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1.
Represented Communities: Fiji and World Decolonization. John D. Kelly and Martha Kaplan. Chicago: University of Chicago Press, 2001. 243 pp.
Cultural Memory: Reconfiguring History and Identity in the Postcolonial Pacific. Jeannerte Marie Mageo. Honolulu: University of Hawai'i Press, 2001. 222 pp.
In Colonial New Guinea: Anthropological Perspectives. Naomi M. McPherson. ed. Pittsburgh: University of Pittsburgh Press, 2001. 264 pp.  相似文献   

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The metabolism of the herbicide L-phosphinothricin (L-Pt) was analyzed in tobacco (Nicotiana tabacum), alfalfa (Medicago sativa), and carrot (Daucus carota). In transgenic, Pt-resistant plants expressing the Pt-N-acetyltransferase gene (pat), L-Pt was acetylated, resulting in two forms of N-acetyl-Pt (ac-Pt). In transgenic plants expressing only low pat-encoded acetylating activity as well as in genetically unmodified plants, three metabolic compounds 4-methylphosphinico-2-oxo-butanoic acid, 3-methylphosphinico-propanoic acid (MPP), and 4-methylphosphinico-2-hydroxy-butanoic acid (MHB) were identified. Hence, the transgene-encoded acetylation of L-Pt competes with a plant-specific degradation. The compounds MPP, MHB, and ac-Pt were found to be the final, stable products of the plant's metabolic pathways. The mobility of these stable compounds in the plant was investigated: L-Pt as well as the derived metabolites were found to be preferentially transported to the upper regions of the plant.  相似文献   

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It was shown that despite fundamental differences in the organization of the tegument of cystacanths and the cyst wall of cysticeroids, they have a number of features similar in localization, morphology, terms of formation, and functional value. These include a powerful outer layer of glycocalyx on the surface of the tegument, filling of the distal department with dense substance, and the presence of complicated fibrillar systems. It is supposed that the nature of these particularities is convergent and is determined by the similarity of the life cycles of Hymenolepidata and Acanthocephala.  相似文献   

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The increase in size of the proloculus in successive populations ofPalorbitolina lenticularis is used to distinguish different evolutionary stages within the phyletic line of that species. These, in turn, enable a subdivision of the Upper Barremian-Lower Aptian time-span in the absence of stratigraphically more characteristic forms.  相似文献   

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Summary The peanut worm Sipunculus nudus and the lugworm Arenicola marina are inhabitants of intertidal flats. Both species may be exposed to H2S within their habitat. Sulphide concentrations in the vicinity of A. marina burrows are as high as 340 mol · 1-1, whereas the pore water in sipuncle areas contains much lower sulphide levels of 13 mol · 1-1 at most. During in vivo sulphide incubations, H2S increases within the coelomic fluid of both species. In S. nudus the concentration of total sulphide after 8 h is about 40% of that of the incubation medium containing 200 and 1000 mol · 1-1, respectively, which is partly due to the acidification of the coelomic fluid by 0.2 pH units during anaerobiosis. After 8 h, the sulphide concentration in A. marina was only 15% of that in the incubation medium containing 1000 mol · 1-1. When oxygen is available, both species oxidize sulphide to thiosulphate, but in A. marina this capability is more pronounced than in S. nudus. If sulphide is not completely oxidized internally both intertidal worms switch to an anaerobic metabolism as indicated by the accumulation of opines and succinate.Abbreviations ATP adenosine triphosphate - HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid - HPLC high-performance liquid chromatography - wwt wet weight  相似文献   

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During spiralian development, the first pair of nephridia forms anterior to the mouth. Each organ consists of a few cells, which is characteristic for spiralian larvae. In nemerteans, one of the unambiguously spiralian taxa, so far protonephridia, has been reported only in advanced pilidium larvae, where they likely persist as juvenile and adult nephridia. These organs have not been recorded in larvae of the basally branching nemertean taxa. In search for these organs, we examined the ultrastructure of pelagic planuliform larvae of the palaeonemerteans Carinoma mutabilis and Cephalothrix (Procephalothrix) filiformis. In both species, a pair of protonephridia is located at the level of the stomodaeum. Each protonephridium of C. mutabilis consists of two terminal cells, two duct cells and one nephropore cell, while that of C. filiformis consists of three terminal cells, three duct cells and one nephropore cell. In C. mutabilis and in C. filiformis, all terminal cells contribute to forming a compound filtration structure. In both species, the protonephridia seem to develop subepidermally, since in C. filiformis, the nephropore cells pierce the larval epidermis and in C. mutabilis, the nephropores are initially covered by the binucleated multiciliated trophoblast cells. On the fifth day, these cells degenerate, so that the protonephridium becomes functional. The occurrence of protonephridia in the larvae of both paleonemertean species is in accordance with the hypothesis that a common ancestor of Nemertea and Trochozoa had a larval stage with a pair of protonephridia. This does not contradict previous hypotheses on placing the Nemertea as an ingroup of the Trochozoa or Spiralia (= Lophotrochozoa). Whether these protonephridia are restricted to the larval phase or whether they are transformed into the adult protonephridia, like those of the pilidium larva, remains to be answered.  相似文献   

