Showing papers in "Genome in 1998"

Rapid genomic changes in newly synthesized amphiploids of Triticum and Aegilops. II. Changes in low-copy coding DNA sequences

Abstract: We recently reported that formation of allopolyploid wheat was accompanied by rapid nonrandom changes in low-copy noncoding DNA sequences. In this report we show that following allopolyploidization, changes also occurred in coding sequences. Genomic DNA of nine different newly synthesized amphiploids of different ploidy levels and their parental lines was digested with five restriction enzymes and probed with 43 coding sequences. The sequences, 19 genomic and 24 cDNA sequences, are group (homoeologous) specific and represent the proximal and distal regions of the short and long arms of the seven homoeologous groups of the Triticeae. We revealed three types of changes: disappearance of a parental hybridization fragment(s), appearance of a novel fragment(s), and simultaneous disappearance of a parental fragment(s) and appearance of a novel fragment(s). No elimination of sequences took place, since in every sequence studied the parental hybridization fragments were present in at least one of the enzyme digests. Variations in pattern among individual plants of the same amphiploid, as well as between several synthetic and natural amphiploids, indicated that at least some of the genomic changes occurred at random. Intergenomic recombination was not the cause of the observed changes. Evidence was obtained, however, that changes were also brought about by DNA methylation. Methylation may cause inactivation of genes or modify their expression levels in some of the newly synthesized amphiploid plants, leading to genetic diploidization and gene-dosage compensation and thus increasing variation among individuals.

Determination of basic chromosome numbers in the genus Saccharum by physical mapping of ribosomal RNA genes

Abstract: 18S-5.6S-25S and 5S ribosomal DNA (rDNA) sites were located by in situ hybridization to the three main species of the Saccharum genus. For each species and each rDNA family, the position and number...

Collinearity between a 30-centimorgan segment of Arabidopsis thaliana chromosome 4 and duplicated regions within the Brassica napus genome

Abstract: Arabidopsis thaliana (the model dicotyledonous plant) is closely related to Brassica crop species. Genome collinearity, or conservation of marker order, between Brassica napus (oilseed rape) and A. thaliana was assessed over a 7.5-Mbp region of the long arm of A. thaliana chromosome 4, equivalent to 30 cM. Estimates of copy number indicated that sequences present in a single copy in the haploid genome of A. thaliana (n = 5) were present in 2-8 copies in the haploid genome of B. napus (n = 19), while sequences present in multiple copies in A. thaliana were present in over 10 copies in B. napus. Genetic mapping in B. napus of DNA markers derived from a segment of A. thaliana chromosome 4 revealed duplicated homologous segments in the B. napus genome. Physical mapping in A. thaliana of homologues of Brassica clones derived from these regions confirmed the identity of six duplicated segments with substantial homology to the 7.5-Mbp region of chromosome 4 in A. thaliana. These six duplicated Brassica regions (on average 22 cM in length) are collinear, except that two of the six copies contain the same large internal inversion. These results have encouraging implications for the feasibility of shuttling between the physical map of A. thaliana and genetic maps of Brassica species, for identifying candidate genes and for map based gene cloning in Brassica crops.

Genome analysis of Thinopyrum intermedium and Thinopyrum ponticum using genomic in situ hybridization

