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.
Subject(s)
Cell Nucleus/physiology , Gene Expression Regulation, Fungal , Genes, Fungal , Genes, Mating Type, Fungal , Schizophyllum/genetics , Fungal Proteins/genetics , Fungal Proteins/metabolism , Immunohistochemistry , RNA, Fungal/analysis , RNA, Fungal/genetics , RNA, Messenger/analysis , RNA, Messenger/genetics , Schizophyllum/growth & development , Schizophyllum/ultrastructureABSTRACT
The Sc7 and Sc14 genes are specifically expressed in the dikaryon of the basidiomycete fungus Schizophyllum commune during fruiting. These genes are closely linked (within 6 kb) and highly similar in gene structure and nucleotide sequence (70% identical nucleotides in their coding regions). The encoded proteins (204 and 214 amino acids, respectively) have 87% similarity in amino acids (56% of the amino acids are identical). They contain putative signal sequences for secretion, are rich in aromatic amino acids which are generally located at similar positions, and they are generally hydrophilic. Inspection of databanks showed similarities with pathogenesis-related proteins (PR1) from plants, testis-specific proteins from mammals and venom allergen proteins from insects. An antibody raised against a Sc7 fusion protein showed the presence of the Sc7 protein in the culture medium and in the fruit bodies where it is apparently loosely associated with hyphal walls.
Subject(s)
Fungal Proteins/genetics , Genes, Fungal , Schizophyllum/genetics , Amino Acid Sequence , Base Sequence , Extracellular Space/metabolism , Fungal Proteins/metabolism , Molecular Sequence Data , Multigene Family , Schizophyllum/growth & development , Schizophyllum/metabolism , Sequence Homology, Amino AcidABSTRACT
A derivative of the pEX3 expression vector was constructed that codes for the first 407 amino acids of the 1051 amino acids of the pEX3 fusion protein. The amount of truncated fusion protein (40 mg/g cells), obtained by expression in E. coli, was similar to that produced by the original pEX3 vector. The truncated fusion protein was purified more easily from E. coli contaminants than the original fusion protein by washing with 2 M urea and 0.5% Triton X-100.
Subject(s)
Galactosidases/isolation & purification , Genetic Vectors , Plasmids , Recombinant Fusion Proteins/isolation & purification , Recombinant Proteins/isolation & purification , beta-Galactosidase/isolation & purification , Cloning, Molecular , Electrophoresis, Polyacrylamide Gel , Escherichia coli/genetics , Gene Expression Regulation , Recombinant Fusion Proteins/biosynthesis , Recombinant Fusion Proteins/genetics , beta-Galactosidase/biosynthesis , beta-Galactosidase/geneticsABSTRACT
Synthetic analogues of atrial natriuretic factor (ANF) have been developed for potential use as therapeutic agents in the treatment of congestive heart failure and hypertension. We studied the effects of 14 intravenous infusions of synthetic ANF (anaritide, human ANF 102-126) on coronary hemodynamics and myocardial energetics in six patients with heart failure. ANF infusion caused no change in coronary blood flow and a fall in coronary vascular resistance from 1.22 +/- 0.22 to 1.08 +/- 0.18 mm Hg-min/ml (p less than 0.05). Myocardial oxygen and lactate consumption were unchanged from baseline values. Mean arterial pressure fell from 91 +/- 4 to 78 +/- 3 mm Hg (p less than 0.01), right atrial pressure fell from 10 +/- 1 to 8 +/- 1 mm Hg (p less than 0.01), pulmonary capillary wedge pressure fell from 21 +/- 3 to 16 +/- 2 mm Hg (p less than 0.01), heart rate and cardiac index were unchanged, and systemic vascular resistance fell from 1346 +/- 130 to 1087 +/- 98 dyne-sec/cm5 (p less than 0.05). We conclude that infusion of ANF in hemodynamically effective doses in patients with heart failure decreases coronary vascular resistance with no change in coronary blood flow or myocardial oxygen or lactate metabolism.
