春小麦水分胁迫响应中的ACC、MACC合成及乙烯的释放

水分胁迫使两个抗旱性不同的春小麦 (TriticumaestivumL .)品种“8139”(抗旱性较弱 )和“5 0 4”(抗旱性较强 )叶片ACC和MACC含量于胁迫初期下降后期升高 ,ACC合酶活性持续升高 ,乙烯释放量在 8139中下降而在5 0 4中先大幅升高而后下降。两种作用效果相反的抑制剂MGBG (抑制SAMDC活性 )和AOA (抑制ACC合酶活性 )均明显影响了两品种春小麦叶片以上各指标的变化。结果表明 ,水分胁迫下作物乙烯的释放量并不与其合成直接前体ACC的量成正相关 ;胁迫乙烯在抗性品种中于胁迫初期的升高可能是植物胁迫信号传导的响应之一 ,是一种干旱适应现象 ,可能与作物的干旱忍耐形成有关 ,而MACC具有调节胁迫乙烯释放的特殊生理作用。     

干旱期间春小麦叶片多胺含量与作物抗旱性的关系

使用两种抑制剂MCBG(抑制SAMDC活性)和AOA(抑制ACC合成酶活性)研究了干旱期间两个春小麦品种8139(抗旱性较弱)和504(抗旱性较强)叶片多胺(Put、Spd和Spm)含量、RWC水平、SOD和POD活性以及MDA含量的变化,并由此探讨了不同类别多胺与作物抗旱性的关系以及多胺与乙烯在作物对干旱胁迫响应过程中对共同前体SAM的竞争趋向及其生理意义。     

干旱期间春小麦叶片多胺含量与作物抗旱性的关系

使用两种抵制剂ＭＧＢＧ（抑制ＳＡＭＤＣ活性）和ＡＯＡ（抑制ＡＣＣ合成酶活性）研究了干旱期间两个春小麦品种８１３９（抗旱性较弱）和５０４（抗旱性较强）叶片多胺（Ｐｕｔ、Ｓｐｄ和Ｓｐｍ）含量、ＲＷＣ水平、ＳＯＤ和ＰＯＤ活性以及ＭＤＡ含量的变化,并由此探讨了不同类别多胺与作物抗旱性的关系以及多胺与乙烯在作物对干旱胁迫响应过程中对共同前体ＳＡＭ的竞争趋向及其生理意义。     

春小麦不同发育阶段抗氧化系统对田间缓慢干旱的响应

研究了两种抗旱性不同的春小麦(Triticum aestivum L.)品种定西24(抗旱性较强)和品种8139(抗旱性较弱)不同发育阶段体内抗氧化系统对田间缓慢干旱的响应情况。结果表明,在田间自然干旱条件下,随着土壤水分含量的逐渐降低,两品种小麦叶片水势和含水量均缓慢降低,叶片色素及可溶性蛋白含量也于幼苗期显著降低,植株生长受抑。叶片抗氧化酶系统如SOD、：POD、CAT以及GSH—ASC循环中的两种关键酶APX和GR活性,均在小麦发育前期如幼苗期和拔节期显著升高而于后期下降。主要抗氧化物质ASC含量也表现出相似的变化趋势。虽然抗氧化系统在两春小麦品种不同发育阶段对田间干旱的响应行为大体相同,而且干旱较敏感品种8139各物质对干旱的响应强于干旱较耐受品种定西24,但后者减轻干旱导致的氧化损伤的效率高于前者。试验还表明,在作物的不同发育阶段,抗氧化系统对田间缓慢干旱响应的策略不同,前期如幼苗期和拔节期主要表现为积极应对,后期如抽穗期和灌浆期主要表现为被动忍耐。     

接触二氧化硫后小麦叶片中逆境乙烯的生物合成

AVG和AOA强烈抑制二氧化硫处理小麦叶片中乙烯产生和ACC合成,对MACC的形成也有一定的抑制作用。CoGl_2明显抑制乙烯产生,而ACC大量积累,MACC含量则未因ACC增加而相应增加。DNP和CCCP也抑制乙烯产生,但前者引起ACC大量积累,后者引起ACC含量下降。CHI对乙烯产生和ACC形成均显示强烈的抑制作用,同时也明显抑制MACC形成。这表明小麦叶片接触SO_2引起的逆境乙烯也是循蛋氨酸→SAM→ACC→乙烯途径。     

