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D Kipling

Publications and source records attributed to D Kipling.

At least 37 records · Page 2Linked to original sources
PubMed1996

Structural variation of the pseudoautosomal region between and within inbred mouse strains.

The pseudoautosomal region (PAR) is a segment of shared homology between the sex chromosomes. Here we report additional probes for this region of the mouse genome. Genetic and fluorescence in situ hybridization analyses indicate that one probe, PAR-4, hybridizes to the pseudoautosomal telomere and a minor locus at the telomere of chromosome 9 and that a PCR assay based on the PAR-4 sequence amplifies only the pseudoautosomal locus (DXYHgu1). The region detected by PAR-4 is structurally unstable; it shows polymorphism both between mouse strains and between animals of the same inbred strain, which implies an unusually high mutation rate. Variation occurs in the region adjacent to a (TTAGGG)n array. Two pseudoautosomal probes can also hybridize to the distal telomeres of chromosomes 9 and 13, and all three telomeres contain DXYMov15. The similarity between these telomeres may reflect ancestral telomere-telomere exchange.

Animals↗
PubMed1996

High frequency de novo alterations in the long-range genomic structure of the mouse pseudoautosomal region.

The pseudoautosomal region (PAR) is a segment of shared homology between the X and Y chromosomes. Here we report physical linkage of three mouse PAR probes: DXYHgu1, DXYMov15 and (TTAGGG)n. Steroid sulphatase (Sts) maps distal to these probes, indicating that there is an internal array of the telomere sequence (TTAGGG)n in the PAR. Pseudoautosomal PacI restriction fragments, up to 2 Mb in size, are unstable in C57BL/6 x C57BL/6 crosses. New alleles, often several hundred kilobases different in size, occur at a sex-averaged rate of approximately 30% per allele. Such frequent large-scale germline genome arrangements are without precedent in mammals.

Alleles↗
PubMed1996

Epigenetic control of mammalian centromere protein binding: does DNA methylation have a role?

Chromosome 1 of the inbred mouse strain DBA/2 has a polymorphism associated with the minor satellite DNA at its centromere. The more terminal block of satellite DNA sequences on this chromosome acts as the centromere as shown by the binding of CREST ACA serum, anti-CENP-B and anti-CENP-E polyclonal sera. Demethylation of the minor satellite DNA sequences accomplished by growing cells in the presence of the drug 5-aza-2'-deoxycytidine results in a redistribution of the CENP-B protein. This protein now binds to an enlarged area on the more terminal block and in addition it now binds to the more internal block of minor satellite DNA sequences on chromosome 1. The binding of the CENP-E protein does not appear to be affected by demethylation of the minor satellite sequences. We present a model to explain these observations. This model may also indicate the mechanism by which the CENP-B protein recognises specific sites within the arrays of minor satellite DNA on mouse chromosomes.

Animals↗
PubMed1995

Generation of a human X-derived minichromosome using telomere-associated chromosome fragmentation.

A linear mammalian artificial chromosome vector will require at least three functional elements: a centromere, two telomeres and replication origins. One route to generate such a vector is by the fragmentation of an existing chromosome. We have previously described the use of cloned telomeric DNA to generate and stably rescue truncated derivatives of a human X chromosome in a somatic cell hybrid. Further rounds of telomere-associated chromosome fragmentation have now been used to engineer a human X-derived minichromosome. This minichromosome is estimated to be < 10 Mb in size. In situ hybridization and molecular analysis reveal that the minichromosome has a linear structure, with two introduced telomere constructs flanking a 2.5 Mb alpha-satellite array. The highly truncated chromosome also retains some chromosome-specific DNA, originating from Xp11.21. There is no significant change in the mitotic stability of the minichromosome as compared with the X chromosome from which it was derived.

Animals↗
PubMed1995

YAC cloning Mus musculus telomeric DNA: physical, genetic, in situ and STS markers for the distal telomere of chromosome 10.

Three Mus musculus DBA/2 YAC libraries were constructed using a half-YAC telomere cloning vector. This functional complementation approach yields libraries which include terminal restriction fragments of the mouse genome. Screening all three libraries led to the isolation of 32 independent clones which carry linear YACs containing the mouse terminal repeat sequence, (TTAGGG)n. These YACs provide a resource to isolate regions of the mouse genome close to chromosome termini and excluded from existing conventional YAC libraries. To demonstrate their utility, a hybridization probe was isolated from Mtel-1, the first (TTAGGG)n-containing YAC isolated. This probe detects a approximately 70 kb Kpnl fragment in the mouse genome which is sensitive to pretreatment with BAL31 exonuclease. A PCR-based genetic marker generated from the sequence of this probe maps 4.4 cM from the most distal anchor locus on chromosome 10 in the EUCIB interspecific backcross. STS primers for this locus, D10Hgu1, were used to isolate YAC 110F4 from a commercially available mouse YAC library. Fluorescence in situ hybridization demonstrates that YAC 110F4 hybridizes to the distal telomere of chromosome 10. Clones in this collection of telomere YACs therefore partially overlap clones in conventional YAC libraries, and thus the previously unavailable terminal regions of the mouse genome can now be linked with the developing mouse STS YAC contig. Genetic markers such as D10Hgu1 allow the ends of the mouse genetic map to be defined, thus closing the map.

