Rhcg1 and Rhbg mediate ammonia excretion by ionocytes and keratinocytes in the skin of zebrafish larvae: H+-ATPase-linked active ammonia excretion by ionocytes

2013 ◽  
Vol 304 (12) ◽  
pp. R1130-R1138 ◽  
Author(s):  
Tin-Han Shih ◽  
Jiun-Lin Horng ◽  
Yi-Ting Lai ◽  
Li-Yih Lin
Keyword(s):  
Ammonia Excretion ◽  
Apical Surface ◽  
Concentration Gradients ◽  
Skin Cells ◽  
Zebrafish Larvae ◽  
Skin Keratinocytes ◽  
Morpholino Oligonucleotides ◽  
Apical Membranes

In zebrafish, Rhcg1 was found in apical membranes of skin ionocytes [H+-ATPase-rich (HR) cells], which are similar to α-type intercalated cells in mammalian collecting ducts. However, the cellular distribution and role of Rhbg in zebrafish larvae have not been well investigated. In addition, HR cells were hypothesized to excrete ammonia against concentration gradients. In this study, we attempted to compare the roles of Rhbg and Rhcg1 in ammonia excretion by larval skin and compare the capability of skin cells to excrete ammonia against concentration gradients. Using in situ hybridization and immunohistochemistry, Rhbg was localized to both apical and basolateral membranes of skin keratinocytes. A scanning ion-selective electrode technique (SIET) was applied to measure the NH4+ flux at the apical surface of keratinocytes and HR cells. Knockdown of Rhbg with morpholino oligonucleotides suppressed ammonia excretion by keratinocytes and induced compensatory ammonia excretion by HR cells. To compare the capability of cells to excrete ammonia against gradients, NH4+ flux of cells was determined in larvae exposed to serial concentrations of external NH4+. Results showed that HR cells excreted NH4+ against higher NH4+ concentration than did keratinocytes. Knockdown of the expression of either Rhcg1 or H+-ATPase in HR cells suppressed the capability of HR cells.

Ammonia excretion by the skin of zebrafish (Danio rerio) larvae

2008 ◽  
Vol 295 (6) ◽  
pp. C1625-C1632 ◽  
Author(s):  
Tin-Han Shih ◽  
Jiun-Lin Horng ◽  
Pung-Pung Hwang ◽  
Li-Yih Lin
Keyword(s):  
Direct Evidence ◽  
Ammonia Excretion ◽  
Bafilomycin A1 ◽  
Selective Electrode ◽  
Zebrafish Larvae ◽  
Trapping Mechanism ◽  
Morpholino Oligonucleotides ◽  
Electrode Technique ◽  
External Ph ◽  
Freshwater Teleosts

The mechanism of ammonia excretion in freshwater teleosts is not well understood. In this study, scanning ion-selective electrode technique was applied to measure H+ and NH4+ fluxes in specific cells on the skin of zebrafish larvae. NH4+ extrusion was relatively high in H+ pump-rich cells, which were identified as the H+-secreting ionocyte in zebrafish. Minor NH4+ extrusion was also detected in keratinocytes and other types of ionocytes in larval skin. NH4+ extrusion from the skin was tightly linked to acid secretion. Increases in the external pH and buffer concentration (5 mM MOPS) diminished H+ and NH4+ gradients at the larval surface. Moreover, coupled decreases in NH4+ and H+ extrusion were found in larvae treated with an H+-pump inhibitor (bafilomycin A1) or H+-pump gene ( atp6v1a) knockdown. Knockdown of Rhcg1 with morpholino-oligonucleotides also decreased NH4+ excretion. This study demonstrates ammonia excretion in epithelial cells of larval skin through an acid-trapping mechanism, and it provides direct evidence for the involvement of the H+ pump and an Rh glycoprotein (Rhcg1) in ammonia excretion.

scholarly journals Knockdown of Laminin gamma-3 (Lamc3) impairs motoneuron guidance in the zebrafish embryo

2017 ◽  
Vol 2 ◽  
pp. 111
Author(s):  
Alexander M. J. Eve ◽  
James C. Smith
Keyword(s):  
Endothelial Cells ◽  
Zebrafish Embryo ◽  
Axonal Guidance ◽  
Loss Of Function ◽  
Cardinal Vein ◽  
Morpholino Oligonucleotides ◽  
Antisense Morpholino Oligonucleotides ◽  
Antisense Morpholino

Background: Previous work in the zebrafish embryo has shown that laminin γ-3 (lamc3) is enriched in endothelial cells marked by expression of fli1a, but the role of Lamc3 has been unknown. Methods: We use antisense morpholino oligonucleotides, and CRISPR/Cas9 mutagenesis of F0 embryos, to create zebrafish embryos in which lamc3 expression is compromised. Transgenic imaging, immunofluorescence, and in situ hybridisation reveal that Lamc3 loss-of-function affects the development of muscle pioneers, endothelial cells, and motoneurons. Results: Lamc3 is enriched in endothelial cells during zebrafish development, but it is also expressed by other tissues. Depletion of Lamc3 by use of antisense morpholino oligonucleotides perturbs formation of the parachordal chain and subsequently the thoracic duct, but Lamc3 is not required for sprouting of the cardinal vein. F0 embryos in which lamc3 expression is perturbed by a CRISPR/Cas9 approach also fail to form a parachordal chain, but we were unable to establish a stable lamc3 null line. Lamc3 is dispensable for muscle pioneer specification and for the expression of netrin-1a in these cells. Lamc3 knockdown causes netrin-1a up-regulation in the neural tube and there is increased Netrin-1 protein throughout the trunk of the embryo. Axonal guidance of rostral primary motoneurons is defective in Lamc3 knockdown embryos. Conclusions: We suggest that knockdown of Lamc3 perturbs migration of rostral primary motoneurons at the level of the horizontal myoseptum, indicating that laminin γ3 plays a role in motoneuron guidance.

