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11.
Nitrogen (N) deposition is expected to increase in northwestern Europe the next 50–100 years. The effects of higher N availability on lichens will presumably depend on their capacity to acquire carbon (C), that is, of the timing and duration of the wet and active state. If lichens respond like plants, their C and N status may affect their concentration of carbon-based secondary compounds (CBSCs), and thus their defence against herbivores, detrimental radiation, pathogens and parasites. In the present study we have manipulated N availability and timing and duration of the metabolically active state by spraying lichen transplants in an old spruce forest with rainwater or rainwater with added N corresponding to 50 kg N ha−1 yr−1 . The spraying was applied either at night, in the morning or at noon to also investigate the effect of timing and duration of the active state. Concentrations of N, chlorophyll a (Chl a ) and CBSCs were measured before and after one summer's spraying of 10 thalli in each of four different lichen species; Alectoria sarmentosa, Lobaria scrobiculata, Platismatia glauca , and Xanthoria aureola . The added N was readily taken up by all the lichen species. A. sarmentosa, P. glauca , and X. aureola increased their Chl a concentration in response to increased N, while L. scrobiculata increased Chl a in response to increased active time. None of the studied species reduced their concentration of secondary compounds during the experimental period, but in P. glauca the concentration of all compounds were significantly lower in N-treated thalli compared with those that got only rainwater. The results are consistent with a high degree of constitutive defence in three of four species, and we conclude that all the investigated lichens seem to have rather robust chemical defence systems despite considerable manipulation of the environmental conditions. 相似文献
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NINA ROTHE ANDREW J. GOODAY TOMAS CEDHAGEN JOSÉ FAHRNI J. ALAN HUGHES ANTON PAGE RICHARD B. PEARCE JAN PAWLOWSKI 《Zoological Journal of the Linnean Society》2009,157(3):451-469
We describe three new species of the genus Gromia from bathyal and abyssal depths in the Weddell Sea. The new species are characterized by a combination of morphological and molecular criteria. All three species possess a distinct oral capsule and a layer of ‘honeycomb membranes’, which form the inner part of the organic test wall. Both these features are typical of gromiids. Their identification as gromiids is confirmed by analyses of partial small subunit ribosomal DNA (SSU rDNA) gene sequences. Gromia marmorea sp. nov. is a rounded species with a prominent oral capsule and a characteristically mottled appearance. In Gromia melinus sp. nov. , the test surface exhibits a polygonal pattern of ridges, with a layer of clay particles coating the surface between the ridges. Gromia winnetoui sp. nov. represents an elongate morphotype in which the organic test is enclosed within an agglutinated case, a feature previously unknown in gromiids. Phylogenetic analysis using the maximum‐likelihood method revealed that all three species form distinct clades, reflecting the morphological differences among Weddell Sea species, as well as between deep‐water Southern Ocean Gromia and previously described gromiids. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 157 , 451–469. 相似文献
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LAURA KVIST DAVID GIRALT FRANCISCO VALERA HERBERT HOI ANTON KRISTIN GIORGI DARCHIASHVILI PETER LOVASZI 《Ibis》2011,153(1):98-109
The Lesser Grey Shrike has suffered successive declines in population size and a marked contraction of its breeding range since the early 20th century, largely because of long‐term agricultural intensification. This has resulted in a severely fragmented distribution in Western Europe, with isolated breeding nuclei in Spain, France and Italy and a more continuous distribution in Eastern Europe and Asia. Using a combination of nuclear and mitochondrial markers, we assessed the genetic structure and diversity of Lesser Grey Shrike populations from Western Europe, Central Europe and Asia. There was significant genetic differentiation among three major regional groups, one European and two Asian. Genetic diversity measures were lowest in the smallest and most marginal Spanish population. Limited genetic diversity, combined with rapid population decline, suggests the Spanish population may face extinction in the near future. 相似文献
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CANCHAO YANG ANTON ANTONOV YAN CAI BÅRD G. STOKKE ARNE MOKSNES EIVIN RØSKAFT WEI LIANG 《Ibis》2012,154(1):200-204
We documented brood parasitism by the poorly studied Large Hawk‐Cuckoo on a previously unknown host species, the Chinese Babax. Furthermore, we describe a new egg colour for the Large Hawk‐Cuckoo. The parasitism rate of Chinese Babax nests over 4 years was 6.9% (11 of 159 nests), with significant temporal variation. The Large Hawk‐Cuckoo laid immaculate white eggs that appeared non‐mimetic to the blue Babax eggs, an impression that was confirmed by avian visual modelling. Nevertheless, most Cuckoo eggs were accepted by the host, suggesting that this host–parasite system may be evolutionarily recent. 相似文献
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Translation of Two Messenger RNAs from Lens in a Cell Free System from Krebs II Ascites Cells 总被引:8,自引:0,他引:8
MICHAEL B. MATHEWS MARY OSBORN ANTON J. M. BERNS HANS BLOEMENDAL 《Nature: New biology》1972,236(61):5-7
SPECIALIZED tissues which synthesize only a small number of different proteins offer obvious advantages as sources of specific and pure messenger RNAs (mRNAs). Presumptive mRNAs have been isolated and partially characterized from reticulocytes1,2, muscle3, myelomas4 and eye lens5. The messenger role of 9S RNA from reticulocytes has been established by its ability to direct the synthesis of haemoglobin in cell-free systems from reticulocytes2 and Krebs 11 ascites tumour cells6 and in Xenopus oocytes7. We show here that 10S and 14S RNA fractions from calf lens direct the synthesis of different polypeptide components of lens crystallin in the ascites cell-free system. These results complement and extend the demonstration, in the accompanying article8, that 14S lens RNA is translated in the reticulocyte lysate. 相似文献
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JOSE LUIS BARANELLI REA A. COCUCCI ANA M. ANTON 《Botanical journal of the Linnean Society. Linnean Society of London》1995,119(1):65-76
Studies on Acacia caven (Mol.) Mol. in central Argentina indicate that the species is polygamous (andromonoecious), some plants having a high proportion of staminate heads. Though pollen/ovule ratios of flowers, inflorescences and plants are at a level common for 'facultative xenogamic' systems, controlled pollination shows a marked xenogamy. The ratio between pollen grains in the polyad and the maximum number of seeds per pod is close to one. Observations support the idea of the inflorescence as a specialized reproductive unit with gynoecia functioning as fixed modules in which all or none of its ovules develop into seeds. Mass flowering prior to the growing season, the absence of other floral resources in the community, the high degree of fruiting limitations and scarce insect visitation suggest that, as in other Acacia , the reproductive system of Acacia caven involves a great sacrifice of floral resources. 相似文献
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