23 resultados para desvio apical

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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A rare terrestrial species, Oedogonium pakistanense, was first recorded from Hubei Province, south-central China. Morphological characters. including the predominant occurrence of apical cell division and unique lateral apical caps, are described. The growth of the filaments in O. pakistanense from China is usually the result of the repeated divisions of the apical cells and intercalary divisions are rare. It is suggested that this species may represent an evolutionary transition between Oedogonium and Oedocladium, the latter being a terrestrial genus with branched filaments and cell division more often terminal than intercalary.

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Dynamic properties of proteins have crucial roles in understanding protein function and molecular mechanism within cells. In this paper, we combined total internal reflection fluorescence microscopy with oblique illumination fluorescence microscopy to observe directly the movement and localization of membrane-anchored green fluorescence proteins in living cells. Total internal reflect illumination allowed the observation of proteins in the cell membrane of living cells since the penetrate depth could be adjusted to about 80 nm, and oblique illumination allowed the observation of proteins both in the cytoplasm and apical membrane, which made this combination a promising tool to investigate the dynamics of proteins through the whole cell. Not only individual protein molecule tracks have been analyzed quantitatively but also cumulative probability distribution function analysis of ensemble trajectories has been done to reveal the mobility of proteins. Finally, single particle tracking has acted as a compensation for single molecule tracking. All the results exhibited green fluorescence protein dynamics within cytoplasm, on the membrane and from cytoplasm to plasma membrane.

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本实验用喷施6-BA和茎切生根的方法建立了一套德国鸢尾快速分株繁殖的体系。用3 000 mg/L 或5 000 mg/L 的6-BA 对德国鸢尾(Iris germanica)‘lovely again’进行单次喷施可以促进根茎芽的萌发和根状茎的形成。在喷施后的30 天到90 天内,BA的促进作用在具有2个或4个起始根状茎的植株上表现得很显著,但对于只有一个起始根状茎的植株不显著。在喷施后的150 天以及第二年,具有2个或4个起始根状茎的母株总体上比只具有1个起始根状茎的母株产生了更多的根状茎。而6-BA的喷施对母株的叶面积和叶片数变化没有显著影响。在早春时,把处于不同发育阶段的侧芽或小根茎从母株上取下,并且用不同浓度的IBA处理。总体上,处于较高发育阶段的茎切(芽切)在生根率、初级根和次级根的数目,总根长、根干重以及植株高度等测量指标方面的表现较好。IBA对德国鸢尾的茎切(芽切)的生根作用不显著。多次喷施6-BA 对德国鸢尾根茎芽的生出的促进作用显著,并且使生物量重新分配。连续喷施6-BA后,对内源生长素和细胞分裂素的连续测定结果表明,6-BA的作用主要是解除了顶端优势对侧芽的萌发和生长的抑制,从而形成新的根茎。

