2,338 research outputs found
Purification and Properties of a Unique Nucleotide Pyrophosphatase/Phosphodiesterase I That Accumulates in Soybean Leaves in Response to Fruit Removal
cDNA Sequence for the Ribulose 1,5 Bisphosphate Carboxylase/Oxygenase Complex Protein (A Protein that Accumulates in Soybean Leaves in Response to Fruit Removal)
Moderately High Temperatures Inhibit Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase (Rubisco) Activase-Mediated Activation of Rubisco
The Two Forms of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Differ in Sensitivity to Elevated Temperature
Heat tolerance in a wild Oryza species is attributed to maintenance of Rubisco activation by a thermally stable Rubisco activase ortholog
⹠The response of photosynthesis and plant growth to short periods of supra-optimal heat was tested in rice (Oryza sativa) and two wild Oryza species from the Australian savanna, O. meridionalis and O. australiensis. The mechanism of heat tolerance in the wild species was explored, particularly focusing on the heat-labile protein Rubisco activase (RCA). ⹠We compared leaf elongation rates, net photosynthesis and Rubisco activation state at moderate (28°C) and high temperature (45°C). Sequence analysis followed by enzyme kinetics of RCA was used to identify structural differences and thermal stability. ⹠Oryza australiensis was the most heat-tolerant species. Rubisco activation state was positively correlated with leaf elongation rates across all three species at four times following exposure to 45°C. Oryza australiensis had multiple polymorphisms in the RCA primary protein sequence, and the protein was thermally stable up to 42°C relative to RCA from O. sativa which became inhibited at 36°C. ⹠We attribute the heat tolerance of growth and photosynthesis in these wild species to thermal stability of RCA, enabling Rubisco to remain active. Because thermal stability of RCA in O. australiensis co-occurs with reduced enzyme specific activity, an increased RCA to Rubisco ratio is required in vivo to maintain high Rubisco activation
Improving the thermal stability of Rubisco activase
The major objective is to produce wheat germplasm with improved tolerance to heat stress through the modification of the key photosynthetic enzyme Rubisco activase. Current funds have allowed transformation of âbest betâ candidate gene constructs into wheat as part of SP1.5. Joanna Scales, a BBSRC PhD student jointly supervised by Martin Parry, Christine Raines, and Mike Salvucci, generated the transformation constructs and will undertake the molecular and biochemical analysis of transgenic lines
Improving the thermal stability of Rubisco activase
The thermal sensitivity of the key photosynthetic enzyme Rubisco activase limits wheat photosynthesis at moderately high temperatures. Introduction of a more thermal tolerant form of Rubisco activase, such as that from cotton, into wheat is predicted to broaden the temperature range of optimal Rubisco activation and photosynthetic CO2 assimilation. Transgenic lines have been produced to express the cotton Rubisco activase in wheat and current efforts are characterizing the most promising lines for further studies of photosynthetic performance at moderately high temperatures. Joanna Scales, a BBSRC PhD student jointly supervised by Martin Parry, Christine Raines, and Mike Salvucci, generated the transformation constructs and will undertake the molecular and biochemical analysis of the transformant lines. It is predicted that the cotton Rubisco activase will confer superior thermal tolerance to wheat photosynthesis
Systems analysis of protein signatures predicting cetuximab responses in KRAS, NRAS, BRAF and PIK3CA wild-type patient-derived xenograft models of metastatic colorectal cancer
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Interactions between cytoplasmic and nuclear genomes confer sexâspecific effects on lifespan in Drosophila melanogaster
Genetic variation outside of the cell nucleus can affect the phenotype. The cytoplasm is home to the mitochondria, and in arthropods often hosts intracellular bacteria such as Wolbachia. Although numerous studies have implicated epistatic interactions between cytoplasmic and nuclear genetic variation as mediators of phenotypic expression, two questions remain. Firstly, it remains unclear whether outcomes of cyto-nuclear interactions will manifest differently across the sexes, as might be predicted given that cytoplasmic genomes are screened by natural selection only through females as a consequence of their maternal inheritance. Secondly, the relative contribution of mitochondrial genetic variation to other cytoplasmic sources of variation, such as Wolbachia infection, in shaping phenotypic outcomes of cyto-nuclear interactions remains unknown. Here, we address these questions, creating a fully crossed set of replicated cyto-nuclear populations derived from three geographically distinct populations of Drosophila melanogaster, measuring the lifespan of males and females from each population. We observed that cyto-nuclear interactions shape lifespan and that the outcomes of these interactions differ across the sexes. Yet, we found no evidence that placing the cytoplasms from one population alongside the nuclear background of others (generating putative cyto-nuclear mismatches) leads to decreased lifespan in either sex. Although it was difficult to partition mitochondrial from Wolbachia effects, our results suggest at least some of the cytoplasmic genotypic contribution to lifespan was directly mediated by an effect of sequence variation in the mtDNA. Future work should explore the degree to which cyto-nuclear interactions result in sex differences in the expression of other components of organismal life history
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