A Physical Map of the Oryctes Baculovirus Genome

ABSTRACT Genes of the dilute-short ear (d-se) region of mouse chromosome 9 comprise an array of loci important to the normal development of the animal. Over 200 spontaneous, chemically induced and radiation-induced mutations at these loci have been identified, making it one of the most genetically well-characterized regions of the mouse. Molecular analysis of this region has recently become feasible by the identification of a dilute mutation that was induced by integration of an ecotropic murine leukemia virus genome. Several unique sequence cellular DNA probes flanking this provirus have now been identified and used to investigate the organization of wild-type chromosomes and chromosomes with radiation-induced d-se region mutations. As expected, several of these mutations are associated with deletions, and, in general, the molecular and genetic complementation maps of these mutants are concordant. Furthermore, a deletion break-point fusion fragment has been identified and has been used to orient the physical map of the d-se region with respect to the genetic complementation map. These experiments provide important initial steps for analyzing this developmentally important region at the molecular level, as well as for studying in detail how a diverse group of mutagens acts on the mammalian germline.

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Heterogeneity in Rates of Recombination Across the Mouse Genome

Genetics ◽

10.1093/genetics/142.2.537 ◽

1996 ◽

Vol 142 (2) ◽

pp. 537-548 ◽

Cited By ~ 2

Author(s):

Michael W Nachman ◽

Gary A Churchill

Keyword(s):

Linkage Map ◽

Genetic Map ◽

Large Scale ◽

Physical Map ◽

Genetic Maps ◽

Recombination Rates ◽

Physical Maps ◽

Genomic Patterns ◽

Mary Lyon ◽

Microsatellite Linkage

Abstract If loci are randomly distributed on a physical map, the density of markers on a genetic map will be inversely proportional to recombination rate. First proposed by MARY LYON, we have used this idea to estimate recombination rates from the Drosophila melanogaster linkage map. These results were compared with results of two other studies that estimated regional recombination rates in D. melanogaster using both physical and genetic maps. The three methods were largely concordant in identifying large-scale genomic patterns of recombination. The marker density method was then applied to the Mus musculus microsatellite linkage map. The distribution of microsatellites provided evidence for heterogeneity in recombination rates. Centromeric regions for several mouse chromosomes had significantly greater numbers of markers than expected, suggesting that recombination rates were lower in these regions. In contrast, most telomeric regions contained significantly fewer markers than expected. This indicates that recombination rates are elevated at the telomeres of many mouse chromosomes and is consistent with a comparison of the genetic and cytogenetic maps in these regions. The density of markers on a genetic map may provide a generally useful way to estimate regional recombination rates in species for which genetic, but not physical, maps are available.

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Assembly of the mitochondrial membrane system. Physical map of the Oxi3 locus of yeast mitochondrial DNA.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)70223-3 ◽

1980 ◽

Vol 255 (24) ◽

pp. 11922-11926 ◽

Cited By ~ 2

Author(s):

S.G. Bonitz ◽

G. Coruzzi ◽

B.E. Thalenfeld ◽

A. Tzagoloff ◽

G. Macino

Keyword(s):

Mitochondrial Dna ◽

Mitochondrial Membrane ◽

Physical Map ◽

Membrane System ◽

Yeast Mitochondrial Dna

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Multiple Chromosomes in Bacteria: The Yin and Yang of trp Gene Localization in Rhodobacter sphaeroides 2.4.1

Genetics ◽

10.1093/genetics/153.2.525 ◽

1999 ◽

Vol 153 (2) ◽

pp. 525-538

Author(s):

Chris Mackenzie ◽

Adrian E Simmons ◽

Samuel Kaplan

Keyword(s):

Rhodobacter Sphaeroides ◽

Biosynthetic Pathway ◽

Southern Blotting ◽

Physical Map ◽

Functional Integration ◽

Bacterial Genome ◽

Single Copy ◽

Gene Localization ◽

Yin And Yang ◽

Trp Genes

Abstract The existence of multiple chromosomes in bacteria has been known for some time. Yet the extent of functional solidarity between different chromosomes remains unknown. To examine this question, we have surveyed the well-described genes of the tryptophan biosynthetic pathway in the multichromosomal photosynthetic eubacterium Rhodobacter sphaeroides 2.4.1. The genome of this organism was mutagenized using Tn5, and strains that were auxotrophic for tryptophan (Trp-) were isolated. Pulsed-field gel mapping indicated that Tn5 insertions in both the large (3 Mb CI) and the small (0.9 Mb CII) chromosomes created a Trp- phenotype. Sequencing the DNA flanking the sites of the Tn5 insertions indicated that the genes trpE-yibQ-trpGDC were at a locus on CI, while genes trpF-aroR-trpB were at locus on CII. Unexpectedly, trpA was not found downstream of trpB. Instead, it was placed on the CI physical map at a locus 1.23 Mb away from trpE-yibQ-trpGDC. To relate the context of the R. sphaeroides trp genes to those of other bacteria, the DNA regions surrounding the trp genes on both chromosomes were sequenced. Of particular significance was the finding that rpsA1, which encodes ribosomal protein S1, and cmkA, which encodes cytidylate monophosphate kinase, were on CII. These genes are considered essential for translation and chromosome replication, respectively. Southern blotting suggested that the trp genes and rpsA1 exist in single copy within the genome. To date, this topological organization of the trp “operon” is unique within a bacterial genome. When taken with the finding that CII encodes essential housekeeping functions, the overall impression is one of close regulatory and functional integration between these chromosomes.

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