三峡库区泥、沙沉降对低位狗牙根种群的影响

三峡库区消落带植物恢复不仅面临长期淹水逆境,还面临泥沙、干旱等环境因素的胁迫.2009年实验、调查研究了三峡库区长寿段低位消落带的狗牙根(Cynodon dactylon L.)种群,探讨了泥、沙沉降对狗牙根种群的影响.结果表明,泥沉降和沙沉降均显著促进了狗牙根芽的萌发,而抑制了狗牙根的芽形成和萌发苗的生长,且前者的抑制作用显著大于后者.泥沉降导致总芽数、萌发苗的茎长和茎宽分别比对照低65.4%(P＜0.05)、97.0%(P＜0.05)、31.2%(P＜0.05),而沙沉降导致前述参数分别比对照低17.1%(P＜0.05)、21.2%(P＜0.05)、1.0%(P>0.05).分别将被沉降泥掩埋的狗牙根移植、掩埋于12cm厚的泥和沙中,40d后对照和S'd组(覆盖沙)狗牙根芽萌发后均能在地面上形成正常的分株,而S'1组(覆盖泥)的萌发芽无法穿透覆盖层,形成分株.S'1组狗牙根芽的萌发率显著高于对照和S'd组,但其萌发苗的茎长和茎节数均显著低于对照,分别为对照的30.3%(P＜0.05)、80.4%(P＜0.05);而S'd组分株的茎长、茎节数、叶片数、叶长和叶宽均显著高于对照组,分别比后者高87.9%(P＜0.05)、53.0%(P＜0.05)、24.2%(P＜0.05)、23.4%(P＜0.05)和24.1%(P＜0.05).S'1组萌发苗的鲜质量、干质量和干鲜质量比分别比对照组低83.3%(P＜0.05)、86.2%(P＜0.05)、15.8%(P＜0.05);而S'd组萌发苗的鲜质量、干质量和干鲜质量比分别比对照组高76.8%(P＜0.05)、110.1%(P＜0.05)、20.0%(P＜0.05).表明,低位消落带的狗牙根对沙沉降具有较强的适应能力,而对泥沉降的适应能力较低,泥沉降是库区低位消落带狗牙根种群恢复的主要影响因素之一.     

三峡库区172m蓄水期间泥、沙沉降对低位狗牙根种群的影响

三峡库区消落带植物恢复不仅面临长期淹水逆境,还面临泥沙、干旱等环境因素的胁迫。2009年实验、调查研究了三峡库区长寿段低位消落带的狗牙根(Cynodon dactylon L.)种群,探讨了泥、沙沉降对狗牙根种群的影响。结果表明,泥沉降和沙沉降均显著促进了狗牙根芽的萌发,而抑制了狗牙根的芽形成和萌发苗的生长,且前者的抑制作用显著大于后者。泥沉降导致总芽数、萌发苗的茎长和茎宽分别比对照低65.4%(P<0.05)、97.0%(P <0.05)、31.2%(P <0.05),而沙沉降导致前述参数分别比对照低17.1%(P<0.05)、21.2%(P<0.05)、1.0%(P>0.05)。分别将被沉降泥掩埋的狗牙根移植、掩埋于12cm厚的泥和沙中,40d后对照和S'_d组(覆盖沙)狗牙根芽萌发后均能在地面上形成正常的分株,而S'_l组(覆盖泥)的萌发芽无法穿透覆盖层,形成分株。S'_l组狗牙根芽的萌发率显著高于对照和S'_d组,但其萌发苗的茎长和茎节数均显著低于对照,分别为对照的30.3%(P<0.05)、80.4%(P<0.05);而S'_d组分株的茎长、茎节数、叶片数、叶长和叶宽均显著高于对照组,分别比后者高87.9%(P<0.05)、53.0%(P<0.05)、24.2%(P<0.05)、23.4%(P<0.05)和24.1%(P<0.05)。S'_l组萌发苗的鲜质量、干质量和干鲜质量比分别比对照组低83.3%(P<0.05)、86.2%(P<0.05)、15.8%(P<0.05);而S'_d组萌发苗的鲜质量、干质量和干鲜质量比分别比对照组高76.8%(P<0.05)、110.1%(P<0.05)、20.0%(P<0.05)。表明,低位消落带的狗牙根对沙沉降具有较强的适应能力,而对泥沉降的适应能力较低,泥沉降是库区低位消落带狗牙根种群恢复的主要影响因素之一。     

