Histidine is an essential amino acid that is also a precursor for metabolites implicated in the immune system, pulmonary ventilation, and vascular circulation. Absorption of dietary histidine relies largely on the sodium-coupled neutral amino acid transport by the Broad neutral amino acid transporter (BAT) present on the apical membrane of the enterocyte. Here, we demonstrate the absorption of histidine by the intestinal villus enterocytes from the lumen using goat jejunal inverted sacs. The jejunal sacs exposed to varying concentrations of sodium and histidine were assayed to determine the concentration of histidine inside the sacs as a function of time. The results show active histidine absorption. Increasing the concentration of salt resulted in higher absorption of histidine, suggesting a symport of sodium and histidine absorption in goat intestinal inverted sacs. This protocol may be applied to visualize the intestinal mobility of amino acids or other metabolites with appropriate modifications. We propose this experiment as an experiential pedagogical tool that can help undergraduate students comprehend the concept of membrane transport.
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http://dx.doi.org/10.3791/66882 | DOI Listing |
J Vis Exp
October 2024
Department of Biochemistry, Sri Venkateswara College, University of Delhi;
Histidine is an essential amino acid that is also a precursor for metabolites implicated in the immune system, pulmonary ventilation, and vascular circulation. Absorption of dietary histidine relies largely on the sodium-coupled neutral amino acid transport by the Broad neutral amino acid transporter (BAT) present on the apical membrane of the enterocyte. Here, we demonstrate the absorption of histidine by the intestinal villus enterocytes from the lumen using goat jejunal inverted sacs.
View Article and Find Full Text PDFJ Am Chem Soc
November 2023
Department of Chemistry and Engineering Research Center of Advanced Rare-Earth Materials of Ministry of Education, Tsinghua University, Beijing 100084, China.
Electronic structure is essential to understanding the catalytic mechanism of metal single-atom catalysts (SACs), especially under electrochemical conditions. This study delves into the nuanced modulation of "frontier orbitals" in SACs on nitrogen-doped graphene (N-C) substrates by electrochemical potentials. We observe shifts in Fermi level and changes of d-orbital occupation with alterations in electrochemical potentials, emphasizing a synergy between the discretized atomic orbitals of metals and the continuous bands of the N-C based environment.
View Article and Find Full Text PDFJACS Au
May 2022
Center of Advanced Nanocatalysis (CAN), Department of Applied Chemistry, University of Science and Technology of China, Hefei 230026, P. R. China.
Supported single-atom catalysts (SACs), with the extremely homogenized active sites could achieve high hydrogenation selectivity toward one of the functional groups coexisting in the reactant molecule. However, as to the target group, the control of selective recognition and activation by SACs still remains a challenge. Herein, the phase engineering of the support is adopted to control the chemo-recognition behavior of SACs in selective hydrogenation.
View Article and Find Full Text PDFFront Plant Sci
November 2021
Unidad de Biotecnología Vegetal, CIATEJ, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, A.C., Zapopan, Mexico.
Asparagaceae's large embryo sacs display a central cell nucleus polarized toward the chalaza, which means the sperm nucleus that fuses with it during double fertilization migrates an atypical long distance before karyogamy. Because of the size and inverted polarity of the central cell in Asparagaceae, we hypothesize that the second fertilization process is supported by an F-actin machinery different from the short-range F-actin structures observed in and other plant models. Here, we analyzed the F-actin dynamics of , a classical Asparagaceae, before, during, and after the central cell fertilization.
View Article and Find Full Text PDFCell Rep
May 2020
Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel. Electronic address:
An antagonistic center-surround receptive field is a key feature in sensory processing, but how it contributes to specific computations such as direction selectivity is often unknown. Retinal On-starburst amacrine cells (SACs), which mediate direction selectivity in direction-selective ganglion cells (DSGCs), exhibit antagonistic receptive field organization: depolarizing to light increments and decrements in their center and surround, respectively. We find that a repetitive stimulation exhausts SAC center and enhances its surround and use it to study how center-surround responses contribute to direction selectivity.
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