花粉——雌蕊相互作用的分子基础

显花植物授粉过程包含了花粉与雌蕊一系列复杂的细胞间相互作用。花粉在柱头上必须发生粘附与水合作用后才能萌发,花粉胞被蛋白可能在粘附机制中起主要作用,而水孔蛋白调节了花粉的水合过程;花粉管在花柱引导组织中定向生长,受引导组织胞间质、向化性物质及细胞粘附机制等因素的影响,也与花粉受体及子房有关。在植物的自交不亲和性反应中,配子体型自交不亲和性反应主要是由自交不亲和基因蛋白产物降解花粉RNA或以Ca^2 介导的信号级联反应实现的;孢子体型自交不亲和性反应则依赖于干性柱头以及雌蕊的S受体激酶及S位点糖蛋白与花粉S基因配体之间的相互作用。     

拟南芥花粉细胞质游离钙离子荧光测定法

以拟南芥花粉为材料,利用低温装载法在完整的花粉粒中,成功地载入酯化形式的钙离子荧光探针Fura-2/AM。利用荧光比率分析法对花粉细胞质中游离钙离子的分布特点进行研究并测定了花粉细胞内游离钙离子浓度。结果表明花粉萌发初期细胞质内游离钙离子呈极性分布,萌发沟附近的钙离子浓度明显高于其它部位,萌发孔附近最高,花粉细胞核中最低。花粉粒细胞萌发状态下的[Ca2 ]i=246±38nmol/L,该值与花粉粒细胞萌发状态下游离钙离子浓度用其它方法测得值接近,进一步表明所建立的用Fura-2/AM检测拟南芥花粉粒细胞质游离钙离子的方法是可靠的。     

钙和硼对蓝猪耳花粉萌发及花粉管生长的影响

研究了钙(Ca^2 )和硼(H3BO3)对蓝猪耳花粉萌发和花粉管生长的影响。结果表明：(1)在一定范围内Ca^2 几乎不影响花粉萌发频率,而主要影响花粉萌发速度和花粉管生长速度;低Ca^2 不利于花粉管生长,而高Ca^2 抑制花粉萌发速度和花粉管生长;在稍高于最适Ca^2 浓度的条件下,花粉管生长早期呈现波浪形。(2)硼明显影响花粉萌发频率及花粉管形态;花粉管生长必需硼,但不同浓度的硼对花粉管生长速度影响不明显;在高浓度硼条件下,较长时间内花粉管均呈现出波浪形。(3)Cooled-CCD动态跟踪观察进一步证实Ca^2 影响花粉管生长速度,而硼则不明显。     

新牧Ⅰ号杂花苜蓿异交机制与自花粉的生殖干扰

通过控制试验和荧光观测等手段对新牧Ⅰ号杂花苜蓿Medicago varia Martyn'Xinmu No.1'柱头可授期与最佳授粉时间、自花粉的堵塞效应、花粉萌发与花粉管生长状况等进行研究,结果显示:(1)苜蓿柱头可授期与单花寿命具高度的同步性,在单花开放的第1天授粉,传粉效率最高,结果率达65.170%±2.01%(P<0.01),为柱头的最佳授粉时期;在单花开放后第4天授粉,其结果率仍达34.25%±6.73%.(2)自花授粉比异花授粉有着较低的花粉萌发率和花粉管生长速度;清除柱头自花粉后再授异花粉,其结荚率/花序和英内种子粒数由原来的51.760%±5.37%和2.11±0.18粒,提高到72.31%±6.24%(P<0.01)和3.46±0.25粒(P<0.01),自花粉对柱头的堵塞效应非常明显.(3)在繁育系统中,苜蓿采取了雌雄异熟和自交不亲和两套机制来避免自交,但是由于其独特的花结构,即使雄蕊先熟,在保证苜蓿异交机制中也没有起到有效的作用,而其典型的自交不亲和系统,虽然保证了苜蓿较低的自交率,却无法避免自花粉的生殖干扰.     

细胞松弛素B和鬼笔环肽对梨花粉萌发和花粉管生长的影响

以砂梨(Pyrus pyrifoliaNakai)品种今村秋(Imamuraaki)和丰水(Hosui)为材料,分别用光学显微镜和荧光显微镜观察了离体和半活体条件下微丝骨架解聚剂细胞松弛素B(cytochalasin B,CB)和稳定剂鬼笔环肽(phalloidin)对梨花粉萌发和花粉管生长的影响.结果表明:(1)低浓度(10μg/mL)鬼笔环肽能促进花粉萌发和花粉管生长,但高浓度对花粉萌发和花粉管的生长具有抑制作用;CB抑制花粉萌发和花粉管生长,且抑制效应随其浓度的增加而增强.(2)鬼笔环肽处理柱头后进行自花授粉,可明显促进自花花粉萌发和花粉管的生长,而CB处理柱头后异花授粉则抑制异花花粉萌发及其花粉管生长.可见,微丝骨架参与了梨花粉萌发和花粉管生长过程,并参与了梨自交不亲和反应的调节.     

