14C-寡糖在西瓜幼苗植株体内吸收传导和分布

应用同位素示踪技术研究了14C-寡糖在西瓜幼苗植株体内的吸收、传导和分布行为.自显影结果显示,寡糖通过处理叶部或根部后能够被西瓜幼苗植株快速吸收,在叶片中的传导表现为从叶缘向叶片中心分布的趋势.将叶部处理8h和根部处理24h后,14C-寡糖即可以传导和分布到西瓜幼苗的整个植株体内,证明14C-寡糖在西瓜幼苗植株体内具有较强的扩散和向基或向顶传导特征.结果表明,处理叶部4～120h时,根系、茎与未被直接处理的叶片等其它部位的放射性比活度分别由0.18×105和23.08×105Bq/kg变化为0.32×105和3.02×105Bq/kg,总体上表现出向基传导和分布的态势.处理根部4～120h时,西瓜幼苗植株根系、茎部、子叶和真叶中放射性比活度分别由22.23×105,2.23×105,8.33×105和12.78×105Bq/kg变化为431.11×105,42.23×105,65.57×105和78.89×105Bq/kg,表现出14C-寡糖在西瓜幼苗植株体内向顶传导作用和在地上部的积累态势很强.     

新型杀菌剂氟吗啉在黄瓜植株体内的吸收传导行为

利用生物测定技术和高效液相色谱法研究了氟吗啉在黄瓜植株体内的吸收、传导和分布行为及其机制. 结果表明, 氟吗啉能被黄瓜植株被动吸收, 并通过木质部在体内传导和分布.     

A Bioorthogonal Small‐Molecule‐Switch System for Controlling Protein Function in Live Cells

Chemically induced dimerization (CID) has proven to be a powerful tool for modulating protein interactions. However, the traditional dimerizer rapamycin has limitations in certain in vivo applications because of its slow reversibility and its affinity for endogenous proteins. Described herein is a bioorthogonal system for rapidly reversible CID. A novel dimerizer with synthetic ligand of FKBP′ (SLF′) linked to trimethoprim (TMP). The SLF′ moiety binds to the F36V mutant of FK506‐binding protein (FKBP) and the TMP moiety binds to E. coli dihydrofolate reductase (eDHFR). SLF′‐TMP‐induced heterodimerization of FKBP(F36V) and eDHFR with a dissociation constant of 0.12 μM . Addition of TMP alone was sufficient to rapidly disrupt this heterodimerization. Two examples are presented to demonstrate that this system is an invaluable tool, which can be widely used to rapidly and reversibly control protein function in vivo.     

DEVELOPMENT AND IDENTIFICATION OF CHINESE SPRING Ta1 kr ph1b PLANTS AND THEIR USE ON GENETIC TRANSFER OF DESIRABLE GENES FROM Aegilops

Chinese Spring Tal kr phlb plants were developed by hybridizing Tal common wheat and Chinese Spring phlb mutant and backcrosses. When Chinese Spring Tal kr phlb plants were crossed with some wild species of Triticeae, much more seeds of wide hybridization can be obtained without artificial emasculation and pollination because of the existence of Tat and kr genes. The homoeologous chromosomes between common wheat and the wild species of Triticeae can also pair and exhibit cross-over in the hybrid F1 plants because of the existence of the phlb gene. So that more alien desirable genes can be transferred to common wheat rapidly. Therefore, Chinese Spring Tal kr phlb plants become a powerful tool for wide hybridization and transferring alien desirable genes to common wheat.     

The fate of mercury species injected into coelomic fluid of starfish Leptasterias polaris

Mature starfish Leptasterias polaris, collected in the St Lawrence Estuary (eastern Canada), were exposed to two mercury species (HgCI₂ and CH₃HgCI) via injections into the coelomic fluid. In vivo effects of some complexing agents (glutathione, mercaptoethanol and EDTA) on the distribution of ²⁰³Hg-labelled species in starfish organs and tissues and their possible role in mercury transport through membranes were studied over a 24 h period. The excretion of ammonia and mercury was also measured. When injected alone, inorganic mercury and methylmercury [CH₃Hg(II)] were distributed in all organs, with a preferential adsorption in gonads, pyloric caeca and stomach. Mercury excretion was very low under all conditions studied. Mercaptoethanol, a small thiol ligand, was very efficient in reducing both mercury species in the coelomic fluid and seems to have promoted translocation towards most organs of the starfish. Its action is attributed to the formation of small and neutral complexes, HgL₂ and CH₃HgL, which can diffuse through membranes preserving their integrity. Glutathione increased the translocation of CH₃Hg(II) towards surrounding organs, but had no apparent effect on inorganic mercury. EDTA promoted the transport of inorganic mercury only. These results highlight (1) the particular interest of starfish to workers studying in vivo chemical complexation of mercury species, and (2) the potential role of complexing molecules in the biotransport of mercury species through living membranes.     

