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D B Wilson

Publications and source records attributed to D B Wilson.

At least 109 records · Page 6Linked to original sources
PubMed1995

Assignment of the transcription factor GATA4 gene to human chromosome 8 and mouse chromosome 14: Gata4 is a candidate gene for Ds (disorganization).

We report the mapping of the human and mouse genes for transcription factor GATA-4, a newly identified member of DNA-binding proteins involved in lineage determination. The human GATA4 gene was assigned to the short arm of human chromosome 8 using genomic DNAs from human-rodent somatic cell hybrid lines. Southern blot analyses indicated the presence of a human-specific 7.6-kb fragment that was observed only in DNA from the hybrid cells containing human chromosome 8 or the proximal region of its short arm. The mouse Gata4 gene was mapped to chromosome 14, closely linked to Clu (clusterin), using genomic DNAs from a (C57BL/6J x Mus spretus)F1 x M. spretus backcross. This mapping assignment places the Gata4 gene in the vicinity of the mouse Ds (disorganization) locus, a dominant gain-of-function mutation affecting embryonic development. We speculate that Ds is caused by a mutation in the Gata4 gene, ectopic expression of GATA-4, or a mutation in another lineage determination gene closely linked to Gata4.

Abnormalities, Multiple↗
PubMed1995

Regulation of J6 gene expression by transcription factor GATA-4.

Retinoic acid-induced differentiation of mouse F9 embryonal carcinoma cells into primitive endoderm is accompanied by increased transcription of the gene for J6, a heat shock protein implicated in collagen biosynthesis. In this paper we present evidence that transcription factor GATA-4, a retinoic acid-inducible GATA-binding protein, is involved in the regulation of J6 gene expression in F9 cells. Northern-blot analysis indicates that transcripts encoding GATA-4 and J6 increase in parallel during retinoic acid-induced differentiation of F9 cells. Gel-shift experiments and antibody binding studies demonstrate that: (1) GATA-4 is the major GATA-binding protein activity in differentiated F9 cells, and (2) GATA-4 binds to consensus GATA motifs in the retinoic acid-responsive portion of the J6 promoter. Co-transfection studies using NIH 3T3 cells show that GATA-4 is a potent trans-activator of the J6 promoter. These lines of evidence suggest that expression of J6 in F9 cells is regulated by GATA-4. We speculate that transcription factor GATA-4 may also control other genes involved in extracellular matrix formation in the yolk sac.

3T3 Cells↗
PubMed1995

Characterization of a Thermomonospora fusca exocellulase.

The exocellulase E3 gene was cloned on a 7.1 kb NotI fragment from Thermomonospora fusca genomic DNA into Escherichia coli and expressed in Streptomyces lividans. The E3 gene was sequenced and encoded a 596 residue peptide. The molecular masses of the native and cloned E3s were determined by mass spectrometry, and the value for E. coli E3, 59,797 Da, agreed well with that predicted from the DNA sequence, 59,646 Da. The value of 61,200 Da for T. fusca E3 is consistent with E3 being a glycoprotein. E3 is thermostable, retaining full activity after 16 h at 55 degrees C. It also has a broad pH optimum around 7-8, retaining 90% of its maximal activity between pH 6 and 10. The cloned E3s were identical to the native enzyme in their activity, cellulose binding, and thermostability. Papain digestion produced a 45.7 kDa catalytic domain with 77% of the native activity on amorphous cellulose and 33% on crystalline cellulose. E3 belongs to cellulase family B and retains the residues that have been identified to be crucial for catalytic activity in Trichoderma reesei cellobiohydrolase II and T. fusca E2. The E3 gene contains a 14 bp inverted repeat regulatory sequence 212 bp before the translational start codon instead of the 30-70 bp found for the other T. fusca cellulase genes. An additional copy of this sequence with one base changed is 314 bp before the translational start codon. The transcriptional start site of the E3 gene was shown to be between these two inverted repeats.

Actinomycetales↗
PubMed1995

The effect of carbohydrates on the expression of the Prevotella ruminicola 1,4-beta-D-endoglucanase.

The beta-1,4-endoglucanase of the ruminal bacterium, Prevotella ruminicola B14, hydrolysed carboxymethylcellulose and barley glucan but not xylan or mannan. Endoglucanase activity was present in 88- and 82-kDa proteins, and there was at least a 20-fold variation in endoglucanase activity when P. ruminicola B14 was grown on different sugars. The highest activities were observed with mannose, cellobiose or xylose and little activity was observed with sucrose, arabinose or rhamnose, P. ruminicola B14 also had significant xylanase and mannanase activities, but these activities were present in proteins that had lower molecular masses than the endoglucanase and these proteins did not cross-react with antibody made against the endoglucanase. Mannanase activity has a similar pattern of expression to the endoglucanase, while the xylanase was not induced or repressed by the same sugars or combinations of sugars. The xylanase activity was greatest when xylan was the energy source for growth, but xylose was a very poor inducer of xylanase activity.

Animals↗
PubMed1995

The GATA-4 transcription factor transactivates the cardiac-specific troponin C promoter-enhancer in non-muscle cells.

The unique contractile phenotype of cardiac myocytes is determined by the expression of a set of cardiac-specific genes. By analogy to other mammalian developmental systems, it is likely that the coordinate expression of cardiac genes is controlled by lineage-specific transcription factors that interact with promoter and enhancer elements in the transcriptional regulatory regions of these genes. Here, we demonstrate that the slow/cardiac-specific troponin C (cTnC) enhancer contains a specific binding site for the lineage-restricted, zinc finger transcription factor, GATA-4 and that GATA-4 mRNA and protein is expressed in cardiac myocytes. In addition, GATA-4 binding sites were identified in several previously characterized cardiac-specific transcriptional regulatory elements. The cTnC GATA-4 binding site is required for transcriptional enhancer activity in primary cardiac myocytes. Moreover, the cTnC enhancer can be transactivated by over-expression of GATA-4 in non-cardiac muscle cells such as NIH 3T3 cells. Taken together, these results are consistent with a model in which GATA-4 functions to direct tissue-specific gene expression during mammalian cardiac development.

3T3 Cells↗
PubMed1995

Acute and subacute rehabilitation for stroke: a comparison.

Subacute rehabilitation, a recent innovation, is a less intense form of traditional inpatient rehabilitation. This study is a retrospective comparison of stroke treatment in a comprehensive inpatient service (acute rehabilitation) and subacute rehabilitation in a skilled nursing facility. Consecutive records during 1990 and 1991 resulted in 331 patients at the acute level and 97 at the subacute. Analysis of patient characteristics found few major differences between the two populations. Scrutiny of billing records found that acute program patients had twice as much treatment during a stay, twice the daily treatment hours, and twice the average charge per day. Acute rehabilitation patients showed substantially greater gains in functional impairment measures (FIM), but the proportion of patients discharged to the community varied little. Cost-effectiveness analysis found that the charge per successful discharge was more than double for acute rehabilitation. The charge per one point of FIM gain also was substantially higher. Although subacute rehabilitation was found to be more cost-effective than acute, additional research is needed to establish policies regarding rehabilitation services.

Activities of Daily Living↗
PubMed1995

Conformational modeling of substrate binding to endocellulase E2 from Thermomonospora fusca.

Molecular mechanics calculations have been used to place a cellotetraose substrate into the active site of the crystallographically determined structure of endocellulase E2 from Thermomonospora fusca. In the lowest energy model structure, the second residue of the substrate oligosaccharide is tilted away from the planar ribbon geometry of cellulose as it is in the X-ray structure of the E2cd-cellobiose co-crystal. This tilt is the result of the topology of the binding site, and results in several strong carbohydrate-protein hydrogen bonds. The tilting produces a twisting of the glycosidic linkage of the cleavage site between residues two and three. In the predicted enzyme-substrate complex both of the Asp residues believed to function in general acid and base roles in the previously proposed model for the mechanism are distant from the bond being cleaved. Molecular dynamics simulations of the complex were conducted, and while the putative catalytic Asp residues remained distant from the cleavage site, the proton of Tyr73 briefly came within van der Waals contact of the linkage oxygen.

Actinomycetales↗
PubMed1995

The cellular location of Prevotella ruminicola beta-1,4-D-endoglucanase and its occurrence in other strains of ruminal bacteria.

