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161.
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Seasonal fluctuation of dehydrins is related to osmotic status in Scots pine needles 总被引:1,自引:0,他引:1
Seasonal variation in dehydrins and other soluble proteins of Scots pine (Pinus sylvestris L.) needles, buds and bark were analyzed monthly for 1 year from 1998 to 1999. Dehydrin-related proteins of 60 and 56 kDa were identified immunologically in all tissues. The concentration of the 60-kDa dehydrin was highest during the winter (October-February) in buds and bark but increased in early spring (March-May) in needles. Accumulation of the 60-kDa dehydrin in the needles in springtime was related to the decreasing osmotic potentials of the needles. The 56-kDa dehydrin was present only during the growing season, as was a 50-kDa dehydrin, which only appeared in bud and bark tissues. The soluble protein concentration of needles did not differ significantly between seasons, but in bark and bud tissues the protein concentrations were at their lowest level in newly grown tissues (June-August). The level of several polypeptides was higher during the winter-spring period than in the growing season, especially in bark and bud tissues. These proteins may be related to cold hardiness or dormancy in overwintering Scots pine. Dehydrin-related proteins in needles are linked to springtime changes in the osmotic status of needles rather than to their cold acclimation. 相似文献
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E Taulavuori E K Hellstr?m K Taulavuori K Laine 《Journal of experimental botany》2001,52(365):2375-2380
Malondialdehyde (MDA) concentration is a widely used method to analyse lipid peroxidation in biological material. In plant tissues, however, certain compounds (anthocyanins, carbohydrates) may interfere with measurements which may lead to an overestimation of the MDA levels. Two methods were compared for analysing lipid peroxidation, either uncorrected or corrected for interfering compounds. The comparison was performed in three separate experiments with respect to cold treatments (snow removal in winter, reacclimation in summer and cold acclimation in autumn) in bilberry (Vaccinium myrtillus L.). During winter and autumn the methods seem to measure different compounds, but during active growth in the summer the difference between the methods was less. This is obviously due to carbohydrates which act as cryoprotectants and increase in concentration during cold acclimation as well as due to the anthocyanins. It is thus suggested that the validity of the uncorrected method to measure MDA and thereby lipid peroxidation is best in plant tissue which is in an active growth state. 相似文献
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We investigated the relations among 83 hydrologic condition metrics (HCMs) and changes in algal, invertebrate, and fish communities
in five metropolitan areas across the continental United States. We used a statistical approach that employed Spearman correlation
and regression tree analysis to identify five HCMs that are strongly associated with observed biological variation along a
gradient of urbanization. The HCMs related to average flow magnitude, high-flow magnitude, high-flow event frequency, high-flow
duration, and rate of change of stream cross-sectional area were most consistently associated with changes in aquatic communities.
Although our investigation used an urban gradient design with short hydrologic periods of record (≤1 year) of hourly cross-sectional
area time series, these five HCMs were consistent with previous investigations using long-term daily-flow records. The ecological
sampling day often was included in the hydrologic period. Regression tree models explained up to 73, 92, and 79% of variance
for specific algal, invertebrate, and fish community metrics, respectively. National models generally were not as statistically
significant as models for individual metropolitan areas. High-flow event frequency, a hydrologic metric found to be transferable
across stream type and useful for classifying habitat by previous research, was found to be the most ecologically relevant
HCM; transformation by precipitation increased national-scale applicability. We also investigated the relation between measures
of stream flashiness and land-cover indicators of urbanization and found that land-cover characteristic and pattern variables,
such as road density, percent wetland, and proximity of developed land, were strongly related to HCMs at both a metropolitan
and national scale and, therefore, may be effective land-use management options in addition to wholesale impervious-area reduction. 相似文献
168.
We developed primers for five polymorphic microsatellite loci to analyse the genetic structure of colonies in an invading Argentine ant population located in Haleakala National Park on the island of Maui, Hawaii. Microsatellite loci were isolated using both a polymerase chain reaction‐based and a cloning‐based method. With a range of 3–18 alleles and expected levels of heterozygosity of 0.46–0.77, these loci provide useful markers for the detection of colony and population structure in new or expanding populations of this species. 相似文献
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Effect of migration and environmental heterogeneity on the maintenance of quantitative genetic variation: a simulation study
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The paradox of high genetic variation observed in traits under stabilizing selection is a long‐standing problem in evolutionary theory, as mutation rates appear too low to explain observed levels of standing genetic variation under classic models of mutation–selection balance. Spatially or temporally heterogeneous environments can maintain more standing genetic variation within populations than homogeneous environments, but it is unclear whether such conditions can resolve the above discrepancy between theory and observation. Here, we use individual‐based simulations to explore the effect of various types of environmental heterogeneity on the maintenance of genetic variation (VA) for a quantitative trait under stabilizing selection. We find that VA is maximized at intermediate migration rates in spatially heterogeneous environments and that the observed patterns are robust to changes in population size. Spatial environmental heterogeneity increased variation by as much as 10‐fold over mutation–selection balance alone, whereas pure temporal environmental heterogeneity increased variance by only 45% at max. Our results show that some combinations of spatial heterogeneity and migration can maintain considerably more variation than mutation–selection balance, potentially reconciling the discrepancy between theoretical predictions and empirical observations. However, given the narrow regions of parameter space required for this effect, this is unlikely to provide a general explanation for the maintenance of variation. Nonetheless, our results suggest that habitat fragmentation may affect the maintenance of VA and thereby reduce the adaptive capacity of populations. 相似文献