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植物的生境在时间和空间上都是异质性的,即使在很小的尺度上这种异质性也是存在的。克隆生长使得克隆植物在理论上更适应利用异质性环境,本文以几种克隆植物为对象,采用实验生态学方法,着重从生理生态特性、信号物质传导方面探讨克隆植物对异质性环境的适应对策。 以匍匐茎克隆植物野草莓(Fragaria vesca)为对象,研究了不同海拔梯度种群(1800m和3900m)对光照和养分资源斑块性分布生境的响应。研究结果显示:与资源的空间同质性处理(I) 和(II) 相比, 资源的空间异质性处理(III) 和(IV) 两个种群野草莓的近端、远端和整个克隆片段的生物量和分株数均获得显著增加。经历低光高养近端分株与经历高光低养的远段分株相连时,相比与低光高养的同质生境,来自两个海拔的种群分配更多的生物量到根;经历高光低养近端分株与经历低光高养远端分株相连时,相比于高光低养的同质生境,来自两个海拔的种群分配更少的生物量到根,类似的生物量分配格局在远端分株也被观察到。相比于高光低养同质性生境,当与低光高养远端分株相连时经历高光低养近端分株有更大的叶面积;相比于高光低养同质性生境,当与低光高养近端分株相连时经历高光低养远端分株有更大叶面积。实验结果表明, 资源交互斑块性生境中野草莓发生了克隆内分工。通过克隆内分工, 克隆植物能有效的利用异质性分布的资源, 缓解资源交互斑块性分布对克隆植物生长的不利影响。 以匍匐茎克隆植物蛇莓(Duchesnea indica)为对象, 研究其在高光照低水分斑块和低光照高水分斑块组成的资源交互斑块性生境中的克隆内分工。结果显示,当生长于高光照低水分(HL)条件下近端分株(basal ramets)与生长于低光照高水分(LH)条件下的远端分株(apical ramets)之间的匍匐茎连接时,近端分株根冠比显著下降,而远端分株根冠比显著增加,近端分株叶面积和远端分株总根长显著增加;当与低光照高水分条件下的远端分株相连时,近端分株叶片光合速率和叶绿素含量也相应增加。此外,克隆分株间资源交互传输显著提高蛇莓的生长表现(生物量和分株数)。因此,在光、水资源交互斑块性环境中克隆植物蛇莓分株在生物量分配、资源获取器官形态和生理特性方面发生了环境诱导的功能特化。这种对局部丰富资源的趋富特化在一定的程度上增强了克隆分株对资源的吸收利用能力,克隆内资源共享有助于缓解资源交互性斑块生境对克隆植物生长的不利影响,有效地提高克隆植物在其生境中存活与定居能力。 一个盆栽实验被采用以便调查克隆整合对经受局部沙埋的根状茎克隆植物沙生苔草(Carex praeclara)的影响,结果显示随着沙埋深度的增加,切断分株间的根状茎连接将显著降低经受沙埋处理分株的存活。当克隆植物经历局部沙埋时,切断分株间根状茎连接对其克隆生长(生物量、分株数和叶片数量)有显著负影响。耗-益(cost-benefit)分析显示,当与经历沙埋处理的远端分株相连时,近端分株的生长表现没有遭受任何负面影响。与经历沙埋处理远端分株相连时,近端分株的光合能力随沙埋深度的增加而增加。分株间的源-汇反馈调节机制所导致的补偿性反应减缓了局部沙埋对克隆植物生长的负效应。因此,克隆整合有助于提高经历局部沙埋克隆植物的存活,克隆植物在沙化地区植被恢复与重建方面具有重要意义。 克隆植物分株间的匍匐茎或根状茎连接不仅可以传输水分、矿质养分、光合产物,而且还可以传输信号物质。以根状茎克隆植物黑褐苔草(Carex alrofusca)为对象,采用盆栽实验研究外源茉莉酸诱导克隆片段相连分株间信号物质传导。结果显示,相比中龄和老龄分株,幼年分株对1mM茉莉酸诱导有显著反应。茉莉酸引起幼年分株叶片浓缩单宁含量显著增加,同时其叶片可溶性碳水化合物和氮含量降低。茉莉酸诱导后,幼年分株被昆虫咬食叶面积比率显著下降。因此匍匐茎或根状茎传也是克隆植物分株间信号物质传导重要通道,克隆植物通过分株间的风险扩散策略增强了对幼嫩植物组织器官的保护,这对克隆植物的存活或生长具有重要意义。

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Anterior gradient 2 (Agr2) genes encode secretory proteins, and play significant roles in anterior-posterior patterning and tumor metastasis. Agr2 transcripts were shown to display quite diverse tissue distribution in different species, and little was known about the cellular localization of Agr2 proteins. In this study, we identified an Agr2 homologue from gibe[ carp (Carassius auratus gibelio), and revealed the expression patterns and cellular localization during embryogenesis and in adult tissues. The full-length cDNA of CagAgr2 is 803 nucleotides (nt) with an open reading frame of 510 nt encoding 169 amino acids. The Agr2 C-terminus matches to the class I PDZ-interacting motif, suggesting that it might be a PDZ-binding protein. During embryogenesis, CagAgr2 was found to be transcribed in the mucus-secreting hatching gland from tailbud stage and later in the pharynx region, swim bladder and pronephric duct as revealed by RT-PCR and whole mount in situ hybridization. In the adult fish, its transcription was predominantly confined to the kidney, and lower transcription levels were also found in the intestine, ovary and gills. To further localize the Agr2 protein, the anti-CagAgr2 polyclonal antibody was produced and used for immunofluorescence observation. In agreement with mRNA expression data, the Agr2 protein was localized in the pronephric duct of 3dph larvae. In adult fish, Agr2 protein expression is confined to the renal collecting system with asymmetric distribution along the apical-basolateral axis. The data provided suggestive evidence that fish Agr2 might be involved in differentiation and secretory functions of kidney epithelium. (C) 2009 Elsevier Inc. All rights reserved.

