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nutrient sensing

Zheng Huimei, Xiaohang Yang, Yongmei Xi
Remarkable advances have been made in recent years in our understanding of the Drosophila fat body and its functions in energy storage, immune response and nutrient sensing. The fat body interplays with other tissues to respond to the physiological needs of the body's growth and coordinates various metabolic processes at different developmental stages and under different environmental conditions. The identification of various conserved genetic functions and signaling pathways relating to the Drosophila fat body may provide clues to lipometabolic disease and other aspects of tissue remodeling in humans...
October 20, 2016: Life Sciences
Verónica María Corrales-Carvajal, Aldo A Faisal, Carlos Ribeiro
Internal states can profoundly alter the behavior of animals. A quantitative understanding of the behavioral changes upon metabolic challenges is key to a mechanistic dissection of how animals maintain nutritional homeostasis. We used an automated video tracking setup to characterize how amino acid and reproductive states interact to shape exploitation and exploration decisions taken by adult Drosophila melanogaster. We find that these two states have specific effects on the decisions to stop at and leave proteinaceous food patches...
October 22, 2016: ELife
Jonathan W Moore, Julian D Olden
Integrating knowledge of environmental degradation, biodiversity change, and ecosystem processes across large spatial scales remains a key challenge to illuminating the resilience of Earth's systems. There is now a growing realization that the manner in which communities will respond to anthropogenic impacts will ultimately control the ecosystem consequences. Here we examine the response of freshwater fishes and their nutrient excretion - a key ecosystem process that can control aquatic productivity - to human land development across the contiguous United States...
October 20, 2016: Global Change Biology
Jumpei F Yamagishi, Nen Saito, Kunihiko Kaneko
As cells grow and divide under a given environment, they become crowded and resources are limited, as seen in bacterial biofilms and multicellular aggregates. These cells often show strong interactions through exchanging chemicals, as evident in quorum sensing, to achieve mutualism and division of labor. Here, to achieve stable division of labor, three characteristics are required. First, isogenous cells differentiate into several types. Second, this aggregate of distinct cell types shows better growth than that of isolated cells without interaction and differentiation, by achieving division of labor...
October 2016: PLoS Computational Biology
Isabella Bertani, Cara E Steger, Daniel R Obenour, Gary L Fahnenstiel, Thomas B Bridgeman, Thomas H Johengen, Michael J Sayers, Robert A Shuchman, Donald Scavia
Cyanobacteria blooms are a major environmental issue worldwide. Our understanding of the biophysical processes driving cyanobacterial proliferation and the ability to develop predictive models that inform resource managers and policy makers rely upon the accurate characterization of bloom dynamics. Models quantifying relationships between bloom severity and environmental drivers are often calibrated to an individual set of bloom observations, and few studies have assessed whether differences among observing platforms could lead to contrasting results in terms of relevant bloom predictors and their estimated influence on bloom severity...
October 12, 2016: Science of the Total Environment
Helena de Fatima Magliarelli, Mariette Matondo, Gergő Mészáros, Alexander Goginashvili, Eric Erbs, Zhirong Zhang, Michael Mihlan, Christian Wolfrum, Ruedi Aebersold, Izabela Sumara, Romeo Ricci
Adaptation to changes in nutrient availability is crucial for cells and organisms. Posttranslational modifications of signaling proteins are very dynamic and are therefore key to promptly respond to nutrient deprivation or overload. Herein we screened for ubiquitylation of proteins in the livers of fasted and refed mice using a comprehensive systemic proteomic approach. Among 1641 identified proteins, 117 were differentially ubiquitylated upon fasting or refeeding. Endoplasmic reticulum (ER) and secretory proteins were enriched in the livers of refed mice in part owing to an ER-stress-mediated response engaging retro-translocation and ubiquitylation of proteins from the ER...
October 13, 2016: Cell Death & Disease
Jodi L Brewster, James L O McKellar, Thomas J Finn, Janet Newman, Thomas S Peat, Monica L Gerth
Chemoreceptors enable bacteria to detect chemical signals in the environment and navigate towards niches that are favourable for survival. The sensor domains of chemoreceptors function as the input modules for chemotaxis systems, and provide sensory specificity by binding specific ligands. Cache-like domains are the most common extracellular sensor module in prokaryotes, however only a handful have been functionally or structurally characterised. Here, we have characterised a chemoreceptor Cache-like sensor domain (PscD-SD) from the plant pathogen Pseudomonas syringae pv...
