bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and distribution of an interspersed repeated nucleotide sequence from Lophopyrum elongatum and mapping of a segregation-distortion factor with it
Authors: Zhang Hong-Bin , Dvořák Jan
Published: April 2011

Repeated nucleotide sequence pLeUCD2 cloned from Lophopyrum elongatum is highly abundant in the genomes of diploid and polyploid wheatgrass species of genera Lophopyrum, Thinopyrum, Pseudoroegneria, Agropyron, Elymus, Elytrigia, and Pascopyrum but undetectable by Southern blot hybridization in Triticum and representative species of Dasypyrum, Hordeum, Psathyrostachys, Secale, Taeniatherum, Heteranthelium, and Leymus in the tribe Triticeae. The DNA fragment inserted in pLeUCD2 is 277 bp long and AT rich (65%), and contains numerous inverted and palindromic repeats. In situ DNA hybridization substantiated a previous hypothesis that the sequence is interspersed in the wheatgrass genomes. Heterogeneity and clustering of like repeats of the pLeUCD2 family along wheatgrass chromosomes was used to map a segregation-distortion factor, designated Sd-1, proximal to the Lr19 locus in recombinant chromosomes of L. ponticum chromosome 7Ag and wheat chromosome 7D.Key words: gene transfer, chromosome manipulation, Triticeae, in situ hybridization, meiotic drive.
Chromosome polymorphism in Holochilus venezuelae (Rodentia: Cricetidae): C- and G-bands
Authors: Sangines N. , Aguilera M.
Published: April 2011

Karyological analysis of C- and G-banding patterns of 44 specimens of Holochilus venezuelae revealed six distinct karyomorphs, which were designated as follows: I (2n = 44; fundamental number (FN) = 56); II (2n = 45; FN = 58); IV (2n = 43; FN = 56);V(2n = 44; FN = 58); IV-a(2n = 42; FN = 56); and V-a (2n = 44; FN = 58). This chromosomal polymorphism is interpreted as the result of (i) one or two Robertsonian changes of the centric-fusion type, originating from one member of chromosome pair 10 and one of pair 11 (in karyotypes IV and V) and two metacentric chromosomes from pairs 10 and 11 (in karyotype IV-a); (ii) one pericentric inversion (in karyotype V-a) forming one submetacentric chromosome from the metacentric fusion product described above; and (iii) the presence of B chromosomes, which are almost completely heterochromatic and do not pair with any member of group A. The pattern of C-banding reveals that the first five pairs of metacentric chromosomes contain very little centromeric heterochromatin, while pair 6 and the fusion chromosomes (10/11 F) present a thick band. Extensive homology was found between G-banding patterns of Holochilus brasiliensis from Brazil and H. venezuelae. These facts support the hypothesis of a karyotypic evolution via centric fusions previously proposed for this genus.Key words: accessory chromosome, C- and G-banding, polymorphism, Holochilus venezuelae.
Inheritance of a mutable phenotype that is activated in alfalfa tissue culture
Authors: Ray I. M. , Bingham E. T.
Published: April 2011

Mutable alleles, typically regulated by transposable elements, have been identified in a number of plant species. Tissue culture induced genomic shocks may activate such elements. A mutable recessive condition arose in tissue culture of alfalfa and was highly unstable in subsequent cycles of culture. The mutable allele, designated c2-m4, is allelic to the C2 locus, a basic color factor locus involved in anthocyanin synthesis. Current research has focused on the inheritance and instability of c2-m4 in new genetic backgrounds as well as on dosage effects of the allele. We have confirmed a previous report that c2-m4 reverts to function at much higher frequencies in vitro (reversion frequency ca. 0.23) than in planta (reversion frequency < 0.001). Over sexual generations c2-m4 continues to be unstable. Transmission of the mutable phenotype to selfed, testcross, and F2 populations demonstrated monofactorial inheritance patterns (P > 0.25). In populations expected to have some plants carrying two or more c2-m4 alleles, individuals were found that reverted in vitro at significantly higher frequencies than their parent (0.67 ± 0.04 and 0.44 ± 0.08 versus 0.20 ± 0.09). In planta reversion also increased with increasing c2-m4 dosage. Preliminary evidence indicates that as c2-m4 dosage increases, each allele maintains its original capacity to revert.Key words: somaclonal variation, transposable element, tissue culture, mutable allele.
A comparison of polytene chromosomes in salivary glands and orbital bristle trichogen cells in Ceratitis capitata
Authors: Zacharopoulou A. , Bourtzis K. , Kerremans Ph.
Published: April 2011

The banding patterns of polytene chromosomes in different tissues of the Mediterranean fruit fly, Ceratitis capitata, vary to such an extent that homologous chromosomes cannot be recognised. However, analyses of autosomal breakpoints in several translocation strains allowed chromosomes from the two tissues to be aligned despite their difference in banding pattern. These results were discussed, considering the different hypotheses of the origin and biological significance of polytene chromosome bands.Key words: polytene chromosomes, salivary gland chromosomes, orbital bristle trichogen cell chromosomes, Ceratitis capitata.
Hybrid between durum wheat and diploid Thinopyrum bessarabicum
Authors: Jauhar Prem P.
Published: April 2011

