Unlike most cells of the body which function in an ionic environment controlled within narrow limits, spermatozoa must function in a less controlled external environment. In order to better ...understand how sperm control their membrane potential in different ionic conditions, we measured mouse sperm membrane potentials under a variety of conditions and at different external K(+) concentrations, both before and after capacitation. Experiments were undertaken using both wild-type, and mutant mouse sperm from the knock-out strain of the sperm-specific, pH-sensitive, SLO3 K(+) channel. Membrane voltage data were fit to the Goldman-Hodgkin-Katz equation. Our study revealed a significant membrane permeability to both K(+) and Cl(-) before capacitation, as well as Na(+). The permeability to both K(+) and Cl(-) has the effect of preventing large changes in membrane potential when the extracellular concentration of either ion is changed. Such a mechanism may protect against undesired shifts in membrane potential in changing ionic environments. We found that a significant portion of resting membrane potassium permeability in wild-type sperm was contributed by SLO3 K(+) channels. We also found that further activation of SLO3 channels was the essential mechanism producing membrane hyperpolarization under two separate conditions, 1) elevation of external pH prior to capacitation and 2) capacitating conditions. Both conditions produced a significant membrane hyperpolarization in wild-type which was absent in SLO3 mutant sperm. Hyperpolarization in both conditions may result from activation of SLO3 channels by raising intracellular pH; however, demonstrating that SLO3-dependent hyperpolarization is achieved by an alkaline environment alone shows that SLO3 channel activation might occur independently of other events associated with capacitation. For example sperm may undergo stages of membrane hyperpolarization when reaching alkaline regions of the female genital tract. Significantly, other events associated with sperm capacitation, occur in SLO3 mutant sperm and thus proceed independently of hyperpolarization.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
► We evaluate a method for mapping field-scale evapotranspiration at daily timesteps. ► Interpolation assumes conservation of actual-to-potential ET between imaging dates. ► The method misses ET ...peaks due to irrigation, but reasonably reproduces seasonal ET. ► Further analyses can help to identify optimal characteristics of mapping missions.
Robust spatial information about environmental water use at field scales and daily to seasonal timesteps will benefit many applications in agriculture and water resource management. This information is particularly critical in arid climates where freshwater resources are limited or expensive, and groundwater supplies are being depleted at unsustainable rates to support irrigated agriculture as well as municipal and industrial uses. Gridded evapotranspiration (ET) information at field scales can be obtained periodically using land–surface temperature-based surface energy balance algorithms applied to moderate resolution satellite data from systems like Landsat, which collects thermal-band imagery every 16days at a resolution of approximately 100m. The challenge is in finding methods for interpolating between ET snapshots developed at the time of a clear-sky Landsat overpass to provide complete daily time-series over a growing season. This study examines the efficacy of a simple gap-filling algorithm designed for applications in data-sparse regions, which does not require local ground measurements of weather or rainfall, or estimates of soil texture. The algorithm relies on general conservation of the ratio between actual ET and a reference ET, generated from satellite insolation data and standard meteorological fields from a mesoscale model. The algorithm was tested with ET retrievals from the Atmosphere–Land Exchange Inverse (ALEXI) surface energy balance model and associated DisALEXI flux disaggregation technique, which uses Landsat-scale thermal imagery to reduce regional ALEXI maps to a finer spatial resolution. Daily ET at the Landsat scale was compared with lysimeter and eddy covariance flux measurements collected during the Bushland Evapotranspiration and Agricultural Remote sensing EXperiment of 2008 (BEAREX08), conducted in an irrigated agricultural area in the Texas Panhandle under highly advective conditions. The simple gap-filling algorithm performed reasonably at most sites, reproducing observed cumulative ET to within 5–10% over the growing period from emergence to peak biomass in both rainfed and irrigated fields.
