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21.
Jorma Tahvanainen Riitta Julkunen-Tiitto Matti Rousi Paul B. Reichardt 《Chemoecology》1991,2(1):49-54
Summary A sample of one-year-old seedlings of European white birch (Betula pendula) was analyzed to determine the content of sugars, phenolics and terpenoid compounds. Two vertical segments of each seedling were analyzed separately. The number of resin droplets, which correlates strongly and negatively with feeding by the mountain hare, was also counted on the bark of experimental seedlings. The variation in the palatability of birch seedlings to mountain hare was determined primarily by the most abundant terpenoid, papyriferic acid. On the other hand, the resistance to hare feeding at the seedling bases, which are frequently attacked by voles, appeared to be dependent on other components, apparently phenolic substances. Sugars did not affect the resistance of the tested seedlings. The variation among experimental seedlings was much greater for secondary substances, especially terpenoid compounds, than for sugars. It is suggested that this high variation in protective compounds may be an adaptive trait selected for by the feeding of generalist herbivores. 相似文献
22.
Summary. The nutritive value of tree foliage for herbivores
decreases rapidly with leaf maturation, due in particular to the decline
in leaf nitrogen content. Since the amino acid content of plants differs
from the need of herbivores for individual amino acids, we examined
developmental changes in the contents of amino acids throughout the
growth season of mountain birch. The contents of free and protein-bound
amino acids, as well as essential and nonessential ones, displayed
different patterns with leaf maturation, suggesting that total nitrogen
or protein levels are poor predictors of the nutritive status of leaves.
The contents of protein-bound amino acids were 100 times higher than
those of free amino acids, indicating that the role of free amino acids
in nutrition of herbivores is probably less important than that of
protein-bound amino acids. Among protein-bound amino acids, both the
absolute and the relative contents of two nitrogen-rich essential amino
acids, lysine and arginine, decreased during early leaf growth,
presumably reducing nitrogen availability in developing leaves.
Essential amino acids were mainly positively related to each other,
suggesting the co-ordinated regulation of their synthesis. Changes in
correlations among individual free amino acids reflected developmental
changes in allocation preferences between biosynthesis pathways with
leaf growth.
Received 31 January 2003; accepted 17 March 2003.
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Correspondence to: Teija Ruuhola, e-mail: teiruu@utu.fi 相似文献
23.
Human industrial activities have caused environmental uranium (U) pollution, resulting in uranium(VI) had radiotoxicity and chemical toxicity. Here, a cellulase-producing Penicillium fungus was screened and characterized by X-ray fluorescence (XRF), and Fourier transform infrared reflection (FT-IR), as well as by GC/MS metabolomics analysis, to study the response to uranium(VI) stress. The biomass of Penicillium decreased after exposure to 100 mg/L U. Uranium combined with carboxyl groups, amino groups, and phosphate groups to form uranium mineralized deposits on the surface of this fungal strain. The α-activity concentration of uranium in the strain was 2.57×106 Bq/kg, and the β-activity concentration was 2.27×105 Bq/kg. Metabolomics analysis identified 118 different metabolites, as well as metabolic disruption of organic acids and derivatives. Further analysis showed that uranium significantly affected the metabolism of 9 amino acids in Penicillium. These amino acids were related to the TCA cycle and ABC transporter. At the same time, uranium exhibited nucleotide metabolism toxicity to Penicillium. This study provides an in-depth understanding of the uranium tolerance mechanism of Penicillium and provides a theoretical basis for Penicillium to degrade hyper-enriched plants. 相似文献
24.
Rengasamy Alagarsamy 《Chemistry and Ecology》2013,29(6):419-429
The quantity and biochemical composition of organic matter (OM) in the sediments underlying and below oxygen minimum zone (OMZ) in the Arabian Sea were studied to provide information on the diagenetic processes of organic carbon under different environmental conditions. Concentrations of total organic carbon (TOC), total nitrogen (TN) and total hydrolysable amino acids (THAA) were significantly higher in sediments within rather than below OMZ, while those of total carbohydrates (TCHO) were slightly lower in the latter, suggesting the presence of a larger supply of labile compounds into the sea bottom at the shallower site (i.e. within OMZ). Hydrolysable amino acid and carbohydrate contribution to TOC were even lower (about 10% in surficial sediments) than the values obtained from the abyssal oligotrophic North Pacific, suggesting that OM food availability in the Oman Margin sediments within OMZ was lower than that observed at abyssal depths. The presence of the highest THAA and TCHO concentrations in the top 40?mm of the sediment core at both sites reflected the presence of bioturbation processes. In contrast with the general view of the deep sea as a stable and constant system, below OMZ in the Arabian Sea sediments, some differences were observed in the two investigated cores indicating the presence of a certain spatial variability in OM content and diagenesis. 相似文献
25.
Ying Xue Keke Xiao Xiang Wu Mei Sun Yifei Liu Bei Ou Jiakuan Yang 《Frontiers of Environmental Science & Engineering》2023,17(3):35
26.
27.
