Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The trapping of genes in murine embryonic stem (ES) cells offers three features in one experimental approach: 1) analysis of the expression patterns of unknown genes by using a simple staining method, 2) rapid cloning of unknown genes, and 3) generation of mutant mouse lines. We performed a gene trap screen aimed at the discovery of new genes regulating embryonic development. We have processed 209 gene trap events for expression patterns in chimeric murine embryos. Randomly tested, beta-galactosidase-positive ES cell clones resulted in vivo in 35% gene trap events showing no beta-galactosidase activity, 39% gene trap events with ubiquitous beta-galactosidase activity, and 26% gene trap events showing beta-galactosidase activity restricted to specific cell types or organs. In vitro preselection reduced gene trap events with ubiquitous beta-galactosidase activity to 10% and increased the gene trap events with restricted beta-galactosidase activity to 64%, making the screening procedure for genes expressed in a restricted manner 2.5-fold more efficient. In five of the seven gene trap insertions into genes in which the expression pattern during embryogenesis was known, the beta-galactosidase marker gene reproduced faithfully the expression pattern of the trapped gene. 5'-Rapid amplification of cDNA ends (5'-RACE) of 28 gene trap events revealed 19 novel mouse genes, 8 known mouse genes, and 1 random transsplicing event. Twelve of the 25 mouse lines that crossed to homozygosity showed overt abnormalities. The genomic structure was investigated in four of these gene trap events, which caused obvious abnormalities. In all four cases, the splice-acceptor gene trap construct was inserted into an exon. One of the 13 gene trap events that did not result in overt abnormalities was examined for the presence of wild-type mRNA. Homozygous animals were found to produce normal levels of wild-type mRNA. Evidently, gene trapping does not always provide all three of the features mentioned above. In this paper, we discuss the efficiency of gene trapping and ways in which some problems may be overcome.
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PMID:Efficiency assessment of the gene trap approach. 962 93

A gene trap screen designed to isolate novel mouse genes involved in nervous system development was performed. Here, we describe the isolation and characterization of a novel gene, bodenin, which is expressed in restricted areas of the brain. beta-Galactosidase marker gene activity was detected in the embryo at the start of organogenesis (embryonic day 8.5; E8.5). Staining gradually became stronger until E12.5, when embryos exhibited widespread expression. In brains of newborn and adult mice, beta-galactosidase staining was confined predominantly to forebrain structures. Transcriptional activity was also observed in kidney, liver, lung, heart, skeletal muscle, and testes. Part of the trapped gene was isolated by 5'-rapid amplification of cDNA ends (5'-RACE). Isolation and sequencing of the complete cDNA revealed an unknown gene encoding a 200 amino acid protein. Comparison with published sequences showed 94% amino acid identity to a human integrin cytoplasmic domain-associated protein. Mice homozygous for the mutation were viable and did not exhibit any obvious abnormal phenotype. However, concealed phenotypic abnormalities cannot be excluded. The lack of readily visible abnormalities may also be due to functional compensation or to the production of low levels of wild-type protein in mice homozygous for the gene trap vector insertion. Nevertheless, the restricted expression of bodenin in the brain of newborn and adult mice suggests a role for this novel gene in the developing and mature central nervous system.
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PMID:Bodenin: a novel murine gene expressed in restricted areas of the brain. 962 4