October 13, 2016: Scientific Reports
Nathan D Schwalm, Guy E Townsend, Eduardo A Groisman
: The utilization of simple sugars is widespread across all domains of life. In contrast, the breakdown of complex carbohydrates is restricted to a subset of organisms. A regulatory paradigm for integration of complex polysaccharide breakdown with simple sugar utilization was established in the mammalian gut symbiont Bacteroides thetaiotaomicron, whereby sensing of monomeric fructose regulates catabolism of both fructose and polymeric fructans. We now report that a different regulatory paradigm governs utilization of monomeric arabinose and the arabinose polymer arabinan...
October 11, 2016: MBio
Kaitlin M Laws, Daniela Drummond-Barbosa
Multiple aspects of organismal physiology influence the number and activity of stem cells and their progeny, including nutritional status. Previous studies demonstrated that Drosophila germline stem cells (GSCs), follicle stem cells (FSCs), and their progeny sense and respond to diet via complex mechanisms involving many systemic and local signals. AMP-activated protein kinase, or AMPK, is a highly conserved regulator of energy homeostasis known to be activated under low cellular energy conditions; however, its role in the ovarian response to diet has not been investigated...
October 8, 2016: Developmental Biology
Herman Waldmann, Duncan Howie, Stephen Cobbold
A major goal of immunosuppressive therapies is to harness immune tolerance mechanisms so as to minimize unwanted side effects associated with protracted immunosuppressive therapy. Antibody blockade of lymphocyte coreceptor and costimulatory pathways in mice has demonstrated the principle that both naive and primed immune systems can be reprogrammed toward immunological tolerance. Such tolerance can involve the amplification of activity of regulatory T cells, and is maintained through continuous recruitment of such cells through processes of infectious tolerance...
August 2016: Microbiology Spectrum
Arne N Akbar, Sian M Henson, Alessio Lanna
As humans live longer, a central concern is to find ways to maintain their health as they age. Immunity declines during ageing, as shown by the increased susceptibility to infection by both previously encountered and new pathogens and by the decreased efficacy of vaccination. It is therefore crucial to understand the mechanisms responsible for this decrease in immunity and to develop new strategies to enhance immune function in older humans. We discuss here how the induction of senescence alters leukocyte, and specifically T cell, function...
October 3, 2016: Trends in Immunology
Gokhlesh Kumar, Karin Hummel, Maike Ahrens, Simon Menanteau-Ledouble, Timothy J Welch, Martin Eisenacher, Ebrahim Razzazi-Fazeli, Mansour El-Matbouli
Yersinia ruckeri is the causative agent of enteric redmouth disease of fish that causes significant economic losses, particularly in salmonids. Bacterial pathogens differentially express proteins in the host during the infection process, and under certain environmental conditions. Iron is an essential nutrient for many cellular processes and is involved in host sensing and virulence regulation in many bacteria. Little is known about proteomics expression of Y. ruckeri in response to iron-limited conditions...
October 6, 2016: Veterinary Research
Kelei Zhao, Xikun Zhou, Wujiao Li, Xiuyue Zhang, Bisong Yue
Bacteria use a cell-cell communication system termed quorum-sensing (QS) to adjust population size by coordinating the costly but beneficial cooperative behaviors. It has long been suggested that bacterial social conflict for expensive extracellular products may drive QS divergence and cause the "tragedy of the commons". However, the underlying molecular mechanism of social divergence and its evolutionary consequences for the bacterial ecology still remain largely unknown. By using the model bacterium Pseudomonas aeruginosa PAO1, here we show that nutrient reduction can promote QS divergence for population fitness during evolution but requiring adequate cell density...
October 7, 2016: Scientific Reports
Cara C Schafer, Yong Wang, Kenneth P Hough, Anandi Sawant, Stefan C Grant, Victor J Thannickal, Jaroslaw Zmijewski, Selvarangan Ponnazhagan, Jessy S Deshane
Indoleamine 2,3-dioxygenase (IDO) has been implicated in immune evasion by tumors. Upregulation of this tryptophan (Trp)-catabolizing enzyme, in tumor cells and myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment (TME), leads to Trp depletion that impairs cytotoxic T cell responses and survival; however, exact mechanisms remain incompletely understood. We previously reported that a combination therapy of gemcitabine and a superoxide dismutase mimetic promotes anti-tumor immunity in a mouse model of lung cancer by inhibiting MDSCs, enhancing polyfunctional response of CD8+ memory T cells, and extending survival...