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In an effort to develop cultured cell models for toxicity screening and environmental biomonitoring, we compared primary cultured gill epithelia and hepatocytes from freshwater tilapia (Oreochromis niloticus) to assess their sensitivity to AhR agonist toxicants. Epithelia were cultured on permeable supports (terephthalate membranes, "filters") and bathed on the apical with waterborne toxicants (pseudo in vivo asymmetrical culture conditions). Hepatocytes were cultured in multi-well plates and exposed to toxicants in culture medium. Cytochrome P4501A (measured as 7-Ethoxyresorufin-O-deethylase, EROD) was selected as a biomarker. For cultured gill epithelia, the integrity of the epithelia remained unchanged on exposure to model toxicants, such as 1,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), benzo(a)pyrene B[a]P, polychlorinated biphenyl (PCB) mixture (Aroclor 1254), and polybrominated diphenyl ether (PBDE) mixture (DE71). A good concentration-dependent response of EROD activity was clearly observed in both cultured gill epithelia and hepatocytes. The time-course response of EROD was measured as early as 3 h, and was maximal after 6 h of exposure to TCDD, B [alp and Aroclor 1254. The estimated 6 h EC50 for TCDD, B [a]P, and Aroclor 1254 was 1.2x10(-9), 5.7x10(-8) and 6.6x10(-6) M. For the cultured hepatocytes, time-course study showed that a significant induction of EROD took place at 18 h, and the maximal induction of EROD was observed at 24 h after exposure. The estimated 24 It EC50 for TCDD, B[a]P, and Aroclor 1254 was 1.4x10(-9), 8.1x10(-8) and 7.3x10(-6) M. There was no induction or inhibition of EROD in DE71 exposure to both gill epithelia and hepatocytes. The results show that cultured gill epithelia more rapidly induce EROD and are slightly more sensitive than cultured hepatocytes, and could be used as a rapid and sensitive tool for screening chemicals and monitoring environmental AhR agonist toxicants. (c) 2006 Elsevier B.V. All rights reserved.

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Testate amoebae are an important and abundant component of aquatic ecosystems. Our knowledge of their distribution and the species inventory in Asia is still limited. This paper describes a new planktonic Difflugia from Lake Mulan, province of Hubei, China. These findings are of taxonomic, as well as biogeographic significance because Difflugia mulanensis nov. spec. is a rare and perhaps the only locally distributed member of the well-known urceolate division within this most species-rich genus of lobose testate amoebae. We have studied its morphology and biometry with light and scanning electron microscopical methods. D. mulanensis differs from related species by its very large wide funnel-shaped apertural collar which normally exceeds the width of the test, a relatively long neck, its rounded apical end and the presence of only one nucleus. All shell parameters are normally distributed with low variability. Only the collar height is more variable. This shows that D. mulanensis is a size-monomorphic species. (c) 2005 Elsevier GrnbH. All rights reserved.

