Publications

minimization of the escherichia coli genome using a tn5-targeted cre/loxp excision system.	an increasing number of microbial genomes have been completely sequenced, and functional analyses of these genomic sequences are under way. to facilitate these analyses, we have developed a genome-engineering tool for determining essential genes and minimizing bacterial genomes. we made two large pools of independent transposon mutants in escherichia coli using modified tn5 transposons with two different selection markers and precisely mapped the chromosomal location of 800 of these transposons. ...	2002	12244329
[expression of cre gene in escherichia coli and bioassay its expression product].	the cre recombinase from bacteriophage p1 can recognize specific dna sequences, cleave dna at specific target sites, and then ligate it to the cleaved dna of a second site. in this study, cre gene was cloned into the pgem-t easy vector via pcr procedure. then the cre gene was inserted into an expression vector pet-29a and expressed in e. coli bl21 (de3). a 38 kd soluble protein was expressed and named cre. cre was purified by deae-52 chromatography. bioassay of the partially purified product sho ...	2002	12385251
doc-mediated cell killing in shigella flexneri using a c1/laci controlled expression system.	in this report we describe the development of a highly stringent and dually regulated promoter system for shigella flexneri. dual regulation was provided by utilizing a promoter susceptible to control by the bacteriophage p1 temperature-sensitive c1 repressor that in turn was under the transcriptional control of laci. the level of induction/repression ratios observed was up to 3700-fold in s. flexneri. the general utility of this promoter system was evaluated by demonstrating that the bacterioph ...	2002	12399040
the p1 plasmid in action: time-lapse photomicroscopy reveals some unexpected aspects of plasmid partition.	the prophage of bacteriophage p1 is a low copy number plasmid in escherichia coli and is segregated to daughter cells by an active partition system. the dynamics of the partition process have now been successfully followed by time-lapse photomicroscopy. the process appears to be fundamentally different from that previously inferred from statistical analysis of fixed cells. a focus containing several plasmid copies is captured at the cell center. immediately before cell division, the copies eject ...	2002	12460532
directed evolution of the site specificity of cre recombinase.	cre recombinase from bacteriophage p1 recognizes a 34-bp recombination site, loxp, with exquisite sequence specificity and catalyzes the site-specific insertion, excision, or rearrangement of dna. to better understand the molecular basis of protein-dna recognition and generate recombinases with altered specificities, we have developed a directed evolution strategy that can be used to identify recombinases that recognize variant loxp sites. to be selected, members of a library of cre variants pro ...	2002	11904359
development of a p1 phagemid system for the delivery of dna into gram-negative bacteria.	the inability to transform many clinically important gram-negative bacteria has hampered genetic studies addressing the mechanism of bacterial pathogenesis. this report describes the development and construction of a delivery system utilizing the broad-host-range transducing bacteriophage p1. the phagemids used in this system contain a p1 pac initiation site to package the vector, a p1 lytic replicon to generate concatemeric dna, a broad-host-range origin of replication and an antibiotic-resista ...	2002	11932441
efficient recombination in diverse tissues by a tamoxifen-inducible form of cre: a tool for temporally regulated gene activation/inactivation in the mouse.	in recent years, the cre integrase from bacteriophage p1 has become an essential tool for conditional gene activation and/or inactivation in mouse. in an earlier report, we described a fusion protein between cre and a mutated form of the ligand binding domain of the estrogen receptor (cre-er) that renders cre activity tamoxifen (tm) inducible, allowing for conditional modification of gene activity in the mammalian neural tube in utero. in the current work, we have generated a transgenic mouse li ...	2002	11944939
tight regulation and modulation via a c1-regulated promoter in escherichia coli and pseudomonas aeruginosa.	we describe the development and analysis of a novel promoter system regulated by the bacteriophage p1 temperature-sensitive c1 repressor. using transcriptional fusions to the lacz reporter gene to monitor gene expression, we show that the ratio of induction/repression can be up to 1500-fold in escherichia coli. the promoters exhibited extremely tight repression and could be modulated over a range of temperatures. the utility of the promoter system was tested in pseudomonas aeruginosa. c1 effecti ...	2002	12000993
e-cadherin is a survival factor for the lactating mouse mammary gland.	the ca(++)-dependent cell adhesion molecule e-cadherin is expressed throughout mouse development and in adult tissues. classical gene targeting has demonstrated that e-cadherin-deficient embryos die at the blastocyst stage. to study the involvement of e-cadherin in organogenesis, a conditional gene inactivation scheme was undertaken using the bacteriophage p1 recombinase cre/loxp system. mice with homozygous loxp sites in both alleles of the e-cadherin (cdh1) gene were generated and these mice w ...	2002	12049767
unmodified cre recombinase crosses the membrane.	site-specific recombination in genetically modified cells can be achieved by the activity of cre recombinase from bacteriophage p1. commonly an expression vector encoding cre is introduced into cells; however, this can lead to undesired side-effects. therefore, we tested whether cell-permeable cre fusion proteins can be directly used for lox-specific recombination in a cell line tailored to shift from red to green fluorescence after loxp-specific recombination. comparison of purified recombinant ...	2002	12060697
murine peripherin gene sequences direct cre recombinase expression to peripheral neurons in transgenic mice.	spatially and temporally regulated somatic mutations can be achieved by using the cre/loxp recombination system of bacteriophage p1. to develop a cell type-specific system of gene targeting in the peripheral nervous system, we generated the transgenic mouse lines expressing cre recombinase under the control of the mouse peripherin gene promoter. the activity of the cre recombinase during embryonic development was examined by mating the peripherin-cre transgenic mice to the knock-in cre-mediated ...	2002	12123806
identification of a new human cyp2a gene fragment with close linkage to cyp2gp1.	human genomic libraries were screened to identify cyp2g-related cytochrome p450 genes. a genomic fragment comprising exons 7 through 9 of cyp2gp1 and exons 6 through 9 of a previously unidentified cyp2a gene, designated cyp2a7p2, was isolated from an embl3 library; the two genes were arranged in outward opposite directions with about 8 kbp of intervening sequence. the same structure was also detected in a bacteriophage p1 clone, which contained a full-length cyp2gp1 gene, exons 6 through 9 of cy ...	2001	11124222
application of cre-loxp system to the urinary tract and cancer gene therapy.	the bacteriophage p1-derived cre-loxp system is a powerful and versatile tool for in vivo dna recombination. it is widely used in gene targeting research. the combination of the cre-loxp system and a specific promoter enables conditional "knockout" of a target gene in a particular tissue or cell type. it has also made it possible to delete genes in adult animals that are essential for embryogenesis. this system is also used to enhance tissue- or tumor-specific promoter activities that are useful ...	2001	11690553
