Specific Features of the Formation of a Halo during Pathogenesis as a Response of Cereal Epidermal Cells to Penetration of Powdery Mildew Causative Agents

A cytophysiological study was carried out of the functional status of a halo as a response of the host plant to contact with a powdery mildew pathogen. Interactions of the powdery mildew causative agents with barley, wheat, wheat–wheat-grass hybrids, wheat-aegilops lines, and aegilops with different genotypic resistance lead to the expression of haloes during pathogens, which are induced by infection pegs of the primary growth tubes, appressoria, and hyphal lobes. Haloes are visualized using cytochemical reactions to proteins and scanning electron microscopy. The observed differences in the size of haloes and intensity of their staining (uniform or zonal) are related, to a great extent, to individual reactions of the plant cell at the penetration site and, to a lesser extent, to the level of genotypic resistance. An analysis of electron microscopy and cytochemistry studies suggests that the halo as a physiologically active zone is localized at the level of the plant cell plasmalemma. Active taxis of the cell organelles to the site of infection during the formation of a halo suggests that some kind of informational signals to changes in the cell metabolism are spread from the halo zone, which lead to compatible or incompatible interactions.     

Factors controlling induction of commitment of murine erythroleukemia (TSA8) cells to CFU-E (colony forming unit-erythroid)

On addition of DMSO, the MEL cell line TSA8 becomes committed into erythroid progenitor cells (CFU-E) which can form differentiated colonies in the presence of erythropoietin. To understand the mechanism of cellular commitment, the number and the affinity of the receptors for erythropoietin were estimated. The affinity of the receptors did not change before or after induction. The number of receptors changed depending on the growth phase, but was not dependent on the addition of the inducer. Thus, the presence of the receptors for erythropoietin may be required, but are not essential for responsiveness to erythropoietin. Further examination of the optimum conditions for commitment suggests that the concomitant actions of induced factor(s) with the receptors may control commitment of TSA8 cells to CFU-E.     

正常小鼠高频心电图时域值和功率谱的研究

本文用南京新博公司生产的ＮＨＥ－１０００型心电高频信息检测分析仪研究了正常小鼠（昆明种）高频心电图（ＨＦ－ＥＣＧ）的时域值和ＱＲＳ波群的功率谱。主要结果如下（以正导为例,－Ｘ±ＳＤ）：心率６０３±８８次／ｍｉｎ（ｎ＝７４）;Ｐ－Ｒ间期相对较长。为３４．９±４．７ｍｓ（ｎ＝５８）,占心动周期的３４．９±４．９％,这与人类有很大的不同;ＱＲＳ波宽９．２±１．２ｍｓ,占心动周期的９．２±１．４％（ｎ＝７４）,这一结果与以前的文献报道相差较大。Ｔ波宽１０．３±３．２ｍｓ,占心动周期的１０．３±３．２％;Ｑ－Ｔ间期１９．４±３．２ｍｓ,占心动周期的１９．５±３．６％;ＱＲＳ波群峰－峰值（Ｖｐ－ｐ）为１．４５６±０．４８０ｍＶ;Ｔ波高０．３３６±０．１１５ｍＶ;７３只动物Ⅱ导联高频切迹总数只有３个,扭挫２６个。Ⅱ导联ＱＲＳ波群的功率谱特点：０—８０Ｈｚ的相对能量为４５．４８±１５．３２％;８０—２００Ｈｚ为４３．９７±９．９５％;２００—３００Ｈｚ为８．８９±７．３８％;３００—１０００Ｈｚ为１．６６±２．７４％。     

A ring of uncharged polar amino acids as a component of channel constriction in the nicotinic acetylcholine receptor.