Gross morphological features and chromosome association of the first triploid intergeneric hybrid (2n = 3x = 21; ABJ genomes) between durum wheat, Triticum turgidum L. (2n = 4x = 28; AABB), and diploid wheatgrass, Thinopyrum bessarabicum (Savul. &Rayss) A. Löve (2n = 2x = 14; JJ), are described. Genome relationships are assessed in the presence of the pairing homoeologous gene, Ph1. The hybrid was intermediate in phenotype between the two parents. It inherited the tillering habit, perennial growth habit, and glaucous leaves and stems from the male Thinopyrum parent; spike density and awns of wheat were partially expressed. An average of 13.67% of the chromosome complement paired in metaphase I cells of the hybrid. Mean chromosome associations were 0.07 III + 0.03 ring II + 1.30 rod II + 18.13 I and 1.51 chiasmata per cell, with a mean arm-pairing frequency, c, of 0.107. Because chromosomes of the A and B genomes show very little pairing with each other in the polyhaploids of T. turgidum, it was inferred that most of the bivalents in the hybrid were formed between chromosomes of the A and J and (or) B and J genomes, a welcome feature from the breeding standpoint. Trivalent frequency, albeit low, further indicated intergenomic pairing among A, B, and J. Associations between wheat and Thinopyrum chromosomes may permit intergeneric transfer of genes, which may be accelerated by the use of the ph1c ph1c homoeologous pairing mutant of durum wheat.Key words: intergeneric hybrid, chromosome pairing, genome relationship, Triticum, Ph1 pairing regulator.
Banded karyotype of a wild-caught male Korean raccoon dog, Nyctereutes procyonoides koreensis
Authors: Wada M. Y. , Lim Y. , Wurster-Hill D. H.
Published: April 2011

Chromosomes of a wild-caught male Korean raccoon dog (Nyctereutes procyonoides koreensis) were analyzed by conventional stain, G-banding and C-banding techniques. The basic karyotype of this subspecies is composed of metacentric (M) and acrocentric (A) chromosomes plus a variable number of B chromosomes (2n = 54 (= 10M + 42A + XY or XX) + Bs) and is the same as that of the Chinese and Finnish raccoon dogs (Nyctereutes procyonoides procyonoides). Karyotypes of the four subspecies of Nyctereutes procyonoides investigated to date conform to one of two types, the continental and the island. All animals from mainland Asia and eastern Europe that have been examined have the continental karyotype (2n = 54 (= 10M + 42A + XY or XX) + Bs), whereas all those from the four major Japanese islands that have been examined have the island type (2n = 38 (= 26M + 10A + XY or XX) + Bs). The two karyotypes have the same fundamental number (chromosomal arm number) of 66, and complete arm homology. However, the phylogenetic and taxonomic significance of the two distinct karyotypes within this monospecific genus is still unclear.Key words: raccoon dog, Nyctereutes, chromosomes, phylogeny, taxonomy.
Population cytogenetics of Austrosimulium bancrofti (Diptera: Simuliidae) in eastern Australia
Authors: Ballard J. W. O. , Bedo D. G.
Published: April 2011

Larvae of Austrosimulium bancrofti (Taylor) from four sites in eastern Australia were cytologically examined. Evidence for eight cytoforms is presented. These are A. bancrofti Ipswich A and B, A. bancrofti Willawarin, A. bancrofti Canberra, and A. bancrofti Eidsvold A, B, C, and D. Austrosimulium bancrofti Ipswich A, A. bancrofti Willawarin, and A. bancrofti Canberra were not collected in sympatry, but they showed fixed chromosomal inversion differences, unique sex-determining systems, and floating inversions. Larvae of A. bancrofti Ipswich A were collected in sympatry with A. bancrofti Ipswich B and A. bancrofti Eidsvold A, B, C, and D. However, low numbers of A. bancrofti Ipswich B and A. bancrofti Eidsvold A, B, C, and D were sampled. In sympatry these cytoforms are either positively assortatively mating or randomly mating. The data suggest that A. bancrofti is a complex of at least eight sibling species. Further sampling at sites intermediate to those reported here is necessary to confirm this hypothesis.Key words: Simuliidae, Austrosimulium, sibling species.
Variation of molecular markers among geographically diverse accessions of Triticum tauschii
Authors: Lubbers E. L. , Gill K. S. , Cox T. S. , Gill B. S.
Published: April 2011

Triticum tauschii (Coss.) Schmal. (genome DD), a diploid progenitor of hexaploid wheat (Triticum aestivum L.; AABBDD), grows across large areas of southwest Asia and contains more genetic variability for disease and insect resistance, isozymes, and seed storage proteins than the D genome of T. aestivum. To study patterns of variability at a large number of loci, we determined restriction fragment length polymorphism genotypes at 25 loci in a germ-plasm collection of 102 T. tauschii accessions. All accessions were homozygous at all loci, so "alleles" and "genotypes" were equivalent. Twenty loci were polymorphic, with two to six genotypes per locus and polymorphic indexes ranging from 0.06 to 0.74. Linkage disequilibrium was widespread. On the basis of Hedrick's probability of genotypic identity, botanical varieties T. t. ssp. eusquarrosa var. typica and T. t. ssp. eusquarrosa var. anathera were very similar to each other, as were T. t. ssp. strangulata and T. t. ssp. eusquarrosa var. meyeri, with a large genetic distance between these two pairs of taxonomic groups. Genetic variability for molecular markers was highest near the Caspian Sea, intermediate in Afghanistan, and lowest in Turkey and Pakistan. Genetic and geographical distances were related and generally consistent with the hypothesis that T. tauschii originated near the southern or southwestern coast of the Caspian Sea. Unique genotypes were found in most regions. The results of this study, along with data on economically relevant traits, will provide a basis for selecting breeding parents from the T. tauschii germ-plasm collection.Key words: germ plasm, Aegilops squarrosa, diversity, restriction fragment length polymorphism.
The Giemsa banding pattern of canine chromosomes, using a cell synchronization technique
Authors: Stone Diana M. , Jacky Peter B. , Prieur David J.
Published: April 2011