Prevotella ruminicola B(1)4, TC1-1, TF1-3, and TS1-5 all produced immunologically cross-reacting 88- and 82-kDa carboxymethyl cellulases (CMCases). P. ruminicola 23, 118B, 20-63, and 20-78 had much lower CMCase activities, and Western blots (immunoblots) showed no cross-reaction with the B(1)4 CMCase antiserum. Fibrobacter succinogenes S85 and Selenomonas ruminantium HD4 and D produced CMCase, but these enzymes were smaller and did not cross-react with the B(1)4 CMCase antiserum. The B(1)4 CMCase antiserum inhibited the B(1)4, TC1-1, TF1-3, and TS1-5 CMCase activities and agglutinated these cells, but it had no effect on the other strains or species. On the basis of these results, the B(1)4 CMCase is a strain-specific enzyme that is located on the outside surface of the cells. P. ruminicola B(1)4 cultures, grown on sucrose, did not have significant CMCase activity, but these cells could bind purified 88- and 82-kDa CMCase but not 40.5-kDa CMCase. Because the 40.5-kDa CMCase is a fully active, truncated form of the CMCase, it appears that the N-terminal domain of the 88-kDa B(1)4 CMCase anchors the CMCase to the cells. Cells grown on cellobiose produced at least 10-fold more CMCase than the sucrose-grown cells, and the cellobiose-grown cells could only bind 15% as much CMCase as sucrose-grown cells. Virtually all of the CMCase activity of exponentially growing cultures was cell associated, but CMCase activity was eventually detected in the culture supernatant. On the basis of the observation that the 88-kDa CMCase was gradually converted to the 82-kDa CMCase when cultures reached the stationary phase without a change in specific activity, it appears that the 82-kDa protein is probably a proteolytic degradation product of the 88-kDa CMCase.

Animals↗
PubMed1995

Cloning, sequencing, and characterization of a membrane-associated Prevotella ruminicola B(1)4 beta-glucosidase with cellodextrinase and cyanoglycosidase activities.

Prevotella ruminicola B(1)4 is a gram-negative, anaerobic gastrointestinal bacterium. A 2.4-kbp chromosomal fragment from P. ruminicola encoding an 87-kDa aryl-glucosidase (CdxA) with cellodextrinase activity was cloned into Escherichia coli DH5 alpha and sequenced. CdxA activity was found predominantly in the membrane fraction of both P. ruminicola and E. coli, but P. ruminicola localized the protein extracellularly while E. coli did not. The hydrolase had the highest activity on cellodextrins (3.43 to 4.13 mumol of glucose released min-1 mg of protein-1) and p-nitrophenyl-beta-D-glucoside (3.54 mumol min-1 mg of protein-1). Significant activity (70% of p-nitrophenyl-beta-D-glucoside activity) was also detected on arbutin and prunasin. Less activity was obtained with cellobiose, amygdalin, or gentiobiose. CdxA attacks cellodextrins from the nonreducing end, releasing glucose units, and appears to be an exo-1,4-beta-glucosidase (EC 3.2.1.74) which also is able to attack beta-1,6 linkages. Comparison of the deduced amino acid sequence with other glycosyl-hydrolases suggests that this enzyme belongs to family 3 (B. Henrissat, Biochem. J. 280:309-316, 1991). On the basis of this sequence alignment, the catalytic residues are believed to be Asp-275 and Glu-265. This is the first report of a cloned ruminal bacterial enzyme which can cleave cyanogenic plant compounds and which may therefore contribute to cyanide toxicity in ruminants.

Amino Acid Sequence↗
PubMed1995

Immunofluorescent analysis of the spinal cord in dysraphic mice.

Development of the spinal cord was analyzed immunocytochemically at 10-12 days of gestation in normal and dysraphic embryos of the loop-tail mutant mouse, using an anti-neural cell adhesion molecule (NCAM) and the lectin concanavalin A (Con A) as histological markers for evaluating neural cell organization and distribution. The normal and abnormal embryos showed similar patterns of reactivity to anti-NCAM and Con A, even though the neural folds were open and everted in the abnormal embryos, with displacement of the dorsal root ganglia. In the abnormal embryos the floor plate was similar to that in normal embryos, as evidenced by its increased anti-NCAM and Con A labeling relative to that in the rest of the neuroepithelium. Moreover, each lateral end of the everted abnormal neuroepithelium developed an attenuated 'roof plate' that appeared to be structurally similar to the normal roof plate. However, some of these 'roof plates' exhibited prominent clusters of labeled and nonlabeled cells, especially in the 10-day embryos. In addition, whereas normal embryos showed strong luminal labeling of the neuroepithelial cells with Con A, comparable regions in the abnormals were spotty and poorly defined except for the 'roof plate' and floor plate. The results indicate that dorsoventral polarity in the spinal cord, as assessed structurally and histochemically, develops essentially normally in abnormal dysraphic embryos, even though the topographic relationships of the abnormal neural tube are disturbed.