Abstract: Genomic in situ hybridization (GISH) using genomic DNA probes from Thinopyrum elongatum (Host) D.R. Dewey (genome E, 2n = 14), Thinopyrum bessarabicum (Savul. & Rayss) A. Love (genome J, 2n = 14), and Pseudoroegneria strigosa (M. Bieb.) A. Love (genome S, 2n = 14), was used to examine the genomic constitution of Thinopyrum intermedium (Host) Barkworth & D.R. Dewey (2n = 6x = 42) and Thinopyrum ponticum (Podp.) Barkworth & D.R. Dewey (2n = 10x = 70). Evidence from GISH indicated that hexaploid Th, intermedium contained the J, Js, and S genomes, in which the J genome was related to the E genome of Th. elongatum and the J genome of Th. bessarabicum. The S genome was homologous to the S genome of Ps. strigosa, while the Js genome referred to modified J- or E-type chromosomes distinguished by the presence of S genome specific sequences close to the centromere. Decaploid Th. ponticum had only the two basic genomes J and Js. The Js genome present in Th. intermedium and Th. ponticum was homologous with E or J genomes, but was quite distinct at centromeric regions, which can strongly hybridize with the S genome DNA probe. Based on GISH results, the genomic formula of Th. intermedium was redesignated JJsS and that of Th. ponticum was redesignated JJJJsJs. The finding of a close relationship among S, J, and Js genomes provides valuable markers for molecular cytogenetic analyses using S genome DNA probes to monitor the transfer of useful traits from Th. intermedium and Th. ponticum to wheat.

The physical mapping of microsatellite markers in wheat

Abstract: Microsatellite markers represent a new class of genetic markers in plants. Such markers reveal a high level of polymorphism even in species with a narrow genetic base, such as hexaploid wheat (Triticum aestivum L.). We used a large set of such markers and 25 deletion stocks of 'Chinese Spring' in a deletion-mapping experiment to study the physical distribution of dinucleotide microsatellite markers in homoeologous group 2 chromosomes of hexaploid wheat. Thirty-one microsatellite markers identified 14 loci in chromosome 2A, 9 loci in chromosome 2B, and 10 loci in chromosome 2D. The microsatellite loci were evenly distributed along the chromosome length, marking 18 of 27 defined physical intervals, including centromeric, interstitial, and telomeric regions. The apparent random distribution indicates that microsatellite markers provide excellent coverage of the wheat genome.Key words: deletion stocks, group 2 homoeologues, microsatellites, wheat.

Application of fiber-FISH in physical mapping of Arabidopsis thaliana

Abstract: Arabidopsis thaliana has become a model plant species for genetic studies because of its small genome and short juvenility period. However, the small chromosomes of this species are not suitable for classical cytogenetic studies. Here we demonstrate that the fluorescence in situ hybridization (FISH) technique using extended DNA fibers can be a powerful tool in the physical mapping of the A. thaliana genome. Using a refined fiber-FISH technique we were able to measure DNA clusters as long as 1.71 Mb, more than 1% of the A. thaliana genome. Several small DNA loci, including the telomeres and a dispersed repetitive DNA sequence, mi167, were also analyzed with this technique. The results show that without known adjacent DNA markers such small DNA loci cannot be mapped precisely using fiber-FISH. One of the most difficult obstacles in physical mapping by contig assembly is closing the gaps that are present between adjacent contigs. Currently available molecular techniques are not sufficient to accurately estim...

Construction of a genetic linkage map and identification of AFLP markers for resistance to root-knot nematodes in peach rootstocks.

Abstract: A genetic linkage map for peach (Prunus persica (L.) Batsch) rootstocks has been constructed using amplified fragment length polymorphism (AFLP) markers in 55 F2 individuals derived from the cross ...

The distribution of male-transmitted and female-transmitted mitochondrial DNA types in somatic tissues of blue mussels : implications for the operation of doubly uniparental inheritance of mitochondrial DNA

Abstract: We have examined the mitochondrial DNA (mtDNA) content of several somatic tissues from male and female individuals of the blue mussel, Mytilus edulis. As expected from the mode of doubly uniparental inheritance (DUI) of mtDNA that is characteristic of this genus, the dominant type of mtDNA in male gonads was the male-transmitted M type. In contrast, all male somatic tissues were dominated by the female-transmitted F type. The M type could occasionally be detected in one or another tissue of a few female individuals. The findings have several implications for the operation of doubly uniparental inheritance of mitochondrial DNA, among which the most important are (i) the M genome does not have an unconditional replicative advantage over the F genome, and (ii) in contrast to "masculinization" (the process by which an F molecule assumes the role of the M genome) "feminization" (the process by which an M molecule assumes the role of the F genome) might be a rare but not impossible phenomenon.Key words: mitocho...

