Expression of the eglA gene, encoding for a major endoglucanse EG A in Aspergillus nidulans, is induced by cellulose and cellobiose, but not by xylose. This suggests that induction is independent of XlnR, a transcriptional activator of xylanolytic and cellulolytic genes in Aspergillus. Mutational analysis of the eglA promoter was performed to identify the novel cis-element responsible for XlnR-independent induction. The region spanning -153 to -138 (CCGTACCTTTTTAGGA), designated CeRE(Cellulose Responsive Element), was found to be the upstream activating element essential to inductive expression of the eglA gene.

No abstract

No abstract

In recent years, a number of preconditioners have been applied to linear systems [A.D. Gunawardena, S.K. Jain, L. Snyder, Modified iterative methods for consistent linear systems, Linear Algebra Appl. 154-156 (1991) 123-143; T. Kohno, H. Kotakemori, H. Niki, M. Usui, Improving modified Gauss-Seidel method for Z-matrices, Linear Algebra Appl. 267 (1997) 113-123; H. Kotakemori, K. Harada, M. Morimoto, H. Niki, A comparison theorem for the iterative method with the preconditioner (I + S max ), J. Comput. Appl. Math. 145 (2002) 373-378; H. Kotakemori, H. Niki, N. Okamoto, Accelerated iteration method for Z-matrices, J. Comput. Appl. Math. 75 (1996) 87-97; M. Usui, H. Niki, T.Kohno, Adaptive Gauss-Seidel method for linear systems, Internat. J. Comput. Math. 51(1994)119-125 [10]]. Since these preconditioners are constructed from the elements of the upper triangular part of the coefficient matrix, the preconditioning effect is not observed on the nth row of matrix A. In the present paper, in order to deal with this drawback, we propose a new preconditioner. In addition, the convergence and comparison theorems of the proposed method are established. Simple numerical examples are also given, and we show that the convergence rate of the proposed method is better than that of the optimum SOR.

We propose a preconditioned iterative method with the preconditioning matrix P sm = I + S + S. for Ax = b, where A is an irreducibly diagonal dominant Z-matrix with unit diagonal. The convergence property and the comparison theorem of the proposed method are discussed. Moreover, some numerical examples are reported to confirm the theoretical analysis.