Isoform-specific downregulation of peroxiredoxin in human failing myocardium

Peroxiredoxins (Prx) are a family of antioxidant thioredoxin or glutathione dependent peroxidases. The major functions of Prx comprise modulation of signalling cascades that apply hydrogen peroxide (H(2)O(2)) and cellular protection against oxidative stress. Nothing is known about Prx isoforms in human myocardium. We investigated the protein expression of Prx isoforms 1-6 in human non-failing (NF, donor hearts, n=6, male, age: 53.3+/-2.1 years) and failing myocardium (DCM, orthotopic heart transplantation, dilated cardiomyopathy, n=15, male, 57.0+/-1.7 years). In addition, we performed immunohistochemical stainings and measured Prx 4 mRNA expression levels (RNAse protection assay). The protein expression of Prx 1-2 was similar in NF and DCM. The protein expression of Prx 3-6 and the mRNA-expression of Prx 4 were decreased in DCM. Immunohistochemical analyses provided evidence that all Prx isoforms are present in cardiomyocytes and endothelial cells. Whereas Prx 1-5 staining was more pronounced in endothelial cells, Prx6 staining was more evident in cardiomyocytes. This study provides evidence that Prx are differentially regulated in DCM. The selective downregulation of peroxiredoxin 3-6 isoforms may point towards a subcellular specific dysregulation of the antioxidative defence during the development of DCM.     

Temperature dependence of erythromelalgia mutation L858F in sodium channel Nav1.7

Background

The disabling chronic pain syndrome erythromelalgia (also termed erythermalgia) is characterized by attacks of burning pain in the extremities induced by warmth. Pharmacological treatment is often ineffective, but the pain can be alleviated by cooling of the limbs. Inherited erythromelalgia has recently been linked to mutations in the gene SCN9A, which encodes the voltage-gated sodium channel Nav1.7. Nav1.7 is preferentially expressed in most nociceptive DRG neurons and in sympathetic ganglion neurons. It has recently been shown that several disease-causing erythromelalgia mutations alter channel-gating behavior in a manner that increases DRG neuron excitability.

Results

Here we tested the effects of temperature on gating properties of wild type Nav1.7 and mutant L858F channels. Whole-cell voltage-clamp measurements on wild type or L858F channels expressed in HEK293 cells revealed that cooling decreases current density, slows deactivation and increases ramp currents for both mutant and wild type channels. However, cooling differentially shifts the midpoint of steady-state activation in a depolarizing direction for L858F but not for wild type channels.

Conclusion

The cooling-dependent shift of the activation midpoint of L858F to more positive potentials brings the threshold of activation of the mutant channels closer to that of wild type Nav1.7 at lower temperatures, and is likely to contribute to the alleviation of painful symptoms upon cooling in affected limbs in patients with this erythromelalgia mutation.

     

Rapid control of protein level in the apicomplexan Toxoplasma gondii

Analysis of gene function in apicomplexan parasites is limited by the absence of reverse genetic tools that allow easy and rapid modulation of protein levels. The fusion of a ligand-controlled destabilization domain (ddFKBP) to a protein of interest enables rapid and reversible protein stabilization in T. gondii. This allows an efficient functional analysis of proteins that have a dual role during host cell invasion and/or intracellular growth of the parasite.     

Variation among wheat (Triticum easativum L.) genotypes in response to the drought stress: I – selection approaches

The agronomic and physiological traits, drought tolerance indexes, principal component analysis and Ward`s method were applied to assess the differences among 20 wheat genotypes in response to drought. Statistically significant correlation was observed for measured traits. Drought susceptibility index (DSI), stress tolerance index (STI) and stress index (SI) were most useful to identify genotypes differing in their response to drought. Utility of the indexes was confirmed by physiological markers of drought tolerance i.e. membrane injury and leaf water status. Variation of the genotypes in biomass and grain yield during drought stress was also verified by clustering methods. Finally, integration of physiological and statistical methods presented in this work, allows to both, indicate that tolerance to drought in wheat has a common genetic background, and select the most diverse genotypes. Based on the results, we recommend a tool for breeders, useful to select the genotypes resistant and sensitive to drought.

