Cytokinins are a class of phytohormones involved in various physiological events of plants. The Arabidopsis sensor histidine kinase CRE1 was recently reported to be a cytokinin receptor. We used a steroid-inducible system to show that the transcription factor-type response regulator ARR1 directs transcriptional activation of the ARR6 gene, which responds to cytokinins without de novo protein synthesis. This fact, together with characteristics of ARR1-overexpressing plants and arr1 mutant plants, indicates that the phosphorelay to ARR1, probably from CRE1, constitutes an intracellular signal transduction occurring immediately after cytokinin perception.

The genes coding for the response regulators ARR1 and ARR2 have previously been identified by in silico screening of an expression sequence tag database and subsequent cloning from both Arabidopsis cDNA and genomic libraries. Their structures, in which the N-terminal signal receiver domain is followed by the output domain, are characteristic of typical bacterial response regulators of the two-component regulatory systems that control responses to a variety of environmental stimuli. Here we present evidence that these response regulators actually work as transcription factors. ARR1 and ARR2 were localized in the nuclei of plant cells regardless of the presence or absence of their signal receiver domain. Their middle segments, which faintly resemble the mammalian oncogene product Myb, were capable of binding double-stranded DNA in a sequence-specific manner in vitro. Their C-terminal halves functioned as transactivation domains in plant cells when combined with the DNA-binding domain of yeast GAL4. They thus possess all the essential components of a transcriptional activator. Both ARR1 and ARR2 promoted expression of a reporter gene in plant cells through their own target sequence. Truncation of their N-terminal signal receiver domain led to an increase in transactivation. An as yet unidentified phospho-relay signal may modulate the capability for transactivation and/or DNA binding through the signal receiver domain.

In order to upgrade the genome sequence information of J. curcas L., we integrated de novo assembly of a total of 537 million paired-end reads generated from the Illumina sequencing platform into the current genome assembly which was obtained by a combination of the conventional Sanger method and the Roche/454 sequencing platform. e total length of the upgraded genome sequences thus obtained was 297,661,187 bp consisting of 39,277 contigs. e average and N50 lengths of the generated contigs were 7,579 bp and 15,950 bp, both of which were increased fourfold from the previous genome assembly. Along with genome sequence upgrading, the currently available transcriptome data were collected from the public databases and assembled into 19,454 tentative consensus sequences. Based on a comparison between these tentative consensus sequences of transcripts and the predictions of computer programs, a total of 30,203 complete and partial structures of protein-encoding genes were deduced. e number of genes with complete structures was increased about threefold from the previous genome annotation. By applying the upgraded genome sequence and predicted proteincoding gene information, the number and features of the tandemly arrayed genes, syntenic relations between Jatropha and other plant genomes, and structural features of transposable elements were investigated. e detailed information on the updated J. curcas genome is available at http://www.kazusa.or.jp/jatropha/. Key words:Jatropha curcas, genome sequencing, transcriptome sequences, tentative consensus sequence, tandem gene duplication, database.Jatropha curcas L. is a perennial small tree or large shrub that belongs to the Euphorbiaceae family. J. curcas is endemic to central America but is distributed throughout the tropics and subtropics of Asia and Africa. J. curcas is an important non-edible oilseed crop with great potential for the production of biodiesel fuel. Since J. curcas is an undomesticated plant, its positive attributes in terms of breeding and utilization are not fully understood.In order to accelerate its genetic improvement, it is desirable to understand the genome information of J. curcas. With this goal in mind, we have analyzed the genome sequence of J. curcas by applying combined sequencing methods, and have made the obtained sequence information available through the public and web databases.e accumulated genome information (JAT_r3.0) was 285,858,490 bp consisting of 120,586 contigs and 29,831 singlets, and this accounted for approximately 95% of the gene-containing regions. A total of 40,929 complete and partial structures of proteinencoding genes have been deduced on the accumulated genome sequences. However, the majority of the predicted genes were partially predicted ones as the contig lengths were relatively short in JAT_r3.0. Further improvement of the genome sequence information is therefore needed.Along with the genome sequence approach, several transcriptome analyses have been attempted. Natarajan et al. have reported 12,084 ESTs using...

In order to investigate the clinical significance of redundant nerve roots of the cauda equina (RNR) and their pathogenesis, the following studies were performed: 1) examination of 1,256 myelograms of patients with lumbar disease; 2) clinical analysis of 55 patients with RNR and 75 without RNR; 3) electrophysiological examination of 9 patients with RNR; and 4) anatomical and histopathological examination of 6 autopsy cases. RNR were found in 42% of patients with severely constricted spinal canals. In comparing patients with RNR and those without RNR, RNR were found in older patients, these patients exhibited a longer period from the onset of the symptoms to the time of myelographic manifestation, and they caused more severe signs and symptoms. The spatial distribution of redundant nerve roots and the extent of degeneration of nerve fibers in redundant nerve roots indicated the close causal relationship between RNR and constriction of the spinal canal. As the pathogenesis of RNR, the authors suggest a squeezing force from the constricted spinal canal acting on the nerve roots.

An expression sequence tag database of higher plants was screened by in silico profile analysis for response regulators of the two-component regulatory system. Two closely related clones (ARR1 and ARR2), corresponding to one of the extracted candidates, were isolated from Arabidopsis thaliana. The two genes were comparably expressed in all tissues, and at higher levels in the roots. The amino-terminal half of their translation products was highly conserved. This is where a phosphate receiver domain with the landmark aspartate residue and a putative DNA-binding domain were located. Their carboxyl-terminal halves, although less similar to each other, included glutamine-rich and proline-rich regions characteristic of the transcriptional activation domain of eukaryotes. This architecture resembles that of typical bacterial response regulators serving as transcription factors.