scholarly journals Galactose metabolic genes in yeast respond to a ratio of galactose and glucose

2015 ◽  
Vol 112 (5) ◽  
pp. 1636-1641 ◽  
Author(s):  
Renan Escalante-Chong ◽  
Yonatan Savir ◽  
Sean M. Carroll ◽  
John B. Ingraham ◽  
Jue Wang ◽  
...  
Keyword(s):  
Classical Model ◽  
Nutrient Sensing ◽  
Natural Environments ◽  
Glucose Signaling ◽  
Glucose Levels ◽  
Metabolic Genes ◽  
Wide Range ◽  
Controlled Environments ◽  
Single Input ◽  
Gal Genes

Natural environments are filled with multiple, often competing, signals. In contrast, biological systems are often studied in “well-controlled” environments where only a single input is varied, potentially missing important interactions between signals. Catabolite repression of galactose by glucose is one of the best-studied eukaryotic signal integration systems. In this system, it is believed that galactose metabolic (GAL) genes are induced only when glucose levels drop below a threshold. In contrast, we show that GAL gene induction occurs at a constant external galactose:glucose ratio across a wide range of sugar concentrations. We systematically perturbed the components of the canonical galactose/glucose signaling pathways and found that these components do not account for ratio sensing. Instead we provide evidence that ratio sensing occurs upstream of the canonical signaling pathway and results from the competitive binding of the two sugars to hexose transporters. We show that a mutant that behaves as the classical model expects (i.e., cannot use galactose above a glucose threshold) has a fitness disadvantage compared with wild type. A number of common biological signaling motifs can give rise to ratio sensing, typically through negative interactions between opposing signaling molecules. We therefore suspect that this previously unidentified nutrient sensing paradigm may be common and overlooked in biology.

scholarly journals Timing it right: The Measurement and Prediction of Flowering

2002 ◽  
pp. 17-22
Author(s):  
R. J. Summerfiled
Keyword(s):  
Photoperiod Sensitivity ◽  
Natural Environments ◽  
Considerable Evidence ◽  
Germplasm Collections ◽  
Physiological Stage ◽  
Wide Range ◽  
Flowering Behaviour ◽  
Controlled Environments ◽  
Biochemical Mechanisms ◽  
Temperature Responses

Although the model described here was developed from research in controlled environments, there is now considerable evidence that in can be applied to a very wide range of natural environments in several species. Multi-locational trials augmented by successional sowing and, if considered necessary, supplementary illumination in the field to increase daylength, can be used to estimate the values of the model coefficients: (1) to characterize germplasm collections and so predict flowering behaviour elsewhere; (2) for interpreting and understanding crop adaptation; and (3) for genetic analysis of photoperiod sensitivity. We do not yet know whether the model has any contribution to make to the understanding of the biochemical mechanisms of photoperiod and temperature responses, but at the very least, it should provide the basis for indicating the most appropriate environmental conditions, genotypes and physiological stage of the plants most suitable for such investigations.

Novel Loci Control Variation in Reproductive Timing inArabidopsis thalianain Natural Environments

Genetics ◽  
2002 ◽  
Vol 162 (4) ◽  
pp. 1875-1884 ◽  
Author(s):  
Cynthia Weinig ◽  
Mark C Ungerer ◽  
Lisa A Dorn ◽  
Nolan C Kane ◽  
Yuko Toyonaga ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Allelic Variation ◽  
Developmental Pathways ◽  
Natural Environments ◽  
Reproductive Timing ◽  
Controlled Environments ◽  
Photoperiod Pathway ◽  
Differential Involvement ◽  
Short Days ◽  
Transition To Flowering

