Intracellular interference of tick-borne flavivirus infection by using a single-chain antibody fragment delivered by recombinant Sindbis virus.

A single-chain antibody fragment that identifies a neutralizing epitope on the envelope protein of louping ill and some other tick-borne flaviviruses was previously expressed in soluble form from bacteria and shown to be functionally active in vitro. To see whether or not the single-chain antibody could bind and inactivate infectious virus in vivo, we have used recombinant Sindbis virus as a delivery vehicle for intracellular expression of the antibody fragment. The variable genes and interchain linker encoding the single-chain antibody were cloned into a double subgenomic Sindbis virus expression vector to generate recombinant Sindbis virus. Infection with this recombinant Sindbis virus provided high-level cytoplasmic expression of the antibody fragment in mammalian cells. We demonstrate (i) that the antibody fragment was antigen binding and (ii) that louping ill virus infectivity was significantly reduced in the presence of intracellular antibody expressed by the superinfecting recombinant Sindbis virus.     

Ras transformation results in an elevated level of cyclin D1 and acceleration of G1 progression in NIH 3T3 cells.

Ectopic overexpression of v-H-Ras protein in NIH 3T3 cells resulted in cellular transformation and an acceleration of G1 progression of these cells. A shortened G1 phase was found to be associated with an increased level of cyclin D1 but not cyclin E protein. Using an antisense blocking method, reduced synthesis of cyclin D1 in v-H-Ras transformants resulted in a slower G1 progression rate of these cells. Although constitutive overexpression of cyclin D1 in NIH 3T3 cells accelerated G1 progression, cells remained untransformed. Furthermore, inhibition of cyclin D1 synthesis greatly impaired the soft-agar cloning efficiency of v-H-Ras transformants. These results suggest that increased expression of cyclin D1 is necessary but not sufficient for the transforming activity of v-H-Ras. Similar effect on cell cycle progression was also observed in Raf-transformed cells. In addition to cyclin D1, cyclin E protein was found to be elevated in Src transformants. This may account for the further shortening of the G1 phase of these cells. Activation of an additional Ras-independent pathway was suggested to be responsible for the further acceleration of the G1 phase in Src transformants.     

Characterization of electron transfer reactions of microperoxidase assembled at short-chain thiol-monolayers on gold

In this study thiol-monolayers were used in order to modify gold and provide suitable chemical functionalities for the immobilization of the small redox-active haem-containing peptide, microperoxidase (MP-11). Initially, we assembled a variety of thiol-containing species on the gold electrodes and measured a series of electron transfer reactions, each characteristic of the surface-modifier. Using suitable immobilization strategies, we subsequently covalently bound MP-11 to appropriate monolayers and found two characteristic electrochemical responses (i.e. using MP-11 bound to mercaptopropionic acid, redox peaks were seen at E^0′ = −315 mV and at +179 mV versus Ag|AgCl, with the former being attributed to the haem and the latter with the thiol monolayer). Exposure of the peptide-thiol surface to UV irradiation resulted in cleavage of the Au---S bond, leading to a decrease in the magnitude of both responses. Our work is supported by corroborative evidence showing the immobilization of the peptide, obtained using both X-ray photoelectron and reflectance Fourier transform infra-red spectroscopies. We hypothesize that differences in the ionic charges on the protein backbone account for the shift in E^0′ for MP-11, as observed in our system, when compared to that found for MP-11 immobilized by different strategies.     

The maize actin-depolymerizing factor, ZmADF3, redistributes to the growing tip of elongating root hairs and can be induced to translocate into the nucleus with actin

The maize actin depolymerizing factor, ZmADF3, binds G-and F-actin, and increases in vitro actin dynamics. Polyclonal antibodies have been raised against ZmADF3 and these detect a single band of approximately 17 kDa in all maize tissues examined, with the exception of pollen. In the development of root hairs, the distribution of ZmADF3 is related to actin reorganization. In the early stages of hair development, ZmADF3 is distributed throughout the cytoplasm. As the hair emerges and the microfilament bundles redirect to the outgrowth there is a simultaneous redistribution of ZmADF3 which now concentrates at the tip of the emerging hair and remains in this position as elongation proceeds. These observations show that ZmADF3 localizes to a region where actin is being remodelled during tip growth. After cytochalasin D treatment which disrupts actin filaments, short rods of ZmADF3 and actin appear in the nucleus suggesting that ZmADF3 may function by guiding actin to sites of actin polymerization.     

广西和湖南的大瓣鱼科化石

详细记述了广西博白和湖南长沙中泥盆世的大瓣鱼科化石,依其特征建立一新属——广西瓣甲鱼Guangxipetalichthysgennov,该属头甲骨片排列型式与澳大利亚的Shearsbyaspis较为接近。同时讨论了鱼化石动物群及相关的地层问题。     

Chemosensory and photosensory perception in purple photosynthetic bacteria utilize common signal transduction components.

