遮荫和干旱复合处理对黄藤幼苗个体生长及生理特性的影响

以1年生黄藤(Daemonorops jenkinsiana)实生苗为试验材料,采用盆栽控制试验测定分析遮荫和干旱复合处理下黄藤幼苗的生长状况、叶片光合参数、生物量及生理特征的变化情况,以阐明遮荫和干旱复合处理对其生长和生理的影响规律。结果显示：(1)黄藤的株高、地径和功能叶片数目均随遮荫度上升而增加;植株叶片的生物量、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)均随遮荫度上升而呈先上升后下降的趋势。(2)黄藤叶片的可溶性蛋白(SP)、脯氨酸(Pro)随着遮荫度的增加而先增加后下降,丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)活性则均呈先下降后上升的趋势。(3)中度遮荫时,黄藤的株高、地径、功能叶数目、叶片生物量的积累以及P_n、T_r、WUE、Pro和SP含量均显著升高(P＜0.05),SOD活性和MDA含量则显著降低(P＜0.05)。(4)干旱胁迫导致黄藤的株高、地径、功能叶片数目、叶片生物量积累、P_n、T_r、WUE显著降低,SOD活性、POD活性、MDA含量和Pro含量均显著升高。研究发现,遮荫和干旱复合作用影响黄藤幼苗的生长和发育。黄藤幼苗能通过调整生长策略、光合策略、代谢策略等使植株逐步适应或耐受胁迫,表现出一定的抗旱性和喜阴性;中度遮荫(遮光20%~30%)能够改善黄藤幼苗的生境,并能缓解干旱胁迫对植株造成的伤害,对其生长有利。     

麻栎和闽楠幼苗叶功能性状及生物量对光照和施肥的响应

光照和养分条件是影响植物生长的重要环境因子,不同生活型植物对环境异质性的响应机制不同。以落叶阔叶树种麻栎和常绿阔叶树种闽楠幼苗为研究对象,设置2个光照梯度（全光照和45%全光照）和4个施肥梯度（不施肥、氮磷供应比为5、15和45）共8种处理,研究光照和施肥及其交互作用对麻栎和闽楠生物量和叶形态、生理及化学性状的影响,并探讨了叶功能性状和生物量的关系。结果表明：（1）光照、施肥及其交互作用对光合气体交换参数（除水分利用效率外）、叶绿素荧光参数、叶形态指标（除比叶面积外）、单位质量叶氮含量和根冠比影响显著（P<0.05）。此外,光照和施肥对地上生物量和总生物量影响显著（P<0.05）。（2）全光照显著增加了麻栎和闽楠单株总叶面积和地上、地下生物量及总生物量（P<0.05）,而遮荫降低了非光化学猝灭系数、光合氮利用率和根冠比,增加了单位质量叶氮含量。（3）在全光照处理中,施肥显著增加了麻栎和闽楠水分利用效率（P<0.05）;在遮荫处理中,氮磷供应比45显著增加了麻栎和闽楠净光合速率和水分利用效率（P<0.05）。（4）麻栎和闽楠在全光照中倾向于资源获取策略,在遮荫中偏向于资源保守策略。在光照和施肥处理中,麻栎和闽楠单株总叶面积与地上生物量均显著正相关（P<0.05）。总之,单株总叶面积是预测麻栎和闽楠幼苗地上生物量变化的稳定指标,施肥有助于增加低光环境下麻栎和闽楠幼苗的生态适应能力。     

