bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic and biochemical analysis of glutathione-S-transferase in the oxygen defense system of Drosophila melanogaster
Authors: Parkes Tony L. , Hilliker Arthur J. , Phillips John P.
Published: May 2008

Aerobic organisms possess an array of enzymatic defense mechanisms against the toxic effects of active oxygen species. These include CuZn superoxide dismutase (CuZn SOD), catalase (CAT), and glutathione peroxidase (GPOX). Insects, however, lack an independent GPOX enzyme and instead rely on the activity of the more general detoxification enzyme, glutathione-S-transferase (GST), to carry out a peroxidase function. We report here the developmental profile of GST in Drosophila melanogaster and show that GST is induced by paraquat, a known free-radical generating agent. We also report that glutathione (GSH) depletion induced by administration of buthionine sulfoximine (BSO) selectively reduces the viability of mutants lacking CuZnSOD. By measuring GST specific activity in flies carrying deficiencies for the 87B region, we confirm an earlier report that this region contains active GST-encoding genes. Finally, through a biochemical analysis of representative alleles of known lethal complementation groups in this region, we have identified ck17 as a putative GST subunit gene. The implications of these findings to the role of GSH and GST in D. melanogaster oxygen defense are discussed.Key words: glutathione-S-transferase, paraquat, CuZn superoxide dismutase, oxygen defense.
Variability and evolution of highly repeated DNA sequences in the genus Beta
Authors: Schmidt T. , Heslop-Harrison J. S.
Published: May 2008

Satellite DNA from wild beet species was separated from restriction endonuclease digested genomic DNA by polyacrylamide gel electrophoresis. Two nonhomologous HaeIII satellite DNA repeats were cloned from the wild beet Beta trigyna. The type I repeat is 140–149 bp long and AT rich, while the type II is 162 bp in size and GC rich. A third repetitive HaeIII element cloned from the related wild beet B. corolliflora was shown to be organized as a HinfI satellite DNA family in the cultivated beet B. vulgaris ssp. vulgaris and the wild beet B. vulgaris ssp. maritima. This type III satellite monomer is 149 bp long and contains a high number of short direct subrepeats. The monomer was found in different genomic organizations and copy numbers in all sections of the genus Beta indicating an amplification early in the phylogeny. The HaeIII repeats from B. trigyna are characterized by a lower variability and form long tandem arrays in the genomes of Corollinae species. The investigation of the distribution of all three sequence families provided data that may contribute to the solution of taxonomic problems of the genus Beta and be useful in the characterization of hybrids and derived lines with alien wild beet chromosomes.Key words: satellite DNA, Beta vulgaris, Beta corolliflora, Beta trigyna, evolution, repetitive DNA.
Rapid detection of 1B, 1BL/1RS heterozygotes in the development of homozygous 1BL/1RS translocation stocks of Triticum turgidum (2n = 4x = 28)
Authors: William M. D. H. M. , Mujeeb-Kazi Abdul
Published: May 2008

A biochemical marker was utilized to facilitate detection of chromosome 1B, 1BL/1RS translocation heterozygote plants in segregating backcross progenies during the development of 1BL/1RS homozygous lines in several Triticum turgidum L. cultivars (2n = 4x = 28; AABB). Isoelectric focussing of glucose phosphate isomerase (GPI) on either pH 3.5–9.5 or 5.5–8.5 polyacrylamide gels facilitated the detection of 1B, 1BL/1RS translocation heterozygotes from the homozygous 1B or 1BL/1RS derivatives during each backcross of the heterozygote to the respective recurrent parent. The biochemical diagnostic procedure complements the more time consuming and cumbersome chromosome banding technique. This GPI diagnostic in durum 1BL/1RS development is also swifter than a similar stocks development in T. aestivum where both GPI and acid PAGE are essential.Key words: Triticum turgidum, glucose phosphate isomerase, 1BL/1RS translocation, isoelectric focusing.
Identification, characterization, and analysis of cDNA and genomic sequences encoding two different small heat shock proteins in Hordeum vulgare
Authors: Marmiroli Nelson , Pavesi Angelo , Cola Gabriella Di , Hartings Hans , Raho Giovanna , Conte Maria Rosaria , Perrotta Carla
Published: May 2008

In vitro translation of mRNAs prepared from barley (Hordeum vulgare) seedlings (cv. Onice) exposed at 40 °C directed the synthesis of major heat shock proteins (HSPs) with molecular masses of 80–90, 70, 42 and 16–22 kDa. A cDNA library prepared from the 40 °C mRNAs and screened by differential hybridization led to the isolation of heat shock specific sequences. One of these (Hv hsp18) was confirmed by hybrid-arrested and hybrid-released translation as encoding for an 18-kDa HSP. The barley hsp18 sequence has an open reading frame encoding a 160 amino acid residue 18-kDa protein that is 63% identical to wheat 16.9-kDa HSP (clone C5-8), 54% identical to soybean (Glycine max) 17.5-kDa HSP, and 49% identical to Arabidopsis thaliana 17.6-kDa HSP. Lower similarities were found with class II plant small HSPs such as soybean 17.9-kDa HSP (27%), Pisum sativum 17.7-kDa HSP (30%), wheat (Triticum aestivum) 17.3-kDa HSP (clone Ta hsp 17.3) (30%), and with animal small HSPs and α-crystallins. The Hv hsp18 sequence was used to pick up Hv hsp17 genomic sequence encoding for another class I 17-kDa HSP. By computer analysis of the nucleotide sequence the TATA box, two heat shock promoter elements, a metal-ion response element, and the polyadenylation signals were identified. Barley HSP 18 has an additional cysteine-rich region when compared with HSP17 mapping at the carboxy terminal end.Key words: barley, cDNA, genomic clone, heat shock, nucleotide sequence, small heat shock proteins.
Synaptonemal complex analysis in spermatocytes of tilapia, Oreochromis niloticus (Pisces, Cichlidae)
Authors: Foresti Fausto , Oliveira Claudio , Galetti Junior Pedro Manoel , Almeida-Toledo Lurdes Foresti de
Published: May 2008

