A non-representational approach to imagined action

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Taxonomic and Ecogeographic Predictors of Resistance Against Phthorimaea operculella Zeller in Wild Potato Tubers

Taxonomic and ecogeographic information are potentially useful to select plants with beneficial traits for crop breeding. We tested the predictability of taxonomic and geoclimatic information in identifying wild potatoes with resistance in tubers to the potato tuber moth, Phthorimaea operculella Zeller. We tested the tubers of 47 wild potato species and the native potato Solanum tuberosum andigena for resistance to tuber moth larvae. Materials included 6585 genotypes representing 558 accessions. During screening, 28% of accessions had ≥ 60% undamaged tubers (moderate resistance) and of these, 10% were highly resistant to moth damage (i.e., ≥ 80% of tubers undamaged). Tubers of six potato species (S. commersonii, S. chiquidenum, S. albicans, S. acaule, S. demissum and S. boliviense) were significantly more resistant than tubers of S. tuberosum andigena, but resistant accessions also occurred among 22 other Solanum species. The frequency of resistant accessions was similar across phylogenetic clades, but resistance was more frequent in accessions with an endosperm balance number (EBN) of 1 or 4 and a ploidy level of 4 × or 6 × . There was no apparent relation between altitude of origin and tuber resistance. Ecogeographical information was weakly related to resistance in some potato species; minimum temperatures during the coldest months at collection sites were positively related to resistance in S. boliviense and S. medians. Mean high temperatures and summertime precipitation were positively related to resistance in S. microdontum and S. acaule, respectively; however, ecogeographic information was not generally useful in predicting tuber resistance for other species or across all species. We recommend improvements to the phenotyping of potato accessions for resistance to tuber moth, including the use of taxonomic predictors

Symbiont-mediated adaptation by planthoppers and leafhoppers to resistant rice varieties

For over 50 years, host plant resistance has been the principal focus of public research to reduce planthopper and leafhopper damage to rice in Asia. Several resistance genes have been identified from native varieties and wild rice species, and some of these have been incorporated into high-yielding rice varieties through conventional breeding. However, adaptation by hoppers to resistant rice has been phenomenally rapid, and hopper populations with virulence against several resistance genes are now widespread. Directional genetic selection for virulent hoppers seems unlikely given the rapid pace of adaptation reported from field and laboratory studies. Among the alternative explanations for rapid hopper adaptation are changes (genetic, epigenetic, or community structure) in endosymbiont communities that become advantageous for planthoppers and leafhoppers that feed on resistant rice varieties. This review examines the nature of these symbiont communities and their functions in planthoppers and leafhoppers—focusing on their likely roles in mediating adaptation to plant resistance. Evidence from a small number of experimental studies suggests that bacterial and eukaryotic (including yeast-like) symbionts can determine or mediate hopper virulence on rice plants and that symbiont functions could change over successive generations of selection on both resistant and susceptible plants. The review highlights the potential complexity of rice hopper–symbiont interactions and calls for a more careful choice of research materials and methods to help reduce this complexity. Finally, the consequences of symbiont-mediated virulence adaptation for future rice breeding programs are discussed

Varied responses by yeast-like symbionts during virulence adaptation in a monophagous phloem-feeding insect

This study examines the three-way interaction between symbionts, insect herbivores and their host plants during adaptation to resistant crop varieties. We conducted a long-term selection study (20 generations of continuous rearing) with a monophagous phloem-feeder, the brown planthopper [Nilaparvata lugens (Stål)], on several resistant rice (Oryza sativa L.) varieties. Planthopper fitness and the abundance of yeast-like symbionts (YLS) were monitored throughout the selection process. N. lugens populations collected from six regions in the Philippines adapted to the resistant varieties as noted by increasing body size and increased egg-laying. Adaptation was partially through physiological and behavioral changes apparent during feeding: Planthoppers on resistant plants had relatively high levels of xylem feeding compared with planthoppers on susceptible plants. YLS densities were highly dependent on the host rice variety. However, there were no consistent trends in YLS density during host plant switching and virulence adaptation: Compared to densities in planthoppers on the standard susceptible variety Taichung Native 1 (TN1), YLS densities were consistently higher on PTB33 (resistant), similar on IR62 (resistant) and IR65482 (moderately resistant) but lower on IR22 (susceptible). Furthermore, YLS densities often remained the same despite improved planthopper fitness over generations. Our results do not support the hypothesis that changes in YLS density mediate planthopper adaptation to resistant varieties. However, slight reductions in YLS densities toward the end of selection on TN1, IR22 and IR62 may indicate that YLS have lower functional significance where varieties and environmental conditions are constant between generations

Variation in protein levels obtained from human blood cells and biofluids for platelet, peripheral blood mononuclear cell, plasma, urine and saliva proteomics

Blood cells and biofluid proteomics are emerging as a valuable tool to assess effects of interventions on health and disease. This study is aimed to assess the amount and variability of proteins from platelets, peripheral blood mononuclear cells (PBMC), plasma, urine and saliva from ten healthy volunteers for proteomics analysis, and whether protein yield is affected by prolonged fasting. Volunteers provided blood, saliva and morning urine samples once a week for 4 weeks after an overnight fast. Volunteers were fasted for a further 24 h after the fourth sampling before providing their final samples. Each 10 mL whole blood provided 400–1,500 μg protein from platelets, and 100–600 μg from PBMC. 30 μL plasma depleted of albumin and IgG provided 350–650 μg protein. A sample of morning urine provided 0.9–8.6 mg protein/dL, and a sample of saliva provided 70–950 μg protein/mL. None of these yields were influenced by the degree of fasting (overnight or 36 h). In conclusion, in contrast to the yields from plasma, platelets and PBMC, the protein yields of urine and saliva samples were highly variable within and between subjects. Certain disease conditions may cause higher or lower PBMC counts and thus protein yields, or increased urinary protein levels

Metabolomics of prolonged fasting in humans reveals new catabolic markers

Fasting is one of the simplest metabolic challenges that can be performed in humans. We here report for the first time a comprehensive analysis of the human "fasting metabolome" obtained from analysis of plasma and urine samples in a small cohort of healthy volunteers, using nuclear magnetic resonance (NMR), gas chromatography- and liquid chromatography-mass spectrometry (GC-MS and LC-MS). Intra- and inter-individual variation of metabolites was on measurement of four overnight fasting samples collected from each volunteer over a four week period. One additional sample per volunteer was collected following a prolonged fasting period of 36 h. Amongst a total of 377 quantified entities in plasma around 44% were shown to change significantly in concentration when volunteers extended fasting from 12 to 36 h. In addition to known markers (plasma free fatty acids, glycerol, ketone bodies) that reflect changes in the body's fuel management under fasting conditions a wide range of "new" entities such as a-aminobutyrate as well as other amino and keto acids were identified as fasting markers. Based on multiple correlations amongst the metabolites and selected hormones in plasma such as leptin or insulin-like-growth-factor-1 (IGF-1), a robust metabolic network with coherent regulation of a wide range of metabolites could be identified. The metabolomics approach described here demonstrates the plasticity of human metabolism and identifies new and robust markers of the fasting state. © 2010 Springer Science+Business Media, LLC. Chemicals/CAS: 2 aminobutyric acid, 80-60-4; glycerol, 56-81-5; somatomedin C, 67763-96-