Neurocysticercosis is a neurologic parasitic disease caused by the encysted larva of the tapeworm Taenia solium and is the most important parasitic disease of the human central nervous system. It is ...the most common cause of acquired epilepsy in endemic settings and constitutes a public health challenge for most of the developing world. Nowadays, however, as a result of globalization, neurocysticercosis is being seen more frequently in developed countries as well. Neurocysticercosis is acquired through fecal-oral contamination, and the disease course is complex, with two intermediate hosts (ie, pigs and humans) and a definitive host (humans). Traditionally, it has been classified into active and nonactive forms according to disease location. Radiologists must be aware of its imaging appearance, which is quite variable, as is the differential diagnosis. Imaging findings depend on several factors, including the stage of the life cycle of T solium at presentation; the number and location (ie, subarachnoid, cisternal, or intraventricular) of parasites; and associated complications such as vascular involvement (ie, arteritis with or without infarction), inflammatory response (ie, edema, gliosis, or arachnoiditis), and, in ventricular forms, degree of obstruction. Thus, the diagnostic approach, management, and prognosis for neurocysticercosis differ widely depending on the type of infection.
Biomarkers are relevant indicators of the physiological state of an individual. Although biomarkers can be found in diseased tissue and different biofluids, sampling from blood plasma is relatively ...easy and less invasive. Among the molecular biomarkers that can be found circulating in plasma are proteins, metabolites, nucleic acids, and exosomes. Some of these plasma‐circulating biomarkers are now employed for patient stratification in a broad range of diseases with high sensitivity and specificity and are useful in early diagnosis, initial risk assessment, and therapy selection. However, there is a pressing need to develop novel approaches for biomarker analysis that can be translated into clinical or other settings without complex methodologies or instrumentation. Microfluidics has been touted as a promising technology to carry out this task because it offers high‐throughput, automation, multiplexed detection, and portability, possibly overcoming the bottleneck that prevent the translation of novel biomarkers to the point‐of‐care (POC). Here, we provide a review of the microfluidic systems that have been engineered to detect circulating molecular biomarkers in blood plasma. We also review the different microfluidic approaches for plasma enrichment, which are now being integrated with microfluidic‐based biomarker analyzers. Such integration should lead to cost‐effective solutions in in vitro diagnostics, with special relevance to POC platforms.
In this study, the performance of a one‐source surface energy balance (OSEB) remote sensing (RS) of actual crop evapotranspiration (ETa), incorporating data from different spaceborne, airborne and ...proximal multispectral data, was evaluated. The RS platforms in this study included Landsat‐8 (30 m pixel size), Sentinel‐2 (10 m), Planet CubeSat (3 m), a handheld (proximal) multispectral radiometer (MSR) (1 m) and an unmanned aerial system (UAS) (0.03 m). A 2‐year data set (2020 and 2021) from two maize research sites in Greeley and Fort Collins, Colorado, USA, provided ground‐based data for estimating and evaluating hourly ETa from the OSEB algorithm. The accuracy of OSEB hourly maize ETa estimates was evaluated using calculated hourly maize ETa using high‐frequency data collected with an eddy covariance energy balance system installed at each research site. The results indicated that the Planet CubeSat multispectral sensor (3 m), combined with on‐site surface temperature data, yielded the least errors when predicting maize ETa. The hourly ETa estimation errors for the Planet CubeSat were MBE ± RMSE of −0.02 (−3%) ± 0.07 (13%) mm h⁻1. These results suggest the urgent need for a specific approach to improve RS multispectral and thermal radiometric data (quality) to better support sustainable irrigation water management practices.
Résumé
Dans cette étude, la performance d'un système de bilan énergétique de surface à source unique (OSEB) en télédétection de l'évapotranspiration réelle (ETa) des cultures, intégrant des données multispectrales provenant de différentes plates‐formes spatiales, aériennes et proximales, a été évaluée. Les plates‐formes de télédétection utilisées dans cette étude comprenaient Landsat‐8 (taille de pixel de 30 m), Sentinel‐2 (10 m), Planet CubeSat (3 m), un radiomètre multispectral portatif (ou MSR) de 1 m et un véhicule aérien sans pilote (UAS) de 0,03 m. Un jeu de données de deux ans (2020 et 2021) provenant de deux sites de recherche sur le maïs à Greeley et Fort Collins, Colorado, États‐Unis, a fourni les données au sol pour estimer et évaluer l'ETa horaire à partir de l'algorithme OSEB. La précision des estimations horaires de l'ETa du maïs par OSEB a été évaluée en utilisant l'ETa horaire calculée à partir de données à haute fréquence collectées avec un système de bilan d'énergie à covariance turbulente installé sur chaque site de recherche. Les résultats ont indiqué que le capteur multispectral Planet CubeSat (3 m), combiné aux données de température de surface sur site, produisait le moins d'erreurs lors de la prédiction de l'ETa du maïs. Les erreurs d'estimation horaire de l'ETa, pour le capteur Planet CubeSat, étaient de MBE ± RMSE de ‐0,02 (‐3%) ± 0,07 (13%) mm h⁻1. Ces résultats suggèrent un besoin urgent d'une approche spécifique pour améliorer la qualité des données radiométriques multispectrales et thermiques en télédétection afin de mieux soutenir les pratiques durables de gestion de l'irrigation.
