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101.
Fran?oise Martz Minna Turunen Riitta Julkunen-Tiitto Hanne Suokanerva Marja-Liisa Sutinen 《Polar Biology》2011,34(3):411-420
The long-term effects of enhanced UV-B radiation on the content and composition of leaf phenolics in Epilobium
angustifolium L. and Eriophorum
russeolum Fries ex Hartman were studied in northern Finland (68°N) using two UV-B enhancement experiments, both simulating UV-BCIE radiation and corresponding to a 20% loss of ozone layer. High proportions of hydrolyzable tannins (69%) and condensed tannins
(66%) characterized both Epilobium and Eriophorum leaves, respectively. No UV treatment effect was detected in the content or composition of Epilobium leaf soluble phenolics, whereas significant UV effects were detected in Eriophorum leaves in a developmental-specific manner. At the end of the growing season, the proportion of total soluble phenolics was
higher in leaves exposed to enhanced UV-A and UV-B radiation than in the control leaves, but the phenolic composition was
not significantly modified. This study introduces a new example on plants’ phenolic response to UV radiation being species-specific
and detectable only at certain developmental stages. Possible consequences of increased phenolic content in forage plants
for selection and digestibility by reindeer are, however, not yet known. 相似文献
102.
In search for factors which could drive the spectacular spring migrations of pre-reproductive queens of bumblebees and social wasps, we made a literature search of potential mortality factors of individuals and colonies. Although the role of parasitism cannot be ruled out, we highlight the potential of vole cyclicity in explaining the migrations. Because the spatial scale of vole-cycle asynchrony is located at the same level (γ scale) as the range of migratory movements, spring flights could rid bumblebees and wasps of strong nest-site competition among colony-founding queens, and of severe predation by voles in high vole-density regions, to take advantage of abundant, empty vole burrows as nest sites in low-predation, relatively vole-free areas. As a corollary of the migratory movements, relaxed parasite pressure is expected. 相似文献
103.
Anne Kasurinen Petri A. Peltonen Riitta Julkunen-Tiitto Elina Vapaavuori Visa Nuutinen Toini Holopainen Jarmo K. Holopainen 《Plant and Soil》2007,292(1-2):25-43
Two field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O3 for three growing seasons (1999–2001). The phenolic compounds of naturally abscised leaf litter were analyzed in order to
determine the possible CO2- and O3-induced changes in the litter quality. The potential litter-mediated CO2 and O3 effects on litter-feeding soil macrofauna (detritivore) performance were assessed in microcosm experiments, i.e., the relative
growth rates (RGR) of Lumbricus terrestris and Porcellio scaber, the relative consumption rates (RCR) of P. scaber, and mortality of the test animals were measured. The leaf litter grown under elevated CO2 had increased concentrations (weight per mass unit) and contents (weight per leaf) of phenolic acids, flavonol glycosides,
condensed tannins and total measured phenolics. Elevated O3 increased the concentrations of 3,4’-dihydroxypropiophenone 3-β-d-glucoside (DHPPG) and flavonoid aglycones but only under ambient CO2. However, elevated O3 effects on the content of some low-molecular-weight phenolic (LMWP) compounds (i.e. phenolic acids, DHPPG, flavonoid aglycones)
and total LMWP changed over time emphasizing the importance of conducting long-term (>3 years) exposure studies. In general,
RGR of young L. terrestris was affected by the litter quality changes induced by elevated CO2 and O3, as the animal growth rates were reduced when they were fed with CO2- and O3-exposed leaf litter of clone 80 in Experiment 1. P. scaber RCR or RGR responses to CO2- and O3-induced changes in litter quality were more variable and inconsistent, and neither were there any litter-mediated CO2 and O3 effects on animal mortality in these microcosm experiments. In conclusion, elevated CO2 has the potential to alter silver birch leaf litter quality, but the possible O3 effects on phenolic compounds and litter-mediated CO2 and O3 effects on detritivores are more difficult to validate. 相似文献
104.
Aino Rummukainen Riitta Julkunen-Tiitto Mikko Räisänen Tarja Lehto 《Plant and Soil》2007,292(1-2):13-23
The increase in concentrations of phenolic compounds in boron (B) deficiency has been demonstrated in many herbaceous plant
species, but information on woody plants is scarce. It has been suggested that accumulation of phenolic compounds plays a
role in the development of cold hardiness in herbaceous plants but also that B deficiency decreases winter hardiness. Here
we study the effects of B nutrition on phenolic compounds in Norway spruce (Picea abies L.) in the course of cold acclimation. Phenolic compounds were analysed in Norway spruce seedlings from three different B-fertilisation
treatments in two harvests: non-acclimated and cold-acclimated seedlings. Norway spruce phenolic compounds consisted mainly
of condensed tannins. During B deficiency, condensed tannins and monocoumaroyl–astragalin der. 1 increased in non-acclimated
seedlings. The increase in tannins was 21%, which was nearly significant. However, the effect of B on phenolic compounds was
almost absent in cold-acclimated seedlings. The condensed tannin concentration increased much more with time in the simulated
autumn than due to B deficiency, and we conclude that the B effect was probably not large enough to be important for the hardening
of the seedlings. The total phenolic concentrations more than doubled during the course of cold hardening suggesting that
phenolics have a role in the winter hardiness in Norway spruce. 相似文献
105.
