bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of half-tetrad analysis to discriminate between two types of 2n egg formation in a potato haploid
Authors: Werner Joanna E. , Douches David S. , Freyre Rosanna
Published: April 2011

The ratio of the first division restitution (FDR) to second division restitution (SDR) 2n eggs was estimated in 4182t, a haploid (2n = 2x = 24) of Solanum tuberosum L. that produces 2n eggs by the two modes. The segregation of three genes previously mapped relative to their centromeres, Pgm-2 (2.0 cM), Mdh-1 (33.5 cM), and 6-Pgdh-3 (30.1 cM) was analyzed in the tetraploid offspring of a 2x × 4x cross. Based on the segregation of the Pgm-2 locus, 39.7% of the progeny originated from FDR 2n eggs and 60.3% from SDR. Segregation patterns of the two distal loci within the FDR-derived 4x subpopulation indicated that the gene–centromere recombination rate during megasporogenesis was significantly reduced for Mdh-1 when compared with a previous estimate during microsporogenesis. In the SDR-derived 4x subpopulation, the gene–centromere recombination rates for Mdh-1 and 6-Pgdh-3 were not significantly different from previous estimates. Tetraploid progeny generated from one 2x × 4x cross where the 2x parent produces 2n gametes by two modes can be used to make an unbiased comparison of the potential breeding value of FDR and SDR gametes.Key words: potato, megasporogenesis, first division restitution, second division restitution, isozyme.
A gene for embryo–endosperm compatibility and seed viability in alloplasmic Triticum turgidum
Authors: Maan S. S.
Published: April 2011

Alien cytoplasms have more deleterious effect on Triticum turgidum L. var. durum (2n = 28; 14 II; AABB) than on T. aestivum L. (2n = 42; 21 II; AABBDD). The species cytoplasm specific (scs) nuclear genes from the cytoplasm donor species and scs homoeoalleles ameliorate cytoplasmic effects in alloplasmic wheats. The D-genome chromosome(s) of T. aestivum must have a scs gene(s) that is absent in T. turgidum. Also, the dosage of scs homoeoalleles must be more favorable for nucleocytoplasmic compatibility (NCC) in 6x than 4x wheats. This paper reports that two genes, scs on 1DL telosome from T. aestivum 'Selkirk' and a vitality (Vi) gene from (Aegilops cylindrica) T. aestivum 'Selkirk', restored nucleocytoplasmic and embryo–endosperm compatibility, fertility, seed viability, and plant vigor in Ae. squarrosa and Ae. cylindrica 29-chromosome durum plants. In the absence of Vi, 29-chromosome plants set a few sporadic plump seed in selfed spikes but a few plump (about same number as in selfed spikes) and a large number of shrivelled seed in spikes crossed with euplasmic durum. Seed with Vi embryos were viable and those without Vi were nonviable. Similarly, Vi restored fertility to spontaneous aneuploids in the progeny of Ae. squarrosa 29-chromosome plants. Euploid sibs with Vi, but without 1DL telosome, had greatly reduced vigor. The control 'Selkirk' and durum wheats did not have Vi. Hence, Vi may have originated by mutation in Ae. cylindrica 'Selkirk' or Ae. cylindrica durum. Similar spontaneous changes may improve fertility in interspecific hybrid progeny and condition complex inheritance of fertility restoration in alloplasmic wheats.Key words: T. aestivum, Vi and scs genes, xenia effect, zygotic sterility, seed viability, nucleocytoplasmic compatibility, syndrome of cytoplasmic effects.
In situ digestion of barley chromosomes with restriction endonucleases
Authors: Kamisugi Y. , Ikeda Y. , Ohno M. , Minezawa M. , Fukui K.
Published: April 2011

In situ digestion of barley chromosomes with restriction endonucleases was examined. All the treatments with five restriction endonucleases, MboII, RsaI, HaeIII, HinfI, and DraII, showed various band patterns on the barley chromosomes. Differences were observed in the band patterns produced with different restriction endonucleases. Uneven staining patterns, similar to the band patterns by the endonuclease treatments, also appeared when the chromosomes were treated with the buffer solution without the enzyme. The band patterns observed both with and without the endonucleases were classified into the four types and the frequency of each type among the different treatments was investigated. The change of the band types along with treatment time was accelerated by the addition of the restriction endonuclease. As a result, it was concluded that there existed chromosome band patterns that were specific to the endonuclease treatments and that the buffer solution also affected to the production of the bands on the chromosomes.Key words: Hordeum vulgare L., chromosome band pattern, in situ digestion, restriction endonuclease, restriction banding.
The mitochondrial NADH dehydrogenase subunit 6 (ND6) gene in Murres: relevance to phylogenetic and population studies among birds
Authors: Moum Truls , Johansen Steinar
Published: April 2011

The nucleotide sequences of the mitochondrial ND6 and tRNAGlu genes and part of the displacement loop region in two closely related seabird species are presented. A chicken type gene organization in which the tRNAGlu, ND6, and displacement loop are localized next to each other was found in these species and suggests that this is a conserved feature of avian mitochondrial DNA. The nucleotide and amino acid divergences of ND6 at different taxonomic levels are assessed, and its relevance to phylogenetic studies in birds is discussed.Key words: mitochondrial DNA, phylogeny, bird, polymerase chain reaction.
Cold-sensitive chromosome regions and their relation to constitutive heterochromatin in Cestrum parqui (Solanaceae)
Authors: Berg C. , Greilhuber J.
Published: April 2011