Animals↗
PubMed1995

CENP-B binds a novel centromeric sequence in the Asian mouse Mus caroli.

Minor satellite DNA, found at Mus musculus centromeres, is not present in the genome of the Asian mouse Mus caroli. This repetitive sequence family is speculated to have a role in centromere function by providing an array of binding sites for the centromere-associated protein CENP-B. The apparent absence of CENP-B binding sites in the M. caroli genome poses a major challenge to this hypothesis. Here we describe two abundant satellite DNA sequences present at M. caroli centromeres. These satellites are organized as tandem repeat arrays, over 1 Mb in size, of either 60- or 79-bp monomers. All autosomes carry both satellites and small amounts of a sequence related to the M. musculus major satellite. The Y chromosome contains small amounts of both major satellite and the 60-bp satellite, whereas the X chromosome carries only major satellite sequences. M. caroli chromosomes segregate in M. caroli x M. musculus interspecific hybrid cell lines, indicating that the two sets of chromosomes can interact with the same mitotic spindle. Using a polyclonal CENP-B antiserum, we demonstrate that M. caroli centromeres can bind murine CENP-B in such an interspecific cell line, despite the absence of canonical 17-bp CENP-B binding sites in the M. caroli genome. Sequence analysis of the 79-bp M. caroli satellite reveals a 17-bp motif that contains all nine bases previously shown to be necessary for in vitro binding of CENP-B. This M. caroli motif binds CENP-B from HeLa cell nuclear extract in vitro, as indicated by gel mobility shift analysis. We therefore suggest that this motif also causes CENP-B to associate with M. caroli centromeres in vivo. Despite the sequence differences, M. caroli presents a third, novel mammalian centromeric sequence producing an array of binding sites for CENP-B.

Animals↗
PubMed1994

Mouse centromere mapping using oligonucleotide probes that detect variants of the minor satellite.

Cytologically, the centromere is found at the very end of most Mus musculus chromosomes, co-localizing with an array of minor satellite sequences. It is separated from the euchromatin of the long arm by a large domain of heterochromatin, composed in part of arrays of major satellite sequences. We used oligonucleotide probes that specifically detect regions of sequence variation found in certain cloned minor satellite sequences. They detect a limited subset of the minor satellite arrays in the mouse genome, based on both pulsed-field gel electrophoresis and in situ hybridization data, and provide direct molecular genetic markers for individual centromeres in some inbred mouse strains. Array size polymorphisms detected by these probes map to positions consistent with the centromeres of chromosomes 1 and 14 in the BXD recombinant inbred (RI) strains. The genetic distances between these minor satellite arrays and loci on the long arms of chromosomes 1 and 14 are consistent with repression of meiotic recombination in the heterochromatic domains separating them. The existence of chromosome-specific minor satellite sequences implies that the rate of sequence exchange between non-homologous chromosomes relative to the rate between homologous chromosomes is much lower than has previously been postulated. We suggest that the high degree of sequence homogeneity of mouse satellite sequences may instead reflect recent common ancestry.

Animals↗
PubMed1993

Novel structural organisation of a Mus musculus DBA/2 chromosome shows a fixed position for the centromere.

Chromosome 1 of the inbred mouse strain DBA/2 shows an unusual polymorphism associated with its centromeric satellite DNA sequences. The minor satellite array has undergone amplification and is present as two blocks separated by major satellite sequences. Both minor satellite blocks appear to carry the sequence motif necessary for CENP-B protein binding. Despite this apparent similarity the functional centromere, as defined by the location of CREST antigens, appears to form only within the more terminal block. The two blocks also vary in that sister chromatid association only occurs with this more terminal block.

Animals↗
PubMed1992

Beginning or end? Telomere structure, genetics and biology.

The word telomere derives from the Greek word telos meaning 'end', roughly translating as 'the thing at the end' when the end is that of a chromosome. Telomeres belie their apparent simplicity of structure by being involved in a wide range of diverse biological phenomena. Much of our understanding of telomere behaviour comes from studies in lower eukaryotes such as ciliates and yeast, the subject of many recent reviews. Here we concentrate on the mammalian telomere, recent progress in its study, and how recent evidence for an involvement of telomeres in the regulation of gene expression and DNA replication in yeast points to new aspects of mammalian telomere function yet to be explored.

