Richard hypothesis 

d/w = resource separation ratio.

d/w < 1, species cannot coexist;

1 < d/w < 3, there will be some competition between species

d/w > 3, species coexist harmoniously

TLS Online TPP Program

#Id: 9085

#XL - T Zoology

Subunit B recognizes and binds to specific gangliosides on the surface of intestinal epithelial cells and provides a route for subunit A to enter. 

TLS Online TPP Program

#Id: 9086

#XL - T Zoology

A1 associates with ARF6, a small G protein in host cells which are accessible only when ARF6 is in its active (GTP-bound) form. 

TLS Online TPP Program

#Id: 9087

#XL - T Zoology

Association with ARF6 activates A1, which catalyzes the transfer of ADP-ribose from NAD to the critical Arg residue in the P loop of the  subunit of Gαs. 

TLS Online TPP Program

#Id: 9088

#XL - T Zoology

TLS Online TPP Program

#Id: 9089

#XL - T Zoology

ADP-ribosylation blocks the GTPase activity of Gαs and renders Gαs permanently active. 

TLS Online TPP Program

#Id: 9090

#XL - T Zoology

This results in continuous activation of the AC of intestinal epithelial cells, chronically active PKA which phosphorylates the CFTR Cl- channel and a Na-H exchanger in the intestinal epithelial cells.