Cytogenetic investigations of the domestic dog, Canis familiaris, were performed on one Doberman pinscher and two Boxer dogs. Conventional homogeneously stained and G-banded metaphases from peripheral blood lymphocyte cultures synchronized with amethopterin and bromodeoxyuridine were studied. These procedures permitted the unequivocal identification of all canine chromosomes. A canine chromosome idiogram was constructed on the basis of the G-banding pattern at the haploid 327-band resolution level. The secondary constrictions and tapering of the telomeric regions characteristic of several canine chromosomes are described. Q-, C-, and NOR-banding were also performed and the salient features are described. This karyotype should enhance the value of the canine species in cytogenetic investigations.Key words: canine karyotype, G-banding, Q-banding, C-banding, NOR-banding, cell synchronization idiogram.
Detection of barley chromatin added to wheat by genomic in situ hybridization
Authors: Mukai Y. , Gill B. S.
Published: April 2011

A technique for in situ hybridization is reported that can be used to detect barley chromatin in wheat background using total genomic DNA as a probe. A 1:2 ratio of biotin-labeled genomic DNA of barley to blocking (unlabeled, sheared) DNA of wheat was sufficient to reveal brownish labeled barley chromosome domains against bluish background of unlabeled wheat chromatin in metaphase, prophase, and interphase nuclei of wheat-barley addition lines. Using this procedure, the behavior of specific barley chromosomes was analyzed in interphase and prophase cells. In prophase cells, the 6H chromosome was always associated with a nucleolus. A genomic clone of α-amylase gene (gRAmy56) that contains a barley-specific dispersed repeat sequence was also used to detect barley chromosomes in a wheat background.Key words: Hordeum vulgare, Triticum aestivum, genomic in situ hybridization, biotin, nucleolar organizing region.
Linkage analysis of open bud (ob2) and yellow petal (Y1) in cotton
Authors: Endrizzi J. E. , Ray D. T.
Published: April 2011

In allotetraploid Gossypium species yellow petal is controlled by duplicate dominant genes Y1 (Ah genome) and Y2 (Dh genome), and open bud is controlled by duplicate recessive genes designated ob1 (Dh genome) and ob2 (Ah genome). Y2 and ob1 have been shown previously to be linked on chromosome 18 and 11.5 map units (MU) apart. In this study ob2 and Y1 were transferred from Gossypium darwinii (Watt) accession CB3099 into Gossypium hirsutum L. and found to have a mean recombination percentage of 3.14 for backcross and 3.40 for self-pollinated families from 2n parental heterozygotes and 10.73 in families from mono-18 parental heterozygotes. The lower recombination frequency in the homoeologous linkage group was perhaps due to this chromosome segment being transferred from G. darwinii. The higher frequency of recombination in the monosomic progeny families suggests that the absence of recombination in one homoeologue (chromosome 18) is compensated for by an increase in recombination in the other homoeologue.Key words: cotton, G. hirsutum L., homoeologous linkage groups, genetic markers.
Peroxidase activity and relative mobility at anthesis in flax genotrophs and their F2 progeny: developmental and genetic effects
Authors: Fieldes M. A. , Ross J.
Published: April 2011

The genetic regulation of the environmentally induced heritable difference in peroxidase activity between Durrant's large (L) and small (S) flax genotrophs was examined in leaves from plants ranging in developmental age from 6 days before anthesis to 3 days after. Mean peroxidase activity was higher for S than L and intermediate for the reciprocal F2's from L × S and S × L crosses (F2L × S and F2S × L). However, activity increased with development and, since there were small but significant differences in the average developmental ages of L, S, F2L × S, and F2S × L plants, the effects of development on activity had to be taken into account in examining the F2 activity data for segregation. A regression method was used to remove developmental effects and, underlying these effects, total peroxidase activity appeared to be regulated by a single locus with two alleles and L dominance. Two other dimorphic loci, both described previously, were also examined. One regulates the presence-absence of septa hairs in the seed capsules and the other the relative mobility of anionic peroxidase isozymes. There was no phenotypic linkage between the three segregating parameters. The genetic control of activity appeared to regulate cationic rather than anionic activity. In addition, a relationship between activity and plant height indicated either that peroxidase activity is one of the factors regulating main stem elongation or that the locus regulating peroxidase activity is linked to one of the loci involved in the regulation of plant height.Key words: flax genotrophs, peroxidase, genetic control, development.
Genetic control of meiotic recombination in Petunia hybrida: dosage effect of gene Rm1 on segments Hf1-Lg1 and An2-Rt; role of modifiers
Authors: Robert N. , Farcy E. , Cornu A.
Published: April 2011

Populations segregating at locus Rm1 were used to measure recombination within two chromosome segments in Petunia hybrida. Gene Rm1 shows incomplete dominance and action that differs according to marker pair studied. It enhances recombination within the segment Hf1-Lg1 and restores it for the pair An2-Rt. Minor modifier genes exist, which act independent of or epistatic to Rm1 action. Like Rm1, they have effects that differ according to the chromosome segment analyzed, with the effects being more pronounced for strongly linked loci. Some of these genes are probably recessive.Key words: Petunia hybrida, gene Rm1, meiotic recombination, dosage effect.
Chromosome preparations from protoplasts: in situ hybridization banding pattern of a dispersed DNA sequence in rye (Secale cereale L.)
Authors: Jouve N. , McIntyre C. L. , Gustafson J. P.
Published: April 2011

