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A continuous high-resolution physical map spanning 17 megabases of the q12, q13.1, and q13.2 cytogenetic bands of human chromosome 19.

We report the construction of a high-resolution physical map of a 17-Mb region that encompasses the entire q12, q13.1, and q13.2 bands of human chromosome 19. The continuous map extends from a region approximately 400 kb centromeric of the D19S7 marker to the excision repair cross-complementing rodent repair deficiency complementation group 1 (ERCC1) locus. The ordered clone map has been obtained starting from a foundation of cosmid contigs assembled by automated fingerprinting and localized to the cytogenetic map by fluorescence in situ hybridization (FISH). Clonal continuity of the map has been achieved by binning and linking the premapped cosmid contigs by means of yeast artificial chromosomes (YACs). The map consists of a single contig composed of 169 YAC members (minimal spanning path of 18 YACs) linking 165 cosmid contigs. Eighty percent, or about 13.2 Mb of the entire region spanned by the map, has been resolved to the EcoRI restriction map level. Twenty-nine sequence-tagged sites associated with genetic markers or derived from FISH-mapped cosmids have been placed on the map. In addition to the ERCC1 gene area, the map includes the location of the creatine kinase muscle locus (CKM), imidazoledipetidase (PEPD), glucophosphate isomerase (GPI), myelin-associated glycoprotein (MAG), the apolipoprotein E and C (APOE and APOC) genes, and the ryanodine receptor (RYR1) gene. This type of map provides a source of continuously overlapping DNA segments at a level of resolution two orders of magnitude higher than that obtained using YACs alone. In addition, it provides ready-to-use reagents for detailed analyses at the gene level, FISH studies of chromosomal aberrations, and DNA sequencing.

Chromosome Mapping↗

Fiber FISH as a DNA Mapping Tool

Fluorescence in situ hybridization (FISH) applied to metaphase chromosomes provides a mapping resolution of 1 to 3 Mb. FISH applied to interphase nuclei has a resolution of 50 kb and ranges 1-2 Mb. This better resolution is attributed to the higher degree of chromatin decondensation. Here, we describe FISH applied to naked DNA fibers (fiber FISH) and show that with such fully decondensed chromatin a resolution range of at least 1-400 kb can be obtained. Furthermore, we show that DNA fiber FISH provides a mapping tool that is highly supplementary to restriction mapping, because it permits very accurate gap and overlap sizing. Also, DNA fiber FISH provides the means to generate "color bar codes" for disease regions, which can be used to inspect patient DNAs for suspected gene rearrangements.

Journal Article↗

The organization of macronuclear rDNA molecules of four hypotrichous ciliated protozoans.

We have compared the structure of macronuclear DNA molecules that contain rRNA genes of four hypotricous ciliates, Stylonychia pustulata, Euplotes aediculatus, Oxytricha fallax and Oxytricha nova. The macronuclear rDNA, like all macronuclear DNA in hypotrichs, exists as achromosomal molecules of approximately single-gene size. The rDNA molecules have been cloned intact as recombinant plasmids and analyzed by restriction mapping and Southern hybridization. The sites of restriction enzymes BamHI, EcoRI, HindIII, PstI, PvuII and XhoI have similar but not identical patterns in Stylonychia and the two Oxytricha rDNAs. The restriction pattern of Euplotes rDNA is unlike those of the other three, with only one site of seventeen in the same position. Despite this divergence in nucleotide sequence, the overall structure of the rDNA molecules in the four hypotrichs is constant. The size of all the rDNA molecules is the same, 7.49 kb. Also, the positions of the regions coding for 19S and 25S rRNA are alike. The 25S coding region is at the 5' end of the DNA template strand (3' end of the RNA transcript), within 500 base pairs of the terminus of the DNA molecule. The 19S coding region is adjacent to the 25S region with less than 500 base pairs of spacer lying between the two genes. The largest non-coding sequence is at the 3' end of the DNA molecule adjoining the 19S RNA gene. The 3' non-coding regions show greater sequence divergence among the different rDNAs than do the coding regions. The similarity in size and organization of these molecules and the variability in the restriction patterns suggest that the gene structure is under tighter evolutionary constraint than is the primary nucleotide sequence.

Animals↗

Establishment of HTLV-I-infected cell lines from French, Guianese and West Indian patients and isolation of a proviral clone producing viral particles.