‘晚大新高’梨授粉及受精过程的显微动态研究

应用荧光显微法和石蜡切片解剖法对‘晚大新高’梨授粉受精过程进行了系统观察研究。结果表明：‘晚大新高’梨自花授粉不结实;异花最佳授粉品种为‘黄花’,其次为‘翠冠’和‘丰水’。与选用‘黄花’为异花授粉品种相比,自花和异花的授粉受精过程存在明显差异,自花花粉在授粉后2h开始萌发,8h花粉管生长至离柱头约1／3处停止生长,顶端膨大呈球形,表现出自交不亲和性;异花花粉在授粉后1h开始部分萌发,8h花粉管生长至花柱中部,24h到达花柱基部并进入子房,48h进入胚囊,72h完成双受精过程。     

G蛋白调节剂对梨花粉萌发及花粉胞内Ca2+浓度变化的影响

用激光共聚焦技术研究了异三聚体G蛋白活性调节剂对梨花粉萌发、花粉管生长及花粉细胞内游离钙离子浓度动态的影响。结果表明：异三聚体G蛋白激活剂霍乱毒素(CTX)可促进梨花粉萌发与花粉管生长,而其抑制剂百日咳毒素(PTX)则抑制花粉萌发与花粉管生长;霍乱毒素处理后,花粉细胞内产生特异性的“钙瞬变”信号,而百日咳毒素处理后则引起花粉细胞内游离钙离子浓度的持续下降。这表明：异三聚体G蛋白可能参与了梨花粉萌发与花粉管生长的调控过程,G蛋白的活性变化对花粉萌发的效应可能是通过调控花粉细胞内游离Ca^2 浓度的动态变化产生特异性的钙信号来实现的。     

青篱柴通过促进亲和花粉生长而提高传粉精确性

异型花柱植物的适应意义在于提高亲和花粉的传递, 从而促进异交, 但是有不少研究发现柱头上落置了大量不亲和花粉。目前, 很少有人研究柱头是否有利于亲和花粉的萌发和花粉管伸长, 以及通过去雄处理排除花内和植株内不亲和花粉干扰从而验证二型花柱植物是否可以促进异交。本研究以亚麻科青篱柴属(Tirpitzia)的二型花柱植物青篱柴(T. sinensis)为研究对象, 分居群调查了青篱柴长、短柱型的植株数量, 测量不同柱型的花粉与柱头大小以及观察其表面纹饰, 测定不同开花时间长、短柱型的柱头活性与花粉活力, 统计自然状态下柱头上落置的不同表型花粉比例, 进一步统计花内、株内去雄和自然对照下柱头上落置的不同表型花粉比例, 计算型间、型内和混合授粉花粉管长度和花粉萌发率, 人工授粉检测其是否型内异交不亲和与自交不亲和。结果表明, 自然居群中长、短柱型青篱柴植株数量没有显著性差异; 短柱型青篱柴花粉体积显著大于长柱型, 且二者花粉表面纹饰不同, 但不同柱型的柱头表面积与表面纹饰无差异; 青篱柴开花第一天的花粉活力显著高于开花第二天, 而柱头活性在开花前两天无显著性差异; 自然状态下柱头上落置的不亲和花粉比例显著高于亲和花粉; 在长柱型青篱柴中, 花内和株内去雄显著提高了柱头上亲和花粉的落置比例; 柱头上授型内花粉, 其花粉萌发率和花粉管的长度都显著低于授型间花粉; 授粉结果表明青篱柴为型内异交不亲和与自交不亲和。二型花柱植物通过促进亲和花粉的萌发和花粉管的伸长而有利于型间授粉, 从而显著提高其传粉精确性。     

