黄土高原地区提取植被信息方法的研究

研究评价了适于黄土高原地区植被信息提取的最佳植被指数和方法。该地区分布有落叶阔叶林、草原和荒漠,植被类型丰富多样。然而土壤背景对植被信息提取有较大影响。经对比分析,修正后的土壤调节植被指数（ＭＳＡＶＩ）, 不仅能增强植被信号,并能大大减小土壤背景的影响,同时又能宏观地反映该地区植被类型的分布状况。它是黄土高原地区目前提取植被信息较好的植被指数。标准化差值植被指数（ＮＤＶＩ）、土壤调节植被指数（ＳＡＶＩ）和垂直植被指数（ＰＶＩ）分别适用于高密度、中等密度和稀少植被地区植被信息的提取和监测。各种植被指数多时象累加产生的图像能较好地提取植被信息     

Substance P and neurokinin A metabolism by cultured human skeletal muscle myocytes and fibroblasts

A recent study determined that cultured human skeletal muscle adult myoblasts, myotubes, and fibroblasts degraded angiotensins and kinins via neutral endopeptidase-24.11 (NEP-24.11; EC 3.4.24.11) and aminopeptidase N (APN; EC 3.4.11.2). Due to the possible importance of other peptides to skeletal muscle blood flow and function, the present study looked specifically at the metabolism of the neurokinins substance P (SP) and neurokinin A (NKA) by skeletal muscle peptidases. The results show that SP is degraded not only by NEP-24.11, but also sequentially by dipeptidyl(amino)peptidase IV (DAP IV; EC 3.4.14.5)/APN. NKA is unaffected by DAP IV but is metabolized by NEP-24.11 and APN. NEP-24.11 was inhibited by phosphoramidon (IC₅₀ = 80 nM), thiorphan and ZINCOV, DAP IV by diprotin A (IC₅₀ = 8 μM), and APN by amastatin (IC₅₀ = 50 nM) and bestatin (IC₅₀ = 100 μM). Skeletal muscle myocyte and fibroblast metabolism of SP and NKA may regulate local skeletal muscle vascular and extravascular functions including SP- and NKA-mediated nerve-induced vasodilation. Inhibition of both NEP-24.11 and DAP IV/APN may increase skeletal muscle blood flow and decrease peripheral vascular resistance via potentiation of local neurokinin levels.     

A flash-photolysis study of the reactions of acaa 3-ttype cytochrome oxidase with dioxygen and carbon monoxide

The time course of absorbance changes following flash photolysis of the fully-reduced carboxycytochrome oxidase fromBacillus PS3 in the presence of O₂ has been followed at 445, 550, 605, and 830 nm, and the results have been compared with the corresponding changes in bovine cytochrome oxidase. The PS3 enzyme has a covalently bound cytochromec subunit and the fully-reduced species therefore accommodates five electrons instead of four as in the bovine enzyme. In the bovine enzyme, following CO dissociation, four phases were observed with time constants of about 10 s, 30 s, 100 s, and 1 ms at 445 nm. The initial, 10-s absorbance change at 445 nm is similar in the two enzymes. The subsequent phases involving hemea and Cu_A are not seen in the PS3 enzyme at 445 nm, because these redox centers are re-reduced by the covalently bound cytochromec, as indicated by absorbance changes at 550 nm. A reaction scheme consistent with the experimental observations is presented. In addition, internal electron-transfer reactions in the absence of O₂ were studied following flash-induced CO dissociation from the mixed-valence enzyme. Comparisons of the CO recombination rates in the mixed-valence and fully-reduced oxidases indicate that more electrons were transferred from hemea ₃ toa in PS3 oxidase compared to the bovine enzyme.     

Fate of elemental sulfur in an intertidal sediment

Abstract: Sediment from a tidal flat at Wedderwarden, near the mouth of the Weser estuary, northern Germany, was amended with elemental sulfur, and concentrations of metabolic end products were monitored. The production of both sulfate and sulfide was consistent with disproportionation as the most important fate of the added elemental sulfur. A population of bacteria conducting active elemental sulfur disproportionation was also enriched from the sediment. In the enrichments, containing both elemental sulfur and Fe oxides as a sulfide 'scrub', sulfide and sulfate were produced in a ratio of     , somewhat lower than the predicted ratio of     . The mismatch between predicted and observed production ratios is explained by the channelling of electrons into autotrophic or mixotrophic CO₂ fixation rather than sulfide formation. The production of organic carbon, in the correct amount to explain the observed sulfide to sulfate production ratio, was verified by organic carbon analysis. Finally, rates of sulfate reduction were identical in the elemental sulfur amended sediment, and in control sediment with no added sulfur. Hence, the heterotrophic bacterial community was completely unaffected by an active metabolism conducting elemental sulfur disproportionation.     

