Rangewide Genetic Diversity in Natural Populations of Chinese Pine (Pinus tabulaeformis)

Thirteen natural populations from throughout the range of the Chinese pine (Pinus tabulaeformis Carr.) were examined using inter-simple sequence repeat markers to characterize the genetic structure at the species level and to compare the extent and distribution of genetic variation among central, intermediate, and marginal populations. Although the total genetic variation in the Chinese pine was mainly maintained within populations, the genetic differentiation among populations was significant (P < 0.001). The genetic divergence was significantly correlated with geographic distance (P < 0.05). Genetic diversity tended to decrease from the central to intermediate and marginal populations. The marginal populations had significantly lower intrapopulation genetic diversity than central populations (P < 0.05). Cluster analysis based on Nei’s unbiased genetic distances confirmed the difference among four central populations and the rest. Both historical and contemporary factors may have played key roles in shaping the spatial genetic structure of this species.     

Human acyl-coenzyme A:cholesterol acyltransferase 1 (acat1) sequences located in two different chromosomes (7 and 1) are required to produce a novel ACAT1 isoenzyme with additional sequence at the N terminus

A rare form of human ACAT1 mRNA, containing the optional long 5'-untranslated region, is produced as a 4.3-kelonucleotide chimeric mRNA through a novel interchromosomal trans-splicing of two discontinuous RNAs transcribed from chromosomes 1 and 7. To investigate its function, we express the chimeric ACAT1 mRNA in Chinese hamster ovary cells and show that it can produce a larger ACAT1 protein, with an apparent molecular mass of 56 kDa on SDS-PAGE, in addition to the normal, 50-kDa ACAT1 protein, which is produced from the ACAT1 mRNAs without the optional long 5'-untranslated repeat. To produce the 56-kDa ACAT1, acat1 sequences located at both chromosomes 7 and 1 are required. The 56-kDa ACAT1 can be recognized by specific antibodies prepared against the predicted additional amino acid sequence located upstream of the N-terminal of the ACAT1(ORF). The translation initiation codon for the 56-kDa protein is GGC, which encodes for glycine, as deduced by mutation analysis and mass spectrometry. Similar to the 50-kDa protein, when expressed alone, the 56-kDa ACAT1 is located in the endoplasmic reticulum and is enzymatically active. The 56-kDa ACAT1 is present in native human cells, including human monocyte-derived macrophages. Our current results show that the function of the chimeric ACAT1 mRNA is to increase the ACAT enzyme diversity by producing a novel isoenzyme. To our knowledge, our result provides the first mammalian example that a trans-spliced mRNA produces a functional protein.     

ChAy/Bx, a novel chimeric high-molecular-weight glutenin subunit gene apparently created by homoeologous recombination in Triticum turgidum ssp. dicoccoides

High-molecular-weight glutenin subunits (HMW-GSs) are of considerable interest, because they play a crucial role in determining dough viscoelastic properties and end-use quality of wheat flour. In this paper, ChAy/Bx, a novel chimeric HMW-GS gene from Triticum turgidum ssp. dicoccoides (AABB, 2n = 4x = 28) accession D129, was isolated and characterized. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed that the electrophoretic mobility of the glutenin subunit encoded by ChAy/Bx was slightly faster than that of 1Dy12. The complete ORF of ChAy/Bx contained 1671 bp encoding a deduced polypeptide of 555 amino acid residues (or 534 amino acid residues for the mature protein), making it the smallest HMW-GS gene known from Triticum species. Sequence analysis showed that ChAy/Bx was neither a conventional x-type nor a conventional y-type subunit gene, but a novel chimeric gene. Its first 1305 nt sequence was highly homologous with the corresponding sequence of 1Ay type genes, while its final 366 nt sequence was highly homologous with the corresponding sequence of 1Bx type genes. The mature ChAy/Bx protein consisted of the N-terminus of 1Ay type subunit (the first 414 amino acid residues) and the C-terminus of 1Bx type subunit (the final 120 amino acid residues). Secondary structure prediction showed that ChAy/Bx contained some domains of 1Ay subunit and some domains of 1Bx subunit. The special structure of this HMW glutenin chimera ChAy/Bx subunit might have unique effects on the end-use quality of wheat flour. Here we propose that homoeologous recombination might be a novel pathway for allelic variation or molecular evolution of HMW-GSs.     

