Cellular events in growth and germination of giant conidia of Neurospora crassa

During growth of conidia in 3.22 M ethylene glycol the increase in the number of the nuclei is proportional to the increase in volume only in the phase of maximum growth rate and is lower in the preceding and in the following periods of growth. DNA synthesis similarly initiates later and decreases faster than protein synthesis. The dilution of ethylene glycol is followed by the germination of giant conidia, which is characterized by the absence of a lag phase, a high degree of synchrony and the formation of more than one germ tube per conidium. The number of germ tubes is dependent on the volume reached by conidia at the end of the treatment and does not increase with time. The resuming of DNA synthesis after germination is preceded by a sharp increase in protein synthesis and the division of almost half of the nuclei and shows a synchronized pattern. Results are discussed in the light of models of growth proposed for eukaryotic cells.