农杆菌介导的DnMADS2基因转化金钗石斛初步研究

为建立稳定有效的金钗石斛转化体系,进一步研究花发育相关基因的功能,为石斛兰分子育种提供基础,本研究以金钗石斛类原球茎（PLBs）为转化受体,通过农杆菌介导的方法将DnMADS2基因转入金钗石斛。结果表明：用20 mg/L潮霉素筛选4个月后获得抗性PLBs,对其进行HPT基因和DnMADS2基因的PCR检测表明,目的基因已成功整合到PLBs中。获得的转化PLBs在抗性培养基上分化为不定芽后,再经生根壮苗培养获得转化植株。对转化植株进行Southern检测,结果表明,DnMADS2基因已整合到5株金钗石斛转化植株基因组中。据此建立的稳定高效的金钗石斛转化体系和获得的转基因植株,将为DnMADS2基因功能的进一步研究和金钗石斛转基因育种奠定基础。     

水稻秸秆中硅体的光催化活性研究

采用干燥-灼烧-煅烧工艺从水稻秸秆中制备硅体,并对硅体进行表征和光催化活性研究。结果表明,制备的硅体由无定形的微米、纳米二氧化硅颗粒组成,并具有光驱类脱氢酶活性和光催化降解甲基紫的能力。在模拟的光源下,在人工模拟的光源下,硅体催化红四氮唑(TTC)迅速转变成不溶于水的三苯甲簪(TPF),硅体的光驱类脱氢酶活力值达到2622μg TPF ·g-1 ·min-1;光催化降解甲基紫染料的结果表明硅体对甲基紫的去除率2 h内达到94.4%。秸秆中硅体的光催化特性为生物质资源的开发利用提供新途径,同时也对自然界中生物材料结构与功能的研究提供了新的思路。     

60Coγ辐照对霍山石斛悬浮培养原球茎生长和生物碱积累的影响

以霍山石斛原球茎为材料,研究5、10、20和30Gy的60Co γ辐照处理对原球茎悬浮培养生物碱积累的影响。结果表明,60Co γ辐照处理能提高悬浮培养原球茎生物碱含量,且适宜辐照剂量为10Gy。 10Gy处理的原球茎培养36d时,原球茎鲜重为26.54g/瓶,生物碱含量为0.035%,此时培养液pH和原球茎电导率变化较小,培养液环境适合原球茎继续培养;同时辐照处理可促进POD、SOD、CAT和PAL酶活性,抑制PPO酶活性,从而促进石斛原球茎生长和生物碱合成。     

外源一氧化氮对铁皮石斛原球茎生长和多糖积累的影响

以硝普钠（SNP）为一氧化氮（NO）供体,研究了不同浓度的外源NO对铁皮石斛原球茎生长、叶绿素含量、蔗糖合成酶（SS）活性和多糖积累的影响。结果总体表现为低浓度的SNP有利于铁皮石斛原球茎的生长,而高浓度的SNP可以促进多糖的合成。在添加0.50 mmol·L-1SNP的培养基中培养28 d时其干质量比对照高36.9％,总叶绿素含量在14 d时为对照的1.33倍;在添加1.00 mmol·L-1 SNP的培养基中培养7 d时其多糖含量为对照的1.59倍,同时SS活性显著升高。综合多糖产量来看,0.50 mmol·L-1SNP效果最佳,在处理期间显著高于其他处理,且对其干质量、叶绿素含量、SS活性和多糖积累均有促进作用。添加NO清除剂（cPTIO）后,铁皮石斛原球茎的生长、SS活性和多糖合成受到抑制。     

A New Disease of Cherry Plum Tree with Yellow Leaf Symptoms Associated with a Novel Phytoplasma in the Aster Yellows Group