The utilization of genome-specific DNA sequences coupled with in situ hybridization for chromosome karyotyping in wheat, rye, and triticale has been of limited value because of the presence of cellular and cytoplasmic debris. The use of protoplasts, thus eliminating cellular debris, has been shown to improve the level of detection of low-copy and unique DNA sequences in cereals. Therefore, the use of protoplasts could represent an appropriate tool to improve the results of karyotyping cereal chromosomes with genome-specific DNA sequences. This paper describes the results on the comparative application of protoplasts and squash preparations in the analysis of physical mapping of a dispersed DNA sequence (pSc119.1) to rye chromosomes by in situ hybridization. Individual chromosomes of rye were not distinguishable by their hybridization patterns to pSc119.1 when squash preparations were used. These showed an undefined distribution of the DNA probe that covered apparently the entire length of each rye chromosome. However, considerable improvement was observed for the differential distribution of the pSc119.1 DNA sequence in protoplast preparations. The karyotypic banding pattern of pSc119.1 showed a better banding pattern than can be observed using the C-banding technique. Therefore, the use of protoplasts hybridized with dispersed DNA markers could be of more value in monitoring chromosome karyotypes than existing cytological techniques.Key words: biotin labeling, dispersed sequences, rye.
A genetic map for Brassica napus based on restriction fragment length polymorphisms detected with expressed DNA sequences
Authors: Landry Benoit S. , Hubert Nathalie , Etoh Takeomi , Harada John J. , Lincoln Stephen E.
Published: April 2011

F2 segregation analyses of DNA restriction fragment length polymorphisms (RFLPs) detected between two cultivars of canola ('Westar' × Topas') was used to construct a detailed genetic map of Brassica napus. RFLP markers were from a seedling-specific cDNA library. They were either randomly selected or previously characterized as seedling-specific cDNA clones. The 120 loci so far mapped in B. napus covered 1413 recombination units. They are assembled into 19 linkage groups. Seventeen loci were found unlinked to any other markers. Few polymorphisms were detected with the seedling-specific cDNAs and only seven loci could be mapped in this cross. Duplication of RFLP loci was extensive and reflects the amphidiploid nature of this species. However, several rearrangements of the linear order of duplicated loci could be seen. This RFLP study in B. napus provides important information on genome organization of functional DNA sequences and complements our current RFLP mapping effort in Brassica oleracea. The genetic markers of this map are currently being used in several breeding applications, such as tagging important agronomic traits and fingerprinting breeding lines and cultivars of canola, a major oilseed crop.Key words: genetic mapping, Brassica napus, breeding, restriction fragment length polymorphisms.
Chromosomal fusion and meiotic behaviour in Delena cancerides (Araneae: Sparassidae). I. Chromosome pairing and X-chromosome segregation
Authors: Rowell D. M.
Published: April 2011

Surface spreading of meiotic material in Delena cancerides indicates that pairing initiation among metacentric chromosomes with monobrachial homology differs from that of telocentric forms and free metacentric bivalents and results in a star-shaped structure at pachytene. Distance cosegregation of the three X chromosomes in ancestral, telocentric forms is prefaced by a centric association early in prophase I. This centric association of the X chromosomes is conserved in metacentric races despite the presence of an X-autosome fusion.Key words: synaptonemal complex, translocation heterozygote, X chromosome, spider.
Chromosome banding in aphids: G, C, AluI, and HaeIII banding patterns in Megoura viciae (Homoptera, Aphididae)
Authors: Manicardi G. C. , Gautam D. C. , Bizzaro D. , Guicciardi E. , Pagliai A. M. Bonvicini , Bianchi U.
Published: April 2011

The holocentric mitotic chromosomes of Megoura viciae, a species that has been little studied cytogenetically to date, have been characterized by applying G, C, AluI, and HaeIII banding techniques. C bands have shown the best defined patterns, particularly on the X chromosome. This chromosome, on the other hand, behaved as the most reactive to the various treatments. Uncondensed, prometaphase X chromosomes showed a number of heterochromatic bands, interspersed among the euchromatin, which fused together during metaphase condensation. AluI and HaeIII treatments also produced reproducible banding patterns. These data permit an accurate identification of the X chromosome as well as of the autosomal pairs 1 and 2, and facilitate the construction of nonambiguous karyotypes. They will also stimulate studies on the organization of chromatin in holocentric, holokinetic chromosomes. Finally they could also promote research on chromosomal rearrangements that have occurred during the course of speciation and evolution of aphids, since these kinds of events may be significantly affected by the condition of chromosomal holocentrism.Key words: aphids, holocentric chromosomes, chromosome banding, heterochromatin.
Comparison of crossover frequencies in barley (Hordeum vulgare) and H. vulgare × H. bulbosum hybrids using a paracentric inversion
Authors: Pickering R. A.
Published: April 2011

