Penicillium janthinellum菌株GXCR对Cu,Al和Zn的抗性特征及其Cu的生物矿化作用

对分离到的一株高抗Cu(200 mm ol/L CuSO4.5H2O)的P en icillium janth inellum菌株GXCR(中国微生物菌种保藏管理委员会普通微生物中心保藏号:CGM CC 1027)进行紫外诱变,获得了3株Cu抗性下降突变体,进一步测定结果表明,3个突变体对A l[A l2(SO4)3]和Zn(ZnSO4.7H2O)的抗性也显著下降;只有在含Cu的PDA上生长的菌体表面能够形成CuSO4.5H2O样的蓝色晶体。进一步的X-ray衍射的原子微量分析表明,这种蓝色晶体含Cu2 ,说明该菌具有Cu的生物矿化作用。菌体表面积累的Cu2 的量与菌株的抗Cu水平有正相关性,说明该菌对Cu的抗性很可能与Cu矿化作用有关。     

Structure and possible function of <Emphasis Type="Italic">N</Emphasis>-glycans of an invertebrate C-type lectin from the acorn barnacle <Emphasis Type="Italic">megabalanus rosa</Emphasis>

ABSTRACT:   A C-type lectin (BRA-2) isolated from the acorn barnacle Megabalanus rosa , which was a glycoprotein having an N -linked sugar chain, was deglycosylated by N -glycopeptidase F. The structure of the released sugar chains was determined by a 2-D mapping method after derivatization with a fluorescent reagent, 2-aminopyridine, to be Manα1-6(Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc and Manα1-6(GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc. The structures were confirmed by matrix-assisted laser desorption ionization mass spectrometry and a comparison with authentic sugar chains by high-pressure liquid chromatography. Various properties of BRA-2 were examined before and after deglycosylation. The susceptibility of BRA-2 to protease digestion was increased by deglycosylation. However, the inhibitory activity toward calcium carbonate crystallization as well as the hemagglutinating activity of deglycosylated BRA-2 was significantly decreased. These results suggest that the sugar chains of BRA-2 are important to both its structural stability and its function.     

栉孔扇贝钙调素类似蛋白基因的克隆及其与钙调素基因表达特征的比较分析

软体动物碳酸钙贝壳的形成过程涉及到C a2＋的吸收、转运、贮藏、分泌和沉积等,与钙代谢这一高度受控的复杂生理过程紧密相关。本研究以栉孔扇贝转录组测序结果为基础,通过RACE技术,从栉孔扇贝外套膜中克隆得到钙调素类似蛋白的cDNA序列,全长863 bp ,编码149个氨基酸,相应蛋白质的预测分子量约为17．0 ku ,理论等电点为4．03。钙调素类似蛋白具有4个可能的EF‐hand Ca2＋结合结构域,属于 EF‐hand钙结合蛋白家族,其氨基酸序列与栉孔扇贝钙调素钙调素的相似度为66％。半定量RT‐PCR检测显示,钙调素类似蛋白基因在外套膜中特异性高表达,预示其可能参与贝壳的矿化过程。实时定量PCR检测显示,钙调素类似蛋白基因的表达水平随环境中Ca2＋浓度的升高呈先升后降趋势,表明钙调素类似蛋白与外套膜中的钙代谢过程密切相关;在贝壳缺刻损伤后的再生过程中,钙调素类似蛋白基因表达量显著上升,暗示其积极参与到了贝壳的再生过程中。上述结果为进一步阐明钙调素类似蛋白基因的功能及其在栉孔扇贝生物矿化过程中的作用提供可能的理论依据。     

几种木材中硅石的研究

要实现木材-无机质复合材的人工模拟,其关键还是在于研究和探讨木材生物矿化的机理,因此要对木材中无机物的情况进行研究,从而获取生物矿化所形成的木材/无机质复合材料的形成机理,以此来指导木材的生物改性或木材/无机复合材的仿生合成。本文采用光学显微镜对几种木材/二氧化硅生物矿化复合材中硅石的分布进行观察发现:硅石主要分布在木射线细胞中,大量的晶体在木射线细胞以及轴向薄壁细胞中均有分布;采用重量法对几种木材/二氧化硅生物矿化复合材中二氧化硅含量情况进行测定表明:子京、山油柑、柚木、柠檬桉、山竹子等5种木材/二氧化硅生物矿化复合材中二氧化硅含量分别为1.5106%、0.8941%、0.8654%、0.2155%、0.1676%。     