Some adaptations of the synaptonemal complex (SC) whole-mounting technique first used in plants permitted its application to meiotic studies in tilapia, Oreochromis niloticus. Direct observation of the chromosome pairing process and bivalent structure during the meiotic prophase of this fish species by light and electron microscopy permitted the analysis of SCs in autosomes and the possible identification of sex chromosomes. The analysis of SCs in spermatocytes of O. niloticus revealed that all 22 bivalent chromosomes completely paired, except for the occurrence of a size heteromorphism in the terminal region of the largest bivalent associated with the presence of an incompletely paired segment during the synapsis process, which may be the cytological visualization of an XX/XY sex chromosome system in this species.Key words: fish cytogenetics, synaptonemal complex, fish meiosis, sex chromosomes, nucleolus organizer regions.
C-banded karyotypes and polymorphisms in hexaploid oat accessions (Avena spp.) using Wright's stain
Authors: Jellen E. N. , Phillips R. L. , Rines H. W.
Published: May 2008

A chromosome C-banding protocol using Wright's stain was employed to compare chromosomes in cultivars and wild accessions of several hexaploid oat taxa (Avena spp.). This technique permits the identification of each of the 21 somatic hexaploid oat chromosomes. Digital images of C-banded cells were captured on computer and used to construct karyotypes of several oat accessions. Polymorphisms for C-bands among oat cultivars and wild accessions are described. These banding polymorphisms can be used to trace introgression of chromosomes from wild sources and to provide physical markers on the genetic map for oat. Although C-banding permits the identification of likely C-genome chromosomes based on comparisons with C-banding patterns in diploid and tetraploid Avena species, the A and D genomes cannot be readily differentiated based on their banding patterns.Key words: Avena, C-banding, oat, image analysis.
Mutational divergence of life-history traits in an obligate parthenogen
Authors: Toline C. Anna , Lynch Michael
Published: May 2008

Three lines of obligately parthenogenetic Daphnia were allowed to diverge for a 4-year period (approximately 150 generations) with mutation as the sole source of variability. Life-history traits and morphological characters were then surveyed for between-line differences. Significant divergence was found with respect to both number and size of offspring, with no difference in total offspring biomass. No significant differences were found in any of the other characters. These results confirm the hypothesis that purely asexual lines can accumulate enough polygenic variation via mutation to support potentially adaptive changes on a microevolutionary time scale.Key words: Daphnia, life-history trait, mutational divergence, microevolution.
Synaptic anomalies in fetal bovine oocytes
Authors: Koykul W. , Basrur P. K.
Published: May 2008

Chromosome pairing abnormalities in oocytes of bovine fetuses ranging in age from 81 to 130 days were studied using the surface-spread whole-mount technique. The synaptic abnormalities included partial or total asynapsis, nonhomologous pairing, and mid-pachytene degeneration with asynapsis constituting the most common category. Oocytes showing synaptic abnormalities were less frequent in younger fetuses and more abundant in fetuses older than 110 days. Histologic signs of oocyte degeneration, evident in all fetuses, were most striking in ovaries of fetuses older than 120 days. The temporal relationship of these events suggests that chromosome pairing anomalies may be associated with oocyte degeneration, although their exact role in precipitating oocyte atresia remains unclear. The presence of abnormal oocytes and follicles in the vicinity of the medullary cords seems to suggest that these germ cells may be exposed to deleterious substances from the degenerating rete cords and that the synaptic errors may be the meiotic manifestations of chromosome damages sustained by germ cells during the repeated oogonial divisions in an environment unconducive to mitosis and maturation of female germ cells.Key words: synaptonemal complex, cattle, female meiosis, oocyte degeneration.
Novel variants of the 5S rRNA genes in Eruca sativa
Authors: Singh Kapil , Bhatia Sabhyata , Lakshmikumaran Malathi
Published: May 2008

The 5S ribosomal RNA (rRNA) genes of Eruca sativa were cloned and characterized. They are organized into clusters of tandemly repeated units. Each repeat unit consists of a 119-bp coding region followed by a noncoding spacer region that separates it from the coding region of the next repeat unit. Our study reports novel gene variants of the 5S rRNA genes in plants. Two families of the 5S rDNA, the 0.5-kb size family and the l-kb size family, coexist in the E. sativa genome. The 0.5-kb size family consists of the 5S rRNA genes (S4) that have coding regions similar to those of other reported plant 5S rDNA sequences, whereas the 1-kb size family consists of the 5S rRNA gene variants (S1) that exist as 1-kb BamHI tandem repeats. S1 is made up of two variant units (V1 and V2) of 5S rDNA where the BamHI site between the two units is mutated. Sequence heterogeneity among S4, V1, and V2 units exists throughout the sequence and is not limited to the noncoding spacer region only. The coding regions of V1 and V2 show approximately 20% dissimilarity to the coding regions of S4 and other reported plant 5S rDNA sequences. Such a large variation in the coding regions of the 5S rDNA units within the same plant species has been observed for the first time. Restriction site variation is observed between the two size classes of 5S rDNA in E. sativa. The noncoding spacers of the variants V1 and V2 that make up the 1-kb family lack the EcoRI site that is present in the 0.5-kb family. The sequence analysis indicates that V1 and V2 sequences are probably pseudogenes derived from functional 5S rRNA genes. The results also suggest that the two families exist as independent clusters at different locations in the E. sativa genome.Key words: 5S rRNA genes, crucifers, Eruca sativa, organization, sequence analysis.
Mapping of abscisic acid responsive genes and vp1 to chromosomes in wheat and Lophopyrum elongatum
Authors: Cadle M. M. , Rayfuse L. M. , Walker-Simmons M. K. , Jones S. S.
Published: May 2008