Since the number of drugs based on natural products (NPs) represents a large source of novel pharmacological entities, NPs have acquired significance in drug discovery. Peru is considered a ...megadiverse country with many endemic species of plants, terrestrial, and marine animals, and microorganisms. NPs databases have a major impact on drug discovery development. For this reason, several countries such as Mexico, Brazil, India, and China have initiatives to assemble and maintain NPs databases that are representative of their diversity and ethnopharmacological usage. We describe the assembly, curation, and chemoinformatic evaluation of the content and coverage in chemical space, as well as the physicochemical attributes and chemical diversity of the initial version of the Peruvian Natural Products Database (PeruNPDB), which contains 280 natural products. Access to PeruNPDB is available for free ( https://perunpdb.com.pe/ ). The PeruNPDB's collection is intended to be used in a variety of tasks, such as virtual screening campaigns against various disease targets or biological endpoints. This emphasizes the significance of biodiversity protection both directly and indirectly on human health.
•Surface aerodynamic temperature changes with different maize canopy biomass conditions.•An approach for surface aerodynamic temperature modeling based on ranges of maize leaf area index.•Turbulent ...mixing-row resistance new term proposed to improve sensible heat modeling.•Sensible and latent heat fluxes estimation improvement based on an optimized surface aerodynamic temperature model.
Typical errors for single-source sensible heat flux estimation models range from 15-40% for vegetated surfaces, with 10 to 20% errors introduced by atmosphere stability functions and remaining errors due to the quality of the input data and assumptions regarding the surface aerodynamic temperature (To). This paper describes the development and evaluation of an optimized To model, which serves as key input to estimate and improve sensible heat fluxes for maize fields. The best resulting optimized linear model included four variables: air temperature, surface temperature, fractional vegetation cover, and a proposed new variable that accounts for wind speed and the relative angle of attack between wind direction and crop row orientation. During the 2017 to 2019 maize growing seasons, on two different fields located at a Research Farm near Greeley, Colorado, USA, field data were collected. Micrometeorological data were measured in situ at the height of 3.30 m above the ground surface. Nadir-looking stationary infrared thermometers measured surface temperature. Multispectral surface reflectance data were collected on-site weekly using a handheld multispectral radiometer. Net radiation and soil heat fluxes were acquired at approximately ¼ and ½ of the field's length. Sensible heat fluxes were measured with two sets of Large Aperture Scintillometers to calibrate the To model. A one-way Analysis of Variance was performed to model To for different ranges of maize leaf area index values. A local sensitivity analysis was performed to identify the most influential explanatory variables in the To optimization model. The sensitivity analysis indicated that uncertainty on air temperature and surface temperature measurements were responsible for the most variability in sensible heat flux estimates when using the developed optimized To model. Overall, results indicated that the optimized To model improved the estimation of maize sensible heat fluxes by 31%; which resulted in an improvement on latent heat flux (or evapotranspiration) by 9% compared to a non-optimized linear To model. The interactions between the crop row layout and wind direction promote more turbulent mixing for heat transfer mechanisms.
► Measurement location within the interrow distinctly affected the diurnal timing of E. ► Total daytime or nighttime E was not affected by measurement location. ► Row orientation affected the ...resistance to the turbulent transport of E. ► This effect was not observed under high wind speed conditions.