三峡库区多年高水位运行对消落带狗牙根生长恢复的影响

为深入了解三峡库区多年高水位运行对消落带优势植物生长恢复的影响,分别于2008年和2017年定量调研了库区长寿段消落带狗牙根(Cynodon dactylon)种群的变化,探讨了库区高水位运行对消落带狗牙根萌发、生长和物质分配的影响。结果表明,多年的高水位运行导致不定芽形成和萌发显著被促进,形成更多的分株;高水位运行导致狗牙根分株的株高、茎宽和叶片数被显著抑制,而叶长和种群的总叶片数被显著促进,且随着消落带水位的降低叶长呈降低趋势,而叶宽和总叶片数呈增加趋势;高水位运行导致狗牙根种群匍匐茎和地下茎的茎长、茎节数和总茎长均被显著促进,且随着消落带水位降低匍匐茎茎长和茎节数呈显著的降低趋势,而地下茎茎长和茎节数呈增加趋势;高水位运行导致狗牙根地下茎储存的干质量呈增加趋势,而分株和匍匐茎的干质量呈降低趋势,而且在种群物质分配中地下茎所占的比例呈增大趋势,低水位狗牙根种群的分株和高水位种群的匍匐茎所占的比例也呈增加趋势。因此,狗牙根不仅具有很强的耐淹和生长恢复能力,也具有很强的拓殖能力,可以作为库区中低位消落带恢复和重建的主要原生物种。     

蓄水后洪水胁迫对三峡库区消落带狗牙根幼苗生长的影响

为了进一步评估蓄水期后三峡库区消落带狗牙根的水淹耐受能力, 于蓄水期后引种库区消落带狗牙根植株, 模拟洪水发生时水下无光、淹水逆境, 探讨洪水复合胁迫持续时间对其后期生长恢复的影响。结果表明: 洪水胁迫显著抑制狗牙根分株的生长发育, 随着胁迫时间的延长其分株数、分株茎长、分株总茎长、分株茎宽、分株叶片数、分株总叶片数均显著低于对照, 仅短期(20 d)胁迫促进了分株叶片的伸长; 短期(20 d)胁迫促进了分枝数、分枝直径和分枝茎节长的生长, 分别比对照增加 20.0%(P<0.05)、15.0%(P<0.05)、18.2%(P<0.05), 但是随着洪水胁迫时间的延长, 狗牙根的分枝数、分枝长、总分枝长、分枝直径、分枝茎节长、分枝茎节数、分枝总茎节数均呈降低趋势; 随着洪水胁迫时间的延长植株叶片光合作用能力也呈降低趋势, 原初光化学效率、实际光化学效率、电子传递速率、光化学淬灭系数显著低于对照, 而非光化学淬灭系数则相反, 表明能量更多的以热的形式被耗散掉, 参与 CO2 固定的电子数显著减少, 光合产物显著降低。因此, 三峡库区消落带狗牙根幼苗对洪水复合胁迫的耐受能力较强, 胁迫时间≥40 d 后其耐受能力呈显著降低趋势, 会导致库区消落带(特别是低水位消落带)狗牙根种群衰退演替加快。     