The plant hormone abscisic acid (ABA) affects developmental and physiological processes that can impact crop production. These processes include germination, environmental stress responses in vegetative tissue, embryo maturation, and dormancy. Identification and molecular tagging of ABA-responsive genes, as well as the vp1 gene, required for ABA sensitivity, may be valuable in developing breeding strategies designed for manipulating ABA-regulated traits. Using aneuploid genetic stocks and alien substitution lines the chromosomal location of vp1 and seven abscisic acid (ABA) responsive genes was determined in wheat and Lophopyrum elongatum (Host) Löve. Clones (gene homology, if known, in parentheses) isolated from wheat hybridized to wheat and L. elongatum homoeologous chromosome groups as follows: pMA80 (dhn), chromosome 4; pMA1949 (group 3 LEA (1I)), chromosome 3S; pMA1951, chromosome 5S; pMA1959 (Em), chromosome 1L; pMA2005 (group 3 LEA), chromosome 1S; and PKABA1, chromosome 2L. Clone pBS128, corresponding to an ABA-responsive gene from Bromus secalinus, hybridized to wheat chromosome 2S. The cDNA clone pcvp23 that is homologous to vp1, a gene required for ABA responsiveness and the prevention of precocious germination in maize embryos, did not hybridize well with wheat but hybridized to chromosomes 3L and 7β in L. elongatum. Three of the clones mapped previously in barley by other researchers, pMA1949, pMA1951, pMA1959, were found here to be on the corresponding homoeologous chromosomes in wheat.Key words: abscisic acid, Triticum aestivum, Lophopyrum elongatum, homeology, mapping.
Polymorphism in the coding sequence of the horse transferrin gene
Authors: Carpenter Margaret A. , Broad Tom E.
Published: May 2008

Transferrin, the iron transport protein of the blood, is highly polymorphic in many species, including the horse. A number of sequence polymorphisms that distinguish several of the variants of horse transferrin are reported here. Previous studies indicated that exons 12 and 15 were likely to be polymorphic. Sequencing regions of exons 12 and 15 from D and R variants revealed 10 nucleotide substitutions that encoded six amino acid replacements. The F1, F2, H2, and * variants were identical to D, and the O variant was almost identical to R, in the regions studied. The data indicated that the horse transferrin variants make up two distinct groups. The positions of differences between the D and F1 alleles were determined by analyzing single-stranded conformation polymorphisms. Sequencing then revealed three nucleotide substitutions, two of which encoded amino acid substitutions. Location of the eight polymorphic residues on the three-dimensional structure of human lactoferrin revealed that all were clustered at one end of the C-lobe.Key words: sequence polymorphism, transferrin, horse, nucleotide substitution, allele.
Haploid regeneration from tetraploid wheat using maize pollen
Authors: Sarrafi A. , Amrani N. , Alibert G.
Published: May 2008

Crosses were made between 21 tetraploid wheat genotypes (6 parents, 15 F1 hybrids) and a single F1 hybrid of maize that was used as the male parent. Plants were grown under controlled greenhouse conditions (daylength, 16 h; temperature, 25 °C days and 15 °C nights). To enhance embryo survival, 2,4-D (10 mg/L) was applied to spikes 24 h after pollination with maize. Embryos were recovered from the tetraploid wheat genotypes at a rate of 2.34–14.14/100 developed ovaries. Sixty-nine haploid plants were obtained from 3 parents and 12 F1, hybrids. Fifty-six of these were successfully doubled. General combining ability was significant for the two traits studied, indicating that additive genetic control is important for the number of developed ovaries and haploid embryo production in tetraploid wheat × maize crosses. In this report, we demonstrate the potential of using maize pollen to produce haploid plants from tetraploid wheat genotypes.Key words: tetraploid wheat, embryo culture, haploid, wheat × maize, combining abilities.
Meiosis in triploid Lolium. I. Synaptonemal complex formation and chromosome configurations at metaphase I in aneuploid autotriploid L. multiflorum
Authors: Thomas Huw M. , Thomas Barry J.
Published: May 2008

A spreading technique for synaptonemal complexes (SCs) was applied to pollen mother cells of two aneuploid genotypes of autotriploid Lolium multiflorum (2n = 3x + 1 = 22). In the earliest nuclei analyzed the axial elements are in six groups of 3 and one group of 4. Most groups have formed multivalents with from one to five pairing partner exchanges, but there are also groups that have formed bivalents and univalents. Some axial elements have formed triple associations, in one case for the length of the trivalent. Unsynapsed axial elements remain aligned with their homologous SCs into pachytene, but this alignment is abolished as these axes pair heterologously among themselves until the entire axial element complement is synapsed. At metaphase I most chromosomes are associated as trivalents and quadrivalents.Key words: Lolium, triploid, pairing partner exchange, chiasma, multivalent.
The raspberry locus of Drosophila melanogaster includes an inosine monophosphate dehydrogenase like coding sequence
Authors: Nash D. , Hu S. , Leonard N.-J. , Tiong S. Y. K. , Fillips D.
Published: May 2008

