转昆虫抗冻蛋白基因增强甘薯抗冻能力

为明确昆虫抗冻蛋白基因转入甘薯(Ipomoea batatas)后是否能提升其抗冻能力,进而为培育甘薯抗冻育种材料奠定基础,将黄粉虫(Tenebrio molitor)抗冻蛋白基因TmAFP导入植物基因表达质粒,经农杆菌介导的遗传转化获得抗冻甘薯新材料。以甘薯品种Huachano为受体材料建立甘薯植株高效再生体系,并采用不同成分的体细胞胚成熟培养基培养胚性悬浮细胞。胚性愈伤组织对除草剂的敏感性测试结果表明,转基因阳性植株筛选的最适培养基为MS+0.2 mg·L–12,4-D+0.8 mg·L^–1 GAP+100 mg·L^–1 Carb。将表达质粒分别转化Huachano后共获得7个胚性愈伤团并最终获得42株再生抗性植株,其中转pSUIBEV3-AFP有23个株系,转pCAMBIA-AFP有19个株系,经PCR、Southern杂交和RT-PCR检测后证实TmAFP基因已整合至甘薯基因组中并获得表达。将转基因甘薯及对照植株在–1℃下处理15小时后转移至室温,结果表明,转基因甘薯植株的抗冻能力显著提升。     

Efficient Organic Solar Cell with 16.88% Efficiency Enabled by Refined Acceptor Crystallization and Morphology with Improved Charge Transfer and Transport Properties

Single‐layered organic solar cells (OSCs) using nonfullerene acceptors have reached 16% efficiency. Such a breakthrough has inspired new sparks for the development of the next generation of OSC materials. In addition to the optimization of electronic structure, it is important to investigate the essential solid‐state structure that guides the high efficiency of bulk heterojunction blends, which provides insight in understanding how to pair an efficient donor–acceptor mixture and refine film morphology. In this study, a thorough analysis is executed to reveal morphology details, and the results demonstrate that Y6 can form a unique 2D packing with a polymer‐like conjugated backbone oriented normal to the substrate, controlled by the processing solvent and thermal annealing conditions. Such morphology provides improved carrier transport and ultrafast hole and electron transfer, leading to improved device performance, and the best optimized device shows a power conversion efficiency of 16.88% (16.4% certified). This work reveals the importance of film morphology and the mechanism by which it affects device performance. A full set of analytical methods and processing conditions are executed to achieve high efficiency solar cells from materials design to device optimization, which will be useful in future OSC technology development.     

New 2(3-->20)abeotaxane and 3,11-cyclotaxane from needles of Taxus cuspidata

Two new taxoid metabolites, 2alpha,7beta,10beta-triacetoxy-5alpha,13alpha-dihydroxy-2(3-->20)abeotaxa-4(20),11-dien-9-one (1) and 2alpha-acetoxy-5alpha-cinnamoyloxy-9alpha,10beta-dihydroxy-3,11-cyclotax-4(20)-en-13-one (2), were isolated from the methanol extract of needles of the Japanese yew, Taxus cuspidata.     

Abnormal B-cell responses to chemokines, disturbed plasma cell localization, and distorted immune tissue architecture in Rgs1-/- mice

Normal lymphoid tissue development and function depend upon chemokine-directed cell migration. Since chemokines signal through heterotrimeric G-protein-coupled receptors, RGS proteins, which act as GTPase-activating proteins for Galpha subunits, likely fine tune the cellular responses to chemokines. Here we show that Rgs1(-/-) mice possess B cells that respond excessively and desensitize improperly to the chemokines CXCL12 and CXCL13. Many of the B-cell follicles in the spleens of Rgs1(-/-) mice have germinal centers even in the absence of immune stimulation. Furthermore, immunization of these mice leads to exaggerated germinal center formation; partial disruption of the normal architecture of the spleen and Peyer's patches; and abnormal trafficking of immunoglobulin-secreting cells. These results reveal the importance of a regulatory mechanism that limits and desensitizes chemokine receptor signaling.     

Silencing of subfamily I of protein phosphatase 2A catalytic subunits results in activation of plant defense responses and localized cell death

The central importance of protein phosphorylation in plant defense responses has been demonstrated by the isolation of several disease-resistance genes that encode protein kinases. In addition, there are many reports of changes in protein phosphorylation accompanying plant responses to pathogens. In contrast, little is known about the role of protein dephosphorylation in regulating plant defenses. We report that expression of the LePP2Ac1 gene, which encodes a catalytic subunit of the heterotrimeric protein phosphatase 2A (PP2Ac), is rapidly induced in resistant tomato leaves upon inoculation with an avirulent strain of Pseudomonas syringae pv. tomato. By analysis of PP2Ac gene sequences from several plant species, we found that PP2Ac genes cluster into two subfamilies, with LePP2Ac1 belonging to subfamily I. Virus-induced gene silencing (VIGS) in Nicotiana benthamiana was used to suppress expression of genes from subfamily I and not from subfamily II. The PP2Ac-silenced plants had greatly decreased PP2A activity, constitutively expressed pathogenesis-related (PR) genes, and developed localized cell death in stems and leaves. In addition, the plants were more resistant to a virulent strain of P. syringae pv. tabaci and showed an accelerated hypersensitive response (HR) to effector proteins from both P. syringae and the fungal pathogen, Cladosporium fulvum. Thus, catalytic subunits of PP2Ac subfamily I act as negative regulators of plant defense responses likely by de-sensitizing protein phosphorylation cascades.     

