Papaya Leaf Curl Guangdong Virus and Ageratum Yellow Vein Virus Associated with Leaf Curl Disease of Tobacco in China

Two samples (YC7, YC27) of Nicotiana tabacum showing leaf curling, vein swelling and enations on undersides of leaves were collected in the Fujian Province of China in 2007. Virus isolates YC7‐1 and YC7‐2 (associated with betasatellite, YC7‐2β) were detected in both samples. The complete DNA‐A sequence of YC7‐1 (FJ869907) comprised 2741 nucleotides (nt). The complete DNA‐A (FJ869908) and betasatellite (FJ869909) sequence of YC7‐2 consisted of 2754 and 1344 nt, respectively. YC7‐1 had the highest nucleotide sequence identity (97.3%) with Papaya leaf curl Guangdong virus (PaLCuGuV‐[CN:Gd2:02], AJ558122). YC7‐2 had the highest sequence identity (90.1%) with Ageratum yellow vein virus (AYVV‐TW[TW:Tai:99], AF307861) and its betasatellite (96.5%) with Ageratum yellow vein betasatellite (AYVB‐[TW:CHu:02], AJ542495). These indicate that YC7‐1 and YC7‐2 are isolates of PaLCuGuV and AYVV, respectively. Symptoms including leaf curling, vein swelling and enations on undersides of leaves were observed in N. tabacum and N. glutinosa when infected by whiteflies with sample YC7 as the viral source under greenhouse conditions. PCR results showed that these infected plants contained both YC7‐1 and YC7‐2/YC7‐2β. To our knowledge, this is the first report of PaLCuGuV and AYVV/AYVB co‐infecting N. tabacum in China.     

Analysis of genetic diversity and population structure of peanut cultivars and breeding lines from China,India and the US using simple sequence repeat markers

Cultivated peanut is grown worldwide as richsource of oil and protein. A broad genetic base is needed for cultivar improvement. The objectives of this study were to develop highly informative simple sequence repeat(SSR)markers and to assess the genetic diversity and population structure of peanut cultivars and breeding lines from different breeding programs in China, India and the US. A total of 111 SSR markers were selected for this study, resulting in a total of 472 alleles. The mean values of gene diversity and polymorphic information content(PIC) were 0.480 and 0.429, respectively.Country-wise analysis revealed that alleles per locus in three countries were similar. The mean gene diversity in the US,China and India was 0.363, 0.489 and 0.47 with an average PIC of 0.323, 0.43 and 0.412, respectively. Genetic analysis using the STRUCTURE divided these peanut lines into two populations(P_1, P_2), which was consistent with the dendrogram based on genetic distance(G_1, G_2) and the clustering of principal component analysis. The groupings were related to peanut market types and the geographic origin with a few admixtures. The results could be used by breeding programs to assess the genetic diversity of breeding materials to broaden the genetic base and for molecular genetics studies.     

Effect of peroxisome proliferators on the methylation and protein level of the c-myc protooncogene in B6C3F1 mice liver

Peroxisome proliferators in general are nongenotoxic mouse liver carcinogens for which DNA hypomethylation and altered gene expression are proposed mechanisms. Therefore, the peroxisome proliferators 2,4-dichlorophenoxyacetic acid (2,4-D), dibutyl phthalate (DBP), gemfibrozil, and Wy-14,643 were evaluated for the ability to alter the methylation and expression of the c-myc protooncogene. Male B6C3F1 mice were administered for 6 days in their diet Wy-14,643 (5-500 ppm), 2,4-D (1,680 ppm), DBP (20,000 ppm), or gemfibrozil (8,000 ppm). All four peroxisome proliferators caused hypomethylation of the c-myc gene in the liver. Wy-14,643 appeared to be the most efficacious with a threshold between 10 and 50 ppm. The level of the c-myc protein was increased by Wy-14,643, but not the other peroxisome proliferators. When female B6C3F1 mice received a two-thirds partially hepatectomy and 16 h later were administered 50 mg/kg Wy-14,643 by gavage, hypomethylation of the gene occurred 24 h later. Hypomethylation was not found in mice that received Wy-14,643 following a sham operation. Hypomethylation of the c-myc gene within 24 h of administering Wy-14,643 after a partial hepatectomy but not after a sham operation supports the hypothesis that the peroxisome proliferators prevent methylation of hemimethylated sites formed by DNA replication.     

