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31.
Fecundity of the autumnal moth depends on pooled geometrid abundance without a time lag: implications for cyclic population dynamics 总被引:1,自引:0,他引:1
1. The abundance and fecundity-related body size variation of the cyclic autumnal moth Epirrita autumnata were monitored from the early increase phase and throughout the outbreak to the end of the density decline in northernmost Norway during 1999-2006. Another geometrid, the winter moth Operophtera brumata, did not increase in density until the autumnal moth had its post-peak in 2004, and was at its own peak concurrent with the steeply declining autumnal moth abundance in 2005-06. 2. The body size variables measured (forewing lengths of males and females and hind femur lengths of males) of the autumnal moth showed a similar density-dependent response, i.e. increasing density was associated with decreasing body size and fecundity. Nevertheless, regression analyses clearly ranked the pooled geometrid abundance without a time lag as the best predictor for the body size variation, ahead of the abundance of the autumnal moth or past abundance of all geometrids. 3. Nondelayed effects of lowered food quality and absolute shortage of foliage under congested conditions are the most plausible reasons for reduced body size. 4. Two most commonly proposed causal factors of the autumnal moth population cycle, i.e. delayed inducible resistance of the host plant (mountain birch Betula pubescens czerepanovii) and delayed density-dependent parasitism by specialized hymenopteran parasitoids, cannot easily explain the diverging population trends between the autumnal and winter moths. 5. We suggest that either the inducible resistance of the host tree or the host utilization of the most important parasitoids and/or pathogens have to be strictly species-specific between these closely related moth species to produce the population dynamics observed. That fecundity of the autumnal moth was best related to the pooled geometrid abundance weakens support for the former hypothesis, while our lack of host-specific information limits conclusions about the role of natural enemies. 相似文献
32.
In this study, a new concept for particle size prediction during the fluid bed granulation is presented. Using the process
measurements data obtained from a design of experimental study, predictive partial least squares models were developed for
spraying and drying phases. Measured and calculated process parameters from an instrumented fluid bed granulation environment
were used as explaining factors, whereas an in-line particle size data determined by spatial filtering technique were used
as response. Modeling was carried out by testing all possible combinations of two to six process parameters (factors) of the
total of 41 parameters. Eleven batches were used for model development and four batches for model testing. The selected models
predicted particle size (d
50) well, especially during the spraying phase (Q
2 = 0.86). While the measured in-line d
50 data were markedly influenced by different process failures, e.g., impaired fluidization activity, the predicted data remained
more consistent. This introduced concept can be applied in fluid bed granulation processes if the granulation environment
is soundly instrumented and if reliable real-time particle size data from the design of experiment batches are retrieved for
the model development. 相似文献
33.
Koskela S Söderholm PP Ainasoja M Wennberg T Klika KD Ovcharenko VV Kylänlahti I Auerma T Yli-Kauhaluoma J Pihlaja K Vuorela PM Teeri TH 《Planta》2011,233(1):37-48
A previously isolated cDNA molecule from Gerbera hybrida (Asteraceae) codes for a new chalcone synthase-like polyketide synthase, 2-pyrone synthase (2PS). 2PS is able to synthesise 4-hydroxy-6-methyl-2-pyrone (triacetolactone), a putative precursor for gerberin and parasorboside, two abundant glucosides in gerbera. In this study, we show that gerbera plants transformed with the gene for 2PS in an antisense orientation and unable to synthesise gerberin and parasorboside are susceptible to Botrytis cinerea infection. In addition to the preformed glucosides, the transgenic plants also lack several compounds that are induced in control plants when infected with the mould. Some of these induced substances are effective in inhibiting fungal growth both in vitro and in vivo. Two of the phytoalexins were identified as the aglycones of gerberin and trans-parasorboside. The third phytoalexin is a rare coumarin, 4-hydroxy-5-methylcoumarin; however, it is typical of many plants of the sunflower family Asteraceae. The coumarin cannot be structurally derived from either gerberin or parasorboside, but may be derived from a related polyketide intermediate. 相似文献
34.
