Oxygen concentration, nitrogenase activity and heterocyst frequency in the leaf cavities of Azolla filiculoides Lam

Following exposure to UV light the synthesis of six polypeptides (112, 100, 89, 76, 71 and 65 kDa) was found to be enhanced or induced in the alga Chlamydomonas reinhardtii. Treatment with 4-nitroquinoline-N-oxide (NQO) resulted in the enhanced/induced synthesis of six polypeptides with molecular masses similar to those enhanced following exposure to UV light. Heat shock resulted in the enhanced synthesis of five polypeptides (89, 76, 71, 60 and 22 kDa), three of which (89, 76 and 71 kDa) had apparently identical mobilities to polypeptides whose synthesis was enhanced following UV treatment.     

Effects of ELF (1-120 Hz) and modulated (50 Hz) RF fields on the efflux of calcium ions from brain tissue in vitro

We have previously shown that 16-Hz, sinusoidal electromagnetic fields can cause enhanced efflux of calcium ions from chick brain tissue, in vitro, in two intensity regions centered on 6 and 40 Vp-p/m. Alternatively, 1-Hz and 30-Hz fields at 40 Vp-p/m did not cause enhanced efflux. We now demonstrate that although there is no enhanced efflux associated with a 42-Hz field at 30, 40, 50, or 60 Vp-p/m, a 45-Hz field causes enhanced efflux in an intensity range around 40 Vp-p/m that is essentially identical to the response observed for 16-Hz fields. Fields at 50 Hz induce enhanced efflux in a narrower intensity region between 45 and 50 Vp-p/m, while radiofrequency carrier waves, amplitude modulated at 50 Hz, also display enhanced efflux over a narrow power density range. Electromagnetic fields at 60 Hz cause enhanced efflux only at 35 and 40 Vp-p/m, intensities slightly lower than those that are effective at 50 Hz. Finally, exposures over a series of frequencies at 42.5 Vp-p/m reveal two frequency regions that elicit enhanced efflux--one centered on 15 Hz, the other extending from 45 to 105 Hz.     

Variation of the enhanced biologically damaging solar UV due to clouds.

The variation of the biologically damaging solar UV (UVBE) enhanced by clouds above that of clear sky UVBE has been investigated. This was undertaken for summer through to winter for SZA of 5 to 60 degrees employing an integrated automatic cloud and spectral UV measurement system that recorded the solar UV spectra and the sky images at five minute intervals. The UVBE calculated with action spectra with higher relative effectiveness in the UVA produced the lower percentage of cloud enhanced cases. The DNA UVBE provided the highest percentage of cloud enhanced cases compared to the total number of UV scans with 2.2% cloud enhanced cases. As a comparison, the plant and fish melanoma UVBE provided the lowest percentage of cloud enhanced cases with 0.6 to 0.8% cloud enhanced cases. For the cases of cloud enhanced UVBE, the average ratio of the measured UVBE to calculated cloud free UVBE for the photokeratitis, cataracts, plant, generalized plant damage and fish melanoma action spectra was 1.21 to 1.25. In comparison, the highest value of 1.4 was for the DNA action spectrum.     

螺旋CT增强扫描对孤立性肺结节的诊断价值

目的:研究螺旋CT增强扫描时孤立性肺结节的诊断价值。方法:回顾分析经病理证实的恶性结节50例、炎性结节26例、结核瘤12例的螺旋CT增强扫描的表现。结果:恶性结节和炎性结节增强扫描的强化程度明显高于结核瘤(P＜0．05)。炎性结节强化峰值的时间较恶性结节延迟。恶性结节增强扫描出现点、条状及边缘强化。结论:螺旋CT增强扫描对孤立性肺结节的诊断具有重要临床应用价值。     

增强UV-B辐射和氮素互作对植物生长代谢影响的研究进展

不同氮源条件下,UV-B辐射增强能改变植株对氮的吸收利用以及植株叶片的碳氢比和碳氮比,增加氨基酸的生物合成.缺氮条件下, UV-B辐射增强使植物叶片中SOD、POD活性增强,MDA含量增加;氮素过量时,UV-B辐射增强会降低植物对UV-B辐射的耐性.UV-B辐射增强和氮缺乏相互作用会降低叶片的光合速率、叶绿素含量、可溶性糖及淀粉含量,从而抑制植物的生长,降低生物量.该文对近年来国内外有关UV-B辐射增强与氮素相互作用对植物抗氧化系统、氮代谢、光合作用、生物量和形态结构的影响进行综述.     

A novel function of VEGF receptor-2 (KDR): rapid release of nitric oxide in response to VEGF-A stimulation in endothelial cells

Effect of six steroidal saponins isolated from Anemarrhenae rhizoma on superoxide generation in human neutrophils was investigated. The steroidal saponins examined were anemarrhenasaponin-I (An-I), anemarrhenasaponin-Ia (An-Ia), timosaponin B-I (TB-I), timosaponin B-II (TB-II), timosaponin B-III (TB-III) and timosaponin A-III (TA-III). An-I, An-Ia, and TB-III suppressed the superoxide generations induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) and arachidonic acid (AA) in a concentration-dependent manner, but enhanced that induced by phorbol 12-myristate 13-acetate (PMA). While TB-II also suppressed and enhanced the superoxide generations induced by fMLP and PMA, respectively, the compound significantly enhanced the AA-induced superoxide generation. TB-I enhanced the fMLP-induced superoxide generation in a low concentration range (peak at 40 microM), gave no effect on the PMA-induced superoxide generation and weakly enhanced the AA-induced superoxide generation. TA-III enhanced the fMLP-induced superoxide generation more than twice as much as that by TB-I in the same concentration range. However, TA-III enhanced the PMA-induced superoxide generation and most significantly suppressed the AA-induced superoxide generation.     

Mutations in wheat exhibiting growth-stage-specific resistance to biotrophic fungal pathogens

Two mutants were isolated in wheat that showed enhanced resistance towards Puccinia striiformis f. sp. tritici, the fungal causal agent of yellow rust. The altered phenotype of I3-48 is due to a minimum of two mutation events, each showing a partial, additive effect, with one mutation segregating with a deletion on the long arm of chromosome 4D. In the case of I3-54, the enhanced resistance is due to a single, dominant mutation. In both mutants, the expression of the enhanced resistance is growth-stage specific. With I3-54, the full resistance phenotype is apparent from the third seedling leaf onwards, while with I3-48, a full resistance phenotype is only seen on the tenth and subsequent leaves. In addition to the enhanced resistance towards yellow rust, I3-48 also shows enhanced resistance towards brown rust, and I3-54 shows enhanced resistance to powdery mildew.     

Responses in growth,physiology and nitrogen nutrition of dragon spruce (<Emphasis Type="Italic">Picea asperata</Emphasis>) seedlings of different ages to enhanced ultraviolet-B

In the southeast of the Qinghai–Tibetan Plateau of China, dragon spruce (Picea asperata) is a key species and widely used in reforestation processes in the area. The paper mainly studied the effects of ultraviolet-B (UV-B) on growth, physiology and nitrogen nutrition of 3- and 6-year-old dragon spruce seedlings. The experimental design included ambient UV-B (control) and enhanced UV-B (+UV-B, a 30% increase). Enhanced UV-B significantly decreased growth, needle and root nitrogen concentration, needle nitrate reductase activity and increased UV-B absorbing compounds and malondialdehyde (MDA) content of two old dragon spruce seedlings. Glutamine synthetase activity was not affected by enhanced UV-B in two old dragon spruce seedlings. On the other hand, different old seedlings also exhibited different physiological responses to enhanced UV-B radiation. Chlorophyll content, carotenoids content and soluble protein content in 3-year-old seedlings significantly reduced by enhanced UV-B, but those in 6-year-old seedlings were not affected by enhanced UV-B. Proline content of 6-year-old seedlings were increased by enhanced UV-B. Compared with the 3-year-old seedlings, the 6-year-old seedlings showed lower reduction of growth and MDA content, and accumulated more proline and UV-B absorbing compounds for protecting seedlings under enhanced UV-B. The results implicated that 3-year-old seedlings were more sensitivity to enhanced UV-B than 6-year-old seedlings.     

Simultaneous detection of bacteria expressing GFP and DsRed genes with a flow cytometer

BACKGROUND: In this study, Escherichia coli cells producing red fluorescent protein of Discosoma sp. (drFP583 DsRed) were investigated with flow cytometry by using 488 nm excitation. We also studied whether green fluorescent protein (GFP) and drFP583 could be detected simultaneously from a single bacterial cell. METHODS: Plasmids pDsRed and pEGFP were used for the production of drFP583 and enhanced GFP, respectively, in E. coli MC1061 cells. To produce enhanced GFP and drFP583 simultaneously, plasmids pG9R and pG19R were constructed. These encode tandem fusions of enhanced GFP and drFP583 to ensure similar production levels for both proteins. RESULTS: Bacteria producing enhanced GFP and drFP583 were found to be brightly green and red fluorescent, respectively. Production of enhanced GFP and drFP583 fusion proteins resulted in bacteria that emitted both green and red fluorescence, which was detected easily by a flow cytometer using single laser excitation. Previously reported tetramerization of drFP583 did not restrict its use as a reporter gene, although it maturated significantly slower than enhanced GFP. CONCLUSIONS: The results show that enhanced GFP and drFP583 proteins can be detected simultaneously from single bacteria with a standard flow cytometer with simple optical configuration.     

增强UV-B辐射对麻花艽叶片的抗氧化酶的影响

以青藏高原的特有植物麻花艽为材料,研究麻花艽叶片抗氧化酶系统对增强UV-B辐射的响应。结果表明：在UV-B处理初期,麻花艽叶片SOD、POD的酶活性都能增加,但随着处理时间的延长,SOD、POD的活性呈现下降趋势。麻花艽叶片CAT的酶活性在UVB处理后下降明显,但作为清除叶绿体中H2O2的关键酶AP的酶活性表现为明显地增加趋势,说明在对麻花艽叶片增强UV-B辐射反应中AP起有着重要作用。MDA的含量随UV-B处理时间延长而增加,表明UV-B降低了细胞内活性氧自由基的清除能力,膜脂过氧化作用加剧,导致了对麻花艽叶片的伤害效应。     

Bioengineered nisin derivatives with enhanced activity in complex matrices

Nisin A is the best known and most extensively characterized lantibiotic. As it is ribosomally synthesized, bioengineering‐based strategies can be used to generate variants. We have previously demonstrated that bioengineering of the hinge region of nisin A can result in the generation of variants with enhanced anti‐microbial activity against Gram‐positive pathogens. Here we created a larger bank of hinge variant producers and screened for producers that exhibit enhanced bioactivity as assessed by agar‐based assays against a selection of target strains. Further analysis of 12 ‘lead’ variants reveals that in many cases enhanced bioactivity is not attributable to enhanced specific activity but is instead as a consequence of an enhanced ability to diffuse through complex polymers. In the case of two variants, which contain the residues SVA and NAK, respectively, within the hinge region, we demonstrate that this enhanced trait enables the peptides to dramatically outperform nisin A with respect to controlling Listeria monocytogenes in commercially produced chocolate milk that contains carrageenan as a stabilizer.     

The adhesion of protein A-bearing Staphylococcus aureus organisms to soluble-staphylococcal-antigens-coated HeLa cells mediated by specific antibodies

The adhesion of staphylococcal protein A (SpA)-bearing Staphylococcus aureus Cowan I organisms to HeLa cells was enhanced by pretreatment of HeLa cells with staphylococcal extracellular antigens and antibodies to them. The adhesion of HLj, an SpA-poor mutant derived from Cowan I, to HeLa cells was not enhanced by the same pretreatment of HeLa cells. Furthermore, the enhanced staphylococcal adhesion was inhibited by soluble SpA. The antigen(s) responsible for the enhanced staphylococcal adhesion was(were) heat stable. Pretreatment of HeLa cells with the mixture of staphylococcal extracellular antigens and antibodies to them also enhanced the adhesion of Cowan I. Similarly the adhesion of Cowan I was enhanced by pretreatment of HeLa cells with extracellular antigens of Pseudomonas aeruginosa and antibodies to them. These results indicated that cell-bound SpA mediated the binding of S. aureus to immune complexes composed of extracellular bacterial products and antibodies to them bound to the surface of HeLa cells, and suggested another role of cell-bound SpA as a co-adhesin with other factors in infections due to S. aureus.     

Evaluation of monophosphoryl lipid A (MPL) as an adjuvant. Enhancement of the serum antibody response in mice to polysaccharide-protein conjugates by concurrent injection with MPL

Concurrent injection of monophosphoryl lipid A (MPL) in saline or as an oil-in-water emulsion enhanced both the primary and secondary serum antibody responses to the capsular polysaccharide (CP) components of seven conjugates: the enhanced responses were Ag-specific. In contrast, MPL did not enhance the serum antibody response to five of the six unconjugated CP. MPL and trehalose dimycolate injected concurrently with the unconjugated Vi CP of Salmonella typhi (Vi) enhanced the serum antibody response to that Ag. MPL further enhanced the Vi antibody levels when injected with conjugates of this CP. The serum antibody responses to Pseudomonas aeruginosa exotoxin A, used as the carrier protein for the Staphylococcus aureus types 5 and 8 conjugates, were also enhanced by MPL. MPL in oil-in-water emulsion was generally more effective than when administered in saline.     

Enhancing effect of saccharides on the mutagenicity of 2-chloro-4-methylthiobutanoic acid

The mutagenicity of 2-chloro-4-methylthiobutanoic acid (CMBA), a nitrite-treated Sanma fish mutagen, in Salmonella typhimurium TA100 was enhanced by addition of D-glucose during the CMBA-treatment. Several other monosaccharides also enhanced the mutagenicity of CMBA, and the order of the enhancing potency was found to be D-mannose, D-glucose>D-fructose, D-ribose, D-galactose. A disaccharide, maltose, showed only little enhancement. No enhancement was found with L-glucose. We investigated whether saccharides affect uptake of [methyl-14C]CMBA into S. typhimurium TA100. Saccharides which enhanced CMBA-induced mutagenesis increased the uptake. L-Glucose did not enhance the uptake. There was good correlation between the enhanced mutagenesis and increased radioactivity in Salmonella, suggesting that the enhancing effect of monosaccharide on the CMBA-induced mutagenesis results from the enhanced uptake of the mutagen into bacteria.     

Modulation of oral heat and cold pain by irritant chemicals

Common food irritants elicit oral heat or cool sensations via actions at thermosensitive transient receptor potential (TRP) channels. We used a half-tongue, 2-alternative forced-choice procedure coupled with bilateral pain intensity ratings to investigate irritant effects on heat and cold pain. The method was validated in a bilateral thermal difference detection task. Capsaicin, mustard oil, and cinnamaldehyde enhanced lingual heat pain elicited by a 49 degrees C stimulus. Mustard oil and cinnamaldehyde weakly enhanced lingual cold pain (9.5 degrees C), whereas capsaicin had no effect. Menthol significantly enhanced cold pain and weakly reduced heat pain. To address if capsaicin's effect was due to summation of perceptually similar thermal and chemical sensations, one-half of the tongue was desensitized by application of capsaicin. Upon reapplication, capsaicin elicited little or no irritant sensation yet still significantly enhanced heat pain on the capsaicin-treated side, ruling out summation. In a third experiment, capsaicin significantly enhanced pain ratings to graded heat stimuli (47 degrees C to 50 degrees C) resulting in an upward shift of the stimulus-response function. Menthol may induce cold hyperalgesia via enhanced thermal gating of TRPM8 in peripheral fibers. Capsaicin, mustard oil, and cinnamaldehyde may induce heat hyperalgesia via enhanced thermal gating of TRPV1 that is coexpressed with TRPA1 in peripheral nociceptors.     

Regulation of amino acid transport in Thiobacillus thioparus.

Amino acid transport in amino acid auxotrophs of Thiobacillus thioparus was enhanced during growth on rate-limiting amino acid concentration. A pleiotropic mutation enhanced general amino acid transport as manifested by higher values of Vmax of amino acid transport. Affinity constants remained unaltered. Mutants with enhanced transport properties did not show changes in oxidation of thiosulfate, did not oxidize various organic compounds, and did not increase the heterotrophic potential of T. thioparus. The mutations for enhanced transport caused increased synthesis of amino acid transport system components. A method for genetic transformation of T. thioparus is described.     

芒果老叶在增强UV-B辐射处理下的损伤和保护反应

以‘台衣一号’芒果盆栽苗离体老叶为试材,研究增强UV—B辐射条件下芒果老叶的损伤和保护反应。结果表明：UV—B辐射处理使芒果叶片MDA含量和相对电导率升高、叶绿素含量和叶绿素a／b降低,表明叶片受到损伤,且随处理时间延长叶片损伤加重。UV—B辐射处理叶片可溶性蛋白含量、抗氧化酶（SOD、CAT、POD）活性、保护色素（类胡萝卜素、类黄酮）和还原型GSH含量显著高于对照叶片,UV—B辐射处理叶片维生素C含量显著低于对照叶片,表明增强UV—B辐射可诱导叶片细胞通过提高活性氧清除能力和积累保护色素而直接吸收部分UV—B辐射来提高抗增强UV—B辐射损伤的能力。     

紫外辐射对菜豆不同叶位叶片光合及保护酶活性的影响

以菜豆为实验材料,用紫外辐射处理,测定植物各叶位叶片的生理活性。结果表明,紫外辐射条件下,叶片的光合、蒸腾速率先升高,随后迅速降低,辐射处理3 h对光合作用的抑制程度随叶位升高而增加;第1叶气孔导度和胞间CO2浓度随辐射处理略有增加,而第2、3叶的则先升高随后降低;辐射处理使叶绿素含量先降低随后有所增加,但明显增加叶片丙二醛(MDA)含量;紫外辐射处理后,叶片过氧化物酶(POD)活性先升高随后降低,紫外辐射3 h第1叶POD活性比对照降低26.9%,辐射使第1叶超氧化物歧化酶(SOD)活性略有升高,但明显降低第2、3叶的SOD活性。     

Transactivation of epidermal growth factor receptor by enhanced levels of endogenous angiotensin II contributes to the overexpression of Giα proteins in vascular smooth muscle cells from SHR

We earlier showed that the increased expression of Gi proteins exhibited by vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) was attributed to the enhanced levels of endogenous endothelin. Since the levels of angiotensin II (Ang II) are also enhanced in VSMC from SHR, the present study was undertaken to examine the role of enhanced levels of endogenous Ang II in the overexpression of Giα proteins in VSMC from SHR and to further explore the underlying mechanisms responsible for this increase. The enhanced expression of Giα-2 and Giα-3 proteins in VSMC from SHR compared to WKY was attenuated by the captopril, losartan and AG1478, inhibitors of angiotensin converting enzyme, AT₁ receptor and epidermal growth factor receptor (EGFR) respectively as well as by the siRNAs of AT1, cSrc and EGFR. The enhanced inhibition of forskolin-stimulated adenylyl cyclase activity by low concentrations of GTPγS (receptor-independent functions) and of inhibitory responses of hormones on adenylyl cyclase activity (receptor-dependent functions) in VSMC from SHR was also attenuated by losartan. Furthermore, the enhanced phosphorylation of EGFR in VSMC from SHR was also restored to control levels by captopril, losartan, PP2, a c-Src inhibitor and N-acetyl-L-cysteine (NAC), superoxide anion (O₂⁻) scavenger, whereas enhanced ERK1/2 phosphorylation was attenuated by captopril and losartan. Furthermore, NAC also restored the enhanced phosphorylation of c-Src in SHR to control levels. These results suggest that the enhanced levels of endogenous Ang II in VSMC from SHR, transactivate EGFR, which through MAP kinase signaling, enhance the expression of Giα proteins and associated adenylyl cyclase signaling.