dna substrates influence the recombination efficiency mediated by flp recombinase expressed in mammalian cells.	the flp recombinase derived from saccharomyces cerevisiae mediates precise site-specific recombination between a pair of flp recognition targets (frts). like the cre/loxp system derived from bacteriophage p1, the flp/frt system has recently been applied to gene regulation systems using an flp-expressing recombinant adenovirus (rad) (nakano et al, nucleic acids res. 29: e40, 2001). in an attempt to improve the flp/frt system by altering its dna substrates, we compared the recombination efficiency ...	2001	11694078
controlled expression in klebsiella pneumoniae and shigella flexneri using a bacteriophage p1-derived c1-regulated promoter system.	the utility of promoters regulated by the bacteriophage p1 temperature-sensitive c1 repressor was examined in shigella flexneri and klebsiella pneumoniae. promoters carrying c1 operator sites driving lacz expression had induction/repression ratios of up to 240-fold in s. flexneri and up to 50-fold in k. pneumoniae. the promoters exhibited remarkably low basal expression, demonstrated modulation by temperature, and showed rapid induction. this system will provide a new opportunity for controlled ...	2001	11698385
strong minor groove base conservation in sequence logos implies dna distortion or base flipping during replication and transcription initiation.	the sequence logo for dna binding sites of the bacteriophage p1 replication protein repa shows unusually high sequence conservation ( approximately 2 bits) at a minor groove that faces repa. however, b-form dna can support only 1 bit of sequence conservation via contacts into the minor groove. the high conservation in repa sites therefore implies a distorted dna helix with direct or indirect contacts to the protein. here i show that a high minor groove conservation signature also appears in sequ ...	2001	11726698
the p1 phage replication protein repa contacts an otherwise inaccessible thymine n3 proton by dna distortion or base flipping.	the repa protein from bacteriophage p1 binds dna to initiate replication. repa covers one face of the dna and the binding site has a completely conserved t that directly faces repa from the minor groove at position +7. although all four bases can be distinguished through contacts in the major groove of b-form dna, contacts in the minor groove cannot easily distinguish between a and t bases. therefore the 100% conservation at this position cannot be accounted for by direct contacts approaching in ...	2001	11726699
genetic organization of the francisella plasmid pfnl10.	we report here the molecular characterization of pfnl10, a 3990-bp cryptic plasmid of francisella novicida-like f6168. the plasmid was maintained in f. novicida utah 112 and f. tularensis lvs strains. we sequenced the entire plasmid and found six open reading frames (orfs)-orf1, orf2, orf3, orf4, orf5, and orfm. orf3, orf4, orf5, and orfm are located on the same strand, and we designated it the plus strand. orf1 and orf2 are on the complementary strand. the orfs appear to be arranged in two oper ...	2001	11735370
efficient gene activation in cultured mammalian cells mediated by flp recombinase-expressing recombinant adenovirus.	a recombinant adenovirus (rad) expressing cre recombinase derived from bacteriophage p1 has already been extensively used for the conditional gene activation and inactivation strategies in mammalian systems. in this study, we generated axcaflp, a rad expressing flp recombinase derived from saccharomyces cerevisiae and carried out quantitative comparisons with cre-expressing rad in both in vitro and in cultured cells to provide another efficient gene regulation system in mammalian cells. in the i ...	2001	11266575
translocation pathway of protein substrates in clpap protease.	intracellular protein degradation, which must be tightly controlled to protect normal proteins, is carried out by atp-dependent proteases. these multicomponent enzymes have chaperone-like atpases that recognize and unfold protein substrates and deliver them to the proteinase components for digestion. in clpap, hexameric rings of the clpa atpase stack axially on either face of the clpp proteinase, which consists of two apposed heptameric rings. we have used cryoelectron microscopy to characterize ...	2001	11287666
interruption of coding sequences by heterologous introns can enhance the functional expression of recombinant genes.	sustained expression of recombinant proteins is a critical factor for the effectiveness of numerous applications in the biomedical sciences including the treatment of human disease by gene therapy, the large scale production of therapeutic proteins, as well as the investigation of gene function by transgenesis or cell type specific mutagenesis. although much attention has been paid to the optimisation of regulatory sequences such as promoters, untranslated regions and polyadenylation signals, ef ...	2001	11320412
a structural view of cre-loxp site-specific recombination.	structural models of site-specific recombinases from the lambda integrase family of enzymes have in the last four years provided an important new perspective on the three-dimensional nature of the recombination pathway. members of this family, which include the bacteriophage p1 cre recombinase, bacteriophage lambda integrase, the yeast flp recombinase, and the bacterial xercd recombinases, exchange strands between dna substrates in a stepwise process. one pair of strands is exchanged to form a h ...	2001	11340053
intein-mediated rapid purification of cre recombinase.	cre recombinase produced by bacteriophage p1 catalyzes site-specific recombination of dna between loxp recognition sites in both prokaryotic and eukaryotic cells and has been widely used for genome engineering and in vitro cloning. recombinant cre has been overproduced in escherichia coli and its purification involves multiple steps. in this report, we used an "intein" fusion system to express cre as a c-terminal fusion to a modified protein splicing element, i.e., intein. the modified intein co ...	2001	11388811
smallest region of overlapping deletion in 1p36 in human neuroblastoma: a 1 mbp cosmid and pac contig.	in human neuroblastomas, the distal portion of 1p is frequently deleted, as if one or more tumor suppressor genes from this region were involved in neuroblastoma tumorigenesis. earlier studies had identified a smallest region of overlapping deletion (sro) spanning approximately 23 cm between the most distally retained d1s80 and by the proximally retained d1s244. in pursuit of generating a refined delineation of the minimally deleted region, we have analyzed 49 neuroblastomas of different stages ...	2001	11391793
isolation and characterization of the murine transforming growth factor-beta2 promoter.	this report describes the isolation and characterization of the 5' flanking region of the murine transforming growth factor beta-2 (tgf-beta2) gene. a genomic clone containing the promoter region of the gene was isolated after screening a bacteriophage p1 genomic library. the resulting clone was sequenced and compared to promoters for the human and chicken tgf-beta2 genes. the sequence located near the transcription start site is highly conserved. it includes a tata box, an e-box, and a largely ...	2001	11404017