Animals↗
PubMed1995

Targeted mutagenesis of the transcription factor GATA-4 gene in mouse embryonic stem cells disrupts visceral endoderm differentiation in vitro.

Transcription factor GATA-4 belongs to a family of zinc finger proteins involved in lineage determination. GATA-4 is first expressed in yolk sac endoderm of the developing mouse and later in cardiac tissue, gut epithelium and gonads. To delineate the role of this transcription factor in differentiation and early development, we studied embryoid bodies derived from mouse embryonic stem (ES) cells in which both copies of the Gata-4 gene were disrupted. Light and electron microscopy demonstrated that embryoid bodies formed from wild-type and heterozygous deficient ES cells were covered with a layer of visceral yolk sac endoderm, whereas no yolk sac endoderm was evident on the surface of the homozygous deficient embryoid bodies. Independently selected homozygous deficient cell lines displayed this distinctive phenotype, suggesting that it was not an artifact of clonal variation. Biochemical markers of visceral endoderm formation, such as alpha-feto-protein, hepatocyte nuclear factor-4 and binding sites for Dolichos biflorus agglutinin, were absent from the homozygous deficient embryoid bodies. Examination of other differentiation markers in the mutant embryoid bodies, studies of ES cell-derived teratocarcinomas and chimeric mouse analysis demonstrated that GATA-4-deficient ES cells have the capacity to differentiate along other lineages. We conclude that, under in vitro conditions, disruption of the Gata-4 gene results in a specific block in visceral endoderm formation. These homozygous deficient cells should yield insights into the regulation of yolk sac endoderm development and the factors expressed by visceral endoderm that influence differentiation of adjoining ectoderm/mesoderm.

Animals↗
PubMed1995

Evaluating food fortification options: general principles revisited with folic acid.

OBJECTIVES: This article uses folic acid as an example to illustrate some of the complex issues and general principles that emerge when evaluating fortification of the food supply as one possible means to address a public health recommendation. METHODS: Distributions of current daily folate intakes from conventional foods and dietary supplements were estimated. Intakes that might result from fortification of cereal-grain products and ready-to-eat cereals at various levels for eight age-gender groups were also estimated by using the US Department of Agriculture's 1987-1988 Nationwide Food Consumption Survey. RESULTS: The results illustrate that fortification of the US food supply tends to increase folate intakes of consumers at the high end of the intake distribution curves in the general population to a greater extent than it affects consumers at the low end of the intake distribution curves in the target population. CONCLUSIONS: The effectiveness of food fortification options for a target population and the safety for the general population impose conflicting challenges that must be considered concurrently when making decisions about fortifying the US food supply.

Adolescent↗
PubMed1995

Patterns of lectin binding during mammalian neurogenesis.

Temporospatial changes in surface carbohydrates of neuroepithelial cells were analysed by means of lectin histochemistry in normal mouse embryos subsequent to closure of the neural tube. The lectins used were concanavalin A (con A), soybean (SBA), Maclura pomifera (MPA), peanut (PNA), wheatgerm (WGA), succinylated wheatgerm (sWGA) and Limax flavus (LFA). Although labelling was obtained with all of the lectins, the most striking temporospatial differences occurred with con A which in the early embryos (9-10 somites) labelled the basal and intercellular surfaces, but not the luminal surfaces of the neuroepithelial cells, whereas in the older embryos (26-30 somites), con A showed light luminal surface labelling. A midventral wedge of cells in the floor of the neural tube in the older embryos also exhibited more intense labelling with con A, WGA, and sWGA than with the other lectins. In addition, comparisons of lectin localisation were made between the closed neural tube in normal embryos and the open neural folds in the loop-tail (Lp) mutant mouse in which the neural tube fails to close. Although similar temporospatial patterns in lectin localisation occurred as in normal embryos, the retention of lectin labelling associated with rounded putative neural crest cells that remained sequestered in the apices of the open neural folds, along with an attenuation of the luminal reaction in the older abnormal embryos, suggest that during normal mammalian development closure of the spinal neural folds may be important for the timely exit of neural crest cells as well as for eliciting changes in the luminal surfaces of the neuroepithelial cells.

