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Age-related changes in ultrastructure and chemical composition associated with changes in heat resistance ofNeosartorya fischeriascospores

Authors
Journal
Transactions of the British Mycological Society
0007-1536
Publisher
Elsevier
Publication Date
Volume
89
Issue
4
Identifiers
DOI: 10.1016/s0007-1536(87)80088-8
Disciplines
  • Biology
  • Chemistry

Abstract

Ascospores (10 5/ml) of Neosartorya fischeri var. glaber (FRR 1833) harvested from grape juice agar after 11 d of incubation at 30°C were inactivated by treatment at 82° for 60 min; 25-day-old ascospores survived this heat treatment. To determine if differences in ultrastructure and chemical composition might be related to differences in heat-resistance, ultrastructure as well as protein, lipid, sugar and polyol contents of 11-day-old (heatsensitive) and 25-day-old (heat resistant) ascospores were compared. SEM revealed little difference in external appearance, whereas TEM revealed some internal differences between 11- and 25-day-old ascospores, particularly in the region of germ-tube initiation. Significant qualitative differences in protein content between heat-sensitive and heat-resistant ascospores were observed. The lipid and fatty acid compositions of the two types of ascospore were similar. Heat-resistant ascospores contained higher levels of glycerol, mannitol and trehalose than heat-sensitive ascospores, suggesting that the lowering of internal water activity or membrane stabilization may partially account for increased heat resistance.

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