遮阴和施氮对黄檗幼苗叶片光合特性和碳氮计量特征的影响

选取大田环境下3年生黄檗幼苗,采用人工控制双因素随机区组试验,在不同光照［全光照(S₀)、轻度遮光21.4%(S₁)和重度遮光8.7%(S₂)］和不同氮添加［无添加对照(F₀)、轻度添加(F₁)和重度添加(F₂)］条件下,测定黄檗幼苗叶片的相对叶绿素含量(SPAD值)、气体交换参数及碳氮化学计量特征,探讨黄檗幼苗对遮阴和施氮的响应机制。结果表明：(1)随着遮光程度增强,黄檗幼苗叶片的SPAD值、蒸腾速率(T_r)、气孔导度(G_s)、碳氮比(C∶N)和瞬时光合氮利用率(PNUE)均呈现先增后降的趋势,两种遮光条件下SPAD均显著高于全光照环境;黄檗幼苗叶片的净光合速率(P_n)、水分利用率(WUE)和气孔限制值(L_s)逐渐降低;而叶片氮(N)和碳(C)含量均呈先降后升的趋势。(2)随氮添加量增加,黄檗幼苗叶片的P_n、WUE、L_s、N和C含量均呈先增后降趋势,T_r、G_s和PNUE则逐渐下降,而C∶N逐渐增加。(3)黄檗幼苗叶片的P_n在各光氮组合处理间均无显著差异;SPAD含量以S₁F₀、S₂F₀和S₁F₂处理组合显著较高,而以全光照(S₀)处理组合显著最低;T_r和G_s以轻度遮光(S₁)处理组合明显较高,而以S₂F₁、S₀F₂、S₂F₂明显较低;WUE和L_s均以S₀F₂显著最高,S₂F₂处理组合显著最低。黄檗幼苗叶片N和C含量在重度遮光/轻度氮添加(S₂F₁)时具有较大值,而其C∶N和PNUE在轻度遮光/无氮添加(S₁F₀)时具有较大值。(4)隶属函数综合评价认为,黄檗幼苗对光氮复合作用总体属中等耐受型,轻度遮光时不添加氮肥(S₁F₀)和轻度氮添加(S₁F₁)及全光照时轻度氮添加(S₀F₁)为适于幼苗生长的光氮组合。研究发现,光环境是影响黄檗幼苗光合作用和更新的主导因子,但黄檗苗期能耐受一定的遮阴胁迫;光照不受限制时,适当增加氮肥有利于黄檗幼苗生长;光照受限(重度遮光)时,施氮则抑制叶片叶绿素合成,降低了幼苗光能利用率,不利于其生长。     

遮光对连香树幼苗光合特性及其叶片解剖结构的影响

以2年生连香树实生苗为材料,在田间通过黑色遮阳网设置全光照(L₀)及透光率55%(L₁)、25%(L₂)和10%(L₃)4种光环境,研究遮光对连香树幼苗光合作用及叶片解剖结构的影响。结果表明：(1)连香树幼苗叶片P_n在全光和L₁处理下呈非典型的“乁”形变化,未出现“午休”现象,中午14:00出现极值,而在L₂和L₃处理下变化相对缓和,极值出现在中午12:00;叶片G_s呈现与P_n类似的变化趋势,而C_i则呈基本一致的凹形变化。(2)各处理P_n、G_s和T_r的日均值均表现为L₀＞L₁＞L₂＞L₃,而C_i的日均值则呈相反的顺序;P_n与G_s、T_r、气温和光合有效辐射均呈极显著正相关关系(P＜0.01)。(3)全光照连香树幼苗的光补偿点(LCP)、光饱和点(LSP)、暗呼吸速率(R_d)均显著高于遮光处理,并维持较高的P_n而未出现明显的光抑制;遮光导致幼苗的LCP、LSP、R_d显著降低,有利于充分利用弱光,以满足低光环境下植株的正常生长。(4)与全光照相比,遮光下连香树叶片气孔密度显著变小,但气孔器长度、气孔器宽度、单个气孔器面积显著增加,气孔器面积百分比减少,影响幼苗细胞内外的水分和气体传递。(5)遮光条件下,连香树叶片明显变薄,表皮细胞厚度减小,栅栏组织(PT)厚度降低,排列变得疏松,海绵组织(ST)厚度增加,PT/ST相应减小。(6)与全光照相比,强度遮光下(L₂和L₃)连香树幼苗生长受阻,苗高(H)和基径(D)明显减小,生物量模型D²H下降;而轻度遮光(L₁)下幼苗H和D、H/D和D₂H均未出现显著变化。研究发现,连香树具有一定的光忍耐性和喜光性,对光照条件的生态幅较宽,轻度遮光影响较小,但强度遮光对连香树幼苗气体交换参数和光合响应特征产生了显著影响,同时影响了叶片的解剖结构和气孔分布特征,从而影响连香树幼苗的生长形态。在育苗生产中,适度遮光有利于降低气温、减小蒸腾,但遮光后田间有效辐射强度应保持在自然光强的55%以上。     