directional resolution of synthetic holliday structures by the cre recombinase.	the cre recombinase of bacteriophage p1 cleaves its target site, loxp, in a defined order. recombination is initiated on one pair of strands to form a holliday intermediate, which is then resolved by cleavage and exchange of the other pair of strands to yield recombinant products. to investigate the influence of the loxp sequence on the directionality of resolution, we constructed synthetic holliday (chi) structures containing either wild-type or mutant lox sites. we found that cre preferentiall ...	2001	11406627
using an in vivo phagemid system to identify non-compatible loxp sequences.	the site-specific recombination system of bacteriophage p1 is composed of the cre recombinase that recognizes a 34-bp loxp site. the cre/loxp system has been extensively used to manipulate eukaryotic genomes for functional genomic investigations. the creation of additional heterologous loxp sequences potentially expands the utility of this system, but only if these loxp sequences do not recombine with one another. we have developed a stringent in vivo assay to examine the degree of recombination ...	2001	11418130
dual regulatory control of a particle maturation function of bacteriophage p1.	a unique arrangement of promoter elements was found upstream of the bacteriophage p1 particle maturation gene (mat). a p1-specific late-promoter sequence with conserved elements located at positions -22 and -10 was expected from the function of the gene in phage morphogenesis. in addition to a late-promoter sequence, a -35 element and an operator sequence for the major repressor protein, c1, were found. the -35 and -10 elements constituted an active escherichia coli sigma(70) consensus promoter, ...	2001	11418548
definition of a 1-mb homozygous deletion at 9q32-q33 in a human bladder-cancer cell line.	we performed detailed molecular analyses of a suspected homozygous deletion on chromosome 9q32-q33 in a bladder-cancer cell line (kybtds) derived from a superficial papillary transitional cell carcinoma (tcc). we examined 13 sequence-tagged site (sts) markers mapped along 9q32-q33 by polymerase chain reaction (pcr), and used 13 bacterial artificial chromosome (bac)/bacteriophage p1-derived artificial chromosome (pac) genomic clone probes representing these sts markers as probes for dual-color fl ...	2001	11450846
altered directionality in the cre-loxp site-specific recombination pathway.	the site-specific recombinase cre must employ control mechanisms to impose directionality on recombination. when two recombination sites (locus of crossing over in phage p1, loxp) are placed as direct repeats on the same dna molecule, collision between loxp-bound cre dimers leads to excision of intervening dna. if two sites are placed as inverted repeats, the intervening segment is flipped around. cre catalyzes these reactions in the absence of protein co-factors. current models suggest that dir ...	2001	11492999
delivery of the cre recombinase by a self-deleting lentiviral vector: efficient gene targeting in vivo.	the cre recombinase (cre) from bacteriophage p1 is an important tool for genetic engineering in mammalian cells. we constructed lentiviral vectors that efficiently deliver cre in vitro and in vivo. surprisingly, we found a significant reduction in proliferation and an accumulation in the g(2)/m phase of cre-expressing cells. to minimize the toxic effect of cre, we designed a lentiviral vector that integrates into the host genome, expresses cre in the target cell, and is subsequently deleted from ...	2001	11553794
using an in vivo phagemid system to identify non-compatible loxp sequences.	the site-specific recombination system of bacteriophage p1 is composed of the cre recombinase that recognizes a 34-bp loxp site. the cre/loxp system has been extensively used to manipulate eukaryotic genomes for functional genomic investigations. the creation of additional heterologous loxp sequences potentially expands the utility of this system, but only if these loxp sequences do not recombine with one another. we have developed a stringent in vivo assay to examine the degree of recombination ...	2001	11576551
detection of illegitimate rearrangement within the immunoglobulin locus on 14q32.3 in b-cell malignancies using end-sequenced probes.	translocation involving the immunoglobulin heavy chain (igh) locus is a recurring event in b-cell oncogenesis. the aim of this study was to characterize clones from bacterial artificial chromosome (bac) libraries and/or bacteriophage p1 artificial chromosome libraries spanning the igh locus for detection of illegitimate rearrangement within the region by fluorescence in situ hybridization (fish). in silico analysis of the igh variable (ighv) dna sequence (nt_001716.v1) was performed to identify ...	2001	11579466
construction of bacteriophage p1 libraries with large inserts.	the bacteriophage p1 cloning system was originally developed as an alternative to yac and cosmid systems for cloning high-molecular-weight genomic dna. this unit details the preparation of the bacteriophage p1 library. three support protocols provide the raw materials for the basic procedure, including the vector (pad10sacbii), the mammalian dna inserts, and the two packaging extracts that contain the viral proteins necessary to construct a p1 bacteriophage incorporating the vector and insert. a ...	2001	18428291
targeted somatic mutagenesis in mouse epidermis.	gene targeting in the mouse is a powerful tool to study mammalian gene function. the possibility to efficiently introduce somatic mutations in a given gene, at a chosen time and/or in a given cell type will further improve such studies, and will facilitate the generation of animal models for human diseases. to create targeted somatic mutations in the epidermis, we established transgenic mice expressing the bacteriophage p1 cre recombinase or the tamoxifen-dependent cre-er(t2) recombinase under t ...	2000	11595821
the amino terminus of bacteriophage lambda integrase is involved in protein-protein interactions during recombination.	bacteriophage lambda integrase (int) catalyzes at least four site-specific recombination pathways between pairs of attachment (att) sites. protein-protein contacts between monomers of int are presumed to be important for these site-specific recombination events for several reasons: int binds to the att sites cooperatively, catalytic int mutants can complement each other for strand cleavage, and crystal structures for two other recombinases in the int family (cre from phage p1 and int from haemop ...	2000	10648529
mammalian genomes contain active recombinase recognition sites.	recombinases derived from microorganisms mediate efficient site-specific recombination. for example, the cre recombinase from bacteriophage p1 efficiently carries out recombination at its loxp target sites. while this enzyme can function in mammalian cells, the 34bp loxp site is expected to be absent from mammalian genomes. we have discovered that sequences from the human and mouse genomes surprisingly divergent from loxp can support cre-mediated recombination at up to 100% of the efficiency of ...	2000	10689186
molecular organization of the mouse gastrin-releasing peptide receptor gene and its promoter.	the murine gastrin-releasing peptide receptor (mgrp-r) is a member of the g protein-coupled receptor family and mediates important physiological actions of its specific ligand, the gastrointestinal hormone/neurotransmitter grp, including mitogenic properties in the mouse swiss 3t3 fibroblasts. glucocorticoids and increases in intracellular camp are reported to alter grp-r gene transcription, but the molecular basis for these effects is unknown. to begin to identify possible gene regulatory mecha ...	2000	10689196
