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61.
1. Plant–plant communication has been found to affect interactions between herbivores and plants in several model systems. In these systems, herbivore‐induced volatile chemical cues are emitted and perceived by other plants (receivers), which subsequently change their defensive phenotypes. Most studies have focused on how the effects of volatile cues affect plant damage, whereas herbivore performance has rarely been examined. 2. In this study, it is shown that plant–plant communication between willows reduced the growth rate, feeding rate, and conversion efficiency of some individuals but not others of a generalist caterpillar, Orgyia vetusta. 3. Using a paired, no‐choice trial design, there was substantial variation between caterpillar individuals in their response to willows that had been induced with a volatile plant–plant cue. This variation was explained by feeding parameters of the individual herbivores. Individuals behaved similarly when fed induced and non‐induced willow leaves. Specifically, growth rates of caterpillars that grew rapidly on non‐induced willow leaves were negatively affected by plant–plant cues, but growth rates of caterpillars that grew slowly on non‐induced willow leaves were not affected by the responses to volatiles from neighbouring willows. 4. Induction by volatile plant–plant cues reduced the growth rates of those individual herbivores that caused the greatest damage to willow, but had little effect on weak growers. 相似文献
62.
STEPHANIE JENOUVRIER JEAN-CLAUDE THIBAULT† ANNE VIALLEFONT‡ PATRICK VIDAL§ DIETRICH RISTOW¶ JEAN-LOUIS MOUGIN PIERANDREA BRICHETTI JOHN J. BORG†† VINCENT BRETAGNOLLE 《Global Change Biology》2009,15(1):268-279
To predict the impact of climate change over the whole species distribution range, comparison of adult survival variations over large spatial scale is of primary concern for long-lived species populations that are particularly susceptible to decline if adult survival is reduced. In this study, we estimated and compared adult survival rates between 1989 and 1997 of six populations of Cory's shearwater ( Calonectris diomedea ) spread across 4600 km using capture–recapture models. We showed that mean annual adult survival rates are different among populations along a longitudinal gradient and between sexes. Variation in adult survival is synchronized among populations, with three distinct groups: (1) both females and males of Corsica, Tremiti, and Selvagem (annual survival range 0.88–0.96); (2) both females and males of Frioul and females from Crete (0.82–0.92); and (3) both females and males of Malta and males from Crete (0.74–0.88). The total variation accounted for by the common pattern of variation is on average 71%, suggesting strong environmental forcing. At least 61% of the variation in survival is explained by the Southern Oscillation Index fluctuations. We suggested that Atlantic hurricanes and storms during La Niña years may increase adult mortality for Cory's shearwater during winter months. For long-lived seabird species, variation in adult survival is buffered against environmental variability, although extreme climate conditions such as storms significantly affect adult survival. The effect of climate at large spatial scales on adult survival during the nonbreeding period may lead to synchronization of variation in adult survival over the species' range and has large effects on the meta-population trends. One can thus worry about the future of such long-lived seabirds species under the predictions of higher frequency of extreme large-scale climatic events. 相似文献
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64.
PATRICK J. GAFFNEY 《Nature: New biology》1971,234(52):281-282
THE human plasma protein, fibrinogen, is a disulphide bonded1 dimer2, each unit containing an Aα, Bβ and 8 chain*, interconnected by disulphide bridges3. Thrombin (E.C.3.4.4.-13) releases fibrinopeptides A and B from the Aα and Bβ chains respectively4 to form fibrin monomer (α2β2γ2) ? which polymerizes to form fibrin polymer or clotted fibrin. This polymer, following factor XIII (plasma transglutaminase, fibrin stabilizing factor) mediated crosslinking among the α chains and among the γ chains5, is one of the major and initiating constituents of a thrombus. Fibrinolytic activators, for example, streptokinase (SK) and urokinase (UK), are of thrombolytic value as they convert the thrombus plasminogen to plasmin (E.C.3.4.4.14) which by fibrinolytic action dissolves the thrombus. Whereas the interaction of fibrinogen and plasmin has been well studied6–9, little is known concerning the mechanism of plasmin mediated fibrin clot lysis. I report here on the mechanism of non-cross-linked fibrin clot solubilization in near physiological conditions. 相似文献
65.
PATRICK J. KEELING AMANDA L. DOHERTY-KIRBY EVELYN M. TEH W. FORD DOOLITTLE 《The Journal of eukaryotic microbiology》1996,43(6):468-474
ABSTRACT In searching the genomes of early-diverging protists to study whether the possession of calmodulin is ancestral to all eukaryotes, the gene for calmodulin was identified in Trichomonas vaginalis. This flagellate is a member of the Parabasalia, one of the earliest lineages of recognized eukaryotes to have diverged. This sequence was used to isolate a homologous 1.250-kb fragment from the T. vaginalis genome by inverse polymerase chain reaction. This fragment was also completely sequenced and shown to contain the 3' end of the single-copy calmodulin gene and the 3' end of a gene encoding a protein with high similarity to E2 ubiquitin-conjugating enzymes, a family which has previously only been identified in animals, plants, and fungi. Phylogenetic analysis of 50 members of the E2 family distinguishes at least nine separate subfamilies one of which includes the T. vaginalis E2-homologue and an uncharacterized gene from yeast chromosome XII. 相似文献
66.