We have isolated a rabbit neuronal nitric oxide synthase (nNOS) cDNA encoding a protein of 1,435 amino acids. Using the cDNA clones as probes, the 5'-flanking region of the nNOS gene was isolated from a rabbit genomic DNA library. 5'RACE and primer extension analysis of rabbit brain total RNA mapped multiple transcription initiation sites localized 474-487 bp upstream from the translation start codon. Analysis of 5,197 bp of the 5'-flanking sequence revealed that the rabbit nNOS gene promoter lacks canonical TATA or CCAAT boxes and, instead, contains a GC-rich region and multiple Sp1 sites. Farther from the +1start, various putative cis-elements including AP-1, AP-4, NF-kappaB, STAT, CREB, C/EBP and c-Myc were observed. The functional promoter activity of the 5'-flanking region was demonstrated by its ability to drive the expression of a beta-galactosidase reporter gene in several cell types. Serial deletion analysis of the promoter region revealed that the -291 to -172 region, which contains two Sp1 sites, is essential for basal transcriptional activity. These results suggest that the rabbit nNOS promoter contains characteristics of inducible genes.
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PMID:5'-Flanking sequence and promoter activity of the rabbit neuronal nitric oxide synthase (nNOS) gene. 1110 Nov 49

The rat LAT-1 (L-amino acid transporter-1) gene is a CD98 light chain highly expressed in cancer and development. As an initial study of the molecular basis underlying regulation of its expression, we cloned 2 kb of the LAT-1 5' flanking region. Inverse RACE and primer extension methods were used to define the transcription initiation site at 80 bp upstream from the translational start site. Functional studies carried out in normal hepatic cells using constructs containing progressive 5' deletion from region -1958 to -185 showed 3-5-fold beta-galactosidase activities over control. The presence of an activator site(s) between -52 and -185 was indicated by low activities conferred by the construct spanning this region.
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PMID:Molecular cloning of the rat TA1/LAT-1/CD98 light chain gene promoter. 1131 38

beta-galactosidases have been detected in a wide range of plants and are characterized by their ability to hydrolyse terminal non-reducing beta-D-galactosyl residues from beta-D-galactosides. These enzymes have been detected in a wide range of plant organs and tissues. In a search for differentially expressed genes during the abscission process in citrus, sequences encoding beta-galactosidase were identified. Three cDNA fragments of a beta-galactosidase gene were isolated from a cDNA subtraction library constructed from mature fruit abscission zones 48 h after the application of a mature fruit-specific abscission agent, 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole). Based on sequence information derived from these fragments, a full-length cDNA of 2847 nucleotides (GenBank accession number AY029198) encoding beta-galactosidase was isolated from mature fruit abscission zones by 5'- and 3'-RACE approaches. The beta-galactosidase cDNA encoded a protein of 737 amino acid residues with a calculated molecular weight of 82 kDa. The deduced protein was highly homologous to plant beta-galactosidases expressed in fruit ripening. Southern blot analysis demonstrated that at least two closely related beta-galactosidase genes were present in 'Valencia' orange. Temporal expression patterns in mature fruit abscission zones indicated beta-galactosidase mRNA was detected 48 h after treatment of CMN-pyrazole and ethephon in mature fruit abscission zones. beta-galactosidase transcripts were detected in leaf abscission zones only after ethephon application. The citrus beta-galactosidase was expressed in stamens and petals of fully opened flowers and young fruitlets. The results suggest that this beta-galactosidase may play a role during abscission as well as early growth and development processes in flowers and fruitlets.
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PMID:A beta-galactosidase gene is expressed during mature fruit abscission of 'Valencia' orange (Citrus sinensis). 1520 47

Cyclopropane fatty acid synthase (cfa) catalyses the transfer of a methyl group from S-adenosylmethionine (SAM) to unsaturated fatty acids. Northern blot experiments demonstrated that the Lactococcus lactis MG1363 cfa gene is mainly expressed as a bicistronic transcript together with metK, the gene encoding SAM synthetase, and is highly induced by acidity. The cfa promoter was characterized by 5'-RACE PCR, and fused to beta-galactosidase by cloning into the pAK80 plasmid. This transcriptional fusion was highly induced by acidity (23-fold at pH 5) as well as during entry into the stationary phase (8-fold) in L. lactis. Interestingly, the cfa promoter expression is repressed in a L. lactis relA* mutant which accumulates (p)ppGpp, whereas its induction by acidity appeared independent of (p)ppGpp in L. lactis and in Escherichia coli.
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PMID:Transcriptional analysis of the cyclopropane fatty acid synthase gene of Lactococcus lactis MG1363 at low pH. 1609 86

