W R Ellington

Bio: W R Ellington is an academic researcher from Florida State University. The author has contributed to research in topics: Phosphagen & Taurocyamine kinase. The author has an hindex of 1, co-authored 1 publications receiving 451 citations.

Evolution and physiological roles of phosphagen systems

Abstract: Phosphagens are phosphorylated guanidino compounds that are linked to energy state and ATP hydrolysis by corresponding phosphagen kinase reactions: phosphagen + MgADP + H(+) guanidine acceptor + MgATP. Eight different phosphagens (and corresponding phosphagen kinases) are found in the animal kingdom distributed along distinct phylogenetic lines. By far, the creatine phosphate/creatine kinase (CP/CK) system, which is found in the vertebrates and is widely distributed throughout the lower chordates and invertebrates, is the most extensively studied phosphagen system. Phosphagen kinase reactions function in temporal ATP buffering, in regulating inorganic phosphate (Pi) levels, which impacts glycogenolysis and proton buffering, and in intracellular energy transport. Phosphagen kinase reactions show differences in thermodynamic poise, and the phosphagens themselves differ in terms of certain physical properties including intrinsic diffusivity. This review evaluates the distribution of phosphagen systems and tissue-specific expression of certain phosphagens in an evolutionary and functional context. The role of phosphagens in regulation of intracellular Pi levels likely evolved early. Thermodynamic poise of the phosphagen kinase reaction profoundly impacts this capacity. Furthermore, it is hypothesized that the capacity for intracellular targeting of CK evolved early as a means of facilitating energy transport in highly polarized cells and was subsequently exploited for temporal ATP buffering and dynamic roles in metabolic regulation in cells displaying high and variable rates of aerobic energy production.

The spores of Phytophthora : weapons of the plant destroyer

Abstract: Members of the genus Phytophthora are among the most serious threats to agriculture and food production, causing devastating diseases in hundreds of plant hosts. These fungus-like eukaryotes, which are taxonomically classified as oomycetes, generate asexual and sexual spores with characteristics that greatly contribute to their pathogenic success. The spores include survival and dispersal structures, and potent infectious propagules capable of actively locating hosts. Genetic tools and genomic resources developed over the past decade are now allowing detailed analysis of these important stages in the Phytophthora life cycle.

Variation in the heat shock response and its implication for predicting the effect of global climate change on species' biogeographical distribution ranges and metabolic costs

Abstract: The preferential synthesis of heat shock proteins (Hsps) in response to thermal stress [the heat shock response (HSR)] has been shown to vary in species that occupy different thermal environments. A survey of case studies of aquatic (mostly marine) organisms occupying stable thermal environments at all latitudes, from polar to tropical, shows that they do not in general respond to heat stress with an inducible HSR. Organisms that occupy highly variable thermal environments (variations up to >20 degrees C), like the intertidal zone, induce the HSR frequently and within the range of body temperatures they normally experience, suggesting that the response is part of their biochemical strategy to occupy this thermal niche. The highest temperatures at which these organisms can synthesize Hsps are only a few degrees Celsius higher than the highest body temperatures they experience. Thus, they live close to their thermal limits and any further increase in temperature is probably going to push them beyond those limits. In comparison, organisms occupying moderately variable thermal environments (<10 degrees C), like the subtidal zone, activate the HSR at temperatures above those they normally experience in their habitats. They have a wider temperature range above their body temperature range over which they can synthesize Hsps. Contrary to our expectations, species from highly (in comparison with moderately) variable thermal environments have a limited acclimatory plasticity. Due to this variation in the HSR, species from stable and highly variable environments are likely to be more affected by climate change than species from moderately variable environments.

The proteomic response of the mussel congeners Mytilus galloprovincialis and M. trossulus to acute heat stress: implications for thermal tolerance limits and metabolic costs of thermal stress.

Abstract: The Mediterranean blue mussel, Mytilus galloprovincialis , an invasive species in California, has displaced the more heat-sensitive native congener, Mytilus trossulus , from its former southern range, possibly due to climate change. By comparing the response of their proteomes to acute heat stress we sought to identify responses common to both species as well as differences that account for greater heat tolerance in the invasive. Mussels were acclimated to 13°C for four weeks and exposed to acute heat stress (24°C, 28°C and 32°C) for 1 h and returned to 13°C to recover for 24 h. Using two-dimensional gel electrophoresis and tandem mass spectrometry we identified 47 and 61 distinct proteins that changed abundance in M. galloprovincialis and M. trossulus , respectively. The onset temperatures of greater abundance of some members of the heat shock protein (Hsp) 70 and small Hsp families were lower in M. trossulus . The abundance of proteasome subunits was lower in M. galloprovincialis but greater in M. trossulus in response to heat. Levels of several NADH-metabolizing proteins, possibly linked to the generation of reactive oxygen species (ROS), were lower at 32°C in the cold-adapted M. trossulus whereas proteins generating NADPH, important in ROS defense, were higher in both species. The abundance of oxidative stress proteins was lower at 32°C in M. trossulus only, indicating that its ability to combat heat-induced oxidative stress is limited to lower temperatures. Levels of NAD-dependent deacetylase (sirtuin 5), which are correlated with lifespan, were lower in M. trossulus in response to heat stress. In summary, the expression patterns of proteins involved in molecular chaperoning, proteolysis, energy metabolism, oxidative damage, cytoskeleton and deacetylation revealed a common loci of heat stress in both mussels but also showed a lower sensitivity to high-temperature damage in the warm-adapted M. galloprovincialis , which is consistent with its expanding range in warmer waters. * AAT : aspartate aminotransferase cdc42 : cell division control protein homolog 42 cMDH : cytosolic malate dehydrogenase CoA : coenzyme A EGFR : epidermal growth factor EST : expressed sequence tag ETC : electron transport chain Hsp : heat shock protein IDH : isocitrate dehydrogenase IPG : immobilized pH gradient MAPK : mitogen-activated protein kinase mMDH : mitochondrial malate dehydrogenase MOWSE : molecular weight search MS : mass spectrometry MVP : major vault protein NAD(H) : nicotinamide adenine dinucleotide (reduced form) NADP(H) : nicotinamide adenine dinucleotide phosphate (reduced form) PCA : principle component analysis PDH : pyruvate dehydrogenase PEPCK : phosphoenolpyruvate carboxykinase pI : isoelectric point PMF : peptide mass fingerprint PTM : post-translational modification ROS : reactive oxygen species sHsps : small heat shock proteins SOD : superoxide dismutase TFA : trifluoroacetic acid T on : onset temperature 2-D GE : two-dimensional gel electrophoresis