Ursula Strandberg Tero Sipilä Mervi Kunnasranta 《Journal of experimental marine biology and ecology》2011,407(2):256-265
We investigated the vertical stratification pattern of fatty acids in the blubber of the freshwater Saimaa ringed seal (Phoca hispida saimensis; n = 35). Blubber was dissected vertically into 3 mm thick sequential subsamples, and the fatty acid composition was analyzed separately for each subsample. The combined vertical fatty acid profiles (expressed as numerical gradients) showed that the blubber of > 1 year old individuals is stratified into three distinguishable layers: superficial (~ 1.5 cm), middle and deep (~ 1 cm). Thickness of the middle layer varied according to the total blubber thickness. We suggest that the observed layering is related to the differences in the tissue temperatures and metabolic activity in the blubber column. The dissimilarity in the fatty acid composition (measured as Euclidean distance) between the different blubber layers and the 5 most important fish prey species available in Lake Saimaa was largest in the superficial blubber. In fact, the fatty acid composition of superficial blubber resembled more that of marine ringed seal (Phoca hispida hispida) blubber than any of the analyzed fish species. The composition closest to that of the prey was found in the deep blubber of the Saimaa ringed seal. The large vertical differences in the fatty acid composition of blubber lipids, which likely affect the vertical distribution of other endogenous or exogenous lipophilic substances as well, will set conditions for the sampling of blubber for biomonitoring and dietary studies. Thus the knowledge on the potential layers with different composition and the depths they span in different individuals (e.g. young versus old; with thin versus thick blubber) is crucial for improving the validity and reliability of monitoring methods utilizing the blubber tissue. 相似文献
35.
Aurore Aubail Jonas Teilmann Rune Dietz Frank Rig��t Tero Harkonen Olle Karlsson Aqqalu Rosing-Asvid Florence Caurant 《Polar Biology》2011,34(9):1411-1420
Recent studies have shown that the complementary analysis of mercury (Hg) concentrations and stable isotopic ratios of nitrogen
(δ15N) and carbon (δ13C) can be useful for investigating the trophic influence on the Hg exposure and accumulation in marine top predators. In this
study, we propose to evaluate the interspecies variability of Hg concentrations in phocids from polar areas and to compare
Hg bioaccumulation between both hemispheres. Mercury concentrations, δ15N and δ13C were measured in fur from 85 individuals representing 7 phocidae species, a Ross seal (Ommatophoca rossii), Weddell seals (Leptonychotes weddellii), crabeater seals (Lobodon carcinophagus), harbour seals (Phoca vitulina), grey seals (Halichoerus grypus), ringed seals (Pusa hispida) and a bearded seal (Erignathus barbatus), from Greenland, Denmark and Antarctica. Our results showed a positive correlation between Hg concentrations and δ15N values among all individuals. Seals from the Northern ecosystems displayed greater Hg concentrations, δ15N and δ13C values than those from the Southern waters. Those geographical differences in Hg and stable isotopes values were likely
due to higher environmental Hg concentrations and somewhat greater number of steps in Arctic food webs. Moreover, dissimilarities
in feeding habits among species were shown through δ15N and δ13C analysis, resulting in an important interspecific variation in fur Hg concentrations. A trophic segregation was observed
between crabeater seals and the other species, resulting from the very specific diet of krill of this species and leading
to the lowest observed Hg concentrations. 相似文献
36.
Pekka Kujala Tero Ahola Neda Ehsani Petri Auvinen Helena Vihinen Leevi Kriinen 《Journal of virology》1999,73(9):7805-7811
Antiserum prepared against an amino-terminal fragment of rubella virus (RUB) nonstructural polyprotein was used to study RUB-infected Vero cells. Replicase protein P150 was associated with vesicles and vacuoles of endolysosomal origin and later with large, convoluted, tubular membrane structures. Newly incorporated bromouridine was associated with the same structures and specifically with small membrane invaginations, spherules, indicating that these structures may be the sites of viral RNA synthesis. 相似文献
37.
Redox‐dependent disulfide bond formation in SAP30L corepressor protein: Implications for structure and function 下载免费PDF全文
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Comparative studies on the food of the black cormorant Phalacrocorax carbo and the harbour seal Phoca vitulina were carried out in two contrasting habitat types. Both species feed predominantly on bottom-dwelling fish. Black cormorants are able to utilize fish found both on vegetation-covered and naked sea beds at a water depth of less than 10 m, while harbour seals feed mainly on soft sea bottoms above 30 m where vegetation is scarce or lacking. The food overlap of the two piscivores is large in environments where large shallow sea bottoms are available, and small in areas where sea bottoms of soft material is found at greater depth. In areas where the shallow bottoms are covered by vegetation only, cormorants are able to feed on the fish species inhabiting this kind of environment. There is no evidence that these predators make a choice regarding prey species. 相似文献