The structural cause for cold-induced undercondensation of certain chromosome segments is still unknown, and no consistent cytochemical correlations have emerged as yet. Cestrum parqui belongs to one of the few plant genera having chromosomes with such cold-sensitive regions. In the present study, four heterochromatin classes were distinguished in the karyotype of this species by sequential fluorochrome staining with chromomycin A3, DAPI, and D 287/170, and C-banding, N-banding, and silver impregnation. (i) Cold-sensitive regions (CSRs): Banding behaviour indicates AT-rich constitutive heterochromatin. Silver impregnation occurs after cold-treatment from interphase to metaphase. CSRs are subject to polymorphisms. Quantitatively they are only a minor component of the band endowment. (ii) Nucleolar organizers: Two pairs were identified. Banding behaviour indicates GC-rich constitutive heterochromatin. The nucleolar constrictions proper are morphologically indistinct at mitotic metaphase and lose silver impregnation capability at that stage. (iii) Non-nucleolar CMA-positively fluorescent C-bands: There is only one polymorphic paracentromeric band in this class, (iv) Low-fluorescence N-bands. These show quenched fluorescence with all fluorochromes and occur as clusters of small bands scattered over all chromosome arms. This class of bands is quantitatively predominating. Dull fluorescence with both the "GC-specific" chromomycin and the "AT-specific" DAPI is an anomaly but not completely unknown in plants.Key words: Cestrum parqui, cold-sensitive regions, heterochromatin, chromosome banding, silver impregnation.
Evidence for the involvement of gene conversion in meiotic instability of the Rp1 rust resistance genes of maize
Authors: Hu Gongshe , Hulbert Scot
Published: April 2011

Rp1 is a complex rust resistance locus of maize. Susceptible recombinants can be observed at variable frequencies from different Rp1 heterozygotes and homozygotes by crossing-over and unequal crossing-over. In addition, susceptible progeny have been observed from one heterozygote that were not associated with crossing-over, as indicated by flanking marker analysis. We analyzed testcross progeny from this cross (Rp1-C/Rp1-J) and a related cross (Rp1-F/Rp1-J) to identify noncrossover type derivatives, to estimate their frequency, and to determine the mechanism by which they arise. Testcross progeny were screened sequentially with two different rust isolates to assay each gene individually. Both susceptible noncrossover types and those with the combined resistance of each parent were identified in approximately equal frequencies. Patterns of recombination indicated that the noncrossover type derivatives arose by gene conversion as opposed to mutation or intrachromosomal crossing-over. While gene conversion events were observed frequently in both crosses (approx. 7 × 10−4), they were less frequent than crossover derivatives. Key words: Puccinia, disease resistance, recombination, gene family, restriction fragment length polymorphism.
The origin of common laboratory mice
Authors: Nishioka Yutaka
Published: April 2011

The house mouse is one of the model organisms in genetics and more than 400 inbred strains have been established. However, many of the strains are related and their ancestry can be traced back to European fancy mice inbred in the 1920s. Recent molecular studies corroborate the early historical records that assert that Japanese fancy mice were introduced into European stocks and thus contributed to the development of "old" inbred strains. Consequently, many inbred strains have genomic DNA derived from more than one subspecies of Mus musculus. The subspecific hybrid origin of common inbred strains has important bearings on the interpretation of genetic data, and the limitations that history imposes upon the currently available strains make it necessary to establish new inbred strains representing specific wild populations.
The genetics of triploid formation and its relationship to endosperm balance number in potato
Authors: Johnston S. A. , Hanneman Jr. R. E.
Published: April 2011

The ability of Solanum tuberosum Group Andigena clones to produce triploids (2n = 3x = 36) in 4x(4 endosperm balance number (EBN)) × 2x(2EBN) crosses was investigated. The difference in triploid production among the clones tested, though large, appears to be the result of low heritability. The triploids produced in the 4x × 2x crosses did not seem to bear heritable factors that improved triploid production in 2x and 4x populations derived from them. Yet, the seeds/fruit data from a similar 4x × 2x cross fit a Poisson distribution. It was argued that the low probability nonheritable random events responsible for the triploids from 4x × 2x and 2x × 4x crosses were misfertilizations, mitotic abnormalities in the gametophyte, and (or) mitotic misdivisions in the endosperm.Key words: Solanum, endosperm, triploid block, fertilization.
A novel genetic interaction betweendaughterlessand a variegating rearrangement strain ofDrosophila melanogaster
Authors: Chakrabarti Dalia , Mukhopadhyay Somnath , Duttagupta Ashish K.
Published: April 2011

The effect of the maternal-effect mutation daughterless (da) on the reinverted In(1)BM2strain of Drosophila melanogaster has been evaluated cytogenetically. Results show that while the variegated nature of the single X chromosome of In(1)BM2(rv) males born to ♂ da/da × ♀ +/+ parents is suppressed, their female sibs, homozygous for the In(1)BM2(rv) chromosome, survive the lethal effect of the absence of da+product in their zygotes.Key words: Drosophila, variegation, modifier of variegation, position effect.
Meiotic variation in an intergenomic autopolyploid series. II. Pairing behaviour
Authors: Wallace A. J. , Callow R. S.
Published: April 2011

