scholarly journals A novel role for carbonic anhydrase: cytoplasmic pH gradient dissipation in mouse small intestinal enterocytes

1999 ◽  
Vol 516 (1) ◽  
pp. 209-217 ◽  
Author(s):  
A. K. Stewart ◽  
C. A. R. Boyd ◽  
R. D. Vaughan-Jones
Keyword(s):  
Carbonic Anhydrase ◽  
Ph Gradient ◽  
Cytoplasmic Ph ◽  
Small Intestinal ◽  
Intestinal Enterocytes

scholarly journals Carbonic anhydrase generates a pH gradient in Bombyx mori silk glands

2015 ◽  
Vol 65 ◽  
pp. 100-106 ◽  
Author(s):  
L.J. Domigan ◽  
M. Andersson ◽  
K.A. Alberti ◽  
M. Chesler ◽  
Q. Xu ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Bombyx Mori ◽  
Ph Gradient ◽  
Silk Glands ◽  
Bombyx Mori Silk

Small Intestinal Enterocytes

1993 ◽  
pp. 193-201
Author(s):  
Tak Yee Aw ◽  
Changli Bai ◽  
Dean P. Jones
Keyword(s):  
Small Intestinal ◽  
Intestinal Enterocytes

scholarly journals Histochemical localisation of carbonic anhydrase in the digestive tract and salivary glands of the house cricket, Acheta domesticus

2020 ◽  
Vol 6 (2) ◽  
pp. 191-198
Author(s):  
E. Thorsson ◽  
A. Jansson ◽  
M. Vaga ◽  
L. Holm
Keyword(s):  
Carbonic Anhydrase ◽  
Salivary Glands ◽  
Digestive Tract ◽  
Cell Types ◽  
Acheta Domesticus ◽  
Ph Gradient ◽  
House Cricket ◽  
Main Cell ◽  
Cellular Localisation ◽  
Luminal Ph

The house cricket (Acheta domesticus) is one of several cricket species with great potential to be farmed as a sustainable protein source. In order to succeed in large-scale cricket farming, knowledge of cricket digestion is essential. The digestive tract morphology of A. domesticus is well documented, but knowledge of the salivary glands is lacking. In the digestive tract of insects, the carbonic anhydrase (CA) enzyme family is believed to contribute to the luminal pH gradient. Presence of CA in the digestive tract of A. domesticus has been reported, but not the cellular localisation. This study examined the digestive tract of A. domesticus, including salivary glands, and the cellular localisation and activity of CA in fed or starved (48 h) males and females. Tissues were collected from third-generation offspring of wild A. domesticus captured in Sweden and the histology of the salivary glands and the cellular localisation of CA in the digestive tract of A. domesticus were determined, to our knowledge for the first time. The salivary glands resembled those of grasshoppers and locusts, and we suggest the two main cell types present to be parietal and zymogenic cells. Histochemical analysis revealed that CA activity was localised in midgut epithelium, both main cell types of salivary gland, and muscle along the entire digestive tract. These findings support the suggestion that CA contributes to digestive tract luminal pH gradient, by driving acidic secretions from the salivary glands and alkaline secretions from the midgut. Starvation resulted in significantly reduced body size and weight, but neither starvation nor sex had any effect on CA activity or localisation.

scholarly journals TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes

2020 ◽  
Vol 5 (47) ◽  
pp. eabc3582 ◽  
Author(s):  
Ruochen Zang ◽  
Maria Florencia Gomez Castro ◽  
Broc T. McCune ◽  
Qiru Zeng ◽  
Paul W. Rothlauf ◽  
...  
Keyword(s):  
Serine Proteases ◽  
Gastrointestinal Symptoms ◽  
Host Cells ◽  
Productive Infection ◽  
Intestinal Lumen ◽  
Fecal Shedding ◽  
Oral Transmission ◽  
Stool Specimens ◽  
Small Intestinal ◽  
Intestinal Enterocytes

Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA are frequently observed in COVID-19 patients. However, it is unclear whether SARS-CoV-2 replicates in the human intestine and contributes to possible fecal-oral transmission. Here, we report productive infection of SARS-CoV-2 in ACE2+ mature enterocytes in human small intestinal enteroids. Expression of two mucosa-specific serine proteases, TMPRSS2 and TMPRSS4, facilitated SARS-CoV-2 spike fusogenic activity and promoted virus entry into host cells. We also demonstrate that viruses released into the intestinal lumen were inactivated by simulated human colonic fluid, and infectious virus was not recovered from the stool specimens of COVID-19 patients. Our results highlight the intestine as a potential site of SARS-CoV-2 replication, which may contribute to local and systemic illness and overall disease progression.

Proton motive force as a function of the pH at which Methanobacterium bryantii is grown

1985 ◽  
Vol 31 (11) ◽  
pp. 1031-1034 ◽  
Author(s):  
G. Dennis Sprott ◽  
Sharon E. Bird ◽  
Ian J. McDonald
Keyword(s):  
Membrane Potential ◽  
Proton Motive Force ◽  
Motive Force ◽  
Ph Gradient ◽  
Alkaline Media ◽  
Cytoplasmic Ph ◽  
Acidic Media ◽  
Generation Times ◽  
Optimum Ph ◽  
Ph Range

Methanobacterium bryantii was grown on CO2 and H2 over a pH range between the extremes of 5.0 and 8.1. Generation times were shortest between pH 6.6 and 7.1. Cells grown at optimum pH had a proton motive force consisting predominantly of the membrane potential but those grown at nonoptimal pH generated a transmembrane pH gradient as well. This pH gradient was, however, insufficient to maintain a constant cytoplasmic pH during growth in very acidic or basic media. The results suggest that in acidic media growth may be limited by the cytoplasmic pH and that in alkaline media it may be limited by the cytoplasmic pH and (or) by the magnitude of the proton motive force.

Importance of sodium to the bioenergetic properties of Methanococcus voltae

1985 ◽  
Vol 31 (9) ◽  
pp. 851-855 ◽  
Author(s):  
Ken F. Jarrell ◽  
G. D. Sprott
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Maximum Velocity ◽  
Ph Gradient ◽  
Cytoplasmic Ph ◽  
Alkaline Ph ◽  
Methanococcus Voltae

The marine methanogen Methanococcus voltae has distinct sodium requirements for active transport and for methanogenesis. These requirements were separated by demonstrating that each process has very different sodium optima, and that sodium increases the affinity of the isoleucine transport system at least 15-fold without altering the maximum velocity. The cytoplasmic pH became alkaline upon activating methane synthesis by sodium. Ionophores collapsed the transmembrane pH gradient, and inhibited methanogenesis and transport. Comparisons of pH responses indicate that growth is limited at alkaline pH by a factor(s) other than the rates of transport of leucine or isoleucine, or methanogenesis.

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