Simple and easy to engineer metal-sensing molecules that are capable of differentiating metal ions and producing metal-specific signals are highly desirable. Metal ions affect the thermal stability ...of proteins by increasing or decreasing their resistance to unfolding. This work illustrates a new strategy for designing bivalent fluorescent fusion proteins capable of differentiating metal ions in solution through their distinct effects on a protein’s thermal stability. A new dual purpose metal sensor was developed consisting of biotin protein ligase (BirA) from B. pseudomallei (Bp) fused to green fluorescent protein (GFP). When coupled with differential scanning fluorimetry of GFP-tagged proteins (DSF-GTP) for signal-transduction detection, Bp BirA-GFP yields distinct protein unfolding signatures with Zn(II) and Cu(II) ions in aqueous solutions. The limit of detection of the system is ∼1 μM for both metal species. The system can be used in a variety of high-throughput assay formats including for the screening of metal-binding proteins and chelators. Bp BirA-GFP has also the additional benefit of being useful in Cu(II) ion field-testing applications through simple visual observation of a temperature-dependent loss of fluorescence. Bp BirA-GFP is the first example of a protein-based dual purpose Cu(II) and Zn(II) ion sensor compatible with two different yet complementary signal-transduction detection systems.
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•Burkholderia pseudomallei biotin protein ligase senses copper and zinc ions in water.•GFP-tagged biotin protein ligase differentiates between copper and zinc ions.•The assay format allows high-throughput screening of metal chelating agents.•A simple visual in-field water testing format was devised for copper ion detection.•Recommended maximum impurity concentrations of copper are easily detected in water.
Understanding the intricate relationship between temperature and physiological processes in ectotherm vertebrates is crucial for predicting how these animals respond to environmental changes, ...including those associated with climate change. This is particularly relevant for the anurans, given their limited capacity for thermoregulation, particularly in larval stages. Herein, we investigated the capacity for thermal acclimatization in Thoropa taophora tadpoles, an endemic species in the Atlantic rainforest of Southeast Brazil, inhabiting distinct thermal environments. These semi-terrestrial tadpoles develop on rocky surfaces with some populations inhabiting exposed regions near the marine coast where temperatures may reach up to 30 °C in sunny conditions, while other populations occupy forested areas near waterfalls that maintain lower temperatures. We aimed to understand the effects of temperature on locomotor performance and on the activity of metabolic enzymes that support performance in tadpoles sampled in four different populations. Moreover, we measured several aspects of thermoregulation including the critical thermal maximum (CTmax), the body temperature of activity (Tb), the preferred temperature (Tpref) and the effectiveness of thermoregulation (E). Despite differences in body size, tadpoles from warmer environments consistently demonstrate higher locomotor performance, with minimal or no acclimatization seen in other variables. Correlations between habitat temperature and biological endpoints underscore the significance of maximum locomotor performance in shaping physiological responses. Our results show how temperature can impact tadpole behavior and performance, without change in many organismal measures of thermal acclimatization, providing insights into potential ecological implications, particularly in the context of climate change.
Although individuals of some species appear able to distinguish among individuals of a second species, an alternative explanation is that individuals of the first species may simply be distinguishing ...between familiar and unfamiliar individuals of the second species. In that case, they would not be learning unique characteristics of any given heterospecific, as commonly assumed. Here we show that female Northern Mockingbirds (Mimus polyglottos) can quickly learn to distinguish among different familiar humans, flushing sooner from their nest when approached by people who pose increasingly greater threats. These results demonstrate that a common small songbird has surprising cognitive abilities, which likely facilitated its widespread success in human-dominated habitats. More generally, urban wildlife may be more perceptive of differences among humans than previously imagined.
This article focuses on the determination and the validation of the new Mean Sea Surface from the CNES/CLS. This new model merges multiple satellite altimeters over 16 years of observations. ...Particular attention was paid on the analysis of the oceanic variability. Then a novel method was applied to remove this variability and to take into account different kinds of errors that affect the data. Several types of validations were performed to estimate the quality of the shortest topographic structures and to quantify the accuracy of the mean oceanic content at a larger scale.
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Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Hydrogenation processes leading from biomolecules to fossil biomarkers in anoxic sediments are crucial for the preservation of organic matter. However, these processes are still poorly understood. ...The present identification of several reduced carotenoids in recent sediments attests that these processes operate at the earliest stages of diagenesis without structural or stereochemical specificity, implying a nonbiological reduction pathway. Sulfur species (e.g., H₂S) are the hydrogen donors involved in such reduction, as demonstrated with laboratory experiments. These reactions allow the preservation of abundant organic carbon in the rock record.
From the second part of the 6th millennium BC onwards, pottery manufacture is attested throughout the western Mediterranean. The study of the functional and use of vessels has become a valuable ...source of information on the culinary patterns and subsistence practices of past societies. In the present study, we have analyzed the organic residues of a total of 37 ceramic vessels from the first Neolithic settlements in the Central Pyrenees. Results from lipid analysis using gas chromatography-mass spectrometry (GC–MS) and GC-stable carbon isotope ratio analyses (GC-IRMS) revealed that from the earliest phases, the use of pottery was related to the exploitation of dairy and meat products, as well as plant resources. The data obtained are contextualized within the general frame of the Pyrenees and the western Mediterranean.