Crosses between different parental ploidy combinations of barley (Hordeum vulgare L.) and H. bulbosum L. have been carried out principally to obtain hybrids with high allosyndetic chromosome pairing. Fertility has been observed in tetraploid and triploid hybrids, but there has been little evidence of gene introgression from H. bulbosum into H. vulgare in their progeny. To investigate whether crossing-over takes place between homoeologous chromosomes of H. vulgare and H. bulbosum, diploid hybrids were obtained from crosses between a barley mutant (wst3) homozygous for a paracentric inversion on chromosome 3 and one H. bulbosum genotype. Meiotic analyses at metaphase I and anaphase I and II were carried out on several viable hybrids and compared with control diploid hybrids without the inversion and H. vulgare plants heterozygous for the inversion. Aberrations (bridges and (or) fragments) in H. vulgare × H. bulbosum pollen mother cells at anaphase I were significantly less frequent than in the barley hétérozygote. It is concluded that reduced crossing-over between the parental chromosomes in hybrids contributes to the lack of success in obtaining genetic recombinations between the two species.Key words: Hordeum vulgare, Hordeum bulbosum, interspecific hybrid, paracentric inversion, crossing-over.
Geographic differentiation in isozyme genotypes of Himalayan barley (Hordeum vulgare)
Authors: Konishi T. , Matsuura S.
Published: April 2011

Isozyme variation among Himalayan barley (Hordeum vulgare L.) landraces was surveyed at seven loci, using 650 accessions collected from different regions. Large genetic diversities were detected at the Est1, Est2, and Est4 loci for esterase and at the Aat3 locus for aspartate aminotransferase. However, only a few variations were observed at the Pgd1 and Pgd2 loci for phosphogluconate dehydrogenase, and no variation was found at the Aat2 locus. The allelic combinations observed were not randomly distributed in the Himalayas: a geographic trend was closely related to covered and naked types of barley. The covered barleys were frequently distributed in southern regions of the Himalayas and were characterized principally by the Al-Fr-At genotype at the Est1-Est2-Est4 multilocus, combined with the Mo allele at the Aat3 locus. The naked barleys were found mainly in northern regions, and most of them possessed the genotypes Ca-Un-Nz or Pr-Fr-At, together with the Eg allele. Such a nonrandom allelic distribution provides useful information for further analysis aimed at considering the history of cultivated barley in the Himalayas.Key words: Himalayan barley, genetic diversity, isozymes, geographic distribution.
A sequence specific to B chromosomes of Brachycome dichromosomatica
Authors: John Ulrik P. , Leach Carolyn R. , Timmis Jeremy N.
Published: April 2011

Supernumerary B chromosomes represent one of many causes of numerical chromosome variation that exist in higher plants and animals. Sequences of DNA unique to B chromosomes of Brachycome dichromosomatica were enriched prior to cloning and resultant clones hybridizing only to plants containing B chromosomes were further investigated. Sequences of DNA that were characterised include members of a family of 176-bp tandem repeats that are specific to the B chromosomes of B. dichromosomatica, an annual Australian native plant species with only two pairs of A chromosomes and up to three dispensable B chromosomes. Sequence analysis of these six related clones indicated that some regions of the sequence are more highly conserved than others or, alternatively, that some adenine residues at the NdeII site are methylated. The repeat is homologous to DNA from Brachycome ciliaris var. languinosa but not to DNA from other related taxa growing in the vicinity of the B. dichromosomatica populations.Key words: plant DNA, B chromosomes, Brachycome dichromosomatica, molecular clones, repeated sequences.
No character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana
Authors: Singh B. N. , Chatterjee Sujata
Published: April 2011

To test whether character displacement for reproductive isolation between Drosophila bipectinata and Drosophila malerkotliana exists, the degree of sexual isolation was measured between their sympatric and allopatric populations. Although the isolation indices vary in different crosses, the average isolation index for sympatric populations is very close to that for allopatric populations. This shows no difference in the degree of sexual isolation between sympatric and allopatric populations of D. bipectinata and D. malerkotliana. Thus there is no evidence for the existence of character displacement for sexual isolation between these two closely related sympatric species.Key words: Drosophila bipectinata, Drosophila malerkotliana, sexual isolation, sympatric and allopatric populations.
Cytogenetical studies in Rhoeo spathacea (Commelinaceae). I. A desynaptic and second division restitution mutant
Authors: Garcia-Velazquez Armando
Published: April 2011

A mutant causing partial desynapsis (dissociation of paired chromosomes), and consequently a high frequency of univalents at metaphase 1, was found in Rhoeo spathacea among the selfed progeny of a wild-collected ring-forming complex interchange heterozygote. All the plants were diploid, 2n = 2x = 12. The mutant formed univalents in all microsporocytes (range 2–12; average 7.56/cell), and 23.69% of the pollen mother cells contained the maximum of 12 univalents at metaphase I. There was no significant difference in pollen fertility between the mutant and parental plants. The desynaptic mutant produced microspores with chromosome numbers of n = 6–14 in the same anther. Unreduced pollen was formed at telophase II by second division restitution and comprised 52.74% of the pollen grains. By selfing, diplandrogynous tetraploid progeny (2n = 4x = 24) of 12 seedlings were obtained. The results demonstrate that both male and female gametes are unreduced.Key words: Rhoeo, desynapsis, univalent, second division restitution, tetraploid.
Cytogenetics of two interspecific synthetic hybrids of the grasshopper genus Euchorthippus
Authors: Santos J. L. , Arana P. , Henriques-Gil N.
Published: April 2011

The spermatogenesis of two synthetic hybrid individuals of the grasshopper genus Euchorthippus was studied by C-banding methods. One resulted from the cross Euchorthippus pulvinatus ♂ × Euchorthippus chopardi ♀ (p/c), whereas the other one was produced in the cross E. chopardi ♂ × E. pulvinatus ♀ (c/p). The two parental sets of chromosomes were always recognized according to their different C-banding patterns. Chiasma frequency was decreased in both hybrids when compared with the parental species, this decrease being more accentuated in the hybrid individual c/p, where univalents at metaphase I were frequent. Chiasmata were formed between homoeologous chromosomes, and only two multivalent associations were observed. Polyploid spermatids and some micronuclei were a common feature in both hybrids. It is suggested that C-heterochromatin differences do not play any important role in the speciation process: genie differences between parental genomes are probably more important.Key words: synthetic hybrid, Euchorthippus, C-heterochromatin, meiotic pairing, reproductive isolating mechanisms.
Genetic variation detectable with molecular markers among unadapted germ-plasm resources of cultivated peanut and related wild species
Authors: Halward Tracy M. , Stalker H. Thomas , Larue Elizabeth A. , Kochert Gary
Published: April 2011