Sydney T Bacchus Toshihide Hamazaki Kerry O. Britton Bruce L. Haines 《Journal of the American Water Resources Association》2000,36(1):55-65
ABSTRACT: Pond‐cypress, a deciduous conifer, is a dominant canopy species in depressional wetlands of the southeastern Coastal Plain (SCP). Extensive premature decline and death of pond‐cypress trees in central Florida have been attributed to hydroperiod alterations due to excessive withdrawals of ground water from the Floridan aquifer. One factor identified in the decline process is basal decay, which may be related to the presence of Botryosphaeria rhodina and Fusarium species (nonaggressive, facultative fungal pathogens). These fungi have been cultured from sapwood tissue of declining pond‐cypress associated with ground water mining, but not from pond‐cypress away from ground water mimng areas. In this experiment, differences in soluble (nonstructural) carbohydrate composition of branch tips were evaluated for one‐and two‐year old, nursery‐grown (unsheltered) pond‐cypress, following a year of growth under treatment conditions (control, fungal inoculation, water stress, and fungal inoculation plus water stress) in a growth chamber. Results from two methods of wet chemical analysis were compared (trimethylsilyl methylglycoside‐Method A, and alditol acetate ‐ Method B). Three pentoses (arabinose, rhamnose, and xylose) and three hexoses (galactose, glucose, and mannose) were identified in branch tips from both age classes. A fourth hexose (fucose) also was identified in samples from the younger trees. The acidic sugar, galacturonic acid, was identified in both age classes using Method A. Results suggest that prolonged water stress is correlated with greater relative concentrations of the neutral soluble sugars rhamnose (P = 0.02), xylose (P = 0.02), and galactose (P = 0.02), in addition to the acidic sugar galacturonic acid (P = 0.01), for Method A, and arabinose (P = 0.02) for Method B. These results also suggest that in the absence of water stress, the fungal pathogen B. rhodina does not penetrate to the sapwood of the trees, and that inoculation with this fungal pathogen is not correlated with differences in relative concentrations of nonstructural, soluble carbohydrates, based on Method A analysis. Empirical evidence suggests that pond‐cypress trees in depressional wetlands respond similarly to anthropogenic perturbations of ground water, but not to natural periods of drought in the absence of such perturbations. Therefore, pond‐cypress appear to be integrators of groundwater perturbations. Greater concentrations of the soluble sugars identified in this study in pond‐cypress branch tips may be hydroecological indicators of such anthropogenic perturbations as unsustainable yield from the regional aquifer and adverse impacts from aquifer storage and recovery (ASR) activities in the SCP. 相似文献
28.
采用邻苯二甲醛柱前衍生5种氨基酸,用反向高效液相色谱法测定衍生化产物,通过优化衍生化条件和色谱条件,使该方法在0.25μmol/L~25μmol/L范围内线性良好。方法检出限为0.08μmol/L~0.12μmol/L,标准溶液测定6次的RSD为0.1%~1.2%,空白加标样的回收率为80.3%~115%。用该方法测定实际水样,5种氨基酸测定值均低于0.514μmol/L,加标回收率在75.5%~120%之间。 相似文献
29.
Summary. Induction of secondary metabolites to herbivore damage is a widespread phenomenon among plants and serves to enhance resistance
by reducing suitability or increasing toxicity of foliage. Post-damage responses of primary metabolites are less well known;
reductions in primary metabolites may increase resistance by decreasing palatability or nutritional suitability for herbivores
or by potentiating toxicity of secondary metabolites. In this study, we examined response to simulated herbivory in Pastinaca sativa, the wild parsnip, in both primary and secondary metabolites. We found that induction of secondary metabolites in response
to damage is largely restricted to a single class of compounds, the furanocoumarins. These prooxidant compounds are known
to be toxic to a wide variety of insect herbivores. The only primary metabolite that responded to damage was total soluble
protein, which increased significantly 24 h after damage. After 24 h, the correlation between total furanocoumarins and total
sugars was significant and negative (r = − 0.697). This correlation likely reflects an independent response of sugar to damage,
rather than a diversion of resources into furanocoumarin production, inasmuch as this correlation at 3 h, after furanocoumarin
induction had taken place, was not significant. In other secondary metabolite pathways, damage produced a significant decline
in farnesene and a C-16 unsaturated fatty acid, 7,10,13-hexadecatrienoic acid, each of which may potentiate the furanocoumarin
defense response. Farnesene may enhance photooxidative activation of the furanocoumarins and 7,10,13-hexadecatrienoic acid
may serve as a precursor to jasmonic acid, a key hormone in regulating induction responses. With few key exceptions, quantities
of both primary and secondary metabolites in wild parsnip foliage are unaffected by damage. Those that are affected may well
play a role in resistance of parsnips to herbivores.
Received 1 July 1998; accepted 28 September 1998. 相似文献
30.
Reduced nitrogen has a greater effect than oxidised nitrogen on dry heathland vegetation 总被引:2,自引:0,他引:2
van den Berg LJ Peters CJ Ashmore MR Roelofs JG 《Environmental pollution (Barking, Essex : 1987)》2008,154(3):359-369
We investigated the effects of different ratios of reduced (NH4+) versus oxidised (NO3(-)) nitrogen in deposition on heathland and species-rich grassland vegetation at high nitrogen deposition levels in large mesocosms filled with nutrient-poor soils to which different NH4+/NO3(-) ratios were applied. The response of the forbs, Antennaria dioica, Arnica montana, Gentiana pneumonanthe, Thymus serpyllum, the grasses Danthonia decumbens, Deschampsia flexuosa, Nardus stricta and the shrub Calluna vulgaris was recorded. The forb A. dioica and the grass D.decumbens preferred low NH4+/NO3(-) ratios and were characterised by a negative correlation between NH4+/NO3(-) ratios and biomass and survival, whereas the grasses N. stricta and D. flexuosa showed no correlation with NH4+/NO3(-) ratios. Lime addition eliminated the negative effects of high NH4+ concentrations in deposition for A. dioica and the grass D. decumbens. The implications of these findings for heathland vegetations are discussed. 相似文献