低钾胁迫对谷子幼苗叶片光合作用的影响

为了探究低钾胁迫引起谷子幼苗光合作用改变的响应机制,以谷子品种‘晋谷21号’(钾敏感型)和 ‘龙谷25号’(钾非敏感型)为试验材料,设置正常供钾(5.0 mmol·L^-1, K₅)、低钾(1、0.1、0.01 mmol·L^-1, K₁、K_0.1、K_0.01)和无钾(0 mmol·L^-1,K₀)5个处理,通过营养液盆栽实验,分析不同程度低钾胁迫对谷子幼苗生长、光合气体交换参数、叶绿素荧光特性和碳同化关键酶活性的影响。结果表明：(1)低钾胁迫显著抑制了谷子幼苗的生长,株高、茎粗、叶面积及干物质显著降低,同时叶片钾含量减少,K₀处理‘晋谷21号’和‘龙谷25号’叶片钾含量较K₅处理分别显著降低了48.14%和37.85%。(2)K₀处理谷子幼苗光合色素含量较K₅处理显著降低,但K_0.1和K₁处理与K₅处理差异不显著。(3)低钾胁迫导致谷子幼苗叶片净光合速率(P_n)降低,与K₅处理相比,K₀、K_0.01、K_0.1处理P_n、气孔导度(G_s)、蒸腾速率(T_r)、气孔限制值(L_s)显著降低,胞间CO₂浓度(C_i)却显著增加,证明光合速率降低主要由非气孔限制引起。(4)低钾胁迫很易导致光系统Ⅱ(PSⅡ)和光系统Ⅰ(PSⅠ)光化学量子产量降低,K₁处理叶片的PSⅡ实际光化学量子效率(Φ_PSⅡ)、PSⅠ光化学量子产量［Y(Ⅰ)］分别降低了5.32%~9.57%和2.38%~5.63%,K₀处理则分别显著降低了17.15%~20.15%和18.71%~21.28%。(5)K₀处理下‘晋谷21号’的 1,5 二磷酸核酮糖羧化酶(Rubisco)和磷酸烯醇式丙酮酸羧化酶(PEPC)活性较K₅处理分别显著降低了42.86%和42.71%,相应处理的‘龙谷25号’则分别显著降低了26.85%和42.77%。研究发现,低钾胁迫下‘龙谷25号’对钾素吸收利用能力较强,各生长生理参数变化幅度较小,表现出较强的低钾耐性;低钾胁迫导致谷子幼苗净光合速率降低,K₀和K_0.1处理下光合速率降低主要与气孔导度降低、光系统的电子传递与能量转换抑制以及碳同化关键酶Rubisco、PEPC活性下降等有关。     

基于叶绿体基因组数据的芸香科属间系统发育初步分析（专题约稿）

该研究在人工控制水分条件下,设置3个干旱胁迫处理,选用3个主栽油菜品种‘陇油10号’、‘陇油2号’、‘青杂5号’幼苗进行盆栽试验,测定干旱胁迫条件下叶片相对含水量、叶绿素含量、光合气体交换参数及叶绿素荧光参数等指标,考察各指标在干旱胁迫过程中的变化特征,并通过主成分分析(PCA)和隶属函数法评价品种的抗旱性及其主要响应因子,以揭示西北地区油菜幼苗响应干旱胁迫的光合调控机制。结果表明：(1)各品种油菜幼苗的叶片相对含水量(RWC)均随干旱胁迫程度的递增而逐渐降低,最大水分亏缺(WSD)却逐渐上升。(2)各品种油菜幼苗叶片的叶绿素a含量、叶绿素总含量随着干旱胁迫程度的递增而先增加后递减,且同一种幼苗在不同处理间差异显著。(3)各品种油菜幼苗叶片的净光合速率(P_n)、水分利用效率(WUE)、单株生物量、气孔导度(G_s)、胞间CO₂浓度(C_i)均在受到干旱胁迫时迅速降低,且同一品种幼苗在不同处理间差异显著,而其叶片蒸腾速率(T_r)在干旱胁迫下无显著变化。(4)各品种油菜幼苗叶片光化学猝灭系数(qP)和非光化学猝灭系数(NPQ)随着干旱胁迫程度的递增先增加后递减,最大光化学效率(F_v/F_m)和电子传递速率(ETR)在受到干旱胁迫时迅速降低,且同一品种幼苗在不同处理间差异显著。(5)主成分分析结果表明,在油菜幼苗受到干旱胁迫时RWC、C_i、G_s、P_n、WUE、叶绿素总含量、叶绿素a含量和NPQ起主要调控作用;隶属函数法综合评价表明,3个品种油菜幼苗耐旱能力由高到低依次为‘陇油10号’＞‘陇油2号’＞‘青杂5号’。     

