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1.
Glob Chang Biol ; 28(24): 7376-7390, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36200354

RESUMO

Global warming is pushing populations outside their range of physiological tolerance. According to the environmental envelope framework, the most vulnerable populations occur near the climatic edge of their species' distributions. In contrast, populations from the climatic center of the species range should be relatively buffered against climate warming. We tested this latter prediction using a combination of linear mixed effects and machine learning algorithms on an extensive, citizen-scientist generated dataset on the fruitbody productivity of the Burgundy (aka summer) truffle (Tuber aestivum Vittad.), a keystone, ectomycorrhizal tree-symbiont occurring on a wide range of temperate climates. T. aestivum's fruitbody productivity was monitored at 3-week resolution over up to 8 continuous years at 20 sites distributed in the climatic center of its European distribution in southwest Germany and Switzerland. We found that T. aestivum fruitbody production is more sensitive to summer drought than would be expected from the breadth of its species' climatic niche. The monitored populations occurring nearly 5°C colder than the edge of their species' climatic distribution. However, interannual fruitbody productivity (truffle mass year-1 ) fell by a median loss of 22% for every 1°C increase in summer temperature over a site's 30-year mean. Among the most productive monitored populations, the temperature sensitivity was even higher, with single summer temperature anomalies of 3°C sufficient to stop fruitbody production altogether. Interannual truffle productivity was also related to the phenology of host trees, with ~22 g less truffle mass for each 1-day reduction in the length of the tree growing season. Increasing summer drought extremes are therefore likely to reduce fruiting among summer truffle populations throughout Central Europe. Our results suggest that European T. aestivum may be a mosaic of vulnerable populations, sensitive to climate-driven declines at lower thresholds than implied by its species distribution model.


Assuntos
Ascomicetos , Micorrizas , Estações do Ano , Ascomicetos/fisiologia , Micorrizas/fisiologia , Árvores , Europa (Continente)
2.
Pflugers Arch ; 473(12): 1899-1910, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34564739

RESUMO

In chronic kidney disease (CKD), hyperphosphatemia promotes medial vascular calcification, a process augmented by osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs). VSMC function is regulated by sympathetic innervation, and these cells express α- and ß-adrenergic receptors. The present study explored the effects of ß2-adrenergic stimulation by isoproterenol on VSMC calcification. Experiments were performed in primary human aortic VSMCs treated with isoproterenol during control or high phosphate conditions. As a result, isoproterenol dose dependently up-regulated the expression of osteogenic markers core-binding factor α-1 (CBFA1) and tissue-nonspecific alkaline phosphatase (ALPL) in VSMCs. Furthermore, prolonged isoproterenol exposure augmented phosphate-induced calcification of VSMCs. Isoproterenol increased the activation of PKA and CREB, while knockdown of the PKA catalytic subunit α (PRKACA) or of CREB1 genes was able to suppress the pro-calcific effects of isoproterenol in VSMCs. ß2-adrenergic receptor silencing or inhibition with the selective antagonist ICI 118,551 blocked isoproterenol-induced osteogenic signalling in VSMCs. The present observations imply a pro-calcific effect of ß2-adrenergic overstimulation in VSMCs, which is mediated, at least partly, by PKA/CREB signalling. These observations may support a link between sympathetic overactivity in CKD and vascular calcification.


Assuntos
Adrenérgicos/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Transdução de Sinais/fisiologia , Calcificação Vascular/metabolismo , Aorta/metabolismo , Cálcio/metabolismo , Transdiferenciação Celular/fisiologia , Células Cultivadas , Humanos , Osteogênese/fisiologia , Fosfatos/metabolismo , Insuficiência Renal Crônica/metabolismo
3.
New Phytol ; 232(2): 537-550, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34235742

