred by conjugation to representative strains of nonnodulating, gram-negative, rod-shaped soil bacteria. Transconjugants which formed nodules were obtained from 6 of 18 (33%) strains whose DNA hybridized with that of PN165 and 1 of 9 (11%) strains containing DNA which did not hybridize with that of PN165. The presence and location of R68.45 and nod genes was confirmed in transconjugants from three of the strains which formed nodules. Similarly, a pLAFR1 cosmid containing nod genes from a derivative of R. leguminosarum biovar trifolii NZP514 formed nodules when transferred to soil bacteria.

Journal Article↗
PubMed1989

Characterization of a monoclonal antibody against active pectate lyase from Erwinia carotovora.

A monoclonal antibody (2E2) produced against pectate lyase from Erwinia carotovora ssp. carotovora reacted with a 41- and a 44-kilodaltion protein on Western blots of concentrated Erwinia culture supernatants resolved by sodium dodecyl sulfate - polyacrylamide gel electrophoresis. It was unequivocally shown that monoclonal 2E2 reacted with an active form of pectate lyase by affinity purifying the antigen with the monoclonal. The affinity-purified antigen was enzymatically active and moved as a single protein band in a nonequilibrium isoelectric focusing gel. Monoclonal 2E2 reacted with the pectate lyases of a diverse range of E. carotovora ssp. carotovora, ssp. atroseptica, and ssp. betavasculorum strains, as well as with one of three strains of E. chrysanthemi. The electrophoretic mobility of the major protein (44 kilodaltons) that reacted with 2E2 was identical within a subspecies but differed among subspecies.

Antibodies, Bacterial↗
PubMed1987

A linkage study of panic disorder.

We tested for linkage between panic disorder and a battery of 29 genetic markers in 26 families. Linkage between panic disorder and 18 of the marker loci could be excluded at a recombination fraction of 0.00, nine at a recombination fraction of 0.05, and four at a recombination fraction of 0.10. The 18 loci are distributed over ten chromosomes. One locus was suggestive of linkage. The maximum lod score for alpha-haptoglobin was 2.27 at a recombination fraction of 0.0, representing odds in favor of linkage of 186.1. alpha-Haptoglobin has been mapped to chromosome 16q22. The results demonstrate that linkage studies of psychiatric disorders can yield informative results by identifying tentative linkages that merit further investigation and by excluding regions of the genome from future linkage searches.

Adult↗
PubMed1987

Linkage and segregation analyses of apolipoproteins A1 and B, and lipoprotein cholesterol levels in a large pedigree with excess coronary heart disease: the Bogalusa Heart Study.

Robust methods were employed, using data from a single large pedigree, to screen serum apolipoprotein A1 and B levels, serum lipoprotein cholesterol levels, and ratios of serum lipoprotein cholesterol fractions to apolipoprotein A1 and B levels for genetic linkage to 31 polymorphic markers. Segregation analyses were performed for each of the apolipoprotein and lipoprotein cholesterol fractions to obtain estimates for use in applying likelihood methods of linkage analysis. Trait-marker combinations for which linkages were suggested from the robust methods were then reexamined for linkage using the likelihood (lod score) method. Results from the segregation analyses were consistent with major gene determination of apo B and HDL-C levels, the HDL-C to apo A1 ratio, the LDL-C to apo B ratio, and a measure of relative content of cholesterol in HDL-C and LDL-C. Linkage between haptoglobin and the HDL-C/apo A1 ratio was suggested, with a lod score of 1.72 at theta = 0.05.

Apolipoprotein A-I↗
PubMed1987

Association between polymorphic blood markers and risk factors for cardiovascular disease in a large pedigree.