Pairing behaviour has been studied in PMCs of C0 autotetraploids of seven Lathyrus species exhibiting a range of genome size (10.8–19.9 pg DNA/2C). Each tetrasome within a C0 autotetraploid is equally likely to form a quadrivalent and the great majority of metaphase multivalents (96%) gave evidence of only a single synaptic exchange. Four components of variance in bivalent frequency were detected in the tetraploids. Both chiasma-dependent (0.5%) and chiasma-independent (4.2%) interspecific components were observed, whereas the only intraspecific component between plants (2.8%) was independent of variation in chiasma frequency. The only nonresidual component of variance in minimal incidence of synaptic exchange was interspecific (3.9%) and independent of variation in multivalent frequency.Key words: meiosis, chiasma frequency, autopolyploid, Lathyrus.
Physical mapping of the 5S rRNA multigene family in 6x triticale and rye: identification of a new rye locus
Authors: Cuadrado Angeles , Jouv Nicolas , Heslop-Harrison J. S.
Published: April 2011

In situ hybridization was used to physically map the 5S rRNA multigene family in three selected lines of hexaploid triticale and five lines of diploid rye. Using this technique, evidence for a new locus on the 3RS arm of the three triticale lines was first obtained, as well as confirmation of the presence of 5S rRNA loci on wheat and rye chromosomes of homoeologous groups 1 and 5. The new locus on the 3RS arm was confirmed in two lines of rye, Secale cereale L., although it was not present in the other rye varieties studied. We propose that the new 5S rRNA locus be referred to as 5SDna-R3.Key words: in situ hybridization, FISH, Secale, triticale, 5S rRNA genes.
Cloning of a DNA repeat element from horse: DNA sequence and chromosomal localization
Authors: Broad T. E. , Lewis P. E. , Pearce P. D. , Phua S. H. , Forrest J. W. , Pugh P. A. , Stewart-Scott I. A.
Published: April 2011

A DNA repeat element, revealed initially by digestion of horse DNA with TaqI, was cloned and characterized by Southern and in situ hybridization studies and nucleotide sequencing. The clone, e4/1, consisted of 32 tandem reiterations of a unit repeat of 21–22 bp, and produced multilocus DNA fingerprinting profiles that were useful for parentage analysis in horses. The tandem repeat element was shown by in situ hybridization to be localized in the centromeres of the acrocentric but not metacentric classes of horse chromosomes.Key words: Equidae, Equus caballus, DNA repeat, DNA fingerprinting, centromere.
Identification of the parental chromosomes of the wheat–alien amphiploid Agrotana by genomic in situ hybridization
Authors: Chen Qin , Conner R. L. , Laroche A.
Published: April 2011

Labelled total genomic DNA from four alien species, Thinopyrum ponticum (Host) Beauv. (2n = 70, genomes J1J1J1J2J2), Th. bessarabicum (Savul. &Rayss) Love (2n = 14, genome J), Th. elongatum (Host) Beauv. (2n = 14, genome E), and Haynaldia villosa (L.) Schur. (2n = 14, genome V), were used as probes in combination with blocking wheat DNA for in situ hybridization of the chromosomes of Agrotana, a wheat–alien hybrid (2n = 56) of unknown origin. The results showed that genomic DNA probes from Th. ponticum and Th. bessarabicum both clearly revealed 16 alien and 40 wheat chromosomes in Agrotana, indicating that the J genome present in these two species has a high degree of homology with the alien chromosomes in Agrotana. Biotinylated genomic DNA probe from Th. elongatum identified 10 chromosomes from Agrotana, while some regions of six other chromosomes yielded a weak or no signal. The probe from H. villosa produced no differential labelling of the chromosomes of Agrotana. The genomic formula of Agrotana was designated as AABBDDJJ. We suggest that the alien parent donor species of Agrotana is Th. ponticum rather than Th. bessarabicum. Genomic relationships of the three Thinopyrum species are discussed in relation to the distribution of GISH signals in the chromosomes of Agrotana.Key words: Thinopyrum species, wheat–alien amphiploid, genomic DNA probing, in situ hybridization, molecular cytogenetics.
Characterization of MboI satellites in Cirrhina mrigala and Clarias batrachus (Pisces)
Authors: Padhi Bhaja K , Ghosh Sudip K , Mandal Radha K
Published: April 2011

We have cloned and characterized two highly reiterated, tandemly repeated, and A + T rich MboI DNA fragments, one in Cirrhina mrigala (Cyprinidae), with a monomer size of 266 bp, and one in Clarias batrachus (Clariidae), with a monomer size of 227 bp. The MboI fragment in C. mrigala is species-specific and absent in other carps, such as Catla catla and Labeo rohita. The MboI fragment in C. batrachus was also present in two other catfishes tested, namely Clarias gariepinus and Heteropneustes fossilis. In C. mrigala xC. catla and C. mrigala x L. rohita hybrids, the C. mrigala specific MboI fragment is inherited uniparentally. In the reciprocal hybrids of C. batrachus xH. fossilis, the satellite ladder contains the bands of both parental species. The MboI satellite of carp may be useful in genetic introgression analysis and that of catfish in distinguishing between gynogenetic progeny and true hybrids.
Synteny with rice: analysis of barley malting quality QTLs andrpg4chromosome regions
Authors: Han F , Kleinhofs A , Ullrich S E , Kilian A , Yano M , Sasaki T
Published: April 2011

