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Phylogenetic analyses of 33 genera of Rubiaceae were performed using morphological and a few chemical characters. Parsimony analysis based on 29 characters resulted in eight equally parsimonious trees, with a consistency index of 0.40 and a retention index of 0.69. These results were compared to a phylogenetic analysis of the same genera based on chloroplast DNA restriction site data. There are discrepancies between the two analyses, but if we consider groupings reflected in the present classification there is much congruency. With the exception of four genera, all the genera are positioned in the same group of taxa in the two analyses. Clades of taxa representing three of the four subfamilies (~the Antirheoideae, ~the Rubioideae, and the ~Ixoroideae) are monophyletic, while the fourth subfamily Cinchonoideae is shown to be paraphyletic. Both analyses support a widened tribe Chiococceae, including the former subtribe Portlandiinae (Condamineeae). Furthermore, in both analyses the tribe Hamelieae is placed outside the subfamily Rubioideae where it is now housed. In search for the most plausible sister group to the Rubiaceae, the genus Cinchona (Rubiaceae) was analyzed together with 13 genera of the Loganiaceae, Nerium (Apocynaceae), and Exacum (Gentianaceae). Cornus (Comaceae), Olea (Oleaceae), and these two genera together were used as outgroups. The analysis, including 25 characters, 16 taxa, and with Cornus and Olea together as an outgroup, resulted in four equally parsimonious trees, with a consistency index of 0.53 and a retention index of 0.62. The non-Loganiaceae taxa Cinchona (Rubiaceae), Nerium (Apocynaceae), and Exacum (Gentianaceae) were all found to have their closest relatives within the Loganiaceae indicating that the Loganiaceae are paraphyletic and ought to be reclassified. As a result of the morphological data the most plausible sister group to the Rubiaceae is the tribe Gelsemieae of the Loganiaceae.  相似文献   

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本文描述中国广西马钱科度量草属4新种,即:凤山度量草(MitreolapingtaoiD.FangetD.H.Qin)、长叶度量草(M.macrophyllaD.FangetD.H.Qin)、匙叶度量草(M.spathulifoliaD.FangetL.S.Zhou)和紫脉度量草(M.purpureonerviaD.FangetX.H.Lu)。  相似文献   

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《Ibis》1954,96(2):315-315
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Cell proliferation, differentiation and migration have been studied in the sebaceous glands of DBA-2 mice in the resting (telogen) phase of hair growth. Cells labelled by a single injection of tritiated thymidine start to leave the glands of adult male mice 5 days later. About 80% of the proliferative cells in the basal layer have a cell cycle time of 40 hr or less. In 18% of the proliferative cells G1 is at least 4 days long and 16% have a G2 phase longer than 17 hr. The S phase is about 7.5 hr long and cells spend at least 21 hr in the basal layer before migrating into the differentiating cell region. The glands of mature female and immature mice are smaller than those of the mature male. They have fewer, smaller cells and a much lower labelling index.  相似文献   

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《Ibis》1952,94(4):636-653
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无量山种子植物区系的特有现象   总被引:18,自引:6,他引:12  
地处滇中南的无量山地区迄今计有种子植物207科,1026属,2540种,其中东亚特有科10个,中国特有属27个,无量山特有种子67个,这一地区不仅植物种类丰富,而且特有现象较为显著,在对科级持有现象进行较细致的研究后,本文认国无量山具有较多的分类系统上隔离的东亚特有科反映了该地作为东亚古老植物区系的一部分,其地质历史与整个东亚是一致的,且与东亚植物区系的发端密切相关,属的特有现象表明,地处中国特有  相似文献   

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Drosophila subobscura is a Palearctic species that was first detected in the New World in Puerto Montt (Chile) in February 1978. Since that time, it has spread over a broad area and increased in population density. The South American populations exhibit a high level of chromosomal polymorphism: 20 different arrangements exist, distributed among five chromosomes. Chromosomal arrangement heterozygosity varies from 0.55 to 0.61 in the nine populations examined. Incipient clines in the frequencies of the arrangements are appearing; these clines follow the same latitudinal direction as in the Old World. Wing length significantly decreases with latitude, as it does in Europe. The colonization of South America by D. subobscura appears to be a major natural experiment with outcomes that duplicate the distributional patterns—in chromosomal polymorphism and in wing length—observed in the Old World, thereby strongly supporting the adaptive significance of these patterns. The data show a very rapid effect of natural selection promoting genetic differentiation among natural populations.  相似文献   

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THE LIFE-HISTORY OF THE PLUM-RUST IN ENGLAND.   总被引:1,自引:1,他引:0  
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《Ibis》1952,94(3):543-543
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1. The solvent action of a neutral salt upon a protein, oxyhemoglobin, has been found identical to the solvent action of a neutral salt upon a bi-bivalent or uni-quadrivalent compound. 2. The solubility of oxyhemoglobin in phosphate solutions of varying ionic strength has been defined by the equation: log See PDF for Equation in which µ is the ionic strength, and S 0 is the solubility in the absence of salt. 3. The values of S 0 have been calculated to be 12.2, 11.2, and 13.1 gm. per liter respectively at pH 6.4, 6.6, and 6.8. 4. The relatively great solubility of oxyhemoglobin in water has been ascribed to the strong affinity constants for acid and base of certain groups in oxyhemoglobin. 5. The small change in the solubility of oxyhemoglobin effected by neutral salts suggests that but few such groups are dissociated in oxyhemoglobin in the state in which it crystallizes near its isoelectric point. 6. Certain of the other properties of oxyhemoglobin, such as its low viscosity, are considered in the light of its molecular weight and its valence type.  相似文献   

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ROOT-STRUCTURE IN THE CENTRAL CYLINDER OF THE HYPOCOTYL.   总被引:1,自引:1,他引:0  
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