September 26, 2016: Oncotarget
A Parmigiani, A V Budanov
Sestrins are a family of stress-responsive genes that have evolved to attenuate damage induced by stress caused to the cell. By virtue of their antioxidant activity, protein products of Sestrin genes prevent the accumulation of reactive oxygen species within the cell, thereby attenuating the detrimental effects of oxidative stress. In parallel, Sestrins participate in several signaling pathways that control the activity of the target of rapamycin protein kinase (TOR). TOR is a crucial sensor of intracellular and extracellular conditions that promotes cell growth and anabolism when nutrients and growth factors are abundant...
2016: International Review of Cell and Molecular Biology
Arne N Akbar
Immunosurveillance requires the migration of lymphocytes and their activation to induce proliferation and effector function. Effective immunity requires an optimal supply of nutrients to lymphocytes. Cells contain nutrient sensing apparatus such as adenosine 5'-monophosphate-activated protein kinase (AMPK) that survey intracellular ATP levels. Immunity declines during ageing and one possibility is that the energy balance may be altered in old lymphocytes. This article summarizes recent data identifying a convergence of senescence and nutrient signalling pathways in lymphocytes that inhibit both T cell and NK cell function during ageing...
September 30, 2016: Clinical and Experimental Immunology
Liufeng Zheng, Wei Zhang, Yuanfei Zhou, Fengna Li, Hongkui Wei, Jian Peng
The mammalian target of rapamycin (mTOR) is the central regulator of mammalian cell growth, and is essential for the formation of two structurally and functionally distinct complexes: mTORC1 and mTORC2. mTORC1 can sense multiple cues such as nutrients, energy status, growth factors and hormones to control cell growth and proliferation, angiogenesis, autophagy, and metabolism. As one of the key environmental stimuli, amino acids (AAs), especially leucine, glutamine and arginine, play a crucial role in mTORC1 activation, but where and how AAs are sensed and signal to mTORC1 are not fully understood...
2016: International Journal of Molecular Sciences
E Fatsini, R Bautista, M Manchado, N J Duncan
The aims of this study were the characterization of the upper olfactory epithelium of cultured and wild Senegalese sole mature males at histological and transcriptomic (using RNA-Seq) level. No significant differences in tissue structure, cell types and cellular distribution pattern (olfactory sensory neurons) were identified between cultured and wild specimens. Deep transcriptomic analysis showed 2387 transcripts were differentially expressed between cultured and wild groups. A detailed analysis identified the differentially expressed transcripts included some olfactory receptors (OR, TAAR and V2R-like) and transcripts related with the control of reproduction such as the brain aromatase cytochrome P450 and tachykinin-3...
September 20, 2016: Comparative Biochemistry and Physiology. Part D, Genomics & Proteomics
Jessica Walls, Linda Sinclair, David Finlay
Most cells in the body have a constant supply of nutrients, which are required to sustain cellular metabolism and functions. In contrast, cells of the immune system can encounter conditions with a limited nutrient supply during the course of an immune response. Cells of the immune system frequently operate in complex nutrient restricted microenvironments such as tumour or inflammatory sites. The concentrations of key nutrients such as glucose and certain amino acids, can be low at these sites, and this can have an impact upon immune cell function...
September 24, 2016: Seminars in Immunology
Gérard Manière, Anna B Ziegler, Flore Geillon, David E Featherstone, Yael Grosjean
Dietary leucine has been suspected to play an important role in insulin release, a hormone that controls satiety and metabolism. The mechanism by which insulin-producing cells (IPCs) sense leucine and regulate insulin secretion is still poorly understood. In Drosophila, insulin-like peptides (DILP2 and DILP5) are produced by brain IPCs and are released in the hemolymph after leucine ingestion. Using Ca(2+)-imaging and ex vivo cultured larval brains, we demonstrate that IPCs can directly sense extracellular leucine levels via minidiscs (MND), a leucine transporter...
September 27, 2016: Cell Reports
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