RICHARD KARBAN PATRICK GROF‐TISZA MARSHALL MCMUNN HEATHER KHAROUBA MIKAELA HUNTZINGER 《Ecological Entomology》2015,40(6):725-731
1. Climate and, therefore, abiotic conditions, are changing rapidly, and many ecological interactions depend on them. In this study, how abiotic conditions mediate a predator–prey interaction were examined. 2. Caterpillars of Platyprepia virginalis (Boisduval) (Arctiidae) were found previously to be more abundant in wet habitats and thick litter cover compared with drier habitats and little or no litter. We hypothesised that wet litter provided caterpillars with refuges from an important ant predator, Formica lasioides. It was further hypothesised that caterpillars would be able to move at lower temperatures than ants, thus providing them with a thermal refuge. 3. In the lab, caterpillars were more likely to escape ant predation and survive on wet litter and at lower temperatures. At all temperatures, ant recruitment was lower in wet litter than dry litter although ants were more active on litter than bare soil. Thus, wet litter may serve as a habitat refuge for caterpillars from ants. 4. Caterpillars were able to maintain activity at temperatures 8–14 °C lower than F. lasioides. Thus colder temperatures may serve as a thermal refuge for caterpillars from ants. 5. It was hypothesised that caterpillars can escape ant predation when precipitation causes wet litter and at temperatures that they experience commonly in the field. This mismatch between caterpillars and their predators in ability to tolerate wet litter and low temperatures may affect their field distribution and abundance. Expected future warmer and drier conditions may not provide these refuges. 相似文献
67.
FRANÇOIS ORANGE JEAN‐ROBERT DISNAR FRANCES WESTALL DANIEL PRIEUR PATRICK BAILLIF 《Palaeontology》2011,54(5):953-964
Abstract: A series of experiments was conducted to determine the capacity of an archaeal strain, Methanocaldococcus jannaschii, to bind metals and to study the effects of metal binding on the subsequent silicification of the microorganisms. The results showed that M. jannaschii can rapidly bind several metal cations (Fe3+, Ca2+, Pb2+, Zn2+, Cu2+). Considering the lack of silicification of this strain without metal binding, these experiments demonstrate that Fe(III) ion binding to the cell wall components was of fundamental importance for successful silicification and, especially, for the excellent preservation of the cell wall. This study brings new elements to the understanding of fossilization processes, showing that the positive effect of Fe(III) on silicification, already known for Bacteria, can also apply to Archaea and that this preliminary binding can be decisive for the subsequent fossilization of these organisms. Knowledge of these mechanisms can be helpful for the search and the identification of microfossils in both terrestrial and extraterrestrials rocks, and in particular on Mars. 相似文献
68.
69.
At an early stage of secondary development, the metaphloem sieveelements appeared to be the only functional axial transportconduit in fully elongated stems of P. vulgaris plants. Thereis no apparent barrier to the radial transfer of solutes inthe stem apoplast. However, radial transfer through the stemsymplast could be limited by discontinuities resulting fromprotoplast degeneration of the protophloem fibres and developingsecondary xylem fibres. Estimates of possible sucrose fluxesthrough the apoplastic and symplastic routes indicated thatradial photosynthate transfer from the sieve element-companioncell (se-cc) complexes of the stem metaphloem could follow eithercellular route. In the case of apoplastic transfer, the plasmamembrane surface area of the se-cc complexes is only sufficientto support some form of facilitated movement of sucrose. Incontrast, the plasma membrane surface area of the phloem parenchymais sufficient to permit passive diffusion of sucrose to theapoplast. Plasmodesmatal frequencies suggest that any symplastictransfer to the phloem parenchyma from the sieve elements wouldbe via the companion cells. Phaseolus vulgaris, french bean, stem, photosynthate, radial transfer (photosynthates), cellular pathway 相似文献
70.
NEUROPEPTIDE Y RECEPTORS FROM CALF BRAIN: EFFECT OF CRUDE CONUS VENOM PREPARATIONS ON [H]NPY BINDING
EVA CZERWIEC JEAN-PAUL De BACKER GEORGES VAUQUELIN PATRICK M.L. VANDERHEYDEN 《Neurochemistry international》1996,29(6):669-676
NPY receptors are identified in calf frontal cortex and hippocampus membrane preparations by binding of N-[propionyl-3H] neuropeptide Y. Saturation and competition binding data with PYY, NPY-(18–36) and NPY itself fit with a single class of sites: for the radioligand KD = 1.4 ± 0.5 nM, Bmax = 434 ± 180 fmol/mg protein in frontal cortex, KD = 0.7 ± 0.2 nM, Bmax = 267 ± 50 fmol/mg protein in hippocampus. Competition curves of the Y1-subtype selective agonist [Leu31, Pro34]NPY are biphasic in both membrane preparations: high affinity sites (i.e. Y1-subtype) amount to 80% in frontal cortex and 23% in hippocampus. The remaining sites are of the Y2-subtype. Out of 23 Conus venom preparations, 17 inhibit the binding of [3H]NPY in both membrane preparations, but only two of them (from Conus aulicus and C. pennaceus) do so with high potency (ic50 < 5 μg protein/ml). Only one venom preparation (from C. mercator) had weak discriminatory properties (ic50Y2/ic50Y1 = 6). Venom from C. anemone increased the [3H]NPY binding 5-fold and with an ic50 of 15–18 μg protein/ml. This binding occurred to the venom itself and was unrelated to the NPY receptors since it was equally potent when displaced by [Leu31, Pro34]NPY, NPY-(18–36), PYY and NPY. Copyright © 1996 Elsevier Science Ltd 相似文献