Ammonium concentration and nitrogen source regulate promoter activity and use for the transcription of chiA, the major chitinase gene of Pseudoalteromonas sp. S91 and S91CX, an S91 transposon lacZ fusion mutant. The activity of chiA was quantified by beta-galactosidase assay of S91CX cultures containing different ammonium concentrations (NH4+; 0, 9.5 or 191 mM) and with different nitrogen sources (N-acetylglucosamine (GlcNAc) or glutamate (glt)). S91 chiA expression was found to depend on both the NH4+ concentration and source of nitrogen in marine minimal medium (MMM). Pseudoalteromonas sp. S91 and S91CX can use either GlcNAc or glt as a sole source of carbon in MMM containing a standard concentration of 9.5 mM NH4+. Adding excess NH4+, 20 times the standard concentration, to MMM significantly reduced chiA activity below that found in the presence of either GlcNAc or glt. When no NH4+ was added to MMM, S91CX was also able to use either GlcNAc or glt as a source of nitrogen; under these conditions chiA activity was significantly increased. Under all conditions tested, GlcNAc induced chiA activity significantly more than glt. Regulation of bacterial chitinases by nitrogen has not been previously reported. Transcriptional start point analysis of S91 chiA, using 5'RACE (ligation-anchored PCR), showed that during growth in MMM supplemented with (1) maltose (solely a carbon source for S91), chiA transcription occurred from only one putative sigma(70)-dependent promoter; (2) the chitin monomer GlcNAc, transcription initiated from two putative sigma(54)-dependent promoters and (3) glt, transcription initiated from all three putative promoters.
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PMID:Nitrogen regulates chitinase gene expression in a marine bacterium. 1944 Feb 32

AE4 is an anion exchanger almost exclusively expressed in the collecting ducts of the kidney. This very restricted expression prompted us to analyze its transcription in more detail. 5' RACE yielded alternative transcriptional start sites that are predicted to code for N-terminal protein variants. Comparison of the 5' genomic sequence between species identified a transcriptionally active region with three conserved spans. In transgenic mice beta-galactosidase expression driven by this fragment resembled endogenous AE4 expression and was predominantly restricted to type B intercalated cells. Hence this promoter could prove useful to target type B intercalated cells by genetic approaches.
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PMID:The murine AE4 promoter predominantly drives type B intercalated cell specific transcription. 1954 66

Small regulatory RNAs (sRNAs) are versatile regulators that have been shown to be involved in the gene regulation of a growing number of biological pathways in bacteria. While finding the targets of a given sRNA has been the focus of many studies, fewer methods have been described to uncover which, if any, sRNAs regulate a given gene. Here I present two genetic screens that are designed to search for sRNAs regulating a gene of interest. Before the screens are performed, a translational fusion is made between the gene of interest and lacZ, designed so that mostly post-transcriptional effects on the gene's expression can be analyzed. I describe here a simple and rapid way to obtain this fusion, even when the transcriptional start site is unknown, by combining PCR or 5'RACE with recombination in the chromosome of a special strain of Escherichia coli. The first genetic screen uses a genomic multicopy library to find regulator genes that, when overexpressed, affect the expression of the fusion. While this technique is a classical genetic screen, particular attention is paid to how it can be used to specifically find sRNAs. A second screen is described that takes advantage of a specific library of sRNAs of E. coli that provides an easier and more rapid way to look for sRNA regulation. The library is transformed into the fusion containing strain using a serial transformation protocol developed in microtiter plates. The transformants can then be directly assayed for effects on the beta-galactosidase activity of the fusion in liquid, providing a precise and rapid way to evaluate sRNA regulation. Use of one or both of these screens should help uncover new pathways of regulation by sRNAs.
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PMID:Genetic screens to identify bacterial sRNA regulators. 2273 97