Molecular cloning and expression analysis of <Emphasis Type="Italic">Bmrbp1</Emphasis>, the <Emphasis Type="Italic">Bombyx mori</Emphasis> homologue of the <Emphasis Type="Italic">Drosophila</Emphasis> gene <Emphasis Type="Italic">rbp1</Emphasis>

RBP1 is an important splicing factor involved in alternative splicing of the pre-mRNA of Drosophila sex-determining gene dsx. In this work, the Bombyx mori homologue of the rbp1 gene, Bmrbp1, was cloned. The pre-mRNA of Bmrbp1 gene is alternatively spliced to produce four mature mRNAs, named Bmrbp1-PA, Bmrbp1-PB, Bmrbp1-PC and Bmrbp1-PD, with nucleotide lengths of 799 nt, 1,316 nt, 894 nt and 724 nt, coding for 142 aa, 159 aa, 91 aa and 117 aa, respectively. BmRBP1-PA and BmRBP1-PD contain a N terminal RNA recognization motif (RRM) and a C terminal arginine/serine-rich domain, while BmRBP1-PB and BmRBP1-PC only share a RRM. Amino acid sequence alignments showed that BmRBP1 is conserved with its homologues in other insects and with other SR family proteins. The RT-PCR showed that Bmrbp1-PA was strongly expressed in all examined tissues and development stages, but Bmrbp1-PB was weakly expressed in these tissues and stages. The expression of both Bmrbp1-PA and Bmrbp1-PB showed no obvious sex difference. While the Bmrbp1-PC and Bmrbp1-PD were beyond detection by RT-PCR very likely due to their tissue/stage specificity. These results suggested that Bmrbp1 should be a member of SR family splicing factors, whether it is involved in the sex-specific splicing of Bmdsx pre-mRNA needs further research.     

Proliferation, multipotency and neuronal differentiation of cryopreserved neural progenitor cells derived from the olfactory neuroepithelium of the adult rat

The use of olfactory neuroepithelium neural progenitor cells for transplantation has attracted attention in the treatment of many neurological disorders, which require efficient recovery methods and cryopreservation procedures. The purpose of this study was to evaluate different cryopreservation techniques for neural progenitor cells derived from the olfactory neuroepithelium (ONe NPCs) in adult rats. Initially, we compared the survival rates of cryopreserved ONe NPCs treated with six different cryoprotectants: dimethylsulfoxide (DMSO), ethylene glycol (EG) and glycerol, each with or without 10% FBS and with two different storage periods in liquid nitrogen (-196 degrees C), specifically 3 days short-term storage and 3 months long-term storage. We assessed the recovery efficiency of ONe NPCs after freezing and thawing by viability testing and colony-forming assay as well as immunocytochemistry under different conditions. No significant difference in the survival rate was observed among these different cryoprotectants. With these protocols, ONe NPCs retained their multipotency and differentiated into glial (GFAP-positive), neuronal (NeuN-positive) and oligodendroglia (Galc-positive) cells. Collectively, our results imply that, under optimal conditions, ONe NPCs might be cryopreserved for periods of >3 months without losing their proliferative and multipotency activities.     