抗旱性不同的小麦幼苗在水分和盐胁迫下抗氧化酶和多胺的变化

分别对抗旱小麦8139和干旱敏感小麦甘麦8号的幼苗进行两周的水分胁迫和NaCl胁迫,并对其叶片中一些生理指标的变化进行了研究,结果表明,水分胁迫下8139中O2^-和H2O2的含量及膜脂过氧化程度均低于敏感品种,胁迫后第七天与第十四天其中SOD与CAT活性明显高于甘麦8号,盐胁迫下两种小麦中的H2O2,MDA含量及SOD,POX酶活性在各时期均无明显差别,水分胁迫下,8139中多胺（腐胺Put,亚精胺Spd,精胺Spm)含量显著高于甘麦8号,盐胁迫下,两品种中多胺含量有胁迫7d后才表现出差异,由此可见,水分胁迫下两品种清除自由基的能力明显不同。而在盐胁迫下则差别不大。表现在生长上,水分胁迫下8139地上部分干物质的累积量高于甘麦8号,而在NaCl胁迫下两者之间差别不大,该结果表明植物抗旱与抗盐的生理保护机理是不一样的。     

外源精胺对水分胁迫下小麦幼苗保护酶活性的影响

通过营养液培养试验,研究了水分胁迫下外源精胺(Spm)对抗旱性不同的小麦品种幼苗叶片质膜相对透性及保护酶活性的影响.结果表明:水分胁迫下,小麦叶片的质膜相对透性、M DA含量增加、SOD、CAT和POD活性上升,外源精胺处理可延缓水分胁迫下小麦叶片质膜相对透性和M DA含量上升,提高了SOD、CAT、POD酶活性的上升幅度;并且对抗旱性弱的品种保护酶活性增幅高于抗旱性强的品种.因此,外源精胺处理对抗旱性弱的品种缓解水分胁迫作用大于抗旱性强的品种.     

不同花生品种响应干旱胁迫后叶片内ABA与AhNCEDl的分布

以粤油7号和汕优523两个不同抗旱性品种为材料,研究响应干旱胁迫后叶片ABA（abscisicacid,脱落酸）和AhNCEDl（Arachishypogaeanine-cis-epoxycarotenoiddioxygenase）的分布以及含量变化。结果表明,两种花生品种响应干旱胁迫后叶片的维管组织中ABA分布增强且含量增加,AhNCEDl蛋白分布也增强;且在水分胁迫初期粤油7号花生AhNCEDl蛋白分布强于汕优523,其体内ABA分布水平也高于汕优523;经ABA生物合成抑制剂N印roxen处理后,两种花生叶片ABA分布减弱,但粤油7号叶片维管组织ABA分布水平仍高于汕优523。结果表明维管组织是干旱胁迫下花生叶片中ABA和AhNCEDl分布的主要区域,且粤油7号花生抗旱性强可能与其体内AhNCEDl和ABA的分布量较高有关。     

不同花生品种响应干旱胁迫后叶片内ABA与AhNCED1的分布

以粤油7号和汕优523两个不同抗旱性品种为材料,研究响应干旱胁迫后叶片ABA(abscisic acid,脱落酸)和AhNCED1(Arachis hypogaea nine-cis-epoxycarotenoid dioxygenase)的分布以及含量变化。结果表明,两种花生品种响应干旱胁迫后叶片的维管组织中ABA分布增强且含量增加,AhNCED1蛋白分布也增强;且在水分胁迫初期粤油7号花生AhNCED1蛋白分布强于汕优523,其体内ABA分布水平也高于汕优523;经ABA生物合成抑制剂Naproxen处理后,两种花生叶片ABA分布减弱,但粤油7号叶片维管组织中ABA分布水平仍高于汕优523。结果表明维管组织是干旱胁迫下花生叶片中ABA和AhNCED1分布的主要区域,且粤油7号花生抗旱性强可能与其体内AhNCED1和ABA的分布量较高有关。     