The channel pore of the nicotinic acetylcholine receptor (AChR) has been investigated by analysing single-channel conductances of systematically mutated Torpedo receptors expressed in Xenopus oocytes. The mutations mainly alter the size and polarity of uncharged polar amino acid residues of the acetylcholine receptor subunits positioned between the cytoplasmic ring and the extracellular ring. From the results obtained, we conclude that a ring of uncharged polar residues comprising threonine 244 of the alpha-subunit (alpha T244), beta S250, gamma T253 and delta S258 (referred to as the central ring) and the anionic intermediate ring, which are adjacent to each other in the assumed alpha-helical configuration of the M2-containing transmembrane segment, together form a narrow channel constriction of short length, located close to the cytoplasmic side of the membrane. Our results also suggest that individual subunits, particularly the gamma-subunit, are asymmetrically positioned at the channel constriction.     

Effects of the anti-lipogenic antibiotic cerulenin on growth and fatty acid composition of n-alkane-utilizingCandida lipolytica

Summary The effects of cerulenin, an anti-lipogenic antibiotic, on the growth and cellular fatty acid composition ofCandida lipolytica were investigated by changing the chain length of n-alkane, the growth substrate. The antibiotic inhibited almost completely the growth of the yeast on glucose, n-undecane and n-dodecane, but partly that on n-tridecane. The yeast growth on longer alkanes, e.g., from n-tetradecane to n-octadecane, was not affected by this antibiotic, indicating that a chain elongation system and/or intact incorporation system predominantly operate in the formation of cellular fatty acids from such longer chain n-alkanes. Comparison of the fatty acid profiles between the cells grown on n-alkanes of different chain lengths, especially on n-pentadecane, in the presence and absence of cerulenin, supported the supposition that only the de novo synthesis system of the yeast would be affected by the antibiotic, whereas the chain elongation system would not.     

17个建兰品种光合特性分析

以17个建兰(Cymbidium ensifolium)品种为材料,采用改良的丙酮法提取叶绿素,再通过Arnon丙酮法公式计算光合色素含量,利用捷克FluorCam开放式叶绿素荧光仪测定不同品种的叶绿素荧光参数。结果表明,17个建兰品种的光合色素和叶绿素荧光参数具有不同程度的差异,其中‘铁骨素’(C. ensifolium ‘Tiegusu’)、‘逸红双娇’(C. ensifolium ‘Yihongshuangjiao’)和‘闽南黄蝶’(C. ensifolium ‘Minnanhuangdie’)的光合色素含量高于其他品种,表明这3个品种具有良好的光合效率,吸收光能的能力较强;‘铁骨素’最大荧光产量(Fm)、Kautsky诱导效应最大荧光(Fp)、PS Ⅱ原初光能转化效率(Fv/Fm)和非光化荧光淬灭系数(NPQ)均为最高。综上可知,‘铁骨素’的光合生理特性优于其他品种,可作为优良建兰品种进行种植推广。     

小叶锦鸡儿天然居群叶形态性状变异研究

为揭示小叶锦鸡儿(Caragana microphylla)天然居群叶形态性状的变异规律及其生态适应性特征,该研究以10个小叶锦鸡儿天然居群为对象,通过多重比较、巢式方差分析、相关性分析、聚类分析和主成分分析等方法,对7个叶形态性状进行分析。结果表明：(1)小叶锦鸡儿叶形态性状在居群内和居群间均存在极显著差异(P < 0.01),平均变异系数为10.13%,不同性状的变异幅度为6.23%~12.78%;平均叶形态性状的表型分化系数为43.62%,居群内变异(30.09%)大于居群间变异(24.91%),说明居群内是其叶形态性状变异的主要来源。(2)相关性分析表明,环境因子对小叶锦鸡儿的叶形态性状变异有很大的影响,在地理空间上主要呈现出沿海拔梯度的变异模式;主成分分析的结果显示,小叶宽、叶柄宽和叶柄长对小叶锦鸡儿叶形态变异起主导作用;利用欧式距离对小叶锦鸡儿居群进行UPGMA聚类分析结果显示,基于叶形态性状和环境因子可分别将小叶锦鸡儿10个居群分为3类和2类,Mantel检验结果表明,小叶锦鸡儿的叶形态性状变异不存在地理连续性。研究结果为小叶锦鸡儿的适应性进化和开发利用提供了理论依据。     