A large pedigree with high prevalence of heart disease is investigated to analyse the association between polymorphic blood markers and quantitative risk factors for cardiovascular disease. The analysis incorporates a familial correlation structure among the individuals in the pedigree and a generalized power transformation to induce approximate residual normality of the risk factors. A total of 380 marker/risk factor combinations are analysed, and at the normal 1% significance level, positive associations are found between the A antigen of the ABO locus and both serum total cholesterol and low-density lipoprotein cholesterol, and negative associations are found between the B antigen of the ABO locus and serum total cholesterol, and between the B allele of acid phosphatase (AP) locus and systolic blood pressure.

ABO Blood-Group System↗
PubMed1987

Linkage studies of Friedreich ataxia by means of blood-group and protein markers.

Friedreich ataxia (FA) is an autosomal recessive, neuro-degenerative disorder in which the pathogenetic mechanism remains unidentified despite extensive biochemical studies. Genetic-linkage studies provide an alternative approach to determining the basic defect. Linkage analysis between FA and 36 polymorphic-blood-group and protein markers has been carried out on three separate patient populations--16 families from the inbred Acadian population of Louisiana, 21 French-Canadian families from Quebec, and nine apparently unrelated British families--in an attempt to determine the chromosomal location of the disease mutation. Neither evidence of linkage to any of the markers investigated nor heterogeneity among the populations was found for any of the comparisons. The negative lod scores exclude the locus for FA from greater than 20% of the genome.

Blood Group Antigens↗
PubMed1985

Intracellular processing of the Newcastle disease virus fusion glycoprotein.

The fusion glycoprotein (Fo) of Newcastle disease virus is cleaved at an intracellular site (Nagai et al., Virology 69:523-538, 1976) into F1 and F2. This result was confirmed by comparing the transit time of the fusion protein to the cell surface with the time course of cleavage of Fo. The time required for cleavage of half of the pulse-labeled Fo protein is ca. 40 min faster than the half time of the transit of the fusion protein to the cell surface. To determine the cell compartment in which cleavage occurs, use was made of inhibitors which block glycoprotein migration at specific points and posttranslational modifications known to occur in specific cell membranes. Cleavage of Fo is inhibited by carbonyl cyanide m-chlorophenylhydrazone; thus, cleavage does not occur in the rough endoplasmic reticulum. Monensin blocks the incorporation of Newcastle disease virus glycoproteins into virions and blocks the cleavage of the fusion glycoprotein. However, Fo cannot be radioactively labeled with [3H] fucose, whereas F1 is readily labeled. These results argue that cleavage occurs in the trans Golgi membranes or in a cell compartment occupied by glycoproteins quite soon after their transit through the trans Golgi membranes. The implications of the results presented for the transit times of the fusion protein between subcellular organelles are discussed.

Animals↗
PubMed1985

PGM1 null allele detected in a Caucasian mother-son pair.

The presence of a PGM1 null allele in a mother and her son was deduced from their inconsistent phenotypes. Quantitation studies were done to confirm the half-normal enzyme activity. Phenotype analysis of 29 additional genetic markers gave no indication of non-parentage, making non-maternity a very unlikely explanation for the discrepancy.

Alleles↗
PubMed1984

Linkage relationships between a major gene for catechol-o-methyltransferase activity and 25 polymorphic marker systems.

Segregation analysis has provided evidence suggesting the existence of a major gene for catechol-o-methyltransferase (COMT) activity in man. Five large families (4 Caucasian, 1 black), with a total of 1,189 individuals, were ascertained as part of a genetic study of blood pressure. Erythrocyte COMT activity and status at 25 polymorphic genetic marker loci were determined on more than 518 individuals in these pedigrees. Genetic linkage analysis of COMT with each of the 25 marker loci was performed in two ways: 1) using parameter estimates from segregation analysis of untransformed COMT activity, and 2) using parameter estimates from segregation analysis of the power transformation of the COMT activity that maximized the likelihood of the genetic hypothesis in each family. Tight and close linkage were excluded at 21 and 15 loci, respectively. A lod score of 1.27 at theta = 0.1 was found between the loci for COMT activity and phosphogluconate dehydrogenase (PGD). Transformation of the data had little effect on the outcome of the linkage analysis.

Catechol O-Methyltransferase↗