Restriction fragment analysis of the secalin loci of rye

Analyses of wheat/rye addition lines by Southern blotting confirmed the presence of sequences related to theSec 1, Sec 2, andSec 3 loci on chromosomes 1R and 2R. Comparison of the 1R and 2R addition lines allowed the identification of -secalin genes atSec 1 andSec 2, respectively, while -secalin and -secalin genes atSec 1 were discriminated by comparative hybridization with three probes: -secalin, total -secalin, and 3 -secalin. The high molecular weight (HMW) secalin genes atSec 3 were identified using a homologous HMW subunit probe from wheat. Gene copy numbers were estimated as about 40–60 for -secalins, 5–10 for -secalins, and 2 for HMW secalins. Comparison of individual plants of cv. Gazelle showed a high degree of polymorphism, particularly for sequences related to -secalins and HMW secalins.     

Identification and characterization of the functional alpha origin of DNA replication of the R6K plasmid and its relatedness to the R6K beta and gamma origins

Summary The functional R6K origin is composed of two DNA elements, one of 580 bp carrying the origin sequences and the other of 277 bp containing the seven 22 bp direct repeats previosly identified as also required for and origin activity. These two genetic elements are separated by approximately 3,000 bp of R6K sequences which are dispensable for origin activity. The function of the origin depends on the presence in cis of the 580 bp and the 277 bp fragments and requires that they be oriented as in the intact R6K. Activation of the origin depends on the R6K replication initiation protein .Within the 580 bp of the origin, there is a sequence of 98 bp which appears as an inverted repeat of 96 bp in the replicon. Deletion of the 96 bp or 98 bp results in inactivation of the and the origins respectively. These long repeats are palindromic and it is suggested that these may serve as the recognition signals for initiation of DNA replication in the and the origins of R6K. DNA homology analysis performed on , and origin sequences, also reveals 10–23 bp sequences in the and the origins that are related to the family of 22 bp direct repeats in the origin which were shown previously to be binding sites for the protein.     

DNA variants within the 5′-flanking region of milk-protein-encoding genes II. The β-lactoglobulin-encoding gene

For the detection of polymorphisms within the 5-flanking region of the -lactoglobulin (-LG) -encoding gene a nucleotide sequence containing 795 bp of the promoter and 59 bp of exon I was cloned and sequenced. After comparing the sequence from the DNA of 11 diverse cows (different breeds and milk-protein yields), 14 singlebp substitutions were identified within the 5-flanking region and two in the 5-untranslated region (5-UTR) of exon I. Some of the variants are located in potential binding sites for trans-acting factors or in the 5-UTR. A PCR-based RFLP analysis was performed, and the genotypes of an additional 60 cows were identified at five variable 5-flanking sites. The results reveal three frequent combinations between the A and B alleles of the protein-coding region and the novel 5-flanking DNA variants. This finding may explain the differences of the protein-variant-dependent -LG synthesis (A>B) observed in vivo. A sequence comparison of the bovine and ovine promoters reveals an homology of 92.8% and shows a higher degree of conservation between positions -600 and -300.     

Molecular characterization of β-thalassemia in Czechoslovakia

Summary We have identified different -thalassemia mutations in 93 members of 34 families of Czech or Slovakian descent using gene amplification, hybridization with specific ³²P-labeled oligonucleotide probes, sequencing of amplified DNA, and gene mapping. The GA mutation at IVS-I-1 was found in 18 families; other Mediterranean mutations were IVS-II-1 (GA), IVS-II-745 (CG), IVS-I-110 (GA), and codon 39 (CT); these were present in 9 additional families. The GT mutation at codon 121, known to cause Heinzbody -thalassemia, was present in 3 families, and the frameshift at codons 82/83 (-G), first described in the Azerbaijanian population, in 2 families. A newly discovered allele was a frameshift at codons 38/39 (-C). One -thalassemia allele was incompletely characterized. We observed in 2 families a TC mutation at position +96 UTR (untranslated region) relative to the termination codon; this mutation likely is a rare polymorphism, -Thalassemia was rare; only one person carried the -^3.7 heterozygosity, and one other had a yet to be identified -thalassemia-1, while seven had the ^{anti 3.7} triplication.     

Linkage mapping of the cystathionine β-synthase (CBS) gene on human chromosome 21 using a DNA polymorphism in the 3′ untranslated region

We used single-strand conformation polymorphism (SSCP) to detect DNA polymorphisms in the 3 untranslated (3UT) region of the gene for cystathionine -synthase (CBS). A polymorphism due to a T-to-C substitution at nucleotide 549 of the 3UT region with heterozygosity of 46% has been identified. Genotypes for this polymorphism have been obtained in all of the informative CEPH families, and CBS has been placed in the linkage map of human chromosome 21.     