DNA from the raspberry gene of Drosophila melanogaster has been cloned through P-element tagging of a dysgenically induced lethal allele. A transcribed DNA segment adjacent to the P insert encodes an amino acid sequence that is similar to known inosine monophosphate dehydrogenase (IMPDH) sequences. Further dysgenically induced lethals and all four known spontaneous ras eye-colour mutations have changes in the DNA either within or just upstream from the transcribed region. Identification of IMPDH as a probable product of the ras gene is compatible with the finding of an allele that requires dietary guanosine (GR), since the enzyme mediates the first of two biosynthetic steps leading from inosine monophosphate (IMP) to guanosine monophosphate (GMP). However, other auxotrophic mutants at the locus remain unexplained by the finding. The results further suggest that GMP synthesis from IMP is an essential process, despite the capacity of the fly for salvage synthesis of GMP from GR. Consideration of the phenotypes associated with mutants at the ras locus suggests that IMPDH activity is regulated in a tissue-specific manner.Key words: inosinate dehydrogenase, IMPDH, guanosine auxotrophy, purine synthesis, raspberry mutants, lethal mutations, Drosophila melanogaster.
Sequence conservation of an avian centromeric repeated DNA component
Authors: Madsen Cort S. , Brooks Jeannette E. , Kloet Edwin de , Kloet Siwo R. de
Published: May 2008

The approximately 190-bp centromeric repeat monomers of the spur-winged lapwing (Vanellus spinosus, Charadriidae), the Chilean flamingo (Phoenicopterus chilensis, Phoenicopteridae), the sarus crane (Grus antigone, Gruidae), parrots (Psittacidae), waterfowl (Anatidae), and the merlin (Falco columbarius, Falconidae) contain elements that are interspecifically highly variable, as well as elements (trinucleotides and higher order oligonucleotides) that are highy conserved in sequence and relative location within the repeat. Such conservation suggests that the centromeric repeats of these avian species have evolved from a common ancestral sequence that may date from very early stages of avian radiation.Key words: satellite DNA, centromeric repeat, avian, sequence conservation.
Assignment of a gene that determines erythrocytic guanosine-5′-triphosphate concentration (Gtpc) to mouse chromosome 9
Authors: Jenuth Jack P. , Fung Ernest , Snyder Floyd F.
Published: May 2008

Nine inbred mouse strains surveyed for erythrocytic guanosine-5′-triphosphate (GTP) concentration were found to segregate into two discrete groups. Strains having low GTP levels between 1.4 and 3.4 nmol/109 cells were C3H/HeJ, C3H/HeHa, A/J, and WB/ReJ. Strains having high GTP levels between 11.0 and 14.8 nmol/109 cells were AKR/J, DBA/2J, CBA/J, C57BL/6J, and C57L/J. Erythrocytic ATP levels did not vary significantly among these groups. Crosses between low and high GTP strains gave F1 progeny having intermediate levels of GTP, and the progeny of F1's backcrossed to parental strains segregated in a 1:1 ratio for GTP concentration. We designated the GTP concentration determining trait, Gtpc. Typing the C57BL/6J × C3H/HeJ (B × H) recombinant inbred strains for GTP levels revealed 0/12 strain distribution pattern differences for loci on both chromosomes 5 and 9. Backcross analysis did not provide evidence for linkage of Gtpc to W (dominant white spotting) on chromosome 5 with 15/45 recombinants. A test for linkage of Gtpc to transferrin (Trf) on chromosome 9 gave evidence of linkage with an observed recombination frequency of 14.6 ± 5.5 and a 99% confidence interval of 3.9–33.9 cM.Key words: guanosine-5′-triphosphate, GTP, mouse, chromosome 9.
Genetic studies of leaf and stem rust resistance in six accessions of Triticum turgidum var. dicoccoides
Authors: Bai Dapeng , Knott D. R.
Published: May 2008

Six accessions of Triticum turgidum var. dicoccoides L. (4x, AABB) of diverse origin were tested with 10 races of leaf rust (Puccinia recondita f.sp. tritici Rob. ex Desm.) and 10 races of stem rust (P. graminis f.sp. tritici Eriks. &Henn.). Their infection type patterns were all different from those of lines carrying the Lr or Sr genes on the A or B genome chromosomes with the same races. The unique reaction patterns are probably controlled by genes for leaf rust or stem rust resistance that have not been previously identified. The six dicoccoides accessions were crossed with leaf rust susceptible RL6089 durum wheat and stem rust susceptible 'Kubanka' durum wheat to determine the inheritance of resistance. They were also crossed in diallel to see whether they carried common genes. Seedlings of F1, F2, and BC1F2 generations from the crosses of the dicoccoides accessions with RL6089 were tested with leaf rust race 15 and those from the crosses with 'Kubanka' were tested with stem rust race 15B-1. The F2 populations from the diallel crosses were tested with both races. The data from the crosses with the susceptible durum wheats showed that resistance to leaf rust race 15 and stem rust race 15B-1 in each of the six dicoccoides accessions is conferred by a single dominant or partially dominant gene. In the diallel crosses, the dominance of resistance appeared to be affected by different genetic backgrounds. With one exception, the accessions carry different resistance genes: CI7181 and PI 197483 carry a common gene for resistance to leaf rust race 15. Thus, wild emmer wheat has considerable genetic diversity for rust resistance and is a promising source of new rust resistance genes for cultivated wheats.Key words: wheat rust, leaf rust, stem rust, rust resistance, genetic diversity.
Transfer of leaf rust and stem rust resistance genes from Triticum triaristatum to durum and bread wheats and their molecular cytogenetic localization
Authors: Bai D. , Scoles G. J. , Knott D. R.
Published: May 2008