More than one origin of hexaploid wheat is indicated by sequence comparison of low-copy DNA

Abstract: Allohexaploid bread wheat is grown on more acreage than any other cereal crop, yet variation at the DNA level seems to be less than that observed in many diploid crop species. A common explanation ...

Development of STS markers closely linked to the vrs1 locus in barley, Hordeum vulgare

Abstract: Three random amplified polymorphic DNAs (RAPDs) closely linked to the vrs1 (formerly v) locus were sequenced and converted to sequence-tagged sites (STSs). Of the three STSs, two retained the RAPD ...

Genome size and base composition of seven Quercus species: inter- and intra-population variation

Abstract: Seven Quercus species, four deciduous (Q. cerris, Q. petraea, Q. pubescens, andQ. robur) and three evergreen (Q. coccifera, Q. ilex, andQ. suber), were assessed for DNA content. Their genome sizes ...

Identification of coupling and repulsion phase rapd markers for powdery mildew resistance gene er-1 in pea

Abstract: Powdery mildew is a serious disease of pea caused by the obligate parasite Erysiphe pisi Syd. Random amplified polymorphic DNA (RAPD) analysis has emerged as a cost-effective and efficient marker system. The objective of this study was to identify RAPD markers for powdery mildew resistance gene er-1. The resistant cultivar Highlight (carrying er-1) and the susceptible cultivar Radley were crossed, and F3 plants were screened with Operon (OP) and University of British Columbia (UBC) primers, using bulked segregant analysis. A total of 416 primers were screened, of which amplicons of three Operon primers, OPO-18, OPE-16, and OPL-6, were found to be linked to er-1. OPO-181200 was linked in coupling (trans to er-1) and no recombinants were found. OPE-161600 (4 ± 2 cM) and OPL-61900 (2 ± 2 cM) were linked in repulsion (cis to er-1). The fragments OPO-181200 and OPE-161600 were sequenced and specific primers designed. The specific primer pair Sc-OPO-181200 will be useful in identifying homozygous resistant indi...

The light gene of Drosophila melanogaster encodes a homologue of VPS41, a yeast gene involved in cellular-protein trafficking

Abstract: Mutations in a number of genes affect eye colour in Drosophila melanogaster; some of these "eye-colour" genes have been shown to be involved in various aspects of cellular transport processes. In addition, combinations of viable mutant alleles of some of these genes, such as carnation (car) combined with either light (lt) or deep-orange (dor) mutants, show lethal interactions. Recently, dor was shown to be homologous to the yeast gene PEP3 (VPS18), which is known to be involved in intracellular trafficking. We have undertaken to extend our earlier work on the lt gene, in order to examine in more detail its expression pattern and to characterize its gene product via sequencing of a cloned cDNA. The gene appears to be expressed at relatively high levels in all stages and tissues examined, and shows strong homology to VPS41, a gene involved in cellular-protein trafficking in yeast and higher eukaryotes. Further genetic experiments also point to a role for lt in transport processes: we describe lethal interactions between viable alleles of lt and dor, as well as phenotypic interactions (reductions in eye pigment) between allels of lt and another eye-colour gene, garnet (g), whose gene product has close homology to a subunit of the human adaptor complex, AP-3.

Nuclear DNA content of 11 fungal species in Glomales

Abstract: The nuclear DNA content of 11 species of Glomales was evaluated by flow cytometry after DAPI staining relative to Gigaspora margarita, which was used as internal standard. The nuclear DNA content of this species was calibrated by propidium iodide staining relative to chicken red blood cells. A correction was applied when the difference in AT content of the DNA was significant between a sample and the standard. A single unimodal peak of fluorescence was observed for nuclei from the quiescent spores of the 11 fungal species studied. It was considered that this peak corresponded to the amount of DNA in the genome of each species. Important interspecific variations in DNA content per nucleus (1- to 8-fold) were observed among four species of the genus Scutellospora.Key words: nucleus, DNA content, flow cytometry, spore, Glomales.