AbstractMolecular biologists are rapidly characterizing the genetic basis of flowering in model species such as Arabidopsis thaliana. However, it is not clear how the developmental pathways identified in controlled environments contribute to variation in reproductive timing in natural ecological settings. Here we report the first study of quantitative trait loci (QTL) for date of bolting (the transition from vegetative to reproductive growth) in A. thaliana in natural seasonal field environments and compare the results with those obtained under typical growth-chamber conditions. Two QTL specific to long days in the chamber were expressed only in spring-germinating cohorts in the field, and two loci specific to short days in the chamber were expressed only in fall-germinating cohorts, suggesting differential involvement of the photoperiod pathway in different seasonal environments. However, several other photoperiod-specific QTL with large effects in controlled conditions were undetectable in natural environments, indicating that expression of allelic variation at these loci was overridden by environmental factors specific to the field. Moreover, a substantial number of QTL with major effects on bolting date in one or more field environments were undetectable under controlled environment conditions. These novel loci suggest the involvement of additional genes in the transition to flowering under ecologically relevant conditions.

scholarly journals Role of Insulin in Health and Disease: An Update

2021 ◽  
Vol 22 (12) ◽  
pp. 6403
Author(s):  
Md Saidur Rahman ◽  
Khandkar Shaharina Hossain ◽  
Sharnali Das ◽  
Sushmita Kundu ◽  
Elikanah Olusayo Adegoke ◽  
...  
Keyword(s):  
Insulin Signaling ◽  
Basic Research ◽  
Future Research ◽  
Protective Effects ◽  
Glucose Levels ◽  
Physiological Processes ◽  
Blood Glucose Levels ◽  
Wide Range ◽  
Health And Disease

Insulin is a polypeptide hormone mainly secreted by β cells in the islets of Langerhans of the pancreas. The hormone potentially coordinates with glucagon to modulate blood glucose levels; insulin acts via an anabolic pathway, while glucagon performs catabolic functions. Insulin regulates glucose levels in the bloodstream and induces glucose storage in the liver, muscles, and adipose tissue, resulting in overall weight gain. The modulation of a wide range of physiological processes by insulin makes its synthesis and levels critical in the onset and progression of several chronic diseases. Although clinical and basic research has made significant progress in understanding the role of insulin in several pathophysiological processes, many aspects of these functions have yet to be elucidated. This review provides an update on insulin secretion and regulation, and its physiological roles and functions in different organs and cells, and implications to overall health. We cast light on recent advances in insulin-signaling targeted therapies, the protective effects of insulin signaling activators against disease, and recommendations and directions for future research.

scholarly journals SGLT2 inhibitors: a narrative review of efficacy and safety

2021 ◽  
Vol 121 (2) ◽  
pp. 229-239
Author(s):  
Donald S. Nelinson ◽  
Jose M. Sosa ◽  
Robert J. Chilton
Keyword(s):  
Adverse Events ◽  
Sglt2 Inhibitor ◽  
Sglt2 Inhibitors ◽  
Narrative Review ◽  
Atherosclerotic Cardiovascular Disease ◽  
Comorbid Conditions ◽  
Postprandial Plasma Glucose ◽  
Renal Outcomes ◽  
Glucose Levels ◽  
Wide Range

Abstract Type 2 diabetes mellitus (T2DM) is a cardio-renal-metabolic condition that is frequently associated with multiple comorbidities, including atherosclerotic cardiovascular disease (ASCVD), heart failure (HF), and chronic kidney disease (CKD). The sodium-glucose co-transporter-2 (SGLT2) inhibitors, which lower glycated hemoglobin, fasting and postprandial plasma glucose levels, body weight, and blood pressure, as well as reduce the risk of a range of cardiovascular and renal outcomes without increasing hypoglycaemic risk, have heralded a paradigm shift in the management of T2DM. These drugs are compatible with most other glucose-lowering agents and can be used in patients with a wide range of comorbid conditions, including ASCVD, HF, and CKD, and in those with estimated glomerular filtration rates as low as 30 mL/min/1.73 m2. However, there are misunderstandings surrounding the clinical implications of SGLT2 inhibitors’ mechanism of action and concerns about the key adverse events with which this class of drugs has been associated. This narrative review summarizes the data that support the efficacy of SGLT2 inhibitors in reducing the risks of cardiovascular and renal outcomes in patients with T2DM and comorbid conditions and clarifies information relating to SGLT2 inhibitor-related adverse events.