RESUMO

Microclimatic effects (light, temperature) are often neglected in phenological studies and little information is known about the impact of resource availability (nutrient and water) on tree's phenological cycles. Here we experimentally studied spring and autumn phenology in four temperate trees in response to changes in bud albedo (white-painted vs black-painted buds), light conditions (nonshaded vs c. 70% shaded), water availability (irrigated, control and reduced precipitation) and nutrients (low vs high availability). We found that higher bud albedo or shade delayed budburst (up to +12 d), indicating that temperature is sensed locally within each bud. Leaf senescence was delayed by high nutrient availability (up to +7 d) and shade conditions (up to +39 d) in all species, except oak. Autumn phenological responses to summer droughts depended on species, with a delay for cherry (+7 d) and an advance for beech (-7 d). The strong phenological effects of bud albedo and light exposure reveal an important role of microclimatic variation on phenology. In addition to the temperature and photoperiod effects, our results suggest a tight interplay between source and sink processes in regulating the end of the seasonal vegetation cycle, which can be largely influenced by resource availability (light, water and nutrients).


Assuntos
Fagus , Árvores , Mudança Climática , Folhas de Planta , Estações do Ano , Plântula , Temperatura
4.
Clin Sci (Lond) ; 135(3): 515-534, 2021 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-33479769

RESUMO

In chronic kidney disease (CKD), hyperphosphatemia is a key factor promoting medial vascular calcification, a common complication associated with cardiovascular events and high mortality. Vascular calcification involves osteo-/chondrogenic transdifferentiation of vascular smooth muscle cells (VSMCs), but the complex signaling events inducing pro-calcific pathways are incompletely understood. The present study investigated the role of acid sphingomyelinase (ASM)/ceramide as regulator of VSMC calcification. In vitro, both, bacterial sphingomyelinase and phosphate increased ceramide levels in VSMCs. Bacterial sphingomyelinase as well as ceramide supplementation stimulated osteo-/chondrogenic transdifferentiation during control and high phosphate conditions and augmented phosphate-induced calcification of VSMCs. Silencing of serum- and glucocorticoid-inducible kinase 1 (SGK1) blunted the pro-calcific effects of bacterial sphingomyelinase or ceramide. Asm deficiency blunted vascular calcification in a cholecalciferol-overload mouse model and ex vivo isolated-perfused arteries. In addition, Asm deficiency suppressed phosphate-induced osteo-/chondrogenic signaling and calcification of cultured VSMCs. Treatment with the functional ASM inhibitors amitriptyline or fendiline strongly blunted pro-calcific signaling pathways in vitro and in vivo. In conclusion, ASM/ceramide is a critical upstream regulator of vascular calcification, at least partly, through SGK1-dependent signaling. Thus, ASM inhibition by repurposing functional ASM inhibitors to reduce the progression of vascular calcification during CKD warrants further study.


Assuntos
Transdiferenciação Celular , Proteínas Imediatamente Precoces/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Esfingomielina Fosfodiesterase/farmacologia , Calcificação Vascular/patologia , Amitriptilina/farmacologia , Animais , Células Cultivadas , Ceramidas/metabolismo , Condrogênese/efeitos dos fármacos , Fendilina/farmacologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Fosfatos/farmacologia
5.
Plant Cell Environ ; 43(5): 1288-1299, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31990067

RESUMO

Long generation times have been suggested to hamper rapid genetic adaptation of organisms to changing environmental conditions. We examined if environmental memory of the parental Scots pines (Pinus sylvestris L.) drive offspring survival and growth. We used seeds from trees growing under naturally dry conditions (control), irrigated trees (irrigated from 2003 to 2016), and formerly irrigated trees ("irrigation stop"; irrigated from 2003-2013; control condition since 2014). We performed two experiments, one under controlled greenhouse conditions and one at the experimental field site. In the greenhouse, the offspring from control trees exposed regularly to drought were more tolerant to hot-drought conditions than the offspring from irrigated trees and showed lower mortality even though there was no genetic difference. However, under optimal conditions (high water supply and full sunlight), these offspring showed lower growth and were outperformed by the offspring of the irrigated trees. This different offspring growth, with the offspring of the "irrigation-stop" trees showing intermediate responses, points to the important role of transgenerational memory for the long-term acclimation of trees. Such memory effects, however, may be overridden by climatic extremes during germination and early growth stages such as the European 2018 mega-drought that impacted our field experiment.