Characterization of the tomato (Lycopersicon esculentum) genome using in vitro and in situ DNA reassociation

Abstract: A detailed in vitro study of the kinetics of DNA renaturation, i.e., a C0t analysis, can be used to determine the size of a genome, the relative proportions of single-copy and repetitive sequences,...

A complex arrangement of genes at a starch branching enzyme I locus in the D-genome donor of wheat

Abstract: Genomic DNA fragments from Triticum tauschii (D-genome donor to wheat) carrying starch branching enzyme I (SBE I) type genes have been characterized. One fragment contains one complete gene and two partial genes in 16 kb of DNA. One of the partial genes is oriented in the opposite strand to the other two. The gene that is complete was sequenced. Its structure corresponds closely to that of rice in that exons 3–8 are retained at similar sizes and spacings. A cDNA closely corresponding to the complete gene was isolated and characterized; it codes for a putative protein that represents a novel type of SBE I, as it is shorter at the 3′ end than the forms reported so far in other plants. A second genomic fragment contains a different SBE I gene. There appear to be approximately 10 copies of SBE I type genes in wheat (approximately 5 in T. tauschii) and most of them have been assigned to group 7 chromosomes. In situ hybridization indicates that a major locus for the genes is located at the distal end of the sho...

Isolation and chromosomal mapping of human glycogen synthase kinase-3 α and -3β encoding genes

Abstract: Glycogen synthase kinase-3 (GSK-3) is a serine-threonine kinase that exists as two isoforms, α and β, encoded by separate genes. Phosphorylation targets include a variety of cytoplasmic and nuclear proteins. Recent studies found that neurofilaments, amyloid precursor protein, and tau proteins are substrates of GSK-3 and that aberrant phosphorylation of these proteins is implicated in pathologies of the nervous system. To analyse the organisation of these two genes, a YAC library was screened by polymerase chain reaction, using primers specific for human GSK-3α and GSK-3β cDNA. Two clones, 220 and 285 kb in size, containing the complete GSK-3α coding sequence, and two clones, 365 and 285 kb in size, containing the 5 coding sequence of GSK-3β, were isolated. By somatic cell hybrid panel DNA amplification and radiation hybrid mapping, GSK-3α was found to be located at 19q13.2. On the other hand, by somatic cell hybrid panel DNA amplification and fluorescence in situ hybridisation using the 285-kb YAC clone, ...

Y chromosome specific markers and the evolution of dioecy in the genus Silene

Abstract: Sex determination in plants has been most thoroughly investigated in Silene latifolia, a dioecious species possessing heteromorphic sex chromosomes. We have identified several new Y chromosome linked RAPD markers and converted these to more reliable sequence characterized amplified region (SCAR) markers by cloning the RAPD fragments and developing longer primers. Of the primer pairs for seven SCARs, five amplify a single, unique fragment from the DNA of male S. latifolia. Two sets of primers also amplify additional fragments common to males and females. Homology between the X and Y chromosomes is sufficient to allow the amplification of fragments from females under less stringent PCR conditions. Five of the SCARs also distinguish between the sexes of closely related dioecious taxa of the section Elisanthe, but not between the sexes of distantly related dioecious species. These markers will be useful for continued investigations into the evolution of sex, phylogenetic relationships among taxa, and population dynamics of sex ratios in the genus Silene.

