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The basal clade Burnetiamorpha is known from only two specimens representing two genera, Proburnetia from the Severodvinskian horizon of the Vyatka River Basin in the Kotelnich district of Russia, and Burnetia from the Dicynodon Assemblage Zone of the Beaufort Group of South Africa. Both genera are of Late Tatarian (Late Permian) age. This paper describes the cranial morphology of a new genus of burnetiamorph, Bullacephalus , from the Late Permian Tapinocephalus Assemblage Zone of the Beaufort Group of South Africa. It is known from a relatively complete skull and lower jaw and is the best preserved burnetiamorph yet discovered. Apart from being the oldest member of the clade, Bullacephalus is also morphologically the least derived and provides new evidence on the phylogeny of this poorly understood group of basal therapsids.  相似文献   
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Abstract. Adult death's head hawkmoths (Acherontia species) have a unique feeding biology as cleptoparasites of honeybees, stealing honey from the combs, rather than imbibing nectar from flowers. The moths have a range of features, both morphological and behavioural, that enable them to successfully enter, feed and escape from the colonies. These adaptations may vary among the three Acherontia species and allow them each to target different species of honeybee. A cladistic analysis is presented of the hawkmoths of tribe Acherontiini. The study aims to resolve the relationships of the genera and species of Acherontiini, with a particular focus on the three species of Acherontia. The dataset comprises sixty‐five characters derived from adult, larval and pupal morphology, and larva host‐plant biology. These data are analysed using equal weighting and implied weighting. Acherontiini and each constituent genus are recovered as monophyletic. However, within Coelonia, there is ambiguity in that the sister‐species relationships C. brevis+C. fulvinotata and C. fulvinotata + C. solani are equally parsimonious under both weighting schemes. Furthermore, under equal weighting Agrius is placed equally parsimoniously as the sister group of either Acherontia + Coelonia or Callosphingia. Under implied weighting, however, only the latter relationship is most parsimonious (fit). Within Acherontia, A. atropos and A. styx are always recovered as sister species to the exclusion of A. lachesis. The results of the phylogenetic analysis provide an objective basis for future studies of the unique cleptoparasitic association of these moths.  相似文献   
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Purification and characterization of Dolichos lablab lectin   总被引:1,自引:0,他引:1  
Mo  H; Meah  Y; Moore  JG; Goldstein  IJ 《Glycobiology》1999,9(2):173-179
The mannose/glucose-binding Dolichos lablab lectin (designated DLL) has been purified from seeds of Dolichos lablab (hyacinth bean) to electrophoretic homogeneity by affinity chromatography on an ovalbumin- Sepharose 4B column. The purified lectin gave a single symmetric protein peak with an apparent molecular mass of 67 kDa on gel filtration chromatography, and five bands ranging from 10 kDa to 22 kDa upon SDS-PAGE. N-Terminal sequence analysis of these bands revealed subunit heterogeneity due to posttranslational proteolytic truncation at different sites mostly at the carboxyl terminus. The carbohydrate binding properties of the purified lectin were investigated by three different approaches: hemagglutination inhibition assay, quantitative precipitation inhibition assay, and ELISA. On the basis of these studies, it is concluded that the Dolichos lablab lectin has neither an extended carbohydrate combining site, nor a hydrophobic binding site adjacent to it. The carbohydrate combining site of DLL appears to most effectively accommodate a nonreducing terminal alpha-d-mannosyl unit, and to be complementary to the C-3, C-4, and C-6 equatorial hydroxyl groups of alpha-d-mannopyranosyl and alpha-d-glucopyranosyl residues. DLL strongly precipitates murine IgM but not IgG, and the recent finding that this lectin interacts specifically with NIH 3T3 fibroblasts transfected with the Flt3 tyrosine kinase receptor and preserves human cord blood stem cells and progenitors in a quiescent state for prolonged periods in culture, make this lectin a valuable tool in biomedical research.   相似文献   
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Summary A core sampler developed for use in sampling water-filled tree-holes is described. This apparatus consists of an auger mechanism that fits inside the conventional corer tube. Its construction is simple and inexpensive and the resulting instrument is both portable and easy to use. Resumen Una descripción de un tubo saca-testigos dise?ado para tomar muestras en cavidades de árboles conteniendo agua es presentada. El aparato consiste de un mecanismo taladrante que se ajusta dentro del tubo del saca-testigos convencional. Su construcción es simple y barata, y el instrumento es portátil y fácil de usar.  相似文献   
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Summary    Ecological restoration activities, including reforestation, often involve the use of herbicides for the removal of weedy plant cover. Little is known, however, about the effects of herbicides on assemblages of non-target organisms that colonize restored patches. We describe a field experiment to investigate effects of glyphosate herbicide (Roundup® Biactive™) on rainforest-associated soil- and litter-dwelling macro-arthropods. Our experimental protocol differed in two ways from other ecotoxicological studies of herbicides. First, we applied herbicide at a rate considerably greater than the manufacturer's recommended maximum in order to simulate worst-case scenarios that may occur in the practice of forest restoration. Second, our field experiment was carried out under dense canopy cover with sparse understorey vegetation, so that indirect impacts caused by the loss of existing vegetation were eliminated. Paired herbicide-treated and control plots were created within five rainforest remnants on the Maleny plateau of subtropical eastern Australia. Macro-arthropods were collected using litter extraction before, approximately 3 days after, and 3 months after herbicide application. Responses of arthropods were analysed at two levels of taxonomic resolution: 'coarse' arthropods (arthropods sorted to Order/Class), and ant species. Our results suggest that the use of glyphosate herbicide formulated as Roundup® Biactive™ is suitable for the control of unwanted plants in rainforest restoration sites as it appears to have minimal impact on assemblages of soil and litter macro-arthropods or at least those typical of intact rainforest.  相似文献   
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