中国沿海代表性河口地区鳗苗群体形态特征的比较研究

本文报道了１９９２—１９９４年连续３年采自海南至辽宁（包括台湾）沿海７个代表性河口地区鳗苗群体的主要形态特征比较研究结果。４项计数性状和３项度量性状,差异系数分析结果未达到亚种差异水平;判别函数显示,大多数群体间存在显著差异,这种差异应源于遗传变异。各年差异变化无规律,可能与鳗苗漂游分布的随机性有关。     

中国脊翅叶蝉属种类记述（同翅目：叶蝉科）

本文记述４种中国脊翅叶蝉,其中包括１新种──杨氏脊翅叶蝉Ｐａｒａｂｏｌｏｐｏｎａｙａｎｇｉｓｐ．ｎ．,并报道了其中２个已知种的新分布地。文中还列有分种检索表。新种模式标本存西北农业大学昆虫博物馆。     

用人工合成的丁型肝炎病毒抗原多肽检测丁肝病毒IgM抗体及其初步应用

用人工合成的丁型肝炎病毒抗原（ＨＤＶ－Ａｇ）肽建立了检测抗ＨＤＶ－ＩｇＭ抗体的ＥＬＩＳＡ方法,本法操作简便、快速,重复性好,特异性强,与抗ＨＡＶ－ＩｇＭ、抗Ｈｋ－ＩｇＭ、抗ＨＢｓ－ＩｇＭ、抗ＨＣＶ－ＩｇＩ、抗ＣＭＶ－ＩｇＭ、抗ＲＶ－ＩｇＭ、类风湿因子（ＲＦ）及抗核抗体（ＡＮＡ）阳性血清均不起反应,且可被２－巯基乙醇阻断而不起反应。经初步临床应用,３１例正常人血清抗ＨＤＶ－ＩｇＭ全部阴性,２８例慢活肝患者检出率为３２．１％（９／２８）,１７例慢迁肝患者血清阳性率为１１．８％（２／１７）１８例肝癌和肝硬化病人血清阳性率为２２．２％（４／１８）这三组病人与正常对照者相比较均有显著性差异（Ｐ＜０．００１）。此外,抗ＨＤＶ－ＩｇＭ阳性血清的ＡＬＴ值均明显高于正常参考范围,提示在ＨＤＶ感染过程中,患者肝细胞进一步受损。实验结果证明,抗ＨＤＶ－ＩｇＭ是诊断ＨＤＶ感染的重要指标,对ＨＤＶ感染早期诊断具有重要价值。     

Immunochemical and immunohistological expression of Lewis histo-blood group antigens in small intestine including individuals of the Le(a+b+) and Le(a−b−) nonsecretor phenotypes

Histological samples and total non-acid glycosphingolipids were prepared from small intestine of human cadavers with the Le(a+b+) and Le(a–b–) nonsecretor phenotypes and contrasted with the more common Lewis phenotypes. Glycolipid fractions were analysed by thin-layer chromatography and tested for Lewis activity with monoclonal antibodies reactive to Lewis epitopes. Paraffin-embedded small intestine sections were also fluorescently immunostained with anti-Lewis antibodies. Unlike the common Lewis positive phenotypes, we were immunochemically able to demonstrate the copresence of large amounts of Le^a and Le^b glycolipids in the Le(a+b+) sample. In addition we demonstrated increased formation of extended Lewis structures in this phenotype. By immunohistochemistry Le^a, Le^b and type 1 precursor chain epitopes could be demonstrated in the brush border. These results show that the expression of the Le(a+b+) phenotype at the erythrocyte phenotyping level parallels the small intestinal expression of this phenotype, and the patterns of Lewis antigen expressions are unique to this phenotype. By immunohistochemistry and immunochemistry we also demonstrated the presence of trace amounts of Lewis active glycoconjugates in the small intestine of the Le(a–b–) nonsecretor and Le(a+b–) samples. In the Le(a–b–) nonsecretor Le^a and Le^b activity was absent and type 1 precursor was present in brush border, while Le^b activity was immunohistologically demonstrated in the Golgi apparatus of the deep glands. Trace amounts of both Le^a and Le^b glycolipids were identified in this sample. In parallel trace Le^b activity could also be detected in the glycolipids of the Le(a+b–) sample and could be immunohistologically demonstrated to be fully expressed in occasional cells in the deep glands of the small intestine, a pattern quite dissimilar to that of the Le(a–b–) nonsecretor. The results in this paper show that the expression of Lewis glycoconjugates in the small intestine parallel the expression of Lewis erythrocyte phenotypes. However, inappropriate Lewis activity is also seen in individuals of other phenotypes and the mechanisms by which these Lewis antigens are made appears to be different for different phenotypes.Abbreviations FITC fluorescein isothiocyanate - HPLC high-performance liquid chromatography - NeuAc N-acetyl-d-neuraminic acid - RBC red blood cell - TLC thin-layer chromatography - TRITC tetramethyl rhodamine isothiocyanate