Improvement of foreign gene expression in transgenic rice ( Oryza sativa L. ) by matrix attachment regions (MARs)

Matrix attachment regions or matrix associated regions (MARs) were special DNA sequences in chromatin of eukaryotic cells that tightly associated with the nuclear matrix or scaffold in vitro after a combination of nuclease digestion and extraction. They were also called scaffold attachment regions (SARs) .     

Fabrication of Silk Scaffold Containing Simvastatin-Loaded Silk Fibroin Nanoparticles for Regenerating Bone Defects

Background:In the present study, a tissue engineered SF scaffold containing simvastatin-loaded SFNPs were used to stimulate the regeneration of the defected bone.Methods:At first, the porous SF scaffold was prepared using freeze-drying. Then simvastatin-loaded SFNPs were made by dissolvation method and embedded in the SF scaffold. Afterwards, the scaffold and the NPs were characterized in terms of physicochemical properties and the ability to release the simvastatin small molecule.Results:The results exhibited that the SF scaffold had a porous structure suitable for releasing the small molecule and inducing the proliferation and attachment of osteoblast cells. SFNPs containing simvastatin had spherical morphology and were 174 ± 4 nm in size with -24.5 zeta potential. Simvastatin was also successfully encapsulated within the SFNPs with 68% encapsulation efficiency. Moreover, the small molecule revealed a sustained release profile from the NPs during 35 days. The results obtained from the in vitro cell-based studies indicated that simvastatin-loaded SFNPs embedded in the scaffold had acceptable capacity to promote the proliferation and ALP production of osteoblast cells while inducing osteogenic matrix precipitation. Conclusion:The SF scaffold containing simvastatin-loaded SFNPs could have a good potential to be used as a bone tissue-engineered construct.     

Highly porous three-dimensional poly(lactide-co-glycolide) (PLGA) microfibrous scaffold prepared by electrospinning method: A comparison study with other PLGA type scaffolds on its biological evaluation

In this study, a three-dimensional (3D) poly(lactide-co-glycolide) (PLGA) microfibrous scaffold with high porosity (ca. 90 % porosity) was developed for evaluating its performance in tissue engineering application. A dope solution of PLGA/polyethylene oxide (PEO) blend was electrospun into a methanol coagulation bath for fabricating highly porous 3D PLGA scaffold and a salt leaching method was used for making interconnected pores of 100?C200 ??m size inside the scaffold. The morphological structure, pore size and porosity of the microfibrous scaffold were determined, and compared with twodimensional (2D) mat-type and 3D sponge-type of PLGA scaffold. Also, swelling ratio, water uptake and compressive strength were compared in order to elucidate the structure-property relationships of different types of the scaffolds, especially in a wet condition. As a result of scanning electron microscopy (SEM) observation, normal human dermal fibroblasts (nHDF) were migrated, attached, and proliferated well inside the 3D scaffold. MTT assay confirmed that the highly porous 3D PLGA microfibrous scaffold had superior cell adhesion and proliferation abilities due to fibrous structure of large specific surface area, and interconnected pore structure. Therefore, this high performance 3D PLGA scaffold can have a high potentiality for application in tissue engineering in comparison with conventional PLGA scaffolds.     

Functionalizing cellulose scaffold prepared by ionic liquid with bovine serum albumin for biomedical application

The present study reports the preparation of a cellulose scaffold for tissue engineering directly from cellulose fiber using ionic liquid (IL) by the NaCl leaching method with bovine serum albumin (BSA), which is well known protein utilized for biomedical applications like degradation of polymer, cell attachment and proliferation on scaffold. The 1-n-allyl-3-methylimidazolium chloride (AmimCl) IL was used as a solvent for cellulose. The morphology of the scaffold was studied by scanning electron microscopy (SEM) and the images showed that the pore sizes of the scaffolds were about 200 µm. In addition, the water uptake (WU) and degree of degradation of the cellulose scaffold were measured. Meanwhile, the biocompatibility and bioactivity of the scaffold were determined via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide (MTT) assay and the Live/Dead viability test. The various results demonstrated the ability of the Mesenchymal stem cells (MSC) to attach to the surface of the scaffolds amplified as percentage of BSA increased in cellulose scaffold.     