H2S作为下游信号参与SA对低温弱光下黄瓜幼苗光合作用的调控

水杨酸(SA)和硫化氢(H₂S)在调控非生物胁迫下植物生长发育和生理代谢中均起着非常重要的作用,但二者作为信号分子在调控低温弱光下黄瓜光合作用中的互作关系还不清楚。本试验以黄瓜幼苗为试材,分别用SA和硫氢化钠(NaHS,H₂S供体)及其清除剂或抑制剂喷撒叶面,以适宜温光下去离子水处理为对照(CK),研究低温(8 ℃/5 ℃,昼/夜)弱光(100 μmol·m^-2·s^-1)下SA和H₂S对黄瓜幼苗光合作用的调控及互作关系。结果表明: SA可明显增强L-/D-半胱氨酸脱巯基酶(LCD、DCD)活性及其mRNA表达,促进内源H₂S产生;NaHS对苯丙氨酸解氨酶和异分支酸合成酶活性、mRNA表达量及内源SA含量影响不大。SA和NaHS可使低温弱光下黄瓜幼苗的光合速率、气孔导度和蒸腾速率明显提高,胞间CO₂浓度显著降低;同时增强核酮糖-1,5-二磷酸羧化酶、Rubisco活化酶、景天庚酮糖-1,7-二磷酸酯酶和果糖-1,6-二磷酸醛缩酶活性及其mRNA表达,促进光合碳同化;提高光下PSⅡ实际光化学效率和暗下PSⅡ最大光化学效率,从而减轻低温弱光胁迫对黄瓜幼苗的光合机构的损伤和生长量的影响。H₂S清除剂次牛磺酸(HT)可使SA对低温弱光下黄瓜幼苗的光合作用和生长促进效应明显减弱,而SA抑制剂多效唑和氨基茚磷酸对H₂S诱导的黄瓜幼苗光合机构对低温弱光的耐受性无显著影响,说明H₂S作为SA的下游信号,参与调控低温弱光下黄瓜幼苗的光合作用。     

生物炭配施氮肥对典型黄河故道区土壤理化性质和冬小麦产量的影响

探讨典型黄河故道区生物炭配施氮肥对耕层土壤理化性质和作物产量的影响,阐明生物炭配施氮肥后土壤碳氮含量和理化性质的变化规律,可为合理培肥土壤、提升耕地质量、提高冬小麦产量提供科学依据。本研究以黄河故道典型区域潮土和中性生物炭为供试材料,连续两年进行田间定位试验,开展不同生物炭用量(0、15、30 t·hm^-2)配施氮肥(N 270、330 kg·hm^-2)对土壤理化性质的影响研究。结果表明: 生物炭施入2年后,土壤广义土壤结构指数(GSSI)增大、土壤三相结构距离指数(STPSD)减小,显著改善了土壤三相比,其中在30 t·hm^-2施炭量条件下土壤三相比最接近理想状态;土壤紧实度和容重降低,土壤总孔隙度和毛管孔隙度增加,田间持水量和透水透气性增大,土壤板结状况得到缓解;>0.25 mm粒径团聚体显著增加(增幅70.6%～94.4%),团聚体平均重量直径(MWD)增大(增幅24.0%～48.0%),土壤团聚体结构得到改善。施加生物炭可显著增加土壤有机碳含量(增幅15.8%～67.0%),并可调节土壤C/N,降低氮素释放强度,提高氮肥利用率,显著增加土壤肥力,但未提高土壤pH值,其中10～20 cm土层土壤pH值呈显著下降趋势。在相同施氮条件下,施用生物炭比不施用处理的冬小麦产量2年平均增加9.6%～25.6%,增产效果显著;在相同生物炭施用量下,高氮处理比常规氮处理的冬小麦平均增产2.5%～4.4%,但差异不显著。综上,生物炭配施氮肥能够改善土壤微生态环境,提高土壤肥力,增加作物产量。从改善土壤理化性质、作物增产效果和投入成本等方面综合考虑,推荐在黄河故道区耕作层施入生物炭30 t·hm^-2并配施氮肥330 kg·hm^-2较为适宜。