A study of variation in rDNA ITS regions shows that two haplotypes coexist within a single aphid genome

Abstract: We report variation in the rDNA internal transcribed spacers (ITSs) of aphid species, the first for these insects. Variation at 6 sites within ITS1 sequences of the green peach aphid, Myzus persicae, identified two haplotypes coexisting within the same individuals, indicating that molecular drive has not homogenised different copies of rDNA. During this study, we found that PCR can cause a precise 58-bp loss in the amplified copies of an ITS haplotype (type 1). This occurs in all detectable copies under routine PCR conditions, at different annealing temperatures and with Pfu and Taq polymerases. In addition, "hot-start" PCR exclusively copied a different, rare haplotype (type 2). These observations have important considerations for using PCR, as large deletions in PCR products may not reflect real deletions in the genome, and changes in PCR conditions may be needed to copy cryptic haplotypes.Key words: PCR, aphid, ITS, variation, selection.

Isolation and characterization of a satellite DNA family in the Saccharum complex

Abstract: EaCIR1, a 371-bp Erianthus-specific satellite DNA sequence, was cloned from TaqI restricted genomic DNA after agarose-gel electrophoresis. This sequence has 77% homology with a 365-bp satellite of Helictotrichon convolutum and 72% homology with a 353-bp tandem repeat sequence from Oryza sativa. PCR primers defined in the conserved regions of these repetitive sequences were used to isolate other satellite DNAs in different representatives of the Saccharum complex: SoCIR1 in Saccharum officinarum, SrCIR1 in Saccharum robustum, SsCIR1 and SsCIR2 in Saccharum spontaneum, and MsCIR1 in Miscanthus sinensis. EaCIR1 and SoCIR1 were localized to subtelomeric regions of the chromosomes by fluorescence in situ hybridization. Southern hybridization experiments, using two representatives of this repeat sequence family as probes, illustrated contrasting species-specificity and demonstrated the existence of similar repetitive elements in sorghum and maize.

Comparative mapping of the two wheat leaf rust resistance loci Lr1 and Lr10 in rice and barley

Abstract: The wheat genome is large, hexaploid, and contains a high amount of repetitive sequences. In order to isolate agronomically important genes from wheat by map-based cloning, a simpler model of the genome must be used for identifying candidate genes. The objective of this study was to comparatively map the genomic regions of two wheat leaf rust disease resistance loci, Lr1 and Lr10, in the putative model genomes of rice and barley. Two probes cosegregating with the Lr1 gene on chromosome 5DL of wheat were studied. The rice sequences corresponding to the two probes were isolated and mapped. The two probes mapped to two different rice chromosomes, indicating that the organization of the region orthologous to Lr1 is different in rice and wheat. In contrast, synteny was conserved between wheat and barley in this chromosomal region. The Lrk10 gene cosegregated with Lr10 on chromosome 1AS in wheat. The rice gene corresponding to Lrk10 was mapped on rice chromosome 1, where it occurred in many copies. This region ...

Genome-specific repetitive DNA and RAPD markers for genome identification in Elymus and Hordelymus.

Abstract: We have developed RFLP and RAPD markers specific for the genomes involved in the evolution of Elymus species, i.e., the St, Y, H, P, and W genomes. Two P genome specific repetitive DNA sequences, pAgc1 (350 bp) and pAgc30 (458 bp), and three W genome specific sequences, pAuv3 (221 bp), pAuv7 (200 bp), and pAuv13 (207 bp), were isolated from the genomes of Agropyron cristatum and Australopyrum velutinum, respectively. Attempts to find Y genome specific sequences were not successful. Primary-structure analysis demonstrated that pAgc1 (P genome) and pAgc30 (P genome) share 81% similarity over a 227-bp stretch. The three W genome specific sequences were also highly homologous. Sequence comparison analysis revealed no homology to sequences in the EMBL- GenBank databases. Three to four genome-specific RAPD markers were found for each of the five genomes. Genome-specific bands were cloned and demonstrated to be mainly low-copy sequences present in various Triticeae species. The RFLP and RAPD markers obtained, to...