Wheat specific repetitive DNA sequences — construction and characterization of four different genomic clones

Summary The construction and molecular analysis of four recombinant clones — pTa1, pTa2, pTa7, and pTa8 — is described. The four clones contain different highly repeated sequences of genomic DNA from Triticum aestivum variety Chinese Spring. The wheat specificity has been determined by colony and dot blot hybridization in comparison with total rye DNA (Secale cereale variety Petka). The four clones with a variable degree of specificity were compared by sequence analysis after the recloning of wheat DNA inserts into M13 mp8. Within the sequencing data a tendency can be observed that those repeated sequences which show the highest degree of species specificity contain a significantly increased amount of GC residues.     

Genetic polymorphism at the κ chain locus in mice: Comparisons of restriction enzyme hybridization fragments of variable and constant region genes

Variable (V) and constant (C) region genes of the mouse kappa light chain have been compared in inbred strains and in geographically isolated or genetically separated populations of mice by Southern blot analysis of endonuclease-restricted germline DNA. In most cases, the C gene is found on a single restriction fragment while the V genes of the V19 and V21 groups are each found on several (6–18) fragments. The restriction fragment (RF) patterns of V19 and V21 groups are both polymorphic when compared among inbred mouse strains. Southern blot patterns of V21 and V19 of inbred strains are also found among some geographically isolated populations of mice, suggesting that inbred strains acquired kappa loci from different subspecies. Some populations of geographical isolates show V21, V19, and C contexts similar to inbred mice while more distantly related species within the genus Mus and laboratory rats show no apparent similarity in context to inbred strains. Variable region genes determining the RF patterns of V19 and V21 appear to be linked to each other and to the C and Lyt-3 loci.     

Determination and evaluation of the sequence and textural effects of the puroindoline a and puroindoline b genes in a population of synthetic hexaploid wheat

Aegilops tauschii (2n=2 x=14, DD) is a rich source of genetic variability for hexaploid wheat (Triticum aestivum, 2n=6 x=42, AABBDD) improvement. This variability can be accessed through utilizing synthetic hexaploid wheat lines, which contain genomes from Ae. tauschii and T. turgidum (2n=4 x=28, AABB). Numerous desirable characteristics can and have been introgressed into common hexaploid wheat with this germplasm. In this work, the genetic variability in the two puroindoline genes (a and b) contained on the D genome, and the relationship that sequence polymorphisms in these genes have on endosperm texture among a population of 75 CIMMYT synthetic hexaploid accessions is described. Kernel texture was evaluated using the single kernel characterization system (SKCS). Kernel texture differed significantly (P0.0001) among the synthetic hexaploid accessions (range 2.6–40.9) and the parent types, durum or Ae. tauschii. The interaction term between parent types was also a significant effect (P0.0001). In addition to the wild-type protein sequences of the puroindoline genes (those present in Chinese Spring and all other soft wheats), three other translated sequences were identified in puroindoline a and two others in puroindoline b. These protein sequences were associated with significantly (P0.0001) softer endosperm textures than the wild-type protein sequences. As the softer alleles are expressed in a hexaploid background, they are immediately available to wheat breeding programs.     

Expression of a chimeric stilbene synthase gene in transgenic wheat lines

A chimeric stilbene synthase (sts)gene was transferred into wheat. Stilbene synthases play a role in the defence against fungal diseases in some plant species (e.g. groundnut or grapevine) by producing stilbenetype phytoalexins like resveratrol. Resveratrol is also claimed to have positive effects to human health. Embryogenic scutellar calli derived from immature embryos of the two commercial German spring wheat cultivars Combi and Hanno were used as target tissue for cotransformation by microprojectile delivery. The selectable marker/reporter gene constructs contained the bargene either driven by the ubiquitinpromoter from maize (pAHC 25, also containing the uidAgene driven by the ubiquitinpromoter), or by the actinpromoter (pDM 302) from rice. The cotransferred plasmid pStil 2 consisted of a grapevine stscoding region driven by the ubiquitin promoter. Eight transgenic Combi and one Hanno T_Oplant were obtained and, except one Combi T_Oplant, found to be cotransformants due to the integration of both the stsgene and the selectable marker or reporter genes. Expression of the stsgene was proven by RTPCR, and, for the first time, by detection of the stilbene synthase product resveratrol by HPLC and mass spectrometry. The stsgene was expressed in four of the seven transgenic Combi T_{_o}plants. Two of the respective T₁progenies segregated in a Mendelian manner were still expressing the gene. Investigations into methylation of the stsgene showed that in three nonexpressing progenies inactivation was paralleled by methylation.     

Organelle genome stability in anther-derived doubled haploids of wheat (Triticum aestivum L., cv. ‘Moisson’)

Summary Chloroplast and mitochondrial compartments of a parental line of wheat (Triticum aestivum L., cv. Moisson) and its anther-derived doubled haploid lines have been analyzed and compared on the basis of their DNA restriction patterns. The results obtained show that no noticeable difference can be detected between doubled haploid lines and parental line at the level of ctDNA and mtDNA organization. It may be concluded that in vitro culture by itself does not systematically generate a cytoplasmic variation in germ cells.