Characterization of a novel glycine-rich protein from the cell wall of maize silk tissues

The isolation, characterization and regulation of expression of a maize silk-specific gene is described. zmgrp5 (Zea mays glycine-rich protein 5) encodes a 187 amino acid glycine-rich protein that displays developmentally regulated silk-specific expression. Northern, Western, in situ mRNA hybridization and transient gene expression analyses indicate that zmgrp5 is expressed in silk hair and in cells of the vascular bundle and pollen tube transmitting tissue elements. The protein is secreted into the extracellular matrix and is localized in the cell wall fraction mainly through interactions mediated by covalent disulphide bridges. Taken together, these results suggest that the protein may play a role in maintaining silk structure during development. This is the first documented isolation of a stigma-specific gene from maize, an important agronomic member of the Poaceae family.Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accessions nos. AY095207, AY095208 and AAM16282.1).     

Shotgun proteomic analysis of the Bombyx mori anterior silk gland: An insight into the biosynthetic fiber spinning process

The Bombyx mori anterior silk gland (ASG) is a natural fiber manipulator for the material provided by the middle and posterior silk glands. In view of the significant role of the ASG in the liquid–crystal spinning process, a shotgun proteomics approach was taken to study the relationship between the function of proteins in the silkworm ASG and the spinning mechanism. A total of 1132 proteins with 7647 unique peptides were identified in the ASG dataset including some involved in the cuticle, ion transportation, energy metabolism, and apoptosis. Two putative cuticle‐specific proteins were highly and specifically expressed in the ASG; therefore, the ASG dataset could provide clues for comprehensive understanding of the natural silk spinning mechanism in the silkworm. All MS data have been deposited in the ProteomeXchange with identifier PXD000090.     

蚕丝纳米纤维在组织工程领域的研究进展

在组织工程中最为关键的是提供理想的生物材料支架,而结构和功能仿生是组织工程支架最重要的性能要求,但仿生组织工程支架的设计与构建必须由纳米纤维来实现.本文介绍蚕丝纳米纤维的性能特点,并通过国内外文献证实了家蚕丝素具有良好的生物相容性等优良特性,在组织工程领域广泛应用.然而,与家蚕丝相比,野蚕丝更利于细胞的黏附、生长,因此我们推测利用我国特有的野蚕丝素进行静电纺丝制取纳米纤维,有望在生物医学领域获得新的进展.     

Freeze-gelled silk fibroin protein scaffolds for potential applications in soft tissue engineering

Recently tissue engineering has escalated much interest in biomedical and biotechnological applications. In this regard, exploration of new and suitable biomaterials is needed. Silk fibroin protein is used as one of the most preferable biomaterials for fabrication of scaffolds and several new techniques are being adopted to fabricate silk scaffolds with greater ease, efficiency and perfection. In this study, a freeze gelation technique is used for fabrication of silk fibroin protein 3D scaffolds, which is both time and energy efficient as compared to the conventional freeze drying technique. The fabricated silk fibroin freeze-gelled scaffolds are evaluated micro structurally for morphology with scanning electron microscopy which reveals relatively homogeneous pore structure and good interconnectivity. The pore sizes and porosity of these scaffolds ranges between 60-110 μm and 90-95%, respectively. Mechanical test shows that the compressive strength of the scaffolds is in the range of 20-40 kPa. The applicability to cell culture of the freeze gelled scaffolds has been examined with human keratinocytes HaCat cells which show the good cell viability and proliferation of cells after 5 days of culture suggesting the cytocompatibility. The freeze-gelled 3D scaffolds show comparable results with the conventionally prepared freeze dried 3D scaffolds. Thus, this technique may be used as an alternative method for 3D scaffolds preparation and may also be utilized for tissue engineering applications.     