狗牙根营养繁殖体对模拟水淹的生物学响应

研究了水淹条件下狗牙根(Cynodon daetylon)繁殖体的形态特征和生物量的变化及其水淹后的恢复状况.结果表明,水淹深度的增加会诱导植株茎快速增高,而叶片数则明显下降.水淹时间对植株叶片数、茎直径、茎与根长比的影响显著,而对分枝数、茎长、根长、茎节数不显著.植株地上部生物量和总生物量随着水淹时间的延长而显著减少,但地下部生物量的变化不显著.所有实验处理的植株水淹后都能存活且恢复生长.但水淹对恢复期植株的生长仍有影响,植株的茎长、根长、分枝数、直径、叶片数、叶长、宽度以及叶的长宽比都随水淹时间的延长而显著减少,但茎节数与叶片数的差异不显著.根、茎、叶生物量和植株总生物量也随着水淹时间的延长而减少.实验表明狗牙根繁殖体通过延长茎长、改变叶形和减少生物量等方式对水淹显示出较强的耐受能力.     

两种水分生态型小叶章的生理生态特征研究

通过野外调查与控制试验相结合的方法,比较研究了两种水分生态型小叶章的生理生态特征,结果表明:(1)自然条件下,小叶章沼泽化草甸群落Simpson多样性指数显著高于小叶章草甸群落,但是小叶章草甸群落中小叶章种群生物量显著高于沼泽化草甸群落;草甸小叶章的株高、节长、叶长、叶宽及叶绿素含量均显著高于沼泽化草甸小叶章;叶片干重和叶鞘干、鲜重以及叶片与叶鞘生物量分配比为沼泽化草甸小叶章较高,而茎的干、鲜重和叶片鲜重、总地上生物量及茎生物量分配比均为草甸小叶章较高,但差异均不显著.(2)在人工控制水位条件下,两种生态型小叶章种群密度差异显著,而种群高度则无显著差异;两种生态型小叶章在0 cm、20 cm水位梯度下的叶长,30 cm水位梯度下的叶宽,以及0 cm水位梯度下的叶面积均存在显著差异,沼泽化草甸小叶章个体生长指标均对水位梯度具有显著响应,而典型草甸小叶章仅叶绿素含量对水位梯度具有显著响应.研究发现,两种生态型小叶章对水位条件的敏感程度不同,不同条件下对水位梯度具有不同的响应规律.     

不同厚度沙埋下植物光合特性变化与补偿性生长的关系

在自然条件下通过对海岸沙地不同株型单叶蔓荆(Vitextrifolia var.simplicifolia Cham)在不同厚度沙埋处理下土壤温度、湿度,沙上叶片鲜重(FW)和干重(DW)、叶片净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)的测定以揭示沙埋后植物的快速生长与光合作用的关系以及植物补偿性生长在其耐沙埋中的作用。结果表明,不同厚度沙埋下,土壤表层含水量最低和温度最高(40℃),随着沙埋厚度增加,土壤含水量显著增加,而土壤温度(28℃)降低。轻度和中度沙埋5 d和10 d,幼株和成株沙上叶片鲜重(FW)和干重(DW)增加,单叶蔓荆成株沙上顶部叶片FW分别较对照增加27%和29%;DW较对照增加23%和27%,并与对照差异显著(P0.05)。幼株和成株单叶蔓荆对照和不同厚度沙埋下沙上叶片Pn、Tr、Gs日变化曲线均呈现"双峰型",且植株上部叶片Pn、Tr、Gs高于下部叶片。但在轻度和中度沙埋处理下,幼株和成株单叶蔓荆叶片Pn、Tr、Gs增加并高于对照,成株在光合第一个高峰期顶部叶片Pn分别较对照高13%和24%,Tr分别较对照增加33%和72%,Gs较对照分别增加了55%和27%。研究表明,沙埋下植株快速生长和叶片物质积累加速与光合作用增高呈正相关。沙埋胁迫激活植株补偿生长是引起植物Pn增加,干物质积累的主要原因。而沙埋使叶片损失导致植物能量代谢失衡是激活补偿生长的内因,沙埋使植物下部处于低温潮湿环境是补偿生长的外因。沙埋胁迫下植物补偿生长在其维持能量和物质代谢平衡和适应沙埋中起重要作用,是单叶蔓荆适应沙埋的重要生理调控策略。     