Animals↗
PubMed1991

rar mutations which increase artificial chromosome stability in Saccharomyces cerevisiae identify transcription and recombination proteins.

In an attempt to identify trans-acting factors involved in replication origin function, we have characterized the RAR3 and RAR5 genes, identified by mutations which increase the mitotic stability of artificial chromosomes whose replication is dependent on the activity of weak ARS elements. Sequence analysis has shown that the RAR3 gene is identical to GAL11/SPT13, which encodes a putative transcription factor involved in the expression of a wide range of genes. Change-of-function mutations that truncate the RAR3 protein appear to be required to enhance chromosome stability. In contrast, loss of the RAR5 protein results in enhanced chromosome stability, as if the protein is an inhibitor of ARS function. The RAR5 gene encodes the 175 kDa DNA strand transfer protein beta, an activity that can promote the transfer of a strand from a double-stranded DNA molecule to a complementary single strand. This observation implies that a presumed recombination activity can affect eukaryotic chromosomal replication.

Chromosomes, Fungal↗
PubMed1991

Mouse minor satellite DNA genetically maps to the centromere and is physically linked to the proximal telomere.

As an adjunct to attempts to define functionally important sequences at human centromeres, we have undertaken a long-range physical analysis of these regions in the mouse. Mouse centromeres are usually situated very close to the chromosome ends and are closely associated with minor satellite sequences on the basis of cytological observations. Using pulsed-field gel electrophoresis we find that this satellite DNA is arranged as tandem arrays, predominantly uninterrupted by nonsatellite sequences. These arrays can be released largely intact by digestion with a range of enzymes that generally cleave frequently in non-satellite DNA. The restriction fragments carrying these arrays are polymorphic in size between inbred strains and provide direct markers for mouse centromeres. To illustrate the possible use of these polymorphic markers we have mapped a 1.3-Mb PvuII variant in a set of RI strains to the centromere of Chromosome 7. The minor satellite arrays are very close to the centromeric telomere and physical linkage with terminal repeat sequences can readily be detected, placing many minor satellite arrays on terminal restriction fragments smaller than 1 Mb. The apparent lack of any sizable amount of nonsatellite DNA between the minor satellite and the terminal repeat arrays indicates that many mouse chromosomes are truly telocentric.

Alleles↗
PubMed1990

Hypervariable ultra-long telomeres in mice.

Telomere structure and behaviour is less well understood in vertebrates than it is in ciliates and yeasts (reviewed in ref. 1). Like all other eukaryotic chromosomes, those of vertebrates terminate in an array of a short repeated sequence. In vertebrates this sequence is (TTAGGG)n, as shown by in situ hybridization. In humans, these terminal repeats are heterogeneous in length, averaging about 10 kilobases in blood cells. Here we report the structure and inheritance of the terminal repeats present at mouse telomeres. The (TTAGGG)n tracts are many times larger than those present at human telomeres. Because of their constancy in length through somatic cell divisions, they are resolved as multiple discrete restriction fragments of up to 150 kilobases. Strikingly, this banding pattern is highly polymorphic within populations of inbred mice, suggesting an unusually high mutation rate. Indeed, although the banding pattern is inherited in a largely mendelian fashion, (TTAGGG)n tracts of new size appear frequently in family studies.

Animals↗
PubMed1990

Reversion of autonomously replicating sequence mutations in Saccharomyces cerevisiae: creation of a eucaryotic replication origin within procaryotic vector DNA.

To investigate how a defective replicon might acquire replication competence, we have studied the reversion of autonomously replicating sequence (ARS) mutations. By mutagenesis of a Saccharomyces cerevisiae plasmid lacking a functional origin of replication, we have obtained a series of cis-acting mutations which confer ARS activity on the plasmid. The original plasmid contained an ARS element inactivated by point mutation, but surprisingly only 1 of the 10 independent Ars+ revertants obtained shows a back mutation in this element. In the remainder of the revertants, sequence changes in the M13 vector DNA generate new ARSs. In two cases, a single nucleotide change results in an improved match to the ARS consensus, while six other cases show small duplications of vector sequence creating additional matches to the ARS consensus. These results suggest that changes in replication origin distribution may arise de novo by point mutation rather than by transposition of preexisting origin sequences.

Base Sequence↗
PubMed1989

Analysis of expression of hybrid yeast genes containing ARS elements.

In an attempt to devise a new assay for ARS-binding proteins we have inserted the HO ARS between the upstream activation site and the TATA region of the yeast CYC1 promoter. A marked reduction in promoter activity is observed. Inactivation of the HO ARS element by point mutation does not restore promoter activity to its original level, although a modest activation is seen. We have also inserted the HO ARS into the intron of the yeast actin gene; although there is no apparent deleterious effect on transcription, the activity of the ARS is abolished in this new environment.

Blotting, Northern↗