cre-mediated cerebellum- and hippocampus-restricted gene mutation in mouse brain.	using the phage p1-derived cre/loxp recombination system, we have created a line of cre-transgenic mice in which the cre-mediated gene deletion is restricted to granule cells of cerebellum and dentate gyrus of hippocampus. low levels of deletion were also present in pyramidal cells of hippocampal ca1 and ca3 fields. the cre/loxp recombination occurred prenatally. the recombination efficiencies in the granular layer of the cerebellum, the granular layer of the dentate gyrus, and the ca1 and ca3 p ...	2000	10694492
genomic organization and chromosomal mapping of elks, a gene rearranged in a papillary thyroid carcinoma.	we recently isolated a novel cdna, designated elks, that was fused to ret cdna in a papillary thyroid carcinoma. its encoded polypeptide sequence was rich in glutamic acid (e), leucine (l), lysine (k), and serine (s), and was characterized by the presence of nine alpha-helical coiled-coil domains consisting of periodic heptad repeats. we have now cloned the entire structure of the human elks gene from within a 700-kb genomic region represented by overlapping bacteriophage p1-derived artificial c ...	2000	10697956
synthesis of a new cre recombinase gene based on optimal codon usage for mammalian systems.	the origin of the cre recombinase gene is bacteriophage p1, and thus the codon usages are different from in mammals. in order to adapt this codon usage for mammals, we synthesized a "mammalian cre recombinase gene" and examined its expression in chinese hamster ovarian tumor (cho) cells. significant increases in protein production as well as mrna levels were observed. when the recombination efficiency was compared using cho cell transfectants having a cdna containing loxp sites, the "mammalian c ...	2000	10731707
a family of removable cassettes designed to obtain antibiotic-resistance-free genomic modifications of escherichia coli and other bacteria.	modifications of microbial genomes often require the use of the antibiotic-resistance (anb(r))-encoding genes and other easily selectable markers. we have developed a set of such selectable markers (cm(r), km(r) and gm(r)), which could easily be inserted into the genome and subsequently removed by using the cre/loxp site-specific recombination system of bacteriophage p1. in this manner the same marker could be used more than once in the same background, while the resulting strain could or would ...	2000	10773465
a sequence-ready physical map of the region containing the human natural killer gene complex on chromosome 12p12.3-p13.2.	we developed a sequence-ready physical map of a part of human chromosome 12p12.3-p13.2 where the natural killer gene complex (nkc) is located. the nkc includes a cluster of genes with structure similar to that of the ca(2+)-dependent lectin superfamily of glycoproteins that are expressed on the surface of most natural killer (nk) cells and a subset of t cells. these killer cell lectin-like receptors (klr) are involved in nk target cell recognition, leading to activation or inhibition of nk cell ...	2000	10783260
inter-chromosomal recombination of mll and af9 genes mediated by cre-loxp in mouse development.	chromosomal translocations are crucial events in the aetiology of many leukaemias, lymphomas and sarcomas, resulting in enforced oncogene expression or the creation of novel fusion genes. the study of the biological outcome of such events ideally requires recapitulation of the tissue specificity and timing of the chromosomal translocation itself. we have used the cre-loxp system of phage p1 to induce de novo mll-af9 chromosomal recombination during mouse development. loxp sites were introduced i ...	2000	11265751
in vivo and in vitro function of groel mutants with impaired allosteric properties.	escherichia coli cells that produce only plasmid-encoded wild-type or mutant groel were generated by bacteriophage p1 transduction. effects of mutations that affect the allosteric properties of groel were characterized in vivo. cells containing only groel(r197a), which has reduced intra-ring positive cooperativity and inter-ring negative cooperativity in atp binding, grow poorly upon a temperature shift from 25 to 42 degrees c. this strain supports the growth of phages t4 and t5 but not phage la ...	2000	10973985
illegitimate cre-dependent chromosome rearrangements in transgenic mouse spermatids.	the bacteriophage p1 cre/loxp system has become a powerful tool for in vivo manipulation of the genomes of transgenic mice. although in vitro studies have shown that cre can catalyze recombination between cryptic "pseudo-loxp" sites in mammalian genomes, to date there have been no reports of loxp-site infidelity in transgenic animals. we produced lines of transgenic mice that use the mouse protamine 1 (prm1) gene promoter to express cre recombinase in postmeiotic spermatids. all male founders an ...	2000	11087830
the assembly of large bacs by in vivo recombination.	we have developed a method for recombining bacterial artificial chromosomes (bacs) and p1 artificial chromosomes (pacs) containing large genomic dna fragments into a single vector using the cre-lox recombination system from bacteriophage p1 in vivo. this overcomes the limitations of in vitro methods for generating large constructs based on restriction digestion, ligation, and transformation of dna into escherichia coli cells. we used the method to construct a human artificial chromosome vector o ...	2000	11112344
stability and dna binding of the phd protein of the phage p1 plasmid addiction system.	the plasmid addiction module of bacteriophage p1 encodes two proteins, doc, a toxin that is stable to proteolytic degradation, and phd, the toxin's antidote that is proteolytically unstable. phd has been shown to autoregulate its expression by specific dna binding. here, we investigate the secondary structure and thermal stability of phd, the effect of operator dna binding on the structure and stability of phd, and the stoichiometry, affinity, and cooperativity of phd binding to operator subsite ...	1999	9915794
the applications of fish in tumor pathology.	the current fish technology was greatly improved during the past 10 years. a large number of cosmids and yeast (yacs), bacterial (bacs), phage p1 derived (pacs) artificial chromosomes have been rapidly mapped and are useful as probes. in parallel, methods were established to specifically "paint" entire chromosomes or chromosome segments. using these chromosome libraries as probes, complex rearrangements and marker chromosomes can be identified irrespective of their banding pattern. ripetitive dn ...	1999	10936888
genetic analysis of the mouse x inactivation center defines an 80-kb multifunction domain.	dosage compensation in mammals occurs by x inactivation, a silencing mechanism regulated in cis by the x inactivation center (xic). in response to developmental cues, the xic orchestrates events of x inactivation, including chromosome counting and choice, initiation, spread, and establishment of silencing. it remains unclear what elements make up the xic. we previously showed that the xic is contained within a 450-kb sequence that includes xist, an rna-encoding gene required for x inactivation. ...	1999	10097124
the doc toxin and phd antidote proteins of the bacteriophage p1 plasmid addiction system form a heterotrimeric complex.	the toxin (doc) and antidote (phd) proteins of the plasmid addiction system of bacteriophage p1 were purified as a complex. cocrystals of the complex contained a 2:1 molar ratio of phd:doc as assayed by dye binding following sds-polyacrylamide gel electrophoresis and as determined by amino acid analysis. gel filtration and analytical ultracentrifugation revealed that the two addiction proteins interact in solution to form a p2d trimer composed of one doc and two phd molecules. these results supp ...	1999	10358024