Peanut germ plasm consists of the cultivated allotetraploid species Arachis hypogaea L. and a large number of wild species, which are nearly all diploids. Our previous work indicated a very low level of genetic variability in American cultivars, as assayed by restriction fragment length polymorphism (RFLP) analysis. Since American cultivars might represent a narrow genetic base, we expanded our study to include unadapted germ-plasm lines from the various South American centers of origin, Africa, and China, where considerable morphological and physiological variability has been reported to exist. Wild species of section Arachis were included in the evaluations since they show a high degree of variation when assayed by RFLPs. Three methods were used to assay for RFLP variation: (i) conventional RFLP analysis using random genomic clones from peanut and cDNA clones from peanut and alfalfa (Medicago sativa); (ii) polymerase chain reaction (PCR) amplification of random primer sequences; (iii) four-cutter analysis of PCR-amplified fragments. In all cases a very low level of variability was found in cultivated peanut, while abundant variability was present among wild diploid species. The results are discussed in terms of peanut evolution and significance to peanut breeding.Key words: polymerase chain reaction, Arachis hypogaea, restriction fragment length polymorphism.
"Portraying" of plant genomes using polymerase chain reaction amplification of ribosomal 5S genes
Authors: Kolchinsky Alexander , Kolesnikova Maria , Ananiev Evgenii
Published: April 2011

Nontranscribed spacers of plant genes coding for ribosomal 5S RNA were amplified using the polymerase chain reaction. Primers were synthesized that were complementary to 3′ (direct) and 5′ (reverse) ends of the coding region and that are universal for higher plants. The patterns of polymerase chain reaction products are species and, sometimes, variety specific. The use of this approach for identification of barley 5S genes in chromosome-addition lines of wheat is discussed. This principle can be applied for the "portraying" of other tandem repetitive genes containing divergent regions.Key words: polymerase chain reaction, 5S genes, plants, DNA polymorphism.
Gene-centromere mapping in potato by half-tetrad analysis: map distances of H1, Rx, and Ry and their possible use for ascertaining the mode of 2n-pollen formation
Authors: Wagenvoort Marinus , Zimnoch-Guzowska Ewa
Published: April 2011

Diploids from the tetraploid potato varieties 'Alcmaria' and 'Pansta' and from the tetraploid CPRO genotypes Y66-13-610 and Y66-13-636 were used in half-tetrad analyses to estimate the gene-centromere map distances of the genes Rx, Ry, and H1. Employing tetraploid progeny from 2x (second division restitution) – 4x testcrosses the gene-centromere map distance of H1, conferring resistance to pathotype Ro1 of Globodera rostochiensis, was estimated to be 16.3 centimorgans (cM). For Rχ, conferring extreme resistance to potato virus X (PVX), a map distance of 33.9 cM was estimated. The gene Ry, conferring extreme resistance to potato virus Y (PVY), was estimated to be located 14.2 cM from the centromere. Using the estimated map distance for Rx, it was attempted to determine the mode of 2n-pollen formation in four diploid interspecific hybrids, including the species Solanum tuberosum, Solanum chacoense, Solanum yungasense, and Solanum phureja, by half-tetrad analysis in tetraploid progeny from 4x-2x testcrosses. The mean frequency of 8.7% nulliplex plants for Rx was outside the range of the 95% confidence intervals, for both first division restitution and second division restitution 2n pollen.Key words: nematode resistance, potato virus X resistance, potato virus Y resistance, 2n eggs, gene-centromere mapping, Solanum.
Chromosomal assignment of genes in barley using telosomic wheat–barley addition lines
Authors: Cannell Martin , Karp Angela , Isaac Peter G. , Shewry Peter
Published: April 2011

Characterized DNA clones have been used as probes in Southern blotting and hybridization analysis of genomic DNA from a set of wheat–barley telosomic addition lines to assign genes to chromosome arms in barley (Hordeum vulgare). The lines used included a newly available addition line with the short arm of chromosome 5. Addition lines with the long arm or the whole of chromosome 5 of H. vulgare are not available, so addition lines with chromosomes 5 and 5S of a related wild species, Hordeum chilense, were also used. A total of 23 characterized cDNAs and two characterized genomic clones were mapped to chromosome arms in this way.Key words: gene mapping, telosomic additions, cDNA clones, wheat-barley, restriction fragment length polymorphisms.
Chromosomal location of genes controlling lactate dehydrogenase in rye, wheat, and barley
Authors: Thiele Volker , Melz Gilbert
Published: April 2011