Genetic mapping of Russian wheat aphid resistance genes Dn2 and Dn4 in wheat

Abstract: To obtain markers for marker-assisted breeding of Russian wheat aphid resistance in wheat (Triticum aestivum L.), resistance genes Dn2 and Dn4 were mapped with restriction fragment length polymorph...

Hatching out goldfish from common carp eggs: interspecific androgenesis between two cyprinid species

Abstract: We have successfully performed interspecific androgenesis between two cyprinid species. Gamma-ray irradiated eggs of common carp were fertilized with fresh and cryopreserved sperm of three different goldfish varieties and the haploid embryos were then heat-shocked to restore diploidy and to produce viable offspring. Androgenic diploid goldfish progenies from over a dozen different experiments were screened for four phenotypic markers several times. Color and other phenotypic markers characteristic of goldfish were found exclusively among androgenetic goldfish progenies; no markers originating from common carp were detected in over 1500 individuals investigated visually.RAPD assay was used to compare the parents and the offspring at the genomic level. The RAPD pattern of the androgenetic goldfish contained exclusively paternal bands, thereby confirming the results of the phenotypic analysis. According to our knowledge, this is the first successful interspecific androgenesis performed with two different species resulting in viable offspring.Key words: RAPD, whole genome manipulation, nuclear-mitochondrial incompatibility.

Development of a DNA marker for Vm, a gene conferring resistance to apple scab

Abstract: Primers of arbitrary sequence were screened by bulked segregant analysis to identify DNA fragments linked to Vm, a gene conferring resistance to apple scab (Venturia inaequalis). A 687-bp fragment ...

Suppressors of position-effect variegation in Drosophila melanogaster affect expression of the heterochromatic gene light in the absence of a chromosome rearrangement.

Abstract: Suppressors of position-effect variegation (Su(var)s) in Drosophila melanogaster are usually studied in the presence of chromosomal rearrangements, which exhibit variegated expression of euchromatic genes moved near to, or heterochromatic genes moved away from, centromeric heterochromatin. However, the effects of Su(var) mutations on heterochromatic gene expression in the absence of a variegating re-arrangement have not yet been defined. Here we present a number of results which suggest that Su(var) gene products can interact to affect the expression of the light gene in its normal heterochromatic location. We initially observed that eye pigment was reduced in several Su(var) double mutants; the phenotype resembled that of light mutations and was more severe when only one copy of the light gene was present. This reduced pigmentation could be alleviated by a duplication for the light gene or by a reduction in the amount of cellular heterochromatin. In addition, the viability of most Su(var) double mutant combinations tested was greatly reduced in a genetic background of reduced light gene dosage, when extra heterochromatin is present. We conclude that Su(var) gene products can affect expression of the heterochromatic light gene in the absence of any chromosomal rearrangements. However, it is noteworthy that mutations in any single Su(var) gene have little effect on light expression; we observe instead that different pairings of Su(var) mutations are required to show an effect on light expression. Interestingly, we have obtained evidence that at least two of the second chromosome Su(var) mutations are gain-of-function lesions, which also suggests that there may be different modes of interaction among these genes. It may therefore be possible to use this more sensitive assay of Su(var) effects on heterochromatic genes to infer functional relationships among the products of the 50 or more known Su(var) loci.

Mapping a gene conferring resistance to Pseudocercosporella herpotrichoides on chromosome 4V of Dasypyrum villosum in a wheat background

Abstract: The objectives of this study were to map and tag the previously undescribed eyespot resistance gene PchDv on chromosome 4V of Dasypyrum villosum in a wheat background. The 82 F2 plants used for mapping were produced from a cross between a susceptible wheat eYangmain5i (4V(4D)) substitution line and a resistant wheat eChinese Springi disomic addition line of chromosome 4V of D. villosum. Segregation for resistance and susceptibility among F2 plants was 3:1, indicating that resistance was controlled by a single dominant gene. PchDv mapped to the distal part of chromosome 4V and was bracketed by two RFLP markers, Xcdo949 and Xbcd588, in a 33-cM interval. This distance could not be reduced, owing to a lack of polymorphic loci in this region. Theoretically, double recombination in this region occurs in 3.3% of the individuals; therefore, 96.7% of the selected genotypes would have PchDv, with simultaneous selection for both flanking markers. Double recombination between the flanking markers was observed in 2 out of 82 (2.4%) F2 individuals.

