The Dna Content of Centrioles Ofneurospora Crassaduring Divisions I and Iv of Ascosporogenesis

Introduction As early as 1897 Harper described bodies in Ascomycete, Erysiphe. Later (1905) he confirmed these observations in mold, Phyllactinia. In both publications term central was chosen by Harper in preference to term centrosphere or centrosome. In 1927 Dodge described in Nez~rosporn tetynspennn a sharply pointed, deeply stained mass at each end of spindle in metaphase I. Dodge called these deeply-stained masses centrosomes. However, in a later publication Dodge, Singleton and Rolniclc (1950) only mentioned probable occurrence of centrioles in N . tetmspenvn. In addition, Singleton ( 195 3) published a description of chromosome cycle in ascus of N . crnssn which included photographs of centrioles. Some of worlc reported in this publication includes earlier material by R~IcClintock (1945) on chromosome and centriole morphology. Somers et nl. (1960) observed in vegetative cycle of N . crnssn an eighth stainable body which they interpreted as a heterochromatic chron~osome. O n other hand, Ward and Ciuryselc (1962) recognized such stainable bodies as centrosomes in their mitotic plates. Weijer et nl. (1965) favor a sinular euplanation. Lu (1964) also reported centrioles in N . cnrssn. Although occurrence of centrosomes and centrioles have been reported in other Ascomycetes (a complete review can be found in Olive, 1953), proof for occurrence of these extra-nuclear bodies in fungi was ohtailled by electron microscopv of ceiltriole of Oomycete, AlO~lg-o cmldirtll ( ~ e r l i n and Bowan, 1964). Lindegren et nl. ( 1965) recentlv published an electron-microphotograph of centriolc of ~ s c o m ~ c e t E , Sncchnronzyces. According to Cleveland (193Sa, 1938b, 1949, 1953), centriole can be regarded as an extra-nuclear bodv n~i th capacity for self-replication. As Wcijer et nl. (1965) pointed ot, capacity for self-replication might appear to qualify centriole as a carrier of genetic factors and hence question of presence and amount of nuclcic acid is crucial (p. 156). This prediction is in line with views of Allazia ( 1961 ), who expected the truly replicating 'germ' in ( t h e ) centriolc to contain only a few replicating l ~ o l c c i ~ l e ~ , while rest of centriolc need contain none (p. 138). It also agrees with recent discovery of D N A in other extra-nuclear bodies such as mitochondria (Schatz et nl., 1964) and cl~loroplasts (Chun et nl., 1963; Cooper and Loring, 1957). The first report on possible occurrence of DhTA in fungal centrioles appeared in litcraturc when U'eijer (1964), using Feulgcn stain on Neurosporn conidia and conidial germination tubes, described Fculgcn-positive centrioles during lcaryokinesis (Juvenile cycle). Recently, Weljer et nl. (1965) published mic~ophotographs of Feulgen-positive centrioles occurring during Maturation cvcles I and I1 of N . crnssn.