title: Ultrastructural features of the early secretory pathway in Trichoderma reesei.
abstract: We have systematically analysed the ultrastructure of the early secretory pathway in the Trichoderma reesei hyphae in the wild-type QM6a, cellulase-overexpressing Rut-C30 strain and a Rut-C30 transformant BV47 overexpressing a recombinant BiP1-VenusYFP fusion protein with an endoplasmic reticulum (ER) retention signal. The hyphae were studied after 24 h of growth using transmission electron microscopy, confocal microscopy and quantitative stereological techniques. All three strains exhibited different spatial organisation of the ER at 24 h in both a cellulase-inducing medium and a minimal medium containing glycerol as a carbon source (non-cellulase-inducing medium). The wild-type displayed a number of ER subdomains including parallel tubular/cisternal ER, ER whorls, ER-isolation membrane complexes with abundant autophagy vacuoles and dense bodies. Rut-C30 and its transformant BV47 overexpressing the BiP1-VenusYFP fusion protein also contained parallel tubular/cisternal ER, but no ER whorls; also, there were very few autophagy vacuoles and an increasing amount of punctate bodies where particularly the recombinant BiP1-VenusYFP fusion protein was localised. The early presence of distinct strain-specific features such as the dominance of ER whorls in the wild type and tub/cis ER in Rut-C30 suggests that these are inherent traits and not solely a result of cellular response mechanisms by the high secreting mutant to protein overload.
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Marko
authors.initials: M
authors.lastname: Nykänen
authors.affiliation: Microscopy Unit, Faculty of Science, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Debra
authors.initials: D
authors.lastname: Birch
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Department of Chemistry and Biomolecular Sciences, Biomolecular Frontiers Research Centre, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Robyn
authors.initials: R
authors.lastname: Peterson
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Westmead Millenium Institute, 176 Hawkesbury Rd, Westmead, NSW, 2145, Australia.
authors.forename: Hong
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Department of Chemistry and Biomolecular Sciences, Biomolecular Frontiers Research Centre, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Liisa
authors.initials: L
authors.lastname: Kautto
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Department of Chemistry and Biomolecular Sciences, Biomolecular Frontiers Research Centre, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Anna
authors.initials: A
authors.lastname: Gryshyna
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.|Department of Chemistry and Biomolecular Sciences, Biomolecular Frontiers Research Centre, Macquarie University, Sydney, NSW, 2109, Australia.
authors.forename: Junior
authors.initials: J
authors.lastname: Te'o
authors.affiliation: Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia. helena.nevalainen@mq.edu.au.|Department of Chemistry and Biomolecular Sciences, Biomolecular Frontiers Research Centre, Macquarie University, Sydney, NSW, 2109, Australia. helena.nevalainen@mq.edu.au.
authors.forename: Helena
authors.initials: H
authors.lastname: Nevalainen
mesh_terms: D001343:Autophagy; D004721:Endoplasmic Reticulum / Q000648:ultrastructure; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D055571:Secretory Pathway; D014242:Trichoderma / Q000648:ultrastructure*
keywords: ER subdomains; Early secretory compartment; Morphometry; Stereology; TEM; Trichoderma reesei