盐胁迫对玉米叶片叶肉细胞生物膜超微结构的影响

研究了NaCl胁迫对玉米叶肉细胞生物膜超微结构的影响. 结果表明：NaCl胁迫破坏了玉米叶片叶肉细胞生物膜的正常结构,50 mmol·L^-1 NaCl处理胁迫下,玉米叶肉细胞核膜,线粒体膜,细胞膜,叶绿体膜,液泡膜都受到不同程度的破坏,叶绿体基粒类囊体膨胀,间质片层空间增大,片层紊乱。100 mmol·L^-1 NaCl处理胁迫下,质膜,液泡膜,线粒体,叶绿体都受到严重的破坏。细胞质膜破坏,破损的叶绿体充斥在细胞间隙中;叶绿体外膜破坏,甚至解体消失,叶肉细胞中充满膜结构,基粒排列方向改变,垛叠层数减少,基粒和基质片层界限模糊不清,有的基粒解体消失,甚至叶绿体完全解体;核膜破坏、解体,核中的染色质高度凝缩;线粒体的数量增多,线粒体膜破坏,脊的数量减少,甚至整个线粒体破损解体;液泡膜破坏;由于各种生物膜的破坏,使细胞内充满许多囊状小泡、多泡体或斑层小体;叶肉细胞发生严重的质壁分离,严重时发生细胞壁断裂;甚至整个细胞溶解。     

Habitat use by fishes after tidal reconnection of an impounded estuarine wetland in the Indian River Lagoon,Florida (USA)

Most of the wetlands located along the Indian River Lagoon (IRL) ineast-central Florida (USA) have been impounded since the 1950's and1960's to reduce mosquito reproduction. Impounded marsh (i.e.,impoundment) dikes physically separate the wetlands from the estuary toallow artificial flooding of the impoundments during the mosquito breedingperiod (May to October). Presently, Rotational ImpoundmentManagement (RIM) is the preferred impoundment management techniquein the IRL. Impoundments maintained under RIM have culverts installedthrough the dikes which are kept closed during the mosquito breedingseason (to control mosquitos) and are allowed to remain open for theremainder of the year (to allow tidal flow). A 24.3 ha impoundment8 km north of Sebastian Inlet that had been isolated from the IRL for over39 years was studied for 12 months to determine habitat use by fishes aftertidal reconnection and the implementation of RIM. Fish sampling wasconducted with a seine in the perimeter ditch and with clover and minnowtraps in the upper marsh and tidal creek areas of the impoundment. Waterlevel, impoundment bottom topography, and the seasonal nursery functionof the impoundment were factors that contributed to observed patterns offish habitat use during the study. Within the first 15 weeks of perimeterditch sampling, an increase from 9 to 40 species was observed. Transientspecies used the perimeter ditch almost exclusively and entered theimpoundment primarily during the spring open period. Juvenile Pogonias cromis (Linnaeus), Elops saurus Linnaeus, Centropomusundecimalis (Bloch), and Megalops atlanticus Valenciennes were themost abundant recreationally important species, respectively. Habitat useby the most abundant resident species (Gambusia holbrooki Girard,Poecilia latipinna (Lesueur), Cyprinodon variegatus Lacepède, andFundulus confluentus Goode & Bean) was influenced primarily bywater level fluctuations. Resident species used the upper marsh and tidalcreek habitats during summer flooded periods and the cyprinodontids leftthe interior surface of the impoundment last as water levels decreased. Thisstudy is the first to document the recovery of fish populations in areconnected impoundment north of Sebastian Inlet using both active andpassive sampling techniques.     

Expression of a bacterial carotene hydroxylase gene (crtZ) enhances UV tolerance in tobacco

Carotenoids are essential components of the photosynthetic apparatus involved in plant photoprotection. To investigate the protective role of zeaxanthin under high light and UV stress we have increased the capacity for its biosynthesis in tobacco plants (Nicotiana tabacum L. cv. Samsun) by transformation with a heterologous carotenoid gene encoding -carotene hydroxylase (crtZ) from Erwinia uredovora under constitutive promoter control. This enzyme is responsible for the conversion of -carotene into zeaxanthin. Although the total pigment content of the transgenics was similar to control plants, the transformants synthesized zeaxanthin more rapidly and in larger quantities than controls upon transfer to high-intensity white light. Low-light-adapted tobacco plants were shown to be susceptible to UV exposure and therefore chosen for comparative analysis of wild-type and transgenics. Overall effects of UV irradiation were studied by measuring bioproductivity and pigment content. The UV exposed transformed plants maintained a higher biomass and a greater amount of photosynthetic pigments than controls. For revelation of direct effects, photosynthesis, pigment composition and chlorophyll fluorescence were examined immediately after UV treatment. Low-light-adapted plants of the crtZ transgenics showed less reduction in photosynthetic oxygen evolution and had higher chlorophyll fluorescence levels in comparison to control plants. After 1 h of high-light pre-illumination and subsequent UV exposure a greater amount of xanthophyll cycle pigments was retained in the transformants. In addition, the transgenic plants suffered less lipid peroxidation than the wild-type after treatment with the singlet-oxygen generator rose bengal. Our results indicate that an enhancement of zeaxanthin formation in the presence of a functional xanthophyll cycle contributes to UV stress protection and prevention of UV damage.     