Agricultural productivity has increased in the Texas High Plains at the cost of declining water tables, putting at risk the sustainability of the Ogallala Aquifer as a principal source of water for irrigated agriculture. This has led area producers to seek alternative practices that can increase water use efficiency (WUE) through more careful management of water. One potential way of improving WUE is by reducing soil evaporation (E), thus reducing overall evapotranspiration (ET). Before searching for ways to reduce E, it is first important to quantify E and understand the factors that determine its magnitude. The objectives of this study were (1) to quantify E throughout part of the growing season for irrigated cotton in a strongly advective semi-arid region; (2) to study the effects of LAI, days after irrigation, and measurement location within the row on the E/ET fraction; and (3) to study the ability of microlysimeter (ML) measures of E combined with sap flow gage measures of transpiration (T) to accurately estimate ET when compared with weighing lysimeter ET data and to assess the E/T ratio. The research was conducted in an irrigated cotton field at the Conservation & Production Research Laboratoryof the USDA-ARS, Bushland, TX. ET was measured by a large weighing lysimeter, and E was measured by 10 microlysimeters that were deployed in two sets of 5 across the interrow. In addition, 10 heat balance sap flow gages were used to determine T. A moderately good agreement was found between the sum E+T and ET (SE=1mm or ∼10% of ET). It was found that E may account for >50% of ET during early stages of the growing season (LAI<0.2), significantly decreasing with increase in LAI to values near 20% at peak LAI of three. Measurement location within the north-south interrows had a distinct effect on the diurnal pattern of E, with a shift in time of peak E from west to east, a pattern that was governed by the solar radiation reaching the soil surface. However, total daily E was unaffected by position in the interrow. Under wet soil conditions, wind speed and direction affected soil evaporation. Row orientation interacted with wind direction in this study such that aerodynamic resistance to E usually increased when wind direction was perpendicular to row direction; but this interaction needs further study because it appeared to be lessened under higher wind speeds.
The Surface Energy Balance Algorithm for Land (SEBAL) is one of the remote sensing (RS) models that are increasingly being used to determine evapotranspiration (ET). SEBAL is a widely used model, ...mainly due to the fact that it requires minimum weather data, and also no prior knowledge of surface characteristics is needed. However, it has been observed that it underestimates ET under advective conditions due to its disregard of advection as another source of energy available for evaporation. A modified SEBAL model was therefore developed in this study. An advection component, which is absent in the original SEBAL, was introduced such that the energy available for evapotranspiration was a sum of net radiation and advected heat energy. The improved SEBAL model was termed SEBAL-Advection or SEBAL-A. An important aspect of the improved model is the estimation of advected energy using minimal weather data. While other RS models would require hourly weather data to be able to account for advection (e.g., METRIC), SEBAL-A only requires daily averages of limited weather data, making it appropriate even in areas where weather data at short time steps may not be available. In this study, firstly, the original SEBAL model was evaluated under advective and non-advective conditions near Rocky Ford in southeastern Colorado, a semi-arid area where afternoon advection is common occurrence. The SEBAL model was found to incur large errors when there was advection (which was indicated by higher wind speed and warm and dry air). SEBAL-A was then developed and validated in the same area under standard surface conditions, which were described as healthy alfalfa with height of 40-60 cm, without water-stress. ET values estimated using the original and modified SEBAL were compared to large weighing lysimeter-measured ET values. When the SEBAL ET was compared to SEBAL-A ET values, the latter showed improved performance, with the ET Mean Bias Error (MBE) reduced from -17.1% for original SEBAL to 2.2% for SEBAL-A and the Root Mean Square Error (RMSE) reduced from 25.1% to 10.9%, respectively. It was therefore concluded that the developed SEBAL-A model was capable of accounting for advection and therefore suitable for arid and semi-arid regions where advection is common.
We report a comprehensive fragment library with 205,903 fragments derived from the recently published Collection of Open Natural Products (COCONUT) data set with more than 400,000 non‐redundant ...natural products. The natural products‐based fragment library was compared with other two fragment libraries herein generated from ChEMBL (biologically relevant compounds) and Enamine‐REAL (a large on‐demand collection of synthetic compounds), both used as reference data sets with relevance in drug discovery. It was found that there is a large diversity of unique fragments derived from natural products and that the entire structures and fragments derived from natural products are more diverse and structurally complex than the two reference compound collections. During this work we introduced a novel visual representation of the chemical space based on the recently published concept of statistical‐based database fingerprint. The compounds and fragments libraries from natural products generated and analyzed in this work are freely available.
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