Understanding Nanocalcification: A Role Suggested for Crystal Ghosts

The present survey deals with the initial stage of the calcification process in bone and other hard tissues, with special reference to the organic-inorganic relationship and the transformation that the early inorganic particles undergo as the process moves towards completion. Electron microscope studies clearly exclude the possibility that these particles might be crystalline structures, as often believed, by showing that they are, instead, organic-inorganic hybrids, each comprising a filamentous organic component (the crystal ghost) made up of acidic proteins. The hypothesis is suggested that the crystal ghosts bind and stabilize amorphous calcium phosphate and that their subsequent degradation allows the calcium phosphate, once released, to acquire a hydroxyapatite, crystal-like organization. A conclusive view of the mechanism of biological calcification cannot yet be proposed; even so, however, the role of crystal ghosts as a template of the structures usually called “crystallites” is a concept that has gathered increasing support and can no longer be disregarded.     

Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed.     

木材细胞中二氧化硅的吸收、运输与聚积

硅石在很多木材细胞中都可见(如紫果冷杉、樟科等),它与木材本身构成了一种复合材料即木材/无机质复合材,使木材的物理力学性能得以改善,克服了木材自身的一些缺陷(如易腐、易燃、尺寸不稳定性、各向异性等).作者根据前人对木材细胞中二氧化硅(SiO2)的分布、形态和含量的初步分析,归纳总结木材细胞中二氧化硅(SiO2)的形成过程及其影响因素即木材细胞中SiO2的吸收、运输及聚积,影响木材细胞中SiO2的吸收、运输及聚积的因素,为进一步研究木材细胞中硅生物矿化的形成过程做准备.     

以水稻叶片细胞壁为模板矿化合成纳米SiO2

人工培养条件下施用正硅酸乙酯(TEOS),通过化学调控在水稻叶片外表皮细胞间隙以细胞壁为模板生物矿化合成纳米尺寸有序SiO2材料.结果表明:SiO2材料有序结构体为条形片状,每条长150～200 nm,宽约50 nm.各纳米SiO2结构体互相堆积规整取向,结构体间有1～5nm的“重叠区”,构成相隔50 ～ 70 nm的周期性有序空间结构.能谱分析显示矿化纳米SiO2材料主要含有Si、O和C元素.     

Biomimetic Acid Soil Amelioration using Indigenous Soil Isolates in Comparison to other Potential Microorganism

In the present study, four different soil isolates were screened and evaluated for their acid neutralization capacity in liquid culture and soil column tests with either artificial soil or real acid soil. Miniaturized artificial soil column tests using Aspergillus fumigatus, Aureobasidium pullulans, and Myxococcus xanthus were also included. In the liquid-phase experiment, two isolates (designated ‘A’ and ‘B’) effectively increased the medium pH from 4 to 6.74 and 6.53, respectively, during the 6 d, and the ammonium-nitrogen (NH₄⁺-N) concentration increased from 400 ppm to 1000 ppm (isolate A). The isolates A and B were identified as Enterococcus hirae and Clostridium sp. in 16S ribosomal ribonucleic acid (rRNA) analysis. Artificial soil pH increased more quickly with soil isolates than in comparison to A. fumigatus or A. pullulans. In real acid soil pH increased from 4.2 to about pH 6.5 within 4 d. This suggests that biomimetic approaches could be valuable for acid soil amelioration.     

Expression profiles of nine biomineralization genes and their relationship with pearl nacre thickness in the pearl oyster,Pinctada fucata martensii Dunker

Pinctada fucata martensii is an ideal animal for study of biomineralization. Although dozens of genes have been identified, the molecular mechanism of biomineralization remains still unclear. The purpose here was to discover the expression profiles of nine biomineralization genes in related tissues: mantle edge (ME), mantle centre (MC) and pearl sac (PS), and to explore the relationships between expression level and nacre thickness. The expression levels of seven genes (ACCBP, aspein, CaM, EFCBP, KRMP, nacrein and prismalin‐14) showed no significant difference between ME and MC, but were significantly higher than those in PS. The expression level of N19 was the same in ME and PS, significantly higher than that in MC. However, msi60 in ME, MC and PS showed no significant differences in expression level. In addition, the correlations of expression levels between ME, MC and PS were highly significant, indicating that there are some similar function and mechanism among the three tissues. Also the nine genes had significant correlation of expression levels between one another. Furthermore, no other genes from oysters which produced pearls of different grades showed significant difference in the expression level, except CaM in MC, which had significantly higher expression level in the medium pearl grade than in the plain nucleus grade. Moreover, the expression level of msi60 in MC of host oyster was significantly correlated with produced pearl layer thickness, suggesting that msi60 might play an important role in pearl formation and host oyster may also participate in the development of pearl.