Androgens stimulate fibroblast DNA synthesis at very low (picomolar) concentration, and cell motility at higher (nanomolar) concentration.
We assume that these mutations occurred during recent laboratory passage, in a manner similar to frame-shift inactivation of fliP in H. pylori strain 26695 [ 85], revertants of which can be easily obtained on motility agar at high plating density.
Nonetheless, the results of this study suggest that the rapid onset of sperm motility with activation at high pH following incubation at low pH is probably not based on rapid adjustment of pHi via membrane exchangers/transporters but rather due to an effect of pH on motility-associated processes at the extracellular surface of the sperm.
A mechanism proposed for brine shrimp mortality at high concentrations of hydrophobic carbon nanoparticles is physical adhesion to the exoskeleton and locomotory appendages that decrease motility.
A more recent study in rats found that tetrathiomolybdenum caused a reduction in epididymal weights, sperm concentration, motility, and normal morphology at high dose levels (Lyubimov et al. 2004).
The mean velocities of both components of the continuous protrusion motility module decreased at higher CD concentrations, although the most dramatic decrease was in the fraction of the edge exhibiting these high velocities.
Several hormones of importance for gastrointestinal motility are found at higher plasma concentrations during pregnancy.
In rabbits, López and Alvariño [ 42] found that the sperm motility was increased at higher concentration (10 mM), whilst the lower concentrations (2.5 or 5 mM) did not affect sperm movement.
The function of this additional cluster is unknown, but preliminary results have provided evidence that the SS9 strain displays high motility at 28 MPa pressure and swims very slowly at atmospheric pressure, while the opposite phenotype has been observed in the shallow water 3TCK [ 33].
Results suggest that the flexoelectric motor may generate the power-stroke of hair bundle motility (Fig. 2), at least at high frequencies above ∼200 Hz where ATPase would be too slow to operate on a cycle-by-cycle basis.