东北水生植物区系与周缘地区水生植物区系关系的分析

本文在野外采集、查阅标本和文献考证的基础上,对东北地区水生植物区系与周缘地区水生植物区系的关系进行了初步分析。由于日本在地史起源上曾与大陆相连,且现代气候环境与东北地区的相似,故两者间水生植物的相似性系数最高O在更新世前古嫩辽河与结雅河相连通,使东北与远东地区间的水生植物得以相互交流,同时两区还保存有一些第三纪植物于遗种类,但因远东地区缺少东北暖温带气候,故一些东北产的暖温带种类未能分布该区,使其与东北水生植物种类相似性系数位于第二位。印度次大陆、澳大利亚、东南亚和非洲因与东北地区位于不同的气候带中,故水生植物种类相似性系数较低。在国内各地区中,以华北地区与东北地区水生植物的相似性系数最高,因两者过去同属古黄河水系,近代又接壤;相反,以与华南、台湾和海南岛的水生植物种类相似性系数最低。因相互间即存地理隔离,又无水系相通。     

Opportunities for gene transfer from transgenic oilseed rape (Brassica napus) to related species

Before novel transgenic plant genotypes are grown outside containment facilities and evaluated under field conditions, it is necessary to complete a risk assessment to consider the possible consequences of that release. An important aspect of risk assessment is to consider the likelihood and consequences of the transgene being transferred by cross-pollination to related species, including other crops, weeds and ruderal populations. The purpose of this report is to review the literature to assess the ease with whichBrassica napus can hybridize with related species. The evidence for hybridization is considered at three levels: a) by open pollination, b) by hand pollination and c) by the use ofin vitro ovule and embryo rescue techniques; and also examines the fertility and vigour of the F₁, F₂ and backcross generations. Four species are reported to hybridize withB. napus by open pollination:B. rapa andB. juncea using fully fertile parents; andB. adpressa andR. raphanistrum using a male-sterileB. napus parent. Seventeen species are reported to form hybrids (including the four species above) withB. napus when pollination is carried out manually. At least 12 of these species were unable to form F₂ progeny, and eight were unable to produce progeny when the F₁ was backcrossed to one of the parental species. Many factors will influence the success of hybridization under field conditions, including: distance between the parents, synchrony of flowering, method of pollen spread, specific parental genotypes used, direction of the cross and the environmental conditions. Even where there is a possibility of hybridization betweenB. napus and a related species growing in the vicinity of a release, poor vigour and high sterility in the hybrids will generally mean that hybrids and their progeny will not survive in either an agricultural or natural habitat.     

广东地区三种木本植物抗大气污染能力的比较

研究了工业污染区(佛山市小塘镇五星WX)和相对清洁区(广州华南植物园BG)生长的3种木本植物光叶山矾(Symplocos lancifolia)、银柴(Aporosa chinensis)和窿缘桉(Eucalyptus exserta)叶片对酸碱缓冲能力的差别。工业污染区3种植物的细胞液pH均比相对清洁区的低,光叶山矾与银柴对酸和碱的缓冲能力强于窿缘桉。用外源NaHSO3处理,植物叶片的光合放氧、Fv／Fm、Fv／Fo和ФPsⅡ都有不同程度的下降。其中,窿缘桉下降的幅度最大,说明其抗大气污染的能力不如光叶山矾和银柴,同时也证明了用缓冲能力作为一种评价植物抗污能力的指标具有一定的科学性。     

Genetic architecture for normal and novel host-plant use in two local populations of the herbivorous ladybird beetle, Epilachna pustulosa

Trade-offs in host-plant use are thought to promote the evolution of host specificity. However, usually either positive or no genetic correlations have been found. Whereas factors enhancing variation in overall viability have been claimed to mask negative genetic correlations, alternative hypotheses emphasize the sequential changes in genetic correlation in the course of host-range evolution. In this study, the genetic architectures of performances on different hosts were compared in two populations of the herbivorous ladybird beetle, Epilachna pustulosa, using three host plants, one being normal for both, one novel for only one population, and the other novel for both populations. The genetic correlations between larval periods on normal hosts were significantly positive whereas those between normal and novel hosts were not different from zero. There was no evidence for reduced genetic variation on the normal host-plants. These results suggest that the host-range is not restricted by the antagonistic genetic associations among exploitation abilities on different plant species, but rather that selection of different host-plants may improve the coordination between genes responsible for the use of different plants.     