Abbreviations: DM: dry matter; DSI: drought susceptibility index; FWC: field water capacity; GY: grain yield; GMP: geometric mean productivity index; H: plant height; LI: leakage index related to membrane injury; M_PRO: mean productivity index; M_HAR: harmonic mean index; NoT: number of tillers; NoG, W-1000: number of grains and weight of 1000 grains, respectively; NoL_MT, NoL_AT, NoL_T: number of leaves on main tiller, adventitious tillers and total leaf number, respectively; PCA: principal component analysis; RTC: relative trait change; RWC, RT, WD: relative water content, relative turgidity and water deficit, respectively SI: stress index; SPAD: leaf greening; STI: stress tolerance index; TI: tolerance index; WCA: Ward`s cluster analysis.     

A transferable plasticity region in Campylobacter coli allows isolates of an otherwise non‐glycolytic food‐borne pathogen to catabolize glucose

Thermophilic Campylobacter species colonize the intestine of agricultural and domestic animals commensally but cause severe gastroenteritis in humans. In contrast to other enteropathogenic bacteria, Campylobacter has been considered to be non‐glycolytic, a metabolic property originally used for their taxonomic classification. Contrary to this dogma, we demonstrate that several Campylobacter coli strains are able to utilize glucose as a growth substrate. Isotopologue profiling experiments with ¹³C‐labeled glucose suggested that these strains catabolize glucose via the pentose phosphate and Entner‐Doudoroff (ED) pathways and use glucose efficiently for de novo synthesis of amino acids and cell surface carbohydrates. Whole genome sequencing of glycolytic C. coli isolates identified a genomic island located within a ribosomal RNA gene cluster that encodes for all ED pathway enzymes and a glucose permease. We could show in vitro that a non‐glycolytic C. coli strain could acquire glycolytic activity through natural transformation with chromosomal DNA of C. coli and C. jejuni subsp. doylei strains possessing the ED pathway encoding plasticity region. These results reveal for the first time the ability of a Campylobacter species to catabolize glucose and provide new insights into how genetic macrodiversity through intra‐ and interspecies gene transfer expand the metabolic capacity of this food‐borne pathogen.     

