The Growth,physiological and biochemical response of foxtail millet to atrazine herbicide

Foxtail millet (Pennisetum glaucum L.) is a vital crop that is planted as food and fodder crop around the globe. There is only limited information is present for abiotic stresses on the physiological responses to atrazine. A field experiment was conducted to investigate the effects of different atrazine dosages on the growth, fluorescence and physiological parameters i.e., malonaldehyde (MDA) and reactive oxygen species (ROS) (H₂O₂ and O₂) in the leaves to know the extent of atrazine on oxidative damage of foxtail millet. Our experiment consisted of 0, 2.5, 12.5, 22.5 and 32.5 (mg/kg) of labeled atrazine doses on 2 foxtaill millet varieties. High doses of atrazine significantly enhanced ROS and MDA synthesis in the plant leaves. Enzymes activities like ascorbate peroxidase (APX) and peroxidase (POD) activities enhanced, while catalase (CAD) and superoxide dismutase (SOD) activities reduced with increasing atrazine concentrations. Finally atrazine doses at 32.5 mg/kg reduced chlorophyll contents, while chlorophyll (a/b) ratio also enhanced. Biomass, plant height, chlorophyll fluorescence parameters, minimal and maximal fluorescence (Fo, Fm), maximum and actual quantum yield, photochemical quenching coefficient, and electron transport rate are decreased with increasing atrazine doses.     

One-step hydrothermal preparation of chiral carbon quantum dots and enantioselective sensing of glutamine enantiomeric isomers

A novel method for chiral identification of glutamine enantiomers based on chiral carbon quantum dots (cCQDs) fluorescent probes. cCQDs were prepared using a one-step hydrothermal method with L-tryptophan as the carbon source and chiral source, producing spherical nanoparticles exhibiting a blue colour luminescence. The fluorescence intensity (F) of cCQDs was enhanced or quenched following the addition of chiral enantiomeric glutamine (L/D-Gln), and therefore cCQDs, as a fluorescence probe, could be used for enantioselective sensing of the L/D-Gln. The fluorescence enhancement value (∆F_E) exhibited good linearity with L-Gln concentration in the range 0.23–10.00 mM, and the limit of detection was 0.14 mM. The fluorescence quenching value (∆F_Q) showed a good linear relationship with D-Gln concentration in the range 0.29–10.00 mM, and the detection limit was 0.18 mM. The mechanism of fluorescence enhancement/quenching was explored by molecular modelling and the type of quenching. The method was applied to the determination of L-Gln content in real samples, and the recovery rate was satisfactory. This study provided a novel approach for the synthesis of cCQDs and the recognition of amino acid enantiomers.     

Improved photoluminescence stability and defect passivation in SbBr3 post-treated CsPbBr3 quantum dots under ambient conditions

Inorganic cesium lead halide perovskites have evoked wide popularity because of their excellent optoelectronic properties, high photoluminescence (PL) quantum yield (PLQY), and narrowband emission. Here, cesium lead bromide (CsPbBr₃) quantum dots (QDs) were synthesized via the ligand-assisted re-precipitation method. Post-synthesis treatment of CsPbBr₃ QDs using antimony tribromide improved the PL stability and optoelectronic properties of the QDs. In addition, the PLQY of the post-treated sample was enhanced to 91% via post-treatment, and the luminescence observed was maintained for 8 days. The post-synthesis treatment ensured defect passivation and improved the stability of CsPbBr₃ perovskite QDs. High-resolution transmission electron microscopy revealed the presence of more ordered, uniform-sized CsPbBr₃ QDs after post-synthesis treatment, and the uniformity of the sample improved as the day passed. The formation of a mixed crystal phase was observed from X-ray diffraction in both as-synthesized, as well as post-treated QDs samples with the possibility of a polycrystalline nature in the post-treated CsPbBr₃ QDs as per the selected area electron diffraction pattern. The X-ray photoelectron spectroscopy spectra confirmed the presence of antimony and the possibility of defect passivation in the post-treated samples. These QDs can act as potential candidates in various optoelectronic applications such as photodetectors and light-emitting diodes due to their high PLQY and longer lifetime.     

Density functional studies on herpes simplex virus type 1 thymidine kinase–substrate interactions: The role of Tyr-172 and Met-128 in thymine fixation

The enzyme herpes simplex virus type 1 thymidine kinase (HSV1 TK) salvages thymidine into the DNA metabolism of the virus. In the active site, the thymine ring of the nucleoside binds in a pocket, formed by two residues, Tyr-172 and Met-128, in a sandwich-type orientation. To investigate the nature of the thymine–enzyme pocket interactions, we have carried out density functional theory calculations with gradient-corrected exchange-correlation functionals of models of the thymine–HSV1 TK adduct. Our calculations indicate that the role of Met-128 in the substrate fixation is purely steric and hydrophobic, while the substrate–Tyr-172 interaction is essentially electrostatic in nature. These findings are completely consistent with the available catalytic properties of mutants on the 128 position. Proteins 31:453–459, 1998. © 1998 Wiley-Liss, Inc.     