Assuntos
Adaptação Fisiológica/fisiologia , Pinus sylvestris/fisiologia , Aclimatação/fisiologia , Meio Ambiente , Germinação/fisiologia , Sementes/fisiologia , Estresse Fisiológico
6.
Glob Chang Biol ; 26(12): 7173-7185, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32786128

RESUMO

Soil nitrogen (N) availability is critical for grassland functioning. However, human activities have increased the supply of biologically limiting nutrients, and changed the density and identity of mammalian herbivores. These anthropogenic changes may alter net soil N mineralization (soil net Nmin ), that is, the net balance between N mineralization and immobilization, which could severely impact grassland structure and functioning. Yet, to date, little is known about how fertilization and herbivore removal individually, or jointly, affect soil net Nmin across a wide range of grasslands that vary in soil and climatic properties. Here we collected data from 22 grasslands on five continents, all part of a globally replicated experiment, to assess how fertilization and herbivore removal affected potential (laboratory-based) and realized (field-based) soil net Nmin . Herbivore removal in the absence of fertilization did not alter potential and realized soil net Nmin . However, fertilization alone and in combination with herbivore removal consistently increased potential soil net Nmin. Realized soil net Nmin , in contrast, significantly decreased in fertilized plots where herbivores were removed. Treatment effects on potential and realized soil net Nmin were contingent on site-specific soil and climatic properties. Fertilization effects on potential soil net Nmin were larger at sites with higher mean annual precipitation (MAP) and temperature of the wettest quarter (T.q.wet). Reciprocally, realized soil net Nmin declined most strongly with fertilization and herbivore removal at sites with lower MAP and higher T.q.wet. In summary, our findings show that anthropogenic nutrient enrichment, herbivore exclusion and alterations in future climatic conditions can negatively impact soil net Nmin across global grasslands under realistic field conditions. This is an important context-dependent knowledge for grassland management worldwide.


Assuntos
Nitrogênio , Solo , Animais , Ecossistema , Fertilização , Pradaria , Herbivoria , Humanos , Nitrogênio/análise
7.
Int J Mol Sci ; 21(19)2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-33003561

RESUMO

In diabetes mellitus, hyperglycemia promotes the osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) to enhance medial vascular calcification, a common complication strongly associated with cardiovascular disease and mortality. The mechanisms involved are, however, still poorly understood. Therefore, the present study explored the potential role of serum- and glucocorticoid-inducible kinase 1 (SGK1) during vascular calcification promoted by hyperglycemic conditions. Exposure to high-glucose conditions up-regulated the SGK1 expression in primary human aortic VSMCs. High glucose increased osteogenic marker expression and activity and, thus, promoted the osteogenic transdifferentiation of VSMCs, effects significantly suppressed by additional treatment with the SGK1 inhibitor EMD638683. Moreover, high glucose augmented the mineralization of VSMCs in the presence of calcification medium, effects again significantly reduced by SGK1 inhibition. Similarly, SGK1 knockdown blunted the high glucose-induced osteogenic transdifferentiation of VSMCs. The osteoinductive signaling promoted by high glucose required SGK1-dependent NF-kB activation. In addition, advanced glycation end products (AGEs) increased the SGK1 expression in VSMCs, and SGK1 inhibition was able to interfere with AGEs-induced osteogenic signaling. In conclusion, SGK1 is up-regulated and mediates, at least partly, the osteogenic transdifferentiation and calcification of VSMCs during hyperglycemic conditions. Thus, SGK1 inhibition may reduce the development of vascular calcification promoted by hyperglycemia in diabetes.


