SIRT1 in astrocytes regulates glucose metabolism and reproductive function

Sirtuin 1 (Sirt1) is an NAD-dependent class III deacetylase that functions as a cellular energy sensor. In addition to its well-characterized effects in peripheral tissues, evidence suggests that SIRT1 in neurons plays a role in the central regulation of energy balance and reproduction, but no studies have addressed the contribution of astrocytes. We show here that overexpression of SIRT1 in astrocytes causes markedly increased food intake, body weight gain, and glucose intolerance, but expression of a deacetylase-deficient SIRT1 mutant decreases food intake and body weight and improves glucose tolerance, particularly in female mice. Paradoxically, the effect of these SIRT1 mutants on insulin tolerance was reversed, with overexpression showing greater insulin sensitivity. The mice overexpressing SIRT1 were more active, generated more heat, and had elevated oxygen consumption, possibly in compensation for the increased food intake. The female overexpressing mice were also more sensitive to diet-induced obesity. Reproductively, the mice expressing the deacetylase-deficient SIRT1 mutant had impaired estrous cycles, decreased LH surges, and fewer corpora lutea, indicating decreased ovulation. The GnRH neurons were responsive to kisspeptin stimulation, but hypothalamic expression of Kiss1 was reduced in the mutant mice. Our results showed that SIRT1 signaling in astrocytes can contribute to metabolic and reproductive regulation independent of SIRT1 effects in neurons.Fil: Choi, Irene. VA San Diego Healthcare System; Estados UnidosFil: Rickert, Emily. University of California at San Diego; Estados UnidosFil: Fernandez, Marina Olga. University of California at San Diego; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Webster, Nicholas J.G.. VA San Diego Healthcare System; Estados Unidos. University of California at San Diego; Estados Unido

Silicon photonic label free biosensors with coherent readout

Silicon photonics enables sensitive and label-free optical biosensors for the detection of chemical and biological substances. Different sensing architectures have been used to improve the limit of detection and increase the dynamic range response. Here, we show experimental limit of detection at state-of-the-art level using silicon nitride integrated Mach-Zehnder interferometers with coherent read-out. These preliminary results are concordant with theoretical results, showing that the proposed approach enables the use of simple read-out equipment using low-cost laser sources

Neuronal SIRT1 regulates metabolic and reproductive function and the response to caloric restriction

Sirt1 is a NAD-dependent class III deacetylase that functions as a cellular energy sensor. In addition to its well-characterized effects in peripheral tissues, emerging evidence suggests that neuronal Sirt1 activity plays a role in the central regulation of energy balance and glucose metabolism. In this study we generated mice expressing an enzymatically inactive form (NMUT) or wild-type SIRT1 (N-OX) in mature neurons. Both N-OX male and female mice showed impaired glucose tolerance, and N-MUT female, but not male, mice showed improvedglucose tolerance compared to WT littermates. Furthermore, all mice showed improved glucose tolerance with caloric restriction (CR), but the N-OX mice showed the greatest change and now showed better glucose tolerance than their littermates. At the reproductive level, N-OX females showed impaired estrous cycles, with increased cycle length and more time in estrus. LH andprogesterone surges were absent on the evening of proestrus in the N-OX mice suggesting a defect in spontaneous ovulation, which was confirmed by the ovarian histology with a reduced number of corpora lutea. Despite this defect, the mice were still fertile when mated to wild-type mice on the day of pro-estrus indicating that the mice can respond to normal pheromonal or environmental cues. When subjected to CR, the N-OX mice went into diestrus arrest earlier than their littermates. Together, these results suggested that the overexpression of SIRT1 rendered the mice more sensitive to the metabolic improvements and suppression of reproductive cycles by CR, which was independent of circadian rhythms.Fil: Rickert, Emily. University of California at San Diego; Estados Unidos. VA San Diego Healthcare System; Estados UnidosFil: Fernandez, Marina Olga. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. University of California at San Diego; Estados UnidosFil: Gorman, Michael. University of California at San Diego; Estados UnidosFil: Olefsky, Jerrold M.. University of California at San Diego; Estados UnidosFil: Webster, Nicholas J.G.. Va San Diego Healthcare System; Estados Unidos. University of California at San Diego; Estados Unido

