title: Positioning of nuclei in the secondary Mycelium of Schizophyllum commune in relation to differential gene expression.
abstract: In this paper we propose a novel type of gene regulation in the MATA|l4 MATB|l4 heterokaryon of Schizophyllum commune by means of differential positioning of the nuclei. It was found that binucleate hyphae with juxtaposed nuclei secrete SC4 hydrophobin (abundant during fruit-body formation), while SC3 (abundant during aerial hyphae formation in both mono- and dikaryons) appeared to be absent. Certain growth conditions disrupted the binucleate state in that the compatible nuclei became separated at a considerable distance. Under these conditions SC4 was not secreted while SC3 was secreted to a high degree. Disruption of the binucleate state was earlier observed in developing aerial hyphae which secrete SC3. Apparently, when the nuclei are in close proximity the dikaryon-expressed genes are switched on by interaction of the products of the MATA and MATB mating-type genes, while SC3 is suppressed by interacting products of the MATB genes, as occurs in the common MATA heterokaryon (MATA= MATB|l4). Growth conditions that lead to disruption of the binucleate state apparently result in abolishment of interaction between the MATB mating-type genes. Under these conditions, dikaryon-specific mRNAs do not accumulate in the MATA|l4 MATB|l4 heterokaryon, while SC3 mRNA becomes highly abundant.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Kerklaan 30, Haren, 9751 NN, The Netherlands.
authors.forename: T A
authors.initials: TA
authors.lastname: Schuurs
authors.forename: H J
authors.initials: HJ
authors.lastname: Dalstra
authors.forename: J M
authors.initials: JM
authors.lastname: Scheer
authors.forename: J G
authors.initials: JG
authors.lastname: Wessels
mesh_terms: D002467:Cell Nucleus / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D007150:Immunohistochemistry; D012331:RNA, Fungal / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012567:Schizophyllum / Q000235:genetics* / Q000254:growth & development / Q000648:ultrastructure
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger