1,721,095 research outputs found
Age-dependent tree-ring growth responses to climate in Larix decidua and Pinus cembra
No full textDendrochronology generally operates under the assumption that climate–
growth relationships are age independent, once growth trends and/or disturbance pulses
have been accounted for. However, several studies have demonstrated that tree physiology
undergoes changes with age. This may cause growth-related climate signals to vary over
time. Using chronology statistics and response functions, we tested the consistency of
climate–growth responses in tree-ring series from Larix decidua and Pinus cembra trees
of four age classes. Tree-ring statistics (mean sensitivity, standard deviation, correlation
between trees, and first principal component) did not change significantly with age in P.
cembra, whereas in L. decidua they appeared to be correlated with age classes. Response
function analysis indicated that climate accounts for a high amount of variance in tree-ring
widths in both species. The older the trees are, the higher the variance explained by climate,
the significance of the models, and the percentage of trees with significant responses.
Age influence on climate sensitivity is likely to be non-monotonic. In L. decidua, the
most important response function variables changed with age according to a twofold pattern:
increasing for trees younger than 200 years and decreasing or constant for older trees. A
similar pattern was observed in both species for the relationship between tree height and
age. It is hypothesized that an endogenous parameter linked to hydraulic status becomes
increasingly limiting as trees grow and age, inducing more stressful conditions and a higher
climate sensitivity in older individuals.
The results of this study confirm that the climate signal is maximized in older trees,
but also that a sampling procedure non-stratified by age (especially in multi-aged forests)
could lead to biased mean chronologies due to the higher amount of noise present in younger
trees. The issue requires more extensive research as there are important ecological implications
both at small and large geographic scales. Predictive modeling of forest dynamics
and paleo-climate reconstructions may be less robust if the age effect is not accounted for
Spatial analysis of structural and tree-ring related parameters in a timberline forest in the Italian Alps
No full text
Assetto strutturale e qualità dei fusti - Studio su cedui di faggio in conversione in un parco nazionale
No full textIn three sites correspondent to different steps of the conversion process (abandoned coppice, stands with first and second thinning) we have measured forest structure and assessed timber quality of stems. The vertical structure is very similar in the three sites, but stem domages increase with the number of thinnings. Current management does not seem suitable both timber supply (mainly fuelwood) and nature conservation
Dinamismo spaziale e cronologico di Juniperus communis L., in campi abbandonati nelle prealpi orientali
No full textDating and explanation of Late Glacial – Holocene landslides: a case study from the Southern Alps
No full textLandslide chronologies are essential both for understanding the causes of mass movements and for the assessment of landslide hazards. The Fadalto landslide (Venetian Prealps, Italy) studied in this paper has been active, as shown by morphological and stratigraphical data, for several thousands years since the Late Glacial. The chronology of this large and complex landslide was significantly improved through identification and radiocarbon and dendrochronological dating of several mass movements which occurred during the Holocene: one in the late Atlantic (5375 ± 95 years BP) and others in historical times (within the last 14 centuries). Understanding the specific causes of these landslides, and establishing a relationship between landslides and climate (or earthquakes) in particular turned out to be a difficult task (mainly due to the imprecision of radiocarbon dating). It can not be ruled out that the landslides occurred under colder and more changeable climate or during a transition between climatic spells with different characteristics. Dendrochronological analyses, on the other hand, show no relationship between one of these historical landslides and climate (or earthquakes). Reactivations of movements involved both the main scarp and the accumulation zone; besides, it was recognised that the landslide can be reactivated through a rock avalanche, a type of complex landsliding not uncommon in the southern Alps
Corrigendum to “Structural attributes, tree-ring growth and climate sensitivity of Pinus nigra Arn. at high altitude: Common patterns of a possible treeline shift in the central Apennines (Italy)” [Dendrochronologia 32 (3) (2014) 210–219](S1125786514000502)(10.1016/j.dendro.2014.05.002)
No full textThe authors regret The authors would like to apologise for any inconvenience caused
Rescuing defective CFTR applying a drug repositioning strategy based on computational studies, surface plasmon resonance and cell-based assays
No full textCystic Fibrosis (CF) is caused by mutations (mainly F508del) of the
cystic fibrosis transmembrane conductance regulator (CFTR). Current
CF therapies are aimed at symptoms alleviation, calling for new
drugs to rescue CFTR function.