The barley (Hordeum vulgare L.) chromosome 1 centromere region contains two adjacent overlapping quantitative trait loci (QTLs) for malting quality traits, and the chromosome 7L subtelomere region contains the stem rust (causal agent Puccinia graminis f.sp. tritici) resistance gene rpg4. To facilitate the saturation mapping of these two target regions, a synteny-based approach was employed. Syntenic relationships between the barley target regions and the rice (Oryza sativa) genome were established through comparative mapping. The barley chromosome 1 centromere region was found to be syntenic with rice chromosome 8 and parts of rice chromosomes 3 and 10. A 6- to 15-fold difference in genetic distance between barley and rice in the syntenic region was observed, owing to the apparent suppressed recombination in the barley chromosome 1 centromere region. Barley chromosome 7L was found to be syntenic with rice chromosome 3. The establishment of synteny with rice in the two target regions allows well-established and characterized rice resources to be utilized in fine mapping and map-based cloning studies.Key words: genome synteny, quantitative trait loci, QTL, disease resistance gene, Triticeae.
Differential behavior ofSolanum brevidensribosomal DNA loci in a somatic hybrid and its progeny with potato
Authors: McGrath J Mitchell , Helgeson John P
Published: April 2011

Fluorescence in situ hybridization was used to characterize loci encoding ribosomal RNA (rDNA) among parents and progeny of a somatic fusion between tetraploid Solanum tuberosum (potato) and diploid Solanum brevidens. As expected, four major sites of hybridization to rDNA loci were evident in the tetraploid parent species, two in the diploid parent species, and six in the hexaploid somatic fusion plant. Two of the loci in the somatic fusion plant showed differential signals relative to the other four, which were interpreted as a delayed condensation of sites harboring the rDNA loci. This delayed condensation was heritable to the first backcross generation of the somatic hybrid crossed with potato. In the second backcross generation, differential condensation was not evident. However, a heterochromatic isochromosome was observed whose presence was correlated with a S. brevidens specific marker linked with the rDNA locus. It is suggested that the S. brevidens rDNA loci are preferentially affected in the somatic hybrid and its progeny, and that the delayed condensation may have contributed to the formation of the isochromosome.Key words: introgression, recombination, isochromosome, in situ hybridization.
The organization of the α-tubulin gene family in the Drosophila montium subgroup of the melanogaster species group
Authors: Drosopoulou Elena , Scouras Zacharias G
Published: April 2011

The α 1-, α 2-, α 3-, and α 4-tubulin genes have been mapped by in situ hybridization to the polytene chromosomes of five species representative of the Drosophila montium subgroup geographical distribution. A lambda phage clone containing α 1-tubulin specific sequences was isolated from a genomic DNA library of Drosophila auraria and its restriction endonuclease pattern is presented. Both well-characterized heterologous and homologous probes were used to assess orthogonality of gene members between species groups. The in situ hybridization pattern observed in all species studied is consistent with that of Drosophila melanogaster, since α 1-, α 2-, and α 3-tubulin genes are located on the same polytene arm, and the α 4-tubulin gene is found on a different arm. Cross-hybridization was observed among α 1-, α 2-, and α 3-tubulin specific sequences in all species studied, using either heterologous or homologous probes. However, unlike D. melanogaster, in all montium species studied, both α 1- and α 3-tubulin specific probes hybridize to the same polytene band, indicating a clustered organization of the above genes. The chromosomal organization of this gene family would suggest that taxa within the montium subgroup are closer to their common ancestor than are the taxa in the melanogaster species group. A mode of evolution for this gene family in Drosophila is proposed. Key words: α -tubulin genes, evolution, gene cluster, gene dispersion, Drosophila montium subgroup.
Genome analysis of Thinopyrum intermedium and Thinopyrum ponticum using genomic in situ hybridization
Authors: Chen Qin , Conner R L , Laroche A , Thomas J B
Published: April 2011

Genomic in situ hybridization (GISH) using genomic DNA probes from Thinopyrum elongatum (Host) D.R. Dewey (genome E, 2n = 14), Thinopyrum bessarabicum (Savul. & Rayss) Á. Löve (genome J, 2n = 14), and Pseudoroegneria strigosa (M. Bieb.) Á. Löve (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.Key words: genomic in situ hybridization, GISH, Thinopyrum intermedium, Thinopyrum ponticum, genomic analysis, Js genome.
Insertional polymorphism in introns 4 and 10 of the maize ß-glucosidase gene glu1
Authors: Esen Asim , Bandaranayake Hema
Published: April 2011