Understandings and future challenges in soybean functional genomics and molecular breeding

Soybean(Glycine max) is a major source of plant protein and oil.Soybean breeding has benefited from advances in functional genomics.In particular,the release of soybean reference genomes has advanced our understanding of soybean adaptation to soil nutrient deficiencies,the molecular mechanism of symbiotic nitrogen(N) fixation,biotic and abiotic stress tolerance,and the roles of flowering time in regional adaptation,plant architecture,and seed yield and quality.Nevertheless,many challenges remain...     

黑水虻油的研究与综合利用

黑水虻Hermetia illucens L.是一种高脂肪昆虫,其体脂中不饱和脂肪酸与饱和脂肪酸的比例适宜,月桂酸等中链脂肪酸含量丰富,具有开发为饲用油、食用油及工业用油的广阔前景。本文从影响黑水虻油产量和质量的因素（黑水虻发育阶段、环境因子、养殖基质及制取工艺）、黑水虻油在饲料（畜禽和水产饲料）、食品（食用油）中的应用及其作为生物柴油和化妆品用油开发等方面,总结和归纳了国内外相关研究进展,为黑水虻油的深入开发与应用提供理论参考。     

GROWTH,DARK RESPIRATION AND PHOTOSYNTHETIC PARAMETERS OF THE COCCOLITHOPHORID EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) ACCLIMATED TO DIFFERENT DAY LENGTH-IRRADIANCE COMBINATIONS1

Growth, dark respiration rate, photosynthetic parameters, and chemical composition were determined for Emiliania huxleyi (Lohmann) Hay et Mohler acclimated to different combinations of day length (12, 18, 24 h) and irradiance (30, 100, 200, 800 μmol·m⁻²·s⁻¹). Specific growth rate (μ, day⁻¹) and carbon-specific dark respiration rate (r^C_d, day⁻¹) were independent of day length, but increased significantly with increasing irradiance. The photosynthetic parameters depended on the initial acclimation day length and irradiance: Chlorophyll a-specific maximum photosynthetic rate (P_m^B) increased up to threefold with decreasing day length and twofold with increasing irradiance. The maximum light utilization coefficient (α^B) and maximum quantum yield (φ_m) increased up to threefold with decreasing day length. α^B increased almost four-fold with decreasing irradiance, whereas φ_m was independent of irradiance. Literature data for phytoplankton indicate that P_m^B consistently increases with increasing irradiance, and day length-irradiance responses of α^B and φ_m are species specific. Results from the present experiment and other studies indicate that if day length-irradiance variability in the photosynthetic parameters are neglected, this may cause an over- or underestimation up to a factor of two in the photosynthetic rate estimation based on these parameters.     

调亏灌溉对菘蓝水分利用及产量的影响

通过探究水分调亏对河西地区膜下滴灌菘蓝(Isatis indigotica)各项生理指标、产量和水分利用的影响, 为菘蓝高效节水种植提供理论指导。于2016年在河西走廊中部张掖市民乐县益民灌溉试验站进行菘蓝水分调亏研究, 在保持苗期和肉质根成熟期充分灌溉的情况下, 在菘蓝营养生长期和肉质根生长期分别进行轻度、中度和重度的水分亏缺处理, 并测定各项光合生理指标、产量和水分利用率。结果表明, 营养生长期和肉质根生长期的中度与重度水分亏缺显著降低了菘蓝叶片净光合速率、叶面积指数、株高及主根长, 并且随水分亏缺程度加重降幅增大; 而轻度水分亏缺与对照组的差异不显著。营养生长期和肉质根生长期轻度水分亏缺处理的菘蓝产量与水分利用效率最高, 分别达到8 239.56 kg·hm^-2和24.11 kg·hm^-2·mm^-1; 其它水分亏缺处理组产量和水分利用效率均有所降低, 与对照组之间差异显著(P<0.05), 重度水分亏缺处理各项指标均最低。因此, 最优的菘蓝水分调控处理为营养生长期和肉质根生长期的轻度水分调亏, 能够降低菘蓝耗水量, 提高水分利用效率且其产量不会降低。     

氮肥对风箱果幼苗形态和生理特性的影响

采用盆栽实验的方法,设置4种水平氮肥处理,研究不同氮肥处理对风箱果1年生幼苗的生长表现、生物量积累和分配、光合生理特征、非结构性碳（NSC）积累等的影响。结果表明：施用氮肥促进了风箱果幼苗的地径、分枝数和冠幅的生长,促进了茎、叶和总生物量的积累（P<0.05）,提高了茎的生物量分配比例,减少了根生物量的分配比例;施用氮肥显著提高了净光合速率、叶氮含量、茎中的可溶性糖和NSC的积累（P<0.05）,但减少了根中的可溶性糖和NSC含量（P<0.05）。不同水平氮肥处理间（N1、N2、N3）的大部分指标差异并不显著,说明风箱果幼苗对土壤养分的变化并不敏感。