Rice stripe tenuivirus p2 may recruit or manipulate nucleolar functions through an interaction with fibrillarin to promote virus systemic movement

Rice stripe virus (RSV) is the type species of the genus Tenuivirus and represents a major viral pathogen affecting rice production in East Asia. In this study, RSV p2 was fused to yellow fluorescent protein (p2‐YFP) and expressed in epidermal cells of Nicotiana benthamiana. p2‐YFP fluorescence was found to move to the nucleolus initially, but to leave the nucleolus for the cytoplasm forming numerous distinct bright spots there at later time points. A bimolecular fluorescence complementation (BiFC) assay showed that p2 interacted with fibrillarin and that the interaction occurred in the nucleus. Both the nucleolar localization and cytoplasmic distribution of p2‐YFP fluorescence were affected in fibrillarin‐silenced N. benthamiana. Fibrillarin depletion abolished the systemic movement of RSV, but not that of Tobacco mosaic virus (TMV) and Potato virus X (PVX). A Tobacco rattle virus (TRV)‐based virus‐induced gene silencing (VIGS) method was used to diminish RSV NS2 (encoding p2) or NS3 (encoding p3) during RSV infection. Silencing of NS3 alleviated symptom severity and reduced RSV accumulation, but had no obvious effects on virus movement and the timing of symptom development. However, silencing of NS2 abolished the systemic movement of RSV. The possibility that RSV p2 may recruit or manipulate nucleolar functions to promote virus systemic infection is discussed.     

Two Novel Bacteriophages of Thermophilic Bacteria Isolated from Deep-Sea Hydrothermal Fields

Bacteriophages of thermophiles are of great interest due to their important roles in many biogeochemical and ecological processes. However, no virion has been isolated from deep-sea thermophilic bacteria to date. In this investigation, two lytic bacteriophages (termed Bacillus virus W1 and Geobacillus virus E1) of thermophilic bacteria were purified from deep-sea hydrothermal fields in the Pacific for the first time. Bacillus virus W1 (BVW1) obtained from Bacillus sp. w13, had a long tail (300nm in length and 15 nm in width) and a hexagonal head (70 nm in diameter). Another virus, Geobacillus virus E1 (GVE1) from Geobacillus sp. E26323, was a typical Siphoviridae phage with a hexagonal head (130 nm in diameter) and a tail (180 nm in length and 30 nm in width). The two phages contained double-stranded genomic DNAs. The genomic DNA sizes of BVW1 and GVE1 were estimated to be about 18 and 41 kb, respectively. Based on SDS-PAGE of purified virions, six major proteins were revealed for each of the two phages. The findings in our study will be very helpful to realize the effect of virus on thermophiles as well as the communities in deep-sea hydrothermal fields.     

杏鲍菇抗烟草花叶病毒蛋白的筛选

采用离子交换层析和凝胶层析方法,从杏鲍菇干样中分离得到多个蛋白组分,经枯斑寄主检测,发现多个蛋白组分都有抗烟草花叶病毒(TMV)的活性,对TMV的抑制率均在70%以上,高者可达99%。其中xb68Ab已得到了纯化,分子量约为23.7kD,在心叶烟和苋色藜上它对TMV侵染的抑制率分别达到99.43%和98.9%。     

