In silico assessment of gene function involved in cysteine biosynthesis in Arabidopsis: expression analysis of multiple isoforms of serine acetyltransferase.

In plants, the inorganic sulfur is first fixed into cysteine by the cysteine biosynthetic pathway. This biosynthetic pathway of cysteine involves several enzymatic reactions. In Arabidopsis thaliana, multiple isoforms seem to participate in each enzymatic step for cysteine biosynthesis. To obtain more insights on the specific role of each isoform involved in the cysteine biosynthesis, in silico analysis of these isoforms using Arabidopsis expressed sequence tags (EST) database was carried out. This EST database analysis revealed distinct population distribution of ESTs among multiple isoforms, suggesting that each isoform has its particular expression pattern, presumably associated with its specific role in cysteine biosynthesis. As another in silico analysis, co-expression analysis of genes involved in sulfur metabolism in Arabidopsis was performed using a public transcriptome database of DNA microarrays. This co-expression analysis also suggested specific function and co-regulation of some isoform genes for cysteine biosynthesis by consideration on the clustering of co-expressed genes. From the results of sensitivity to feedback regulation, subcellular localization and expression of mRNA analyses, each serine acetyltransferase (SATase) isoform seems to have its specific role for cysteine biosynthesis. Similar expression patterns were observed between the experimental results of expression data for SATase isoforms and the in silico results of "digital northern" analysis using EST database.

[Usefulness of transcranial magnetic stimulation in the objective assessment of therapy for adrenoleukodystrophy].

Adrenoleukodystrophy (ALD) is a hitherto untreatable, X-linked recessive disorder of the central nervous system characterized by the systemic accumulation of very-long-chain fatty acids. Although various treatments have been proposed, objective evidence of their efficacy is insufficient. This is partly due to the absence of an appropriate method for evaluating the functions of the central nervous system (CNS). In this study, we took up the central motor conduction time (CMCT) as an index of the CNS functions, and measured it in two patients with ALD under steroid pulse therapy to know if this parameter is useful in assessing the effects of therapy. The right and the left motor cortex was stimulated separately with a MAGSTIM 200 magnetic stimulator, using a round coil of 9cm mean diameter to stimulate the hand area or a double cone coil to stimulate the leg area. CMCT, the time an impulse takes to travel from the motor cortex to the anterior horn cells in the corresponding region, was measured by a combination of transcranial magnetic stimulation (TMS) and F wave technique. Before treatment, CMCT to the cervical cord was prolonged slightly in both patients; CMCT to the lumbar cord was prolonged slightly in one and moderately in the other. After repeated steroid pulse therapy, a definite improvement, although partial and transient, was observed in either case. TMS thus seems to be useful not only for detecting functional derangement of the pyramidal tract but for evaluating the efficacy of therapy for this disease.