The use of random amplified microsatellite polymorphic DNA and coefficients of parentage to determine genetic relationships in barley

Abstract: Seventy European barley lines (Hordeum vulgare ssp. vulgare) and 29 Hordeum vulgare ssp. spontaneum accessions were evaluated for random amplified microsatellite polymorphism (RAMP). PCR was performed with 5'-anchored primers complementary to microsatellites in combination with random primers. Of 20 primers assayed in barley, only 9 produced well-resolved fragment patterns in H. vulgare ssp. spontaneum. On the basis of 56 polymorphic fragments, genetic distances between the two subspecies were calculated. Barley samples were subdivided according to growth habit and spike morphology. The smallest genetic distance was found between winter cultivars and accessions of H. vulgare ssp. spontaneum. The 20 primers assayed in the barley lines produced 140 polymorphic fragments that were used to calculate genetic similarity between lines. Mean genetic similarity within groups of lines ranged from 0.693 for 6-rowed winter barley to 0.657 for 6-rowed spring barley. Within these groups, mean values were significantly ...

B-chromosome origin in the endemic New Zealand frog Leiopelma hochstetteri through sex chromosome devolution.

Abstract: The endemic New Zealand frog Leiopelma hochstetteri has variable numbers of mitotically stable B chromosomes. To assess whether the B chromosomes were derived from the autosome complement, they were isolated by micromanipulation and their DNA amplified by degenerate oligonucleotide primed PCR. Southern hybridizations of B chromosome DNA probes to genomic DNA from males and females characterized by differing numbers of B chromosomes demonstrated that the B chromosomes were derived from the univalent W sex chromosome characteristic of North Island populations. The presence of homologous B chromosome specific sequences from geographically distinct populations indicates a single origin of the B chromosomes. Furthermore, a primitive homology shared by B chromosomes and the W sex chromosome from an ancestral WZ/ZZ karyotype, which is still present in frogs from Great Barrier Island, shows that the B chromosomes originated soon after the univalent W sex chromosome had originated. Sequence analysis revealed that B chromosome DNA is composed of repeat sequences and has the potential to form stable hairpin structures. The molecular dynamics of these structures may reflect an inherent propensity to undergo rapid change in nucleotide sequence and chromosome structure.

Isolation and chromosomal mapping of human glycogen synthase kinase-3 alpha and -3 beta encoding genes.

Abstract: Glycogen synthase kinase-3 (GSK-3) is a serine-threonine kinase that exists as two isoforms, alpha and beta, encoded by separate genes. Phosphorylation targets include a variety of cytoplasmic and nuclear proteins. Recent studies found that neurofilaments, amyloid precursor protein, and tau proteins are substrates of GSK-3 and that aberrant phosphorylation of these proteins is implicated in pathologies of the nervous system. To analyse the organisation of these two genes, a YAC library was screened by polymerase chain reaction, using primers specific for human GSK-3 alpha and GSK-3 beta cDNA. Two clones, 220 and 285 kb in size, containing the complete GSK-3 alpha coding sequence, and two clones, 365 and 285 kb in size, containing the 5' coding sequence of GSK-3 beta, were isolated. By somatic cell hybrid panel DNA amplification and radiation hybrid mapping, GSK-3 alpha was found to be located at 19q13.2. On the other hand, by somatic cell hybrid panel DNA amplification and fluorescence in situ hybridisation using the 285-kb YAC clone, GSK-3 beta was mapped to 3q13.3.