不同钙-醇溶解体系丝素蛋白的制备及表征研究

采用 ４种中性盐溶液 Ｃａ（ＮＯ３）２４Ｈ２Ｏ 甲醇、Ｃａ（ＮＯ３）２４Ｈ２Ｏ 乙醇、ＣａＣｌ２ 甲醇 水和 ＣａＣｌ２ 乙醇 水（摩尔比分别为 １∶２、１∶２、１∶２∶８、１∶２∶８）处理蚕丝纤维,透析后经冷冻干燥制成固体,利用ＳＤＳ ＰＡＧＥ、电镜扫描和红外光谱对制得的固体进行表征。ＳＤＳ ＰＡＧＥ结果表明：Ｃａ（ＮＯ３）２４Ｈ２Ｏ 醇体系降解丝素蛋白较 ＣａＣｌ２ 醇 水体系降解程度高;电镜扫描的结果表明 Ｃａ（ＮＯ３）２４Ｈ２Ｏ 甲醇和 ＣａＣｌ２ 乙醇 水溶解体系处理的丝素蛋白溶解比较完全,Ｃａ（ＮＯ３）２４Ｈ２Ｏ 甲醇处理的丝素蛋白冻干后为颗粒状,而 ＣａＣｌ２ 乙醇 水处理的丝素蛋白冻干后为片状。红外光谱的结果表明：４种溶液处理后的丝素蛋白构象均介于 β折叠和无规则卷曲之间,从而为丝素蛋白在药物缓释载体领域的应用提供了一定的理论依据。     

Tent-based thermoregulation in social caterpillars of Eriogaster lanestris (Lepidoptera: Lasiocampidae): behavioral mechanisms and physical features of the tent

(1) We investigated thermoregulatory behavior of social tent building caterpillars of Eriogaster lanestris.

(2) The silk layers of the tent shield most of the incoming radiation and reduce heat exchange with the surroundings by convective heat loss.

(3) As a consequence its interior provides a wide range of temperatures.

(4) By changing their position inside or on the tent caterpillars are able to stabilize their body temperatures at 30–35°C over a wide range of ambient temperatures as long as solar irradiation is sufficiently strong.

(5) Overall behavioral thermoregulation takes precedence over the tent's physical features.     

利用生物工程技术生产蜘蛛丝的研究进展

蜘蛛丝是一种高分子蛋白纤维,具有高强度、高弹性等许多重要的优良特性,在军事、医学、工业、建筑、纺织等领域具有广泛而巨大的应用。然而蜘蛛的产丝量小,且无法高密度养殖以获取大量的蜘蛛丝,难以满足实际应用的需要。于是人们只能着眼于生物工程方法,即将蜘蛛丝蛋白基因转入其它生物体来表达生产蜘蛛丝蛋白,经过多年的研究,已取得很多重要的进展。对蜘蛛丝蛋白在微生物、植物、哺乳动物及家蚕等不同生物载体中表达的研究进展进行重点阐述,并探讨了已有研究的不足和今后研究展望,为进一步探索和研发蜘蛛丝的规模化生产方法提供借鉴与参考。     

蜘蛛基因组DNA Cosmid文库构建和拖丝蛋白基因的克隆

The genomic DNA Cosmid library was constructed from Nephila clavipes spider muscle using SuperCos 1 Cosmid as a vector.The title of library was >5×10 4 cfu/μg ligated DNA.On the basis of published sequence from a partial cDNA sequence of the 3′end of the dragline silk gene, we designed and synthesized 3 oligonucleotides.Oligonucleotides were labeled with non radioactive digoxigenin dUTP and detected with chemilluminescent substrate.56 positive recombinants were screen from the Cosmid library using DIG Oligo 2 as a probe.DNA dot hybridization using DIG Oligo 1 and DIG Oligo 3 as the probes, respectively, 3 positive signals were identified from 56 colonies.They were appeared the same pattern when DNA from the colones digested by restriction enzymes.The spider dragline silk gene was confirmed again by Southern blot hybridization.