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The alpha helical CytolysinA family of pore forming toxins (α-PFT) contains single, two, and three component members. Structures of the single component Eschericia coli ClyA and the two component Yersinia enterolytica YaxAB show both undergo conformational changes from soluble to pore forms, and oligomerization to produce the active pore. Here we identify tripartite α-PFTs in pathogenic Gram negative bacteria, including Aeromonas hydrophila (AhlABC).

Initial and concurrent planning in solutions to well-structured problems.

Two experiments are reported, which consider planning behaviour in the context of a well-structured problem. One question in the problem-solving literature is to what extent planning a solution to a problem takes place before attempting that problem and whether this takes precedence over planning while solving a problem, hereafter referred to as concurrent planning. An additional question is whether the adoption of one mode of planning confers a performance advantage and under what circumstances one strategy is adopted in preference to others.