Assuntos
Calcinose/genética , Diabetes Mellitus/genética , Hiperglicemia/genética , Proteínas Imediatamente Precoces/genética , Proteínas Serina-Treonina Quinases/genética , Aorta/crescimento & desenvolvimento , Aorta/metabolismo , Aorta/patologia , Benzamidas/farmacologia , Calcinose/metabolismo , Calcinose/patologia , Transdiferenciação Celular/genética , Diabetes Mellitus/patologia , Glucose/efeitos adversos , Produtos Finais de Glicação Avançada/genética , Humanos , Hidrazinas/farmacologia , Hiperglicemia/patologia , Proteínas Imediatamente Precoces/antagonistas & inibidores , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Osteogênese/genética , Cultura Primária de Células , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Transdução de Sinais/genética
9.
Oecologia ; 183(2): 519-530, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27832367

RESUMO

In anticipation of more severe summer droughts, forestry in temperate Europe is searching for drought-resistant ecotypes of native tree species that might maintain ecosystem services in the future. We investigated how spring precipitation and soil conditions interact with summer drought and affect the establishment of conifer seedlings from different climatic origin. Emergence, establishment and subsequent performance of seedlings originating from autochthonous, Central Alpine, continental Eastern European, and Mediterranean Pinus sylvestris and Picea abies populations were studied in the dry Alpine Rhine valley, Switzerland, at three sites with differing soil water holding capacities and in 3 years with contrasting weather conditions. In addition to this natural inter-annual variation, precipitation was manipulated within sites with throughfall reduction roofs. Seedling establishment and growth were principally affected by the spring weather in the year of emergence. In years with average to positive spring water balance, seedlings grown at the site with the highest water holding capacity had 2-5 times more aboveground biomass than seedlings grown at sites with less favourable soils. Effects of seed origin were marginal and only detectable at the drier sites: contrary to our expectations, seedlings from the Central Alpine Rhone valley, where the climatic spring water deficit is large, outperformed those from the Mediterranean. Consequently, plantation of non-native populations from dryer origin will mitigate the effects of increased summer drought at driest sites only, while the inter-annual variability of spring precipitation will continue to enable temperate conifers to regenerate on a wide range of forest soils independent of seed origin.


Assuntos
Secas , Solo , Traqueófitas , Estações do Ano , Sementes , Água
10.
Graefes Arch Clin Exp Ophthalmol ; 255(11): 2247-2253, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28815298

RESUMO

PURPOSE: A gaze shift from a target at distance to a target at near leads to pupillary constriction. The regulation of this pupillary near response is ill known. We investigated the impact of accommodation, convergence, and proximity on the pupillary diameter. METHODS: We recorded pupil size and vergence eye movements with the use of an infrared eye tracker. We determined the pupillary response in four conditions: (1) after a gaze shift from far to near without accommodation, (2) after a gaze shift from far to near with neither accommodation nor convergence, (3) after accommodation alone, and (4) after accommodation with convergence without a gaze shift to near. These responses were compared to the pupil response of a full near response and to a gaze shift from one far target to another. RESULTS: We found a reliable pupillary near response. The removal of both accommodation and convergence in gaze shift from far to near abolished the pupillary near response. Accommodation alone did not induce pupillary constriction, while convergence and accommodation together induced a pupil response similar to the full near response. CONCLUSIONS: The main trigger for the pupillary response seems to be convergence. Neither accommodation nor proximity alone induce a significant pupillary constriction. This suggests that the miosis of the near triad is closely coupled to the vergence system rather than being independently regulated.


