Sequence and analysis of chromosome 1 of the plant Arabidopsis thaliana

The genome of the flowering plant Arabidopsis thaliana has five chromosomes. Here we report the sequence of the largest, chromosome 1, in two contigs of around 14.2 and 14.6 megabases. The contigs extend from the telomeres to the centromeric borders, regions rich in transposons, retrotransposons and repetitive elements such as the 180-base-pair repeat. The chromosome represents 25% of the genome and contains about 6,850 open reading frames, 236 transfer RNAs (tRNAs) and 12 small nuclear RNAs. There are two clusters of tRNA genes at different places on the chromosome. One consists of 27 tRNA(Pro) genes and the other contains 27 tandem repeats of tRNA(Tyr)-tRNA(Tyr)-tRNA(Ser) genes. Chromosome 1 contains about 300 gene families with clustered duplications. There are also many repeat elements, representing 8% of the sequence.     

Censored distribution techniques in analysis of toxicological data

Zusammenfassung Es werden Methoden der Dosis-Effekt-Analyse verglichen, die es erlauben, nicht mehr gemessene Werte in höheren Dosisbereichen zu schätzen. Obwohl die Daten eng beieinander liegen, ergab die vonGupta ⁵ 1952 entwickelte Methode zur Bestimmung von Mittelwerten befriedigende Schätzungen, verifiziert durch die Übereinstimmung innerhalb der Gruppen.

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Supported by N.I.H. Grants No. FR-05526 and No. C-6516, and National Air Pollution Control Administration Contract, CPA 70-17.     

Cloning and structure of a yeast gene encoding a general transcription initiation factor TFIID that binds to the TATA box

The TATA sequence-binding factor TFIID plays a central role both in promoter activation by RNA polymerase II and other common initiation factors, and in promoter regulation by gene-specific factors. The sequence of yeast TFIID, which seems to be encoded by a single gene, contains interesting structural motifs that are possibly involved in these functions, and is similar to sequences of bacterial sigma factors.     

"起-停"巡航控制系统的纵向车距控制方法

针对单一设计距离控制中出现的速度滞后问题,综合考虑速度和距离的控制,提出了一种基于"起停"巡航控制系统的纵向车间距控制器设计方法。该控制器的设计中引入了控制因子,建立了兼顾速度和距离控制的目标性能函数,并对控制因子的取值作了讨论。通过理论分析和仿真实验表明,所提出的控制方法使速度滞后的问题得到改善,同时控制器对质量具有鲁棒性。     

CO2 regulator SLAC1 and its homologues are essential for anion homeostasis in plant cells

The continuing rise in atmospheric [CO2] is predicted to have diverse and dramatic effects on the productivity of agriculture, plant ecosystems and gas exchange. Stomatal pores in the epidermis provide gates for the exchange of CO2 and water between plants and the atmosphere, processes vital to plant life. Increased [CO2] has been shown to enhance anion channel activity proposed to mediate efflux of osmoregulatory anions (Cl- and malate(2-)) from guard cells during stomatal closure. However, the genes encoding anion efflux channels in plant plasma membranes remain unknown. Here we report the isolation of an Arabidopsis gene, SLAC1 (SLOW ANION CHANNEL-ASSOCIATED 1, At1g12480), which mediates CO2 sensitivity in regulation of plant gas exchange. The SLAC1 protein is a distant homologue of bacterial and fungal C4-dicarboxylate transporters, and is localized specifically to the plasma membrane of guard cells. It belongs to a protein family that in Arabidopsis consists of four structurally related members that are common in their plasma membrane localization, but show distinct tissue-specific expression patterns. The loss-of-function mutation in SLAC1 was accompanied by an over-accumulation of the osmoregulatory anions in guard cell protoplasts. Guard-cell-specific expression of SLAC1 or its family members resulted in restoration of the wild-type stomatal responses, including CO2 sensitivity, and also in the dissipation of the over-accumulated anions. These results suggest that SLAC1-family proteins have an evolutionarily conserved function that is required for the maintenance of organic/inorganic anion homeostasis on the cellular level.     

iPSC-derived neural precursor cells: potential for cell transplantation therapy in spinal cord injury

A number of studies have demonstrated that transplantation of neural precursor cells (NPCs) promotes functional recovery after spinal cord injury (SCI). However, the NPCs had been mostly harvested from embryonic stem cells or fetal tissue, raising the ethical concern. Yamanaka and his colleagues established induced pluripotent stem cells (iPSCs) which could be generated from somatic cells, and this innovative development has made rapid progression in the field of SCI regeneration. We and other groups succeeded in producing NPCs from iPSCs, and demonstrated beneficial effects after transplantation for animal models of SCI. In particular, efficacy of human iPSC–NPCs in non-human primate SCI models fostered momentum of clinical application for SCI patients. At the same time, however, artificial induction methods in iPSC technology created alternative issues including genetic and epigenetic abnormalities, and tumorigenicity after transplantation. To overcome these problems, it is critically important to select origins of somatic cells, use integration-free system during transfection of reprogramming factors, and thoroughly investigate the characteristics of iPSC–NPCs with respect to quality management. Moreover, since most of the previous studies have focused on subacute phase of SCI, establishment of effective NPC transplantation should be evaluated for chronic phase hereafter. Our group is currently preparing clinical-grade human iPSC–NPCs, and will move forward toward clinical study for subacute SCI patients soon in the near future.