Six accessions of Triticum triaristatum (Willd) Godr. &Gren. (syn. Aegilops triaristata) (6x, UUMMUnUn), having good resistance to both leaf rust (Puccinia recondita f.sp. tritici Rob. ex Desm) races and stem rust (P. graminis f.sp. tritici Eriks. &Henn.) races, were successfully crossed with both susceptible durum wheats (T. turgidum var. durum L., 2n = 28, AABB) and bread wheats (T. aestivum, 2n = 42, AABBDD). In some crosses, embryo rescue was necessary. The T. triaristatum resistance was expressed in all F1 hybrids. Backcrossing of the F1 hybrids to their wheat parents to produce BC1F1 plants was more difficult (seed set 0–7.14%) than to produce F1 hybrids (seed set 12.50–78.33%). The low female fertility of the F1 hybrids was due to low chromosome pairing. Only gametes with complete or nearly complete genomes from the F1 hybrids were viable. In BC2F4 populations from the cross MP/Ata2//2*MP, monosomic or disomic addition lines (2n = 21 II + 1 I or 22 II) with resistance to leaf rust race 15 (IT 1) were selected. In BC2F2 populations from the crosses CS/Ata4//2*MP and MP/Ata4//2*MP, monosomic or disomic addition lines with resistance to either leaf rust race 15 or stem rust race 15B-1 (both IT 1) were selected. Rust tests and cytology on the progeny of the disomic addition lines confirmed that the genes for rust resistance were located on the added T. triaristatum chromosomes. The homoeologous groups of the T. triaristatum chromosomes in the addition lines from the crosses MP/Ata2//2*MP, CS/Ata4//2*MP, and MP/Ata4//2*MP were determined to be 5, 2, and 7, respectively, through the detecting of RFLPs among genomes using a set of homoeologous group specific wheat cDNA probes. The addition lines with resistance to leaf rust race 15 from the crosses MP/Ata2//2*MP and CS/Ata4//2*MP were resistant to another nine races of leaf rust and the addition line with resistance to stem rust race 15B-1 from the cross MP/Ata4//2*MP was resistant to another nine races of stem rust as were their T. triaristatum parents. Since such genes provide resistance against a wide spectrum of rust races they should be very valuable in wheat breeding for rust resistance.Key words: Triticum triaristatum, rust resistance, addition line, molecular cytogenetics.
Sex chromosome pairing and sex chromatin bodies in W–Z translocation strains of Ephestia kuehniella (Lepidoptera)
Authors: Marec František , Traut Walther
Published: May 2008

Structure and pairing behavior of sex chromosomes in females of four T(W;Z) lines of the Mediterranean flour moth, Ephestia kuehniella, were investigated using light and electron microscopic techniques and compared with the wild type. In light microscopic preparations of pachytene oocytes of wild-type females, the WZ bivalent stands out by its heterochromatic W chromosome strand. In T(W;Z) females, the part of the Z chromosome that was translated onto the W chromosome was demonstrated as a distal segment of the neo-W chromosome, displaying a characteristic non-W chromosomal chromomere–interchromomere pattern. This segment is homologously paired with the corresponding part of a complete Z chromosome. In contrast with the single ball of heterochromatic W chromatin in highly polyploid somatic nuclei of wild-type females, the translocation causes the formation of deformed or fragmented W chromatin bodies, probably owing to opposing tendencies of the Z and W chromosomal parts of the neo-W. In electron microscopic preparations of microspread nuclei, sex chromosome bivalents were identified by the remnants of electron-dense heterochromatin tangles decorating the W chromosome axis, by the different lengths of the Z and W chromosome axes, and by incomplete pairing. No heterochromatin tangles were attached to the translocated segment of the Z chromosome at one end of the neo-W chromosome. Because of the homologous pairing between the translocation and the structurally normal Z chromosome, pairing affinity of sex chromosomes in T(W;Z) females is significantly improved. Specific differences observed among T(W;Z)1–4 translocations are probably due to the different lengths of the translocated segments.Key words: Mediterranean flour moth, sex chromosomes, sex chromatin, translocations, synaptonemal complexes, microspreading.
Seed storage protein variation in Arachis species
Authors: Lanham P. G. , Forster B. P. , McNicol P. , Moss J. P. , Powell W.
Published: May 2008

Seventy-two accessions, representing 22 species from sections Arachis, Erectoides, Extranervosae, and Triseminalae of the genus Arachis, were screened for seed storage protein polymorphism. Variation was detected between sections, between genome types, between species, and in some cases between different accessions of the same species or different seeds of the same accession. Arachis duranensis and one accession of A. cardenasii were found to have identical protein patterns. The greatest dissimilarity was found between species of the section Extranervosae and species of the section Triseminalae. Those of section Erectoides showed much similarity with some species of section Arachis. Protein polymorphism was shown to distinguish the two subspecies of A. hypogaea (fastigiata and hypogaea) in 27 of 28 cases. The seed protein profile of A. monticola was a combination of seed protein profiles from the two A. hypogaea subspecies. The relatedness between the various species was calculated and those that had the greatest similarity with A. hypogaea were A. spegazzinii and A. batizocoi.Key words: Arachis, groundnut, storage proteins, variation.
Identification of a sequence motif upstream of the Drosophila Dopa decarboxylase gene that enhances heterologous gene expression
Authors: Hodgetts Ross B. , Patel Millan S. , Piorecky Jana , Swan Andrew D. , Spencer Charlotte A.
Published: May 2008