The chemotaxis gene cluster from the photosynthetic bacterium Rhodospirillum centenum contains five open reading frames (ORFs) that have significant sequence homology to chemotaxis genes from other bacteria. To elucidate the functions of each ORF, we have made various mutations in the gene cluster and analyzed their phenotypic defects. Deletion of the entire che operon (delta che), as well as nonpolar disruptions of cheAY, cheW, and cheR, resulted in a smooth-swimming phenotype, whereas disruption of cheB resulted in a locked tumbly phenotype. Each of these mutants was defective in chemotactic response. Interestingly, disruption of cheY resulted in a slight increase in the frequency of tumbling/reversal with no obvious defects in chemotactic response. In contrast to observations with Escherichia coli and several other bacteria, we found that all of the che mutant cells were capable of differentiating into hyperflagellated swarmer cells when plated on a solid agar surface. When viewed microscopically, the smooth-swimming che mutants exhibited active surface motility but were unable to respond to a step-down in light intensity. Both positive and negative phototactic responses were abolished in all che mutants, including the cheY mutant. These results indicate that eubacterial photosensory perception is mediated by light-generated signals that are transmitted through the chemotaxis signal transduction cascade.     

褐稻虱在武育粳2号上不同生育期危害对水稻产量结构的影响

通过试验测定在武育粳2号上水稻拔节期正处于幼穗形成阶段,受褐稻虱危害实粒数减少,产量下降;孕穗期较耐褐稻虱危害,有明显的补偿作用;孕穗末期至灌浆初期为水稻受害最敏感的时期,危害后使结实率和千粒重均明显下降,水稻显著减产;灌浆后期至乳熟期受褐稻虱危害主要导致干粒重降低,且越接近成熟产量损失越低。     

Physiologic regulation of mixtalol in rape senescence and its yield effects

Physiologic and yield effects of mixtalol at various concentrations sprayed on rape at the anthesis stage were examined. Foliar sprays of 4 and 2 ppm mixtalol significantly increased the chlorophyll content of rape leaves and pods, reduced the accumulation of malondialdehyde and ethylene production, and delayed the degradation of superoxide dismutase and catalase activities of the rape plant. Mixtalol also increased root oxidizability. Meanwhile, the number of branches and pods per plant was increased, and a 10.7% and 8.2% increase of seed yield over the controls was observed with treatments of 4 and 2 ppm mixtalol, respectively. No significant effects from mixtalol were observed on the maturation of plants or on the seed oil content or the erucic acid and glucosinolate content. Total rape oil production increased with 4 and 2 ppm mixtalol significantly by 12.4% and 10.5%, respectively, over the controls.Abbreviations MTL mixtalol - MDA malondialdehyde - TBA thiobarbituric acid - SOD Superoxide dismutase - CAT catalase - TTC tetrazolium     

Differential modulation of carbachol and trans-ACPD-stimulated phosphoinositide turnover following traumatic brain injury

In the fluid percussion model of traumatic brain injury (TBI), we examined muscarinic and metabotropic glutamate receptor-stimulated polyphosphoinositide (PPI) turnover in rat hippocampus. Moderate injury was obtained by displacement and deformation of the brain within the closed cranial cavity using a fluid percussion device. Carbachol and (±)-1-Aminocyclopentane-trans-1,3.-dicarboxylic acid (trans-ACPD)-stimulated PPI hydrolysis was assayed in hippocampus from injured and sham-injured controls at both 1 hour and 15 days following injury. At 1 hour after TBI, the response to carbachol was enhanced in injured rats by up to 200% but the response to trans-ACPD was diminished by as much as 28%. By contrast, at 15 days after TBI, the response to carbachol was enhanced by 25% and the response to trans-ACPD was enhanced by 73%. The ionotropic glutamate agonists N-methyl-D-aspartate (NMDA), and -amino-3 hydroxy-5-methyl-4-isoxazolepropionate (AMPA), did not increase PPI hydrolysis in either sham or injured rats and injury did not alter basal hydrolysis. Thus, hippocampal muscarinic and metabotropic receptors linked to phospholipase C are differentially altered by TBI.Abbreviations used TBI traumatic brain injury - EAA excitatory amino acids - PPI polyphosphoinositides - IP inositol phosphates - NMDA N-methyl-D-aspartate - AMPA -amino-3-hydroxy-5-methylisoxazole-4-propionate - trans-ACPD (±)-1-Aminocyclopentanetrans-1,3-dicarboxylic acid - LTP long term potentiation