Mouse Nif3l1 gene is highly conserved from bacteria to human. Even though this gene is expressed throughout embryonic development, its biological function is still obscure. Here, we show that Nif3l1 participates in retinoic acid-primed neural differentiation of P19 embryonic carcinoma cells through cooperation with Trip15/CSN2, a transcriptional corepressor/component of COP9 signalosome. We isolated Nif3l1 cDNA from P19 cell cDNA library by a yeast two-hybrid screening using Trip15/CSN2 as a bait. This interaction was confirmed by a pull-down assay and an epitope-tagged coimmunoprecipitation. Although Nif3l1 was mainly detected in the cytoplasm, the translocation of Nif3l1 into the nuclei was observed in retinoic acid-primed neural differentiation of P19 cells and enhanced by the enforced expression of Trip15/CSN2. Furthermore, enforced expression of sense Nif3l1 RNA, but not antisense RNA, enhanced the neural differentiation of P19 cells accompanying the intense down-regulation of Oct-3/4 mRNA expression and the rapid induction of Mash-1 mRNA expression. Luciferase reporter assay showed that Nif3l1 could act as a transcriptional repressor and synergized the transcriptional repression by Trip15/CSN2. These results indicate that Nif3l1 implicates in neural differentiation through the cooperation with Trip15/CSN2.

In the MUCES-C mission conducted by JAXA (Japan Aero Exploration Agency), a microwave neutralizer is mounted with a microwave ion engine on the HAYABUSA space probe. The neutralizer consists of an L-shaped antenna to inject microwaves and samarium cobalt magnets to provide ECR (electron cyclotron resonance). Plasma production of a higher density than the cutoff density is expected in the discharge chamber, but the neutralizer is so small that high-precision measurements using a probe are difficult. To clarify the plasma production mechanism in the microwave neutralizer, numerical analysis was conducted using a code coupling PIC (particle-in-cell) method, and a FDTD (finitedifference-time-domain) method. This paper describes effects caused by varying magnetic field configuration and antenna position in the neutralizer. The calculation results show that bringing the antenna closer to the ECR region is effective for plasma production.

Karyotypes and chromosome pairings were investigated in the triploid hybrid (2 n= 24) between the tetraploid Allium wakegi and A. ascalonicum and in the triploid hybrid (2n=24) between the tetraploid A. wakegi and A. fistulosum. In the somatic chromosome complements of both triploid hybrids 8 pairs of chromosomes and 8 single chromosomes could be morphologically distinguished, and the karyotypes were respectively expressed by the following formulas : K(2n)=2 (7V+J()) +(7V±J2), K(2n)=(?V+Ji)+2(7V+J2). At metaphase-I in the pollen mother cells of both triploid hybrids, 8 bivalents and 8 univalents were regularly formed. The members of morphological pairs in the somatic chromosome complements and bivalents in the meiotic cells were relatively large in the hybrid between the tetraploid A. wakegi and A. ascalonicum, while relatively small in the hybrid between the tetraploid A. wakegi and A. fistulosum. Moreover, the meiotic behaviors of the triploid hybrids were quite similar to those of the first backcrosses of amphidiploid hybrids between A. ascalonicum and A. fistulosum. From these results it can be concluded that A. wakegi is an allodiploid plant and has 2 component genomes, one of which is homologous with the genome of A. ascalonicum and the other with the genome of A. fistulosum.

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