In this paper we have examined the role that element S, a DNA sequence motif found approximately 215 bp upstream of the Dopa decarboxylase (Ddc) gene, might play in regulating Ddc expression. Nearly identical versions of the element are present upstream of four other Drosophila genes. For two of these, the element appears to be an important component of the upstream regulatory region, since mutations in it reduce expression of the downstream gene. Because an element S polymorphism differentiates the Ddc+ allele of an inbred laboratory strain from the Ddc+4 allele present in a strain isolated from the wild, we decided to test the activity of both forms. Oligonucleotides containing Ddc+ or Ddc+4 versions of element S were synthesized and their ability to drive the expression of an heterologous (Adh) reporter gene at the second molt was examined. Transgenic larvae carrying the element S – Adh fusion constructs consistently exhibited Adh levels that were elevated 1.5-fold above those seen in control organisms. We have also determined the effects of element S in white prepupae and once again, ADH expression levels were significantly above controls in both groups of transformants carrying the element S construct. The results point to a functional role for element S. Since reporter gene expression in third instar larvae was restricted to tissues where ADH is normally found, we conclude that element S is not involved in directing the tissue specificity of Ddc expression. However, its ability to enhance heterologous gene expression suggests that it may be the fifth in the set of cis-acting sequences in the complex regulatory domain known to specify epidermal Ddc expression during development.Key words: Drosophila, Dopa decarboxylase, regulatory element, reporter gene, transgenic flies.
Meiotic studies on a Brassica campestris–alboglabra monosomic addition line and derived B. campestris primary trisomics
Authors: Cheng B. F. , Heneen W. K. , Chen B. Y.
Published: May 2008

Diakinesis chromosomes were studied in pollen mother cells of Brassica campestris (2n = 20, genome AA), B. alboglabra (2n = 18, genome CC), a B. campestris–alboglabra monosomic addition line (AA + 1 chromosome from the C genome), and four derived B. campestris primary trisomics. The nucleolar chromosomes of B. campestris were distinguishable by their morphology at diakinesis. The alien C-genome chromosome in the addition line paired preferentially with the nucleolar chromosome of the A genome. Very rarely, it paired with another pair of the A genome. Thus, it was concluded that the alien C-genome chromosome of the addition line is primarily homoeologous to the nucleolar chromosome and secondarily to another chromosome of the A genome. Three of the four derived B. campestris trisomic plants were identified as B campestris nucleolar trisomics. Trisomy in the fourth plant involved another chromosome. The cytological mechanism underlying the origin of trisomics in the addition line and chromosome homoeology relationships between B. campestris and B. alboglabra are envisaged.Key words: Brassica campestris–alboglabra addition line, Brassica campestris trisomics, diakinesis, intergenomic chromosome homoeology.
Genomic in situ hybridization differentiates between A/D- and C-genome chromatin and detects intergenomic translocations in polyploid oat species (genus Avena)
Authors: Jellen E. N. , Gill B. S. , Cox T. S.
Published: May 2008

The genomic in situ hybridization (GISH) technique was used to discriminate between chromosomes of the C genome and those of the A and A/D genomes in allopolyploid oat species (genus Avena). Total biotinylated DNA from A. strigosa (2n = 2x = 14, AsAs genome) was mixed with sheared, unlabelled total DNA from A. eriantha (2n = 2x = 14, CpCp) at a ratio of 1:200 (labelled to unlabelled). The resulting hybridization pattern consisted of 28 mostly labelled and 14 mostly unlabelled chromosomes in the hexaploids. Attempts to discriminate between chromosomes of the A and D genomes in A. sativa (2n = 6x = 42, AACCDD) were unsuccessful using GISH. At least eight intergenomic translocation segments were detected in A. sativa 'Ogle', several of which were not observed in A. byzantina 'Kanota' (2n = 6x = 42, AACCDD) or in A. sterilis CW 439-2 (2n = 6x = 42, AACCDD). At least five intergenomic translocation segments were observed in A. maroccana CI 8330 'Magna' (2n = 4x = 28, AACC). In both 'Ogle' and 'Magna', positions of most of these translocations matched with C-banding patterns.Key words: Avena sativa, oat, in situ hybridization, C-banding, Avena macrostachya.
Cytological and electrophoretic analysis of DNA methylation in the holocentric chromosomes of Megoura viciae (Homoptera, Aphididae)
Authors: Manicardi G. C. , Bizzaro D. , Azzoni P. , Bianchi U.
Published: May 2008

Chromosomal and purified DNA methylation patterns were determined in the holocentric chromosomes of Megoura viciae by treatment with MspI and HpaII. Both enzymes produced a clear C-like banding pattern but widely digested one telomere of the X chromosome, which appeared as heterochromatic after C-banding treatment and brightly fluorescent after chromomycin A3 staining. Quantitative microfluorometric evaluations of DNA extraction performed on cytological preparations showed that both isoschizomers resulted in the same DNA extraction (about 30%). Contrary to what was found by in situ endonuclease treatment, the electrophoretic patterns of purified and digested DNA showed that digestion with MspI was slightly more extensive than that with HpaII in a zone of fragments ranging from 23 to 9 kb. This result indicates that aphid chromatin is not wholly unmethylated. The discrepancy between electrophoretic and cytological data has been explained by taking into consideration that DNA fragments with high molecular weights could be cleaved in situ by the enzymes but not extracted from the chromatin.Key words: aphids, DNA methylation, holocentric chromosomes, heterochromatin, restriction enzyme bandings.
Undertransmission of a supernumerary chromosome segment through heterozygous females possessing B chromosomes in the grasshopper Eyprepocnemis plorans
Authors: López-León M. D. , Pardo M. C. , Cabrero J. , Camacho J. P. M.
Published: May 2008