Assuntos
Acomodação Ocular , Convergência Ocular/fisiologia , Pupila/fisiologia , Adulto , Feminino , Voluntários Saudáveis , Humanos , Masculino , Adulto Jovem
11.
Mycorrhiza ; 26(8): 895-907, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27460217

RESUMO

Although the Burgundy truffle (Tuber aestivum) is an ectomycorrhizal fungus of important economic value, its subterranean life cycle and population biology are still poorly understood. Here, we determine mating type and simple sequence repeat (SSR) maternal genotypes of mapped fruiting bodies to assess their genetic structure within two naturally colonized forest sites in southern Germany. Forty-one genotypes were identified from 112 fruiting bodies. According to their mating types, the maternal genotypes were aggregated only in one population. Genotypic diversity of individuals that mostly were small and occurred in 1 out of 2 years of sampling was high. Although these results suggested a ruderal colonization strategy, some genets spread several hundred meters. This result indicates that, besides sexual spore dispersal, vegetative growth or spreading by mycelial propagules contributes to dissemination. In one site, fewer individuals with a tendency to expand genets belonging to only one genetic group were observed. In the second site, numerous small individuals were found and were grouped into two clearly differentiated genetic groups that were spatially intermingled. Forest characteristics and disturbances are possible reasons for the observed genetic patterns. Our findings contribute to a better understanding of the biology of one of the most widespread and commercially important truffle species. This knowledge is critical for establishing and maintaining sustainable long-term truffle cultivations.


Assuntos
Ascomicetos/genética , Micorrizas/genética , DNA Fúngico/genética , Carpóforos , Genes Fúngicos Tipo Acasalamento/genética , Marcadores Genéticos , Variação Genética , Genótipo , Alemanha
12.
Oecologia ; 169(1): 269-79, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22081261

RESUMO

Increased summer drought will exacerbate the regeneration of many tree species at their lower latitudinal and altitudinal distribution limits. In vulnerable habitats, introduction of more drought-tolerant provenances or species is currently considered to accelerate tree species migration and facilitate forest persistence. Trade-offs between drought adaptation and growth plasticity might, however, limit the effectiveness of assisted migration, especially if introductions focus on provenances or species from different climatic regions. We tested in a common garden experiment the performance of Pinus sylvestris seedlings from the continental Central Alps under increased temperatures and extended spring and/or summer drought, and compared seedling emergence, survival and biomass allocation to that of P. sylvestris and closely related Pinus nigra from a Mediterranean seed source. Soil heating had only minor effects on seedling performance but high spring precipitation doubled the number of continental P. sylvestris seedlings present after the summer drought. At the same time, twice as many seedlings of the Mediterranean than the continental P. sylvestris provenance were present, which was due to both higher emergence and lower mortality under dry conditions. Both P. sylvestris provenances allocated similar amounts of biomass to roots when grown under low summer precipitation. Mediterranean seedlings, however, revealed lower phenotypic plasticity than continental seedlings under high precipitation, which might limit their competitive ability in continental Alpine forests in non-drought years. By contrast, high variability in the response of individual seedlings to summer drought indicates the potential of continental P. sylvestris provenances to adapt to changing environmental conditions.


Assuntos
Mudança Climática , Meio Ambiente , Fenótipo , Pinus sylvestris/fisiologia , Pinus/fisiologia , Biomassa , Secas , Variação Genética , Genótipo , Região do Mediterrâneo , Pinus/genética , Pinus/crescimento & desenvolvimento , Pinus sylvestris/genética , Pinus sylvestris/crescimento & desenvolvimento , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia
13.
Oecologia ; 167(1): 219-28, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21468664

