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91.
Iris pseudacorus L. has been widely used in aquatic ecosystem to remove nutrient and has achieved positive effects. However, little is known regarding the nutrient-removal performance and physiological responses of I. pseudacorus for brackish eutrophic water treatment due to high nutrients combined with certain salinity levels. In this study, I. pseudacorus-planted microcosms were established to evaluate the capacity of I. pseudacorus to remove excessive nutrients from fresh (salinity 0.05%) and brackish (salinity 0.5%) eutrophic waters. The degradation of total nitrogen and ammonia nitrogen were not affected by 0.5% salinity; 0.5% salinity promoted the degradation of nitrate nitrogen while severely inhibited the degradation of total phosphorus. Additionally, 0.5% salinity was found to induce stress responses quantified by measuring six physiological indexes. Compared to 0.05% salinity, 0.5% salinity resulted in significant decreases in the chlorophyll a, b and total chlorophyll contents of I. pseudacorus which closely related to photosynthesis (p < 0.05). Furthermore, the higher proline, malondialdehyde contents and antioxidant enzyme activities were detected in I. pseudacorus exposed to 0.5% salinity, which provided protection against reactive oxygen species. The results highlight that the cellular stress assays are efficient for monitoring the health of I. pseudacorus in salinity shock-associated constructed wetlands. 相似文献
92.
Hypoxia is associated with many pathological conditions as well as the normal physiology of metazoans. We identified a lactate-dependent signaling pathway in hypoxia, mediated by the oxygen- and lactate-regulated protein NDRG family member 3 (NDRG3). Oxygen negatively regulates NDRG3 expression at the protein level via the PHD2/VHL system, whereas lactate, produced in excess under prolonged hypoxia, blocks its proteasomal degradation by binding to NDRG3. We also found that the stabilized NDRG3 protein promotes angiogenesis and cell growth under hypoxia by activating the Raf-ERK pathway. Inhibiting cellular lactate production abolishes NDRG3-mediated hypoxia responses. The NDRG3-Raf-ERK axis therefore provides the genetic basis for lactate-induced hypoxia signaling, which can be exploited for the development of therapies targeting hypoxia-induced diseases in addition to advancing our understanding of the normal physiology of hypoxia responses. [BMB Reports 2015; 48(6): 301-302] 相似文献
93.
Tzu‐Ying Wang Jin‐Bin Wu Tsong‐Long Hwang Yueh‐Hsiung Kuo Jih‐Jung Chen 《化学与生物多样性》2010,7(7):1828-1834
The fruit of Tetradium ruticarpum is widely used in healthcare products for the improvement of blood circulation, headache, abdominal pain, amenorrhea, chill limbs, migraine, and nausea. A new quinolone, 2‐[(6Z,9Z)‐pentadeca‐6,9‐dienyl]quinolin‐4(1H)‐one ( 1 ), has been isolated from the fruits of T. ruticarpum, together with eleven known compounds. The structure of the new compound was determined by NMR and MS analyses. Rutaecarpine ( 4 ), evodiamine ( 5 ), and skimmianine ( 7 ) exhibited inhibition (IC50≤20.9 μM ) of O$\rm{{_{2}^{{^\cdot} -}}}$ generation by human neutrophils in response to N‐formyl‐L ‐methionyl‐L ‐leucyl‐L ‐phenylalanine/cytochalasin B (fMLP/CB). In addition, 1 , evocarpine ( 2 ), 4, 7 , and evodol ( 8 ) inhibited fMLP/CB‐induced elastase release with IC50 values ≤14.4 μM . 相似文献
94.
Summary . We consider analysis of clustered data with mixed bivariate responses, i.e., where each member of the cluster has a binary and a continuous outcome. We propose a new bivariate random effects model that induces associations among the binary outcomes within a cluster, among the continuous outcomes within a cluster, between a binary outcome and a continuous outcome from different subjects within a cluster, as well as the direct association between the binary and continuous outcomes within the same subject. For the ease of interpretations of the regression effects, the marginal model of the binary response probability integrated over the random effects preserves the logistic form and the marginal expectation of the continuous response preserves the linear form. We implement maximum likelihood estimation of our model parameters using standard software such as PROC NLMIXED of SAS . Our simulation study demonstrates the robustness of our method with respect to the misspecification of the regression model as well as the random effects model. We illustrate our methodology by analyzing a developmental toxicity study of ethylene glycol in mice. 相似文献
95.
Summary A class of nonignorable models is presented for handling nonmonotone missingness in categorical longitudinal responses. This class of models includes the traditional selection models and shared parameter models. This allows us to perform a broader than usual sensitivity analysis. In particular, instead of considering variations to a chosen nonignorable model, we study sensitivity between different missing data frameworks. An appealing feature of the developed class is that parameters with a marginal interpretation are obtained, while algebraically simple models are considered. Specifically, marginalized mixed‐effects models ( Heagerty, 1999 , Biometrics 55, 688–698) are used for the longitudinal process that model separately the marginal mean and the correlation structure. For the correlation structure, random effects are introduced and their distribution is modeled either parametrically or non‐parametrically to avoid potential misspecifications. 相似文献
96.
