食药用真菌多糖构效关系研究进展

真菌多糖具有抗病毒、抗凝血、抗肿瘤、免疫调节、降血脂、延缓衰老等多种生物活性,而多糖的功能与结构密切相关。多糖结构与功能关系的研究已经成为人们关注的一个热点。综述了食药用真菌多糖一级结构、高级结构及多糖的理化性质与其生物学活性之间的关系。     

卵巢肿瘤中P-糖蛋白、谷胱甘肽S转移酶-π的表达及临床意义

目的研究P-糖蛋白(P-gp)、谷胱甘肽S转移酶π(GST-π)在卵巢肿瘤中的表达及其临床意义。方法采用S-P免疫组化方法,检测57例卵巢恶性肿瘤、8例正常卵巢与4例良性肿瘤中P-gp、GST-π的表达。结果P-gp在卵巢恶性肿瘤与正常卵巢及良性肿瘤中的表达有显著性差异,P-gp表达与恶性肿瘤分期、分级无关,而与组织学类型及化疗有关。GST-π的表达在卵巢恶性肿瘤与正常卵巢及良性肿瘤中的表达有显著性差异,与化疗有关,而与组织学类型、分期、分级无关。结论卵巢恶性肿瘤中存在着原发耐药,P-gp及GST-π的表达与化疗耐药高度相关。     

鼻NK／T细胞淋巴瘤间质清道夫受体A的表达及意义

目的 观察清道夫受体A（scavenger receprorA,SR-A）在鼻NK／T细胞淋巴瘤间质中的表达,探讨其意义。方法 对鼻NK／T细胞淋巴瘤,鼻B细胞淋巴瘤以及鼻部炎症的石蜡标本进行HE染色和SP免疫组织化学染色检测SR-A的表达。结果 SR-A蛋白在鼻NK／T细胞淋巴瘤,鼻B细胞淋巴瘤和鼻部炎症中阳性率分别为92．7％,29．2％和6．25%。统计学分析发现,鼻NK／T细胞淋巴瘤中SR-A的表达与B细胞淋巴瘤和炎症中SR-A的表达均有显著差异（P〈0．001）。结论 SR-A可能在鼻NK／T细胞淋巴瘤的诊断及鉴别诊断中有一定的参考价值。     

BAK1 and BKK1 regulate brassinosteroid-dependent growth and brassinosteroid-independent cell-death pathways

Brassinosteroids (BRs) are phytosteroid hormones controlling various physiological processes critical for normal growth and development. BRs are perceived by a protein complex containing two transmembrane receptor kinases, BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) [1-3]. BRI1 null mutants exhibit a dwarfed stature with epinastic leaves, delayed senescence, reduced male fertility, and altered light responses. BAK1 null mutants, however, only show a subtle phenotype, suggesting that functionally redundant proteins might be present in the Arabidopsis genome. Here we report that BAK1-LIKE 1 (BKK1) functions redundantly with BAK1 in regulating BR signaling. Surprisingly, rather than the expected bri1-like phenotype, bak1 bkk1 double mutants exhibit a seedling-lethality phenotype due to constitutive defense-gene expression, callose deposition, reactive oxygen species (ROS) accumulation, and spontaneous cell death even under sterile growing conditions. Our detailed analyses demonstrate that BAK1 and BKK1 have dual physiological roles: positively regulating a BR-dependent plant growth pathway, and negatively regulating a BR-independent cell-death pathway. Both BR signaling and developmentally controlled cell death are critical to optimal plant growth and development, but the mechanisms regulating early events in these pathways are poorly understood. This study provides novel insights into the initiation and crosstalk of the two signaling cascades.     

Transgene flow to hybrid rice and its male-sterile lines

Gene flow from genetically modified (GM) crops to the same species or wild relatives is a major concern in risk assessment. Transgenic rice with insect and/or disease resistance, herbicide, salt and/or drought tolerance and improved quality has been successfully developed. However, data on rice gene flow from environmental risk assessment studies are currently insufficient for the large-scale commercialization of GM rice. We have provided data on the gene flow frequency at 17 distances between a GM japonica line containing the bar gene as a pollen donor and two indica hybrid rice varieties and four male-sterile (ms) lines. The GM line was planted in a 640m² in an isolated experimental plot (2.4 ha), which simulates actual conditions of rice production with pollen competition. Results showed that: (1) under parallel plantation at the 0-m zone, the transgene flow frequency to the ms lines ranged from 3.145 to 36.116% and was significantly higher than that to hybrid rice cultivars (0.037–0.045%). (2) Gene flow frequency decreased as the distance increased, with a sharp cutoff point at about 1–2 m; (3) The maximum distance of transgene flow was 30–40 m to rice cultivars and 40–150 m to ms lines. We believe that these data will be useful for the risk assessment and management of transgenic rice lines, especially in Asia where 90% of world's rice is produced and hybrid rice varieties are extensively used. Shirong Jia, Feng Wang and Lei Shi contributed equally to this investigation.     