PEG胁迫及复水对不同抗旱性小麦幼苗脯氨酸代谢关键酶活性的影响

以两种不同抗旱性小麦品种幼苗为试验材料,采用PEG模拟干旱胁迫处理,探究干旱胁迫及复水对小麦幼苗叶片与根系脯氨酸累积及关键酶活性的影响。结果显示:(1)PEG胁迫下抗旱品种‘普冰143’根长和根干重下降不大,而水敏感品种‘郑引1号’根长和根干重下降显著;且于胁迫处理36h时‘普冰143’根系脯氨酸含量增加(75.0%)显著大于‘郑引1号’(37.7%),复水24h后均恢复至对照水平。(2)PEG胁迫下‘普冰143’叶片中谷氨酸合成途径关键酶P5CS和鸟氨酸合成途径关键酶δ-OAT活性均显著增加,且‘普冰143’叶片脯氨酸两条合成途径关键酶活性均得以加强;PEG胁迫处理36h时,‘郑引1号’叶片中P5CS活性增加显著,δ-OAT活性变化较小,且‘郑引1号’叶片脯氨酸合成可能以谷氨酸途径为主;但在PEG胁迫下两个不同抗旱性品种的根中P5CS、δ-OAT活性均变化较小。(3)PEG胁迫处理36h时‘普冰143’叶片脯氨酸降解酶PDH活性显著下降,而‘郑引1号’叶片PDH活性显著增加,复水后抗旱品种叶片该酶活性显著增加,水敏感品种恢复至对照水平;但PEG胁迫处理下两个不同抗旱性品种的根中PDH活性均显著下降。研究表明,PEG胁迫下小麦叶片是合成脯氨酸的主要部位,抗旱品种‘普冰143’根系脯氨酸持续积累与叶片中高的脯氨酸合成关键酶活性及脯氨酸转运有关。     

白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。     

New amino-dithiaphospholanes and phosphoramidodithioites and their rhodium and iridium complexes

New sulfur derivatives of phosphoramidite ligands were synthesized and the impact of the sulfur unit on the spectroscopic properties of their rhodium and iridium complexes was investigated. The new ligands Bn₂NPSCH₂CH₂S^a(P-S^a) (Bn = benzyl, 4), Bn₂NPSCHCHS^a(CH₂)₃C^aH₂(P-S^a)(C^a-S^a) (6) and Bn₂NP(4-XC₆H₄OMe)₂ (X = S, 7a; X = O, 7b) were converted to the rhodium and iridium complexes trans-[Rh(CO)Cl(L)₂] (L = 4, 6, 7), [RhCl(COD)(L)] (L = 4, 6, 7), [IrCl(COD)(7a)] and [IrCl₂Cp∗(6)]. For comparison, some phosphoramidite complexes of these formulations also were synthesized. The new metal complexes were spectroscopically analyzed. For the carbonyl complexes, the ν_CO IR stretching frequencies were lower than for the corresponding phosphite and phosphoramidite ligands. The ¹J_PRh coupling constants for the rhodium complexes with the new ligands were also smaller than for the respective phosphoramidite and phosphite complexes. Finally, the ¹J_PSe coupling constants of the selenides of the new ligands were lower than those of the phosphoramidite ligands but higher than for PPh₃. The spectroscopic data reveal that the new thio ligands 4, 6 and 7a are more electron donating than phosphites and phosphoramidites but less electron donating than PPh₃.     

Astrocytes and Synaptosomes Transport and Metabolize Lactate and Acetate Differently

Astrocytes transport the monocarboxylate acetate, but synaptosomes do not. The reason for this is unknown, because both preparations express monocarboxylate transporters (MCT). The transport and metabolism of lactate, another monocarboxylate, was examined in these two preparations, and the results were compared to those for acetate. Lactate transport is more rapid in astrocytes than in synaptosomes, but of lower affinity (Kms of 17 and 4 mM, respectively). Lactate (0.2 mM) is metabolized to CO2 more rapidly in synaptosomes than in astrocytes (rates of 0.37 and 0.07 nmol x mg protein(-1) x min(-1), respectively). The reason for this is unclear, but cellular differences in lactate dehydrogenase isotype expression may be involved. Acetate is metabolized to CO2 more rapidly in astrocytes than in synaptosomes (rates of 0.43 and 0.02 nmol x mg protein(-1) x min(-1), respectively). This is likely due to cellular differences in the expression of monocarboxylate transporter subtypes.     

