Photosynthetic response of white spruce families to drought stress     

F.?J.?BigrasEmail author 《New Forests》2005,29(2):135-148

In the context of climate change, an increased frequency of drought stresses might occur at a regional scale in boreal forests. To assess photosynthetic responses to drought treatment, seedlings of 12 open-pollinated families of white spruce (Picea glauca (Moench) Voss) differing in their growth performance were grown in a controlled environment. Gas exchange and chlorophyll fluorescence parameters as well as shoot xylem water potential (WP) were measured for 21 successive days after watering was stopped. Net photosynthesis decreased as stomatal conductance decreased. Net photosynthesis was not affected by drought until WP reached –2.0 MPa when stomata were closed. Initial fluorescence (F and basic fluorescence after induction (F00) were not affected by drought. A progressive decrease in maximal (Fm) and variable fluorescences (Fv), maximum photosystem II (PS II) efficiency (Fv = Fm), effective quantum yield of PS II (FII), photochemical efficiency of open PS II (Fp), and photochemical quenching (qP) was observed at WP < - 1.0 MPa, whereas non-photochemical quenching (qN) remained high throughout the drought treatment. White spruce families with inferior growth performance showed higher values of Fm, Fv, Fv = Fm, Fp, and qN at WP< - 2.0MPa. The results indicated that chlorophyll fluorescence variables can be used as drought markers in relation to present or predicted climate conditions. These could be used for selecting planting stock adapted to drought periods or dry environments. These markers showed that slow-growing genotypes are better adapted to drought conditions than intermediate or fast-growing genotypes in present and predicted drought conditions.  相似文献   

Efficacy of the organic-certified insecticide Diatect II against the boll weevil (Anthonomus grandis) in cotton     

Sappington TW 《Pest management science》2002,58(10):1038-1042

The efficacy of the organic insecticide Diatect II against boll weevil (Anthonomus grandis Boheman) in cotton (Gossypium hirsutum L) in the Lower Rio Grande Valley of Texas were assessed in small-plot field trials and greenhouse cage tests using azinphos-methyl treatments as a standard for comparison. Plastic sheets were placed in the furrows of the treated plots to retrieve boll weevils which dropped from the plants after being killed by the insecticides. Samples of live weevils taken by a tractor-mounted vacuum sampler revealed a modest, but significant, reduction in boll weevil populations in Diatect II plots. However, samples of dead weevils indicated that this reduction was due to movement of weevils out of the plots rather than to mortality. This interpretation is supported by greenhouse cage studies, where mortality in Diatect II treated cages was no greater than that in untreated control cages. The effects of insecticide treatments in small plots can be confounded easily and quickly by interplot movement of target insects. Although the relative effects of various compounds can usually be assessed by sampling the populations in plots soon after treatment, the best measure of efficacy is obtained by directly sampling insects that have died in the plot. This parameter is insulated from the effects of interplot movement, unless the toxicant is slow to immobilize the target insect. Taken together, our results indicate little efficacy by Diatect II against boll weevil under our test conditions.  相似文献   

Herbicidal action of 2-hydroxy-3-alkyl-1,4-naphthoquinones     

Jewess PJ  Higgins J  Berry KJ  Moss SR  Boogaard AB  Khambay BP 《Pest management science》2002,58(3):234-242

The main mode of herbicidal activity of 2-hydroxy-3-alkyl-1,4-naphthoquinones is shown to be inhibition of photosystem II (PSII). The herbicidal and in vitro activities have been measured and correlated with their (Log)octanol/water partition coefficients (Log Ko/w). The length of the 3-n-alkyl substituent for optimal activity differed between herbicidal and in vitro activity. The maximum in vitro activity was given by the nonyl to dodecyl homologues (Log Ko/w between 6.54 and 8.12), whereas herbicidal activity peaked with the n-hexyl compound (Log Ko/w = 4.95). The effect of chain branching was also investigated using isomeric pentyl analogues substituted at position 3. All exhibited similar levels of in vitro activities but herbicidal activities differed, albeit moderately, with the exception of one analogue that was much less phytotoxic. Other modes of action were also investigated using two representative compounds. They did not show any activity on photosystem I or mitochondrial complex I, or generate toxic oxygen radicals by redox cycling reactions. Only moderate activity was found against mitochondrial complex III from plants, in contrast to much higher corresponding activity using an insect enzyme.  相似文献   

基于ILASII编目工作效率的应用实践   总被引：3，自引：0，他引：3  

袁红梅 《农业图书情报学刊》2005,17(11):162-164

从ILASII系统出发,通过设置相应参数,合理安排工作流程,减少了编目工作的重复环节,实现多人同时验收编目加工图书,从而提高了图书编目工作效率。  相似文献   

Role of nucleolin in Ang II-induced phenotypic transformation of vascular smooth muscle cells     

FANG Li  HUANG Qing  Zhang Yin-zhuang  HUANG Fang  YUAN Cong  LIU Wei-wei 《园艺学报》2019,35(10):1753-1761