C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves

Attempts are being made to introduce C₄ photosynthetic characteristics into C₃ crop plants by genetic manipulation. This research has focused on engineering single‐celled C₄‐type CO₂ concentrating mechanisms into C₃ plants such as rice. Herein the pros and cons of such approaches are discussed with a focus on CO₂ diffusion, utilizing a mathematical model of single‐cell C₄ photosynthesis. It is shown that a high bundle sheath resistance to CO₂ diffusion is an essential feature of energy‐efficient C₄ photosynthesis. The large chloroplast surface area appressed to the intercellular airspace in C₃ leaves generates low internal resistance to CO₂ diffusion, thereby limiting the energy efficiency of a single‐cell C₄ concentrating mechanism, which relies on concentrating CO₂ within chloroplasts of C₃ leaves. Nevertheless the model demonstrates that the drop in CO₂ partial pressure, pCO₂, that exists between intercellular airspace and chloroplasts in C₃ leaves at high photosynthetic rates, can be reversed under high irradiance when energy is not limiting. The model shows that this is particularly effective at lower intercellular pCO₂. Such a system may therefore be of benefit in water‐limited conditions when stomata are closed and low intercellular pCO₂ increases photorespiration.     

Expression,surface immobilization,and characterization of functional recombinant cannabinoid receptor CB2

Human peripheral cannabinoid receptor CB₂, a G protein-coupled receptor (GPCR) involved in regulation of immune response has become an important target for pharmaceutical drug development. Structural and functional studies on CB₂ may benefit from immobilization of the purified and functional receptor onto a suitable surface at a controlled density and, preferably in a uniform orientation. The goal of this project was to develop a generic strategy for preparation of functional recombinant CB₂ and immobilization at solid interfaces. Expression of CB₂ as a fusion with Rho-tag (peptide composed of the last nine amino acids of rhodopsin) in E. coli was evaluated in terms of protein levels, accessibility of the tag, and activity of the receptor. The structural integrity of CB₂ was tested by ligand binding to the receptor solubilized in detergent micelles, captured on tag-specific monoclonal 1D4 antibody-coated resin. Highly pure and functional CB₂ was obtained by sequential chromatography on a 1D4- and Ni-NTA-resin and its affinity to the 1D4 antibody characterized by surface plasmon resonance (SPR). Either the purified receptor or fusion CB₂ from the crude cell extract was captured onto a 1D4-coated CM4 chip (Biacore) in a quantitative fashion at uniform orientation as demonstrated by the SPR signal. Furthermore, the accessibility of the extracellular surface of immobilized CB₂ and the affinity of interaction with a novel monoclonal antibody NAA-1 was studied by SPR. In summary, we present an integral strategy for purification, surface immobilization, ligand- and antibody binding studies of functional cannabinoid receptor CB₂.     

萎缩芽胞杆菌CKL1促盐胁迫下燕麦生长活性及其功能基因分析

【背景】青海省特殊生境孕育了特殊微生物资源。【目的】探究适合生活于高原生境的芽胞杆菌菌源。【方法】采用平板对峙法、显色法对萎缩芽胞杆菌（Bacillus atrophaeus） CKL1的拮抗、产吲哚乙酸活性进行测定,并检测耐低温、耐盐性及菌株对盐胁迫下燕麦品种（Avena sativa）“青燕1号”种子萌发、幼苗生长效应及叶绿素、脯氨酸、丙二醛的含量变化,利用二代测序技术对菌株进行基因组测序并分析相关功能基因。【结果】菌株CKL1对禾谷镰孢菌（Fusarium graminearum）、锐顶镰孢菌（Fusarium acuminatum）表现出显著的拮抗活性（抑菌圈直径>15 mm）;与Salkowski比色液反应变红,能在NaCl浓度为13%的LB培养基及4℃低温下生长,表现出一定的产吲哚乙酸、耐盐及耐低温活性;盐胁迫下,菌株CKL1对“青燕1号”种子萌发及幼苗生长具有显著促进作用,叶绿素及脯氨酸含量显著增加,丙二醛含量下降,增强了燕麦的抗盐性。菌株CKL1基因组全长为14 281 280 bp,与GO功能数据库比对注释到3 303个功能基因;基因组编码与脂肽类化合物itur...