Molecular characterization and expression analysis on two isogenes encoding 3-deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-<Emphasis Type="Italic">arabino</Emphasis>-heptulosonate 7-phosphate synthase in grapes

3-Deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAHPS) is an entry enzyme of the shikimate pathway that connects primary carbohydrate metabolism with the biosynthesis of most secondary metabolites in plants. In the present study, two DAHPS cDNAs were cloned from grape berries (Vitis vinifera) and designated as VvDAHPS-1 and VvDAHPS-2. These two cDNA sequences share 75.7% of the identities. Their DNA corresponding to the two isogenes both contain four introns. The deduced proteins from two cDNAs had different NH₄-terminal regions and putative mature regions sharing sequence, molecular size and pI value similarity. Both of VvDAHPSs had a close evolution relationship with Populus trichocarpa DAHPSs. The prokaryotically-expressed VvDAHPSs both manifested DAHPS catalytic activity and Mn²⁺-activated effects. Analysis by real time-PCR showed that VvDAHPS-1 and VvDAHPS-2 were expressed in all the tested tissues, but their expression patterns accompanying with berry mature varied in the skin, pulp and seeds. The results give new insight into further study on regulatory mechanism of grape phenolics biosynthesis.     

不同抽薹性不结球白菜抽薹过程中碳氮指标的分析

以抽薹性不同的不结球白菜自交系为材料,研究了抽薹前后6个发育阶段叶片中碳水化合物、可溶性蛋白质、游离氨基酸含量的变化。结果表明,可溶性总糖、蔗糖、淀粉含量在花芽分化时不断升高,分化完成后下降,抽薹时又有所升高;还原糖仅在花芽分化中期升高;三个自交系相比,晚抽薹自交系08-1P-89在花芽分化时糖含量最高;可溶性蛋白质和游离氨基酸变化趋势与可溶性总糖基本一致,但游离氨基酸含量在抽薹时明显下降,整个过程中晚抽薹自交系含量都最高;在花芽分化过程和抽薹期,碳氮比呈升高趋势。     

Novel antiphytopathogenic compound 2-heptyl-5-hexylfuran-3-carboxylic acid, produced by newly isolated Pseudomonas sp. strain SJT25

Pseudomonas sp. strain SJT25, which strongly antagonizes plant pathogens, was isolated from rice rhizosphere soil by a bioactivity-guided approach. A novel antiphytopathogenic compound was isolated from the fermentation broth of Pseudomonas sp. SJT25 and identified as 2-heptyl-5-hexylfuran-3-carboxylic acid. This compound showed antimicrobial activities both in vitro and in vivo.     

响应面法优化黑水虻幼虫蛋白质提取工艺

【目的】对黑水虻Hermetia illucens幼虫蛋白质进行不同提取方法的比较,选择最优提取方法,并确定其最优工艺参数,为黑水虻幼虫蛋白提取与资源利用提供依据。【方法】以黑水虻幼虫为原料,分别采用碱提法、酶提法、盐提法和Tris-HCl缓冲液提法对黑水虻幼虫蛋白质进行提取,并比较分析。通过单因素试验分别确定NaOH质量浓度、液料比、提取温度及提取时间4个因素的较优水平。在单因素试验结果基础上,按照Box-Behnken响应面试验设计进行响应面优化试验。【结果】提取黑水虻幼虫蛋白质的4种方法中碱提法的提取率最高,最佳提取条件为：NaOH质量浓度2.44 g/100mL,液料比22 mL/g,提取温度53℃,提取时间2 h。提取率验证试验结果为88.49%,与预测值相对误差为0.28%。【结论】响应面模型拟合度高,优化出的最佳提取工艺可行。     

黏着斑激酶的结构与功能

黏着斑激酶(focal adhesion kinase,FAK)是细胞内一种重要的信号转导分子,参与多条重要信号通路和多种细胞生物学行为的调控。该文结合当前的研究进展,总结了FAK通过其复杂的信号转导通路在细胞迁徙、增殖、抗凋亡方面的功能,并简要归纳了FAK与肿瘤之间的密切联系。