A novel phytoplasma was detected in a cherry plum（Prunus cerasifera Ehrh） tree that mainly showed yellow leaf symptom. The tree was growing in an orchard located in Yangling District, Shaanxi Province, China. The leaves started as chlorotic and yellowing along leaf minor veins and leaf tips. Chlorosis rapidly developed to inter-veinal areas with the whole leaf becoming pale yellow in about 1-4 wk. Large numbers of phytoplasma-like bodies（PLBs） were seen under transmission electron microscopy. The majority of the PLBs was spherical or elliptical vesicles, with diameters in range of 0.1-0.6 μm, and distributed in the phloem cells of the infected tissues. A 1 246-bp 16 S ribosomal RNA（rRNA） gene fragment was amplified from DNA samples extracted from the yellow leaf tissues using two phytoplasma universal primer pairs R16mF2/R16mR1 and R16F2n/R16R2. Phylogenetic analysis using the 16 S rRNA gene sequence suggested that the phytoplasma associated with the yellow leaf symptoms belongs to a novel subclade in the aster yellows（AY） group（16SrI group）. Virtual and actual restriction fragment length polymorphism（RFLP） analysis of the 16 S rRNA gene fragment revealed that the phytoplasma was distinguishable from all existing 19 subgroups in the AY group（16SrI） by four restriction sites, Hinf I, Mse I, Sau3 A I and Taq I. The similarity coefficients of comparing the RFLP pattern of the 16 S rRNA gene fragment of this phytoplasma to each of the 19 reported subgroups ranged from 0.73 to 0.87, which indicates the phytoplasma associated with the cherry plum yellow leaf（CPYL） symptoms is probably a distinct and novel subgroup lineage in the AY group（16SrI）. In addition, the novel phytoplasma was experimentally transmitted to periwinkle（Catharanthus roseus） plants from the tree with CPYL symptoms and then back to a healthy 1-yr-old cherry plum tree via dodder（Cuscuta odorata） connections.     

GM2 Gangliosidosis in Shiba Inu Dogs with an In‐Frame Deletion in HEXB

Consistent with a tentative diagnosis of neuronal ceroid lipofuscinosis (NCL), autofluorescent cytoplasmic storage bodies were found in neurons from the brains of 2 related Shiba Inu dogs with a young‐adult onset, progressive neurodegenerative disease. Unexpectedly, no potentially causal NCL‐related variants were identified in a whole‐genome sequence generated with DNA from 1 of the affected dogs. Instead, the whole‐genome sequence contained a homozygous 3 base pair (bp) deletion in a coding region of HEXB. The other affected dog also was homozygous for this 3‐bp deletion. Mutations in the human HEXB ortholog cause Sandhoff disease, a type of GM2 gangliosidosis. Thin‐layer chromatography confirmed that GM2 ganglioside had accumulated in an affected Shiba Inu brain. Enzymatic analysis confirmed that the GM2 gangliosidosis resulted from a deficiency in the HEXB encoded protein and not from a deficiency in products from HEXA or GM2A, which are known alternative causes of GM2 gangliosidosis. We conclude that the homozygous 3‐bp deletion in HEXB is the likely cause of the Shiba Inu neurodegenerative disease and that whole‐genome sequencing can lead to the early identification of potentially disease‐causing DNA variants thereby refocusing subsequent diagnostic analyses toward confirming or refuting candidate variant causality.     

RESULTS OF COMPUTED TOMOGRAPHY IN DOGS WITH SUSPECTED WOODEN FOREIGN BODIES

Detection of wooden foreign bodies in dogs can be challenging. A retrospective, cross‐sectional study was done to describe computed tomographic (CT) signs associated with wooden foreign bodies, and to estimate the accuracy of CT for detection of wooden foreign bodies. Patient records and CT images were reviewed for 72 dogs that had a history of suspected stick injury and CT of the affected body part, or possible wooden foreign object reported on CT, and had surgical exploration during the same period of hospitalization. Duration of clinical signs was acute in 48 (67%) dogs and chronic in 24 (33%). Wood was removed from 55 dogs, including a piece of a tree or shrub in 33 (60%) instances, kebab stick in 8 (15%), piece of bamboo garden cane in 2 (4%), cocktail stick in 2 (4%), thorn in 1 (2%), and unidentified wood in the remaining nine instances. Based on review of CT images with knowledge of the surgical findings, sensitivity of CT for wooden foreign bodies was 79% (95% CI 65%–89%), specificity 93% (78%–98%), positive likelihood ratio 11.5 (2.9–44.1), and negative likelihood ratio 0.23 (0.13–0.41). Wooden foreign bodies were predominantly rectangular or linear, with median length 48 mm (range 2–270 mm), median thickness 3 mm (range 1–22 mm), and median attenuation 111 HU (range ?344 to +640 HU). A CT finding of gas in soft tissues was significantly associated with acute cases, whereas suspected foreign material, cavitary lesions, fat stranding, and periosteal reaction on adjacent bones were associated with chronic cases.     