Functionalized multi-walled carbon nanotubes with hyperbranched aromatic polyamide for poly(methyl methacrylate) composites

Multi-walled carbon nanotubes (MWCNTs) were functionalized with hyperbranched aromatic polyamide (HAP) by in situ polymerization and by the AB ₂ approach to enhance the mechanical properties of poly(methylmethacrylate) (PMMA) composites. Various concentrations of HAP-functionalized MWCNTs (HAP-f-MWCNTs) were used to prepare HAP-f-MWCNT-reinforced PMMA composite films. The covalent attachment of HAP to the MWCNTs, as achieved by in situ functionalization, resulted in effective dispersion of the MWCNTs in the PMMA matrix, thus enhancing the mechanical and thermal properties of the composite films. The breaking stress of the composites increased largely with the HAP-f-MWCNT loading.     

芥菜型油菜A09染色体BAC重叠群的构建及分析

利用定位在芥菜型油菜A09染色体上的分子标记对芥菜型油菜（Brassica juncea）ZBjuH BAC文库进行PCR步移筛选。共筛选出725个BAC,测定了315个BAC的末端序列,获得564条BAC末端序列,BLAST分析表明这些末端序列对应白菜（Brassica rapa）基因组序列支架45、支架81、支架40,支架134、支架145和支架59的同源区域,构建了芥菜型油菜A09染色体大约6.3 Mb的BAC重叠群,为芥菜型油菜A09染色体物理图谱构建奠定了基础。     

Chondrogenic differentiation of rat mesenchymal stem cells on silk fibroin/chondroitin sulfate/hyaluronic acid ternary scaffolds

Cartilage repair is a challenge in bone tissue reconstruction. In this study, silk fibroin (SF), chondroitin sulfate (CS) and hyaluronic acid (HA) were employed to fabricate scaffolds for tissue engineered cartilage by freeze drying technique. The secondary pores were formed in the main pores of SF/CS/HA scaffold which improved the pore connectivity and equilibrium swelling of the scaffold. Furthermore, rat bone marrow mesenchymal stem cells were seeded on the scaffolds to evaluate the cell adhesion and proliferation. Results of hematoxylin/eosin staining and cell counting kit-8 assay showed that the cells migration and differentiation of SF/CS/HA (80/15/5) scaffold were better than that of SF/CS/HA scaffolds with different ratios after 7 days culture. Moreover, immunohistochemistry and scanning electron microscope demonstrated that large amounts of collagen II and proteoglycans of the cells were expressed in the SF/CS/HA 3D scaffold, while the expression of collagen I was barely visible by immunohistochemistry. Abound of extracellular matrix was formed to morphologically round and distributed uniformly throughout the scaffolds. The 3D ternary scaffold could promote the cells chondrogenic differentiation without using any inductive agent and offer potential for cartilage tissue regeneration.     

Growth of primary hippocampal neurons on multichannel silk fibroin scaffold

Particular attention has been given to axonal outgrowth of neurons to understand how topographical surface cues influence attachment and subsequent directional migration and growth. In present study, the silk fibroin (SF) scaffold with uniaxial channels was prepared by directional freeze-drying processes. The average pore diameter, the porosity, and pore density of the scaffold are 120 µm, 88 %, and 203 mm^?2, respectively. Further, hippocampal neurons were seeded onto the scaffold and the hippocampal neurons morphology was investigated. Cell-cell networks and cell-matrix interactions had been established by newly formed axons and the diversity of neurons was much higher after culturing 7 days. The neurons expressed β-III-tubulin and nerve filament, while glial fibrillary acidic protein immunofluorescence was barely above background. These results indicated that the SF scaffolds with uniaxial multichannels could be guided axons of neurons spread along the channels. SF scaffolds with oriented pores have a potential for nerve tissue regeneration.     