The major ß-glucosidase isozyme Glu1 is encoded by a highly polymorphic gene (glu1) in maize. The glu1 gene comprises 12 exons and 11 introns. Two of these introns, introns 4 and 10, show insertional polymorphism: those in allele glu1-1 (represented by inbred line OH7B) are longer than those in other inbred genotypes and in two teosintes (Zea mexicana and Zea parviglumis) surveyed. Sequence data revealed that an increase in the length of intron 4 from 150 to 477 bp in OH7B is due to a short (11 bp) tandem duplication and a large insertion sequence of 313 bp plus a 4-bp (5 ATAG 3) direct repeat. The 313-bp insertion sequence (referred to as mzsTn-1) has all the features of a transposon, having a 25-bp well-conserved (3/25 mismatches) inverted repeat sequence at its termini flanked by a 4-bp direct repeat. The increase in length from 1041 to 1302 bp in intron 10 of OH7B is due to a 259-bp insertion sequence (referred to as mzsTn-2) plus a 2-bp (5 TA 3) direct repeat. The mzsTn-2 element also possesses all the hallmarks of a transposon: a 34-bp well-conserved (3/34 mismatches) inverted repeat sequence at its termini flanked by a 2-bp direct repeat. The mzsTn-1 element belongs to a new family of inverted repeat elements, while mzsTn-2 belongs to the Stowaway family of inverted repeat elements. Analysis of PCR products from amplifications off genomic-DNA templates, using primers derived from the inverted repeat termini, and Southern blotting data suggest that both small transposons are members of a multigene family. The occurrence of two different small transposons in introns of the same glu1 allele in inbred OH7B and their absence in other genotypes suggest that they have moved into this glu1 allele recently through mediation of their autonomous counterparts that are active in OH7B or in its ancestry.Key words: ß-glucosidase, maize, intron, small transposon, polymorphism.
Transgenic analysis of the cSOD-null phenotypic syndrome in Drosophila
Authors: Parkes T L , Kirby K , Phillips J P , Hilliker A J
Published: April 2011

Cu-Zn superoxide dismutase (cSOD) is an enzyme of critical importance for the inactivation of superoxide radicals generated by cellular metabolic processes. A phenotypic syndrome has been characterized for homozygotes for a null mutation of the Drosophila cSOD gene, many features of which may be relevant to current studies of cSOD mutations in mammals. However, it was possible that some of the features of this syndrome were at least partially attributable to genetic background differences between control and mutant strains. The results reported in this paper document that the previously described features of the cSOD-null phenotype, namely (i) adult sensitivity to paraquat, (ii) male sterility, (iii) female semisterility, (iv) adult life-span reduction, (v) adult hyperoxia sensitivity, (vi) larval radiation sensitivity, and (vii) developmental sensitivity to glutathione depletion, are all rescued by a cSOD+ transgene in a controlled cSOD-null genetic background. This clearly confirms that the phenotype is largely attributable to the cSOD mutation per se. We describe two new features of the cSOD-null phenotype, namely (viii) adult sensitivity to glutathione depletion, and (ix) adult sensitivity to ionizing radiation, which are ameliorated by the cSOD+ transgene. The distinct sensitivity of cSOD-deficient individuals, and the uniform resistance of the cSOD+ control strains, clearly establish the requirement for cSOD in protection against intrinsic and applied oxygen stress and set the stage for tissue-specific expression studies with the goal of elucidating the critical target(s) of damage in cSOD-deficient animals.Key words: Cu-Zn superoxide dismutase, oxygen defense, glutathione, ionizing radiation, genetic background.
Isolation and preliminary characterization of histone H1.b allelic variants from quail erythrocytes
Authors: Palyga Jan , Neelin James M
Published: April 2011

Our goal was to purify and characterize the allelic variants H1b1 and H1b2 of histone H1.b, one of the seven subtypes of this linker histone extracted from Japanese quail erythrocyte nuclei. These variants are revealed phenotypically as band H1.3 or part of band H1.4 by polyacrylamide gel electrophoresis (PAGE) in sodium dodecyl sulfate (SDS). All H1 subtypes together were separated from H5 by gel-permeation chromatography through Bio-Gel P-150. H1 was then fractionated on a column of the cation-exchange resin Amberlite CG-50 by using a shallow guanidine hydrochloride gradient, which enriched subtype H1.b together with H1.z and overlapping with subtypes H1.a and H1.b. Alternatively purification of subtypes was achieved electrophoretically: total H1 fractions from quail with different H1 phenotypes were first resolved into sub-types by PAGE in acetic acid - urea; after staining, the appropriate H1.b bands from several parallel gel pieces were excised and the histone was concentrated by PAGE in SDS. After fragmentation of H1.b in the gel pieces with N-bromosuccinimide (NBS), PAGE in SDS indicated no difference between H1b1 and H1b2 in the C-terminal "half" of the polypeptides. In contrast, limited digestion with endoprotease V8 from Staphylococcus aureus has shown that differences, probably by a few residues in length, reside in the N-terminal part of the molecule, close to the amino-terminus.Key words: quail histone H1.b, electrophoretic fractionation, linker histone variant.
Genetic mapping of Hessian fly avirulence gene vH6 using bulked segregant analysis
Authors: Stuart J J , Schulte S J , Hall P S , Mayer K M
Published: April 2011