Human T-cell leukemia virus (HTLV-I) induces adult T cell leukemia/lymphoma (ATL) and a chronic neurological disease named either tropical spastic paraparesis (TSP) or HTLV-I associated myelopathy (HAM). We report here the establishment and characterization of eight HTLV-I-infected lymphoid cell lines derived either from patients with TSP (5) or from asymptomatic carriers (1). Southern blot analysis of T cell beta chain gene rearrangements indicates that all cell lines are composed of clonal populations. The same type of analysis performed with HTLV-I-specific probes showed that they harbor 1 to 5 copies of full length proviruses often associated with deleted proviruses with a restriction map for BamHI, HindIII, PstI and SacI restriction enzymes resembling those of HTLV-I previously isolated from Japan and Caribbean area. One of the cell lines, 2060, derived from a TSP patient was shown to express a relative large amount of virus easily transmissible to fresh peripheral and cord blood lymphocytes. The full length proviral genome contained in this cell line was cloned and used in transient expression experiments. We showed that the cloned provirus was able to direct the synthesis of the major structural viral proteins, the protease and the tax and rex regulatory proteins. The structural viral proteins could be assembled into free particles detected in the culture medium of transfected cells. Although the infectivity of these viral particles remains to be determined, this new clone can be employed to examine the cell types in which this TSP-derived provirus directs viral protein synthesis and eventually replicates. It should also prove of value in studies on the early cellular events induced by viral products.

Animals↗

Plasmid involvement in the formation of a spontaneous bacteriophage insensitive mutant of Lactococcus lactis.

Lactococcus lactis subsp. lactis biovar. diacetylactis DPC721 is a spontaneous bacteriophage insensitive mutant of strain DPC220, isolated after challenge with an industrial bacteriophage, phi D1. Plasmid analysis demonstrated that the bacteriophage insensitivity was associated with the absence of two native DPC220 plasmids (pAH82 and pAH33), and the presence of a novel plasmid (pAH90) in DPC721. The plasmids were transferred by conjugative mobilization to a plasmid free background where it was confirmed by restriction mapping that pAH90 is a co-integrate formed by the precise recombination of pAH82 and pAH33. The resistance phenotype encoded by pAH90 was also active against two bacteriophage homologous for the plasmid-free strain. Plasmid pAH90 was shown to encode at least two independent resistance mechanisms, including an adsorption-inhibition mechanism and a restriction and modification system. The adsorption-inhibition mechanism encoded by the co-integrate plasmid was specific for one of the phage used in this study.

Bacteriophages↗

Detailed mapping around the breakpoint of (3;8) translocation in familial renal cell carcinoma and FRA3B.

As a critical step toward cloning the breakpoint of the (3;8) translocation observed in familial renal cell carcinoma and a common fragile site on chromosome 3p (FRA3B), we have characterized the 3p14 region containing the breakpoint and FRA3B by fluorescence in situ hybridization (FISH), pulsed-field gel electrophoresis (PFGE), and genetic linkage analysis. Of 23 cosmids mapped by FISH, 14 cosmids were distal to the breakpoint of t(3;8) and 9 were proximal. Analyses of FRA3B by FISH were identical to those for the (3;8) breakpoint and indicated that the breakpoint of t(3;8) occurred at or very close to the fragile site. We have also constructed a genetic linkage map and a preliminary long-range restriction map using PFGE of the 3p14 region. The linkage results were consistent with the physical data. The combined results of FISH, PFGE, and linkage analysis establish a basis for further experiments to clone the (3;8) breakpoint and FRA3B.

Animals↗

Unusually high recombination rate detected in the sex locus region of the honey bee (Apis mellifera).

Sex determination in Hymenoptera is controlled by haplo-diploidy in which unfertilized eggs develop into fertile haploid males. A single sex determination locus with several complementary alleles was proposed for Hymenoptera [so-called complementary sex determination (CSD)]. Heterozygotes at the sex determination locus are normal, fertile females, whereas diploid zygotes that are homozygous develop into sterile males. This results in a strong heterozygote advantage, and the sex locus exhibits extreme polymorphism maintained by overdominant selection. We characterized the sex-determining region by genetic linkage and physical mapping analyses. Detailed linkage and physical mapping studies showed that the recombination rate is <44 kb/cM in the sex-determining region. Comparing genetic map distance along the linkage group III in three crosses revealed a large marker gap in the sex-determining region, suggesting that the recombination rate is high. We suggest that a "hotspot" for recombination has resulted here because of selection for combining favorable genotypes, and perhaps as a result of selection against deleterious mutations. The mapping data, based on long-range restriction mapping, suggest that the Q DNA-marker is within 20,000 bp of the sex locus, which should accelerate molecular analyses.