The transmission ratio (ks) for a supernumerary chromosome segment was studied in a total of 54 heterozygous females collected from two Spanish natural populations of the grasshopper Eyprepocnemis plorans. Our analysis clearly demonstrated that ks is negatively dependent on the number of B chromosomes in the female. The possible mechanisms by which B chromosomes may cause undertransmission of the supernumerary segment, and the implications of this phenomenon for the maintenance of this extra chromosome segment, are discussed.Key words: supernumerary segments, B chromosomes, Mendelian transmission, grasshoppers.
Ultrastructural banding induced by DraI or HaeIII progressive digestion and in situ nick translation on human chromosomes
Authors: Coco Rosalba Del , Stuppia Liborio , Cinti Caterina , Peila Rita , Maraldi Nadir Mario
Published: May 2008

Fixed human metaphase chromosomes were progressively digested with DraI or HaeIII restriction enzymes, submitted to in situ nick translation, and observed by transmission electron microscopy to obtain further information on the localization of the endonuclease target sequences and on the conformational changes in chromosomal bands. This approach allows us to detect specific nick translation patterns, namely, G-banding or R-like banding after short DraI and HaeIII endonuclease digestion, respectively. Intermediate banding recognizable as C-negative banding and G + C banding are induced by longer HaeIII digestion, before the C-positive banding. These patterns appear to depend both on different target sites of the employed endonucleases and on the DNA loss at different digestion times.Key words: human chromosomes, in situ nick translation, DraI banding, HaeIII banding, electron microscopy.
The in situ localization of Adh transcripts in Drosophila species reveals evolved regulatory differences in spatially restricted expression
Authors: Ranganayakulu Gogineni
Published: May 2008

Spatial and temporal aspects of Adh expression were examined during oogenesis and embryogenesis of Drosophila melanogaster, D. simulans, and D. virilis by in situ hybridization. In stage 14 and 15 embryos, differences in zygotic expression of Adh in the primordia of the gastric caecae of D. simulans and in the fat body of D. virilis were observed. These zygotic differences appear to be transient because Adh expression is seen in the gastric caecae of stage 16 embryos of D. simulans and in the fat body of stage 17 embryos of D. virilis. Analysis of D. melanogaster × D. simulans hybrids revealed that the parental difference for transcriptional activity of Adh in the primordia of the gastric caecae is under dominant control. These results provide the basis for exploring evolved regulatory differences in Adh expression during oogenesis and embryogenesis of Drosophila, which are until now unexplored. The potential of in situ hybridization in analyzing evolved regulatory differences in gene expression is briefly discussed.Key words: Drosophila, Adh, tissue-specific expression, interspecific variation, in situ hybridization.
Pooled DNA for linkage analysis: practical and statistical considerations
Authors: Tinker N. A. , Mather D. E. , Fortin M. G.
Published: May 2008

In an F2 population, the alleles at two loci with a recombination fraction r < 0.5 are in linkage disequilibrium. If r is small, then a pool of DNA from k diploid individuals that are fixed at one locus has a relatively high probability (P = (1 − r)2k) of containing only the coupled allele at the second locus. Based on this principle, several methods have been described to detect linkage (using one or two pools) or to estimate r (using a group of n pools). This report compares maximum likelihood and approximate estimators of r for use in pooled-DNA analysis and illustrates the use of this analysis for dominant markers. Expected values and expected mean squares for estimators of r were computed for varying levels of r, k, and n. Both estimators were biased, but the bias and variability were slightly smaller for the maximum-likelihood estimator. Bias was not severe except when k was large relative to r and (or) n. Methods for optimizing k are discussed relative to several criteria: minimizing variance, minimizing bias, minimizing the probability that linkage cannot be detected, and minimizing the number of samples that must be screened.Key words: pooled DNA, linkage analysis, molecular markers, RAPD, genetic mapping.
Transmission analysis of mitotically unstable B chromosomes in Locusta migratoria
Authors: Pardo M. C. , López-León M. D. , Cabrero J. , Camacho J. P. M.
Published: May 2008

Seventeen controlled crosses in which the mitotically unstable B chromosome of Locusta migratoria was carried by one parent only have provided evidence that B chromosomes are significantly eliminated during sexual transmission in males, at a mean rate that almost counteracts the premeiotic accumulation derived from mitotic instability during germ line development. On the other hand, B chromosomes are significantly accumulated in females, presumably by their preferential migration to the secondary oocyte during the first meiotic division. These results substantially change the current knowledge about this B chromosome system, because the main B accumulation occurs in females and not in males, as was hitherto thought. Furthermore, this case shows that the maintenance of a single B system in natural populations may be the result of many different forces and mechanisms acting for and against B chromosomes.Key words: locust, Locusta migratoria, B chromosomes, accumulation mechanisms, meiotic drive, B elimination, parthenogenesis.
The molecular identification of the midget chromosome from the rye genome
Authors: Francki M. G. , Langridge P.
Published: May 2008