The Hessian fly, Mayetiola destructor (Say), an important insect pest of wheat, Triticum aestivum L., has a gene-for-gene relationship with wheat: single genes in the insect condition avirulence to specific resistance genes in wheat. We report the discovery of the first molecular genetic marker that is tightly linked to a Hessian fly avirulence gene. This dominant DNA polymorphism (OPG15-1) was identified using bulked segregant analysis and arbitrary primers in polymerase chain reactions. Bulked segregant analysis was modified to accommodate the anomalous chromosome cycle of the Hessian fly. It was used to identify DNA polymorphisms linked to the gene (vH6) that confers avirulence to the resistance gene H6 in wheat. OPG15-1 was cloned and sequenced, and a pair of site-specific primers were designed that converted it into a codominant single-stranded conformational polymorphism. Both OPG15-1 and vH6 were shown to be X-linked, and the genetic distance between the two loci was 2.5 ± 2.5 cM. In situ hybridization to polytene chromosomes of larval salivary glands indicated that OPG15-1 resides near the centromere of Hessian fly chromosome X1.Key words: Mayetiola destructor, avirulence gene, RAPD-PCR, bulked segregant analysis, single-stranded conformational polymorphism, SSCP, in situ hybridization.
Isolation and chromosomal mapping of human glycogen synthase kinase-3 α and -3β encoding genes
Authors: Shaw Pang-Chui , Davies Angela F , Lau Kwok-Fai , Garcia-Barcelo Merce , Waye Mary MY , Lovestone Simon , Miller Christopher CJ , Anderton Brian H
Published: April 2011

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, GSK-3β was mapped to 3q13.3.Key words: Alzheimer's disease, fluorescence in situ hybridisation, glycogen synthase kinase, neurodegeneration, radiation hybrid mapping, yeast artificial chromosome.
The activity of nucleolar organizing chromosomes in multigeneric F1 hybrids involving wheat, triticale, and tritordeum
Authors: Lima-Brito J , Guedes-Pinto H , Heslop-Harrison J S
Published: April 2011

The nucleolar activity in interspecific hybrids between tritordeum, wheat, and triticale was studied using the silver salt - nylon technique. rRNA genes from the major NORs from wheat (chromosome pairs 1B and 6B) and Hordeum chilense (chromosome pairs 5Hch and 6Hch) were active in genomic constitutions AABBHchHch, AABBHch, and AABBDHch. The rye chromosome 1R NOR suppression found in triticale and in wheat × rye F1 hybrids is also observed in trigeneric hybrids, genome constitution AABBRHch, derived from crosses between triticale and tritordeum. As expected, the maximum number of NORs per metaphase cell is coincident with the maximum number of nucleoli per interphase cell. Occasional extra nucleolar activity was observed, probably owing to minor sites of wheat NORs, since no other sites of active or inactive rRNA genes were detected in H. chilense. However, it is notable that the two H. chilense loci and two major rDNA loci of wheat origin are expressed together.Key words: silver staining, rDNA, nucleolar dominance, interspecific hybrids, Triticum aestivum, Triticum durum, Hordeum chilense, triticale, tritordeum.
A superfamily of disease resistance gene analogs is located on all homoeologous chromosome groups of wheat (Triticum aestivum)
Authors: Spielmeyer W , Robertson M , Collins N , Leister D , Schulze-Lefert P , Seah S , Moullet O , Lagudah E S
Published: April 2011

In this study, resistance gene analogs (RGAs) which were isolated from monocot crop species (wheat, barley, maize and rice) and contained conserved sequence motifs found within the nucleotide binding site - leucine rich repeat (NBS-LRR) class of resistance genes, were used to assess their distribution in the wheat genome. The RGAs showed 30-70% amino acid identity to a previously isolated monocot NBS-LRR sequence from the Cre3 locus for cereal cyst nematode (CCN) resistance in wheat. We used the RGAs as probes to identify and map loci in wheat using recombinant inbred lines of an international Triticeae mapping family. RGA loci mapped across all seven homoeologous chromosome groups of wheat. This study demonstrated that the RGA mapping approach provides potential entry points toward identifying resistance gene candidates in wheat.Key words: wheat, disease resistance genes, nucleotide binding site, leucine rich repeat, resistance gene analogs.
Hatching out goldfish from common carp eggs: interspecific androgenesis between two cyprinid species
Authors: Bercsényi Miklós , Magyary István , Urbányi Béla , Orbán László , Horváth László
Published: April 2011

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.
Abundance and variation of microsatellite DNA sequences in beans (Phaseolus andVigna)
Authors: Yu Kangfu , Park Soon J , Poysa Vaino
Published: April 2011