Assembly of the mammalian muscle acetylcholine receptor in transfected COS cells

We have investigated the mechanisms of assembly and transport to the cell surface of the mouse muscle nicotinic acetylcholine receptor (AChR) in transiently transfected COS cells. In cells transfected with all four subunit cDNAs, AChR was expressed on the surface with properties resembling those seen in mouse muscle cells (Gu, Y., A. F. Franco, Jr., P.D. Gardner, J. B. Lansman, J. R. Forsayeth, and Z. W. Hall. 1990. Neuron. 5:147-157). When incomplete combinations of AChR subunits were expressed, surface binding of 125I-alpha-bungarotoxin was not detected except in the case of alpha beta gamma which expressed less than 15% of that seen with all four subunits. Immunoprecipitation and sucrose gradient sedimentation experiments showed that in cells expressing pairs of subunits, alpha delta and alpha gamma heterodimers were formed, but alpha beta was not. When three subunits were expressed, alpha delta beta and alpha gamma beta complexes were formed. Variation of the ratios of the four subunit cDNAs used in the transfection mixture showed that surface AChR expression was decreased by high concentrations of delta or gamma cDNAs in a mutually competitive manner. High expression of delta or gamma subunits also each inhibited formation of a heterodimer with alpha and the other subunit. These results are consistent with a defined pathway for AChR assembly in which alpha delta and alpha gamma heterodimers are formed first, followed by association with the beta subunit and with each other to form the complete AChR.     

Comprehensive profiling of accessible surface glycans of mammalian sperm using a lectin microarray

It is well known that cell surface glycans or glycocalyx play important roles in sperm motility, maturation and fertilization. A comprehensive profile of the sperm surface glycans will greatly facilitate both basic research (sperm glycobiology) and clinical studies, such as diagnostics of infertility. As a group of natural glycan binders, lectin is an ideal tool for cell surface glycan profiling. However, because of the lack of effective technology, only a few lectins have been tested for lectin-sperm binding profiles. To address this challenge, we have developed a procedure for high-throughput probing of mammalian sperm with 91 lectins on lectin microarrays. Normal sperm from human, boar, bull, goat and rabbit were collected and analyzed on the lectin microarrays. Positive bindings of a set of ~50 lectins were observed for all the sperm of 5 species, which indicated a wide range of glycans are on the surface of mammalian sperm. Species specific lectin bindings were also observed. Clustering analysis revealed that the distances of the five species according to the lectin binding profiles are consistent with that of the genome sequence based phylogenetic tree except for rabbit. The procedure that we established in this study could be generally applicable for sperm from other species or defect sperm from the same species. We believe the lectin binding profiles of the mammalian sperm that we established in this study are valuable for both basic research and clinical studies.     

Immunoglobulin G Expression in Lung Cancer and Its Effects on Metastasis

Lung cancer is one of the leading malignancies worldwide, but the regulatory mechanism of its growth and metastasis is still poorly understood. We investigated the possible expression of immunoglobulin G (IgG) genes in squamous cell carcinomas and adenocarcinomas of the lung and related cancer cell lines. Abundant mRNA of IgG and essential enzymes for IgG synthesis, recombination activation genes 1, 2 (RAG1, 2) and activation-induced cytidine deaminase (AID) were detected in the cancer cells but not in adjacent normal lung tissue or normal lung epithelial cell line. The extents of IgG expression in 86 lung cancers were found to associate with clinical stage, pathological grade and lymph node metastasis. We found that knockdown of IgG with siRNA resulted in decreases of cellular proliferation, migration and attachment for cultured lung cancer cells. Metastasis-associated gene 1 (MTA1) appeared to be co-expressed with IgG in lung cancer cells. Statistical analysis showed that the rate of IgG expression was significantly correlated to that of MTA1 and to lymph node metastases. Inhibition of MTA1 gene expression with siRNA also led to decreases of cellular migration and attachment for cultured lung cancer cells. These evidences suggested that inhibition of cancer migration and attachment induced by IgG down-regulation might be achieved through MTA1 regulatory pathway. Our findings suggest that lung cancer-produced IgG is likely to play an important role in cancer growth and metastasis with significant clinical implications.     

Quantitative analysis of exogenous IGF-1 administration of intervertebral disc through intradiscal injection

Exogenous administration of IGF-1 has been proposed as a therapy for disc degeneration. The objectives of this study were to develop a numerical model for quantitatively analysing exogenous administration of IGF-1 into the intervertebral disc (IVD) via intradiscal injection and to investigate the effects of IGF-1 administration on distribution of glucose and oxygen in the IVD. In this study, the reversible binding reaction between IGF-1 and IGF binding proteins was incorporated into the mechano-electrochemical mixture model. The model was used to numerically analyse transport of IGF-1, glucose, oxygen and lactate in the IVD after IGF-1 administration. The enhancement of IGF-1 on lactate production was also taken into account in the theoretical model. The numerical analyses using finite element method demonstrated that the binding reactions significantly affect the time-dependent distribution of IGF-1 in the IVD. It was found that the region affected by IGF-1 was smaller and the duration of the therapeutic IGF-1 level was longer in the degenerated disc with a higher concentration of IGF binding proteins. It was also found that the IGF-1 injection can reduce glucose concentration and increase lactate accumulation (i.e., lower pH) in the IVD and these influences were regulated by the IGF-1 binding reactions. This study indicated the complexity of intradiscal administration of growth factors, which needs to be fully analysed in order to achieve a successful outcome. The new theoretical model developed in this study can serve as a powerful tool in analysing and designing the optimal treatments of growth factors for disc degeneration.