Preparation, structure, and in vitro degradation behavior of the electrospun poly(lactide-co-glycolide) ultrafine fibrous vascular scaffold

The PLGA ultrafine fibrous scaffold was successfully fabricated by electrospinning. The morphology and properties of the PLGA vascular scaffolds were examined. In particular, the in vitro degradation behavior of the electrospun PLGA vascular scaffolds was investigated by means of morphology, microstructure, mass loss, M_w, and breaking strength characterization. The results showed that electrospun scaffold possessed ultrafine fibrous and porous structure, and had adequate mechanical properties to be developed as a substitute for native blood vessels. In vitro degradation study showed that the PLGA ultrafine fibrous scaffold could biodegrade in the PBS solution, and the mass loss, M_w, and breaking strength studies indicated that degradation rate of the electrospun PLGA nanofibers was greater in the first 2 weeks. After the degradation of 2 weeks, the degradation slowed down. Furthermore, with the extension of the degradation time, the thermal decomposition temperature of the PLGA scaffold decreased gradually. The results indicated that the electrospun PLGA vascular scaffold could be considered as an ideal candidate for tissue-engineered blood vessel.     

The Role of Biodegradable Engineered Nanofiber Scaffolds Seeded with Hair Follicle Stem Cells for Tissue Engineering

Background

The aim of this study was to fabricate the poly caprolactone (PCL) aligned nanofiber scaffold and to evaluate the survival, adhesion, proliferation, and differentiation of rat hair follicle stem cells (HFSC) in the graft material using electrospun PCL nanofiber scaffold for tissue engineering applications.

Methods

The bulge region of rat whisker was isolated and cultured in DMEM: nutrient mixture F-12 supplemented with epidermal growth factor. The morphological and biological features of cultured bulge cells were observed by light microscopy using immunocytochemistry methods. Electrospinning was used for production of PCL nanofiber scaffolds. Scanning electron microscopy (SEM), 3-(4, 5-di-methylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, and histology analysis were used to investigate the cell morphology, viability, attachment and infiltration of the HFSC on the PCL nanofiber scaffolds.

Results

The results of the MTT assay showed cell viability and cell proliferation of the HFSC on PCL nanofiber scaffolds. SEM microscopy images indicated that HFSC are attached, proliferated and spread on PCL nanofiber scaffolds. Also, immunocytochemical analysis showed cell infiltration and cell differentiation on the scaffolds.

Conclusion

The results of this study reveal that PCL nanofiber scaffolds are suitable for cell culture, proliferation, differentiation and attachment. Furthermore, HFSC are attached and proliferated on PCL nanofiber scaffolds.Key Words: Nanofiber, Electrospinning, Stem cells, Tissue engineering     

Fabrication of Gelatin-Based Electrospun Composite Fibers for Anti-Bacterial Properties and Protein Adsorption

A major goal of biomimetics is the development of chemical compositions and structures that simulate the extracellular matrix. In this study, gelatin-based electrospun composite fibrous membranes were prepared by electrospinning to generate bone scaffold materials. The gelatin-based multicomponent composite fibers were fabricated using co-electrospinning, and the composite fibers of chitosan (CS), gelatin (Gel), hydroxyapatite (HA), and graphene oxide (GO) were successfully fabricated for multi-function characteristics of biomimetic scaffolds. The effect of component concentration on composite fiber morphology, antibacterial properties, and protein adsorption were investigated. Composite fibers exhibited effective antibacterial activity against Staphylococcus aureus and Escherichia coli. The study observed that the composite fibers have higher adsorption capacities of bovine serum albumin (BSA) at pH 5.32–6.00 than at pH 3.90–4.50 or 7.35. The protein adsorption on the surface of the composite fiber increased as the initial BSA concentration increased. The surface of the composite reached adsorption equilibrium at 20 min. These results have specific applications for the development of bone scaffold materials, and broad implications in the field of tissue engineering.     