两株海洋真菌的鉴定及其次级代谢产物抑制烟草花叶病毒及抗肿瘤活性

摘要：【目的】通过对2株活性海洋真菌发酵产物提取物抑制烟草花叶病毒和抗肿瘤活性进行研究,为进一步得到活性纯品化合物作为抗病毒及抗肿瘤的先导化合物奠定基础。【方法】菌株发酵产物的粗提物是通过甲醇浸取并在真空条件下蒸干得到的。粗提物中溶于水的部分为水溶性部分,不溶于水的部分为脂溶性部分。通过间接酶联免疫法检测样品抑制烟草花叶病毒的活性,通过四甲基偶氮唑盐微量酶反应比色法（MTT法）检测样品抗肿瘤活性,通过形态及ITS rDNA序列法进行菌株鉴定。【结果】两株海洋真菌抑制烟草花叶病毒活性和抗肿瘤的活性均较高。分子鉴定结果显示,两株真菌分别与Penicillium oxalicum 和 Neosartorya fischeri 的同源性极高。菌株0312F1发酵液的水溶性部分具有抗病毒及抗肿瘤活性,菌株1008F1发酵液的脂溶性部分具有抑制烟草花叶病毒活性,而水溶性部分具有抗肿瘤活性。【结论】菌株0312F1和菌株1008F1发酵液的提取物抑制烟草花叶病毒的活性部位不同,而抗肿瘤活性部位相同。菌株0312F1发酵液提取物的水溶性活性部位对肝癌细胞BEL-7404的抑制效果比对胃癌细胞SGC-7901的抑制效果明显,而菌株1008F1发酵液提取物的水溶性活性部位对胃癌细胞SGC-7901的抑制效果比对肝癌细胞BEL-7404的抑制效果明显。     

水稻条纹病毒蛋白与核酸的特性

提纯的水稻条纹病毒（云南宜良分离物）在电镜下的形态为多型性,但主要是宽8－10urn,长80－25O的分枝丝状体,有些为直径3urn或8urn的开环环状体,有些为13urn宽,130－190urn长的丝状体,但其基本结构应是直径3urn、长度不等的丝状体。经聚丙烯酸胺凝胶电泳分析,VRNA4编码的病害特异蛋白（SP）分子量为19．9kDa,而VCRNA3编码的外壳蛋白（CP）约为336kDa。在非变性条件下,RSV的4条ssRNAs大小分别为3‘OXIO‘（ssRNAI）、互．2XIc‘（ssR．NAZ）、0．9X10‘（ssRNA3）和0．8X10‘Da（SSRNA4）,有时出现一条大小为0．58X10‘Da的单链RNA（ssRNA）;而4条dsRNAs的分子量分别为4．9X10‘（dsRNAI）、2．8X10‘（dsRNAZ）、20XIOo（dsRNA3）和1．7X10‘D。（dSRNA4）。利用制备电泳分离提纯的外壳蛋白免疫家兔,得到了高特异性的抗血清。A蛋白夹心ELISA检测结果表服RSV－CP与水稻草状矮化病毒（RGSV）CP抗血清有微弱的反应,但与RSV、RGSV的SP抗血清没有反应,而RSV－CP抗血清与RSV．SP及RGSV的SP、CP都无血清学关系,这个结果表明RGSV与RSV之间在进化上具有一定的亲缘关系。     

复眼透镜光学信息保密编码及译码的研究——Ⅰ.昆虫复眼成像特性及编、译码技术原理

本文根据光学并列型和光学重叠型两类昆虫复眼的屈光系统,具有分解和综合二维图像的光学特性,提出了一种新的用复眼透镜实现二维图像光学信息编码和译码的技术原理.利用复眼透镜和一个特制的随机抽样编码的掩模板,可将一幅有序的二维图像(或者文献、资料等)编码形成为一幅无序的,具有良好保密性能的分解编码像,而且,还能将此编码像反演综合再现出原始图像.它不仅实现了对二维图像信息的多通道并行处理,而且还具有传输量大、速度快、保密性强等优点.我们利用此种复眼透镜光学信息编、译码的技术原理,对二维图像的光学信息进行了分解编码记录及综合译码再现.