Processes Affecting the Growth of Phycomyces Sporangiophores

Citation

Goodell, Ernest William (1970) Processes Affecting the Growth of Phycomyces Sporangiophores. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/DQ76-Z557. https://resolver.caltech.edu/CaltechETD:etd-08082006-104559

Abstract

The stage IV sporangiophore (spph) of Phycomyces is a very large single cell. It is 0.1 mm in diameter and grows to a length of 10 cm. The sporangiophore bears asexual spores at its tip in a spherical sporangium. The sporangiophore elongates via a 2 mm long growing zone just beneath the sporangium. Most of this thesis deals with the interaction of the growing zone with the rest of the sporangiophore and with the sporangium. The top of the sporangiophore appears to have the most active metabolism. The top 6 mm of the sporangiophore consumes 1/2 of the oxygen. The oxygen consumption of the whole spph and of this 6 mm long section does not change as the spph elongates from 25 mm to 50 mm. The oxygen consumption of the sporangium is very much less than that of the sporangiophore. The whole sporangiophore can grow independently from the mycelium. Similiarly, the top 3 or 4 mm can elongate independently from the rest of the sporangiophore. It can grow for about 10 hours without the lower part of the sporangiophore. For the first 4 hours its rate of growth is nearly normal. The elongation of the sporangiophore is much more dependent upon the sporangium. If the sporangium is removed, the growth of the sporangiophore decreases to 1/10 of the normal rate within 2 hours. Six to sixteen hours after sporangium removal, the sporangiophore produces a branch sporangiophore from the former growing zone (figure 1). The spores in the sporangium appear to synthesize some compound (or compounds) which stimulates the sporangiophore's elongation and inhibits its branching.

Thesis Files