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DAVID FURTH RENATA ALBRECHT KARIN MURASZKO G. EVELYN HUTCHINSON 《Systematic Entomology》1978,3(2):147-152
Scanning electron microscope studies were performed on the palar pegs of male forelegs of Trichocorixa sexcincta, Sigara alternata and Hesperocorixa interrupta. The studies showed the pegs to be basically conical and chevron-ridged, with a wide base that tapered of to a narrow apex. Clear species differences were apparent with respect to the size of the peg, the number of ridges on an individual peg, and the number and arrangement of the pegs on the pala. The possible behavioural and evolutionary significance of the palar pegs is discussed in relation to mating. 相似文献
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KARIN RIEMANN-ZÜRNECK 《Zoologica scripta》1978,7(1-4):145-153
Actinoscyphia saginata (Verrill, 1882; type species) and Actinoscyphia aurelia (Stephenson, 1918) are redescribed with special reference to characters of diagnostic significance in order to differentiate the two species both inhabiting the 2000 m slope region of the North Atlantic. In situ photograph of A. aurelia off the North West African coast shows it to display a novel life form type in expanding its bi-lobed tentacular disc like a Venus-fly-trap and standing on the muddy sediment with a small, non-adhesive base penetrating just below the surface of the sediment. The peculiar nematocyst equipment found in both species makes it necessary to rehabilitate the family Actinoscyphiidae Stephenson, 1920. The systematic position of the family is discussed and eventually the Actinoscyphiidae is considered as sister group (sensu Hennig) of the Hormathiidae. Because of the loss of acontia in the Actinoscyphiidae, this taxon is considered to be the more advanced one. Chondrodactis japonica Wassilieff, 1908, is found to belong to the genus Actinoscyphia. 相似文献
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Cyclic AMP and Calcium in Relaxation in Intestinal Smooth Muscle 总被引:3,自引:0,他引:3
WE have studied the role of cyclic AMP in relaxation of smooth muscle and elucidated the mechanism of its action. 相似文献
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KARIN ANDRIOLO 《American anthropologist》2006,108(1):100-113
The inspiration I take from J. M. Coetzee's book Elizabeth Costello (2003) is his advocacy of imagining as an alternative to rational thought. Imagining, as I understand him, is mindwork that engages the body as an experiential and metaphorical site. I apply this notion of imagining to suicides conducted in the service of political protest: The fatal hunger strike of ten prisoners in Northern Ireland in 1981 and Jan Palach's self-immolation in Prague in 1969. Three questions direct the exploration of their trajectories: What feeds the hope for the effectiveness of protest suicides? How do they use the body as a performance site? Do such suicides call for an ethics of attentiveness? 相似文献
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HENDRIK TSCHOEP YVES GIBON PETRONIA CARILLO PATRICK ARMENGAUD MAREK SZECOWKA ADRIANO NUNES-NESI ALISDAIR R. FERNIE KARIN KOEHL & MARK STITT 《Plant, cell & environment》2009,32(3):300-318
We have established a simple soil-based experimental system that allows a small and sustained restriction of growth of Arabidopsis by low nitrogen (N). Plants were grown in a large volume of a peat–vermiculite mix that contained very low levels of inorganic N. As a control, inorganic N was added in solid form to the peat–vermiculite mix, or plants were grown in conventional nutrient-rich solids. The low N growth regime led to a sustained 20% decrease of the relative growth rate over a period of 2 weeks, resulting in a two- to threefold decrease in biomass in 35- to 40-day-old plants. Plants in the low N regime contained lower levels of nitrate, lower nitrate reductase activity, lower levels of malate, fumarate and other organic acids and slightly higher levels of starch, as expected from published studies of N-limited plants. However, their rosette protein content was unaltered, and total and many individual amino acid levels increased compared with N-replete plants. This metabolic phenotype reveals that Arabidopsis responds adaptively to low N by decreasing the rate of growth, while maintaining the overall protein content, and maintaining or even increasing the levels of many amino acids. 相似文献
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NINA YASUDA SATOSHI NAGAI MASAMI HAMAGUCHI KEN OKAJI† KARIN GÉRARD‡ KAZUO NADAOKA§ 《Molecular ecology》2009,18(8):1574-1590