Rapporteur report: Basics and technology and metrology and standards

The first and second sessions of the Workshop focussed on the basics of ultrasound and infrasound, their applications in both industry and medicine, and metrology and protection standards for ultrasound applications.     

Relative and combined effects of ethanol and protein deficiency on strontium and barium bone content and fecal and urinary excretion

To elucidate accumulation of minerals in human iliac arteries with aging, the content of minerals was analyzed by inductively coupled plasma atomic emission spectrometry. Bilateral common, internal, and external iliac arteries of 16 men and 8 women, ranging ages from 65 to 93 yr, were examined. It was found that an extremely high accumulation of calcium and phosphorus occurred in the common iliac artery at old age, being higher than that of the internal and external iliac arteries. It should be noted that the accumulation of calcium and phosphorus is the highest in the common iliac artery among the human arteries examined to date. Regarding sexual differences, the content of calcium and phosphorus in the common and internal iliac arteries was higher in women than in men, whereas their content in the external iliac artery was lower in women than in men.     

Prostaglandin and thromboxane production by human and guinea-pig macrophages and leucocytes

The ability of partially purified human and guinea-pig haematogenous cell populations, when cultured in vitro, to metabolise arachidonic acid (AA) has been studied. Supernatants from 24 hour cell culture have been subjected to analysis for products of AA metabolism by gas chromatography with electron-capture detection.The cell types studied were human peripheral blood monocytes (both glass adherent and non-adherent), neutrophils, eosinophils and leukemic leucocytes; thoracic duct lymphocytes and lung alveolar macrophages. From the guinea-pig, induced and non-induced macrophage or neutrophil enriched peritoneal exudate populations, lymph node cells, peritoneal eosinophils and peripheral blood platelets were examined. Supernatants were assayed for the presence of PGE₂, PGD₂, PGF_2α, TXB₂ and 6-keto-PGF_1α. In all types studied PGE₂ and TXB₂ were the major products formed. The identification of PGE₂ and TXB₂ was confirmed by GC/MS with multiple ion monitoring.The results have been compared with other reports and their possible significance discussed in relation to the proposed role of prostaglandins as mediators and modulators in immunopathology.     

Chemokines and cytokines: axis and allies in asthma and allergy

Allergic asthma can be precipitated by many factors. For the atopic person, fungus, pollen, dust mites, cockroach antigens, and diesel exhaust are all agents that may trigger an allergic attack. Cytokines and chemokines are integral mediators of fungal asthma. From the earliest time points, they recruit and activate the cells required for the clearance of fungus as well as being critical factors involved in the immunopathology of this disease. In the final analysis, it is clear that these mediators can act to the benefit or the detriment of the host.     

Oxidation and nitration of ribonuclease and lysozyme by peroxynitrite and myeloperoxidase

In spite of the many studies on protein modifications by reactive species, knowledge about the products resulting from the oxidation of protein-aromatic residues, including protein-derived radicals and their stable products, remains limited. Here, we compared the oxidative modifications promoted by peroxynitrite and myeloperoxidase/hydrogen peroxide/nitrite in two model proteins, ribonuclease (6Tyr) and lysozyme (3Tyr/6Trp). The formation of protein-derived radicals and products was higher at pH 5.4 and 7.4 for myeloperoxidase and peroxynitrite, respectively. The main product was 3-nitro-Tyr for both proteins and oxidants. Lysozyme rendered similar yields of nitro-Trp, particularly when oxidized by peroxynitrite. Hydroxylated and dimerized products of Trp and Tyr were also produced, but in lower yields. Localization of the main modified residues indicates that peroxynitrite decomposes to radicals within the proteins behaving less specifically than myeloperoxidase. Nitrogen dioxide is emphasized as an important protein modifier.