Role of albumin in prevention of edema in perfused rabbit lungs

1981 ◽  
Vol 50 (5) ◽  
pp. 1065-1070 ◽  
Author(s):  
R. S. Chang ◽  
K. Wright ◽  
R. M. Effros
Keyword(s):  
Dry Weight ◽  
Water Volume ◽  
Albumin Concentration ◽  
Concentration Gradients ◽  
Moderate Amount ◽  
Edema Formation ◽  
Vascular Volume ◽  
Wet Weight

Edema formation was studied using in situ rabbit lungs perfused with normal 5.0 g/dl) and low (0.1 g/dl) albumin solutions. Measurements were made of the ratio of wet weight to dry weight of the lungs corrected for the residual vascular volume, [(W/D)ev] and the ratio of extravascular 22Na+ to extravascular water volume. Edema formation in the 5 g/dl lungs was insignificant during a 60-min perfusion interval. A moderate amount of edema was found in 0.1 g/dl lungs: (W/D)ev = 5.30 +/- 0.12 (SE) compared with 4.66 +/- 0.11 in the 5 g/dl lungs. Much greater rates of edema formation were found in the 0.1 g/dl lungs when left atrial pressures were increased from 0 to 10 Torr; (W/D)ev reached 7.89 +/- 0.50 in 60 min compared with 5.66 +/- 0.23 in the 5 g/dl lungs. No additional edema formation occurred when albumin concentrations were decreased from 0.1 g/dl to below 0.01 g/dl. Albumin concentration gradients across the capillary wall appear to increase with elevations in capillary pressure.

{10-12} Twinning Mechanism During In Situ Micro-Tensile Loading of Pure Mg: Role of Basal Slip and Twin-Twin Boundary Interaction

2020 ◽  
Author(s):  
Nicolò Maria della Ventura ◽  
Szilvia Kalácska ◽  
Daniele Casari ◽  
Thomas Edward James Edwards ◽  
Johann Michler ◽  
...  
Keyword(s):  
Twin Boundary ◽  
Basal Slip ◽  
Tensile Loading ◽  
Boundary Interaction

The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

1999 ◽  
Vol 39 (7) ◽  
pp. 91-98 ◽  
Author(s):  
Ryan N. Jordan ◽  
Eric P. Nichols ◽  
Alfred B. Cunningham
Keyword(s):  
Mass Transfer ◽  
Cell Membrane ◽  
Substrate Concentration ◽  
Water Interface ◽  
Industrial Systems ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Surfactant Sorption

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.

THE ROLE OF BACTERIAL COMMUNITIES ON IN-SITU ARSENIC AND IRON CYCLING IN RIVERBANKS ALONG THE MEGHNA RIVER, BANGLADESH

2020 ◽  
Author(s):  
Kimberly D. Myers ◽  
◽  
Katrina Lee Jewell ◽  
P.S.K. Knappett ◽  
Mehtaz M. Lipsi ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Iron Cycling

How Artefacts Do Leadership: A Ventriloquial Analysis

2021 ◽  
pp. 089331892199807
Author(s):  
Jonathan Clifton ◽  
Fernando Fachin ◽  
François Cooren
Keyword(s):  
Organizational Communication ◽  
Recent Work ◽  
Distributed Leadership ◽  
Network Theory ◽  
Actor Network Theory ◽  
Fine Grained ◽  
Naturally Occurring ◽  
Human Actors

To date there has been little work that uses fine-grained interactional analyses of the in situ doing of leadership to make visible the role of non-human as well as human actants in this process. Using transcripts of naturally-occurring interaction as data, this study seeks to show how leadership is co-achieved by artefacts as an in-situ accomplishment. To do this we situate this study within recent work on distributed leadership and argue that it is not only distributed across human actors, but also across networks that include both human and non-human actors. Taking a discursive approach to leadership, we draw on Actor Network Theory and adopt a ventriloquial approach to sociomateriality as inspired by the Montreal School of organizational communication. Findings indicate that artefacts “do” leadership when a hybrid presence is made relevant to the interaction and when this presence provides authoritative grounds for influencing others to achieve the group’s goals.

scholarly journals Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

2021 ◽  
Vol 22 (7) ◽  
pp. 3787
Author(s):  
Hussam Ibrahim ◽  
Philipp Reus ◽  
Anna Katharina Mundorf ◽  
Anna-Lena Grothoff ◽  
Valerie Rudenko ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Transcriptional Repression ◽  
Small Gtpase ◽  
Main Role ◽  
Interacting Proteins ◽  
Casein Kinase 1 ◽  
Bona Fide ◽  
Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

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