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H. Blondeel M. P. Perring E. De Lombaerde L. Depauw D. Landuyt S. Govaert S. L. Maes P. Vangansbeke P. De Frenne K. Verheyen 《Plant biology (Stuttgart, Germany)》2020,22(4):601-614
- Intraspecific trait variation (ITV; i.e. variability in mean and/or distribution of plant attribute values within species) can occur in response to multiple drivers. Environmental change and land‐use legacies could directly alter trait values within species but could also affect them indirectly through changes in vegetation cover. Increasing variability in environmental conditions could lead to more ITV, but responses might differ among species. Disentangling these drivers on ITV is necessary to accurately predict plant community responses to global change.
- We planted herb communities into forest soils with and without a recent history of agriculture. Soils were collected across temperate European regions, while the 15 selected herb species had different colonizing abilities and affinities to forest habitat. These mesocosms (384) were exposed to two‐level full‐factorial treatments of warming, nitrogen addition and illumination. We measured plant height and specific leaf area (SLA).
- For the majority of species, mean plant height increased as vegetation cover increased in response to light addition, warming and agricultural legacy. The coefficient of variation (CV) for height was larger in fast‐colonizing species. Mean SLA for vernal species increased with warming, while light addition generally decreased mean SLA for shade‐tolerant species. Interactions between treatments were not important predictors.
- Environmental change treatments influenced ITV, either via increasing vegetation cover or by affecting trait values directly. Species’ ITV was individualistic, i.e. species responded to different single resource and condition manipulations that benefited their growth in the short term. These individual responses could be important for altered community organization after a prolonged period.
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Libo Tan Amanda E. Wray Michael H. Green A. Catharine Ross 《Journal of lipid research》2014,55(6):1077-1086
Vitamin A (VA) metabolism in neonates is virtually uncharacterized. Our objective was to develop a compartmental model of VA metabolism in unsupplemented and VA-supplemented neonatal rats. On postnatal day 4, pups (n = 3/time) received 11,12-[3H]retinol orally, in either oil (control) or VA combined with retinoic acid (VARA) [VA (∼6 mg/kg body weight) + 10% retinoic acid]. Plasma and tissues were collected at 14 time points up to 14 days after dose administration. VARA supplementation rapidly, but transiently, increased total retinol mass in plasma, liver, and lung. It decreased the peak fraction of the dose in plasma. A multi-compartmental model developed to fit plasma [3H]retinol data predicted more extensive recycling of retinol between plasma and tissues in neonates compared with that reported in adults (144 vs. 12–13 times). In VARA pups, the recycling number for retinol between plasma and tissues (100 times) and the time that retinol spent in plasma were both lower compared with controls; VARA also stimulated the uptake of plasma VA into extravascular tissues. A VARA perturbation model indicated that the effect of VARA in stimulating VA uptake into tissues in neonates is both dramatic and transient. 相似文献
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Julia E. Maxson Samuel B. Luty Jason D. MacManiman Melissa L. Abel Brian J. Druker Jeffrey W. Tyner 《The Journal of biological chemistry》2014,289(9):5820-5827
Mutations in the CSF3 granulocyte colony-stimulating factor receptor CSF3R have recently been found in a large percentage of patients with chronic neutrophilic leukemia and, more rarely, in other types of leukemia. These CSF3R mutations fall into two distinct categories: membrane-proximal mutations and truncation mutations. Although both classes of mutation have exhibited the capacity for cellular transformation, several aspects of this transformation, including the kinetics, the requirement for ligand, and the dysregulation of downstream signaling pathways, have all been shown to be discrepant between the mutation types, suggesting distinct mechanisms of activation. CSF3R truncation mutations induce overexpression and ligand hypersensitivity of the receptor, likely because of the removal of motifs necessary for endocytosis and degradation. In contrast, little is known about the mechanism of activation of membrane-proximal mutations, which are much more commonly observed in chronic neutrophilic leukemia. In contrast with CSF3R truncation mutations, membrane-proximal mutations do not exhibit overexpression and are capable of signaling in the absence of ligand. We show that the Thr-615 and Thr-618 sites of membrane-proximal mutations are part of an O-linked glycosylation cluster. Mutation at these sites prevents O-glycosylation of CSF3R and increases receptor dimerization. This increased dimerization explains the ligand-independent activation of CSF3R membrane-proximal mutations. Cytokine receptor activation through loss of O-glycosylation represents a novel avenue of aberrant signaling. Finally, the combination of the CSF3R membrane proximal and truncation mutations, as has been reported in some patients, leads to enhanced cellular transformation when compared with either mutation alone, underscoring their distinct mechanisms of action. 相似文献
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Current MR methods use T2? relaxation time as a surrogate measure of ligament strength. Currently, a multi-echo voxel-wise least squares fit is the gold standard to create T2? maps; however, the post-processing is time-intensive and serves as a stopgap for clinical use. The study objective was to determine if an alternative method could improve post-processing time without sacrificing fidelity of T2? values for eventual translational use in the clinic. Using a 6 echo FLASH sequence, three different methods were used to determine intact posterior cruciate ligament (PCL) median T2? Two of these methods utilized a voxel-wise method to establish T2? maps: (1) a current “gold standard” method using a voxel-wise 6 echo least-squares fit (6LS) and (2) a voxel-wise 2 echo point T2? determination (2MM). The third method used median ligament signal intensity and a single nonlinear least-squares fit (6LSROI) instead of a voxel-wise basis. The resulting median T2? values of the PCL and computational time were compared. The median T2? values were 42% higher using the 2MM compared to the 6LS method (p<0.0001). However, a strong correlation was found for the median T2? values between the 2MM and 6LS methods (R2=0.80). The median T2? values were not significantly different between the 6LS and 6LSROI methods (p=0.519). Using the 2MM (which provides a regional map) and the 6LSROI (which efficiently provides the median T2? value) methods in tandem would take only minutes of post-processing computational time compared to the 6LS method (~540 min), and hence would facilitate clinical application of T2? maps to predict ligament structural properties as a patient outcome measure. 相似文献