Asymmetric synthesis of β-amino alcohol by reductive cross-coupling of planar chiral ferrocenecarboxaldehyde with N-tosyl ferrocenylideneamine, and its application to asymmetric reaction

Samarium iodine-mediated cross-coupling of N-tosyl ferrocenylideneamine with planar chiral ferrocenecarboxaldehyde gave diastereoselectively anti-β-amino alcohol derivative in good yield. The obtained anti-β-amino alcohol with ferrocene ring at 1,2-positions was utilized as chiral auxiliary for asymmetric alkylation and acylation reactions.     

Population Structures in Rhododendron metternichii var. hondoense Assessed with Microsatellites and their Implication for Conservation

Rhododendron metternichii var. hondoense is its great morphological variation. Individuals may have only one erect stem or may have multiple creeping stems, implying that some of them recruit vegetatively. Aims of this study are to ascertain whether a population of R. metternichii var. hondoense consists of clonal plants, and to evaluate relative importance of sexual and asexual recruitments in regard to its conservation. Six microsatellite loci were analyzed in two populations growing in different habitats. One was in a mesic valley consisting of many sprouting and creeping individuals with few seedlings, and the other on a mountain ridge consisting of single stem individuals with many seedlings. Sufficient polymorphisms were found to be present even in the mesic valley population that consisted of many sprouting and creeping stems, indicating that in the past the population was maintained by both sexual and asexual reproduction. The scarcity of seedlings at the mesic valley was due to dense litter cover and low bryophyte mat cover which may be caused by changes in traditional management systems. Required conservation measures are discussed based on these results. Received 8 July 1999/ Accepted in revised form 26 August 1999     

Expansion of bamboo forests caused by reduced bamboo-shoot harvest under different natural and artificial conditions

To elucidate the expansion of bamboo (Phyllostachys pubescens Mazel ex Houzeau de Lehaie) forests, we used multiple linear regression analysis and determined whether there were site differences for data obtained in Hirasawa, Otaki-machi, Chiba Prefecture, and Kofuki, Takehara City, Hiroshima Prefecture, Japan. Vegetation maps from 1984 and 2001 for Hirasawa, and from 1986, 1996, 2000, and 2006 for Kofuki, were compared, and the annual expansion rate of each P. pubescens forest was calculated. We evaluated nine indices, including original bamboo forest area, neighbouring vegetation, slope inclination and aspect, distance from roads, and shipment of bamboo shoots. Shipment of bamboo shoots was a positive factor for P. pubescens forest expansion, whereas the proportion of adjacent short vegetation, northness (the cosine of slope aspect), and area negatively affected the expansion in Hirasawa (R ² = 0.683). On the other hand, distance from roads and eastness (the sine of slope aspect) positively affected expansion, while slope inclination was a negative factor in Kofuki (R ² = 0.942). We calculated that P. pubescens forests expanded at about 2% per year in regions of reduced shipments of bamboo-shoot harvest. We showed that not only natural conditions but also management factors affect P. pubescens forest expansion. Regional differences in natural and anthropogenic effects on expansion were also found.     

内蒙古典型草原生态系统健康评价

以草原生态系统中的植物-土壤-大气界面的关键生态过程为基础,结合典型草原生态系统的群落特征及其退化演替模式,并考虑水分因子的限制作用,在确定生态系统健康评价模式(参照)系统和基况评价指标的同时,建立了典型草原生态系统健康评价的CVOR综合指数的计算模型和方法.通过分析放牧压力和围封保育对内蒙古典型草原生态系统健康的影响,检验了CVOR综合指数的可行性,可为草原生态系统健康管理提供一个综合、简单、准确、宜行的评价方法.     

Structural basis for the interaction between the first SURP domain of the SF3A1 subunit in U2 snRNP and the human splicing factor SF1

SURP domains are exclusively found in splicing‐related proteins in all eukaryotes. SF3A1, a component of the U2 snRNP, has two tandem SURP domains, SURP1, and SURP2. SURP2 is permanently associated with a specific short region of SF3A3 within the SF3A protein complex whereas, SURP1 binds to the splicing factor SF1 for recruitment of U2 snRNP to the early spliceosomal complex, from which SF1 is dissociated during complex conversion. Here, we determined the solution structure of the complex of SURP1 and the human SF1 fragment using nuclear magnetic resonance (NMR) methods. SURP1 adopts the canonical topology of α1–α2–3₁₀–α3, in which α1 and α2 are connected by a single glycine residue in a particular backbone conformation, allowing the two α‐helices to be fixed at an acute angle. A hydrophobic patch, which is part of the characteristic surface formed by α1 and α2, specifically contacts a hydrophobic cluster on a 16‐residue α‐helix of the SF1 fragment. Furthermore, whereas only hydrophobic interactions occurred between SURP2 and the SF3A3 fragment, several salt bridges and hydrogen bonds were found between the residues of SURP1 and the SF1 fragment. This finding was confirmed through mutational studies using bio‐layer interferometry. The study also revealed that the dissociation constant between SURP1 and the SF1 fragment peptide was approximately 20 μM, indicating a weak or transient interaction. Collectively, these results indicate that the interplay between U2 snRNP and SF1 involves a transient interaction of SURP1, and this transient interaction appears to be common to most SURP domains, except for SURP2.     