the topological mechanism of phage lambda integrase.	bacteriophage lambda integrase (int) is a versatile site-specific recombinase. in concert with other proteins, it mediates phage integration into and excision out of the bacterial chromosome. int recombines intramolecular sites in inverse or direct orientation or sites on separate dna molecules. this wide spectrum of int-mediated reactions has, however, hindered our understanding of the topology of int recombination. by systematically analyzing the topology of int reaction products and using a m ...	1999	10369759
topological selectivity of a hybrid site-specific recombination system with elements from tn3 res/resolvase and bacteriophage p1 loxp/cre.	in order to investigate the functions of the parts of the tn 3 recombination site res, we created hybrid recombination sites by placing the loxp site for cre recombinase adjacent to the "accessory" resolvase-binding sites ii and iii of res. the efficiency and product topology of in vitro recombination by cre between two of these hybrid sites were affected by the addition of tn 3 resolvase. the effects of resolvase addition were dependent on the relative orientation and spacing of the elements of ...	1999	10373363
a sequence-ready 840-kb pac contig spanning the candidate tumor suppressor locus dbc1 on human chromosome 9q32-q33.	a putative tumor suppressor locus involved in bladder cancer has been mapped to human chromosome 9q32-q33 and designated dbc1. our previous microsatellite-based deletion mapping study indicated that dbc1 was localized between d9s1848 and afma239xa9. we have constructed an 840-kb sequence-ready contig composed of bacteriophage p1-derived artificial chromosomes (pacs), which encompasses dbc1. clones were initially identified by screening a pac library with markers localized to the region by physic ...	1999	10444335
gene targeting restricted to mouse striated muscle lineage.	spatially and temporally regulated somatic mutations can be achieved by using the cre/loxp recombination system of bacteriophage p1. in order to develop gene knockouts restricted to striated muscle, we generated a transgenic mouse line expressing cre recombinase under the control of the human alpha-skeletal actin promoter. specific excision of a loxp-flanked gene was demonstrated in striated muscle, heart and skeletal muscle, in a pattern very similar to the expression of the endogenous alpha-sk ...	1999	10481039
identification and characterization of the single-stranded dna-binding protein of bacteriophage p1.	the genome of bacteriophage p1 harbors a gene coding for a 162-amino-acid protein which shows 66% amino acid sequence identity to the escherichia coli single-stranded dna-binding protein (ssb). the expression of the p1 gene is tightly regulated by p1 immunity proteins. it is completely repressed during lysogenic growth and only weakly expressed during lytic growth, as assayed by an ssb-p1/lacz fusion construct. when cloned on an intermediate-copy-number plasmid, the p1 gene is able to suppress t ...	1999	10515938
the bacteriophage p1 humd protein is a functional homolog of the prokaryotic umud'-like proteins and facilitates sos mutagenesis in escherichia coli.	the escherichia coli umud and umuc genes comprise an operon and encode proteins that are involved in the mutagenic bypass of normally replication-inhibiting dna lesions. umud is, however, unable to function in this process until it undergoes a reca-mediated cleavage reaction to generate umud'. many homologs of umudc have now been identified. most are located on bacterial chromosomes or on broad-host-range r plasmids. one such putative homolog, humd (homolog of umud) is, however, found on the bac ...	1999	10559166
a non-cytotoxic herpes simplex virus vector which expresses cre recombinase directs efficient site specific recombination.	the coding sequences for the bacteriophage p1 recombinase cre were cloned into the genome of a herpes simplex virus type 1 (hsv-1) mutant which is severely impaired for the synthesis of immediate early (ie) proteins. the resulting recombinant, virus in1372, expressed functional cre which mediated the excision in trans of loxp-flanked sequences located in the hsv-1 genome, both in tissue culture cells and in vivo in mouse sensory neurons. infection with in1372 also resulted in recombination, at h ...	1999	10564749
a recombinase-based selection of differentially expressed bacterial genes.	bacterial genes are often differentially expressed in response to specific environmental conditions. we have devised a method to identify regulated bacterial promoters, such that transient promoter expression leads to a permanent and selectable change in bacterial phenotype. this system consists of a promoterless derivative of cre, the phage p1 recombinase, carried on a plasmid, and two chromosomal loxp sites, the targets of the cre recombinase. the loxp sites flank npt, conferring kanamycin res ...	1999	10564816
nuclear targeting determinants of the phage p1 cre dna recombinase.	the cre dna recombinase of bacteriophage p1 has become a useful tool for genomic manipulation in mice and other eukaryotes. because cre is of prokaryotic origin, the 38 kda protein has been presumed to gain access to the eukaryotic nucleus simply because it is sufficiently small to pass through the nuclear pore by passive diffusion. instead, we show here that cre carries nuclear targeting determinants that efficiently direct cre entry into the nucleus of mammalian cells. fusions of cre with gree ...	1999	10572169
the anti-immunity system of phage-plasmid n15: identification of the antirepressor gene and its control by a small processed rna.	n15 is a temperate virus of escherichia coli related to lambdoid phages. however, unlike all other known phages, the n15 prophage is maintained as a low copy number linear dna molecule with covalently closed ends. the primary immunity system at the immb locus is structurally and functionally comparable to that of lambdoid phages, and encodes the immunity repressor cb. we have characterized a second locus, imma, in which clear plaque mutations were mapped, and found that it encodes an anti-immuni ...	1999	10594823
a 2-mb sequence-ready contig map and a novel immunoglobulin superfamily gene igsf4 in the loh region of chromosome 11q23.2.	human chromosome 11q23.2 has been proposed to contain a tumor suppressor gene(s) whose deletion has been associated with cancer of the lung and breast and with neuroblastoma. to analyze the genomic structure and to isolate a candidate tumor suppressor gene from this region, we constructed a 2-mb sequence-ready contig map using bacteriophage p1 (p1), bacterial artificial chromosome (bac), and p1-derived artificial chromosome (pac). the map comprises a contig of 24 overlapping p1, bac, and pac clo ...	1999	10610705
conditional gene targeting in macrophages and granulocytes using lysmcre mice.	conditional mutagenesis in mice has recently been made possible through the combination of gene targeting techniques and site-directed mutagenesis, using the bacteriophage p1-derived cre/loxp recombination system. the versatility of this approach depends on the availability of mouse mutants in which the recombinase cre is expressed in the appropriate cell lineages or tissues. here we report the generation of mice that express cre in myeloid cells due to targeted insertion of the cre cdna into th ...	1999	10621974