RESUMO

Fires shape fundamental properties of many forest ecosystems and climate change will increase their relevance in regions where fires occur infrequently today. In ecosystems that are not adapted to fire, post-fire tree recruitment is often sparse, a fact that might be attributed to a transient lack of mycorrhizae. Ectomycorrhizal (EcM) fungi play an important role for recruitment by enhancing nutrient and water uptake of their hosts. The questions arise whether and for how long the EcM community is transformed by fire. We investigated the resistance and resilience of EcM fungal communities on a chronosequence of 12 Pinus sylvestris stands in Valais (Switzerland) and Val d'Aosta (Italy) affected by fire between 1990 and 2006. Soil samples from burnt and non-burnt forests were analyzed with respect to EcM fungi by means of a bioassay. The number of EcM species was significantly lower in samples from recently (2-5 years) burnt sites than non-burnt forest, and increased with time since fire reaching levels of adjacent forests after 15-18 years. Community composition changed after fire but did not converge to that of non-burnt sites over the 18 year period. Only Rhizopogon roseolus and Cenococcum geophilum were abundant in both burnt sites and adjacent forest. Our data indicate fire resistance of some EcM fungal species as well as rapid resilience in terms of species number, but not in species composition. As long as the function of different EcM species for seedling establishment is unknown, the consequences of long-term shifts in EcM community composition for tree recruitment remain unclear.


Assuntos
Ecossistema , Incêndios , Micorrizas/crescimento & desenvolvimento , Pinus sylvestris/microbiologia , Microbiologia do Solo , Itália , Suíça
14.
Environ Monit Assess ; 174(1-4): 47-63, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21049285

RESUMO

At Swiss long-term forest ecosystem research sites, ground vegetation was assessed during the period 1994-2003/2008 following two approaches: (1) visual assessment of the cover of species occurring in sixteen 1 m(2) quadrats, distributed over a 43 × 43 m area, and (2) phytosociological relevés in concentric circular plots of 30, 200, and 500 m(2). We first compared the two approaches with respect to diversity assessment. The number of species recorded in the 16 quadrats was in general higher than in the 30 m(2) plot and it represented 42% to 108% of the number of species recorded in the 500 m(2) plot. In a second step, we tested whether any temporal trends were apparent. In a few cases, a decrease or increase in Landolt's mean indicator values for light, nitrogen availability, soil pH, soil moisture, or temperature was found to be significant. However, these changes were usually restricted to one approach or one area. The only clear trend was detected in an unmanaged former coppice beech stand, for which all survey approaches indicated canopy closure. At another site, vegetation reacted to the local opening of the canopy following windthrow. In a third step, we compared the leaf area index (LAI), measured with an LAI-2000 instrument (Licor, Inc.) over each quadrat, with the indicator value of the vegetation for light (L). Within a site, there was no clear relationship between LAI and L values per quadrat. In contrast, across all sites, the relationship between LAI and L, averaged per site for all available years, was highly significant.


Assuntos
Monitoramento Ambiental , Árvores , Biodiversidade , Coleta de Dados , Suíça
15.
Protein Expr Purif ; 71(2): 160-7, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20153430

RESUMO

We present a novel efficient procedure for high level purification of human IGFBP-3. Insulin-like growth factor-binding proteins (IGFBPs) are key regulators of insulin-like growth factor mediated signal transduction and thereby can profoundly influence cellular phenotypes. Certain IGFBPs, including IGFBP-3, have also been described to possess additional IGF-independent activities, which rely, at least in part, on their nuclear localization. However, the mechanisms of IGF-independent biological activities of IGFBP-3 are not well understood. For the study of these functions, recombinant IGFBP-3 is used. However, it has traditionally been difficult to obtain recombinant protein in sufficient quality and quantity. Here we describe a new procedure for the purification of recombinant IGFBP-3 from cell culture supernatants involving a two-step affinity purification procedure. Using this new protocol, we obtained pure IGFBP-3 free of any visible contaminants. We also provide evidence that the protein purified in this way retains biological activity, to bind IGF and modulate IGF-dependent signal transduction. We also show that the purified protein produced by the new procedure is readily internalized by human fibroblasts, suggesting that this protein is also suitable to study intracellular trafficking of IGFBP-3.


Assuntos
Cromatografia de Afinidade , Fibroblastos/metabolismo , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/metabolismo , Somatomedinas/metabolismo , Humanos , Ligação Proteica , Proteínas Recombinantes/metabolismo , Transdução de Sinais
16.
Front Plant Sci ; 11: 539584, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33329621

RESUMO

Temperature manipulation experiments are an effective way for testing plant responses to future climate conditions, especially for predicting shifts in plant phenological events. While passive warming techniques are widely used to elevate temperature in low stature plant communities, active warming has been applied less frequently due to the associated resource requirements. In forest ecosystems, however, active warming is crucial to simulate projected air temperature rises of 3-5 K, especially at the warm (i.e., southern and low elevation) range edges of tree species. Moreover, the warming treatment should be applied to the complete height of the experimental plants, e.g., regenerating trees in the understory. Here, we combined open top chambers (OTCs) with active heat sources, an electric heater (OTC-EH) and warming cables (OTC-WC), and tested the effectiveness of these set-ups to maintain constant temperature differences compared to ambient temperature across 18 m2 plots. This chamber size is needed to grow tree saplings in mixture in forest gaps for 3 to 10 years. With passive warming only, an average temperature increase of approx. 0.4 K as compared to ambient conditions was achieved depending on time of the day and weather conditions. In the actively warmed chambers, average warming exceeded ambient temperatures by 2.5 to 2.8 K and was less variable over time. However, active warming also reduced air humidity by about 15%. These results underline the need to complement passive warming with active warming in order to achieve constant temperature differences appropriate for climate change simulations under all weather conditions in large OTCs. Since we observed considerable horizontal and vertical temperature variation within OTCs with temperature differences of up to 16.9 K, it is essential to measure and report within-plot temperature distribution as well as temporal temperature variation. If temperature distributions within large OTCs are well characterized, they may be incorporated in the experimental design helping to identify non-linear or threshold responses to warming.

17.
Plants (Basel) ; 9(5)2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32413963

RESUMO

(1) Understanding tree seedling responses to water, nutrient, and light availability is crucial to precisely predict potential shifts in composition and structure of forest communities under future climatic conditions. (2) We exposed seedlings of widespread Central European tree species with contrasting leaf habit, deciduous broadleaves (DB) and evergreen conifers (EC), to factorial combinations of manipulated precipitation (100% and 50% of ambient), shade (40% and 60% of full sunlight), and nutrient availability (low and high NPK), and measured specific leaf area, C/N ratio, soluble sugars, starch and non-structural carbohydrate concentration, and δ13C of the leaves. (3) We found contrasting effects of water and nutrient availability on foliar traits of the two species groups: EC exhibited higher tolerance to low resource availability but also less plasticity in foliar traits, which is congruent with a "slow" resource strategy. In contrast, foliage of DB reacted particularly to altered nutrient availability, corresponding to a "fast" resource strategy with high foliar plasticity and rapid adjustments to resource fluctuations, commonly adopted by species with high growth rates. (4) We conclude that DB will respond to environmental change with foliar acclimation, while EC will either tolerate, to some extent, or shift their distribution range in response to environmental change.

18.
Cancer Res ; 66(6): 3024-33, 2006 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-16540651

RESUMO

Insulin-like growth factor binding protein-3 (IGFBP-3), the product of a tumor suppressor target gene, can modulate cell proliferation and apoptosis by IGF-I-dependent and IGF-I-independent mechanisms. IGFBP-3 controls the bioavailability of IGFs in the extracellular environment and is known to be subject to degradation by various extracellular proteases. Although nuclear localization and functions of IGFBP-3 have been described in the past, we show as the novel features of this study that the abundance of nuclear IGFBP-3 is directly regulated by ubiquitin/proteasome-dependent proteolysis. We show that IGFBP-3 degradation depends on an active ubiquitin-E1 ligase, specific 26S proteasome inhibitors can efficiently stabilize nuclear IGFBP-3, and the metabolic half-life of nuclear IGFBP-3 is strongly reduced relative to cytoplasmic IGFBP-3. Nuclear IGFBP-3 is highly polyubiquitinated at multiple lysine residues in its conserved COOH-terminal domain and stabilized through mutation of two COOH-terminal lysine residues. Moreover, we show that IGFBP-3, if ectopically expressed in the nucleus, can induce apoptotic cell death. These results suggest that ubiquitin/proteasome-mediated proteolysis of IGFBP-3 may contribute to down-regulation of apoptosis.


