Macromolecular Composition and Nuclear Division During Spore Germination in Aspergillus nidulans

Abstract

S U M M A R YGerm-tube emergence in Aspergillus nidulans exhibits partial synchrony. Germ tubes were first detected at 210 min. after inoculation of spores into a liquid medium. Almost all spores produced germ tubes within 360 min., 4 9 3 % of them doing so between 240 and 300 min. Increase in dry weight was first detected at 120 min. and various constituents at the following times: RNA (30 min.), Kjeldahl nitrogen (30 min.), protein (150 min.) and DNA (180 min.). Pauses in the increase of DNA, RNA and protein were observed. The DNA content per nucleus during the first replication cycle reached twice that of the resting spore, but at later stages of germination values only 10 % higher were observed. Spores containing 2, 4 and 8 nuclei were first detected at 270, 390 and 480 rnin. respectively. Caten, 1969). The present work was undertaken to study nuclear division and macromolecular synthesis during spore germination. I N T R O D U C T I O N METHODSOrganisms. Strain BWB 50 bi I ; w 3 was used throughout this work. The strain, which has white spores and requires biotin, was originally obtained from Glasgow University.Preparation of spore suspensions. Thirty ml. volumes of complete medium agar (MacKintosh & Pritchard, 1963) in 250 ml. conical flasks were inoculated with a spore suspension and incubated at 37" for 7 days. The spores were harvested by adding 20 ml. of 0-1 % (v/v) Tween 80 together with sterile glass beads or marbles. The flasks were agitated and the spore suspensions removed under aseptic conditions and pooled. Spore chains were broken with a Rotamixer (Hook & Tucker Ltd) and hyphal fragments removed by filtration through six layers of sterile muslin. The spores were washed twice and suspended in sterile distilled water. Spore counts were made with a Fuchs-Rosenthal haemocytometer slide, at least 300 spores being counted. Spores thus prepared had a viability of 95 to 99 % after storage at 4" for several days, although the experiments reported here were carried out within 24 h.Cultural conditions and media. Spores were added to 400 ml. of liquid DAN medium containing 50 pg./l. biotin (Trinci, 1969) in a 2 1. conical flask to give a concentration of 21-2

Dormancy, activation and viability of Rhizopus oligosporus sporangiospores

“…However, in view of the large variety of proteins assembled at very early stages of fungal spore germination, further research will be required to ascertain the function of these proteins. The moment in time (2 h) that we detected the first newly synthesized proteins is of comparable order as has been reported for A. nidulans (50 min) (Bainbridge, 1971), Rhizopus stolonifer and Phycomyces blakesleanus spores (2h) (Van Assche and Carlier, 1973). It was also reported Plesofsky-Vig et al, 1992) that cellular proteins were not synthesized by germination ascospores of Neurospora tetrasperma until 90 min after spore activation.…”

The Importance of Fungi to Man

“…This establishment of eight linkage groups has been confirmed using pulsedfield gel electrophoresis, which resolves the eight linkage groups into six bands, two of which are doublets and can be separated using translocation strains. These studies estimated the genome to be 31 megabases (Brody and Carbon 1989), in good agreement with estimates of the size of the genome using reassociation kinetics and colorimetric determination (Bainbridge 1971;Timberlake 1978). Thus, the genome of A. nidulans is 2.5 ‫ן‬ 10 7 to 3.0 ‫ן‬ 10 7 base pairs in size and contains few repetitive DNA sequences.…”

Germination and Outgrowth of Schizosaccharomyces pombe Spores Isolated by a Simple Batch Centrifugation Technique

“…As for the synthetic patterns of macromolecular synthesis, it is apparent that changes in the rates of RNA and protein accumulation are closely linked to cytological events, especially those marking the onset of outgrowth. The order of synthesis of these two components is the same as with many other fungal systems (Allen, 1965 ;Van Etten, 1969 ;Bainbridge, 1971) where RNA synthesis increased before protein synthesis. The pattern in S. pombe differs from the pattern displayed in the budding yeast S. cerevisiae during regrowth.…”