Jurassic: A chemically anomalous structure in the Galactic halo

Indexación ScopusDetailed elemental-abundance patterns of giant stars in the Galactic halo measured by the Apache Point Observatory Galactic Evolution Experiment (APOGEE-2) have revealed the existence of a unique and significant stellar subpopulation of silicon-enhanced ([Si/Fe] ≳ +0.5) metal-poor stars, spanning a wide range of metallicities (-1.5 ≲ [Fe/H] ≲-0.8). Stars with over-abundances in [Si/Fe] are of great interest because these have very strong silicon (28Si) spectral features for stars of their metallicity and evolutionary stage, offering clues about rare nucleosynthetic pathways in globular clusters (GCs). Si-rich field stars have been conjectured to have been evaporated from GCs, however, the origin of their abundances remains unclear, and several scenarios have been offered to explain the anomalous abundance ratios. These include the hypothesis that some of them were born from a cloud of gas previously polluted by a progenitor that underwent a specific and peculiar nucleosynthesis event or, alternatively, that they were due to mass transfer from a previous evolved companion. However, those scenarios do not simultaneously explain the wide gamut of chemical species that are found in Si-rich stars. Instead, we show that the present inventory of such unusual stars, as well as their relation to known halo substructures (including the in situ halo, Gaia-Enceladus, the Helmi Stream(s), and Sequoia, among others), is still incomplete. We report the chemical abundances of the iron-peak (Fe), the light-(C and N), the α-(O and Mg), the odd-Z (Na and Al), and the s-process (Ce and Nd) elements of 55 newly identified Si-rich field stars (among more than ∼600 000 APOGEE-2 targets), which exhibit over-abundances of [Si/Fe] as extreme as those observed in some Galactic GCs, and they are relatively well distinguished from other stars in the [Si/Fe]-[Fe/H] plane. This new census confirms the presence of a statistically significant and chemically-anomalous structure in the inner halo: Jurassic. The chemo-dynamical properties of the Jurassic structure is consistent with it being the tidally disrupted remains of GCs, which are easily distinguished by an over-abundance of [Si/Fe] among Milky Way populations or satellites. © J. G. Fernandez-Trincado et al. 2020.https://www.aanda.org/articles/aa/full_html/2020/12/aa39434-20/aa39434-20.htm

The Caveolin-1 Connection to Cell Death and Survival

Nunez, S (Nunez, S.)[ 1,4 ] 1. Fac Med, CEMC, Lab Comunicac Celulares, Santiago, Chile. 4. Univ Talca, Fac Hlth Sci, Talca, ChileCaveolins are a family of membrane proteins required for the formation of small plasma membrane invaginations called caveolae that are implicated in cellular trafficking processes. In addition to this structural role, these scaffolding proteins modulate numerous intracellular signaling pathways; often via direct interaction with specific binding partners. Caveolin-1 is particularly well-studied in this respect and has been attributed a large variety of functions. Thus, Caveolin-1 also represents the best-characterized isoform of this family with respect to its participation in cancer. Rather strikingly, available evidence indicates that Caveolin-1 belongs to a select group of proteins that function, depending on the cellular settings, both as tumor suppressor and promoter of cellular traits commonly associated with enhanced malignant behavior, such as metastasis and multi-drug resistance. The mechanisms underlying such ambiguity in Caveolin-1 function constitute an area of great interest. Here, we will focus on discussing how Caveolin-1 modulates cell death and survival pathways and how this may contribute to a better understanding of the ambiguous role this protein plays in cancer

Analysis of Process Configurations for CO2 Capture by Precipitating Amino Acid Solvents

Precipitating amino acid solvents are an alternative to conventional amine scrubbing for CO2 capture from flue gas. Process operation with these solvents leads to the formation of precipitates during absorption that need to be re-dissolved prior to desorption of CO2. The process configuration is crucial for the successful application of these solvents. Different process configurations have been analyzed in this work, including a full analysis of the baseline operating conditions (based on potassium taurate), the addition of lean vapor compression, multiple absorber feeds, and the use of different amino acids as alternative solvents to the baseline based on potassium taurate. The analysis is carried out with an equilibrium model of the process that approximates the thermodynamics of the solvents considered. The results show that the precipitating amino acid solvents can reduce the reboiler duty needed to regenerate the solvent with respect to a conventional MEA process. However, this reduction is accompanied by an expenditure in lower grade energy needed to dissolve the precipitates. To successfully implement these processes into power plants, an internal recycle of the rich stream is necessary. This configuration, known as DECAB Plus, can lower the overall energy use of the capture process, which includes the energy needed to regenerate the solvent, the energy needed to dissolve the precipitates, and the energy needed to compress the CO2 to 110 bar. With respect to the energy efficiency, the DECAB Plus with lean vapor compression configuration is the best configuration based on potassium taurate, which reduces the reboiler duty for regeneration by 45% with respect to conventional MEA. Retrofitting this process into a coal fired power plant will result in overall energy savings of 15% with respect to the conventional MEA process, including compression of the CO2 stream to 110 bar. Potassium alanate was found to reduce the energy use with respect to potassium taurate under similar process configurations. Therefore, the investigation of potassium alanate in a DECAB Plus configuration is highly recommended, since it can reduce the energy requirements of the best process configuration based on potassium taurat

Finite temperature theory of the trapped two dimensional Bose gas

We present a Hartree-Fock-Bogoliubov (HFB) theoretical treatment of the two-dimensional trapped Bose gas and indicate how semiclassical approximations to this and other formalisms have lead to confusion. We numerically obtain results for the fully quantum mechanical HFB theory within the Popov approximation and show that the presence of the trap stabilizes the condensate against long wavelength fluctuations. These results are used to show where phase fluctuations lead to the formation of a quasicondensate.Comment: 4 pages, 3 figure

Sensors based on polymer modified electrodes

This paper will review the recent results that we have obtained using novel ruthenium-containing polymers, and on the further studies on the incorporation of proteins into polymeric matrices