ORIGIN AND BIOGEOGRAPHY OF AESCULUS L. (HIPPOCASTANACEAE): A MOLECULAR PHYLOGENETIC PERSPECTIVE

Sequences of chloroplast gene matK and internal transcribed spacers of nuclear ribosomal RNA genes were used for phylogenetic analyses of Aesculus, a genus currently distributed in eastern Asia, eastern and western North America, and southeastern Europe. Phylogenetic relationships inferred from these molecular data are highly correlated with the geographic distributions of species. The identified lineages closely correspond to the five sections previously recognized on the basis of morphology. Ancestral character-state reconstruction, a molecular clock, and fossil evidence were used to infer the origin and biogeographic history of the genus within a phylogenetic framework. Based on the molecular phylogenetic reconstruction of the genus, sequence divergence, and paleontological evidence, we infer that the genus originated during the transition from the Cretaceous to the Tertiary (~65 M.Y.B.P.) at a high latitude in eastern Asia and spread into North America and Europe as an element of the “boreotropical flora”; the current disjunct distribution of the genus resulted from geological and climatic changes during the Tertiary.     

永久型70kD热休克蛋白在白菜花发育过程中的免疫组织化学定位

利用免疫组织化学技术研究了永久型热休克蛋白ＨＳＣ７０在白菜花各组织中的分布。结果表明：在正常温度条件下,ＨＳＣ７０在小孢子母细胞、四分体细胞、花药壁绒毡层细胞中分布最多,在花原基、花托的维管组织、花粉母细胞以及发育早期的胚珠中的表达也较多。该结果与其他人用核酸杂交、同位素示踪等技术所得结果基本一致,本文对ＨＳＣ７０在白菜花不同组织中的分布与其功能的关系进行了初步讨论。     

湖北省发现中国瘰螈

2009年6～9月,在咸丰县丁寨乡、甲马池乡采集到一批两栖类标本,经鉴定其中中国瘰螈(Paramesotriton chinesis)为湖北省新纪录种。     

Approaching risk assessment of complex disease development in horse chestnut trees: a chemical ecologist's perspective

Abstract The chemo‐ecological predispositions were investigated for the development of a complex disease on the basis of an insect–fungus mutualism using the system of horse chestnuts (Aesculus hippocastanum and Aesculus x carnea), the horse chestnut leaf miner (Cameraria ohridella) and the biotrophic powdery mildew (Erysiphe flexuosa). Both C. ohridella and E. flexuosa can appear on the same horse chestnut leaf tissue simultaneously. The olfactory detection of fungal infection by the insect, its ability to discriminate the potentially mutualistic fungus from other fungi and the impact of fungal infection on insect oviposition were examined. Gas chromatography coupled with mass spectroscopic and electroantennographic detection by C. ohridella (GC‐MS/EAD) was used to assess the olfactory detection of fungal‐infected A. hippocastanum and A. x carnea leaves by C. ohridella. Infection‐related compounds, such as benzyl alcohol, dodecane, tridecane and methyl salicylate as well as fungus‐related C8 compounds, are perceived by C. ohridella. The discrimination of E. flexuosa from another phytopathogenic fungus, such as Guignardia aesculi, is based primarily on the differing pattern of C8 compounds of these fungi. Oviposition on fungal‐infected leaves of A. hippocastanum and leaves treated with fungal‐related compounds showed that C. ohridella is able to respond to the modifications in the leaf volatile profiles of horse chestnuts caused by the different fungal infections. Thus, from the perception point of view, the necessary predispositions for the development of a close insect–fungus relation between the biotrophic fungus E. flexuosa and the leaf‐mining insect C. ohridella are fulfilled. However, decreased oviposition on infected leaves does not enhance the selective contact between the species. As a consequence, an important predisposition for forming an insect–fungus mutualism is not fulfilled by these two species and, according to this approach, the risk of forming a complex disease can be assessed as low.     

圆萼刺参的化学成分研究

自圆萼刺参[Morina chinesis(Botal.ex Diels]的乙醇提取物中分离到8个化合物。经波谱分析及TLC对照鉴定为新化合物4-O-α-D-呋喃阿洛酮糖-α-D-吡喃葡萄糖(1)和已知化合物芦丁(2),积雪草酸(3),胡萝卜甙(4),芥子醇(5),6α,23-二羟基熊果酸(6),熊果酸(7)及葡萄糖(8)。     

A seasonal cycle of cell wall structure is accompanied by a cyclical rearrangement of cortical microtubules in fusiform cambial cells within taproots of Aesculus hippocastanum (Hippocastanaceae)

Aspects of the structure and ultrastructure of the fusiform cambial cells of the taproot of Aesculus hippocastanum L. (horse chestnut) are described in relation to the seasonal cycle of cambial activity and dormancy. Particular attention is directed at cell walls and the microtubule and microfilament components of the cytoskeleton, using a range of cytochemical and immunolocalization techniques at the optical and electron-microscopical levels. During the dormant phase, cambial cell walls are thick and multi-layered, the cells possess a helical array of cortical microtubules, and microfilament bundles are oriented axially. In the early stages of reactivation, vesicle-like profiles are associated with the cell walls, whereas arrangement of the cytoskeletal elements remains unchanged. In the succeeding active phase, the cell walls are thin, and cortical microtubules form a random array, although microfilament bundles maintain a near-axial orientation. The observations are discussed in relation to the seasonal cycle of wall structure and cortical microtubule rearrangement within the vascular cambium of hardwood trees. It is suggested that the cell-wall thickening at the onset of cambial dormancy, which is associated with the presence of a helical cortical microtubule array, should be considered to be secondary wall thickening, and that selective lysis of this secondary wall layer during cambial reactivation restores the thinner, primary wall found around active cambial cells.     

Estimating ancestral distributions of lineages with uncertain sister groups： a statistical approach to Dispersal-Vicariance Analysis and a case using Aesculus L. （Sapindaceae） including fossils

We propose a simple statistical approach for using Dispersal-Vicariance Analysis （DIVA） software to infer biogeographic histories without fully bifurcating trees. In this approach, ancestral ranges are first optimized for a sample of Bayesian trees. The probability P of an ancestral range r at a node is then calculated as P（rY） = ∑t^n=1 F（rY）t Pt where Y is a node, and F（rY） is the frequency of range r among all the optimal solutions resulting from DIVA optimization at node Y, t is one of n topologies optimized, and Pt is the probability of topology t. Node Y is a hypothesized ancestor shared by a specific crown lineage and the sister of that lineage ＂x＂, where x may vary due to phylogenetic uncertainty （polytomies and nodes with posterior probability 〈 100%）. Using this method, the ancestral distribution at Y can be estimated to provide inference of the geographic origins of the specific crown group of interest. This approach takes into account phylogenetic uncertainty as well as uncertainty from DIVA optimization. It is an extension of the previously described method called Bayes-DIVA, which pairs Bayesian phylogenetic analysis with biogeographic analysis using DIVA. Further, we show that the probability P of an ancestral range at Y calculated using this method does not equate to pp＊F（rY） on the Bayesian consensus tree when both variables are 〈 100%, where pp is the posterior probability and F（rY） is the frequency of range r for the node containing the specific crown group. We tested our DIVA-Bayes approach using Aesculus L., which has major lineages unresolved as a polytomy. We inferred the most probable geographic origins of the five traditional sections of Aesculus and ofAesculus californica Nutt. and examined range subdivisions at parental nodes of these lineages. Additionally, we used the DIVA-Bayes data from Aesculus to quantify the effects on biogeographic inference of including two wildcard fossil taxa in phylogenetic analysis. Our analysis resolved the geographic