新牧I号杂花苜蓿异交机制与自花粉的生殖干扰

通过控制试验和荧光观测等手段对新牧I号杂花苜蓿Medicago varia Martyn‘XinmuNo.1＇柱头可授期与最佳授粉时间、自花粉的堵塞效应、花粉萌发与花粉管生长状况等进行研究,结果显示：（1）苜蓿柱头可授期与单花寿命具高度的同步性,在单花开放的第1天授粉,传粉效率最高,结荚率达65.17%&#177;2.01%（P〈0.01）,为柱头的最佳授粉时期;在单花开放后第4天授粉,其结荚率仍达34.25%&#177;6.73%。（2）自花授粉比异花授粉有着较低的花粉萌发率和花粉管生长速度;清除柱头自花粉后再授异花粉,其结荚率/花序和荚内种子粒数由原来的51.76%&#177;5.37%和2.11&#177;0.18粒,提高到72.31%&#177;6.24%（P〈0.01）和3.46&#177;0.25粒（P〈0.01）,自花粉对柱头的堵塞效应非常明显。（3）在繁育系统中,苜蓿采取了雌雄异熟和自交不亲和两套机制来避免自交,但是由于其独特的花结构,即使雄蕊先熟,在保证苜蓿异交机制中也没有起到有效的作用,而其典型的自交不亲和系统,虽然保证了苜蓿较低的自交率,却无法避免自花粉的生殖干扰。     

百合花粉细胞中钙离子的荧光测定法1

以川百合花粉为材料,利用孵育法在花粉原生质体中,特别是利用低温装载法在完整花粉粒中,成功地载入酯化形式的钙离子荧光探针fluo-3AM.利用激光共聚焦显微技术对花粉细胞质中游离钙离子的分布特点进行研究的结果表明,花粉萌发初期细胞质内游离钙离子呈极性分布,萌发沟附近的钙离子浓度明显高于其他部位,萌发孔附近最高,花粉细胞核中较低.文中对低温装载法的可行性进行了讨论.     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

2017年中国植物科学若干领域重要研究进展

2017年中国植物科学继续保持高速发展态势, 重大成果频出, 具体表现在中国植物学家在国际顶级学术期刊发表的文章数量平稳上升。中国植物科学领域的研究工作者成果精彩纷呈, 如新型广谱抗病机制的发现、水稻广谱抗病遗传基础及机制和疫霉菌诱发病害成灾机制研究等。2017年中国生命科学领域十大进展评选中, 有两项植物科学领域的研究成果入选。水稻生物学、进化与基因组学和激素生物学等领域学科发展突出。另外, 值得一提的是, 长期从事高等植物与代谢途径调控分子网络研究和水稻品种设计育种的李家洋院士的研究成果“水稻高产优质性状形成的分子机理及品种设计”荣获2017年国家自然科学一等奖。这一具有重大国际影响的开创性贡献标志着中国植物科学在该领域的国际科学前沿居于引领和卓越地位。该文对2017年中国本土科学家在植物科学若干领域取得的重要研究成果进行了系统梳理, 旨在全面追踪和报道当前中国植物科学领域发展的最新前沿动态, 与广大读者共同分享我国科学家所取得的辉煌成就。     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

Changes in aquatic vegetation in Rhine floodplain streams in Alsace in relation to disturbance

Abstract. Changes are described in aquatic vegetation in oligotrophic, groundwater-fed Rhine floodplain streams in Alsace (eastern France), resulting from disturbance. Disturbance factors include changes in nutrients, either permanent ones - effluent from a waste water treatment plant or trout hatcheries - or periodic ones: flooding. Regular inputs of high levels of phosphate and ammonia modified the macrophyte vegetation in these streams. The floristic composition, which was characteristic of oligotrophic waters upstream of the eutrophicated sector, changed to that of a eutrophic situation as originally found downstream. Periodic disturbance by floods which normally occur once a year, irregularly eutrophicates the small streams, causing the development of a mixture of eutrophic and oligotrophic species. Six macrophyte communities are distinguished, indicating different trophic levels. The aquatic vegetation is adapted to the variations of phosphate and ammonia levels. Hence, aquatic macrophytes can be used as bio-indicators of fluctuations in water nutrient levels in relation to the type of disturbance.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.     

Peroxisomes in Rice Coleoptiles Grown in Air and in Anoxia

Rice coleoptiles grow under anoxia. When the ultrastructure of anoxic coleoptile cells was examined, it was seen that most organelles maintain their integrity, with the exception of peroxisomes (unspecialized type). The lack of O₂ greatly reduced the number of these organelles and altered the ultrastructure of the remaining ones. To examine the effect of O₂ on peroxisome development in more detail, coleoptiles grown in air were transferred to N₂ and anoxic coleoptiles were transferred to oxygen. Marker enzyme activity was measured in entire coleoptiles as well as in the isolated organelles. As expected, anoxia greatly depressed enzyme activity when imposed from the beginning of the germination process, while it had a lesser effect when imposed for only two days on aerobic seedlings. When coleoptiles were grown constantly under N₂, the density of the organelles was 1.216 g/cm³, while the corresponding aerobic organelles showed a buoyant density of 1.241 g/cm³. When transferred to air the anoxic peroxisomes reached the intermediate density of 1.227 g/cm³. The results confirm the particular sensitivity of rice peroxisomes to O₂ availability.