Animals↗

[Construction of physical map and polymorphism analysis of mtDNA region R from Mo17CMS-J of maize].

Total DNA from twenty-six CMS lines of maize under Mo17, 77 and W23 nuclear background were used for PCR amplification, including N, T, C, S four groups of cytoplasms. The primers was prefabricated according the sequence of R region published by Zebala (1997). Through these amplifications, mitochondrial DNA fragments were obtained from maize total DNA. Generally the results in one group are identical. And they are different from the others. The amplified fragments were sequenced and also give us much more information about the structure of mitochondrial genes that may lead to CMS. In order to isolate and identify the CMS genes, we developed a new platform to construct physical map of chromosome DNA by means of restriction enzyme double-digestion. The elongation of contigs is based on Southern hybridization. Having retrieved DNA from agarose gel after electrophoresis by beta-agarase, we labelled it with 32P-dCTP as a probe. We detected the positive clones in the gene library. Two contigs were revealed. And a restriction map covering 40 kb was constructed, including R region.

Base Sequence↗

Microsatellite instability in IVS3 of murine c-fes gene: tumor-associated rearrangement and mammalian divergence.

The murine lymphomacrophage hybrids ESb, EbF1, EbF2-c4, which express c-fes constitutively, were found by Southern analysis to bear a c-fes deletion of almost 100 bp. The deleted allele was transmitted to the metastatic hybrids by their nonexpressing, poorly metastatic T-lymphoma progenitor Eb, which also has a structurally normal c-fes allele. PCR amplification and sequencing of fes cDNA spanning exons 3-5, where the deletion mapped, ruled out any involvement of coding sequences in the rearrangement. PCR amplification of the as yet unsequenced murine c-fes IVS3 and IVS4 showed they are about 50% longer than their human and feline homologs. Sequencing of IVS4 showed no difference between tumor and control DNA. Sequencing of part of the approximately 2600-bp IVS3 was guided by the restriction analysis of PCR products from control and hybrid DNAs. This showed that differences from the control appeared to be mainly located in the 900-bp HindIII-EcoRI fragment, localized in the middle of IVS3. As all three hybrids had the same restriction map, this fragment was sequenced in one of them (ESb). A run of >200 CA repeats was found in control DNA, and a reduction in the CAn microsatellite accounted for most of the c-fes deletion in the ESb hybrid. Interestingly, the 50% reduction in the size of human and feline c-fes IVS3 as compared with the murine homolog is mostly due to contraction of the same microsatellite.

Animals↗

Characterization of a temperate Streptococcus thermophilus bacteriophage and its genetic relationship with lytic phages.

The temperate Streptococcus thermophilus bacteriophage phi SFi21 showed an 38-kb-long double-stranded DNA genome with cohesive ends. A single integration site was used in lysogens established in three different S. thermophilus strains. The attP and attB sites were localized on the restriction map of phage DNA and by hybridization on pulsed field separated bacterial DNA. All laboratory-established lysogens showed in addition to integrated prophage DNA unintegrated monomer phage DNA with unligated cos sites. The genetic relatedness of phi SFi21 DNA with DNA from lytic phages was studied in dot blot and Southern blot hybridization by using individual restriction fragments of phiSFi21 DNA as probes. Lytic group I phages hybridized with fragments of the central and the right part of the phiSFi21 genome but failed to hybridize with a fragment joining both parts. Lytic group II phages showed hybridization with the right half of the phiSFi21 genome. In lytic group IV phages, biologically a heterogeneous group, many different combinations of cross hybridization were detected in accordance with the hypothesis of the modular evolution of phage genomes.

Attachment Sites, Microbiological↗

Organization of ribosomal RNA genes in the fungus Cochliobolus heterostrophus.