scholarly journals Real-time gaze estimation via pupil center tracking

2018 ◽  
Vol 9 (1) ◽  
pp. 6-18 ◽  
Author(s):  
Dario Cazzato ◽  
Fabio Dominio ◽  
Roberto Manduchi ◽  
Silvia M. Castro
Keyword(s):  
Real Time ◽  
Learning Algorithm ◽  
Natural Environments ◽  
Gaze Estimation ◽  
Head Pose ◽  
Data Set ◽  
Gaze Tracking ◽  
Illumination Changes ◽  
Wide Range ◽  
Estimation System

Abstract Automatic gaze estimation not based on commercial and expensive eye tracking hardware solutions can enable several applications in the fields of human computer interaction (HCI) and human behavior analysis. It is therefore not surprising that several related techniques and methods have been investigated in recent years. However, very few camera-based systems proposed in the literature are both real-time and robust. In this work, we propose a real-time user-calibration-free gaze estimation system that does not need person-dependent calibration, can deal with illumination changes and head pose variations, and can work with a wide range of distances from the camera. Our solution is based on a 3-D appearance-based method that processes the images from a built-in laptop camera. Real-time performance is obtained by combining head pose information with geometrical eye features to train a machine learning algorithm. Our method has been validated on a data set of images of users in natural environments, and shows promising results. The possibility of a real-time implementation, combined with the good quality of gaze tracking, make this system suitable for various HCI applications.

scholarly journals Exosome-Mediated Insulin Delivery for the Potential Treatment of Diabetes Mellitus

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1870
Author(s):  
Belén Rodríguez-Morales ◽  
Marilena Antunes-Ricardo ◽  
José González-Valdez
Keyword(s):  
Diabetes Mellitus ◽  
Human Insulin ◽  
Insulin Delivery ◽  
Dermal Fibroblasts ◽  
Therapeutic Drug ◽  
Extracellular Medium ◽  
Glucose Levels ◽  
Wide Range ◽  
Diabetes Mellitus Treatment

Exosomes are extracellular nanovesicles between 30 and 150 nm that serve as essential messengers for different biological signaling and pathological processes. After their discovery, a wide range of applications have been developed, especially in therapeutic drug delivery. In this context, the aim of this work was to test the efficiency of exosome-mediated human insulin delivery using exosomes extracted from three different cell lines: hepatocellular carcinoma (HepG2); primary dermal fibroblasts (HDFa) and pancreatic β cells (RIN-m); all are related to the production and/or the ability to sense insulin and to consequently regulate glucose levels in the extracellular medium. The obtained results revealed that the optimal insulin loading efficiency was achieved by a 200 V electroporation, in comparison with incubation at room temperature. Moreover, the maximum in vitro exosome uptake was reached after incubation for 6 h, which slightly decreased 24 h after adding the exosomes. Glucose quantification assays revealed that exosome-mediated incorporation of insulin presented significant differences in HDFa and HepG2 cells, enhancing the transport in HDFa, in comparison with free human insulin effects in the regulation of extracellular glucose levels. No significant differences were found between the treatments in RIN-m cells. Hence, the results suggest that exosomes could potentially become a valuable tool for stable and biocompatible insulin delivery in diabetes mellitus treatment alternatives.