Microsatellites or simple sequence repeats (SSRs) have been demonstrated to be abundant and hypervariable in some eukaryotic genomes. Although the presence of microsatellites is very well documented in many plant species, no information on microsatellites in beans (Phaseolus andVigna) is available. To assess the abundance and usefulness of bean microsatellites as genetic markers, 326 DNA sequences from the GenBank databases were searched. Sixty-one simple repetitive DNA sequences with 23 different types of repetitive DNA motifs were identified as potential microsatellites. Among these were 49 microsatellites from common bean (Phaseolus vulgaris) entries and 12 microsatellites from the genus Vigna. The most abundant type of microsatellite found in this search was that with di-nucleotide repeats of AT/TA. Microsatellites with tri- and tetra-nucleotide motifs were also identified. PCR analysis of 12 of the microsatellite-containing loci revealed that 11 of the 12 primer pairs could produce easily-scorable fragments, or groups of fragments. Allelic variation of the 11 loci was surveyed in 12 common bean inbred lines representing a diversity of germplasms. Seven of the 11 microsatellite loci were polymorphic and yielded 2-10 alleles. Analyses of the polymorphic loci in a common bean F6 recombinant inbred population showed that each segregated in a Mendelian fashion.Key words: microsatellite, simple sequence repeat, molecular marker, bean.
PCR-based analysis of the intergenic spacers of the Nor loci on the A genomes of Triticum diploids and polyploids
Authors: Sallares Robert , Brown Terence A
Published: April 2011

We present DNA sequence data showing population variation in the intergenic spacer (IGS) regions of the ribosomal DNAs (rDNAs) on the A genomes of 27 diploid and polyploid wheats. PCRs (polymerase chain reactions) specific for the Am genome gave products with five populations of Triticum monococcum but did not give products with AABB or AABBDD wheats. PCRs specific to the Au genome of T. urartu gave products with all the AABB and AABBDD polyploids that were tested, but not with T. monococcum. AAGG tetraploids gave products only with the Au-specific primers, but the AAAAGG hexaploid T. zhukovskyi gave products with both the Au and Am primers. Phylogenetic analysis showed a substantial degree of IGS divergence for both the Am and Au genomes in diploids and polyploids compared with other genomes of Triticum and Aegilops. The rate of evolution of the IGS is much greater than previously reported for the internal transcribed region of the rDNAs but the view that the IGS only gives random noise is rejected, the IGS sequences presented here reflecting the general evolutionary trends affecting the wheat genome as a whole.Key words: wheat, ribosomal DNA, intergenic spacer, polymerase chain reaction.
High resolution map around the vrs1 locus controlling two- and six-rowed spike in barley, Hordeum vulgare
Authors: Komatsuda Takao , Li Wenbin , Takaiwa Fumio , Oka Seibi
Published: April 2011

The vrs1 (formerly v) locus in the long arm of chromosome 2H controls lateral spikelet development in barley. The vrs1 locus was mapped by backcross-derived lines that consisted of 373 BC7F1 plants and 278 BC6F2 plants. The linkage study indicated that MWG801, CMNA-38/700, cMWG699, vrs1 and MWG865 exist in the order listed, with map distances of 3.1, 0.4, 0.1, and 0.9 centimorgans (cM), respectively. Recombination in female and male meiocytes showed no significant difference within this region. In a neighboring region between MWG865 and MWG503, the recombination frequency was higher in female than male meiocytes in one mapping population. The combined linkage data obtained from this study were compared with published data, and genotype-specific suppression of crossing-over was not evident in the vrs1 region.Key words: vrs1 locus (two- vs. six-rowed), molecular marker, recombination, backcross, Hordeum vulgare.
Phylogenetic reconstruction based on low copy DNA sequence data in an allopolyploid: The B genome of wheat
Authors: Blake Nancy K , Lehfeldt Ben R , Lavin Matt , Talbert Luther E
Published: April 2011

Study of bread wheat (Triticum aestivum) may help to resolve several questions related to polyploid evolution. One such question regards the possibility that the component genomes of polyploids may themselves be polyphyletic, resulting from hybridization and introgression among different polyploid species sharing a single genome. We used the B genome of wheat as a model system to test hypotheses that bear on the monophyly or polyphyly of the individual constituent genomes. By using aneuploid wheat stocks, combined with PCR-based cloning strategies, we cloned and sequenced two single-copy-DNA sequences from each of the seven chromosomes of the wheat B genome and the homologous sequences from representatives of the five diploid species in section Sitopsis previously suggested as sister groups to the B genome. Phylogenetic comparisons of sequence data suggested that the B genome of wheat underwent a genetic bottleneck and has diverged from the diploid B genome donor. The extent of genetic diversity among the Sitopsis diploids and the failure of any of the Sitopsis species to group with the wheat B genome indicated that these species have also diverged from the ancestral B genome donor. Our results support monophyly of the wheat B genome.Key words: wheat evolution, phylogenetics, DNA sequencing.
Evidence for evolutionary conservation of a physical linkage between the human BAF60b, a subunit of SWI/SNF complex, and thyroid hormone receptor interacting protein-1 genes on chromosome 17
Authors: Surabhi Rama Mohan , Daly Lisa Dawn , Cattini Peter A
Published: April 2011