Measurement of genetic and environmental variation in barley (Hordeum vulgare) grain hardness

In this study, we assessed a broad range of barley breeding lines and commercial varieties by three hardness methods (two particle size methods and one crush resistance method (SKCS—Single-Kernel Characterization System), grown at multiple sites to see if there was variation in barley hardness and if that variation was genetic or environmentally controlled. We also developed near-infrared reflectance (NIR) calibrations for these three hardness methods to ascertain if NIR technology was suitable for rapid screening of breeding lines or specific populations. In addition, we used this data to identify genetic regions that may be associated with hardness. There were significant (p<0.05) genetic effects for the three hardness methods. There were also environmental effects, possibly linked to the effect of protein on hardness, i.e. increasing protein resulted in harder grain. Heritability values were calculated at >85% for all methods. The NIR calibrations, with R² values of >90%, had Standard Error of Prediction values of 0.90, 72 and 4.0, respectively, for the three hardness methods. These equations were used to predict hardness values of a mapping population which resulted in genetic markers being identified on all chromosomes but chromosomes 2H, 3H, 5H, 6H and 7H had markers with significant LOD scores. The two regions on 5H were on the distal end of both the long and short arms. The region that showed significant LOD score was on the long arm. However, the region on the short arm associated with the hardness (hordoindoline) genes did not have significant LOD scores. The results indicate that barley hardness is influenced by both genotype and environment and that the trait is heritable, which would allow breeders to develop very hard or soft varieties if required. In addition, NIR was shown to be a reliable tool for screening for hardness. While the data set used in this study has a relatively low variation in hardness, the tools developed could be applied to breeding populations that have large variation in barley grain hardness.     

Freezing behavior of potato (Solanum tuberosum) tubers in soil

Volunteer potatoes are a major weed problem in potato rotations in regions with mild winter soil temperatures. Freezing dynamics of potato tubers in air have been previously reported, but freezing dynamics of tubers in soil may differ due to ice nucleation sites and soil water associated with soil. Laboratory experiments conducted in hydrated and dry soil columns and field experiments were conducted to determine cold temperatures required to kill potato tubers in soil. Potato tubers in air-dried soil columns exposed to decreasing temperatures typically supercooled to ?3 to ?7 C before exhibiting a distinct exotherm, which stabilized at ?1.4 to ?1.5 C, representing the freezing point of tubers. Tubers that were supercooled and removed from the cold environment before experiencing this exotherm were able to sprout and had no visual symptoms of freezing injury, whereas tubers that experienced the exotherm were nonviable and unable to sprout. Tubers in soil columns hydrated to 7% SWC supercooled much less than tubers in dry soil and exhibited an exotherm that stabilized near ?1.9 C. Tubers exposed to temperatures near the tuber-freezing point (?1.4 to ?1.9 C) for periods of 1 min to 24 h, but not undergoing an exotherm, exhibited varying degrees of injury, which increased with time of exposure. Tubers held at ?1.0 C for 4 to 24 h were unharmed and able to sprout similar to controls. In field trials conducted from 1993 to 1999 in the Columbia Basin of Washington, tubers buried at shallow depths (5 cm) were much more likely to experience lethal cold temperatures than tubers buried deeper. In general, when minimum soil temperature at tuber depth reached ?1.5 to ?1.9 C or lower, some tuber mortality occurred and when soil temperature at tuber depth reached ?2.8 C or lower, extensive tuber death occurred. Monitoring of winter soil temperatures by depth in potato- growing regions could be used to predict severity of volunteer potato for the subsequent growing season.     

我国稻瘟病菌对水稻新品种(系)、新组合的致病性评价

为探明我国稻瘟病菌对近年来育成的部分水稻新品种(系)、新组合的致病力,用来自浙江、四川、湖北、广东、云南、吉林、北京等7个省(市)的92个稻瘟病菌菌株测定了39个水稻新品种(系)或新组合的抗性,分析了稻瘟病菌的致病力和品种的抗病性。结果表明,不同稻区稻瘟病菌菌株对籼、粳、杂交稻的致病力存在明显差异。筛选出一批毒力频率在20%以下,抗性较好的籼、粳稻新品种(系)和杂交稻新组合。同时用联合致病性系数和联合抗病性系数分析了病菌和品种的群体互作以及抗瘟新品种(系)、新组合的利用价值。     

