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81.
Luis Giménez-Benavides Raúl García-Camacho José María Iriondo Adrián Escudero 《Evolutionary ecology》2011,25(4):777-794
Under climate warming, plants will undergo novel selective pressures to adjust reproductive timing. Adjustment between reproductive
phenology and environment is expected to be higher in arctic and alpine habitats because the growing season is considerably
short. As early- and late-flowering species reproduce under very different environmental conditions, selective pressures on
flowering phenology and potential effects of climate change are likely to differ between them. However, there is no agreement
on the magnitude of the benefits and costs of early- vs. late-flowering species under a global warming scenario. In spite
of its relevance, phenotypic selection on flowering phenology has rarely been explored in alpine plants and never in Mediterranean
high mountain species, where selective pressures are very different due to the summer drought imposed over the short growth
season. We hypothesized that late-flowering plants in Mediterranean mountains should present stronger selective pressures
towards early onset of reproduction than early-flowering species, because less water is available in the soil as growing season
progresses. We performed selection analyses on flowering onset and duration in two high mountain species of contrasting phenology.
Since phenotypic selection can be highly context-dependent, we studied several populations of each species for 2 years, covering
their local altitudinal ranges and their different microhabitats. Surrogates of biotic selective agents, like fruitset for
pollinators and flower and fruit loss for flower and seed predators, were included in the analysis. Differences between the
early- and the late-flowering species were less than expected. A consistent negative correlational selection of flowering
onset and duration was found affecting plant fitness, i.e., plants that bloomed earlier flowered for longer periods improving
plant fitness. Nevertheless, the late-flowering species may experience higher risks under climate warming because in extremely
warm and dry years the earlier season does not bring about a longer flowering duration due to summer drought. 相似文献
82.
Gloria Alvarez-Sola Iker Uriarte Maria U. Latasa Maddalen Jimenez Marina Barcena-Varela Eva Santamaría Raquel Urtasun Carlos Rodriguez-Ortigosa Jesús Prieto Pedro Berraondo Maite G. Fernandez-Barrena Carmen Berasain Matías A. Avila 《生物化学与生物物理学报:疾病的分子基础》2018,1864(4):1326-1334
The liver has an extraordinary regenerative capacity rapidly triggered upon injury or resection. This response is intrinsically adjusted in its initiation and termination, a property termed the “hepatostat”. Several molecules have been involved in liver regeneration, and among them bile acids may play a central role. Intrahepatic levels of bile acids rapidly increase after resection. Through the activation of farnesoid X receptor (FXR), bile acids regulate their hepatic metabolism and also promote hepatocellular proliferation. FXR is also expressed in enterocytes, where bile acids stimulate the expression of fibroblast growth factor 15/19 (FGF15/19), which is released to the portal blood. Through the activation of FGFR4 on hepatocytes FGF15/19 regulates bile acids synthesis and finely tunes liver regeneration as part of the “hepatostat”. Here we review the experimental evidences supporting the relevance of the FXR-FGF15/19-FGFR4 axis in liver regeneration and discuss potential therapeutic applications of FGF15/19 in the prevention of liver failure. This article is part of a Special Issue entitled: Cholangiocytes in Health and Disease edited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen. 相似文献
83.
Rita Rocha Celso M. Teixeira-Duarte João M.P. Jorge João Henrique Morais-Cabral 《Journal of structural biology》2019,205(3):34-43
RCK (regulating conductance of K+) domains are common regulatory domains that control the activity of eukaryotic and prokaryotic K+ channels and transporters. In bacteria these domains play roles in osmoregulation, regulation of turgor and membrane potential and in pH homeostasis. Whole-genome sequencing unveiled RCK gene redundancy, however the biological role of this redundancy is not well understood. In Bacillus subtilis, there are two closely related RCK domain proteins (KtrA and KtrC) that regulate the activity of the Ktr cation channels. KtrA has been well characterized but little is known about KtrC. We have characterized the structural and biochemical proprieties of KtrC and conclude that KtrC binds ATP and ADP, just like KtrA. However, in solution KtrC exist in a dynamic equilibrium between octamers and non-octameric species that is dependent on the bound ligand, with ATP destabilizing the octameric ring relative to ADP. Accordingly, KtrC-ADP crystal structures reveal closed octameric rings similar to those in KtrA, while KtrC-ATP adopts an open assembly with RCK domains forming a super-helix. In addition, both KtrC-ATP and -ADP octamers are stabilized by the signaling molecule cyclic-di-AMP, which binds to KtrC with high affinity. In contrast, c-di-AMP binds with 100-fold lower affinity to KtrA. Despite these differences we show with an E. coli complementation assay that KtrC and KtrA are interchangeable and able to form functional transporters with both KtrB and KtrD. The distinctive properties of KtrC, in particular ligand-dependent assembly/disassembly, suggest that this protein has a specific physiological role that is distinct from KtrA. 相似文献
84.
Vanessa B. Fortes Júlio César Bicca-Marques 《International journal of primatology》2008,29(3):717-722
We located 4 brown howlers (1 adult male, 2 adult females, and 1 juvenile male) showing abnormally lighter pelage in 3 social
groups comprising 5, 6, and 9 individuals in a 20 ha-forest fragment in the State of Rio Grande do Sul, Brazil. