一氧化氮对番茄种子抗吸胀冷害的影响

以番茄毛粉802种子为材料,通过对比实验,测定分析各处理种子的萌发率及第4天的平均根长、萌发指数、活力指数,以及相对电导率(REC)、丙二醛(MDA)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)含量的变化,以探讨NO对番茄种子吸胀冷害的抵抗作用及其机理.结果显示:(1)外源NO可显著提高番茄种子经12 h吸胀冷害处理后的萌发率、平均根长、萌发指数和活力指数,并显著降低吸胀冷害下REC和MDA含量,同时显著提高SOD和CAT的含量.(2)NO所提高的吸胀冷害处理后种子的SOD和CAT活性不能被RNA合成抑制剂放线菌素D和蛋白质合成抑制剂环己酰亚胺抑制.结果表明,NO可提高番茄种子抵抗吸胀冷害的能力,而且与NO激活了抗氧化系统有关,但NO不是通过促进抗氧化酶的合成来提高其活性.     

NaCl胁迫下玉米幼苗中一氧化氮与茉莉酸积累的关系

以三叶一心期的玉米幼苗为材料,研究了NaCl胁迫下玉米幼苗根尖和叶片中一氧化氮(NO)和茉莉酸(JA)积累之间的关系.结果表明:NaCl胁迫下玉米幼苗根尖和叶片中NO和JA的含量均增加,且NO积累的时间早于JA;根尖中脂氧合酶(LOX)活性逐渐降低,而叶片中LOX活性显著升高.硝普钠(SNP,NO供体)处理使幼苗的JA含量和LOX活性亦增加;用NO清除剂cPTIO及NO合成的抑制剂L-NAME、NaN3处理幼苗时,可抑制NaCl胁迫诱导的JA积累以及叶片中LOX活性的增加.可见,玉米幼苗在盐胁迫下爆发的NO可能通过调控LOX活性来调节其JA的积累.     

Cryptococcus neoformans inhibits nitric oxide synthesis caused by CpG-oligodeoxynucleotide-stimulated macrophages in a fashion independent of capsular polysaccharides

Cryptococcus neoformans is eradicated by macrophages via production of NO. Unmethylated CpG-ODN protect mice from infection with this fungal pathogen by inducing IFN-gamma. The present study was designed to elucidate the effect of C. neoformans on the synthesis of NO by alveolar macrophages. For this purpose, MH-S, an alveolar macrophage cell line, was stimulated with CpG-ODN in the presence of IFN-gamma. A highly virulent strain of C. neoformans with thick capsule suppressed the production of NO. Capsular polysaccharides were not essential for this suppression, because there was no difference between acapsular mutant (Cap67) and its parent strain. Physical or close interaction of Cap67 with MH-S was necessary, as shown by the loss of such effect when direct contact was interfered by nitrocellulose membrane. Similar effects were observed by disrupted as well as intact Cap67. Whereas the inhibitory effect of intact Cap67 was completely abrogated by heat treatment, disrupted Cap67 did not receive such influence. Finally, disrupted Cap67 did not show any inhibitory effect on the TLR9-mediated activation of NF-kappaB in a luciferase reporter assay with HEK293T cells, although the TLR4-mediated activation was suppressed. These results revealed that C. neoformans suppressed the synthesis of NO by CpG-ODN and IFN-gamma-stimulated macrophages in a fashion independent of capsular polysaccharides, although the precise mechanism remains to be elucidated.     

Decrease in DEET repellency caused by nitric oxide in Rhodnius prolixus

N,N-diethyl-3-methylbenzamide (DEET) is widely used as an insect repellent; however, little is known about its mode of action. On the other hand, nitric oxide (NO) participates in the olfaction transduction pathway of insects. In this work, nitroso-acetyl-cysteine (SNAC), a nitric oxide donor, or dibutyril-cyclic-GMP (db-cGMP), the cyclic nucleotide analog, were applied on fifth instar nymphs of Rhodnius prolixus before exposing them to DEET, to obtain information about the possible role of NO/cGMP system in the olfaction process. In the first place, we exposed the nymphs to several DEET concentrations (70, 700, 1,750, and 3,500 microg/cm2). All these concentrations produced a repellent effect. A decrease in repellency during the course of the experiment was observed when the nymphs were exposed to high concentrations of DEET (700 and 1,750 microg/cm2), suggesting an adaptation phenomenon. The pre-treatment of the insects with 15 microg /insect of SNAC or 2 microg/insect of db-cGMP produced a reduction of the repellency. An increase in locomotor activity was observed in insects exposed to 350 or 700 microg/cm2 DEET. Although exposure to 70 microg/cm2 DEET produced a high repellency response, it did not modify the insects' locomotor activity. Insects treated with two doses of SNAC before being exposed to 350 microg/cm2 of DEET showed no differences in locomotor activity compared to controls.     

Nitric oxide extends the oocyte temporal window for optimal fertilization

Deteriorating oocyte quality is a critical hurdle in the management of infertility, especially one associated with advancing age. In this study, we explore the role of nitric oxide (NO) on the sustenance of oocyte quality postovulation. Sibling oocytes from superovulated mice were subjected to intracytoplasmic sperm injection (ICSI) with cauda-epididymal spermatozoa following exposure to either the NO donor, S-nitroso-N-acetylpenicillamine (SNAP, 0.23 microM/min), an NO synthase (NOS) inhibitor, N omega-nitro-L-arginine methyl ester (L-NAME, 1 mM), or an inhibitor of soluble guanylyl cyclase (sGC), 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, 100 microM); while their sibling oocytes were subjected to ICSI either before (young) or after culture for the corresponding period of time (old). Outcomes of normal fertilization, cleavage, and development to the morula and blastocyst stages were compared. Embryos from each subgroup were also subjected to TUNEL assay for apoptosis. A significant deterioration in the ability of the oocytes to undergo normal fertilization and development to morula and blastocyst stages occurred among oocytes aged in culture medium compared to their sibling cohorts subjected to ICSI immediately after ovulation (P<0.05). This deterioration was prevented in oocytes exposed to SNAP. In contrast, exposure to L-NAME or ODQ resulted in a significant compromise in fertilization and development to the morula and blastocyst stages (P<0.05). Finally, apoptosis was noted in embryos derived from aged oocytes and those exposed to L-NAME or ODQ, but not in embryos derived from young oocytes or oocytes exposed to SNAP. Thus, NO is essential for sustenance of oocyte quality postovulation.     

Hepatoprotective phytocompounds from Cryptomeria japonica are potent modulators of inflammatory mediators

Cryptomeria japonica is an important plantation conifer tree in Asia. This study aimed to characterize the anti-inflammatory and hepatoprotective activities of the phytocompounds from C. japonica wood on LPS- or TPA-induced activation of proinflammatory mediators and CCl(4)-induced acute liver injury in mice. A CJH7-2 fraction was purified from C. japonica extracts following bioactivity-guided fractionation, and it exhibited significant activities on inhibition of NO production and iNOS expression as well as up-regulating HO-1 expression in LPS-stimulated macrophages. CJH7-2 also potently inhibits COX-2 enzymatic activity (IC(50)=5 microg/mL) and TPA-induced COX-2 protein expression in mouse skin (1mg/200 microL/site). CJH7-2 (10 mg/kg BW) can prevent CCl(4)-induced liver injury and aminotransferases activities in mice. Chemical fingerprinting analysis showed that terpenes are the major bioactive compounds in the CJH7-2 fraction. This is the first study to demonstrate that chemical constituents from the wood extract of C. japonica possess anti-inflammatory activities in vitro and in vivo that may play a role in hepatoprotection.     

Stimulus (polyphenol, IFN-gamma, LPS)-dependent nitric oxide production and antileishmanial effects in RAW 264.7 macrophages

The effects of interferon (IFN-γ), lipopolysaccharide (LPS), and some polyphenols as individual stimuli, as well as in various combinations on NO production in non-infected and infected macrophage-like RAW 264.7 cells were investigated, with emphasis on the NO/parasite kill relationship. In non-infected and in Leishmania parasitized cells, gallic acid significantly inhibited the IFN-γ and LPS-induced NO detected in the supernatant. This effect was less prominent in IFN-γ- than in LPS-stimulated cells. Interestingly, and in contrast to non-infected cells, gallic acid inhibited NO production only when added within 3 h after IFN-γ + LPS. Addition of gallic acid following prolonged incubation with IFN-γ + LPS periods (24 h) no longer inhibited, sometimes even enhanced NO release. Notably, an excellent NO/parasite kill relationship was evident from all the experiments. This study was extended to a series of polyphenols (3-O-shikimic acid, its 3,5-digalloylated analogue, catechin, EGCG, and a procyanidin hexamer) with proven immunostimulatory activities. Although these compounds themselves were found to be weak NO-inducers, the viability of intracellular Leishmania parasites was considerably reduced. Furthermore, their dose-dependent effects on macrophage NO release was determined in the presence of IFN-γ and/or LPS. Again, non-infected and infected cells differed significantly in the NO response, while inhibition of IFN-γ and/or LPS-induced NO production by the tested polyphenols strongly depended on the given time of exposure and the sequence of immunological stimuli. A strong inverse correlation between NO levels and intracellular survival rates of Leishmania parasites supported the assumption that the observed inhibition of NO was not simply due to interference with the Griess assay used for detection.     

Synthesis and molecular structure of 14,15-pyrrolidino-and 14,16-ethano derivatives of estrone

Hydrolysis of 3-methoxy-16alpha-nitro-14,17-ethenoestra-1,3,5(10)-trien-17beta-yl acetate under weakly basic conditions leads to formation of 3-methoxy-2'-oxopyrrolidino-[4',5':14beta,15beta]-estra-1,3,5 (10)-trien-17-one, the structure of which has been confirmed by X-ray analysis and some chemical transformations. The reactivity of 3-methoxy-16alpha-nitro-14,17-ethanoestra-1,3,5(10)-trien-17beta-yl acetate under various conditions of basic hydrolysis has been investigated. The derived compounds have been identified by means of NMR spectroscopy and X-ray analysis.     

土壤生物多样性与微量气体(CO2、CH4、N2O)代谢

土壤生物是重要的基因库 ,土壤生物多样性是全球生物多样性的重要组成部分。土壤生物是C、N地球化学过程 (土壤库 )的驱动者 ,调控微量气体代谢。在微量气体代谢中 ,土壤微生物具有直接的作用。真菌、CH4 生成菌、CH4 氧化菌、硝化菌以及反硝化菌等是调控微量气体代谢的关键生态功能类群。由于相对大的体积和强大的酶化学分解作用 ,真菌通常主导枯枝落叶的分解活动。“通气—厌气”界面是微生物群落的活跃区域 ,易发生微量气体代谢。“有机—无机”过渡层、水生植物根际区、土壤动物肠道系统是典型的微量气体代谢界面。土壤动物对微量气体代谢的作用通常为前期的和间接的 ,并且又是重要的。节肢动物 (白蚁 )和环节动物 (蚯蚓 )是分别代谢CH4 和N2 O的两个关键性生态功能类群。在研究土壤生物多样性及其对微量气体代谢的作用方面 ,由于土壤生态系统的复杂性 ,需综合传统微生物实验技术与现代同位素技术和分子生物学技术。我国缺乏研究土壤生物多样性及其对微量气体代谢影响的实质性工作 ,有必要开展这方面的研究。     

Stimulatory Effect of Leptin on Nitric Oxide Production Is Impaired in Dietary‐Induced Obesity

Objective: We investigated the effect of leptin on nitric oxide production in lean and rats made obese by a high‐calorie diet. Research Methods and Procedures: The animals were placed in metabolic cages, and urine was collected in 2‐hour periods after leptin (1 mg/kg intraperintoneally) or vehicle administration. Blood was obtained 0.5, 1, 2, 4, or 6 hours after injection. Results: Leptin had no effect on systolic blood pressure in either lean or obese animals. Plasma concentration of NO metabolites (nitrites + nitrates, NO_x) increased in lean rats by 31.5%, 58.0%, and 27.9% at 1, 2, and 4 hours after leptin injection, respectively. In the obese group, plasma NO_x increased only at 2 hours (+36.5%). Leptin increased urinary NO_x excretion by 31.8% in the first 2‐hour period after injection in lean but not in obese rats. In lean animals, leptin elevated plasma cyclic 3′, 5′‐guanosine monophosphate (cGMP) at 1, 2, and 4 hours by 35.3%, 96.3%, and 57.3%, respectively. In the obese group, plasma cGMP was higher only at 2 and 4 hours (+44.6% and +32.1%, respectively). Urinary excretion of cGMP increased in lean animals by 67.1% in the first period and by 50.4% in the second period. In the obese group, leptin induced a 53.9% increase in urinary cGMP excretion only in the first 2‐hour period. Discussion: The stimulatory effect of leptin on NO production is impaired in dietary‐induced obesity; however, leptin does not increase blood pressure in obese animals, suggesting that other NO—independent depressor mechanisms are stimulated.