Animals↗
PubMed1995

Localisation of glycoproteins and glycosaminoglycans during early eye development in the macaque.

The composition of the extracellular matrix (ECM) was examined in the developing lens and optic cup (stages 11-16) of the long-tailed monkey (Macaca fascicularis) using peroxidase immunocytochemistry. The glycoproteins, fibronectin, laminin, and collagen types I and IV, were consistently associated with basement membranes (BM) of ocular epithelia at all stages examined. Discontinuity of the optic cup BM was observed during the early stages of evagination (stages 11 and 12); the even distribution of all 4 components was reestablished by stage 13 when the optic vesicle is closely apposed to the thickened lens placode. While fibronectin was most predominant in the mesenchymal matrix, all 4 glycoproteins were observed to variable degrees in the periocular mesenchyme. Particularly strong glycoprotein reactivity was observed in the interspace between the invaginating lens vesicle and optic cup whereas no significant reactivity occurred within the lens, developing retina or future corneal epithelium. Two glycosaminoglycans, hyaluronic acid and chondroitin sulphate, had virtually identical widespread staining patterns in all ocular BM and throughout the periocular mesenchyme and adjacent epithelial tissues, including the lens and retina. The observed temporal and regional staining patterns suggest that these ECM components are morphogenetic factors in the macaque eye, facilitating the complex series of integrated tissue interactions, movements and shape changes during the earliest stages of lens and optic vesicle morphogenesis. The macaque offers a valuable model to study these interactions due to the prolonged period of ocular development which is morphologically identical to humans.

Animals↗
PubMed1994

Rat T cell response to superantigens. I. V beta-restricted clonal deletion of rat T cells differentiating in rat-->mouse chimeras.

T cells of mice display V beta-specific reactivity for a spectrum of mouse mammary tumor virus (Mtv) antigens; confrontation with these antigens during ontogeny causes substantial "holes" in the T cell repertoire. Since endogenous Mtv antigens are rare in other species, the question arises whether V beta-specific recognition of Mtv antigens is unique to mice. To examine this question, rat T cells were allowed to differentiate from stem cells in severe combined immunodeficiency (SCID) mice. These rat-->mouse xenochimeras were prepared under a variety of conditions. The results show that rat T cells are strongly reactive to mouse Mtv antigens, both in terms of tolerogenicity and immunogenicity. In fact, the V beta specificity of rat and mouse T cells for Mtv antigens is almost indistinguishable.

Animals↗
PubMed1994

Rat T cell responses to superantigens. II. Allelic differences in V beta 8.2 and V beta 8.5 beta chains determine responsiveness to staphylococcal enterotoxin B and mouse mammary tumor virus-encoded products.

The previous paper in this series demonstrates that rat T cells developing de novo in the presence of mouse mammary tumor virus (Mtv) antigens in rat-->severe combined immunodeficiency (SCID) mouse xenochimeras display a distinct pattern of V beta-restricted deletion; this deletion pattern is remarkably similar to that occurring during thymic development of mouse T cells in Mtv+ strains. In addition, T cells developing in the absence of Mtv antigens in these rat-->mouse xenochimeras are tolerant of host antigens, but show strong primary proliferative responses in cultures stimulated with Mtv-7+ (Mlsa) mouse cells; like the mouse, these rat T cell responses are dominated by V beta 6 and V beta 8 T cells. Here, we continue analysis of rat T cell responses to superantigens; we show that T cells from Lewis and Fischer 344 rats expressing V beta 8.2 display an important all-or-nothing difference in their responses to Mtv-7 superantigens. This all-or-none strain difference in the response to Mtv-7 applies also to the response by V beta 8.2 and V beta 8.5 T cells to the soluble superantigen staphylococcal enterotoxin B. Because these two rat strains express different alleles of these two V beta 8 family members, this finding identifies additional, hitherto unreported residues of the T cell receptor beta chain important in T cell responses to superantigens.

Alleles↗