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R Kostriken

Publications and source records attributed to R Kostriken.

12 recordsLinked to original sources
PubMed2001

Engineered interphase chromosome loops guide intrachromosomal recombination.

How large-scale topologies regulate interphase chromosome function remains an important question in eukaryotic cell biology. Looped structures are thought to modulate transcription by pairing promoters with distant control elements and to orchestrate intrachromosomal recombination events by pairing appropriate recombination partners. To explore the effects of chromosomal topology on intrachromosomal recombination, distinct loop geometries were engineered into chromosome III of the budding yeast Saccharomyces cerevisiae. These topologies were created by employing pairs of lac operator clusters to serve as pairing sites and a modified lac repressor to perform the role of a protein cross-bridge. The influence of these engineered loops on the selection of donor loci during mating-type switching was evaluated using novel genetic and molecular methods. These experiments demonstrate that engineered interphase chromosome loops are biologically active-capable of influencing the course of intrachromosomal recombination. They also provide insight into the mechanism of mating-type switching by revealing a causal relationship between defined chromosomal topologies and the choice of donor locus.

Alleles↗
PubMed1995

Homologues of the engrailed gene from five molluscan classes.

We used the polymerase chain reaction (PCR) to amplify, clone, and sequence 10 engrailed homeodomains from 8 species in the five major molluscan classes, including the serially organized chiton (Polyplacophora) lineage. The Drosophila melanogaster gene engrailed (en) is one of several genes involved in embryonic segment polarity determination. Studies of engrailed sequence and expression in molluscs are of interest due to questions regarding the evolution and homology of segmentation in these taxa. Nucleotide and deduced amino acid sequence comparisons reflect evolutionary conservation within helices of the en homeodomain and ancient divergences in the region 3' to the homeodomain.

Animals↗
PubMed1992

Expression of a Wnt gene in embryonic epithelium of the leech.

A new member of the Wnt class of cell-cell communication molecules was identified in the leech Helobdella triserialis, on the basis of a conserved 86 amino acid coding sequence and exon structure. This gene, htr-wnt-A, is not an obvious homolog of any one of the previously described wnt class proteins. The embryonic expression of htr-wnt-A has been characterized at the cellular level, using nonradioactive in situ hybridization and polyclonal antibodies generated via a novel method of antigen presentation. Subcellular localization of the htr-wnt-A protein was examined by the use of immunofluorescence and confocal microscopy. htr-wnt-A is among the first zygotically expressed genes in Helobdella, appearing first in a single cell of the eight-cell embryo. In early development it is expressed within a stereotyped subset of micromeres and later, in a seemingly dynamic and stochastic pattern, by cells in a micromere-derived provisional embryonic epithelium. Its spatial and temporal expression pattern make it a candidate for participation in the regulation of cell fate in the O/P equivalence group.

Amino Acid Sequence↗
PubMed1991

Multiple modes of engrailed regulation in the progression towards cell fate determination.

The engrailed gene product of Drosophila specifies the fate of a subset of cells in each segment. Our studies of engrailed regulation suggest that fate determination is an elaborate, multistep process. At the time in embryogenesis when the engrailed-dependent cell fate is probably determined, four modes of control act in an overlapping progression to govern engrailed expression. After activation by pair-rule genes, both an extracellular signal, wingless, and autoregulation are required for engrailed expression. Autoregulation graduates to wingless independence, but is transient, and is superseded by an engrailed-independent mode of maintenance.

Animals↗
PubMed1985

Homeo box genes of the Antennapedia and bithorax complexes of Drosophila.

The Antennapedia, Ultrabithorax, and fushi tarazu genes of Drosophila melanogaster each contain a very similar protein coding sequence, the homeo box. Previously cloned homeo box sequences were used to isolate additional well conserved members of the homeo box gene family. The most strongly conserved members of the homeo box gene family map within either the Antennapedia or Bithorax gene complexes. The tissue distribution of transcripts encoded by the two rightmost homeo box genes of the Bithorax complex are compared with the iab-2 and iab-7 phenotypes.

Animals↗
PubMed1983

A site-specific endonuclease essential for mating-type switching in Saccharomyces cerevisiae.

We have detected two site-specific endonucleases in strains of Saccharomyces cerevisiae. One endonuclease, which we call YZ endo, is present only in yeast strains that are undergoing mating-type interconversion. The site at which YZ endo cleaves corresponds to the in vivo double-strand break occurring at the mating-type locus in yeast undergoing mating-type interconversion. YZ endo generates a site-specific double-strand break having 4-base 3' extensions terminating in 3' hydroxyl groups. The site of cleavage occurs in the Z1 region near the YZ junction of the mating-type locus. Mutant mating-type loci known to decrease the frequency of mating-type interconversion are correspondingly poor substrates for YZ endo in vitro. In vitro analysis of a number of such altered recognition sites has delimited the sequences required for cleavage. The molecular genetics of mating-type interconversion is discussed in the context of this endonucleolytic activity. The second endonuclease, which we refer to as Sce II, is present in all strains of S. cerevisiae we have examined. The cleavage site of Sce II has been determined and proves to be unrelated to the cleavage site of YZ endo.

Base Sequence↗
PubMed1981

Transposon Tn3 encodes a site-specific recombination system: identification of essential sequences, genes, and actual site of recombination.

The bacterial transposon Tn3 encodes a site-specific recombination system. The recombination requires the product of tnpR, a gene previously identified as a repressor of the transposase. This recombination is site specific and takes place somewhere within the sequence C-G-A-A-A-T-A-T-T-A-T-A-A-A-T-T-A-T-C but requires at least one additional sequence outside this. The phenotype of mutations in this recombination system suggests that transposition proceeds by a mechanism in which cointegrates are intermediates.

Base Sequence↗
PubMedDate not supplied

Molluscan engrailed expression, serial organization, and shell evolution.

Whether the serial features found in some molluscs are ancestral or derived is considered controversial. Here, in situ hybridization and antibody studies show iterated engrailed-gene expression in transverse rows of ectodermal cells bounding plate field development and spicule formation in the chiton, Lepidochitona cavema, as well as in cells surrounding the valves and in the early development of the shell hinge in the clam, Transennella tantilla. Ectodermal expression of engrailed is associated with skeletogenesis across a range of bilaterian phyla, suggesting a single evolutionary origin of invertebrate skeletons. The shared ancestry of bilaterian-invertebrate skeletons may help explain the sudden appearance of shelly fossils in the Cambrian. Our interpretation departs from the consideration of canonical metameres or segments as units of evolutionary analysis. In this interpretation, the shared ancestry of engrailed-gene function in the terminal/posterior addition of serially repeated elements during development explains the iterative expression of engrailed genes in a range of metazoan body plans.

Animals↗