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The homeobox gene Distal-less (Dll) is well known for its participation in the development of arthropod limbs and their derivatives. Dll activity has been described for all groups of arthropods, but also for molluscs, echinoderms and vertebrates. Generally, Dll participates in the establishment of the proximo-distal-axis and differentiation along this axis. During our investigation of the expression pattern in the silverfish Lepisma saccharina and the horseshoe crab Limulus polyphemus, we found several expressions in late stages which cannot be explained with the "normal" limb-specific function. The antenna, cerci and terminal filament of the silverfish show a striped expression; single cells on the labrum, mandibles, maxillary palps and anal valves are also strongly stained by the Dll antibody. In addition to cell groups in the developing ganglia of the CNS, in the coxal endites and several nerve cells in femur and the trochanter of the prosomal limbs, the whole prosomal shield of Limulus polyphemus is surrounded by Dll-positive cell clusters. Furthermore, the lateral processes of the opisthosoma and the edges of the opisthosomal appendages are Dll positive. To get an indication of the cell fate of these regions, we examined hatched larvae and juvenile stages of both species with the SEM. We found a striking correlation of these Dll-positive areas and different sense organs, especially mechanoreceptors. Since many sense organs in arthropods are situated on the limbs, interpretation of the Dll expression in limbs is problematical. This has critical implications for comparative analysis of Dll expression patterns between arthropods and for the claim of homology between limb-like structures. Furthermore, we discuss the possibility of convergent appendage evolution in various bilaterian groups based on the improvement of spatial sensory resolution.  相似文献   

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Natural hybridization among wingless carabid beetles of the subgenusOhomopterus (Carabidae, genusCarabus) is reviewed, and its significance in the evolution of this subgenus discussed. Natural hybridization occurs between parapatric species of similar size. Two case studies of natural hybridization suggest that natural hybridization could have affected the evolution of this subgenus in different ways. When there is a large difference in genital morphology between hybridizing species, interspecific copulation often results in genital injuries that causes mortality of copulating individuals, and hence reduces the fitness of hybridizing individuals greatly. In such a case, hybridization may be effective in maintaining the parapatric distribution of the two species, and in the long term, may promote reinforcement selection for traits which are effective in prezygotic reproductive isolation. When the morphological difference in genitalia is not so large as to cause genital injury, a hybrid population may be established at the intermediate zone between two parental species, provided that the immigration rates of the two species into the intermediate zone are small. Thus, natural hybridization may have contributed to both divergence and reticulate evolution in this subgenus.  相似文献   

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Erwin Meyer 《Ecography》1985,8(2):141-150
The research area includes subalpine meadows, alder communities, dwarf-shrub heaths, lichen heaths and highalpine meadows (1960 m–3090 m a.s.l.). The material consists of 4419 Julidae (31.6% adult) collected by extraction of litter samples (66.4%), in pitfall traps (26.3%) and by handsampling (7.3%). Cylindroiulus meinerti (Verhoeff) only occurred below 2000 m; Leptoiulus saltuvagus (Verhoeff) was mainly found at Alnus viridis sites; Leptoiulus simplex (Verhoeff) had its main distribution in the lichen heath (2200-2300 m); Ommatoiulus sabulosus (L.) was found most frequently in the subalpine meadow and Leptoiulus alemannicus (Verhoeff) occurred up to 2800 m without any altitudinal concentration. Adults of L. saltuvagus showed only one distinct activity peak in September, those of L. simplex were diplochronous (June/September) and O. sabulosus summer stenochronous (July). L. saltuvagus reached maturity in stage IX (only males), X or XI after four or five Years. In their first year of growth the members of a generation reached the third or fourth stage, in the second year the sixth or seventh, in the third year the eighth or ninth. Females could carry full-sized eggs in the autumn of the fourth year in the tenth stage or in the fifth year in stage eleven. Apparently eggs may be laid in spring of the fifth or sixth year. Overwintering density of L saltuvagus in alder litter was found to be 215.6 ± 38.7 inds m?2, the mean biomass 1.16 g m?2(max. 1.88 g m?2). Mean annual production during the growth period of 4-5 months was in the order of 0.85 g m?2 (max. 1.36 g m?2).  相似文献   

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Leucadendron is a moderately large genus of Proteaceae almost entirely restricted to the Cape Floristic Region of southern Africa. The genus is unusual in being dioecious and sexually dimorphic. ITS sequence data were obtained from 62 of the 96 currently recognized taxa (85 species and 11 subspecies). Phylogenetic analyses were conducted under Maximum Likelihood and parsimony and resolved nine groups of species with varying degrees of bootstrap support, but relationships between these groups are largely unsupported. The phylogeny conflicts with the current taxonomic arrangement, which is based mainly on fruit morphology. The two sections of the genus, Alatosperma and Leucadendron, and several subsections within these sections, are resolved as non-monophyletic. This means that taxonomically important characters (such as fruit shape) have evolved multiple times, as the species with nut-like fruit (resolved into two of the nine groups) appear to have evolved independently from ancestors with winged fruit. Based on the topology obtained, the life history traits of anemophily, myrmechochory, and re-sprouting have also originated multiple times. Dispersal-Vicariance (DIVA) analysis suggests that the genus had an ancestral area in the Karoo Mountain and Southeastern phytogeographic centres of endemism in the southwestern Cape.  相似文献   