Bacterial extracellular polysaccharides

1988 ◽  
Vol 34 (4) ◽  
pp. 415-420 ◽  
Author(s):  
Chris Whitfield
Keyword(s):  
Pathogenic Bacteria ◽  
Structural Information ◽  
Extracellular Polysaccharides ◽  
Natural Environments ◽  
Chemical Structures ◽  
Technological Advances ◽  
Wide Range ◽  
Surface Polysaccharides ◽  
Surface Location ◽  
Commercial Applications

The synthesis of extracellular polysaccharides has been recognized in certain bacterial cultures since the 1880s. It is now apparent that a wide range of bacteria produce these polymers and an equally wide range of chemical structures are possible. Their surface location, together with the range of available monosaccharide combinations, noncarbohydrate substituents, and linkage types, make extracellular polysaccharides excellent agents of diversity. As a result, much effort has been directed towards elucidating their structure in pathogenic bacteria and in enteric organisms in particular. Commercial applications of microbial polysaccharides have now broadened the scope of structural information. Most recently, technological advances in molecular biology have created the possibility of manipulating desired polymer characteristics, and with these advances, our knowledge of the mechanisms of synthesis and regulation of cell surface polysaccharides has improved. Ultimately more information regarding the function of extracellular polysaccharides in natural environments may result.

T1D Hypoglycemia Prediction Algorithms: A Systematic Review (Preprint)

2021 ◽  
Author(s):  
Stella Tsichlaki ◽  
Lefteris Koumakis ◽  
Manolis Tsiknakis
Keyword(s):  
Type 1 Diabetes ◽  
Blood Glucose ◽  
Digital Libraries ◽  
Predictive Models ◽  
Real Life ◽  
Blood Glucose Monitoring ◽  
Detection Techniques ◽  
Glucose Levels ◽  
Wide Range

BACKGROUND Diabetes is a chronic condition that necessitates regular monitoring and self-management of the patient's blood glucose levels. People with type 1 diabetes (T1D) can live a productive life if they receive proper diabetes care. Nonetheless, a loose glycemic control might increase the risk of developing hypoglycemia. This incident can occur due to a variety of causes, such as taking additional doses of insulin, skipping meals, or over-exercising. Mainly, the symptoms of hypoglycemia range from mild dysphoria to more severe conditions, if not detected in a timely manner. OBJECTIVE In this review, we report on innovative detection techniques and tactics for identifying and preventing hypoglycemic episodes, focusing on type 1 diabetes. METHODS A systematic literature search following the PRISMA guidelines was performed focusing on the “PUBMED”, “Google Scholar”, “IEEE Xplore” and “ACM” digital libraries to find articles about technologies related to hypoglycemia detection in type 1 diabetes patients. RESULTS The presented approaches have been utilized or devised to enhance blood glucose monitoring and boost its efficacy to forecast future glucose levels, which could aid the prediction of future episodes of hypoglycemia. We detected nineteen predictive models for hypoglycemia, specifically on type 1 diabetes, utilizing a wide range of algorithmic methodologies, spanning from statistics (10%) to machine learning (52%) and deep learning (38%). The algorithms employed most are the kalman filtering and classification models (SVM, KNN, random forests). The performance of the predictive models was found overall to be satisfactory, reaching accuracies between 70% and 99% which proves that such technologies are capable to facilitate the prediction of T1D hypoglycemia. CONCLUSIONS It is evident that CGM can improve the glucose control in diabetes but predictive models for hypo- and hyper- glycemia using only mainstream noninvasive sensors such as wristbands and smartwatches are foreseen to be the next step for mHealth in T1D. Prospective studies are required to demonstrate the value of such models in real-life mHealth interventions.

Concluding Speculations

2019 ◽  
pp. 334-344
Author(s):  
Mari Riess Jones
Keyword(s):  
Natural Environments ◽  
Laboratory Studies ◽  
Control Stimulus ◽  
Wide Range ◽  
Stimulus Timing

This final chapter is speculative. It addresses the entrainment assumptions of universality and resonance by reviewing the natural environments of a range of different species, from crickets to whales. The idea is that sensitivity to both rate and rhythm across different species is support for assuming natural driving rhythms exist that facilitate entrainment in a wide range of other species. Also discussed are two artifactual environments experienced by humans: namely, that of laboratory studies that artificially control stimulus timing and the contemporary machine-driven environment of computers and iPhones. The latter are speculated to lead to a sporadic habitat based on fast irregular (artifactual) driving rhythms.

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