香樟凋落叶分解过程对两种间作作物生长和光合特性的影响

采用盆栽试验方法,探讨了香樟(Cinnamomum camphora)凋落叶不同土壤添加水平(0 g/盆为CK、25 g/盆、50 g/盆,100 g/盆)对受体作物小白菜(Brassica chinensis)、莴笋(Lactuca sativa)幼苗生长和光合特性的影响。结果显示:(1)香樟凋落叶分解对两种作物的地径、株高、生物量、叶片数和叶面积均有明显的抑制作用,且抑制效应随凋落叶添加量的增加而增强,但随着分解时间的延长其抑制作用逐渐减弱甚至表现为促进作用。(2)香樟凋落叶分解对两种作物的光合色素含量均有明显的抑制效应,并随凋落叶添加量的增加抑制作用增强,且持续时间延长。(3)经凋落叶处理的两种作物叶片净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、水分利用率(WUE)总体上均低于CK,而胞间CO₂浓度(C_i)在各凋落叶处理下均高于CK。(4)随着土壤中凋落叶量的增加,两种作物在光饱和以及CO₂饱和状态下的最大净光合速率(P_{n max})、表观量子效率(AQY)、羧化速率(CE)、光呼吸速率(R_p)和暗呼吸速率(R_d)均不断下降,而光补偿点(LCP)、光饱和点(LSP)、CO₂饱和点(CSP)、CO₂补偿点(CCP)因受体作物的不同,表现出不同的变化趋势。研究表明,土壤中香樟凋落叶分解释放的化感物质,能通过降低受体作物的光合色素合成和光合能力,限制其营养生长,最终影响生物量积累;相对于莴笋,小白菜对香樟凋落叶分解产生的化感胁迫效应具有更强的耐受性,可能更适宜在香樟林间种植。     

干旱胁迫下喷施黄腐酸对燕麦光合及其抗氧化酶活性的影响

为了揭示黄腐酸对干旱胁迫下燕麦光合及其抗氧化酶活性的影响机理,该研究选用燕麦品种‘燕科2号’为材料,采用盆栽试验,以正常供水(田间持水量的75%)为对照(CK),设干旱胁迫处理(田间持水量的45%,D0)、D0 + 喷施不同浓度黄腐酸(0、200、400、600、800、1 000 mg/L)处理(D1~D5),测定各处理燕麦干鲜重、光合性能及其抗氧化酶活性。结果表明:(1)与CK相比,干旱胁迫下燕麦幼苗地上部鲜重和干重、叶片光合色素含量、净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)均显著降低,并导致叶片F_v/F_m、qP、ETR和Φ_PSⅡ显著下降,使叶片抗氧化酶 SOD、POD、CAT活性分别显著提高25.68%、19.98%和7.29%。(2)与D0相比,D0 +喷施600 mg/L黄腐酸后,燕麦幼苗地上部鲜重和干重分别显著提高了28.59%和39.13%,叶片叶绿素a、叶绿素a+b、类胡萝卜素和P_n、G_s、T_r及F_v/F_m、Φ_PSⅡ、ETR分别显著增加了25.17%、21.03%、47.37%和74.38%、26.47%、43.34%及6.49%、69.57%、70.71%,C_i和F_o、NPQ分别显著降低了19.52%和13.32%、43.75%。(3)干旱胁迫下喷施不同浓度的黄腐酸均使幼苗叶片中SOD、POD、CAT活性较D0处理显著增加,其中喷施600 mg/L黄腐酸的叶片SOD、POD、CAT活性最高,分别较D0处理显著增加了12.19%、76.57%和55.26%。研究认为,叶面喷施适宜浓度黄腐酸能够显著提高干旱胁迫下燕麦幼苗的光合作用及其抗氧化能力,缓解干旱对燕麦幼苗的伤害,进而促进燕麦幼苗的生长,且以叶面喷施600 mg/L黄腐酸效果最佳。     