15.
Zhu M  He W  Gao E  Lin L  Zhang Y  Dai L  Wang R  Wang B  Wang M 《Life sciences》2012,90(13-14):519-524
AimsA bridging ligand 2,4,6-pyridine tricarboxylic acid (H3ptc) and its manganese(II) complex [Mn(Hptc)(phen)(OH)]n(Hptc = 2,4,6-pyridine tricarboxylic acid, phen = 1,10-phenanthroline) have been synthesized and characterized.Main methodsThe interaction with DNA (HeLa and KB) was carried out by fluorescence spectrum and gel electrophoresis assay. In vitro apoptosis assay and cytotoxicity assay detect the manganese (II) complex interaction with cancer cells.Key findingsFluorescence spectrum demonstrated the ability of the complexes to interact with DNA in an intercalative mode. Gel electrophoresis assay exhibited more effective DNA-cleavage activity. In vitro apoptosis assay of the complexes were examined on HeLa and KB cells, exhibited cytotoxic specificity and a significant cancer cell inhibitory rate.SignificanceThe complex may be a latent antitumor agent as a result of its unique interaction mode with DNA and cancer cells inhibition effect.  相似文献   

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Hybridization and polyploidy are widely believed to be important sources of evolutionary novelty in plant evolution. Both can lead to novel gene combinations and/or novel patterns of gene expression, which in turn provide the variation on which natural selection can act. Here, we use nuclear and plastid gene trees, in conjunction with morphological data and genome size measurements, to show that both processes have been important in shaping the evolution of the angiosperm genus Mercurialis, particularly a clade of annual lineages that shows exceptional variation in the sexual system. Our results indicate that hexaploid populations of M. annua, in which the rare sexual system androdioecy is common (the occurrence of males and hermaphrodites) is of allopolyploid origin involving hybridization between an autotetraploid lineage of M. annua and the related diploid species M. huetii. We discuss the possibility that androdioecy may have evolved as a result of hybridization between dioecious M. huetii and monoecious tetraploid M. annua, an event that brought together the genes for specialist males with those for hermaphrodites.  相似文献   

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Plant and Soil - Rumex alpinus is a native plant in the mountains of Europe whose distribution has partly been affected by its utilization as a vegetable and medicinal herb. The distribution of...  相似文献   

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The objective of this study was to determine the basic population‐specific parameters necessary for fish stock assessment in the Gulf of Annaba and to compare these with data from other Mediterranean regions. Black sea bream Spondyliosoma cantharus (Linnaeus, 1758) (N = 501) were collected monthly from January to December 2008 along the Algerian eastern coasts. More than 22 fish were collected each month and ranged in size from 13.4 to 40 cm total length, weighing from 36 to 1080 g eviscerated weight. Biological sampling included weighing and measuring the fish, gonad weighing, sex and maturity stage determination, and age estimation through otolith readings. Validity of the otolith readings for estimating age and growth was supported using the back‐calculation method. Estimated parameters of the von Bertalanffy model are: L = 33.54 cm, W = 633.46 g, = 0.52 year?1 and to = ?0.04 year. The growth performance index (φ) is: 2.76. The length‐weight relationship is: EW = 4.4.10?6 TL3.23. The spawning period occurred from February to May, while the gamete emission peaked in April. Females reached sexual maturity at 19.3 cm (2 years) and males at 21.3 cm (3 years). Sexual inversion occurs at approximately 24.3 cm. Spondyliosoma cantharus was characterized as being a protogynic hermaphrodite.  相似文献   

19.
Knowing how the diversity of sharks, rays and chimaeras (Chondrichthyes) is distributed helps us to design strategies to conserve these highly-vulnerable predators and their habitats. Here, we analyzed the spatial distribution of chondrichthyan species richness in the Southwest Atlantic (34–56oS), and its relationship with environmental variables and marine fronts, by using a dataset obtained before the major development of industrial trawling fisheries. We also explored the relationship between richness and reported catches of chondrichthyans from commercial, demersal fisheries. Generalized linear models were used to assess the relationship of species richness with environmental variables; with marine fronts and with commercial catches. Species richness increased towards the north, particularly close inshore and on the outer shelf, with cells of highest richness found north of 48oS. Dissolved oxygen was related negatively with richness; depth, latitude and longitude were also related with richness, but to a lesser extent. Chondrichthyan diversity hotspots, i.e. cells with richness higher than the 90% percentile of the richness distribution, were more likely to occur on marine fronts than elsewhere. High chondrichhtyan catches were significantly associated to hotspots, but low-catch areas were not related to coldspots, i.e. cells with less than the 10% percentile of the richness distribution. Areas of high richness of chondrichthyans coincide with high levels of catches and are used by other species of high conservation concern. Given the importance of these areas to multiple species in the Southwest Atlantic, any conservation strategy based on a network of protected areas should include marine fronts.  相似文献   

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