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A culture gill epithelium from seawater-adapted tilapia (Oreochromis niloticus) was developed for testing PAHs and dioxin-like contaminants in seawater. The epithelia consists two to three layers of epithelial cells incorporating both pavement cells and mitochondria-rich cells (MRCs). Polarity and a stable transepithelial resistance (TER) were maintained. and closely resembled those in fish gills in vivo. The tightness (integrity) of the epithelia remained unchanged upon exposure to benzo[a]pyrene (B[a]P). 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3,3',4,4',5-pentachlorobiphenyl (PCB#126), while a concentration-dependent response of EROD activity in the epithelia was induced within 18-24 h when the apical side was exposed to these toxicants. The 24 h EC50 of EROD activity was 2.77 x 10(-7) M for PCB#126, 1.85 x 10(-7) M for B[a]P and 7.38 x 10(-10) M for TCDD. showing: that the preparation was not only sensitive to PAHs and dioxin-like compounds, but also able to produce inductive potency of AhR agonists that generally agreed with those derived from other established in vitro and in vivo systems. The results suggest, that the cultured gill epithelia from seawater-adapted tilapia may serve as a simple. rapid and cost-effective tool for assessing exposure and potential effects of toxicants in marine waters. (C) 2004 Elsevier B.V. All rights reserved.

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The original description of Myxobolus longisporus Nie et Li, 1992, the species infecting gills of Cyprinus carpio haematopterus L., is supplemented with new data on the spore morphology and pathogenicity. Spores are elongate pyriform with pointed anterior end, 15.7 (15.5-16.5) mum long, 6.7 (6-8) mum wide and 5.5 mum thick. Sutural ridge is straight and narrow. Mucus envelope is lacking. Two equal-sized elongate pyriform polar capsules are 8.5 mum long and 2.5 mum wide with convergent long axes. Polar filament coiled perpendicularly to the long axis of the capsule makes 9 (8-10) turns. Posterior end of polar capsules exceeds mid-spore by 15-20%. Cyst-like plasmodia are localised in the gill secondary lamellae. The infection is described in adult big host specimens. Gross lesions manifested as dark red colouration of gill tissues were restricted to the ventral part of the first gill arches. Remarkable site specificity (apical part of secondary lamellae) was observed in the course of development of microscopic lesions. M. longisporus is characterised also on the molecular level using sequences of SSU rRNA gene. Phylogenetic analysis based on these sequences has allowed clearer phylogenetic relationships to be established with other species of the genus Myxobolus sequenced to date.

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Two new rotifera species, Brachionus huangi n. sp, and Lecane chinesensis n. sp. are described and illustrated from different localities in China. The main distinguishing taxonomic features of B. huangi are three pairs of apical spines, a pair of symmetrical caudal spines and a wide caudal projection. For L. chinesensis, the main characteristics are the two-sided small extentions of the foot pseudosegment, the long and innercurved apical spines and ventral lorica anteriorly narrower than the dorsal one.

