MHC class I deficiency: susceptibility to natural killer (NK) cells and impaired NK activity.

The role of major histocompatibility complex (MHC) class I expression in natural killer (NK) cell target recognition is controversial. Normal T cell blasts from MHC class I-deficient mutant mice were found to serve as target cells for NK cells in vitro, which suggests that MHC class I molecules are directly involved in NK cell recognition. Spleen cells from the mutant mice were deficient in their ability to lyse MHC class I-deficient target cells or NK-susceptible tumor targets, and mutant mice could not reject allogeneic bone marrow. Thus, class I molecules may participate in the positive selection or tolerance induction of NK cells.     

Melanopsin-containing retinal ganglion cells: architecture, projections, and intrinsic photosensitivity

The primary circadian pacemaker, in the suprachiasmatic nucleus (SCN) of the mammalian brain, is photoentrained by light signals from the eyes through the retinohypothalamic tract. Retinal rod and cone cells are not required for photoentrainment. Recent evidence suggests that the entraining photoreceptors are retinal ganglion cells (RGCs) that project to the SCN. The visual pigment for this photoreceptor may be melanopsin, an opsin-like protein whose coding messenger RNA is found in a subset of mammalian RGCs. By cloning rat melanopsin and generating specific antibodies, we show that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs. In mice heterozygous for tau-lacZ targeted to the melanopsin gene locus, beta-galactosidase-positive RGC axons projected to the SCN and other brain nuclei involved in circadian photoentrainment or the pupillary light reflex. Rat RGCs that exhibited intrinsic photosensitivity invariably expressed melanopsin. Hence, melanopsin is most likely the visual pigment of phototransducing RGCs that set the circadian clock and initiate other non-image-forming visual functions.     

苦丁茶树种子育苗的研究

以９月份采收的苦丁茶树种子为材料，进行促后熟、发芽研究的结果表明：破壳、外源激素处理对发芽无促进作用；低温贮藏促进胚乳吸收．２％蔗糖溶液处理种子，能提早发芽３～４个月，但播种时，须将种子浅埋于细土中，否则将影响出苗率．     

网络经济背景下中国风险投资环境及对策分析

本文针对新的网络经济环境下我国风险投资所面临的环境现状、障碍及特点,分析了网络企业在银行贷款、风险投资等主要融资渠道中所存在的困难,并提出解决当前问题的主要对策。     

Epimeric separation of L-ascorbic acid and D-isoascorbic acid by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was used for separation of L-ascorbic acid (L-AA) and D-isoascorbic acid (D-IAA) in a model system. The effects of borate buffer concentration (0.05-0.25 M) and pH (pH 7.5-9.0) on migration time, resolution (Rs), and theoretical plates (N) were investigated. The migration times of L-AA and D-IAA increased with the increasing pH of carrier electrolyte (0.2 borate buffer), and the resolutions (Rs) of L-AA and D-IAA were calculated to be 12.98 at pH 9.0. Concentrations of borate buffer (pH 9.0) increased the Rs values of L-AA and D-IAA, and buffer concentrations >0.1 M were found to be effective for separation of L-AA and D-IAA. Methanol in the carrier electrolyte was also influential in improving the separation of L-AA and D-IAA, which increased with the increasing concentrations (0-10%) of methanol. The optimal separation conditions for L-AA and D-IAA were as follows: carrier electrolyte, 0.2 M borate buffer (pH 9.0); applied voltage, 25 kV, with an uncoated fused silica capillary, 75 microm (i.d.) x 57 cm.     

广西大麦生态区划初探

本文根据大麦生育期长短和灾害年份受害程度的不同,将广西大麦划分为四个生态区。分析了影响大麦发展的主要因素,桂南,桂中是大麦光温敏感期遇长期阴雨寡照天气;桂西是秋、冬、春三季干旱;桂北虽抽穗前后光温较宜,但收晒期雨水过多。同时提出各生态区发展大麦的关键技术措施。     

Purification and characterization of acetylcholinesterase from oriental fruit fly [Bactrocera dorsalis (Hendel)] (Diptera: Tephritidae)

