A candidate for Lr19, an exotic gene conditioning leaf rust resistance in wheat

Lr19, one of the few widely effective genes conferring resistance to leaf rust in wheat, was transferred from the wild relative Thinopyrum ponticum to durum wheat. Since Lr19 confers a hypersensitive response to the pathogen, it was considered likely that the gene would be a member of the major nucleotide-binding site (NBS)-leucine-rich repeat (LRR) plant R gene family. NBS profiling, based on PCR amplification of conserved NBS motifs, was applied to durum wheat–Th. ponticum recombinant lines involving different segments of the alien 7AgL chromosome arm, carrying or lacking Lr19. Differential PCR products were isolated and sequenced. From one such sequence (AG15), tightly linked to Lr19, a 4,121-bp full-length cDNA was obtained. Its deduced 1,258 amino acid sequence has the characteristic NBS-LRR domains of plant R gene products and includes a coiled-coil (CC) region typical of monocots. The genomic DNA sequence showed the presence of two exons and a short intron upstream of the predicted stop codon. Homology searches revealed considerable identity of AG15 with the cloned wheat resistance gene Pm3a and a lower similarity with wheat Lr1, Lr21, and Lr10. Quantitative PCR on leaf-rust-infected and non-infected Lr19 carriers proved AG15 to be constitutively expressed, as is common for R genes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A site-specific recombination function in Staphylococcus aureus plasmids.

All known small staphylococcal plasmids possess one or two recombination sites at which site-specific cointegrate formation occurs. One of these sites, RSA, is present on two small multicopy plasmids, pT181 and pE194; it consists of 24 base pairs of identity in the two plasmids, the "core," flanked by some 50 base pairs of decreasing homology. Here we show that recombination at RSA is recA independent and is mediated by a plasmid-encoded, trans-acting protein, Pre (plasmid recombination). Pre-mediated recombination is site specific in that it occurs within the core sequence of RSA in a recA1 host. Recombination also occurs between two intramolecular RSA sites. Unlike site-specific recombination systems encoded by other plasmids, Pre-RSA is not involved in plasmid maintenance.     

A bunch-oligonucleotide forming stable monomolecular quadruplex containing a T-tetrad

The chemical synthesis of bunch-ODN I and II prone to form quadruplex structures containing G-and T-tetrads has been reported. Structural studies were performed by 1H-NMR and CD melting experiments.     

Cellular localization of bovine pancreatic trypsin inhibitor and related molecular forms in bovine lung

Summary In addition to bovine pancreatic trypsin inhibitor (BPTI), three BPTI-related molecular forms (isoinhibitors I, II and III) were isolated from bovine lung by affinity chromatography on immobilized trypsin and subsequently purified by Fast Protein Liquid Chromatography. These inhibitors are identical to the isoinhibitors previously isolated from bovine spleen. Their localization in bovine lung was studied by immunohistochemical techniques, using two different immunoglobulin preparations, selectively recognizing BPTI or the other molecular forms.BPTI-related immunoreactivity was found to be restricted to isolated cells, often identified as mast cells by Toluidine Blue staining. In contrast, isoinhibitor-related immunoreactivity, which also occurs in the mast cells, is present in a number of other cell types. These types include: (i) the smooth muscle cells of different calibre vessels, (ii) the ciliated cells of the bronchial epithelium and the related mucus, and (iii) many cells at alveolar level.Comparison of these data with previous results obtained for bovine spleen suggest multiple physiological roles for these inhibitors.     

NMR solution structure of the acylphosphatase from Escherichia coli

The solution structure of Escherichia coli acylphosphatase (E. coli AcP), a small enzyme catalyzing the hydrolysis of acylphosphates, was determined by (1)H and (15)N NMR and restrained modelling calculation. In analogy with the other members of AcP family, E. coli AcP shows an alpha/beta sandwich domain composed of four antiparallel and one parallel beta-strand, assembled in a five-stranded beta-sheet facing two antiparallel alpha-helices. The pairwise RMSD values calculated for the backbone atoms of E. coli and Sulfolobus solfataricus AcP, Bovine common type AcP and Horse muscle AcP are 2.18, 5.31 and 5.12 A, respectively. No significant differences are present in the active site region and the catalytic residue side chains are consistently positioned in the structures.     

Secretion of alpha-amylase from Pseudoalteromonas haloplanktis TAB23: two different pathways in different hosts

Secretion of cold-adapted alpha-amylase from Pseudoalteromonas haloplanktis TAB23 was studied in three Antarctic bacteria. We demonstrated that the enzyme is specifically secreted in the psychrophilic hosts even in the absence of a protein domain that has been previously reported to be necessary for alpha-amylase secretion in Escherichia coli. The occurrence of two different secretion pathways in different hosts is proposed.