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常绿阔叶林以其富饶的生物资源、丰富的生物多样性和巨大的生态与环境效益引起了人们越来越大的重视,它的研究已成为国际植被科学界关注的主题之一。我国分布着世界上面积最大的亚热带常绿阔叶林,在世界植被中具有重要地位,它的分布表现出明显的地带性差异,存在着多样的植物群系及其对应的气候特征。但是在植物功能性状领域,与全球范围其它生物群系相比,常绿阔叶林物种的研究较少,其功能性状间、功能性状与环境间的关系尚不清晰。 本研究以常绿阔叶林木本植物的当年生小枝为对象,试图从小枝水平上的生物量分配格局、叶片大小与数量的权衡关系、小枝茎的构型效应、叶片元素化学计量学,以及小枝大小的成本与效益分析等方面,较为系统地揭示小枝水平上的植物功能性状间及其与气候间的关系。因此,在华西雨屏带内部的不同纬度设置峨眉-青城-雷波-平武的温度梯度进行比较,并对有降水差异的川西南偏湿性(雷波)与偏干性常绿阔叶林(西昌)进行对比研究,同时在不同山体进行不同海拔梯度的比较研究。 本文主要研究结果如下: (1)小枝生物量分配格局叶水平上,叶片重-叶柄重(Y轴vs.X轴,下同)呈斜率小于1的异速生长关系,表明叶柄对叶内部的生物量分配影响显著。小枝水平上,叶和茎的生物量以及它们与小枝总生物量间基本呈等速生长关系,表明大的小枝或大叶物种不一定在叶生物量的分配上占优势。不同生活型间,在小枝或者茎的生物量一定时,常绿物种叶片的生物量比例较落叶物种稍高。与温度和水分较优越(峨眉及其低海拔)的生境相比,在相对低湿(螺髻)与低温(平武)的生境中的植物会减少对叶的投入而增加对支撑部分的投资比例。 (2)小枝叶片大小与数量的权衡无论是不同气候带还是不同生活型以及不同海拔梯度,叶片大小与出叶强度基本都是呈负的等速生长关系,表明了叶片大小-数量在小枝水平上的权衡。在不同气候梯度的对比中,叶片数量(出叶强度)一定时,高温和高水分生境(峨眉)比低温(平武)和低湿(螺髻山)生境中的物种的叶片大小(质量和面积)更大,表明不同生境的比较中,小的叶片可能具有较高的出叶强度和更高的适合度收益。“出叶强度优势”(Leafingintensitypremium)假说可能不适宜解释不同生境物种叶片大小差异。 (3)小枝茎的构型效应虽然茎长和茎径与叶片大小都呈正相关关系,与出叶强度都呈负相关关系,但茎长/茎径比与叶/茎生物量之比呈负相关关系;与叶片的大小呈负相关关系,与出叶强度呈正相关关系。这说明小枝构型能影响小枝叶/茎生物量分配和叶大小-数量的权衡关系。其影响机制可能是小枝内部的顶端优势。另外,茎长/茎径比在低湿和低温等不利生境中的植物中较高,而在降水和温度较适宜环境中较低。 (4)叶片C、N、P化学计量学N含量和P含量,C/N比和比叶重(LMA,leafmassperarea)呈正的等速生长关系,而N和LMA,P和LMA呈负的等速生长关系。在LMA一定时,C/N比随着生境胁迫压力的增加而降低,N、P含量随着生境压力的增加而增加。在P含量一定时,N含量随着生境压力的增加而降低,即N/P比在生境条件较优(峨眉及其低海拔)时较高。常绿和落叶植物叶片的N/P比没有差异,在LMA一定时,常绿植物的N、P含量较高、C/N比较低。总之,植物的C、N、P化学计量学特征受叶片属性如LMA与气候,及其相互作用的影响。 (5)小枝大小的代价与效益分析、TLA与小枝总重总叶面积(TLA,totalleafarea,Y轴,下同)与总叶重(X轴)均呈斜率小于1的异速生长关系,TLA与小枝横切面积呈斜率为1的等速生长关系。表明叶片面积的增加总是小于叶重和小枝总重的增加,随着小枝的增大,它的叶面积支撑效率下降。在热量和降水优越的生境(峨眉及其低海拔)中,相同小枝重或者相同茎横切面积的小枝,其叶面积支撑效率较低湿与低温环境下(螺髻山、平武及高海拔)的高。 总体上,本文初步研究了小枝水平上可能存在的以下三种权衡关系:叶-茎生物量分配权衡;叶片大小-数量的权衡;小枝茎长-茎径的权衡关系,以及气候要素等对这三种权衡关系的影响。在此基础上,我们还讨论了这些权衡关系的可能形成机制,及其与物种生态适应的联系。本研究丰富了生活史对策中关于权衡关系的研究内容,为我国常绿阔叶林功能生态学研究积累了材料。 Evergreen broad-leaved forests are attracting much more attention from vegetation ecologists than ever before because of their abundant nature resource and biological diversity, and also great ecological benefits. China has the largest distribution of subtropical evergreen broad-leaved forests (temperate rainforests) that are typical and representative in the world. The forests span over more than ten degrees in latitude and more than 30 degrees in longitude, providing an ideal place to study plant functional ecology, i.e., the climatic effect on plant functional traits and the relationship between the traits. However, relative to the other biomes, there are few studies addressing functional ecology of the plant species from subtropical evergreen broad-leaved forests. In this study, I focused on the leaf size-twig size spectrum of the woody species of subtropical evergreen broad-leaved forests in southwestern china. I collected data on leaf size and number, twig size in terms of both mass and volume, and stem architecture from five temperate mountains, and then I analyzed the relationships between leaf and stem biomass and between leaf size and number, the effect of stem length/diameter ratio on biomass allocation and on the relationship between leaf size and number, leaf C:N:P stoichiometry, and the twig efficiency of supporting leaf area in relation to twig size. I also addressed the climate effect on the spectrum. The temperature gradient from warm to cool sites was represented by Emei Mountain, Qingchengshan, Leibo, and Pingwu, and the rainfall gradient was assumed to emerge from the comparison between Leibo (High) and Luojishan (Low). In addition, altitudinal effects were analyzed with comparisons between low and high altitudes for each mountains. My main results are as follows. Isometric relationships were found between leaf mass and twig mass and between lamina mass and twig mass, suggesting that the biomass allocation to leaves or laminas was independent of twig mass. Petiole mass disproportionably increase with respect to lamina mass and twig mass, indicating the importance of leaf petioles to the within-twig biomass allocation. In addition, the investigated species tended to have a larger leaf