Effect of Interaction upon Translocation of Confined Polymer Chain Through Nanopore

运用二维的键长涨落模型和蒙特卡洛方法研究高分子链从一个受限空间到自由空间穿孔过程中,链单体与纳米孔之间的相互作用.结果表明,在不同的链长和纳米孔交互作用下,高分子链成功穿越自由能能垒取决于链长和纳米孔长度,并且由于交互作用降低了自由能能垒,导致高分子链在纳米管的平均捕获时间缩短.     

Uptake,Translocation, and Bioaccumulation of Elements in Forest Nettle (Laportea alatipes)

Elements found in the edible parts of plants are considered to be the main source of nutrients for humans and animals. However, there is insufficient information on the relationship between heavy metal pollution in the growing soil of most edible plants. In this study, the distribution of elements in the edible forest nettle (Laportea alatipes) was evaluated as a function of geographical location. Forest land soils had higher concentrations of minor elements (Cu, Cr, Ni, and Zn) compared to soils from rural and suburban areas. Translocation factors for Cd and Pb showed effective translocation from the roots to the leaves; however, these heavy metals in leaves were still above South African maximum permissible levels for vegetables. Atmospheric depositions may play a significant role in higher Cd and Pb concentrations in the leaves. Bioaccumulation factors showed the plant to accumulate Cu, Mn, and Zn to meet physiological requirement levels. Geoaccumulation indices and enrichment factors showed no soil contamination or minimal enrichment by trace metals. Principal component analysis showed Co, Cr, Cu, Fe, Ni, Pb, and Zn in soil to originate from a common source which may be soil silicates and other minerals.     

Applications of photocatalytic titanium dioxide-based nanomaterials in sustainable agriculture

Photocatalytic materials are attracting attention as emerging resources for agricultural applications. This timely review assesses the current developments in the use of biocompatible titanium dioxide (TiO₂)-based photocatalytic nanomaterials (TiO₂-PN) as models to unravel agricultural growth, harvest, and post-harvest problems. Such developments can lead to technological innovations aimed at addressing the pressing global environmental challenges faced by farming. TiO₂-PN have been used as antimicrobial, growth-regulating, and fertilizer-like agents. The promising agricultural research applications of TiO₂-PN are highlighted along with a discussion of the main challenges that will need to be overcome to fully understand the roles of TiO₂-PN in the sustainable and productive exploitation of land and water for agricultural applications under natural conditions. In particular, rhizosphere internalization, translocation, and plant bioaccumulation pathways of photocatalytic materials from environmental exposition are outlined to illustrate the effect of TiO₂ on the agricultural cycle. Nanotoxicology and regulations are also discussed to illustrate the importance of biocompatibility and green synthesis of nanomaterials for safe use in real applications. This overview is focused on motivating and intensifying our understanding of on-site agricultural studies. Complementary biological approaches and structural damage observed by biological transmission electron, scanning electron, and optical microscopies should accelerate the practical contribution of TiO₂-PN to sustainable agriculture in conjunction with plant factories and plasma nitrogen fixation technology. Loadings below 10 μg/L of TiO₂-PN with a size of 40 nm benefit seed germination and root elongation as well as partially suppressing metal root translocation. However, only approximately 5% of current studies were carried out in real agricultural settings.     

Coupling Effects of Electrostatic Interactions and Salt Concentration Gradient in Polymer Translocation through a Nanopore: A Coarse-Grained Molecular Dynamics Simulations Study

We study the influence of polymer pore interactions and focus on the role played by the concentration gradient of salt in the translocation of polyelectrolytes (PE) through nanopores explicitly using coarse-grained Langevin dynamics simulations. The mean translocation time is calculated by varying the applied voltage, the pH, and the salt concentration gradient. Changing the pH can alter the electrostatic interaction between the protein pore and the polyelectrolyte chain. The polymer pore interaction is weakened by the increase in the strength of the externally applied electric field that drives translocation. Additionally, the screening effect of the salt can reduce the strong charge-charge repulsion between the PE beads which can make translocation faster. The simulation results show there can be antagonistic or synergistic coupling between the salt concentration-induced screening effect and the drift force originating from the salt concentration gradient thereby affecting the translocation time. Our simulation results are explained qualitatively with free energy calculations.     

Design, synthesis, and delivery properties of novel guanidine-containing molecular transporters built on dimeric inositol scaffolds

We have developed a novel class of synthetic molecular transporters that contain eight residues of guanidine with an inositol dimer as the scaffold. The dimers were prepared by connecting two units of myo- or scyllo-inositol via a carbonate or amide linkage, and the multiple units of the guanidine functionality were constructed on the inositol scaffold by means of peracylation with omega-aminocarboxylate derivatives of varying length. Bioassays based on confocal laser scanning microscopy and fluorescence-activated cell sorter analyses indicated that these transporters display a varying degree of membrane translocating ability, and the intracellular localization and mouse-tissue distribution studies strongly suggested that these transporters undergo substantially different mechanistic processes from those of peptide transporters reported to date. It was also shown that doxorubicin, an anticancer antibiotic, can be efficiently delivered into mouse brain by aid of this type of transporter.