The chromosomal location of lactate dehydrogenease (LDH) genes in rye, barley, and wheat was investigated using the disomic standard addition sets of 'Chinese Spring' – 'Imperial' (wheat–rye) and 'Chinese Spring' – 'Betzes (wheat–barley) and the monosomic rye–wheat additions, respectively. Gel electrophoresis was performed on 5% polyacrylamide gels. Diagnostic bands for LDH isozymes were present only in zone 2. Genes controlling LDH isozymes in rye were found to be located on rye chromosome 4R (Ldh-R1and Ldh-R2) and in barley on chromosome 4Hv (Ldh-H1 and Ldh-H2). Because of the incomplete rye–wheat addition set, only one gene for LDH isozymes of wheat could be located (wheat chromosome 4B; Ldh-B1). In the three cereal species investigated, LDH genes are located generally on homoeologous group 4 chromosomes.Key words: gene location, lactate dehydrogenase, Secale cereale, Triticum aestivum, Hordeum vulgare.
The Balbiani ring and the polytene chromosomes of Drosophila bicornuta
Authors: Mavragani-Tsipidou P. , Scouras Z. G. , Natsiou-Voziki A.
Published: April 2011

A study of the BR1 and of the most prominent puffs during larval development and after in vitro ecdysterone treatment, as well as of the banding pattern and inverted tandem chromosomal duplications of the salivary gland chromosomes of Drosophila bicornuta, is presented in this report. These data are compared and discussed with those of D. auraria and D. serrata, two other montium species.Key words: Drosophila, Balbiani ring, duplications, ecdysterone.
Replicon size, rate of DNA replication, and the cell cycle in a primary hexaploid triticale and its parents
Authors: Kidd A. D. , Francis D. , Bennett M. D.
Published: April 2011

It has been previously shown that, surprisingly, DNA synthesis in a hexaploid triticale resembled that in a hexaploid bread wheat much more than in a diploid rye cultivar with respect to (i) replicon size, (ii) rate of DNA replication fork movement, and (iii) the degree of synchrony of replicon activation. The wheat and rye cultivars were not the parents of the triticale, but it was suggested that perhaps in a triticale nucleus, DNA replication in chromosomes from rye may be governed to be similar to that of wheat chromosomes in the wheat parent. The present work aimed to test this hypothesis using DNA fibre autoradiography to study DNA replication in root meristem cells of a diploid rye, a tetraploid wheat, and the primary allohexaploid triticale derived from them. The results, which again showed striking differences between rye, wheat, and triticale, did not substantiate the above-mentioned hypothesis. Instead, factors in the hybrid triticale may interact to impose a new common replicon size, a new common rate of replication, and, a more synchronous pattern of activation of replication, all different from those found in either parent. These results provide evidence for the existence of an important genetic mechanism that can act to synchronize the developmental behaviour of different ancestral diploid genomes in allopolyploids. Variation in the expression of this mechanism may have important agronomic and evolutionary consequences. Perhaps improvement in nuclear stability and in kernal type achieved in triticale breeding involves selection for greater synchrony of replicon activation during DNA synthesis.Key words: cell cycle, DNA replication, replicon, S phase, triticale.
Hordein variation in the genus Hordeum as recognized by monoclonal antibodies
Authors: Pelger Susanne , Bothmer Roland Von
Published: April 2011

The composition of the major storage protein, hordein, in wild barley species has been studied by using gel electrophoresis, Coomassie staining, and immunoblot assays. We have shown earlier that it is possible to obtain cross-reaction outside the cultivated barley, with monoclonal antibodies raised against hordeins from the barley cultivar Bomi. These antibodies have now been used to investigate the hordein composition in all species of the Hordeum genus. The results showed that polypeptides similar to the two major hordein groups of cultivated barley, the B- and C-hordeins, are produced in all wild Hordeum species, and that there are both similarities and differences between the two hordein groups. The similarities indicate a common evolutionary origin, while the distinction between B- and C-hordeins in the entire genus clearly shows that the divergence of their coding genes preceded the divergence of the Hordeum species. The presence of the same antigenic site in two different species indicates that they are evolutionarily related. Among the wild species, two rarely occurring sites were exclusively found in H. vulgare ssp. spontaneum and H. bulbosum, which confirms that they are the cultivated barley's closest relatives. Some of the antibodies also gave an extensive reaction pattern with H. murinum, which suggests a fairly close relationship to H vulgare, though not as close as between H. vulgare and H. bulbosum.Key words: Hordeum, hordein, monoclonal antibodies, evolution, multigene family.
Restriction endonuclease analysis of chloroplast DNA from streptomycin-resistant mutants of Nicotiana plumbaginifolia
Authors: To Kin-Ying , Lai Yiu-Kay , Feng Teng-Yung , Chen Chi-Chang
Published: April 2011

Chloroplast DNA isolated from wild-type Nicotiana plumbaginifolia and 12 maternally inherited streptomycin-resistant mutants was digested with various restriction enzymes and the resultant patterns were compared. No gross structural alterations of the chloroplast genome were detected in any mutants; however, variant patterns owing to the gain or loss of a restriction site were found in three mutants, SR1007, SR1019, and SR1022. The variant patterns in SR1019 and SR1022 are identical and are the results of mutation in the psbG gene coding for a chloroplast membrane protein G, and that in SR1007 is due to mutation in the 16S rRNA gene. Inheritance of the variant patterns in mutants SR1007 and SR1019 was studied. The results showed that the variant patterns and streptomycin resistance were co-transmitted in reciprocal crosses.Key words: Nicotiana plumbaginifolia, streptomycin resistance, chloroplast DNA, restriction endonuclease analysis, 16S rRNA.
Gamma irradiation induced deletions in an alien chromosome segment of the wheat 'Indis' and their use in gene mapping
Authors: Marais G. F.
Published: April 2011