AIM: To investigate the effect of nucleolin on angiotensin II (Ang II)-induced phenotypic transformation of vascular smooth muscle cells (VSMCs). METHODS: Ang II was used to induce the phenotypic transformation of VSMCs. The spatial and temporal expression patterns of nucleolin, and the effects of Ang II on the expression of VSMC phenotypic transformation markers α-smooth muscle actin (α-SMA), calponin, smooth muscle protein 22 α (SM22α) and osteopontin (OPN) were investigated. The techniques of gene over-expression and RNA interference were used to assess the effect of nucleolin on the expression of Ang II-mediated VSMC phenotypic transformation markers. RESULTS: The expression of α-SMA, SM22α and calponin at the mRNA and protein levels was gradually decreased by Ang II stimulation, while the expression of OPN at mRNA and protein levels was gradually increased. The expression of nucleolin was gradually up-regulated in the VSMCs treated with Ang II at different concentrations for various duration (P<0.05). Ang II induced nucleolin translocation from the nucleus to cytoplasm. Over-expression of nucleolin promoted the VSMC phenotypic transformation induced by Ang II. Down-regulation of nucleolin suppressed the promotion of phenotypic transformation. CONCLUSION: Nucleolin promotes Ang II-induced phenotypic transformation of VSMCs, and its mechanism may be related to its function of cytoplasmic translocation.  相似文献   

Role of AT₁R-CaN signaling pathway in regulation of Nav1.5 protein expression in hypertrophic ventricular myocytes from neonatal rats     

DENG Na  XIA Gui-ling  YANG Long  HE Jiong-hong  LI Jun  TIAN Yin  YANG Ying 《园艺学报》2017,33(2):221-226

AIM: To investigate the effect of angiotensin II type 1 receptor (AT₁R)-calcineurin (CaN) signaling pathway on the expression of sodium current channel Nav1.5 at mRNA and protein levels in the hypertrophic ventricular myocytes from neonatal rats.METHODS: The ventricular myocytes were isolated from the ventricles of 1-day-old neonatal Sprague-Dawley rats and were divided into 4 groups according to different drug intervention as control group, phenylephrine (PE) group, losartan (Los)+PE group and cyclosporin A (CsA)+PE group. The method of RNA interference mediated by adenovirus carrying short hairpin RNA (shRNA) was used to knock down the gene which encodes the beta subtype of CaN A subunit (CnAβ) and the cells were divided into 4 groups as Ad-Null group, Ad-Null+PE group, Ad-CnAβshRNA1 group and Ad-CnAβshRNA1+PE group. The mRNA expression of brain natriuretic peptide (BNP), β-myosin heavy chain (β-MHC) and Nav1.5 was detected by RT-qPCR. The protein levels of CnAβ and Nav1.5 in the whole-cell extracts were determined by Western blot analysis.RESULTS: Treatment of the neonatal rat ventricular myocytes with PE for 24 h increased the protein-to-DNA ratio and the mRNA expression of BNP and β-MHC. The size of the cell surface was also increased after PE treatment. Treatment of the cells with PE increased the protein expression of CnAβ, and reduced the protein expression of Nav1.5. Both Los and CsA prevented those effects of PE. The mRNA expression of Nav1.5 was reduced by PE, and no significant difference of Nav1.5 mRNA expression among PE group, Los+PE group and CsA+PE group was observed. Silencing of CnAβ in the neonatal rat ventricular myocytes using Ad-CnAβshRNA1 inhibited the ability of PE to increase the mRNA expression of BNP, and diminished the ability of PE to reduce the protein expression of Nav1.5.CONCLUSION: AT₁R-CaN signaling pathway participates in regulating protein expression of Nav1.5 in the hypertrophic ventricular myocytes from neonatal rats.  相似文献   

