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Biomedical subjects

V M Morales

Publications and source records attributed to V M Morales.

10 recordsLinked to original sources
PubMed1999

Regulation of human intestinal intraepithelial lymphocyte cytolytic function by biliary glycoprotein (CD66a).

Human small intestinal intraepithelial lymphocytes (iIEL) are a unique population of CD8alphabeta+ TCR-alphabeta+ but CD28- T lymphocytes that may function in intestinal epithelial cell immunosurveillance. In an attempt to define novel cell surface molecules involved in iIEL function, we raised several mAbs against activated iIELs derived from the small intestine that recognized an Ag on activated, but not resting, iIELs. Using expression cloning and binding studies with Fc fusion proteins and transfectants, the cognate Ag of these mAbs was identified as the N domain of biliary glycoprotein (CD66a), a carcinoembryonic Ag-related molecule that contains an immune receptor tyrosine-based inhibitory motif. Functionally, these mAbs inhibited the anti-CD3-directed and lymphokine-activated killer activity of the P815 cell line by iIELs derived from the human small intestine. These studies indicate that the expression of biliary glycoprotein on activated human iIELs and, potentially, other mucosal T lymphocytes is involved in the down-regulation of cytolytic function.

Animals↗
PubMed1997

General secretion pathway (eps) genes required for toxin secretion and outer membrane biogenesis in Vibrio cholerae.

The general secretion pathway (GSP) of Vibrio cholerae is required for secretion of proteins including chitinase, enterotoxin, and protease through the outer membrane. In this study, we report the cloning and sequencing of a DNA fragment from V. cholerae, containing 12 open reading frames, epsC to -N, which are similar to GSP genes of Aeromonas, Erwinia, Klebsiella, Pseudomonas, and Xanthomonas spp. In addition to the two previously described genes, epsE and epsM (M. Sandkvist, V. Morales, and M. Bagdasarian, Gene 123: 81-86, 1993; L. J. Overbye, M. Sandkvist, and M. Bagdasarian, Gene 132:101-106, 1993), it is shown here that epsC, epsF, epsG, and epsL also encode proteins essential for GSP function. Mutations in the eps genes result in aberrant outer membrane protein profiles, which indicates that the GSP, or at least some of its components, is required not only for secretion of soluble proteins but also for proper outer membrane assembly. Several of the Eps proteins have been identified by use of the T7 polymerase-promoter system in Escherichia coli. One of them, a pilin-like protein, EpsG, was analyzed also in V. cholerae and found to migrate as two bands on polyacrylamide gels, suggesting that in this organism it might be processed or otherwise modified by a prepilin peptidase. We believe that TcpJ prepilin peptidase, which processes the subunit of the toxin-coregulated pilus, TcpA, is not involved in this event. This is supported by the observations that apparent processing of EpsG occurs in a tcpJ mutant of V. cholerae and that, when coexpressed in E. coli, TcpJ cannot process EpsG although the PilD peptidase from Neisseria gonorrhoeae can.

Bacterial Outer Membrane Proteins↗
PubMed1996

IFN-gamma modulates CD1d surface expression on intestinal epithelia.

In vivo, epithelial cells that line the intestine are intimately associated with lymphocytes, termed intestinal intraepithelial lymphocytes (iIEL). A putative ligand for iIEL on intestinal epithelial cells is CD1d, and recent studies demonstrate a surface form of this molecule exists on intestinal epithelia. At present, it is not known whether CD1d expression is regulated by cytokines in the intestinal microenvironment. Thus we examined the impact of relevant cytokines on CD1d at the level of mRNA and cell surface expression. Using a sensitive whole cell enzyme-linked immunosorbent assay, we assessed the impact of relevant cytokines on CD1d expression on intestinal epithelial cell lines. We were readily able to detect CD1d on the surface of T84 cells, a cryptlike intestinal epithelial cell line. Epithelial cell exposure to human recombinant interferon-gamma (IFN-gamma) resulted in increased CD1d expression in a dose- and time-dependent manner. Polymerase chain reaction amplification of CD1d cDNA revealed a time-dependent induction after exposure to IFN-gamma. This IFN-gamma effect on CD1d expression was cytokine specific and was evident with epithelial cell lines other than T84, including Caco-2 and HT-29 cells. Finally, we were not able to detect significant surface expression of CD1a, CD1b, or CD1c on intestinal epithelial cell lines in the presence or absence of relevant cytokines. These results indicate that CD1d cell surface protein and cellular mRNA, like other major histocompatibility complex-related molecules, is cytokine regulated in intestinal epithelial cell lines.