New insight into puroindoline function inferred from their subcellular localization in developing hard and soft near-isogenic endosperm and their relationship with polymer size of storage proteins

Wheat endosperm texture is correlated with one major locus, Ha, located on the short arm of chromosome 5D, which comprises several genes among which are two puroindoline genes, Pina and Pinb. In this study, we used two near-isogenic lines, the hard-textured line lacking Pina and the soft-textured line containing both Pina and Pinb wild-type genes. Hard and soft endosperms were observed at four kernel developmental stages, from 180 °Cd to 750 °Cd. Puroindolines were located within protein bodies at the onset of prolamin accumulation by transmission electron microscopy and immunolabelling. Ab initio modeling showed a closer structural relationship between puroindolines and 2S storage proteins from dicots than between puroindolines and other cysteine-rich wheat proteins, i.e. LTP and amylase inhibitors. Compared to the soft line, storage protein polymers in the hard line exhibited higher molecular mass (increase of from 6 to 93%) and polydispersity indices (increase of from 26 to 63%) over the course of the 4-year experiment. This suggests that puroindolines might impact the aggregation of storage proteins. Finally, these data pave the way for investigation of the role of protein–protein interactions in the texture of wheat endosperm.     

核桃种子油体发育及不同品种种子子叶油体特征差异分析

【目的】通过观察不同核桃品种种子油体发育过程,分析其成熟期子叶油体特征,旨在寻找核桃种子油体合成的起始时间及发生位置,了解不同品种种子在子叶油体特征上的差异及其与含油率间的关系,加深对新疆早实核桃品种种子细胞超微结构的认识。【方法】以新疆早实核桃品种‘温185’和‘新新2号’为试验材料,采用索式脂肪测定仪检测核桃种子脂肪含量,并运用透射电子显微镜技术观察种子发育进程中细胞器的发育消解及油体发育过程。【结果】花后30 d,核桃种子胚中开始存在单独的细胞,各细胞壁之间界限清晰;单独细胞中开始形成各种细胞器。花后50 d,细胞内的细胞器更为丰富,同时内质网数量不断增多,且以条状为主。花后60 d,内质网两端开始膨胀增厚,零星出现油体,随后种子胚中的油体数量不断增加直至成熟。细胞中的内质网数量于花后90 d开始减少,其余各种细胞器于花后110 d开始消解。花后120 d,细胞被油体和蛋白体填满。子叶细胞中的油体积累滞后于胚中的油体积累,花后60 d才开始形成单独细胞且细胞内已出现各种细胞器,同时子叶细胞中的内质网已开始膨胀增厚。至花后80 d,内质网才开始分泌小泡,形成油体,晚于胚20 d。成熟期核桃种子子叶细胞完全被油体和少量蛋白体充实,油体呈椭球体或不规则多面体,较少为球体,且油体个体间的形态与大小特征存在较大差异。种子含油率相对较高的‘温185’子叶贮藏细胞内油体数量较种子含油率相对较低的‘新新2号’少,但其直径和截面积之和却较大,且在两个品种间分别存在极显著（P＜0.01）和显著（P＜0.05）差异。【结论】核桃种子胚和子叶中的油体主要发生于内质网,在花后60 d开始积累,且子叶中油体的积累滞后于胚,二者不具有同步性。成熟后种子子叶贮藏细胞内油体直径大小和截面积之和是导致‘温185’与‘新新2号’种仁含油率产生差异的内在主要因素。     

The importance of being natural in a human‐altered riverscape: role of wetland type in supporting habitat heterogeneity and the functional diversity of vegetation

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