structure and chromosomal localization of the mouse bombesin receptor subtype 3 gene.	bombesin (bn)-like peptides/neurotransmitters mediate a broad range of physiological funtions in the gastrointestinal tract and the central nervous system through binding to their specific, high-affinity mammalian bombesin receptors. this family of heptahelical, g-protein coupled receptors includes the gastrin-releasing peptide receptor (grp-r, or bb2), neuromedin b receptor (nmb-r, or bb1), and the bombesin receptor subtype 3 (brs-3, or bb3). the tissue distribution of brs-3 is quite dissimilar ...	1998	9573346
inducible gene targeting in mice using the cre/lox system.	molecular techniques now allow the design of precise genetic modifications in the mouse. not only can defined nucleotide changes be engineered into the genome of the mouse, but genetic switches can be designed to target expression or ablation of any gene (for which basic molecular information is available) to any tissue at any defined time. these strategies promise to contribute substantially to an increased understanding of individual gene function in development and pathogenesis. a powerful to ...	1998	9608509
transfer of p1 inserts into a yeast-bacteria shuttle vector by co-transformation mediated homologous recombination.	manipulation of genomic inserts cloned into the bacteriophage p1 vector is hindered by the large size of the inserts. we have used co-transformation mediated recombination between the yeast-bacteria shuttle vector, pclasper, and various p1 clones to transfer the entire insert from the p1 into pclasper. this results in the insert being stably maintained in yeast, facilitating mutagenesis by homologous recombination. the recombinant plasmid can subsequently be transferred to and stably maintained ...	1998	9671827
site-specific recombination using an epitope tagged bacteriophage p1 cre recombinase.	since the original description of cre mediated site-specific recombination in bacteriophage p1 (sternberg, n., hamilton, d., 1981 j. mol. biol., 150, 467-487), the cre-lox system of recombination has been widely used to manipulate prokaryotic and eukaryotic genomes. unfortunately, there are few means available to measure cre protein expression in vivo. we have constructed an expression vector wherein the cre protein is tagged at the carboxy terminus with an 11-amino-acid epitope to the herpes si ...	1998	9714840
cre mutants with altered dna binding properties.	the recombinase cre of bacteriophage p1 is a member of the family of site-specific recombinases and integrases that catalyze inter- and intramolecular dna rearrangements. to understand how this protein specifically recognizes its target sequence, we constructed cre mutants with amino acid substitutions in different positions of the presumptive dna binding region. here we present the results of in vitro dna binding and in vivo recombination experiments with these cre mutants. most substitutions o ...	1998	9722507
insulin-like growth factor-i affects perinatal lethality and postnatal development in a gene dosage-dependent manner: manipulation using the cre/loxp system in transgenic mice.	insulin-like growth factor-i (igf-i) is essential for cell growth, differentiation and postnatal development. a null mutation in igf-1 causes intrauterine growth retardation and perinatal lethality. the present study was designed to test the lower limit of igf-1 gene dosage that ensures survival and postnatal growth by using the cre/loxp system. mice with variable reductions in igf-i levels were generated by crossing eiia-cre transgenic mice and mice with loxp-flanked igf-1 locus (igf-1/flox). e ...	1998	9731712
cre-loxp-mediated inactivation of the alpha6a integrin splice variant in vivo: evidence for a specific functional role of alpha6a in lymphocyte migration but not in heart development.	two splice variants of the alpha6 integrin subunit, alpha6a and alpha6b, with different cytoplasmic domains, have previously been described. while alpha6b is expressed throughout the development of the mouse, the expression of alpha6a begins at 8.5 days post coitum and is initially restricted to the myocardium. later in ontogeny, alpha6a is found in various epithelia and in certain cells of the immune system. in this study, we have investigated the function of alpha6a in vivo by generating knock ...	1998	9763436
comparative mapping of distal murine chromosome 11 and human 17q21.3 in a region containing a modifying locus for murine plasma von willebrand factor level.	type 1 von willebrand disease (vwd) is a common inherited disorder characterized by mild to moderate bleeding and reduced levels of von willebrand factor (vwf). an animal model for human type 1 vwd, the riiis/j mouse strain, exhibits a prolonged bleeding time and reduced plasma vwf levels. we have previously mapped the defect in riiis/j to distal mouse chr 11, distinct from the vwf locus on chr 6. this locus, mvwf, was localized to an approximately 0.5-cm interval, tightly linked to gip, distal ...	1998	9806826
comparative kinetic analysis of flp and cre recombinases: mathematical models for dna binding and recombination.	the integrase class site specific recombinases flp from saccharomyces cerevisiae, and cre from bacteriophage p1, have been extensively used to direct dna rearrangements in heterologous organisms. although their reaction mechanisms have been relatively well characterised, little comparative analysis of the two enzymes has been published. we present a comparative kinetic analysis of flp and cre, which identifies important differences. gel mobility shift assays show that cre has a higher affinity f ...	1998	9813124
accessory genes in the dara operon of bacteriophage p1 affect antirestriction function, generalized transduction, head morphogenesis, and host cell lysis.	bacteriophage p1 mutants with the 8.86-kb region between the invertible c-segment and the residential is1 element deleted from their genome are still able to grow vegetatively and to lysogenize stably, but they show several phenotypic changes. these include the formation of minute plaques due to delayed cell lysis, the abundant production of small-headed particles, a lack of specific internal head proteins, sensitivity to type i host restriction systems, and altered properties to mediate general ...	1998	9813202
complete dna sequence and detailed analysis of the yersinia pestis kim5 plasmid encoding murine toxin and capsular antigen.	yersinia pestis, the causative agent of plague, harbors at least three plasmids necessary for full virulence of the organism, two of which are species specific. one of the y. pestis-specific plasmids, pmt1, is thought to promote deep tissue invasion, resulting in more acute onset of symptoms and death. we determined the entire nucleotide sequence of y. pestis kim5 pmt1 and identified potential open reading frames (orfs) encoded by the 100,990-bp molecule. based on codon usage for known yersinial ...	1998	9826348
the potential of integrons and connected programmed rearrangements for mediating horizontal gene transfer.	site-specific recombination of integrons, mediates transfer of single genes in small genomes and plasmids. recent data suggest that new genes are recruited to the cassettes--the units moved by integrons. integrons are resident in a class of transposons with pronounced target selectivity for resolution loci in broad host range plasmids. a resulting network of programmed transfer routes, with potential offshoots reaching into eukaryotic cells, may channel genes to unexpectedly remote organisms. it ...	1998	9850680