水分胁迫对极小种群东兴金花茶幼苗光合特性的影响

为了解东兴金花茶幼苗对水分胁迫的适应能力和响应机制,该文以东兴金花茶1年生实生苗为材料,采用盆栽控水试验,研究不同控水时间处理对东兴金花茶幼苗的生理生态特性的影响。结果表明:随着控水时间的延长,水分胁迫的程度不断加剧,东兴金花茶叶片净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)呈现显著下降趋势; 胞间CO₂浓度(C_i)呈现先低后高的变化趋势,水分利用效率(WUE)呈现先高后低的变化趋势。土壤含水率和叶片相对含水量均呈现不断下降的趋势,丙二醛呈现先降后升的变化趋势; 东兴金花茶幼苗的荧光参数F_v/F_m和F_v/F_o呈现先增加后不断下降趋势,分别从0.806下降至0.754和4.17下降至3.08,表明水分胁迫降低了PS Ⅱ原初光能转化效率,光合作用原初反应过程受到抑制。基于水分胁迫的生理生态指标和叶片生物性状的变化表明,控水时间在4 d情况下东兴金花茶可以提高自身水分利用效率来抵抗干旱,说明东兴金花茶幼苗对水分胁迫具有一定的适应性和响应机制。控水8～12 d,东兴金花茶的光合指标下降显著,土壤含水率下降至14.157%～15.065%,其叶片萎蔫、打卷,低于此水平东兴金花茶幼苗会因过度干旱而死亡,表明东兴金花茶幼苗对水分胁迫的耐受极限土壤含水率为14.157%～15.065%。研究结果有助于营建适宜的环境以保证东兴金花茶的正常生长和繁殖,对东兴金花茶迁地保护、引种培育和回归自然具有重要的科学指导意义。     

外源H2O2对盐碱胁迫下苹果矮化砧木幼苗生理特性的影响

以2年生苹果矮化砧木M9 T337为试材,采用盆栽试验法,设置浇灌清水(CK)和盐碱胁迫(0.1 mol/L NaCl+NaHCO₃溶液)+ 喷施5种浓度的H₂O₂ ［0(T₁)、0.2 mmol/L(T₂)、0.4 mmol/L(T₃)、0.6 mmol/L(T₄)、0.8 mmol/L(T₅)］ 处理,测定各处理叶片叶绿素含量、光合气体交换参数、渗透调节物质含量、抗氧化酶活性和细胞膜透性,并利用相关性与主成分分析进行综合评价,以探讨外源过氧化氢(H₂O₂)增强其盐碱耐性的生理机制。结果表明：(1)随着盐碱胁迫(T₁)的时间延长,M9 T337幼苗叶片叶绿素a(Chl a)含量、叶绿素b (Chl b)含量、叶绿素总量(Chl t)、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、可溶性蛋白(SP)含量均呈逐渐下降趋势;胞间CO₂浓度(C_i)、可溶性总糖(TSS)含量、脯氨酸(Pro)含量、过氧化氢酶(CAT)活性、抗坏血酸过氧化物酶(APX)活性、相对电导率(REC)、丙二醛(MDA)含量均呈上升趋势;超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性均呈先升后降趋势。(2)与CK相比,盐碱胁迫+外源H₂O₂(T₂- T₅)处理后M9 T337幼苗叶片各指标均呈现不同幅度变化,且存在明显浓度效应,并以T₃(0.4 mmol/L H₂O₂)处理叶片的Chl a、Chl b、Chl t、SP和G_s降幅最小,C_i、REC、MDA升幅最小,TSS、Pro、APX升幅最大。(3)M9 T337幼苗叶片P_n与T_r、G_s、Chl a、Chl b、Chl t、SP、SOD、POD呈显著正相关,与C_i、MDA、CAT、APX、REC呈显著负相关。(4)综合评价表明,各处理对M9 T337幼苗叶片生理特性的效应依次为：CK>T₃>T₄>T₂>T₅>T₁。研究发现,叶面喷施适宜浓度H₂O₂可有效改善盐碱胁迫下M9 T337幼苗光合能力,显著提高抗氧化酶活性和渗透调节物质的含量,降低细胞膜透性,从而达到缓解盐碱胁迫的作用,并以0.4 mmol/L H₂O₂处理效果最佳。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