Sarita Keski-Saari Maarit Falck Jaakko Heinonen Jerzy Zoń Riitta Julkunen-Tiitto 《Trees - Structure and Function》2007,21(3):263-272
We studied phenolic metabolism and plant growth in birch seedlings at the beginning of their development by inhibiting phenylalanine
ammonia lyase (PAL), which is the first committed step in phenylpropanoid metabolism. Betula pubescens (Ehrh.) seeds were germinated in inhibitor-free media and the seedlings were transferred to hydroponic culture at the cotyledon
stage. They were 6 days old at the start of the experiment, which lasted for 3 weeks. PAL activity was inhibited by three
different concentrations of 2-aminoindane-2-phosphonic acid monohydrate (AIP) in the growing media. At the end of 3 weeks,
phenolics in all plant parts (roots, stem, cotyledons, first, second and third true leaves) were determined. AIP inhibited
strongly the accumulation of phenolic acids, salidroside, rhododendrins, ellagitannins and their precursors, flavan-3-ols,
and soluble condensed tannins. The accumulation of lignin and flavonol glycoside derivatives was moderately inhibited. The
accumulation of flavonol glycosides, such as quercetin glycosides and kaempferol glycosides, was not generally inhibited,
even in leaves that emerged during the experiment, while the accumulation of insoluble condensed tannins was inhibited only
slightly and not in all plant parts. This suggests that flavonol glycosides, which may have a UV-B protective role, and insoluble
condensed tannins, which may have structural functions, are prioritized in seedling development. Inhibition of PAL with AIP
decreased seedling growth and possible reasons for this are discussed.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
106.
Line Nybakken Sarita Keski-Saari Maarit A. Falck Riitta Julkunen-Tiitto 《Trees - Structure and Function》2007,21(3):273-281
Phenylalanine ammonia lyase (PAL) plays a key role in phenylpropanoid metabolism, catalyzing the deamination of phenylalanine
(Phe) to form trans-cinnamic acid. Inhibitors of PAL have been used to study the physiological role of the different compounds derived from trans-cinnamic acid, and to test theories about a trade-off between growth and defence in plants. In a previous study with birch
(Betula pubescens Ehrh.) seedlings, the PAL inhibitor 2-aminoindane-2-phosphonic acid monohydrate (AIP) caused an accumulation of Phe and a
strong decrease in the quantity of simple phenolics, soluble condensed tannins and growth, whereas flavonol glycosides were
generally not affected. The present study demonstrates restoration of secondary metabolism in the previously AIP treated birch
seedlings. Our results indicate that Phe accumulated during PAL inhibition could be partly used to increase the content of
the phenolic acids, flavan-3-ols and to some extent the soluble condensed tannins. Seedling growth also increased when the
supply of PAL inhibitor ceased. We thereby show that the inhibition of PAL by AIP in vivo is reversible, at least for moderate
AIP concentrations and the rate of restoration is dependent on the inhibitor concentration. 相似文献
107.
108.
Anne-Mari Luhtanen Eeva Eronen-Rasimus Hermanni Kaartokallio Janne-Markus Rintala Riitta Autio Elina Roine 《Extremophiles : life under extreme conditions》2014,18(1):121-130
In search for sea ice bacteria and their phages from the Baltic Sea ice, two ice samples were collected from land-fast ice in a south-west Finland coastal site in February and March 2011. Bacteria were isolated from the melted sea ice samples and phages were screened from the same samples for 43 purified isolates. Plaque-producing phages were found for 15 bacterial isolates at 3 °C. Ten phage isolates were successfully plaque purified and eight of them were chosen for particle purification to analyze their morphology and structural proteins. Phage 1/32 infecting an isolate affiliated to phylum Bacteroidetes (Flavobacterium sp.) is a siphovirus and six phages infecting isolates affiliated to γ-Proteobacteria (Shewanella sp.) hosts were myoviruses. Cross titrations between the hosts showed that all studied phages are host specific. Phage solutions, host growth and phage infection were tested in different temperatures revealing phage temperature tolerance up to 45 °C, whereas phage infection was in most of the cases retarded above 15 °C. This study is the first to report isolation and cultivation of ice bacteria and cold-active phages from the Baltic Sea ice. 相似文献
109.
110.