Antigens, CD1↗
PubMed1995

Cloning of the gene encoding the mouse homologue of the human calcium signal-modulating ligand.

A cDNA clone, representing the mouse homologue of the recently described gene encoding the human calcium signal-modulating ligand, was isolated from a mouse thymus library. This clone exhibits extensive conservation of the primary nucleotide and deduced amino-acid sequences that, when considered with a similar secondary protein structure, transcript size and distribution of expression, suggests a similarity in function.

Adaptor Proteins, Signal Transducing↗
PubMed1991

A series of wide-host-range low-copy-number vectors that allow direct screening for recombinants.

A series of controlled expression vectors was constructed based on the wide-host-range plasmid pMMB66EH. Some of these new vectors code for the alpha-peptide of beta-galactosidase and allow the direct screening of recombinant clones by inactivation of alpha-complementation. The bla gene was replaced in some plasmids by the cat gene of Tn9 coding for chloramphenicol resistance, extending the use into beta-lactam-resistant strains. They all feature either the tac or taclac (tac-lac UV5 in tandem) promoters in front of a polylinker followed by the rrnB transcriptional stop point. These vectors were tested by subcloning the xylE gene coding for the Pseudomonas putida catechol 2,3-oxygenase and the Escherichia coli lamB gene coding for the lambda receptor. The expression of these genes in E. coli indicated that the tac promoter is five times stronger than the taclac promoter and that both were tightly regulated. The tac promoter in Pseudomonas syringae pv glycinea and Xanthomonas campestris pv vesicatoria had a strength similar to that in E. coli, while the taclac promoter was much weaker, reaching only 6.5 and 3% of the level of expression of the tac promoter, respectively. The taclac promoter, however, proved to be useful for the cloning in E. coli of DNA fragments that were unstable in vectors with stronger promoters and higher copy number. Expression of the lamB gene in Vibrio cholerae strain TRH7000 was not sufficient to permit cosmid transduction. Two subunits of the E. coli mannose permease, coded by the ptsP and ptsM genes, are also required for cosmid DNA penetration into the recipient cells.

Amino Acid Sequence↗
PubMed1979

Hydrolytic enzyme production by Rhizobium.

Cellulase and hemicellulase activity was detected in temperate (infective and noninfective) and tropical strains (infective) of Rhizobium. Hydrolytic enzymes were initially detected by a cup-plate assay. The presence of cellulase and hemicellulase was confirmed by viscometric assay. Implications of the presence of these enzymes in Rhizobium are discussed.

Journal Article↗
PubMed1978

Pectolytic enzymes in Rhizobium.

A sensitive pectin agar plate assay was used to demonstrate low levels of pectolytic enzymes in infective and noninfective strains of Rhizobium. The possible relation of this characteristic to legume infection is discussed.

Agar↗
PubMedDate not supplied

Comparison of the 5.8s rDNA and internal transcribed spacer sequences of isolates of Leptosphaeria maculans from different pathogenicity groups.

The regions coding for the 5.8s rRNA and the flanking internal transcribed spacers (ITS1 and ITS2) from nine isolates of the blackleg pathogen Leptosphaeria maculans and one isolate of Sclerotinia sclerotiorum were amplified by the polymerase chain reaction and sequenced. Five of the L. maculans isolates were highly virulent to Brassica plants, two were weakly virulent and two were isolated from the cruciferous weed Thlaspi arvense. The 5.8s DNA sequences of all L. maculans isolates were identical. However, there were major differences in both ITS1 and ITS2 sequences that correlated with the pathogenicity grouping. Phylogenetic analysis of the ITS sequences by both parsimony and maximum-likelihood methods indicated that each pathogenicity group was statistically different from each other with the weakly-virulent isolates being more closely related to the Thlaspi than to the highly-virulent isolates. The relationships of L. maculans to other fungi, based on a comparison of the 5.8s rDNA sequences, are discussed.

Ascomycota↗