Assuntos
Apoptose/fisiologia , Neoplasias Ósseas/metabolismo , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Osteossarcoma/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Neoplasias Ósseas/enzimologia , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Núcleo Celular/enzimologia , Núcleo Celular/metabolismo , Citosol/enzimologia , Citosol/metabolismo , Humanos , Osteossarcoma/enzimologia , Osteossarcoma/patologia , Enzimas Ativadoras de Ubiquitina/metabolismo
19.
Carcinogenesis ; 28(12): 2511-20, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17827406

RESUMO

The E7 protein encoded by the oncogenic human papillomavirus type 16 has been shown to bind and inactivate insulin-like growth factor-binding protein-3 (IGFBP-3), the pro-apoptotic product of a tumour suppressor gene; however, the molecular mechanism underlying E7-induced inactivation of IGFBP-3 remained uncertain. In this study, we map the IGFBP-3-binding domain for E7 to the nuclear localization signal in the conserved C-terminal domain of IGFBP-3. Moreover, we demonstrate that both proteins interact in the nucleus and that E7 induces polyubiquitination and proteasome-dependent proteolysis of nuclear IGFBP-3 in cervical cancer cells. This leads to a dramatic shortening of the half-life of nuclear IGFBP-3, whereas the stability of an E7-non-binding IGFBP-3 mutant is not affected by E7. Finally, we show that E7-mediated destruction of nuclear IGFBP-3 correlates with the inhibition of IGFBP-3-induced apoptotic cell death. These data are consistent with E7-induced ubiquitin/proteasome-dependent inactivation of nuclear IGFBP-3.


Assuntos
Apoptose/fisiologia , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/fisiologia , Proteínas Oncogênicas Virais/fisiologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Feminino , Humanos , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Mutação , Proteínas Oncogênicas Virais/genética , Proteínas E7 de Papillomavirus , Ligação Proteica , Estrutura Terciária de Proteína , Neoplasias do Colo do Útero
20.
J Virol Methods ; 134(1-2): 30-5, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16384614

RESUMO

E7 proteins are major oncoproteins of human papillomaviruses (HPVs) which play a key role in virus-associated cervical carcinogenesis. The E7 oncoprotein of HPV-16 has been shown to interact with a variety of cellular target proteins and these interactions are considered essential for the transforming properties of this oncoprotein. Several additional HPV types associated etiologically to cervical cancer have been described, the second most common being HPV-18. Less is known about the biochemical functions and interactions of HPV-18 E7. As a first step to determine biochemical properties common to the E7 proteins of the high-risk HPV types 16 and 18 these E7 proteins were expressed in bacteria and purified to homogeneity. Purified E7 proteins were used to investigate the in vitro interaction with the pocket protein p107 and insulin-like growth factor-binding protein-3 (IGFBP-3) that are known to interact with the amino-terminal and the carboxyl-terminal part of IGFBP-3, respectively. Both purified E7 proteins interacted strongly with p107 and, as demonstrated here for the first time, HPV-18 E7 was capable of binding to IGFBP-3, albeit to a lesser extent than HPV-16 E7. These findings suggest that the purified recombinant E7 proteins retain, at least in part, their biochemical activities.


Assuntos
Proteínas de Ligação a DNA/isolamento & purificação , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/metabolismo , Proteínas Oncogênicas Virais/isolamento & purificação , Engenharia de Proteínas , Proteína p107 Retinoblastoma-Like/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Escherichia coli/metabolismo , Proteínas Oncogênicas Virais/genética , Proteínas Oncogênicas Virais/metabolismo , Proteínas E7 de Papillomavirus , Ligação Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/metabolismo
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