Valve morphogenesis in the centric diatom Proboscia alata Sundstrom

Abstract

Valve morphogenesis in Proboscia alata Sundstrom was followed in living cells and during treatment with antiactin and antimicrotubule drugs. Once cleaved, sibling cells rounded up and retracted. Soon, a granular organizing center (OC) appeared adjacent to the stub of the initiated valve. Silicification started within a silicon deposition vesicle (SDV) adjacent to the OC. The elongating valve was initially tubular and sealed at one end, creating the proboscis of the conical valve. The edge of the SDV and thinnest region of the forming valve was lined by a sleeve of bundled microtubules (MTs) that terminated short of the older more rigid part of the valve. The growing proboscis of living cells..