The ubiquitously expressed rat BAF60b gene, which codes for a subunit of the multiprotein SWI/SNF complex, was recently identified between the pituitary growth hormone (GH-N) and thyroid hormone receptor interacting protein-1 (TRIP-1) genes. In primates, duplication of the GH-N gene has resulted in the addition of four placenta-specific (GH-V, CS-A, CS-B, and CS-L) genes downstream of the GH-N gene. As part of our study of the effect of remote sequences on the transcriptional regulation of the GH/CS gene family, we showed recently that these genes lie 40 kb upstream of the human TRIP-1 gene. We have now investigated the presence of the human BAF60b gene upstream of the TRIP-1 gene for evidence of evolutionary conservation of this arrangement or its disruption by the recent duplication of the nearby GH-N gene in primates. We report that, as in the rat genome, the human BAF60b gene is in the reverse transcriptional direction relative to the TRIP-1 gene, such that their polyadenylation sites are separated by 93 bp which compares with 92 bp in the rat. Reexamination of reported porcine TRIP-1 sequences also revealed the presence of the BAF60b gene separated by 93 bp, supporting an evolutionary conservation of this arrangement.Key words: P1 clone, gene mapping, downstream gene.
Mapping of theDioscorea tokorogenome: AFLP markers linked to sex
Authors: Terauchi Ryohei , Kahl Günter
Published: April 2011

Two framework linkage maps were constructed for the genome of the dioecious wild yam species Dioscorea tokoro. The pseudo-testcross strategy was employed, using 271 amplified fragment length polymorphisms (AFLPs), five sequence-tagged microsatellite sites, one isozyme, and one morphological marker. For the two parents DT7 and DT5 used in the cross, 13 and 12 linkage groups, respectively, were identified. The total map lengths were 669 and 613 cM, respectively, for DT7 and DT5, which cover more than 75% of the D. tokoro genome. Ten AFLP markers heterozygous only in the male parent showed tight linkages with the sex of its progeny, which suggests that male is the heterogametic sex (XY) and the female is the homogametic sex (XX).Key words: Dioscorea tokoro, yam, linkage map, AFLP, sex determination.
QTL analysis of Na+and Cl-accumulation related traits in an intergeneric BC1progeny ofCitrusandPoncirusunder saline and nonsaline environments
Authors: Tozlu Ilhami , Guy Charles L , Moore Gloria A
Published: April 2011

The effects of salinization with 40 mM NaCl on Poncirus trifoliata (L.) Raf., Citrus grandis (L.) Osb., their F1, and a BC1progeny population (C. grandis × (F1)) were investigated by means of Na+and Cl-analyses and QTL (quantitative trait loci) mapping. A total of 38 traits related to different tissue or whole-plant Na+and (or) Cl-accumulation was analyzed in salinized and nonsalinized BC1progeny clones. The comparison of the three parental types with the BC1progeny under control and saline conditions showed that the BC1progeny plants segregated transgressively for many traits. First mapping analyses resulted in a total of 73 potential quantitative trait loci (PQTL) with LOD scores [Formula: see text]3.0 located on a previously generated linkage map. Fifty-three percent of the mapped PQTLs were for traits associated with salinity. The small progeny population size used made further analyses of these PQTLs necessary. By considering LOD scores, map locations, and correlation analyses of the traits, it was possible to identify 17 regions of the citrus genome of interest: 8 of them may contain genuine QTLs of large effect and 9 regions are worthy of further study. Correlation analyses and locations of PQTLs indicated that many traits were controlled by fewer genes than the actual number of QTLs mapped for them. For example, 21 PQTLs mapped for Na+accumulation and Cl-/Na+ratios were located in a cluster at the beginning of one linkage group (LG), while 10 PQTLs mapped for Cl-accumulation and Cl-/Na+ratios were located in a cluster at the beginning of another LG. This is the first step in identifying QTLs that have a major impact on salt tolerance and (or) mineral accumulation in citrus.Key words: Citrus grandis, Poncirus trifoliata, salinity stress, QTL mapping, transgressive segregation, mineral analysis, sodium, chloride, salt tolerance, citrus genetics.
Chromosomal organization of a sequence related to LTR-like elements of Ty1-copia retrotransposons in Avena species
Authors: Linares Concha , Serna Antonio , Fominaya Araceli
Published: April 2011

A repetitive sequence, pAs17, was isolated from Avena strigosa (As genome) and characterized. The insert was 646 bp in length and showed 54% AT content. Databank searches revealed its high homology to the long terminal repeat (LTR) sequences of the specific family of Ty1-copia retrotransposons represented by WIS2-1A and Bare. It was also found to be 70% identical to the LTR domain of the WIS2-1A retroelement of wheat and 67% identical to the Bare-1 retroelement of barley. Southern hybridizations of pAs17 to diploid (A or C genomes), tetraploid (AC genomes), and hexaploid (ACD genomes) oat species revealed that it was absent in the C diploid species. Slot-blot analysis suggested that both diploid and tetraploid oat species contained 1.3 × 104 copies, indicating that they are a component of the A-genome chromosomes. The hexaploid species contained 2.4 × 104 copies, indicating that they are a component of both A- and D-genome chromosomes. This was confirmed by fluorescent in situ hybridization analyses using pAs17, two ribosomal sequences, and a C-genome specific sequence as probes. Further, the chromosomes involved in three C-A and three C-D intergenomic translocations in Avena murphyi (AC genomes) and Avena sativa cv. Extra Klock (ACD genomes), respectively, were identified. Based on its physical distribution and Southern hybridization patterns, a parental retrotransposon represented by pAs17 appears to have been active at least once during the evolution of the A genome in species of the Avena genus.Key words: chromosomal organization, in situ hybridization, intergenomic translocations, LTR sequence, oats.