cre/loxp-mediated in vivo excision of large segments from yeast genome and their amplification based on the 2microm plasmid-derived system.	in vivo excision and amplification of pre-determined, large genomic segments, directly from the genome of a natural host, provides an alternative to conventional cloning in foreign vectors. using this approach, we have devised an in vivo procedure for excising large segments of saccharomyces cerevisiae genome using cre/loxp system of bacteriophage p1, followed by amplification of excised circles, as based on the yeast 2microm plasmid-derived ori and flp/frt machinery. to provide the excision and ...	1998	9858689
efficient blg-cre mediated gene deletion in the mammary gland.	using the phage p1-derived cre/loxp recombination system, we have developed a strategy for efficient mammary tissue specific inactivation of floxed genes. transgenic mice were generated which express cre dna-recombinase under the control of the mammary gland specific promoter of the ovine beta-lactoglobulin (blg) gene. to test the specificity of cre mediated recombination, we crossed these mice to animals harbouring a floxed dna ligase i allele. we show that the blg-cre construct specifies mamma ...	1998	9859227
establishment of framework p1 clones for map-based cloning and genome sequencing: direct rflp mapping of large clones.	large insert capacity, clone stability and convenient propagation in escherichia coli have made bacterial artificial chromosome and phage p1 vector-based libraries the first choice for large-scale sequencing projects, and these libraries have also proven useful for chromosome walking. the application of these libraries for either purpose is greatly facilitated by the establishment of a set of framework clones distributed across the genome. using a p1-based library of arabidopsis thaliana with ge ...	1998	9931419
a 3-mb sequence-ready contig map encompassing the multiple disease gene cluster on chromosome 11q13.1-q13.3.	despite the presence of several human disease genes on chromosome 11q13, few of them have been molecularly cloned. here, we report the construction of a contig map encompassing 11q13.1-q13.3 using bacteriophage p1 (p1), bacterial artificial chromosome (bac), and p1-derived artificial chromosome (pac). the contig map comprises 32 p1 clones, 27 bac clones, 6 pac clones, and 1 yac clone and spans a 3-mb region from d11s480 to d11s913. the map encompasses all the candidate loci of bardet-biedle synd ...	1997	9405936
construction of a 780-kb pac, bac, and cosmid contig encompassing the minimal critical deletion involved in b cell chronic lymphocytic leukemia at 13q14.3.	a putative tumor suppressor gene involved in b cell chronic lymphocytic leukemia (b-cll) was mapped to human chromosome 13q14.3 close to the genetic markers d13s25 and d13s319. we constructed a 780-kb-long contig composed of cosmids, bacterial artificial chromosomes, and bacteriophage p1-derived artificial chromosomes that provides essential information and tools for the positional cloning of this gene. the conting contains both flanking markers as well as several additional genetic markers, thr ...	1997	9417905
genomic targeting of a bicistronic dna fragment by cre-mediated site-specific recombination.	the cre-recombinase of bacteriophage p1 catalyses site-specific recombination between dna fragments containing loxp sites. targeting of predefined genomic loci can be achieved by cre-mediated linkage of a promoterless resistance marker gene to a floxed promoter pre-existing in the genome. in order to avoid the introduction of plasmid sequences into the host genome, we have constructed a series of plasmids in which the dna segment to be integrated is flanked by two loxp sites. we show here that t ...	1997	9426252
cloning and characterization of the ori region of psw1200 of erwinia stewartii: similarity with plasmid p1.	the ori region of an erwinia stewartii plasmid, psw1200 (106 kb), has been cloned and sequenced. this region consists of a gene encoding a protein which has 91% similarity and 73% identity with the repa protein of bacteriophage p1. the ori region also consists of eight copies of 19-bp iterons which are highly homologous to the iterons of p1. similar to plasmid p1, psw1200 replicon has a copy number of approximately 1. on the other hand, the copy number increases about ninefold if three of the it ...	1997	9435016
replication of plasmids derived from p1, f, r1, r6k and rk2 replicons in amino acid-starved escherichia coli stringent and relaxed strains.	replication of mini-plasmids derived from bacteriophage p1 and naturally existing plasmids f, r1, r6k and rk2 in otherwise isogenic rela+ and rela- escherichia coli strains during amino acid starvation and limitation was investigated. since it was previously demonstrated that inhibition of dna synthesis or amplification of plasmid dna may depend on the nature of deprived amino acid, we starved bacteria for five different amino acids. we found differential replication of all these plasmids but rk ...	1997	9440285
efficiency of recombination by cre transient expression in embryonic stem cells: comparison of various promoters.	the cre-loxp recombination system of bacteriophage p1 is frequently utilized in genetic manipulation in embryonic stem (es) cells. the level of cre expression is critical to induce loxp site-specific recombination in es cells. to compare the efficiency of recombination, we constructed four cre expression vectors driven by different promoters: cytomegarovirus/chicken beta-actin (cag) promoter, human polypeptide chain elongation factor 1alpha (hef-1alpha) promoter, mouse phosphoglycerate kinase-1 ...	1997	9443813
alu-polymerase chain reaction genomic fingerprinting technique identifies multiple genetic loci associated with pancreatic tumourigenesis.	dna fingerprinting can be used to detect genetic rearrangements in cancer that may be associated with activation of oncogenes and inactivation of tumour suppressor genes. we have developed a fingerprinting strategy based on polymerase chain reaction (pcr) amplification of genomic dna with primers specific for the alu repeat sequences, which are highly abundant in the human genome. this has been applied to dna from pancreatic cancer and paired normal samples to isolate and identify fragments of g ...	1997	8993978
efficient removal of loxp-flanked dna sequences in a gene-targeted locus by transient expression of cre recombinase in fertilized eggs.	the bacteriophage p1 cre/loxp site-specific recombination system is a useful tool for engineering chromosomal changes in animal cells. transient expression of the cre recombinase gene directly introduced into fertilized eggs by pronuclear injection has been reported to provide an efficient method of transgene modulation in fertilized eggs. in the present study, we examined the efficacy of this method to remove loxp-flanked dna sequences in a gene-targeted locus in fertilized eggs. we replaced a ...	1997	9021742
virulence gene deletion frequency is increased in shigella flexneri following conjugation, transduction, and transformation.	some commonly used methods for introducing dna provoke spontaneous loss of expression of a virulence gene located on the high molecular mass plasmid in shigella flexneri. the introduction of plasmid dna by calcium chloride-mediated transformation in strains harbouring wild-type or mutated copies of regulatory genes resulted in the loss of expression of an mxic-lacz reporter gene at high frequency, approaching 100% in some cases. lac- segregants arose whether or not the introduced plasmids harbou ...	1997	9037774
the cre recombinase cleaves the lox site in trans.	the cre protein is a conservative site-specific recombinase that is encoded by bacteriophage p1. its function in vivo is to resolve dimeric lysogenic p1 plasmids that arise by general recombination. in this way cre facilitates effective partition of the p1 prophage. cre is a member of the integrase family of conservative site-specific recombinases. cleavage of the dna by the integrases involves covalent attachment of a conserved nucleophilic tyrosine to the 3'-phosphoryl end at the site of the b ...	1997	9038180