密度制约对宝天曼落叶阔叶林锐齿栎死亡前后分布格局的影响

为了在温带和亚热带的过渡带中验证森林树木死亡是否受密度制约的影响, 我们在宝天曼国家级自然保护区选择1个100 m×100 m的暖温带落叶阔叶林样地, 用双变量函数g(r)(the pair-correlation function)研究了锐齿栎(Quercus aliena var. acuteserrata)死亡前(活树和枯木统称为死亡前树木)和死亡后(活树为死亡后树木)的分布格局。把样地中的锐齿栎分为幼树(1 cm ≤ DBH<10 cm)、小树(10 cm ≤ DBH<20 cm)和成年树(DBH≥20 cm)3个不同的生长阶段来研究密度制约对空间分布格局的影响机制。结果表明: (1)死亡前锐齿栎在r>5 m尺度呈聚集分布, 死亡后幼树(1 cm≤DBH<10 cm)和成年树(DBH≥20 cm)在1-25 m尺度呈现随机分布, 死亡后小树(10 cm≤DBH< 20 cm)在r<1.5 m和2.5-4.5 m的尺度为随机分布, 在r>5 m的尺度呈聚集分布; (2)采用随机标签零模型和案例-对照设计的方法, 排除生境异质性影响后, 将幼树和小树的分布格局作为案例, 将成年树的分布格局作为对照, 并代表生境异质性的作用, 通过小径级树木与成年树分布格局的对比发现, 密度制约效应对死亡前后的锐齿栎分布格局均具有影响; (3)幼树和小树在成年树周围的分布死亡前为显著聚集分布格局, 死亡后剩余树木的聚集强度下降; 随着与成年树之间距离的增加, 死亡后的幼树(仅包括现存的活树)逐渐向随机分布格局演替。本研究初步表明锐齿栎空间格局受生境异质性的影响并呈现出显著的聚集效应, 排除生境异质性影响后, 锐齿栎死亡前后的空间格局受到密度制约的影响, 这一结果为Janzen-Connell假说提供了支持。     

N-arylaminonitriles as bioavailable peptidomimetic inhibitors of cathepsin B

To improve the pharmacokinetics of a previously reported series of dipeptidyl nitrile cathepsin B inhibitors, the P(2)-P(3) amide group was replaced with an arylamine. Further optimization of this template resulted in highly potent and selective inhibitors with excellent oral availability.     

Mining single nucleotide polymorphisms from EST data of silkworm, Bombyx mori, inbred strain Dazao

We made use of 81,635 expressed sequence tags (ESTs) derived from 12 different cDNA libraries of the silkworm, Bombyx mori, inbred strain Dazao (P50), to identify high-quality candidate single nucleotide polymorphisms (SNPs). By PHRAP assembling, 12,980 contigs containing 11,537 contigs assembled by more than one read were obtained, and 101 candidate SNPs and 27 single base insertions/deletions were identified from 117 contigs assembled from 1576 high-quality reads base-called with PHRED and screened on the basis of the neighborhood quality standard (NQS). Simultaneously, we also predicted 40 SNPs in coding regions (cSNPs), of which 26 were predicted to lead to amino acid non-synonymous variations and 14 synonymous substitutions. Also, the 1.66:1 ratio of transition/transversion is different from that of other insects. As the first SNP analysis of a Lepidoptera, B. mori, the single nucleotide polymorphic density is estimated to be 1.3 x 10(-3) by sequence diversity. This analysis shows that expressed sequences from multiple libraries may provide an abundant source of comparative reads to mine for cSNPs from the silkworm genome.     

Docking-assisted 3D-QSAR studies on xanthones as <Emphasis Type="Italic">α</Emphasis>-glucosidase inhibitors

Recently, a series of xanthone analogues has been identified as α-glucosidase inhibitors. To provide deeper insight into the three-dimensional (3D) structural requirements for the activities of these molecules, CoMFA and CoMSIA approaches were employed on 54 xanthones to construct 3D-QSAR models. Their bioactive conformations were first investigated by docking studies and optimized by subsequent molecular dynamics (MD) simulations using the homology modeled structure of the target protein. Based on the docking/MD-determined conformers, 3D-QSAR studies generated several significant models in terms of 47 molecules as the training set. The best model (CoMSIA-SHA) yielded q ² of 0.713, r ² of 0.967 and F of 140.250. The robustness of the model was further externally confirmed by a test set of the remaining molecules (q ² = 0.793, r ² = 0.902, and k = 0.905). Contour maps provided much information for future design and optimization of new compounds with high inhibitory activities towards α-glucosidase.

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Graphical Abstract CoMSIA/SHA contour map of xanthone α-glucosidase inhibitor