Are microtubules cold-stable in the Atlantic cod, Gadus morhua?

The amount of axonally transported proteins in the nervus splanchnicus of cod (Gadus morhua) was found to be temperature-dependent in vitro, with an optimum at 8°C. The transport was markedly reduced at 2°C, probably caused by decreased protein synthesis rather than disassembly of microtubules. Microtubules were isolated from cod brain by cycles of assembly-disassembly. These microtubules were cold-labile, had a low amount of microtubule-associated proteins and a high critical concentration for assembly. The possibilities exist that a cold-stabilizing factor or cold-stable microtubules are lost during the preparation, or that cold-stable microtubules are components of the peripheral axons only.