Identification of three protein disulfide isomerase members from Haemaphysalis longicornis tick

Three genes encoding putative protein disulfide isomerase (PDI) were isolated from the Haemaphysalis longicornis EST database and designed as HlPDI-1, HlPDI-2, and HlPDI-3. All three PDI genes contain two typical PDI active sites CXXC and encode putative 435, 499, and 488 amino acids, respectively. The recombinant proteins expressed in Escherichia coli all show PDI activities, and the activities were inhibited by a PDI-specific inhibitor, zinc bacitracin. Western blot analysis and real-time PCR revealed that three HlPDIs were present in all the developmental stages of the tick as well as in the midgut, salivary glands, ovary, hemolymph, and fatbody of adult female ticks, but the three genes were expressed at the highest level in the egg stage. HlPDI-1 is expressed primarily in the ovary and secondarily in the salivary glands. HlPDI-2 and HlPDI-3 are expressed primarily in the salivary gland, suggesting that the PDI genes are important for tick biology, especially for egg development, and that they play distinct roles in different tissues. Blood feeding induced significantly increased expression of HlPDI-1 and HlPDI-3 in both partially fed nymphs and adults. Babesia gibsoni-infected larval ticks expressed HlPDI-1 and HlPDI-3 2.0 and 4.0 times higher than uninfected normal larval ticks, respectively. The results indicate that HlPDI-1 and HlPDI-3 might be involved in tick blood feeding and Babesia parasite infection in ticks.     

AtNHX8, a member of the monovalent cation: proton antiporter-1 family in Arabidopsis thaliana, encodes a putative Li/H antiporter

The Arabidopsis monovalent cation:proton antiporter-1 (CPA1) family includes eight members, AtNHX1-8. AtNHX1 and AtNHX7/SOS1 have been well characterized as tonoplast and plasma membrane Na+/H+ antiporters, respectively. The proteins AtNHX2-6 have been phylogenetically linked to AtNHX1, while AtNHX8 appears to be related to AtNHX7/SOS1. Here we report functional characterization of AtNHX8. AtNHX8 T-DNA insertion mutants are hypersensitive to lithium ions (Li+) relative to wild-type plants, but not to the other metal ions such as sodium (Na+), potassium (K+) and caesium (Cs+). AtNHX8 overexpression in a triple-deletion yeast mutant AXT3 that exhibits defective Na+/Li+ transport specifically suppresses sensitivity to Li+, but does not affect Na+ sensitivity. Likewise, AtNHX8 overexpression complemented sensitivity to Li+, but not Na+, in sos1-1 mutant seedlings, and increased Li+ tolerance of both the sos1-1 mutant and wild-type seedlings. Results of Li+ and K+ measurement of loss-of-function and gain-of-function mutants indicate that AtNHX8 may be responsible for Li+ extrusion, and may be able to maintain K+ acquisition and intracellular ion homeostasis. Subcellular localization of the AtNHX8-enhanced green fluorescent protein (EGFP) fusion protein suggested that AtNHX8 protein is targeted to the plasma membrane. Taken together, our findings suggest that AtNHX8 encodes a putative plasma membrane Li+/H+ antiporter that functions in Li detoxification and ion homeostasis in Arabidopsis.     

Effects of herbivore stress by Aphis medicaginis Koch on the Malondialdehyde contents and the activities of protective enzymes in different alfalfa varieties

The study focused on the dynamics of Malondialdehyde (MDA) contents and the activities of protective enzymes in the leaves of alfalfa varieties with various resistances to Aphis medicaginis Koch. The results showed that susceptible varieties always had higher MDA contents than resistant varieties, and the MDA contents tended to rise in both susceptible and resistant varieties in period of the varieties were pierced and sucked by aphids. Superoxide dismutase (SOD), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities in susceptible varieties were lower than those in resistant varieties, and in both susceptible and resistant varieties the SOD and POD activities tended to rise at first and then decline, and the PAL activities rose to their peaks and then tended to remain stable. In the susceptible and resistant varieties the catalase (CAT) activities appeared to rise and decline alternatively; the PPO activities in resistant varieties were lower than those in susceptible varieties in early growth, but higher than those in susceptible varieties in later growth. It follows that infested by aphids, susceptible and resistant varieties had the MDA contents, variations of SOD, POD, PAL and PPO activities were closely correlated with their aphid resistances, hence these indexes could be used as physiological indexes for testing aphid resistance of alfalfa, whereas the relations of their CAT activities to their resistances needed to be further studied.     

Establishing a minimum dataset for soil quality assessment based on soil properties and land-use changes

To assess soil quality, a minimum dataset (MDS) of soil properties has to be proposed commonly through calculating the total load of each candidate soil parameter on all of the qualified principal components by use of principal component analysis (PCA) and Norm-value computation. Considering intensive land-use changes, the method introduced in this study on MDS establishment integrates the quantified contributions of land-use type and land-use duration on each soil parameter by using multivariate analysis and mean multiple comparison. In this way, a MDS maximally representing all candidates with minimal loss of the soil quality information contained by those non-MDS soil parameters is established. The MDS proposed can not only well integrate the quantified influence of land-use changes and land-use duration on soil parameters, but is also quite flexible and extendable with the potential to be extrapolated to assess soil quality in other regions. Based on two sets of soil database obtained separately in 1985 and 2004, two MDSs established are compared with each other. It is found that only quite a small change in MDS components occurs during a 20-year period. For a better assessment of soil quality, it seems necessary to examine on what kind of temporal scale and how much MDS will change for a site-specific area with intensive land-use changes.