Characterization ofSolanum tuberosum simple sequence repeats and application to potato culiwar identification

With the continued introduction of new potato cultivars, accurate identification is becoming difficult but is essential for maintaining cultivar integrity and Plant Breeders’ Rights. Hypervariable DNA sequences, referred to as simple sequence repeats (SSRs) or microsatellites, have been reported to be an excellent source of genetic markers. To determine the abundance, distribution, and composition of SSRs withinSolanium tuberosum, 252 sequences were searched for tetranucleotide and smaller SSRs with a minimum length of 20 nucleotides and a maximum discrepancy of two nucleotides. In total, 40 unique SSRs were observed in the 252S. tuberosum sequences examined and occurred at a frequency of one SSR every 8.1 kb. To assess the ability of site-specific amplified SSRs to identify potato cultivars, a simple (TCAC)_m and compound (TCAC)_m ? (CTT)_n SSR 5’ to the starch synthase gene and a compound (C)_p ? (CT)_q ? (AT)_r ? (G)_s SSR 5’ to the sequence encoding mature proteinase inhibitor I, were examined and shown to produce unique DNA profiles for 73 of 95 tetraploid cultivars. In total, 24 alleles were observed at these loci and the accurately sized amplified DNA products can be used to establish a database for cultivar identification. Site-specific amplified alleles were somatically stable and have been conserved in clonal variants of Russet Burbank independently maintained for almost seven decades, a characteristic essential for cultivar identification. As genetic markers, the abundant, informative, and easily examined site-specific amplified alleles of SSRs are ideal for quickly and accurately determining cultivar identity of S.tuberosum ssp.tuberosum.     

Dual-label time-resolved fluoroimmunoassay for simultaneous quantification of haptoglobin and C-reactive protein in meat juice from pigs

A new method was developed to simultaneously measure 2 acute-phase proteins (APPs) by time-resolved immunofluorometry. The assay, based on double-label quantification of haptoglobin (Hp) and C-reactive protein (CRP) in meat juice samples from pigs, was constructed by use of a combination of europium and samarium chelate lanthanides as labels. Meat juice samples from 154 pigs were used for analytic and clinical validation of the assay through determination of precision, accuracy, limit of detection, and quantification. The analytic performance of the assay was satisfactory, with good intra-assay and interassay precision and accuracy. The levels of Hp and CRP were increased in the meat juice samples of diseased animals compared with healthy ones. According to the results, higher sensitivity could be achieved if the cut-off values of both proteins were taken into account for clinical relevance rather than used individually. Since the dual assay saved both time and sample, it could be used as a rapid and sensitive screening test in porcine production.     

Hybrid grass-clump dwarfness in wheat: Physiology and genetics

Summary The growth of all grass-clump dwarfs is sensitive to temperature with low temperature giving rise to the grass-clump phenotype and high temperature producing normal phenotype. A continuous temperature of 26°C is required for normal growth of Type 1 dwarfs, a continuous temperature of 21°C is required for normal growth of Ty[e 2 dwarfs and a continuous temperature of 16°C is required for normal growth of Type 3 dwarfs.Genetic studies show that the inheritance of the grass-clump characteristic is due to three complementary dominant genes.The grass-clump growth habit is produced as a result of the temperature sensitivity of the apical meristem. In grass-clump plants low temperature treatment results in the cessation of cell division, DNA synthesis and phospholipid synthesis in the apical meristem. The primary temperature lesion has not been identified. Prolonged low temperature treatment of grass-clump plants results in extensive cell necrosis in a region just below the apical meristem; this cell death results in the permanent inactivation of the apical meristem.Supported in part by the National Research Council of Canada.