Studying global change through investigation of the plastic responses of xylem anatomy in tree rings 总被引:1,自引:0,他引:1
Patrick Fonti Georg von Arx Ignacio García-González Britta Eilmann Ute Sass-Klaassen Holger Gärtner Dieter Eckstein 《The New phytologist》2010,185(1):42-53
Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach. 相似文献
97.
Water use efficiency of twenty-five co-existing Patagonian species growing under different soil water availability 总被引:2,自引:0,他引:2
The variation of plant water use efficiency (WUE) with water availability has two interacting components: a plastic response,
evident when individuals of the same genotype are compared (e.g. wet versus dry years), and an interspecific response, evident
when different species living in habitats with different water availability are compared. We analysed the WUE of 25 Patagonian
species that belong to four life forms (grasses, shrubs, annual herbs and perennial herbs) in relation to the climatic conditions
of 2 years and the mean historic water availability experienced by each species. To estimate water availability, we calculated
the effective soil water potential (EWP) of each species, based on available information about soil water dynamics, phenology
and root system structure. To estimate WUE, we used isotopic discrimination of leaf C (Δ13C) and mean annual water vapour difference between leaves and atmosphere (Δe) measured in situ. For the plastic response, for every species and life form, WUE increased from the dry to the wet year.
We hypothesize that photosynthesis was less nutrient limited in the wet than in the dry year, facilitating higher net photosynthesis
rates per unit of stomatal conductance in the wet year. For the interspecific response, WUE was lower in species native to
drier habitats than in species native to wetter habitats. This response was mostly accounted for by a decrease in Δe with EWP. Annual herbs, which avoid drought in time (they have the earliest growth cycle), and shrubs, which avoid drought
in space (they have the deepest roots), showed the highest EWP and WUE. We conclude that the conventional wisdom which states
that the highest WUE occurs within a species during the driest years, and among species in the driest habitats, does not always
hold true, and that co-existing life forms drastically differ in water availability and water economy. 相似文献
98.
Jeschke JM 《Oecologia》2007,152(2):357-364
Are animals usually hungry and busily looking for food, or do they often meet their energetic and other needs in the 24 h of a day? Focusing on carnivores, I provide evidence for the latter scenario. I develop a model that predicts the minimum food abundance at which a carnivore reaches satiation and is released from time constraints. Literature data from five invertebrate and vertebrate species suggest that food abundances experienced in the field often exceed this threshold. A comparison of energetic demands to kill rates also suggests that carnivores often reach satiation: for the 16 bird and mammal species analyzed, this frequency is 88% (average across species). Because pressure of time would likely lead to trade-offs in time allocation and thus to a nonsatiating food consumption, these results suggest that carnivores are often released from time constraints. 相似文献
99.
* Increasing climatic unpredictability associated with characteristics of some species makes plant drought-tolerance an important drought-adaptation strategy. Using norm-of-reaction functions, or empirically determined functions that enable us to predict the state of a trait given the state of an environmental variable, allows modelling of plant performance when water availability varies randomly. * A mathematical model is proposed to evaluate drought-tolerance and growth strategies given a set of environmental parameters: the frequency of rainy days, the soil water-storage capacity, plant water use and plant growth rates. This model compares the performance of genotypes that differ in drought tolerance expressed as the ability to grow in drier soils, and assumes a general trade-off function between drought tolerance and maximum plant growth rate. * It is worth selecting plants with a greater degree of drought tolerance, expressed by the ability to grow in drier soils whenever the frequency of rains is smaller than the rate of soil water depletion. Otherwise, maximizing growth rate at the expense of drought tolerance is the best strategy. The nature of the trade-off between drought tolerance and plant growth rate also constrains the selection for optimal drought-adapted genotypes. * Breeders will have to consider these aspects of plant-environment interactions before establishing selection programs for drought adaptation. 相似文献
100.
Leaf wounding and the wound signaling peptide systemin induce expression of wound response genes while the fungal toxin fusicoccin
(FC) induces expression of pathogenesis-related genes. Consistent with their functional differences, FC and systemin regulate
the extracellular pH in opposite ways, with systemin inducing an alkalinization and FC an acidification response. Here we
show that systemin, wounding and FC activate the same mitogen-activated protein kinases (MAPKs; MPKs) MPK1 and 2 in tomato
(Lycopersicon esculentum) leaves and L. peruvianum suspension-cultured cells. Wounding and FC activated an additional MAPK, MPK3. Pronounced differences were observed with
regard to MAPK activation kinetics. FC induced prolonged, and systemin transient activity of the MAPKs. This shows that functionally
different elicitors engage the same signaling components, yet induce signal-specific activation dynamics. A comparative analysis
of pH effects and MAPK activity in response to specific treatments revealed that the kinetics of pH changes and MAPK activation
did not correlate. Simultaneous application of FC and systemin did not lead to immediate pH changes but resulted in rapid
increases in MAPK activity. Furthermore, changes in extracellular pH could be induced without concomitant MAPK activation
by exchanging conditioned medium with fresh medium. This shows that changes in the extracellular pH are neither required nor
sufficient for MAPK activation, suggesting that signaling pathways involving MAPKs and extracellular pH changes operate in
parallel and are not part of the same linear pathway. 相似文献