and lamina mass, but a smaller stem mass at a given twig mass at favorable environments including warm and humid sites or at low altitude than unfavorable habitats, which might be due to the large requirements in physical support and transporting safety for the species living at unfavorable conditions. Moreover, the evergreen species invested more in leaves and laminas than the deciduous at given stem or twig biomass within any specified habitats. Negative, isometric scaling relationships between leaf number and size broadly existed in the species regardless of climate, altitude, and life forms, suggesting a leaf size/number trade-off within twigs. Along the climatic gradients, at given leaf number or leafing intensity, the leaves were larger in the favorable environments than the poor habitats. This suggested that the fitness benefit gained by small leaves could be larger than that with high leafing intensity in the stressful sites. I concluded that the “leafing intensity premium” hypothesis was not appropriate to interpreting between-habitat variation in leaf size. Both stem length and diameter were positively correlated to leaf size but negatively correlated to leafing intensity. The ratio of stem length to diameter was negatively correlated to leaf mass fraction, and it was negatively correlated to leaf size but positively correlated to leafing intensity. This suggested that the stem architecture influenced twig biomass allocation and the relationship between leaf size and number. The mechanism underlying the architectural effect might lie in the apical dominance within twig. Moreover, the ratio was greater in unfavorable habitats but smaller in favorable environments. Positive, isometric relationships were found between N and P contents per leaf mass, and between C/N ratio and leaf mass per area (LMA), but N and P contents scaled negatively to LMA. C/N ratio decreased but N and P increased with increasing habitat stress at a given LMA. N content declined with increasing habitat stress at given P content. These indicated that N/P and C/N were higher but LMA was lower in favorable habitats than in the other circumstances. The evergreen and deciduous species were non-heterogeneous in N/P, but the evergreen species have higher N and P contents and lower C/N than the deciduous ones. In general, C:N:P stoichiometry were related to both climatic conditions and other important functional traits like LMA. Total leaf area (TLA) allometricly scaled to leaf mass with a slope shallower than 1, similar to the relationship between TLA and total twig mass (leaf mass plus stem mass), suggesting that TLA failed to keep pace with the increase of leaf mass and twig size. However, TLA scaled isometricly to twig cross-sectional area. Thus, it could be inferred that the twig efficiency of displaying leaf area decreased with increasing twig size. In addition, the efficiency at a given twig size was large in favorable than unfavorable habitats. In general, in this preliminary study, I studied three tradeoff relationships within twigs, i.e., between leaf and stem biomass, between leaf number and size, and between stem length and diameter, as well as the climatic effect on the relationships. I discussed the mechanisms underlying the tradeoff relationships in view of biophysics and eco-physiology of plants. I believe that this study can serve as important materials advancing plant functional ecology of subtropical forest and that it will improve the understanding of life history strategies of plants from this particular biome.

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The Nd-III ion in hexa-mu-chloro-1:2 kappa(2)Cl;1:3 kappa(2)Cl;1:4 kappa(2)Cl-hexachloro-2 kappa(2)Cl,3 kappa(2)Cl,4 kappa(2)Cl- [1 (eta(6))- toluene] trialuminiumneodymium has distorted pentagonal bipyramidal coordination geometry. Five Cl atoms form the equatorial plane, and the toluene ring and the sixth Cl atom occupy the apical sites. The average Nd-C(eta(6)) and Nd-Cl distances are 2.926 (5) and 2.857 (1) Angstrom, respectively.