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41.
Relationships between parasitoid host range and host defence: a comparative study of egg encapsulation in two related parasitoid species 总被引:1,自引:0,他引:1
Abstract. Parasitoid host range may proceed from traits affecting host suitability, traits affecting parasitoid foraging behaviour, or both. We tested the hypothesis that encapsulation can be used as a reliable indicator of parasitoid host range in two closely related larval endoparasitoids of Lepidoptera. Cotesia glomerata (L.) (Hymenoptera: Braconidae) is gregarious and a generalist on several species of Pieridae, whereas C. rubecula (Marshall) is solitary and specific to Pieris rapae (L.). We determined the effects of host species ( Pieris brassicae (L.), P. napi (L.) and P. rapae ) (Lepidoptera: Pieridae) and host developmental stage (early first, second and third instar) on encapsulation of parasitoid eggs. Host species and parasitoid species, as well as the resulting interaction between these two factors had significant effects on encapsulation of Cotesia eggs. Encapsulation in Pieris hosts was much lower for C. glomerata (<34%, except for second and third instar of P. rapae ) than for C. rubecula (>32%), even when the latter was parasitizing P. rapae. Encapsulation increased with the age of the larvae, although the only significant difference was for C. glomerata. Overall, P. rapae showed a stronger encapsulation reaction than P. brassicae and P. napi. Encapsulation levels of C. glomerata corresponded well to patterns of female host species and host age preference for oviposition and parasitoid larval performance. In contrast, percentages of encapsulation of C. rubecula were not consistent with host preference and host suitability. We argue that encapsulation alone is unlikely to provide a sufficient explanation for C. glomerata and C. rubecula host range. 相似文献
42.
The influence of elevated CO2 on species phenology, growth and reproduction in a Mediterranean old-field community 总被引:1,自引:0,他引:1
MARIE-LAURE NAVAS LAURETTE SONIE JEAN RICHARTE & JACQUES ROY 《Global Change Biology》1997,3(6):523-530
We studied the effects on the phenology, growth and reproduction of 19 Mediterranean species, of elevating the atmospheric CO2 concentration ([CO2 ]) to twice-ambient. Intact monoliths were taken from an old-field and put, during a six month growing season, into growth chambers in which external climatic conditions were mimicked and [CO2 ] was regulated. Fruit set time was significantly changed in six species under elevated [CO2 ] and leaf and branch senescence accelerated in most species. Grasses had fewer leaves and legumes were more branched at peak production under elevated [CO2 ] than under ambient. Plant seed number was not significantly changed under elevated [CO2 ], whereas the reproductive effort of grasses was significantly depressed. Reproductive and vegetative characteristics showed related responses to [CO2 ], as species with enhanced biomass had a hastened fruit set time, a higher number of fruits per plant and a higher reproductive biomass under elevated [CO2 ] than under ambient conditions, while species with depressed biomass had a delayed fruit set time, a lower number of fruits per plant and a lower reproductive biomass. Our results also show a high interspecific variability in [CO2 ] response, but some trends emerged at the family level: the production of vegetative and reproductive modules were depressed in grasses and slightly stimulated in legumes. 相似文献
43.
44.
- Daily and seasonal variations occur in the water content ofHelix aspersa Müller.
- The water content is not constantthroughout 24 hours but fluctuatesby 2 to 10%. There is noapparent daily rhythm.
- Humidity has an effect on the watercontent. Falls in relativehumidity to 60% or less, triggera decrease of the snails' hydration,over a range of temperatures,as well as a brief pause in activity.
- Only external climaticconditions produce noticeable fluctuationsof water content,and they more particularly affect juvenileswhich undergo greaterevaporo-transpiration.
- A seasonal rhythm in water contentexists in Helix aspersa,with maxima during spring and autumnand minima in June andJanuary.
- The water content of juvenilesis always superior to that ofthe adults.
- The water contentaffects the duration of the snail's activephase.
45.
JACQUES F. G. M. MEIS JAN PETER VERHAVE PAUL H. K. JAP ROBERT E. SINDEN JOSEPH H. E. T. MEUWISSEN 《The Journal of eukaryotic microbiology》1983,30(2):361-366
The invasion of liver parenchymal cells by sporozoites of Plasmodium berghei Vincke & Lips, 1948, was studied in vivo using transmission electron microscopy. Livers of Brown Norway rats were examined 30 and 60 min after intraportal injection of 15 million sporozoites each. Sporozoites found after incorporation into vacuoles in hepatocytes were often located near a bile canaliculus at the lateral cell surface, surrounded by hepatocyte lysosomal structures; however, degradation of sporozoites caused by lysosomal digestion inside hepatocytes was never observed. Due to the crescent shape of sporozoites, serial sections were necessary to demonstrate the actual process of invasion of the hepatocyte. The hepatocyte's plasmalemma appeared to invaginate due to the sporozoite's action, thereby creating a parasitophorous vacuole. It was suggested that the sporozoite actively penetrated the hepatocyte; however, no visible depletion of rhoptries and micronemes was observed. 相似文献
46.