广西青藓科分类学修订

通过对采自广西24个县(市)的1 147份青藓科植物标本的逐一鉴定及相关文献的查阅,确认有广西青藓科植物11属、44种,其中包括广西青藓科植物新记录属1属,即拟异叶藓属(Pseudokindbergia),新记录种7种,分别为匐枝青藓(Brachythecium procumbens)、阔叶尖喙藓(Oxyrrhynchium latifolium)、泛生尖喙藓(O. vagans)、拟异叶藓(Pseudokindbergia dumosa)、华东细喙藓(Rhynchostegiella sinensis)、长肋拟青藓(Sciurohypnum populeum)和弯叶拟青藓(S. reflexum)。该文提供了修订后的广西青藓科植物名录,并对其中的新记录属、种的主要形态学识别特征、生境和地理分布等进行了详细描述。     

The effect of cyanobacteria and azolla on the performance of rice under different levels of fertilizer nitrogen

Cyanobacteria and/or azolla were inoculated, with urea at 0, 72 or 144 kg N/ha, in plots in which azolla-free Indica rice var. IR 28 was grown. Productive tillers, yield and nitrogen contents of grain and straw positively responded to inoculation with cyanobacteria or azolla, even with fertilizer-N up to 144 kg N/ha. Inoculation improved colonization by cyanobacteria. Azolla were superior to the asymbiotic cyanobacteria in enhancing rice performance. Urea at a rate of 72 kg N/ha was found to support the best colonizations when applied with cyanobacteria or azolla or, to give maximum rice yields, both inoculants.     

Evaluation of antiprotozoal and antimycobacterial activities of the resin glycosides and the other metabolites of Scrophularia cryptophila

Resin glycosides are secondary metabolites exclusive to the convolvulaceous plants. In this study, crypthophilic acids A–C (1–3), the first resin glycosides occurring in another family (Scrophulariaceae), and the other constituents of Scrophularia cryptophila were examined for in vitro antiprotozoal and antimycobacterial potentials. Except for crypthophilic acid B (2), all tested compounds exhibited growth-inhibitory effect against Trypanosoma brucei rhodesiense, with l-tryptophan (6) and buddlejasaponin III (7) being the most potent ones (IC₅₀'s 4.1 and 9.7 μg/ml). In contrast, the activity towards Trypanosoma cruzi was poor, and only crypthophilic acid C (3), 6 and 7 were trypanocidal at concentrations above 40 μg/ml. With the exception of 2 and 6, all compounds were active against Leishmania donovani. Harpagide (4) and 3 emerged as the best leishmanicidal agents (IC₅₀'s 2.0 and 5.8 μg/ml). Only compounds 3, 6 and 7 showed antimalarial activity against Plasmodium falciparum with IC₅₀ values of 4.2, 16.6 and 22.4 μg/ml. Overall the best and broadest spectrum activity was presented by compounds 3 and 7, as they inhibited all four parasitic protozoa. None of the isolates had significant activity against Mycobacterium tuberculosis (MICs >100 μg/ml) or were toxic towards mammalian (L6) cells. This is the first report of antiprotozoal activity for natural resin glycosides, as well as for harpagide (4), acetylharpagide (5), tryptophan (6) and buddlejasaponin III (7).