The genes encoding the 17S, 5.8S and 25S ribosomal RNAs in the Ascomycete Cochliobolus heterostrophus were cloned and analyzed. They are arranged in tandemly repeated units (rDNA) either 9.0 or 9.15 kilobases in length, depending upon the strain. The 5S rRNA genes are not part of the tandemly repeated rDNA. Instead, many and perhaps all of the 5S genes are dispersed in the genome, as they are in the fungi Neurospora, Aspergillus and Schizosaccharomyces. Comparative restriction maps of the rDNA from C. heterostrophus and other filamentous fungi and yeasts are presented. A survey of rDNAs from twenty-three field isolates of C. heterostrophus collected worldwide demonstrated that each isolate has one or the other of two rDNA forms, which differ in length and in the presence or absence of at least three restriction enzyme sites. The differences are all located in spacer DNA outside the coding regions for the rRNA genes. Heterogeneity in the rDNA repeat was not observed within any single isolate. The copy number of the rRNA gene cluster in C. heterostrophus is approximately 130 per haploid genome.

Ascomycota↗

[Temperate SM phage from Pseudomonas aeruginosa as a vector for cloning genetic information].

The recombinant bacteriophages with the genomes containing the DNA fragments of bacteria Erwinia chrysanthemi, including the pectatelyase gene, were constructed on the base of Pseudomonas aeruginosa temperate bacteriophage SM. The gene transferred into Pseudomonas aeruginosa PAO1 cells by transfection is expressed in the new bacterial host. The restriction maps of the recombinant bacteriophages are constructed and the position of an insert is defined. Bacteriophage SM was found to be capable of reproducing in Pseudomonas aeruginosa PAO1 cells when its DNA was shortened to 88% or increased to 111% of the normal genome length. Except for bacteriophage SM, the recombinant bacteriophage SM-2 with an unique restriction endonuclease site for XbaI can also be used as a vector for cloning. Bacteriophage SM capacity in cloning of heterological DNA at HindIII sites is not less than 8 Md, capacity of bacteriophage SM-2 is not less than 5 and 8 Md at XbaI and HindIII sites respectively.

Bacteriophages↗

Gene organization of the human high affinity receptor for IgG, Fc gamma RI (CD64). Characterization and evidence for a second gene.

We have isolated, characterized, and sequenced the gene coding for the 72-kDa human high affinity IgG FcR, hFc gamma RI. It consists of six exons and spans 9.4 kilobase pairs. The leader sequence is encoded by two exons, the second of which is 21 base pairs long and contains the predicted site of peptidase cleavage. The third, fourth, and fifth exons each encode homologous Ig-like extracellular domains. The hydrophobic transmembrane region and a highly charged cytoplasmic tail are encoded by a single final exon. The sequence of the 5'-flanking region was determined. Two major transcription initiation sites were identified by RNase protection. The first, more downstream site was confirmed by primer extension studies; canonical CAAT and TATA boxes are located in appropriate positions upstream from this site. The second transcription initiation site was utilized only in RNA from cells incubated with gamma-interferon. This site initiates transcription upstream from the first major site. These data are consistent with the finding of two species of mRNA for hFc gamma RI in myeloid cells that are upregulated when cultured with gamma-interferon. Southern analysis of genomic DNA confirms the restriction map generated from the cloned DNA. One additional HindIII fragment was observed in genomic DNA from 13 randomly selected individuals that was not present in the phage clone used to characterize the gene. This observation suggests the existence of a second hFc gamma RI gene which lacks one of the two internal HindIII sites rather than a restriction fragment length polymorphism.

Amino Acid Sequence↗

Transverse alternating field electrophoresis (TAFE).

The rapid development of electrophoretic technology during the past five years has given us a stream of improvements in the area of pulsed-field separation techniques. This progression has culminated in the conception of TAFE, a simple, high resolution technique providing straight lane geometry and separation of fragments up to 9 million base pairs in length. Pulsed-field techniques will unquestionably play a major role in the forthcoming analysis of the human genome by facilitating restriction mapping and cloning of large fragments. We have no doubt that TAFE will allow scientists to do this type of genetic analysis, faster and better than ever before.

Blotting, Southern↗

A physical map of the region encompassing the human interleukin-1 alpha, interleukin-1 beta, and interleukin-1 receptor antagonist genes.

We have constructed a restriction map of the human genomic region containing the genes encoding the three members of the interleukin-1 (IL-1) family, IL-1 alpha, IL-1 beta, and IL-1 receptor antagonist (IL-1 ra). For this purpose, pulsed-field gel electrophoresis blots were hybridized with probes derived from the three genes. The genes (IL1A, IL1B, and IL1RN, respectively) were found to map to a common restriction fragment of approximately 430 kb that is flanked by two clusters of sites for methylation-sensitive rare-cutter restriction enzymes (putative CpG islands). A likely third internal CpG island was marked by two rare-cutter sites. CpG and non-CpG-specific enzymes were used to map the three genes. Relative to one terminal CpG island, the three genes were mapped to the following intervals: IL1A was between +0 and +35 kb, IL1B was between +70 and +110 kb, and IL1RN was between +330 and +430 kb.