RENE ORMIèRES JACQUES BAUDOIN GUY BRUGEROLLE RAYMOND PRALAVORIO 《The Journal of eukaryotic microbiology》1976,23(2):320-328
La présence de diplocaryons à tous les stades de la sporulation d'Octosporea muscaedomesticae Flu, 1911 est mise en évidence ainsi qu'une membrane pansporoblastique autour des sporoblastes en développement et des spores. Le problème présenté par ces 2 faits est discuté. Une évolution étrange des ribosomes périnucléaires et démontrée. Une telle étude ultrastructurale est nécessaire et intéressante car O. muscaedomesticae est l'espèce-type du genre Octosporea. 相似文献
47.
Lamaze, T., Sentenac, H. and Grignon, C. 1987. Orthophosphaterelations of root: NO3effects on orthophosphate influx,accumulation and secretion into the xylem.J. exp. Bot.38: 923934. Orthophosphate (Pi) accumulation by barley (Hordeum vulgareL.) roots was specifically inhibited by NO3 as comparedto Cl and SO42 , and Pi secretion into the xylemwas stimulated. The inhibition of Pi accumulation by NO3was also observed in roots of intact photosynthesizing horsebean(Vicia faba L.), rice (Oryza sativa L.) and soybean (Glycinemax L.) plants. NO3 effects on Pi transport by rootswere more thoroughly investigated with corn (Zea mays L.). Theywere due to intracellular NO3. Pi secretion was stillstimulated by NO3 after Pi withdrawal from the absorptionsolution. 32Pi influx decreased during Pi accumulation, supportingthe hypothesis that this ion allosterically regulated its owntransport system by feedback control. This control was modulatedby other anions: the decrease was more pronounced in the presenceof nitrate. Chronologically, the depressive effect of NO3on 32Pi influx appeared after the inhibition of Pi accumulation.Furthermore, under conditions where Pi accumulation was notaffected by NO3, 32Pi influx and Pi secretion into thexylem became insensitive to the presence of nitrate. Our hypothesisis that the stimulative effect of NO3 on Pi secretionand the depressive one on 32Pi influx are the repercussionsof an increase in the Pi cytosolic concentration due to an NO3-induced decrease in Pi uptake by the vacuoles. Key words: Root, orthophosphate fluxes, orthophosphate accumulation, nitrate, ionic interaction 相似文献
48.
Axis growth commenced only 20 h from imbibition in Phaseolusvulgaris when both uptake of water and oxygen were levellingoff. Cotyledonary dry material was exhausted by day 9, the greatestrates of transfer occurring from day 2. Utilization of reserveprotein proceeded relatively faster than dry matter and proportionatelymore was translocated to the shoot, particularly the leaf blades.Lamina protein and chlorophyll content showed a biphasic increasewith rapid synthesis prior to day 7 being followed by slowerrates up to maximum leaf area on day 17. The level of free aminoacids in the cotyledons fell continuously from day 3 and roseto peak levels in the axis between days 5 and 7. Soluble sugarsincreased throughout the period examined in the axis and accumulatedin the cotyledons prior to day 7. Exogenous application of GA3 had marked morphological effectsupon the seedling though did not significantly alter the distributionof dry matter or protein reserves: 6-BA, in addition to distinctmorphological effects, delayed the mobilization of reservesto the axis. Total amylolytic activity in the cotyledon, optimal at pH 5.5,increased continually from day 3 to 9 whereupon activity abruptlydeclined. This increase was due to the appearance of -amylase;ß-amylase, while present, remained at a constant andcomparatively low level. Peak proteolytic activity occurredprior to that for amylases between days 5 and 7. 6-BA significantlyincreased both amylolytic and proteolytic activities in vitrothough did not alter the changes in levels of free amino acidsor sugars in the reserve tissue and axis. The discrepancy betweenin vivo and in vitro effects of 6-BA may be attributed to concomitanteffects upon seedling development whereby sink capacity is reduced. 相似文献
49.
MICHEL HAMON SYLVIE BOURGOIN YVETTE MOROT-GAUDRY JACQUES GLOWINSKI 《Nature: New biology》1972,237(75):184-187
THE synthesis of serotonin (5-HT) in central serotoninergic neurones seems to depend on the intraneuronal concentrations of the amine. After acute or chronic treatment with a monoamine oxidase inhibitor (MAOI), which induced more than a three-fold increase in 5-HT concentrations, we observed a reduced formation of 3H-5-HT from 3H-tryptophan in the rat brain1. More precisely, this effect could be seen by measuring the accumulation of 3H-5-HT in tissues 15 min after the intracisternal injection of 3H-tryptophan at various times after pheniprazine or pargyline treatments. The 3H-amine accumulation was much less after 3 h than 0.5 h after the MAOI injections. The existence of a 5-HT synthesis regulation by end product inhibition occurring at the first limiting step was proposed to explain these results1. 相似文献
50.
SCHOCH PAUL G.; JACQUES ROGER; LECHARNY ALAIN; SIBI MONIQUE 《Journal of experimental botany》1984,35(10):1405-1409
Using appropriate coloured lights, we show that phytochromeis involved in stomatal differentiation. This photoperceptionis located within the whole shoot. This action is also shownfor in vitro leaves. The nature of the morphogenetic informationis discussed. Key words: Stomatal differentiation, Phytochromy, Vigna sinensis L. 相似文献