A case for more curiosity-driven basic research

Having been selected to be among the exquisitely talented scientists who won the Sandra K. Masur Senior Leadership Award is a tremendous honor. I would like to take this opportunity to make the case for a conviction of mine that I think many will consider outdated. I am convinced that we need more curiosity-driven basic research aimed at understanding the principles governing life. The reasons are simple: 1) we need to learn more about the world around us; and 2) a robust and diverse basic research enterprise will bring ideas and approaches essential for developing new medicines and improving the lives of humankind.When I was a graduate student, curiosity-driven basic research ruled. Studying mating-type switching in budding yeast, for example, was exciting because it was an interesting problem: How can you make two different cells from a single cell in the absence of any external cues? We did not have to justify why it is important to study what many would now consider a baroque question. Scientists and funding agencies alike agreed that this was an exciting biological problem that needed to be solved. I am certain that all scientists of my generation can come up with similar examples.Open in a separate windowAngelika AmonSince the time I was a graduate student, the field of biological research has experienced a revolution. We can now determine the genetic makeup of every species in a week or so and have an unprecedented ability to manipulate any genome. This revolution has led to a sense that we understand the principles governing life and that it is now time to apply this knowledge to cure diseases and make the world a better place. While applying knowledge to improve lives and treat diseases is certainly a worthwhile endeavor, it is important to realize that we are far from having a mechanistic understanding of even the basic principles of biology. What the genomic revolution brought us are lists, some better than others. We now know how many coding genes define a given species and how many protein kinases, GTPases, and so forth there are in the various genomes we sequenced. This knowledge, however, does not even scratch the surface of understanding their function. When I browse the Saccharomyces cerevisiae genome database (my second-favorite website), I am still amazed how many genes there are that have not even been given a name.To me the most important achievement the new genome-sequencing and genome-editing technologies brought us is that nearly every organism can be a model organism now. We can study and manipulate the processes that most fascinate us in the organisms in which they occur, with the exception, of course, of humans. Thus, I believe that the golden era of basic biological research is not behind us but in front of us, and we need more people who will take advantage of the tools that have been developed in the past three decades. I am therefore hoping that many young people will chose a career in basic research and find an exciting question to study. The more of us there are, the more knowledge we will acquire, and the higher the likelihood we will discover something amazing and important. There is so much interesting biology out there that we should strive to understand. Some of my favorite unanswered questions are: What are the biological principles underlying symbiosis and how did it evolve? Why is sleep essential? Why do plants, despite an enormous regenerative potential, never die of cancer? Why do brown bears, despite inactivity, obesity, and high levels of cholesterol, exhibit no signs of atherosclerosis? How do sharks continuously produce teeth?One could, of course, argue that the knowledge we have accumulated over the past 50 years provides a reasonable framework, and it is now time to leave basic science and model organisms behind and focus on what matters—curing diseases, developing methods to produce energy, cleaning up the oceans, preventing global warming, building biological computers, designing organisms, or engineering whatever the current buzz is about. Like David Botstein, who eloquently discussed the importance of basic research in these pages in 2012 (Botstein, 2012 ), I believe that the notion that we already know enough is wrong and the current application-centric view of biology is misguided. Experience has taught us over and over that we cannot predict where the next important breakthrough will be emerge. Many of the discoveries that we consider groundbreaking and that have brought us new medicines or improved our lives in other ways are the result of curiosity-driven basic research. My favorite example is the discovery of penicillin. Alexander Fleming, through the careful study of his (contaminated) bacterial plates, enabled humankind to escape natural selection. More recent success stories such as new cures for hepatitis C, the human papillomavirus vaccine, the HIV-containment regimens, or treatments for BCR-ABL induced chronic myelogenous leukemia have also only been possible because of decades of basic research in model organisms that taught us the principles of life and enabled us to acquire the methodologies critical to develop these treatments. Although work from my own lab on the causes and consequences of chromosome mis-segregation in budding yeast has not led to the development of new treatments, it has taught us a lot about how an imbalanced karyotype, a hallmark of cancer, affects the physiology of cancer cells and creates vulnerabilities in cancer cells that could represent new therapeutic targets.These are but a few examples for why it is important that we scientists must dedicate ourselves to the pursuit of basic knowledge and why we as a society must make funding basic research a priority. Achieving the latter requires that we scientists tell the public about the importance of what we are doing and explain the potential implications of basic research for human health. At the same time, it will be important to manage expectations. We must explain that not every research project will lead to the development of new medicines and that we cannot predict where the next big breakthroughs will materialize. We must further make it clear that this means we have to fund a broad range of basic research at a healthy level. Perhaps a website that collects examples of how basic research has led to breakthroughs in medicine could serve as a showcase for such success stories, bringing the importance of what we do to the public.While conducting research to improve the lives of others is certainly a worthy motivation, it is not the main reason why I get up very early every morning to go to the lab. To me, gaining an understanding of a basic principle in the purest Faustian terms is what I find most rewarding and exciting. Designing and conducting experiments, pondering the results, and developing hypotheses as to how something may work is most exciting, the idea that I, or nowadays the people in my lab, may be (hopefully) the first to discover a new aspect of biology is the best feeling. It is these rare eureka moments, when you first realize how a process works or when you discover something that opens up a new research direction, that make up for all the woes and frustrations that come with being an experimental scientist in an expensive discipline.For me, having a career in curiosity-driven basic research has been immensely rewarding. It is my hope that basic research remains one of the pillars of the American scientific enterprise, attracting the brightest young minds for generations to come. We as a community can help to make this a reality by telling people what we do and highlighting the importance of our work to their lives.