No abstract

A mutant of strain 69–1113a of Neurospora crassa, which shows periodic growth upon both complete and minimal media, was named “clock,” and some of the morphological and genetic differences between this mutant and the “patch” and “wild” strains were investigated. In contrast to the uniform growth of “wild,” the “clock” mutant produces a series of bands formed by cymelike aggregations of hyphae which become progressively more dense and finally mark the end (front) of a growth band. A new growth band is formed by a number of hyphae which grow out as in “wild” strains and dichotomize and form new cymes which again become progressively more dense and finally form a new front. It is shown that “clock” continues its rhythmic growth when cultured in continuous darkness. Some “wild” strains were induced to grow periodically on appropriate media. A medium containing equal quantities of sorbose and sucrose caused strain 65–811A (a “wild”) to produce the “patch” type growth. Random isolation, as well as ordered isolation, of ascospores following a cross between “wild” and “clock” show a 1: 1 segregation indicating that “clock” differs from “wild” by a single gene.

No abstract

Ultrastructural studies of microconidium formation This spores is available in Fungal Genetics Reports:

The investigations described herein were carried out with two standard ('wild') strains and several morphological mutants in order to determine the effect of temperature on the growth rate and, more specificalIy, to study the banding and period of the 'clock' mutants in relation to temperature and growth rate. Strains A description of the strains used is provided below (the roman numeral following most of these descriptions designates the strain's linkage group): 4-121A(TS), 4-137a(TL): standard ('wild') strains of Neuro@ora crassa. Standard strains grow rapidly (approximately 8 cm a day for these strains on complete medium at 25 ° C), produce abtmdant aerial and subsurface growth and nsually some conidia. CLllA: 'clock'. a periodic colonial strain described by Suss~sa~" et al. (1964). The growth bands or 'cycles' are approximately 1.0 cm in length at 25°C on complete medium. (V) CL12a: 'modified clock', a double mutant which has, in addition to the clock allele, another mutant allele called 'mad'. 'Mad' is responsible for the shorter band length of CL12a which is approximately 0.5 cm at 25°C on complete medium. (V) W85a: 'mad', a non-colonial (at temperatures above 15 ° C) nctorphological mutant which has the clock modifier-i allele. (V) El1200: 'osmotic', a strain which is inhibited by high osmotic pressure. (II) P564: 'carpet', a colonial mutant which produces no aerial growth. (II) ¥8743: 'peach', a non-colonial strain which produces quantities of peach colottred conidia. (II) L: 'fluffy', a non-colonial strain in which aerial growth is sparse. (II) 70007: 'colonial-4', a colonial which produces aerial sprays of hyphae, ltsually with much conidiation. (IV) P628: 'fluffyoid'. a non-colonial strain which is aconidial. (IV) R2371: 'shallow', a colonial which grows on the surface of the medium and is very aerobic. (V) B132: 'spray', a semi-colonial strain which produces 'sprays' of aerial hyphae. (V) B106: 'skin', a colonial which does not produce aerial growth or conidia. (VII) These descriptions, strain designations and linkage data are taken from the smnmary of the first 'Neurospora Information Conference' (Publication 950,