Chromosome Mapping↗

The human immunoglobulin kappa locus on yeast artificial chromosomes (YACs).

The human immunoglobulin kappa locus is a duplicated structure. Contigs of 600 kb with 40 Vkappa genes and 440 kb with 36 Vkappa genes had been established for the Ckappa proximal (p) and distal (d) copies, respectively. In addition the human genome contains more than 24 dispersed Vkappa genes, called orphons. In the present study, 22 kappa-locus derived YACs were analyzed in detail, while 30 orphon-derived YACs were characterized only with respect to some parameters. The kappa-locus derived YACs allowed three gaps to be closed which previously could not be bridged by cosmid and phage lambda cloning. At the 5' side, the p contig was extended in the YACs by 50 kb and the d contig by 16 kb. At the 3'side, the d contig was extended by 11.5 kb. Beyond the 3' end of the d contig a new Vkappa gene was found, which is located, according to pulsed field gel electrophoresis (PFGE) experiments, at a distance of at least 140 kb from the last Vkappa gene of the contig. This Vkappa gene, which was termed Z0, occurred on three YACs, albeit at distances smaller than 140 kb; this was probably due to deletions in the YACs caused by abundant repetitive sequences at the borders of the locus. According to its sequence and to the restriction map of its surroundings, Z0 is an orphon gene of the so-called Z family, of which several members are known to be dispersed throughout the genome. The possibility that Z0 has been the parent of the other Z orphons is discussed.

Chromosome Mapping↗

Characterization of degP, a gene required for proteolysis in the cell envelope and essential for growth of Escherichia coli at high temperature.

The degP gene, required for proteolysis in the cell envelope of Escherichia coli, maps at approximately 3.5 min on the chromosome. Null mutations in degP result in temperature-sensitive growth. In certain genetic backgrounds, expression of abnormal periplasmic or inner membrane proteins (protein fusions or proteins with internal deletions) enhances the temperature-sensitive phenotype. Such growth defects were used as a selection for cloning the degP gene into Mud4042 and pACYC184 plasmid vectors, and a restriction map was determined. Analysis of deletion and insertion mutations on one of these plasmids showed that the degP gene is approximately 1.5 kilobases in size. The plasmid-encoded DegP protein had an apparent molecular weight of 50,000, as determined by maxicell analysis. Protein fusions between DegP and alkaline phosphatase had high alkaline phosphatase enzymatic activity, indicating that DegP is a periplasmic or membrane protein.

Alkaline Phosphatase↗

A 6-Mb YAC contig in Xp22.1-p22.2 spanning the DXS69E, XE59, GLRA2, PIGA, GRPR, CALB3, and PHKA2 genes.

We report the generation of an approximately 6-Mb contig of 70 overlapping yeast artificial chromosomes (YAC) covering the interval between DXS16 and DXS1229 in Xp22.1-p22.2. Within this region lie the genes for calbindin (CALB3), gastrin-releasing peptide receptor (GRPR), phosphatidyl-inositol glycan-class A protein (PIGA), glycine receptor alpha-2 (GLRA2), phosphorylase kinase alpha (PHKA2), XE59 (a gene escaping X chromosome inactivation), and DXS69E (71-7A). YACs were isolated initially from four libraries either by hybridization or using sequence tagged sites (STSs) for DXS16, DXS9, GLRA2, DXS207, DXS43, DXS1416, DXS1317, DXS1195, and DXS418. Additional STSs were obtained from the end fragments of the original YACs studied, thus allowing us to cover the contig with a series of 73 STSs, approximately 1 per 100 kb. YAC contig construction allowed the following locus order to be established: Xpter-DXS16-DXS69E-DXS414-XE59 - DXS9 - (GLRA2, DXS987) - (PIGA, DXS207) - DXS1053-DXS197-(GRPR,DXS43)-CALB3-DXS14 16- DXS1317 - DXS1195 - DXS418 - DXS257 - (PHKA2, DXS999)-DXS443-DXS1229-Xcen. Restriction mapping of the DXS16-DXS43 interval predicted the existence of several CpG islands, suggesting the presence of other genes in the region. This work provides a starting point for further mapping and positional cloning of several X-linked disease genes.

Base Sequence↗