Secondary module density

Where branch primordia are found evenly distributed along the module, but development of primordia into secondary modules is localized or complanate, it can be supposed that the branching pattern seen reflects mechanisms involving control or release of dormancy. The role of auxins, specifically indolyle-3-acelic acid (lAA), in apical donfinance has been shown to be similar to that in vascular plants (see Cooke et al., 2002, for summary), and can be expected to have an important role in the suppression or release from dormancy of branch primordia. For example, if the apical cell of the primary module is producing auxins that suppress development, branch primordia will develop only when they are sufficiently far from the apical cell for the levels of auxin to have dropped to a certain level. Similarly, the density of secondary modules may also reflect auxin control of module development, with branch primordia remaining dormant where the density of secondary modules has reached a local optimum. There is also evidence that lAA can control development of body-plan (i.e., selective development of branch primordia) (Cooke et al., 2002). 

The p subunits could indirectly modulate channel gating and ion conductance by stabilizing relevant a subunit conformations. They also possess immunoglobulin-like folds in their secondary structure analogous to cell-adhesion molecules. So they may interact with extracellular proteins through these folds and then influence the location and density of sodium channels in neural tissues (Bonhaus et al., 1996 Catterall, 2000). 

Figure XX-10 shows a vertical cut through the reference ENHS module (the module) while Fig. XX-11 shows an alternative ENHS module design that uses a lift-pump integrated within the riser. Cover gas from the top of the module is injected into the coolant just above the core. The cover gas bubbles reduce the effective density of coolant in the riser, thus increasing the head for coolant circulation. The circulator would be located above the reactor pool, outside of the module vessel. A lift-pump for the secondary coolant is integrated within the module...

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