Bis(iodozincio)methane was prepared from diiodomethane and zinc in the presence of a catalytic amount of lead. The compound showed a high potential as an organic synthetic reagent. The reaction with carbonyl compounds proceeded to give methylenated products. The reagent also reacted with a couple of electrophiles sequentially. The function as Lewis acid is also unique. It coordinated with 1, 2-dicarbonyl compounds in face-to-face manner and assisted the stepwise nucleophilic attack on the carbon center of the reagent; the products are cis-1, 2-cyclopropanediols. A structural study was also examined.
(Communicated by Hitosi NOZAKI, M. J. A., March 12, 2003)
The most frequent and malignant brain tumor is the glioblastoma, which may develop de novo (primary glioblastoma) or through progression from low-grade or anaplastic astrocytoma (secondary glioblastoma). These glioblastoma subtypes constitute distinct disease entities that affect patients at different age, and evolve through different genetic pathways. Primary glioblastomas develop in older patients (mean age, 55 years) and typically show EGFR amplification/overexpression, LOH on the entire chromosome 10, PTEN mutations and, occasionally, MDM2 amplification. Secondary glioblastomas develop in younger patients (mean age, 40 years) and typically contain TP53 mutations and/or p14ARF promoter methylation as earliest detectable alterations. Additional changes in the pathway leading to secondary glioblastomas include LOH on 19q and 10q, and RB1 promoter methylation. Common to both primary and secondary glioblastoma is LOH on 10q, distal to the PTEN locus; a putative suppressor gene at 10q25-qter may be largely responsible for the glioblastoma phenotype. The etiology of human gliomas is largely unknown. Hereditary diseases predisposing to the development of gliomas e.g. Li-Fraumeni syndrome, Turcot syndrome, NF1, and NF2 syndromes are rare and cannot explain the development of most of human gliomas. The presence of SV40 large T sequence has been observed in a variety of human brain tumors including gliomas, and they are likely be originated from the contamination of SV40 in poliovaccine between 1955-1962. However, there is no direct evidence that SV40 infection is associated with pathogenesis of human brain tumors. There is recent evidence that G:C→A:T transition mutations at CpG sites in the TP53 gene are significantly more frequent in astrocytic tumors with promoter methylation of the O6-methylguanine-DNA methyltransferase (MGMT) than in those without methylation. This may suggest that endogenous alkylating agents that produce O6-methylguanine or related adducts recognized by MGMT may be involved in the development of astrocytic brain tumors.
(Communicated by Takashi SUGIMURA, M. J. A., March 12, 2003)
NDP kinases (NDPKs) are multifunctional proteins involved in cell proliferation, development, and differentiation in eukaryotes. Previously, we reported that Arabidopsis NDP kinase 2 (AtNDPK2) is a component of H2O2-activated MAPK signaling in plants and demonstrated that its over-expression in plants alters cellular redox conditions (Proc. Natl. Acad. Sci. U. S. A., 100, 358-363, 2003). To elucidate how AtNDPK2 can regulate cellular redox state, we analyzed gene expression profiles of transgenic plants over-expressing AtNDPK2 using cDNA microarray technology. Constitutive over-expression of AtNDPK2 in plants induced numerous genes including those involved in cellular signal transduction and protection, suggesting that NDPKs are also multifunctional in plants. Among the induced genes, we further analyzed the expression of antioxidant genes by Northern blot analysis. Expression of peroxidase, catalase, thioredoxin, thioredoxin reductase, and peroxiredoxin was significantly increased in transgenic plants over-expressing AtNDPK2. Furthermore, the gene expression pattern obtained by Northern blotting was quantitatively consistent with the cDNA microarray analysis. Based on these observations, we suggest that down-regulation of cellular redox state in AtNDPK2 transgenic plants is mediated by genes involved in antioxidant and protective processes.
(Communicated by Yasuyuki YAMADA, M. J. A., March 12, 2003)
Using genomic sequences, gene Bs0711124 of the eubacterium Bacillus subtilis and other archaeal genes including lrs14 of Sulfolobus solfataricus have been identified as coding the N-terminal half of the feast/famine regulatory protein in the full-length (fl-FFRP). This half composes an independent domain, which is able to bind DNA. By comparing the amino acid sequences of the N-terminal DNA-binding domains of fl-FFRPs and of the newly identified group of half FFRPs, and by analyzing the 3D structures of fl-FFRPs previously reported, it has been predicted that the third α-helix in a domain of this type will recognize the nucleotide sequence by binding to DNA.
(Communicated by Masanori OTSUKA, M. J. A., March 12, 2003)