[modification of gene targeting method for functional analysis of the target gene in vivo].	gene targeting in es cells is a powerful tool to generate mice bearing predesigned mutations in the germ line. however, these mice carrying such constitutional mutations are often lethal and, therefore, we cannot study other functional aspects of the gene at later stages or in particular tissues. to inactivate the target gene in particular tissues or at particular stages of development, conditional gene inactivation based on the cre-loxp recombination system of bacteriophage p1 is considered one ...	1997	9063484
mechanism of protein remodeling by clpa chaperone.	clpa, a newly discovered atp-dependent molecular chaperone, remodels bacteriophage p1 repa dimers into monomers, thereby activating the latent specific dna binding activity of repa. we investigated the mechanism of the chaperone activity of clpa by dissociating the reaction into several steps and determining the role of nucleotide in each step. in the presence of atp or a nonhydrolyzable atp analog, the initial step is the self-assembly of clpa and its association with inactive repa dimers. clpa ...	1997	9144162
the type ic hsd loci of the enterobacteria are flanked by dna with high homology to the phage p1 genome: implications for the evolution and spread of dna restriction systems.	ecor124l, ecodxxl and ecoprrl are the known members of the type ic family of dna restriction and modification systems. the first three are carried on large, conjugative plasmids, while ecoprrl is chromosomally encoded. the enzymes are coded by three genes, hsdr, hsdm and hsds. analysis of the dna sequences upstream and downstream of the type ic hsd loci shows that all are highly homologous to each other and also to sequences present in the bacteriophage p1 genome. the upstream sequences include ...	1997	9157244
characterization of the lysogeny dna module from the temperate streptococcus thermophilus bacteriophage phi sfi21.	phage phi sfi21, the only temperate streptococcus thermophilus phage from our phage collection, showed extensive dna homology with virulent phages from lytic group i. southern blot hybridizations demonstrated that the phi sfi21-specific dna was clustered in an approximately 6.6-kb-long region, the putative lysogeny module. sequence analysis and database research identified an integrase within this module; orf 203 with homology to an anonymous orf 258 from the temperate lactococcal phage bk5-t; o ...	1997	9201223
the site-specific recombinase encoded by pind in shigella dysenteriae is due to the presence of a defective mu prophage.	the dna inversion systems are made up of an invertible dna segment and a site-specific recombinase gene. five systems are known in prokaryotes: the salmonella typhimurium h segment and hin gene (h-hin), phage mu g-gin, phage p1 c-cin, escherichia coli e14 p-pin, and shigella sonnei b-pinb systems. in this report a site-specific recombinase (pind) gene of shigella dysenteriae was cloned and sequenced. pind mediated inversion of five known segments at the same extent in e. coli. although one inv s ...	1997	9202481
characterization of the genomic structure and promoter of the mouse nad+-dependent 15-hydroxyprostaglandin dehydrogenase gene.	the mouse nad+-dependent 15-hydroxyprostaglandin dehydrogenase (15-pgdh) gene and its 5'-flanking region was cloned from a 129 mouse es bacteriophage p1 genomic library. the gene contains 7 exons and 6 introns and is 11.3 kb in length. the transcription initiation site was mapped at 35 bases upstream from the atg start codon. the nucleotide sequence of the 1.6 kb promoter region contains two tata boxes and a number of potential regulatory elements including sp1, cre, gre, ap1, ap2, nf-il6 and es ...	1997	9207200
a framework physical map of drosophila virilis based on p1 clones: applications in genome evolution.	the analysis of patterns of genome evolution may help to evaluate the evolutionary forces that shape the composition and organization of the genome. comparisons between the physical maps of divergent species can be used to identify conserved blocks of closely linked genes whose synteny is possibly under selective constraint. we have used in situ hybridization to determine the genomic position of 732 randomly selected clones from a bacteriophage p1 library of drosophila virilis. the resulting map ...	1997	9215559
brief expression of a gfp cre fusion gene in embryonic stem cells allows rapid retrieval of site-specific genomic deletions.	the cre dna recombinase of bacteriophage p1 has become a useful tool for precise genomic manipulation in embryonic stem (es) cells that have been gene modified by homologous recombination. we have re-engineered the cre gene to allow ready identification of living cre+cells by constructing a functional fusion between cre and an enhanced green fluorescent protein from aequorea victoria (gfps65t). the gfp cre fusion gene product rapidly targeted the nucleus in the absence of any exogenous nuclear l ...	1997	9241248
exclusion of bmp6 as a candidate gene for cleidocranial dysplasia.	cleidocranial dysplasia (ccd) is an autosomal dominant, generalized skeletal dysplasia in humans that has been mapped to the short arm of chromosome 6. we report linkage of a ccd mutation to 6p21 in a large family and exclude the bone morphogenetic protein 6 gene (bmp6) as a candidate for the disease by cytogenetic localization and genetic recombination. ccd was linked with a maximal two-point lod score of 7.22 with marker d6s452 at theta = 0. one relative with a recombination between d6s451 and ...	1997	9268099
a transgenic mouse line that retains cre recombinase activity in mature oocytes irrespective of the cre transgene transmission.	the cre/loxp site-specific recombination system derived from bacteriophage p1 provides a convenient tool for directed modifications of genomes in various organisms. to exploit cre-mediated manipulation of mouse genomic sequences at the zygote stage, we have developed a transgenic mouse line carrying the cag-cre transgene in which the cre gene is under control of the cytomegalovirus immediate early enhancer-chicken beta-actin hybrid (cag) promoter. the activity of the cre recombinase at early sta ...	1997	9268708
mutation of the htrb gene in a virulent salmonella typhimurium strain by intergeneric transduction: strain construction and phenotypic characterization.	the htrb gene product of haemophilus influenzae contributes to the toxicity of the lipooligosaccharide. the htrb gene encodes a 2-keto-3-deoxyoctulosonic acid-dependent acyltransferase which is responsible for myristic acid substitutions at the hydroxy moiety of lipid a beta-hydroxymyristic acid. mass spectroscopic analysis has demonstrated that lipid a from an h. influenzae htrb mutant is predominantly tetraacyl and similar in structure to lipid iv(a), which has been shown to be nontoxic in ani ...	1997	9287009
the modified nucleoside 2-methylthio-n6-isopentenyladenosine in trna of shigella flexneri is required for expression of virulence genes.	the virulence of the human pathogen shigella flexneri is dependent on both chromosome- and large-virulence-plasmid-encoded genes. a kanamycin resistance cassette mutation in the miaa gene (miaa::km sma), which encodes the trna n6-isopentyladenosine (i6a37) synthetase and is involved in the first step of the synthesis of the modified nucleoside 2-methylthio-n6-isopentenyladenosine (ms2i6a), was transferred to the chromosome of s. flexneri 2a by phage p1 transduction. in the wild-type bacterium, m ...	1997	9294434