两个玉米品种维管束鞘叶绿体的非光化学淬灭对干旱胁迫的响应     

刘文娟  常丽娟  岳丽杰  宋君  张富丽  王东  吴佳蔚  郭灵安  雷绍荣 《中国农业科学》2020,53(8):1532-1544

【目的】光系统II的非光化学叶绿素荧光淬灭是高等植物响应环境变化最快速的光保护机制,玉米具备叶肉和维管束鞘2种叶绿体结构,本研究通过比较2个玉米品种的光合耐旱能力,探究维管束鞘叶绿体的非光化学淬灭对玉米耐旱性的意义。【方法】以成单30和仲玉3号2个玉米品种为研究材料,设置土壤相对含水量为70%—80%田间持水量（FWC）（充足浇水,对照）、50%—60% FWC（中度干旱胁迫）和35%—45% FWC（重度干旱胁迫）3个土壤水分梯度处理。测定玉米叶片的水分状况、叶绿素含量、活性氧积累、质膜透性和气体交换等参数;应用叶绿素荧光动力学显微成像观测,比较玉米叶肉和维管束鞘叶绿体的叶绿素荧光参数Fv/Fm和NPQ;通过免疫印迹法,分析玉米叶肉和维管束鞘细胞光系统II亚基S（PsbS）稳态水平的变化差异;采用蓝-绿胶温和电泳分离,检测玉米光系统II蛋白复合体的水平。【结果】干旱胁迫导致叶片气孔导度和蒸腾速率下降,2个玉米品种间没有明显差异。但成单30在重度干旱下表现出更好的水分状况、更低的活性氧损伤以及更高的光合速率。玉米叶肉和维管束鞘叶绿体的NPQ水平及PsbS蛋白含量受干旱诱导明显上升,维管束鞘中的上升更显著,成单30表现尤为突出。不同于仲玉3号光系统II蛋白复合体水平的下降,重度干旱胁迫后,成单30的捕光蛋白三聚体水平在叶肉和维管束鞘细胞中均有所升高。【结论】2个玉米品种的光合机构对干旱胁迫的气孔响应能力相当,但相较仲玉3号,成单30的维管束鞘叶绿体具备更优越的非光化学淬灭能力,这对其更强的非气孔限制的光合耐旱性具有积极意义。  相似文献   

Cloning of a cDNA encoding the tail region of non-muscle myosin II from the mantle tissue of scallop <Emphasis Type="Italic">Patinopecten yessoensis</Emphasis>     

Yasushi Hasegawa  Yohko Ikeda 《Fisheries Science》2008,74(5):1201-1203

  相似文献   

全生育期UV-B辐射增强对棉花生长及光合作用的影响   总被引：2，自引：1，他引：2  

祁虹  段留生  王树林  王燕  张谦  冯国艺  杜海英  梁青龙  林永增 《中国生态农业学报》2017,25(5):708-719

植物光合系统是UV-B辐射最初和最重要的作用靶标。本文在大田条件下进行紫外灯照射处理,研究全生育期UV-B辐射增强(高于环境20%和40%)对棉花形态、干物质积累、光合色素和产量的影响,并通过分析棉花主茎功能叶片的气体交换参数和叶绿素荧光参数,探讨UV-B辐射增强影响棉花光合作用的机制。结果表明,UV-B辐射增强抑制了棉花生长和干物质积累,籽棉产量显著降低,且UV-B辐射越强,抑制作用越明显。随UV-B辐射的增强,棉花主茎功能叶的净光合速率(P_n)在各生育期均显著降低,叶绿素含量呈先升高后降低趋势,气孔导度(Gs)和蒸腾速率(Tr)未发生变化,胞间CO_2浓度(Ci)反而升高,说明P_n下降主要由非气孔限制因素造成。对叶绿素荧光参数的分析表明,PSⅡ的最大光化学量子产率(F_v/F_m)、实际光化学量子效率(ΦPSII)、线性电子传递速率(ETR)和光化学淬灭系数(qP)随着UV-B辐射的增强而降低,非光化学猝灭系数(NPQ)则显著升高,且各叶绿素荧光参数与Pn变化均显著相关;慢速弛豫NPQ(NPQS)及其在NPQ中的比例均随UV-B辐射的增强而显著提高,表明PSⅡ反应中心受损,光化学效率降低。以上结果证明,全生育期UV-B辐射增强降低了棉花的光合叶面积、叶绿素含量和净光合速率,引起棉花生长与物质积累受抑,产量降低。UV-B辐射增强引起的光合速率下降与PSⅡ反应中心遭到破坏密切相关。  相似文献   

Synthesis and regulation of 17α-hydroxy-20β-dihydroprogesterone in immature males of Oncorhynchus mykiss     

Denise Vizziano  Florence Le Gac  Alexis Fostier 《Fish physiology and biochemistry》1995,14(4):289-299

Three experimental approaches were chosen to study the question if the progestin 17-hydroxy-20-dihydroprogesterone (1720OHP) is synthesised in testes of young Oncorhynchus mykiss, in which the absence of spermatozoa was verified histologically: first, in order to detect 20-hydroxysteroid dehydrogenase activity (20HSD), testes homogenates were incubated with ³H-labeled 17OHP.Metabolites were analysed by TLC, HPLC, and repeated crystallization to constant isotope ratios. One of the metabolites was identified as 1720OHP-³H, indicating that already immature testes contain 20HSD activity and are able to produce 20-reduced steroids. Second, 1720OHP was quantified by radioimmunoassay in incubates of testes fragments. The sensitivity of the gonads to gonadotropin II (GtH II) became evident when comparing incubations in the absence and presence of GtH II. Third, plasma levels of 1720OHP were significantly higher in animals injected with partially purified salmon gonadotropin, compared to controls. Thus, for the first time, it could be shown that 20HSD is present in testicular cells other than spermatozoa. Furthermore, 1720OHP is indeed secreted at a very early stage of testicular development; 1720OHP secretion is also responsive to GtH II. Future studies will have to show if the functions of this progestin include the stimulation of spermatogenesis.  相似文献