Deletion mutants were produced in a translocated chromosome segment derived from Thinopyrum distichum (Thunb.) Löve. Spikes of the translocation line 'Indis' were irradiated with gamma rays at dosages of 15, 20, and 25 Gy. The irradiated spikes were pollinated with 'Inia 66' pollen and the F2 and F3 generations screened for translocation mutants, using the genes for leaf rust resistance and yellow endosperm pigmentation as markers. Finally, endopeptidase polymorphisms were utilized to select mutant translocation homozygotes within each of 29 families. An investigation of polymorphisms at the α-Amy-D2 and Wsp-D1 loci of chromosome arm 7DL revealed that 'Indis' did not produce an α-AMY-D2 product, but it did produce a novel WSP-D1 protein. The mutants were characterized for their leaf and stem rust resistances and the presence of WSP-D1 and yellow flour pigments. The stem rust resistance gene could not be accurately mapped. The linear order of the remaining loci on 7DL was centromere - leaf rust resistance - Wsp-D1 and yellow pigment. The data obtained suggested that the 'Indis' translocation has homo(eo)logy to the Lr19 translocation and homoeology to 7DL of common wheat.Key words: wheat, interspecific gene transfer, translocation, deletion mapping.
Cytological relationship between Paspalum dilatatum and diploid cytotypes of P. brunneum and P. rufum
Authors: Burson Byron L. , Quarín Camilo L.
Published: April 2011

Tetraploid Paspalum dilatatum Poir. (2n = 4x = 40, genome formula IIJJ) was crossed with diploid cytotypes of P. brunneum Mez (2n = 2x = 20) and P. rufum Nees (2n = 2x = 20), both of which have the genome formula II. The objectives of this investigation were to determine the relationship of these two diploid species to P. dilatatum and to ascertain if they are more closely related to P. dilatatum than diploid P. intermedium Munro. ex Morong, which also has the genome formula II. Crossability for both crosses was in excess of 11%, which is very high for this genus. Twelve P. dilatatum × P. brunneum and 15 P. dilatatum × P. rufum hybrids studied cytologically had 30 chromosomes. The mean meiotic chromosome associations were 14.061, 7.91 II, and 0.04 III for the P. dilatatum × P. brunneum hybrids and 15.81 I, 7.04 II, and 0.03 III for the P. dilatatum × P. rufum hybrids. These data indicate that both P. brunneum and P. rufum are related to P. dilatatum, but the I genome in P. dilatatum differs from the I genome in these species. Thus, P. intermedium is more closely related to P. dilatatum than either P. brunneum or P. rufum and remains the most probable source for the I genome in P. dilatatum.Key words: meiosis, genomes, interspecific hybrids, chromosome pairing, dallisgrass.
Structure of the 5S rRNA genes in birch (Betula papyrifera) and alder (Alnus incana)
Authors: Johnson D. A. , Chan C. C-Y. , Gottlob-McHugh S. G. , Mackenzie K. , Marengère L. , Prud'homme M. C.
Published: April 2011

Hybridization of a 5S rDNA probe to Southern transfers of birch (Betula papyrifera) or alder (Alnus incana) DNA digested with BamH1 reveals similar triple-band "ladder-like" patterns. The sizes of sequenced 5S repeat units from both plants ranges only from 471 to 490 base pairs, suggesting that the complexity detected by Southern analysis is not due to different size classes of 5S repeats as found in other species. Within the intercistronic spacer region, conservation of large blocks of sequence between birch and alder 5S is observed implying a close evolutionary relationship between these two species. In both species, a duplication of part of the coding sequence including a restriction site for BamH1 introduces a second BamH1 site into the repeat unit. Differential methylation of the two BamH1 restriction sites can account for the observed triple-band pattern.Key words: 5S rDNA repeat, sequence, methylation, birch, alder.
Mitotic and polytene chromosome analysis in Dacus oleae (Diptera: Tephritidae)
Authors: Mavragani-Tsipidou P. , Karamanlidou G. , Zacharopoulou A. , Koliais S. , Kastritsis C.
Published: April 2011

The present study constitutes the first attempt to construct a photographic map of the polytene chromosomes of Dacus oleae, a pest of the olive tree that causes serious financial damage in all olive oil producing countries. The map was constructed by using the larval fat body cells, the chromosomes of which are representative of the polytene chromosomes of other polytene tissues. In addition, the mitotic chromosomes of brain ganglia were examined, permitting tentative correlations between mitotic and polytene elements. This investigation shows that D. oleae is suitable for cytogenetic analysis in both mitotic and polytene chromosomes, a fact that may prove very useful for obtaining more detailed genetic information on the pest's natural populations.Key words: Dacus oleae, polytene chromosomes, mitotic chromosomes.
New equations and a method for finding nine parameter values for two alleles at one locus to study gene conversion using Ascobolus immersus
Authors: Lamb B. C. , Zwolinski S. A.
Published: April 2011

A quantitative treatment is given for meiotic gene conversion with its parameters and equations for their interactions to determine allele segregation class frequencies from heterozygotes. The possible pairing of both pairs of nonsister chromatids in a bivalent at exactly the same point is included. Using sets of data from Ascobolus immersus, it is shown that values for all nine parameters for hybrid DNA models of recombination can be obtained using an iterative computer program. The accuracy of the values is estimated and the double-strand gap repair model is considered. The parameter values obtained invalidate most of the simplifications used in previous quantitative analyses of gene conversion data. They showed total bias in strand preference in asymmetric hybrid DNA formation and some bias in which type of chromatid is the invading one. There were slight differences in repair frequency between the two types of mispair and very large differences in the direction of repair. Conversion control factors had major effects on hybrid DNA formation and repair of mispairs.Key words: Ascobolus, gene conversion, quantitative analysis, recombination mechanisms.