The morphological mutant 22B of Aspergillus aureolatus is shown to be a homocaryon carrying a heritable defect which comes to expression under definite conditions. This mutant is characterized by the lack of differentiation at the sterigmata level and elsewhere, resulting in the absence of true conidia under normal conditions. Some physiological aspects of this case of conidium expression are discussed. As well as in the wild type sexual reproduction is lacking.
In the mutant 22B the morphogenetic process of conidiation can be regarded as the qualitative behaviour of a dynamical system depending on the parameters temperature and carbohydrate concentration. At temperatures higher than the critical ones the regulatory system for conidiation is inactivated and the mutant shows full stability. However, temperature and carbohydrate gradient had a mutual interaction: a culture grown on a higher carbohydrate level was capable of compensating, to a certain degree, the effect of high temperatures, which tended to inactivate the regulatory system for conidiation. At lower temperatures the system for conidium differentiation can function normally. Although the growth of the colonies is very limited, the chain of events contributing to conidium formation is not interrupted. But all the conidia formed in such conditions carry a defective hereditary material, which becomes manifest again when conidium differentiation is blocked by higher temperature and/or a lower carbohydrate supply.
The results suggest that the organism under study can be interpreted as a mutant carrying a temperature-sensitive and osmotic-remedial allele.
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Muntanjola-Cvetković, M., Nešković, M. Physiological properties of the cladosarum-like mutant 22B of Aspergillus aureolatus . Archiv. Mikrobiol. 84, 141–152 (1972). https://doi.org/10.1007/BF00412434
- Regulatory System
- Sexual Reproduction
- Mutual Interaction