Jellyfish Collagen: A Biocompatible Collagen Source for 3D Scaffold Fabrication and Enhanced Chondrogenicity

Osteoarthritis (OA) is a multifactorial disease leading to degeneration of articular cartilage, causing morbidity in approximately 8.5 million of the UK population. As the dense extracellular matrix of articular cartilage is primarily composed of collagen, cartilage repair strategies have exploited the biocompatibility and mechanical strength of bovine and porcine collagen to produce robust scaffolds for procedures such as matrix-induced chondrocyte implantation (MACI). However, mammalian sourced collagens pose safety risks such as bovine spongiform encephalopathy, transmissible spongiform encephalopathy and possible transmission of viral vectors. This study characterised a non-mammalian jellyfish (Rhizostoma pulmo) collagen as an alternative, safer source in scaffold production for clinical use. Jellyfish collagen demonstrated comparable scaffold structural properties and stability when compared to mammalian collagen. Jellyfish collagen also displayed comparable immunogenic responses (platelet and leukocyte activation/cell death) and cytokine release profile in comparison to mammalian collagen in vitro. Further histological analysis of jellyfish collagen revealed bovine chondroprogenitor cell invasion and proliferation in the scaffold structures, where the scaffold supported enhanced chondrogenesis in the presence of TGFβ1. This study highlights the potential of jellyfish collagen as a safe and biocompatible biomaterial for both OA repair and further regenerative medicine applications.     

花生种质资源抗花生锈病初步鉴定

本文总结了“六五”和“七五”期间,对4000多份花生种质资源抗锈性的鉴定结果。国内资源2508份,表现高抗和中抗的分别为21份和237份;国外资源1644份,表现高抗和中抗的分别为234和188份。不同类型的品种以及不同地区来源的花生品种,其抗性表现不同,即使是同一品种,在不同国家和地区,其抗性表现也不完全一致,本试验还从珍珠豆型花生品种中鉴定出抗锈资源,并首次对龙生型花生进行抗锈性鉴定。     

多倍体茶树的细胞学研究(一)

对从二倍体茶树品种凤凰水仙中获得的1株高度不孕的三倍体茶树的形态特征特性、核型和减数分裂的染色体行为进行观察表明:其核型组成为2n=3x=45=36M+9SM。可区分出3个基本相同的染色体组,同源染色体组3个成员的形态极为相似。终变期观察到1—9价体、多价体环或链等构型,所有细胞可见1—12个三价体,三价体在每个细胞中平均出现次数较高,为6.13次。后期Ⅰ∶86％的细胞具有1—6条落后染色体;到达每极区染色体数变化于12—29之间,82％的细胞具有18—24条染色体。后期Ⅱ∶93％的纺锤体中具有1—4条落     

水稻与稻瘟病菌的蛋白质—细胞在体外的相互作用初步研究

在离体条件下,用蛋白质双向电泳技术分析水稻与稻瘟病菌在接触反应开始阶段的蛋白质变化情况,以寻找参与寄主与病原菌相互作用的蛋白质分子,结果表明在两个蛋白质与孢子或菌丝体混合后从电泳胶上消失,同时了出现了另外两个蛋白质,还没确定两个消失的蛋白质是被菌体细胞所吸附,还是由于被修饰而导致电泳行为改变。上述蛋白质在抗病和感病水稻品种中都存在,是组成型的,推测它们可能参与寄主与病原菌的接触反应,另外还发现,当悬浮培养的水稻细胞与稻瘟病菌的菌丝体蛋白质接触后会产生一些新的蛋白质分子,但孢子蛋白无此作用。由此推测水稻与稻瘟病菌的特异识别反应可能发生在孢子萌发之后和菌丝体阶段,以上结果在亲和与非亲和体系中相同。文中对此现象提出了初步解释,还介绍了一个在离体条件下研究寄主与病原菌的蛋白质-细胞相互作用的简单方法。