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Biomedical subjects

J Zissler

Publications and source records attributed to J Zissler.

12 recordsLinked to original sources
PubMed1990

Transposon tagging of genes for cell-cell interactions in Myxococcus xanthus.

The prokaryote Myxococcus xanthus is a model for cell interactions important in multicellular behavior. We used the transposon TnphoA to specifically identify genes for cell-surface factors involved in cell interactions. From a library of 10,700 insertions of TnphoA, we isolated 36 that produced alkaline phosphatase activity. Three TnphoA insertions tagged cell motility genes, called cgl, which control the adventurous movement of cells. The products of the tagged cgl genes could function in trans upon other cells and were localized primarily in the cell envelope and extracellular space, consistent with TnphoA tagging genes for extracellular factors controlling motility.

Alkaline Phosphatase↗
PubMed1989

Movement of multiple DNA units between Myxococcus xanthus cells.

Myxococcus xanthus YS produces particles (Mx alpha particles) that transmit genetic information between cells. Mx alpha particles might be viruses, although no host able to sustain lytic growth of Mx alpha has been discovered. The particles could be detected by their ability to transduce a Tn5 transposon tag to recipient bacteria. DNA from purified particles hybridized to a limited number of DNA restriction fragments of strain YS, suggesting that Mx alpha particles contain only specific DNA sequences. A set of Tn5 insertions residing in the transducible region provided genetic markers for cloning cellular DNA packaged by Mx alpha. A map of this region showed that transducible DNA comprised multiple units of approximately 80 kilobases each. Individual units share DNA homology but are divergent in the location of restriction sites. Other wild-type isolates of Myxococcus species contained DNA sequences with homology to Mx alpha DNA, indicating that Mx alpha DNA is widespread in nature. Experiments on the transfer of Mx alpha DNA in strain YS suggested that DNA transfer is enhanced during the developmental cycle.

Blotting, Southern↗
PubMed1985

Transposon tagging to detect a latent virus in Myxococcus xanthus.

Transposon mutagenesis of the bacterium Myxococcus xanthus with the transposon Tn5 revealed a special class of bacterial mutants that transduced the transposon through culture supernatant fluids. Virus-like particles copurified with transducing activity. Transposon tagging for detecting these virus-like particles may be generally useful in isolating endogenous viral agents capable of transferring genetic information between cells.

Bacteriophages↗
PubMed1985

Physical characterization of the genome of the Myxococcus xanthus bacteriophage MX-8.

We have constructed a restriction map for the genome of bacteriophage MX-8 from Myxococcus xanthus using the enzymes PvuII, MboI, and EcoRI. The phage genome size, as determined by restriction analysis, is 51.7 +/- 0.6 Kb. Double digestions, redigestions of isolated fragments, and crossed-contact hybridization of partial digestion products show that the restriction map is circular. Restriction analysis and Southern hybridization show that the phage DNA molecules are packaged sequentially from a concatemer starting from a specific site which we have mapped. The DNA molecules have an average terminal redundancy of approximately 8% and are circularly permuted over at least 40% of the genome.

Bacteriophages↗
PubMed1983

Genetic and physical characterization of lysogeny by bacteriophage MX8 in Myxococcus xanthus.

Myxophage MX8 can initiate a lysogenic cycle in Myxococcus xanthus. The lysogenic phage was gentically stable in vegetative cells and persisted in the latent state through many cell generations in the absence of extracellular phage reinfection. The latent state also was stable during the host developmental cycle, since myxospores transmitted latent MX8 genetic information to future progeny cells. DNA hybridization experiments to probe the structure of the lysogenic phage provided physical evidence that MX8 formed a prophage. During lysogenization, MX8 DNA was cut at a specific site (attP) on phage DNA, and we have concluded that genetic recombination between attP and a bacterial DNA site (attB) leads to integration of MX8 DNA and formation of stable MX8 prophage. The genetic and physical properties of MX8 that we describe should make MX8 useful in the analysis of development of M. xanthus by genetic methods.

Attachment Sites, Microbiological↗
PubMed1977

Insertion sequence IS2 associated with int-constitutive mutants of bacteriophage lambda.

We have examined mutations in bacteriophage lambda called int-c, which confer elevated constitutive expression on the int gene for prophage integration. One class of mutations, which map between the b538 and bio386 endpoints, does not appear to be associated with any major chromosomal modification, whereas the second class has the IS2 insertion sequence in orientation II within the region between gene int and the b538 endpoint, All int-c mutations are within gene xis, with the possible exception of int-c548, which might be located between int and xis. The present data are most consistent with the following notion: (1) the point mutations of class one inactivate the tI terminator signal of the pI-tI leader RNA for gene int and thus render int expression independent of the antiterminating action of the cII and cIII products, and (2) the second class of int-c mutants is constitutive for Int because the IS2 insertion, when strategically located between int and tI, provides a new constitutive promoter for int transciption.

Coliphages↗
PubMed1976

Insertion sequence IS2 near the gene for prophage lambda excision.

In this study we characterize a variant of the lambdacI857S7 prophage, designated lambdabi2cI857S7, which carries a DNA insertion. The insertion sequence is IS2, and it resides in the antipolar orientation II just upstream from the gene for prophage excision (xis) at 61.6%lambda. This bi2 insertion mutant could prove valuable for studies on possible recombination functions of IS2 DNA and of its effect on the lambda integration and excision functions.

Chromosome Mapping↗
PubMed1974

Role of genetic recombination in DNA replication of bacteriophage lambda. I. Genetic characterization of the delta gene.

We describe the isolation and genetic characterization of point mutations in gene delta, including a temperature-sensitive mutation (del(206)). Genetic methods enable the extraction of a delta mutation from the triple mutant (del,red,gam) and the construction of new genotypes, including del,red and del,gam double mutants. Tests of plating efficiency indicate gene delta is essential for normal phase growth on the polA host. The possible association of delta in a system involving alpha, beta, and gamma is considered.

Coliphages↗
PubMed1974

Role of genetic recombination in DNA replication of bacteriophage lambda. II. Effect in DNA replication by gene delta.

We have studied the effect of delta mutations in phage lambda on DNA synthesis as assayed by the accumulation of lambda DNA in infected cells. We find that delta mutants appear to generate somewhat less DNA than lambda(+) in a rec(+) host, suggesting the wild-type delta gene may act in DNA replication. An additional clue to delta function arises if replication is measured in the gamma-negative situation where concatemer formation is abortive. In this situation, the wild-type delta gene has an "inhibitory" effect on replication. A similar inhibitory effect on replication due to delta is observed after infection of P(2) lysogens. We conclude from these studies that the delta gene may act with alpha, beta, and gamma genes, possibly in a process affecting DNA replication.

Coliphages↗