Hypothesis and objectives
Drug repositioning is aimed at finding new applications for already
marketed drugs, reducing cost and duration and the likelihood of
unforeseen adverse events. In this project we have integrated drug
repositioning with computational studies, surface plasmon resonance
(SPR) [1] and well-tried cellular models [2] to identify new CF drugs
and to comprehend their mechanism of action.
Methods and results
We have prepared a new structural homology model of intact human
F508del-CFTR embedded in a phospholipid bilayer and a SPR biosensor
containing the same protein in a cell membrane-mimicking lipid
film.
These tools, along with appropriate cell-based assays, have been
firstly used to analyze a mixed library of well-known and new compounds
that allowed the validation of the system and the identification
of a promising molecule endowed with a F508del-binding and
rescuing capacity that is higher than those of drugs already in use.
With the computational model we have then performed a virtual
drug repositioning on a library of 846 drugs, identifying 10 drugs
that were reduced to 4 on the basis of toxicity profile and patient
compliance. These drugs will be now subjected to experimental analysis
by cell-based and SPR assays for their effective capacity to bind
F508del-CFTR and rescue its activity. Also, we will proceed to the virtual
repositioning of a library of natural compounds.
Spin-off for research & clinical purposes
The novel computational models and biosensors will widen the study
of CF drugs and made available to other research groups in the field
of CF.
References
1. Rusnati M, Sala D, Orro A, Bugatti A, Trombetti G, Cichero E, Urbinati C,
Di Somma M, Millo E, Galietta LJV, Milanesi L, Fossa P, D'Ursi P. Speeding
Up the Identification of Cystic Fibrosis Transmembrane Conductance
Regulator-Targeted Drugs: An Approach Based on Bioinformatics Strategies
and Surface Plasmon Resonance. Molecules. 2018 Jan 8;23(1). pii:
E120. doi: 10.3390/molecules23010120.
2. Tomati V, Pesce E, Caci E, Sondo E, Scudieri P, Marini M, Amato F,
Castaldo G, Ravazzolo R, Galietta LJV, Pedemonte N. High-throughput
screening identifies FAU protein as a regulator of mutant cystic fibrosis
transmembrane conductance regulator channel. J Biol Chem. 2018 Jan
26;293(4):1203-1217. doi: 10.1074/jbc.M117.816595. Epub 2017 Nov 20.
Acknowledgment FFC#11/2018 funded by FFC and supported by Delegazione
FFC di Torin
Testing for tree-ring divergence in the European Alps
No full textEvidence for reduced sensitivity of tree growth to temperature has been reported from
multiple forests along the high northern latitudes. This alleged circumpolar phenomenon
described the apparent inability of temperature-sensitive tree-ring width and density
chronologies to parallel increasing instrumental temperature measurements since the
mid-20th century. In addition to such low-frequency trend offset, the inability of
formerly temperature-sensitive tree growth to reflect high-frequency temperature signals
in a warming world is indicated at some boreal sites, mainly in Alaska, the Yukon and
Siberia. Here, we refer to both of these findings as the ‘divergence problem’ (DP), with
their causes and scale being debated. If DP is widespread and the result of climatic
forcing, the overall reliability of tree-ring-based temperature reconstructions should be
questioned. Testing for DP benefits from well-replicated tree-ring and instrumental data
spanning from the 19th to the 21st century. Here, we present a network of 124 larch and
spruce sites across the European Alpine arc. Tree-ring width chronologies from 40 larch
and 24 spruce sites were selected based on their correlation with early (1864–1933)
instrumental temperatures to assess their ability of tracking recent (1934–2003) temperature
variations. After the tree-ring series of both species were detrended in a manner that
allows low-frequency variations to be preserved and scaled against summer temperatures,
no unusual late 20th century DP is found. Independent tree-ring width and density
evidence for unprecedented late 20th century temperatures with respect to the past
millennium further reinforces our results
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