Pine forest structure in a human-dominated landscape system in Korea

To elucidate the characteristics of spatial heterogeneity in a human-dominated landscape, vegetation and community structure of pine (Pinus densiflora andP. rigida) forests were studied at rural Teokseong-ri in Chollanam-do, in the southwestern part of Korea. Daily removal of undergrowth for firewood affects the stratification and species composition in the community. In general, stratification of the pine forest develops in proportion to its distance from the main habitat of farmers, involving the residential and cultivated land. In pine forests near the main habitat of farmers, sun-demanding herbaceous plants grow well, while in remote forests, Fagaceous plants such asQuercus serrata, Q. actissima andCastanea crenata grow well. This zonation results from the fact that removal of undergrowth is greater in the forest near the main habitat of farmers, than in the remote forest. Construction and maintenance of graveyards, however, prevents development of stratification of the forest even in remote stands.     

Infection of turnip and radish storage roots with Agrobacterium rhizogenes

Within about 10 days after inoculation with Agrobacterium rhizogenes, the vascular bundles of storage root disks of turnip or radish developed small outgrowths with numerous root hairs. Thereafter, adventitious roots (hairy roots) emerged extensively from these outgrowths. The hairy roots which emerged fully supported the growth of host plants, though they lacked geotropism. An excised hairy root could be subcultured as an axenic root culture in the absence of phytohormones. Hairy root cultures with extensive lateral branches grew much more rapidly than those with few lateral branches or ordinary roots. Calli were induced from hairy root cultures in the presence of 2,4-D, and root proliferation from these calli occurred in the absence of 2,4-D. Both the primary hairy roots and the roots which grew from them synthesized agropine and mannopine.     

Cutting edge: double-stranded DNA breaks in the IgV region gene were detected at lower frequency in affinity-maturation impeded GANP-/- mice

Double-stranded DNA breaks (DSBs) at the IgV region (IgV) genes might be involved in somatic hypermutation and affinity-maturation of the B cell receptor in response to T cell-dependent Ag. By ligation-mediated PCR, we studied IgV DSBs that occurred in mature germinal center B cells in response to nitrophenyl-chicken gamma-globulin in a RAG1-independent, Ag-dependent, and IgV-selective manner. We quantified their levels in GANP-deficient B cells that have impaired generation of high-affinity Ab. GANP-/- B cells showed a decreased level of DSBs with blunt ends than control B cells and, on the contrary, the ganp gene transgenic (GANPTg) B cells showed an increased level. These results suggested that the level of IgV DSBs in germinal center B cells is associated with GANP expression, which is presumably required for B cell receptor affinity maturation.     

Peritoneal injection of fucoidan suppresses the increase of plasma IgE induced by OVA-sensitization

We previously reported that fucoidan, a dietary fiber purified from seaweed, inhibited IgE production by B cells in vitro. In this study, we examined the effect of fucoidan on IgE production in vivo. The OVA-induced increase of plasma IgE was significantly suppressed when fucoidan was intraperitoneally, but not orally, administered prior to the first immunization with OVA. The production of IL-4 and IFN-γ in response to OVA in spleen cells isolated from OVA-sensitized mice treated with fucoidan in vivo was lower than that from mice treated without fucoidan. Moreover, the flow cytometric analysis and ELISpot assay revealed that the administration of fucoidan suppressed a number of IgE-expressing and IgE-secreting B cells, respectively. These results indicate that fucoidan inhibits the increase of plasma IgE through the suppression of IgE-producing B cell population, and the effect of fucoidan in vivo is crucially dependent on the route and timing of its administration.     

Solution Structure of the Catalytic Domain of the Mitochondrial Protein ICT1 That Is Essential for Cell Vitality

The ICT1 protein was recently reported to be a component of the human mitoribosome and to have codon-independent peptidyl-tRNA hydrolysis activity via its conserved GGQ motif, although little is known about the detailed mechanism. Here, using NMR spectroscopy, we determined the solution structure of the catalytic domain of the mouse ICT1 protein that lacks an N-terminal mitochondrial targeting signal and an unstructured C-terminal basic-residue-rich extension, and we examined the effect of ICT1 knockdown (mediated by small interfering RNA) on mitochondria in HeLa cells using flow cytometry. The catalytic domain comprising residues 69-162 of the 206-residue full-length protein forms a structure with a β1-β2-α1-β3-α2 topology and a structural framework that resembles the structure of GGQ-containing domain 3 of class 1 release factors (RFs). Half of the structure, including the GGQ-containing loop, has essentially the same sequence and structure as those in RFs, consistent with the peptidyl-tRNA hydrolysis activity of ICT1 on the mitoribosome, which is analogous to RFs. However, the other half of the structure differs in shape from the corresponding part of RF domain 3 in that in ICT1, an α-helix (α1), instead of a β-turn, is inserted between strand β2 and strand β3. A characteristic groove formed between α1 and the three-stranded antiparallel β-sheet was identified as a putative ICT1-specific functional site by a structure-based alignment. In addition, the structured domain that recognizes stop codons in RFs is replaced in ICT1 by a C-terminal basic-residue-rich extension. It appears that these differences are linked to a specific function of ICT1 other than the translation termination mediated by RFs. Flow cytometry analysis showed that the knockdown of ICT1 results in apoptotic cell death with a decrease in mitochondrial membrane potential and mass. In addition, cytochrome c oxidase activity in ICT1 knockdown cells was decreased by 35% compared to that in control cells. These results indicate that ICT1 function is essential for cell vitality and mitochondrial function.