Population outbreaks of the coral-eating starfish, Acanthaster planci , are hypothesized to spread to many localities in the Indo-Pacific Ocean through dispersal of planktonic larvae. To elucidate the gene flow of A. planci across the Indo-Pacific in relation to ocean currents and to test the larval dispersal hypothesis, the genetic structure among 23 samples over the Indo-Pacific was analysed using seven highly polymorphic microsatellite loci. The F -statistics and genetic admixture analysis detected genetically distinct groups in accordance with ocean current systems, that is, the Southeast African group (Kenya and Mayotte), the Northwestern Pacific group (the Philippines and Japan), Palau, the North Central Pacific group (Majuro and Pohnpei), the Great Barrier Reef, Fiji, and French Polynesia, with a large genetic break between the Indian and Pacific Oceans. A pattern of significant isolation by distance was observed among all samples ( P = 0.001, r = 0.88, n = 253, Mantel test), indicating restricted gene flow among the samples in accordance with geographical distances. The data also indicated strong gene flow within the Southeast African, Northwestern Pacific, and Great Barrier Reef groups. These results suggest that the western boundary currents have strong influence on gene flow of this species and may trigger secondary outbreaks. 相似文献
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KARIN NORÉN ERS ANGERBJÖRN PÁLL HERSTEINSSON 《Biological journal of the Linnean Society. Linnean Society of London》2009,97(1):18-26
The genetic composition of a population reflects several aspects of the organism and its environment. The Icelandic Arctic fox population exceeds 8000 individuals and is comprised of both coastal and inland foxes. Several factors may affect within-population movement and subsequent genetic population structure. A narrow isthmus and sheep-proof fences may prevent movement between the north-western and central part and glacial rivers may reduce movement between the eastern and central part of Iceland. Moreover, population density and habitat characteristics can influence movement behaviour further. Here, we investigate the genetic structure in the Icelandic Arctic fox population ( n = 108) using 10 microsatellite loci. Despite large glacial rivers, we found low divergence between the central and eastern part, suggesting extensive movement between these areas. However, both model- and frequency-based analyses suggest that the north-western part is genetically differentiated from the rest of Iceland (FST = 0.04, DS = 0.094), corresponding to 100–200 generations of complete isolation. This suggests that the fences cannot be the sole cause of divergence. Rather, the isthmus causes limited movement between the regions, implying that protection in the Hornstrandir Nature Reserve has a minimal impact on Arctic fox population size in the rest of Iceland. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 18–26. 相似文献
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MARTIN ZUSCHIN MATHIAS HARZHAUSER KARIN SAUERMOSER 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2006,39(1):65-80
The best hope for understanding global diversity patterns is to compare local assemblages, which are mostly preserved in taphonomically-complex shell beds. The present study investigates the variability in faunal composition and diversity at the scale of a single outcrop. A total of 152 species (3315 shells) occurred in 25 samples from 5 tempestitic shell beds. Although sampling intensity was high, total species richness was not captured by far at the hierarchical levels present (outcrop, shell beds, samples) because the majority of species is rare. In contrast, sampling intensity was sufficient to cover the most abundant species, as indicated by stable evenness values. Four taxa dominate the assemblage, but their rank order differs strongly between individual shell beds and individual samples; significant differences between some shell beds are evident for faunal composition, and one shell bed differs from all others with respect to species accumulation curves. Within shell beds, rarefaction curves are generally characterized by strongly overlapping confidence intervals, but outliers occur in three of five shell beds. Patchiness is additionally indicated by a wide scatter of diversity indices in some shell beds and by a wide scatter of samples of one shell bed in an ordination on faunal composition. Most of the outcrop-scale variability in faunal composition and diversity can be related to differences between shell beds. This suggests that sampling a single shell bed of the outcrop is insufficient to characterize the local fauna and its diversity, even when sampling intensity (i.e. the number of samples and shells) within the shell bed was high. Similarly, a single sample from such a shell bed may not be sufficient to characterize its diversity, even when the number of counted shells was high. It is therefore confirmed that sampling strategy and sampling intensity are crucial to confidently characterize the shelly assemblages at such a small spatial scale and that dispersed sampling effort with many small replicate samples will characterize a local assemblage and its diversity better than a few large samples. Diversity comparisons of individual samples between localities must account for the high variability present at the smaller spatial scale, as observed in our study. 相似文献