Motoaki Seki

Bio: Motoaki Seki is an academic researcher from Kihara Institute for Biological Research. The author has contributed to research in topics: Arabidopsis & Gene. The author has an hindex of 96, co-authored 314 publications receiving 42940 citations. Previous affiliations of Motoaki Seki include Salk Institute for Biological Studies & Yokohama City University.

Monitoring the expression profiles of 7000 Arabidopsis genes under drought, cold and high-salinity stresses using a full-length cDNA microarray.

Abstract: Full-length cDNAs are essential for functional analysis of plant genes in the post-sequencing era of the Arabidopsis genome. Recently, cDNA microarray analysis has been developed for quantitative analysis of global and simultaneous analysis of expression profiles. We have prepared a full-length cDNA microarray containing approximately 7000 independent, full-length cDNA groups to analyse the expression profiles of genes under drought, cold (low temperature) and high-salinity stress conditions over time. The transcripts of 53, 277 and 194 genes increased after cold, drought and high-salinity treatments, respectively, more than fivefold compared with the control genes. We also identified many highly drought-, cold- or high-salinity- stress-inducible genes. However, we observed strong relationships in the expression of these stress-responsive genes based on Venn diagram analysis, and found 22 stress-inducible genes that responded to all three stresses. Several gene groups showing different expression profiles were identified by analysis of their expression patterns during stress-responsive gene induction. The cold-inducible genes were classified into at least two gene groups from their expression profiles. DREB1A was included in a group whose expression peaked at 2 h after cold treatment. Among the drought, cold or high-salinity stress-inducible genes identified, we found 40 transcription factor genes (corresponding to approximately 11% of all stress-inducible genes identified), suggesting that various transcriptional regulatory mechanisms function in the drought, cold or high-salinity stress signal transduction pathways.

Arabidopsis AtMYC2 (bHLH) and AtMYB2 (MYB) Function as Transcriptional Activators in Abscisic Acid Signaling

Abstract: In Arabidopsis, the induction of a dehydration-responsive gene, rd22, is mediated by abscisic acid (ABA). We reported previously that MYC and MYB recognition sites in the rd22 promoter region function as cis-acting elements in the drought- and ABA-induced gene expression of rd22. bHLH- and MYB-related transcription factors, rd22BP1 (renamed AtMYC2) and AtMYB2, interact specifically with the MYC and MYB recognition sites, respectively, in vitro and activate the transcription of the β-glucuronidase reporter gene driven by the MYC and MYB recognition sites in Arabidopsis leaf protoplasts. Here, we show that transgenic plants overexpressing AtMYC2 and/or AtMYB2 cDNAs have higher sensitivity to ABA. The ABA-induced gene expression of rd22 and AtADH1 was enhanced in these transgenic plants. Microarray analysis of the transgenic plants overexpressing both AtMYC2 and AtMYB2 cDNAs revealed that several ABA-inducible genes also are upregulated in the transgenic plants. By contrast, a Ds insertion mutant of the AtMYC2 gene was less sensitive to ABA and showed significantly decreased ABA-induced gene expression of rd22 and AtADH1. These results indicate that both AtMYC2 and AtMYB2 proteins function as transcriptional activators in ABA-inducible gene expression under drought stress in plants.

OsDREB genes in rice, Oryza sativa L., encode transcription activators that function in drought‐, high‐salt‐ and cold‐responsive gene expression

