萤光素酶报告基因在病毒学研究中的应用

萤光素酶是一类在氧气存在下能催化其底物特异性发光的酶,检出灵敏度高、特异性强。萤光素酶催化底物发光因无须外源光的激发,避免了非特异性干扰,具有其他报告基因不可替代的优势。萤光素酶基因作为报告基因已成为医学科学研究领域的重要标记工具,具有良好的应用前景。我们简要综述了萤光素酶报告基因在病毒学研究中的应用进展。     

Conformation and activity ofPhaseolus coccineus var. rubronanus lectin

The conformation of native and denaturedPhaseolus coccineus var. rubronanus lectin was studied by circular dichroism (CD) and correlated to the hemagglutinating activity. The far-UV CD spectrum at 25°C showed a broad, negative band around 223 nm and a positive one at 196 nm. CD data analysis of the lectin indicated a -sheet-rich protein. At high temperatures, the spectrum was blue-shifted with increasing magnitude; these changes correlated well with the loss of the activity. The conformation of lectin betweenpH 2 and 10 remained essentially unchanged. AtpH 13 the CD spectrum resembled that of unordered form with a negative band near 200 nm and the activity was completely lost. The denatured lectin in 6 M guanidine hydrochloride would be renatured upon diluting the denaturant to 0.75 M; the changes in CD spectrum again correlated well with the loss of the activity. The effect of sodium dodecyl sulfate on the lectin was drastic; it sharply increased thea-helix at the expense of the -sheet and reduced the activity; the changes reached a plateau above 20 mM surfactant.     

A Study on the Morphology of Foliar Trichomes of Evergreen Oaks (Quercus) in China and Its Implication in Taxonomy

Most of the evergreen oaks (Quercus L.) are endemic to China and distributed in a large moutainous area of southwestern China at an altitude of 2600-4000m. The delimitation of sections and species in the group has not been satisfactorily solved. The foliar trichomes are very an important character in identifying species of oaks. As a result of observation on 17 species and 2 varieties of evergreen oaks in China under scanning electron microscope, ten types of foliar trichomes are recognized: Simpleuniseriate, Simple-branched, Bulbous, Rosulate, Solitary, Stipitate-fasciculate, Fasciculate, Multiradiate, Stellate and Fused-stellate. The first four types fall into glandular trichomes and the last six non-glandular trichomes. The taxa examined have a combination of various types of the trichomes. All the evergreen oaks have non-glandular trichomes on their foliar epidermis, but glandular trichomes occur solely in certain taxa. These two types of foliar trichomes are obviously different in structure and function, which represent different adular trichomes and the last six non-glandular en oaks are divided into two groups: the glandular group and the non-glandular group according to the types of foliar trichomes and it is reasonable to divide the evergreen oaks into two sections: Sect. Suber (Reichenb.) Spach and Sect. Englerianae (A. Camus) Hsu et Jen. Foliar trichomes of the evergreen oaks show a continuity in density from species predominately with glandular trichomes at a high altitude to species solely with non-glandular trichomes at a low elevation. The characters of branching of foliar trichomes, especially the number of branches, can imply to some extent the evolutionary position of a given evergreen species. Considering the types, density and branches of foliar trichomes combined the evolutionary relationships among the evergreen oaks in China are proposed. Q. gilliana is the startpoint, from where evolution took place in two directions: glandular and non-glandular. In the glandular direction envolved are Q. aquifolioides, Q. longispica and Q. guyavaefolia. Q. pannosa is a species with the most types and highest number of glandular trichomes. In non-glandular line aligned are Q. spinosa, Q. senescens, Q. senescens var. muliensis, Q. monimotricha with the reduction of glandular trichomes and increase of non-glandular trichomes. After Q. tungmaiensis no glandular trichomes appear and it solely depends on non-glandular trichomes to protect itself. Q. granchetii is the climax in the non-glandular line with the highest density and number of branches of foliar trichomes. And then some species, such as Q. engleriana, Q. phillyraeoides, have few or no trichomes. Q. dolicholepis, Q. baronii and Q. baronii var. capitata show the close re-lationships because they share fused-stellate trichomes.     

Molecular systematics of threadfin breams and relatives (Teleostei,Nemipteridae)

Threadfin breams and relatives of the family Nemipteridae comprise 69 currently recognized species in five genera. They are found in the tropical and subtropical Indo‐West Pacific and most are commercially important. Using recently developed molecule‐based approaches exploiting DNA sequence variation among species/specimens, this study reconstructed a comprehensive phylogeny of the Nemipteridae, examined the validity of species and explored the cryptic diversity of the family, and tested previous phylogenetic hypotheses. A combined data set (105 taxa from 41 morphospecies) with newly determined sequences from two nuclear genes (RAG1 and RH) and one mitochondrial gene (COI), and a data set with only COI gene sequences (329 newly obtained plus 328 from public databases from a total of 53 morphospecies) were used in the phylogenetic analysis. The latter was further used for species delimitation analyses with two different tools to explore species diversity. Our phylogenetic results showed that all the currently recognized genera were monophyletic. The monotypic genus Scaevius is the sister group of Pentapodus and they together are sister to Nemipterus. These three genera combined to form the sister group of the clade comprising Parascolopsis and Scolopsis. The validity of most of the examined species was confirmed except in some cases. The combined evidence from the results of different analyses revealed a gap in our existing knowledge of species diversity in the Nemipteridae. We found several currently recognized species contain multiple separately evolving metapopulation lineages within species; some lineages should be considered as new species for further assignment. Finally, some problematic sequences deposited in public databases (probably due to misidentification) were also revised in this study to improve the accuracy for prospective DNA barcoding work on nemipterid fishes.     

