Haploid barley from the intergeneric cross Hordeum vulgare x Psathyrostachys fragilis

Summary The intergeneric hybrid Hordeum vulgare x Psathyrostachys fragilis was fairly easily obtained. During each growing season the intermediate, perennial hybrid yielded haploid tillers of H. vulgare. Late in one season few, hybrid tillers headed. The morphology, cytology and enzymatic patterns of hybrid and haploid tillers were investigated.     

Genetic variation and control of plant regeneration in leek (Allium ampeloprasum L.)

Zygotic embryos of leek (Allium ampeloprasum L.) were isolated from mature seeds of different cultivars, selfings and full-sib families. The embryos were cultured on callus induction and shoot regeneration medium and employed to study several parameters: percentage of embryos forming calluses, percentage of embryos forming compact calluses, callus weight, percentage of regenerating calluses, numbers of shoot primordia and numbers of regenerated shoots. Differences between cultivars and selfings were found for most parameters studied. For all cultivars all parameters, except callus weight, decreased after one generation of selfing. Compact callus types enhanced primordia formation and shoot regeneration. Genetic characteristics of callus development and plant regeneration were studied in a 4 × 4 diallel cross. Analysis of variance revealed significant differences between full-sib families. The diallel analysis showed that additive gene effects were significant for all parameters. The predominance of additive gene effects indicated high narrow-sense heritability. Breeding for an increased number of regenerated shoots was successful.     

Population structure of Phytophthora infestans in China – geographic clusters and presence of the EU genotype Blue_13

The population structure of Phytophthora infestans in China was studied and three mitochondrial haplotypes (Ia, IIa, IIb) were observed. Genetic analysis with 10 highly informative SSR markers identified 68 different genotypes, including three dominant clonal lineages. In the Chinese P. infestans population, the genotypes were strongly clustered according to their geographic origin. One of dominant clonal lineages was genetically similar to Blue_13, a dominant clonal lineage found in Europe since 2004. This is the first report of Blue_13 outside Europe. Only one mating type (A1) was found in the northern and southeastern provinces, but in southern and northwestern China both mating types were observed. The mating type ratio and SSR allele frequencies indicate that in China the sexual cycle of P. infestans is rare. These results emphasize that the migration of asexual propagules and the generation of subclonal variation are the dominant driving factors of the population structure of P. infestans in China. They may also have implications for the role of monitoring P. infestans populations in potato late blight management strategies in China.     

Chondritic meteorite fragments associated with the Permian-Triassic boundary in Antarctica

Multiple chondritic meteorite fragments have been found in two sedimentary rock samples from an end-Permian bed at Graphite Peak in Antarctica. The Ni/Fe, Co/Ni, and P/Fe ratios in metal grains; the Fe/Mg and Mn/Fe ratios in olivine and pyroxene; and the chemistry of Fe-, Ni-, P-, and S-bearing oxide in the meteorite fragments are typical of CM-type chondritic meteorites. In one sample, the meteoritic fragments are accompanied by more abundant discrete metal grains, which are also found in an end-Permian bed at Meishan, southern China. We discuss the implications of this finding for a suggested global impact event at the Permian-Triassic boundary.     

Quinoxalinediones: potent competitive non-NMDA glutamate receptor antagonists

The N-methyl-D-aspartate (NMDA)-subtype of glutamate receptors has been well described as a result of the early appearance of NMDA antagonists, but no potent antagonist for the "non-NMDA" glutamate receptors has been available. Quinoxalinediones have now been found to be potent and competitive antagonists at non-NMDA glutamate receptors. These compounds will be useful in the determination of the structure-activity relations of quisqualate and kainate receptors and the role of such receptors in synaptic transmission in the mammalian brain.     

Evaluation of dihaploid populations from potato varieties and breeding lines

Summary Dihaploid populations from 20 varieties and 11 breeding lines ofSolanum tuberosum differed greatly in the occurrence and frequency of mutant phenotypes, in tuberization, flowering, pollen stainability, 2n-pollen production and resistance toGlobodera rostochiensis pathotype Ro-1. One population contained up to 61.7% lethal mutants: 39.1% of the total of 5377 dihaploids obtained did not tuberize, and 32.4% of 825 vigorous dihaploids did not flower. Of 825 vigorous dihaploids, 26.9 and 3.9% respectively had a pollen stainability higher than 20 and 60%. Among 222 dihaploids with a pollen stainability higher than 20%. 23.0% produced some 2n-pollen and none of these had a stainability higher than 60%. Among the dihaploid populations investigated the proportion of resistant to susceptible dihaploids ranged from 8:26 to 62:8.     

Does oxidation affect the water functionality of myofibrillar proteins?

Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.     

Homogenization conditions affect the oxidative stability of fish oil enriched milk emulsions: lipid oxidation

In this study fish oil was incorporated into commercial homogenized milk using different homogenization temperatures and pressures. The main aim was to understand the significance of homogenization temperature and pressure on the oxidative stability of the resulting milks. Increasing homogenization temperature from 50 to 72 degrees C decreased droplet size only slightly, whereas a pressure increase from 5 to 22.5 MPa decreased droplet size significantly. Surprisingly, emulsions having small droplets, and therefore large interfacial area, were less oxidized than emulsions having bigger droplets. Emulsions with similar droplet size distributions, but resulting from different homogenization conditions, had significantly different oxidative stabilities, indicating that properties of significance to oxidation other than droplet size itself were affected by the different treatments. In general, homogenization at 72 degrees C appeared to induce protective effects against oxidation as compared to homogenization at 50 degrees C. The results thus indicated that the actual composition of the oil-water interface is more important than total surface area itself.