An acetylcholinesterase (AChE, EC 3.1.1.7) was purified from the head of the insecticide susceptible oriental fruit fly, Bactrocera dorsalis (Hendel), by affinity chromatography of Triton X-100 extract. The degree of purification was about 8183-fold with recoveries of 52%. The molecular mass of purified AChE was 116 kDa for its native protein (nonreduced form) and 61 kDa for its subunits (reduced form) as revealed on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), suggesting that the homodimer of AChE linked with disulfide bonds. Nondenaturing PAGE of the purified AChE revealed only one molecular form. The maximum velocities (V(max)) for hydrolyzing acetylthiocholine (ATC), propionylthiocholine, and S-butyrylthiocholine were 833.3, 222.2, and 57.5 micromol/min/mg, and the Michaelis constants (K(m)) were 87.9, 26.9, and 195.3 microM, respectively. More than 97% of AChE activity was inhibited by 10 microM eserine or BW284C51, but only 53% of the activity was inhibited by ethopropazine at the same concentration. On the basis of the substrate and inhibitor specificities, the purified enzyme appeared to be a true AChE. Nevertheless, the purified AChE exhibited some distinctive characteristics including (i) a lack of the substrate inhibition phenomenon when using ATC as the hydrolyzing substrate and (ii) a higher V(m) value for ATC than AChE from other insect species. These biochemical properties may show that AChE purified from the oriental fruit fly may have structural differences from those of other insect species.     

Uncertainty analysis in near-surface soil moisture estimation on two typical land-use hillslopes

Purpose

Spatial prediction of near-surface soil moisture content (NSSMC) is necessary for both hydrologic modeling and land use planning. However, uncertainties associated with the prediction are always neglected and lack of quantitative analysis. The objective of this study was to investigate the influences of different sources of uncertainty on NSSMC estimation at two typical hillslopes (i.e., tea garden and forest).

Materials and methods

In this study, stepwise multiple regression models with terrain indices and soil texture were built to spatially estimate NSSMC on two typical land use hillslopes (tea garden and forest) at different dates. The uncertainties due to limited sample sizes used for developing regression models (uncertainty of model parameter), digital elevation model resolutions of 1, 2, 3, 4, and 5 m (uncertainty of terrain indices) and spatial interpolations of soil texture by kriging or cokriging with electromagnetic induction (uncertainty of soil texture), were investigated using bootstrap, resampling, and Latin hypercube sampling techniques, respectively.

Results and discussion

The accuracies of NSSMC predictions were acceptable for both tea garden (the Nash-Sutcliffe efficiency or NSE?=?0.34) and forest hillslopes (NSE?=?0.57). The model parameter uncertainty was more important on tea garden hillslope than on forest hillslope. A significant negative correlation (P?<?0.05) was observed between the model parameter uncertainty and the mean NSSMC of the hillslopes, indicating that the model parameter uncertainty was small when the hillslope was wet. The resolution uncertainty from digital elevation model had a minor effect on NSSMC predictions on both hillslopes. The texture uncertainty was weak on NSSMC estimations on tea garden hillslope. However, it was more important than the model parameter uncertainty on the forest hillslope.

Conclusions

Improving the regression model structure and the hillslope soil texture mapping are critical in the accurate spatial prediction of NSSMC on tea garden and forest hillslopes, respectively. This study presents techniques for analyzing three different uncertainties that can be used to identify the main sources of uncertainties in soil mapping.

     

Inhibitory effect of hot-water extract from dried fruit of Crataegus pinnatifida on low-density lipoprotein (LDL) oxidation in cell and cell-free systems

The dried fruit of Crataegus pinnatifida, a local soft drink material and medical herb, was found to possess potential against oxidative stress. In the preliminary study, the antioxidant potential of a hot-water extract obtained from the dried fruit of C. pinnatifida (CF-H) was evaluated in terms of its capacity of quenching 1,1-diphenyl-2-picrylhydrazyl free radicals (EC(50) = 0.118 mg/mL). After content analysis, it was found that CF-H is mainly composed of polyphenols including flavonoids (6.9%), procyanidins (2.2%), (+)-catechin (0.5%), and (-)-epicatechin (0.2%). The antioxidative bioactivity of CF-H had been assess previously using the models of CuSO(4) as cell-free system and sodium nitroprusside (SNP) plus macrophage RAW 264.7 cells as cell system to induce human low-density lipoprotein oxidation. CF-H was found to inhibit relative electrophoretic mobility and thiobarbituric acid reactive substances at the concentration of 0.5-1.0 mg/mL in the cell-free system and at 0.01-0.10 mg/mL in the cell system. Furthermore, it was found that CF-H decreased the SNP-induced cell lipid peroxidation and reduced glutathione depletion.