不同水分处理对狗牙根种内相互作用的影响

以狗牙根当年生扦插苗为试验材料,根据库区河岸带水分特征设置4种水分处理方式:水分对照组(CK)、水淹与干旱交替组(FD)、土壤水分饱和组(LF)和全淹组(FL),4种密度方式:对照(1株/盆)、低密度(2株/盆)、中密度(4株/盆)及高密度(12株/盆),探究狗牙根生长及形态响应,并验证胁迫梯度假说。结果表明:(1)狗牙根各生物量随水分胁迫强度的增加显著下降(P0.001);密度处理和二者交互作用显著影响狗牙根叶干重、茎干重、根干重、地上生物量和总生物量(P0.001)。(2)水分处理显著影响狗牙根各形态指标(P0.001);密度和二者交互作用显著影响狗牙根分枝数、总茎长和节间长(P0.001)。(3)CK组和LF组狗牙根生物量相对邻体效应(RNE)均为负值,表明其种内关系为竞争关系。FL组各密度组生物量RNE值均为正值,其种内关系转化为促进关系。(4)中高密度组总茎长RNE值随水分胁迫增加而增大。研究表明:(1)狗牙根对不同的水分胁迫均表现出积极响应,可考虑将狗牙根用于库区河岸带植被重建。(2)随种植密度的增大,狗牙根生长及形态均表现出一定的负面效应。(3)本试验在一定程度上支持胁迫梯度假说,但尚需更多概念模型将其改进完善。     

沙埋对无芒雀麦种子萌发和幼苗生长的影响

研究了沙埋对浑善达克沙地植物群落中多年生禾草无芒雀麦种子萌发、出苗和幼苗生长的影响.结果表明:无芒雀麦种子能在深度≤12cm的沙埋中萌发,≤8cm的沙埋中出苗.在此范围内,随着沙埋深度的增加,无芒雀麦种子的萌发率和出苗率逐渐降低.沙埋深度在植株高度的33%时,无芒雀麦1周龄和2周龄幼苗均全部存活,且总生物量≥对照(未沙埋幼苗);当沙埋深度增至植株高度的66%时,1周龄和2周龄幼苗的存活率分别降至70%和25%,生长也受到抑制;而遭受全部沙埋时,1周龄和2周龄幼苗均不能存活.遭受沙埋后,无芒雀麦幼苗分配较多的生物量用于地上部分的生长,其生物量分配模式改变可能是无芒雀麦幼苗对沙埋环境的重要适应对策.     

补施CO2对日光温室黄瓜生长的影响

实验以日光温室中正常生长的黄瓜为对照,研究了补施CO2对温室黄瓜光合作用,株高、茎粗、节数、植株干重及鲜重,叶绿素含量、叶面积及厚度,瓜长、瓜重及周径,总产量和抗病性的影响.结果表明与生长正常条件下黄瓜的日光合曲线相比,补施CO2的温室内黄瓜的日光合曲线有所改变,日平均光合速率提高了1.275 μmol*m-2*s-1;与对照相比,株高、茎粗、节数、植株干重、鲜重分别增加了10.7%、37.6%、27.1%、27.3%、31.4%,对植株节数和干鲜重的影响达到极显著水平;叶绿素含量、叶面积及厚度分别增加了0.48%、7.07%、24.82%,对叶面积的影响达到显著水平;黄瓜的果长、果重和平均周径分别增加了9.4%、13.1%、11.8%,对果重的影响达到显著水平;温室总体产量增加了23.96%;补施CO2也提高了黄瓜抗病性,使每百株的发病株次降低了9株次.补施CO2可以缩小黄瓜植株间差异.     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。