Detection of Salmonella in food samples by the combination of immunomagnetic separation and PCR assay.

A combination of immunomagnetic separation and polymerase chain reaction (IMS-PCR) was used to detect Salmonella in food samples. Pre-enrichment of samples was combined with filtration through a membrane for the removal of food debris. The IMS-PCR assay combines selective extraction of bacteria by specific antibodies with primer specific PCR amplification that enables to detect Salmonella in non-fatty food samples in 24 h. In comparison with conventional cultural methods, the IMS-PCR is a rapid and specific method. Combined with filtration bags, it partially reduces the negative effects of the food matrix and allows the quick detection of Salmonella cells. The shortened protocols for Salmonella spp. detection described here can improve considerably current methodologies.     

植物根系呼吸代谢及影响根系呼吸的环境因子研究进展

根系呼吸是植物通过活根向环境释放CO2的过程。根系的呼吸作用集物质代谢与能量代谢为一体,构成了地下部代谢的中心。根系呼吸进行顺利与否是衡量植物根系功能和逆境胁迫的重要指标之一,相关代谢研究已成为目前植物生理、生化和生态学等领域的热点。该文对植物根系呼吸途径、呼吸代谢关键酶和中间产物、影响根系呼吸代谢的根域环境因子以及研究进展进行了综述,并对其研究前景进行展望。     

Diversity and composition of understory vegetation in the tropical seasonal rain forest of Xishuangbanna, SW China

Tropical forests vegetation and community research have tended to focus on the tree component, and limited attention has been paid to understory vegetation. Species diversity and composition of the understory of tropical seasonal rain forest were inventoried in a 625 m2 area (for sapling layer) and a 100 m2 area (for herb/seedling layer) in three 1 ha plots. We found 3068 individuals belonging to 309 species, 192 genera and 89 families. The most important family as determined by the Family Importance Value (FIV) was Rubiaceae in both sapling and herb/seedling layers. In terms of Importance Value Index (IVI), the shrub Mycetia gracilis (Rubiaceae) was the most important species in the sapling layer and the pteridophyte Selaginella delicatula (Selaginellaceae) was the most ecological significant species in the herb/seedling layer. Much more vascular plant species were registered in the understory than in the tree layer totaled among the three plots. The species diversity did not differ significantly among the tree layer, sapling layer and herb/seedling layer. Given that we still know little about the understory plant community for growth forms other than trees, the results from the present study indicate that more attention should be paid to the understory vegetation during the decision-making process for biodiversity conservation in the tropical forests.     

三角帆蚌Hc-GSK3β基因鉴定及内壳色性状相关SNP筛选

为了探究三角帆蚌(Hyriopsis cumingii)糖原合成激酶-3β(GSK3β)基因对壳色的影响,研究采用RACE技术获得Hc-GSK3β基因cDNA全长1867 bp,其中包含1261 bp的ORF区编码420个氨基酸, ORF中含有一个S＿TKc结构域,该结构域序列高度保守。组织差异表达分析发现Hc-GSK3β基因在紫色蚌鳃、斧足、内脏团和边缘膜组织中表达量高于白色蚌的表达量(P<0.05),且在斧足和边缘膜表达差异水平达到极显著(P<0.01),而在紫色蚌闭壳肌组织中表达量显著低于白色蚌(P<0.05)。原位杂交(ISH)实验结果显示在三角帆蚌外套膜的外褶、中褶、內褶、背膜区和腹膜区均有阳性信号产生,且在外褶的信号表达较强烈。该基因经重测序比较,共鉴定出6个SNP位点,其中在C+185A位点的CA基因型在紫色蚌的分布频率显著高于白色三角帆蚌(P<0.05);在紫色蚌中, T+341G位点TT基因型三角帆蚌内壳颜色参数b值显著低于TG基因型(P<0.05)。研究表明, Hc-GSK3β基因参与了三角帆蚌壳色形成,筛选的SNP标记可用于三角帆蚌壳...     

甘油三酯酶传感器的研制及应用

将脂肪酶固定在pH玻璃电极上,制成甘油三酯酶传感器.对传感器的制作方法和响应性能进行了研究.在37℃,选择Tris-HCl缓冲溶液(pH 8.5)为测量介质, 所制传感器对甘油三酯的响应线性范围为3.09×10^－6～1.91×10^－3 mol/L,响应斜率为32.7 mV/pC, 响应时间为5～10 min, 使用寿命可达25 d.用研制的传感器测定了人和兔血清中的甘油三酯含量,结果满意.