to design subsurface drainage systems, it is necessary to determine the saturated hydraulic conductivity of the soil. one of the most common methods for field measurement of this parameter is the shallow well pump-in test method. another method which has recently been introduced for the above measurement is the guelph permeameter method. both methods are used to measure the soil saturated hydra...

CalDAG-GEFI, a guanine nucleotide exchange factor activating Rap1, is known to play a key role in Ca2+-dependent glycoprotein (GP)IIb/IIIa activation and platelet aggregation. Although inhibition of CalDAG-GEFI could be a potential strategy for antiplatelet therapy, no inhibitor of this protein has been identified. In the present study, phenylarsine oxide (PAO), a vicinal dithiol blocker, poten...

Using quantitative phosphopeptide sequencing of unstimulated versus stimulated primary murine Foxp3+ regulatory and Foxp3- conventional T cells (Tregs and Tconv, respectively), we detected a novel and differentially regulated tyrosine phosphorylation site within the C1 domain of the guanine-nucleotide exchange factor CalDAG GEFI. We hypothesized that the Treg-specific and activation-dependent r...

In blood platelets the small GTPase Rap1b is activated by cytosolic Ca2+ and promotes integrin αIIbβ3 inside-out activation and platelet aggregation. cAMP is the major inhibitor of platelet function and antagonizes Rap1b stimulation through a mechanism that remains unclear. In the present study we demonstrate that the Ca2+-dependent exchange factor for Rap1b, CalDAG-GEFI (calcium and diacylglyc...

Calcium-Diacylglycerol Guanine Nucleotide Exchange Factor I (CalDAG-GEFI) has been implicated in platelet aggregation signaling in CalDAG-GEFI knockouts. Functional mutations were identified in the gene encoding for CalDAG-GEFI in 3 dog breeds. Affected dogs experienced epistaxis, gingival bleeding, and petechiation. Platelet number, von Willebrand factor, clot retraction, and coagulation scree...

Single gene mutations in beta integrins can account for functional defects of individual cells of the hematopoietic system. In humans, mutations in beta(2) integrin lead to leukocyte adhesion deficiency (LAD) syndrome and mutations in beta(3) integrin cause the bleeding disorder Glanzmann thrombasthenia. However, multiple defects in blood cells involving various beta integrins (beta(1), beta(2)...

Chemotaxis and integrin activation are essential processes for neutrophil transmigration in response to injury. CalDAG-GEFI plays a key role in the activation of beta1, beta2, and beta3 integrins in platelets and neutrophils by exchanging a GDP for a GTP on Rap1. Here, we explored the role of CalDAG-GEFI and Rap1b in integrin-independent neutrophil chemotaxis. In a transwell assay, CalDAG-GEFI-...