The purpose of this study was to determine whether chronic cold exposure would increase the aerobic capacity of skeletal muscle in UCP-dta mice, a transgenic line lacking brown adipose tissue (BAT). ...Wild type and UCP-dta mice were acclimated to either warm (23°C), or cold (4°C) conditions. Cold increased muscle oxidative capacity nearly equivalently in wild-type and UCP-dta mice, but did not affect the respiratory function of isolated mitochondria. Summit metabolism (V˙O2summit) and norepinephrine-induced thermogenesis (V˙O2NST) were significantly lower in UCP-dta mice relative to wild-type mice regardless of temperature treatment, but both were significantly higher in cold relative to warm acclimated mice. BAT mass was significantly higher in the cold relative to warm acclimated wild-type mice, but not in cold acclimated UCP-dta mice. BAT citrate synthase activity was lower in transgenic animals regardless of acclimation temperature and BAT citrate synthase activity per depot was significantly higher only in the cold acclimated wild-type mice. Muscle citrate synthase activity was increased in both genotypes. As defects in muscle oxidative function have been observed with obesity and type 2 diabetes, these results suggest that chronic cold exposure is a useful intervention to drive skeletal muscle oxidative capacity in mouse models of obesity.
Adipose tissue is an active endocrine organ that produces a variety of secretory factors involved in the initiation of angiogenic processes. The bioactive peptide apelin is the endogenous ligand of ...the G protein-coupled receptor, APJ. Here we investigated the potential role of apelin and its receptor, APJ, in the angiogenic responses of human endothelial cells and the development of a functional vascular network in a model of adipose tissue development in mice. Treatment of human umbilical vein endothelial cells with apelin dose-dependently increased angiogenic responses, including endothelial cell migration, proliferation, and Matrigel® capillary tubelike structure formation. These endothelial effects of apelin were due to activation of APJ, because siRNA directed against APJ, which led to long-lasting down-regulation of APJ mRNA, abolished cell migration induced by apelin in contrast to control nonsilencing siRNA. Hypoxia up-regulated the expression of apelin in 3T3F442A adipocytes, and we therefore determined whether apelin could play a role in adipose tissue angiogenesis in vivo. Epididymal white adipose tissue (EWAT) transplantation was performed as a model of adipose tissue angiogenesis. Transplantation led to increased apelin mRNA levels 2 and 5 days after transplantation associated with tissue hypoxia, as evidenced by hydroxyprobe staining on tissue sections. Graft revascularization evolved in parallel, as the first functional vessels in EWAT grafts were observed 2 days after transplantation and a strong angiogenic response was apparent on day 14. This was confirmed by determination of graft hemoglobin levels, which are indicative of functional vascularization and were strongly increased 5 and 14 days after transplantation. The role of apelin in the graft neovascularization was then assessed by local delivery of stable complex apelin-targeting siRNA leading to dramatically reduced apelin mRNA levels and vascularization (quantified by hemogloblin content) in grafted EWAT on day 5 when compared with control siRNA. Taken together, our data provide the first evidence that apelin/APJ signaling pathways play a critical role in the development of the functional vascular network in adipose tissue. In addition, we have shown that adipocyte-derived apelin can be up-regulated by hypoxia. These findings provide novel insights into the complex relationship between adipose tissue and endothelial vascular function and may lead to new therapeutic strategies to modulate angiogenesis.-- Kunduzova, O., Alet, N., Delesque-Touchard, N., Millet, L., Castan-Laurell, I., Muller, C., Dray, C., Schaeffer, P., Herault, J. P., Savi, P., Bono, F., Valet, P. Apelin/APJ signaling system: a potential link between adipose tissue and endothelial angiogenic processes.
Two approaches of ocean color data merging were tested and compared in the North and Equatorial Atlantic Basin: the weighted averaging and the objective analysis. The datasets used were the daily ...level-3 binned data of chlorophyll-a from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer on the Aqua satellite over the year 2003, which is the first common full year of operation. Since they represent input for both approaches, matchups between the satellite and the in situ data from the SeaWiFS Bio-optical Archive and Storage System and the Atlantic Meridional Transect were first studied to compute a spatial map of the root mean-square error and of the bias. Because of the log distribution of the chlorophyll fields, each approach was applied to untransformed and log-transformed values. The application of the weighted averaging to log-transformed values does not show significant differences in comparison to its application to untransformed values. This is not the case, however, for the objective analysis that gives better results when applied to log-transformed values. Both approaches give combined chlorophyll data of equivalent quality, although the objective analysis could be improved with a better statistical characterization of noise and signal covariance. The main advantage of the objective analysis is its ability to interpolate in space (and time) by taking into account the characteristic scales of chlorophyll-a. As a result, the spatial coverage of the combined data is at least twice as large in the case of objective analysis than weighted averaging
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