Abstract: Summary The transcription factors DREBs/CBFs specifically interact with the dehydration-responsive element/C-repeat (DRE/CRT) cis-acting element (core motif: G/ACCGAC) and control the expression of many stress-inducible genes in Arabidopsis. In rice, we isolated five cDNAs for DREB homologs: OsDREB1A, OsDREB1B, OsDREB1C, OsDREB1D, and OsDREB2A. Expression of OsDREB1A and OsDREB1B was induced by cold, whereas expression of OsDREB2A was induced by dehydration and high-salt stresses. The OsDREB1A and OsDREB2A proteins specifically bound to DRE and activated the transcription of the GUS reporter gene driven by DRE in rice protoplasts. Over-expression of OsDREB1A in transgenic Arabidopsis induced over-expression of target stress-inducible genes of Arabidopsis DREB1A resulting in plants with higher tolerance to drought, high-salt, and freezing stresses. This indicated that OsDREB1A has functional similarity to DREB1A. However, in microarray and RNA blot analyses, some stress-inducible target genes of the DREB1A proteins that have only ACCGAC as DRE were not over-expressed in the OsDREB1A transgenic Arabidopsis. The OsDREB1A protein bound to GCCGAC more preferentially than to ACCGAC whereas the DREB1A proteins bound to both GCCGAC and ACCGAC efficiently. The structures of DREB1-type ERF/AP2 domains in monocots are closely related to each other as compared with that in the dicots. OsDREB1A is potentially useful for producing transgenic monocots that are tolerant to drought, high-salt, and/or cold stresses.

Isolation and Functional Analysis of Arabidopsis Stress-Inducible NAC Transcription Factors That Bind to a Drought-Responsive cis-Element in the early responsive to dehydration stress 1 Promoter

Abstract: The MYC-like sequence CATGTG plays an important role in the dehydration-inducible expression of the Arabidopsis thaliana EARLY RESPONSIVE TO DEHYDRATION STRESS 1 (ERD1) gene, which encodes a ClpA (ATP binding subunit of the caseinolytic ATP-dependent protease) homologous protein. Using the yeast one-hybrid system, we isolated three cDNA clones encoding proteins that bind to the 63-bp promoter region of erd1, which contains the CATGTG motif. These three cDNA clones encode proteins named ANAC019, ANAC055, and ANAC072, which belong to the NAC transcription factor family. The NAC proteins bound specifically to the CATGTG motif both in vitro and in vivo and activated the transcription of a beta-glucuronidase (GUS) reporter gene driven by the 63-bp region containing the CATGTG motif in Arabidopsis T87 protoplasts. The expression of ANAC019, ANAC055, and ANAC072 was induced by drought, high salinity, and abscisic acid. A histochemical assay using P(NAC)-GUS fusion constructs showed that expression of the GUS reporter gene was localized mainly to the leaves of transgenic Arabidopsis plants. Using the yeast one-hybrid system, we determined the complete NAC recognition sequence, containing CATGT and harboring CACG as the core DNA binding site. Microarray analysis of transgenic plants overexpressing either ANAC019, ANAC055, or ANAC072 revealed that several stress-inducible genes were upregulated in the transgenic plants, and the plants showed significantly increased drought tolerance. However, erd1 was not upregulated in the transgenic plants. Other interacting factors may be necessary for the induction of erd1 in Arabidopsis under stress conditions.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

RNA-Seq: a revolutionary tool for transcriptomics

Abstract: RNA-Seq is a recently developed approach to transcriptome profiling that uses deep-sequencing technologies. Studies using this method have already altered our view of the extent and complexity of eukaryotic transcriptomes. RNA-Seq also provides a far more precise measurement of levels of transcripts and their isoforms than other methods. This article describes the RNA-Seq approach, the challenges associated with its application, and the advances made so far in characterizing several eukaryote transcriptomes.

Salt and drought stress signal transduction in plants

Abstract: Salt and drought stress signal transduction consists of ionic and osmotic homeostasis signaling pathways, detoxification (i.e., damage control and repair) response pathways, and pathways for growth regulation. The ionic aspect of salt stress is signaled via the SOS pathway where a calcium-responsive SOS3-SOS2 protein kinase complex controls the expression and activity of ion transporters such as SOS1. Osmotic stress activates several protein kinases including mitogen-activated kinases, which may mediate osmotic homeostasis and/or detoxification responses. A number of phospholipid systems are activated by osmotic stress, generating a diverse array of messenger molecules, some of which may function upstream of the osmotic stress-activated protein kinases. Abscisic acid biosynthesis is regulated by osmotic stress at multiple steps. Both ABA-dependent and -independent osmotic stress signaling first modify constitutively expressed transcription factors, leading to the expression of early response transcriptional activators, which then activate downstream stress tolerance effector genes.