The diminutive "midget" chromosome is found in plants containing a wheat nuclear genome with a substituted rye cytoplasm. This cytoplasmic substituted line arose during successive backcrossing of a wheat/rye amphiploid to wheat as the recurrent male parent. Southern and in situ hybridization with a dispersed repeat sequence specific for rye, R173, indicates that the midget chromosome originates from within the rye genome. Various DNA markers previously mapped to group 1 chromosomes of wheat and barley were used to trace the origin of the midget chromosome from within the rye genome. Ten short arm and 36 long arm probes were used and one marker was identified, which hybridizes to the midget chromosome and maps to the proximal region of the long arm of chromosome 1R. An additional marker was generated from a genomic library of the line containing the midget chromosome. This also maps to the long arm of 1R. The results indicate that the midget chromosome contains a small segment of the long arm of chromosome 1R.Key words: midget chromosome, RFLP markers, chromosome 1R, repeated DNA sequence.
The distribution of cDNA sequences on field bean chromosomes
Authors: Houben A. , Brandes A. , Schubert I.
Published: May 2008

Total polyadenylated RNA was isolated from different organs of the field bean by oligo-dT latex particles. Complementary DNA (cDNA) was reverse transcribed from the mRNAs and used as a probe for fluorescent in situ hybridization to metaphase chromosomes. Hybridization signals covered the whole chromosome complement except for late-replicating Giemsa-banded heterochromatin regions, which are composed mainly (or exclusively) of tandemly arranged repetitive sequences.Key words: cDNA, field bean, fluorescent in situ hybridization.
Detection of genetic diversity in tea (Camellia sinensis) using RAPD markers
Authors: Wachira F. N. , Waugh R. , Powell W. , Hackett C. A.
Published: May 2008

Camellia sinensis is a beverage tree crop native to Southeast Asia and introductions have been made into several nonindigenous countries. No systematic assessment of genetic variability in tea has been done anywhere. In this study, random amplified polymorphic DNA (RAPD) analysis was used to estimate genetic diversity and taxonomic relationships in 38 clones belonging to the three tea varieties, assamica, sinensis, and assamica ssp. lasiocalyx. Extensive genetic variability was detected between species, which was partitioned into between and within population components. Seventy percent of the variation was detected within populations. Analyses based on band sharing separated the three populations in a manner consistent with both the present taxonomy of tea and with the known pedigrees of some clones. RAPD analysis also discriminated all of the 38 commercial clones, even those which cannot be distinguished on the basis of morphological and phenotypic traits.Key words: genetic diversity, RAPDs, Camellia sinensis.
Phylogenetic relationships of the monogenomic species of the wheat tribe, Triticeae (Poaceae), inferred from nuclear rDNA (internal transcribed spacer) sequences
Authors: Hsiao C. , Chatterton N. J. , Asay K. H. , Jensen K. B.
Published: May 2008

Phylogenetic relationships of 30 diploid species of Triticeae (Poaceae) representing 19 genomes were estimated from the sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA. The ITS sequence phylogeny indicated that: (i) each genome group of species is monophyletic, concordant with cytogenetic evidence; (ii) Hordeum (I) and Critesion (H) are basal; (iii) Australopyrum (W) is closely related to Agropyron (P); (iv) Peridictyon (G), Heteranthelium (Q), and Dasypyrum (V) are closely related to Pseudoroegneria (S); (v) most of the annuals, Triticum s.l. (A, B, D), Crithopsis (K), Taeniatherum (T), Eremopyrum (F), Henrardia (O), Secale (R), and two perennials, Thinopyrum (J) and Lophopyrum (E), all of Mediterranean origin, are a monophyletic group. However, phylogenetic trees based on morphology group these Mediteranean species with various perennial lineages of the Arctic-temperate region. The molecular data and biogeography of the tribe suggest that the Mediterranean lineage is derived from the Arctic-temperate lineage and that the two lineages have evolved in parallel. Extensive morphological parallelism apparently obscures the true genealogical history of the tribe when only morphology is considered.Key words: Poaceae, Triticeae, rDNA sequence, molecular phylogeny, parallel evolution.
A survey of DNA polymorphism within the genusCapsicumand the fingerprinting of pepper cultivars
Authors: Prince James P. , Lackney Vincent K. , Angeles Carmichael , Blauth James R. , Kyle Molly M.
Published: May 2008

Interspecific genetic variation was examined in the genus Capsicum based on shared restriction fragments in Southern analyses. Four distinct clusters were delineated among 21 accessions of cultivated and wild pepper (C. annuum, C. baccatum, C. chacoense, C. chinense, and C. frutescens). Three tight clusters comprised of accessions belonging to C. annuum, C. frutescens, and C. baccatum, respectively, were formed, along with a fourth cluster comprised of one accession each of C. chinense and C. chacoense. All accessions were differentiated by this technique, and the clusters corresponded closely to previous morphology-based classification. Sufficient DNA polymorphism exists among these accessions that segregating populations useful for restriction fragment length polymorphism (RFLP) mapping could be constructed using any two pepper accessions as parents. Regression analysis indicates that genetic distance is a good predictor (R2 = 0.872) of the level of mappable DNA polymorphism in Capsicum. Intraspecific variability was examined among four C. annuum cultivars (NuMex R Naky, Jupiter, Perennial, and Criollo de Morelos 334) using both RFLPs and randomly amplified polymorphic DNA (RAPDs), allowing a comparative evaluation of the two techniques. Seventeen percent of the clones used singly in RFLP analyses were sufficient for the differentiation of these varieties, as were 12.5% of the RAPD PCR amplifications. Dendrograms constructed from RFLP and RAPD analyses of the intraspecific data are similar but not identical. Southern analysis and RAPD PCR should be useful for DNA fingerprinting and the discrimination of closely related C. annuum genotypes.Key words: cluster analysis, restriction fragment length polymorphism, RFLP, DNA fingerprinting, randomly amplified polymorphic DNA, RAPD, germplasm.