A study was made of the morphology and growth of young mycelia of a temperature-sensitive mutant (sepA2) of Aspergillus nidulans. At 25 °C the mutant grew at the same rate as the parental strain, formed septa and branched normally. At 30 and 37 °C the mutant grew at about three-quarters of the rate of the parental strain and, unlike the parental strain, branched dichotomously. The mutant was aseptate at 37 °C, and at 30 °C produced fewer septa than the parental strain. No septal initials were detected in mutant mycelia grown at 37 °C. Aseptate mycelia of the mutant were grown at 37 °C and then transferred to 25 °C. After transfer to 25 °C, septa appeared parasynchronously throughout aseptate regions of the mycelium previously formed at 37 °C. The intercalary compartments formed in this manner had a mean length which was identical with those of intercalary compartments formed by the parental strain at 37 °C or the mutant at 25 °C. The lag between transfer of mutant mycelia from 37 to 25 °C and the first appearance of septa varied from 0·15 to 2·75 h; the maximum lag observed was similar to the organisms’s doubling time (2·37 h) at 25 °C.
FiddyC., TrinciA. P.J.1976; Mitosis, septation, branching and the duplication cycle in Aspergillus nidulans. Journal of General Microbiology 97:169–184
ReeveJ. N., ClarkD. J.1972; Cell division of Escherichia coli BUG-6: effect of varying the length of growth at the nonpermissive temperature. Journal of Bacteriology 110:117–121
TrinciA. P.J.1978; The duplication cycle and vegetative development in moulds. In The Filamentous FungiIII pp. 132–163SmithJ. E., BerryD. R. Edited by London: Edward Arnold;
TrinciA. P.J.1979; The duplication cycle and branching. In Fungal Walls and Hyphal Growth (in the Press) Edited by BurnettJ. H., TrinciA. P. J. Cambridge: Cambridge University Press;
TrinciA. P.J., CollingeA. J.1973; Structure and plugging of septa of wild type and spreading colonial mutants of Neurospora crassa. Archiv für Mikrobiologie 91:355–364
TrinciA. P.J., RighelatoR. C.1970; Changes in constituents and ultrastructure of hyphal compartments during autolysis of glucose-starved Penicillium chrysogenum. Journal of General Microbiology 60:239–249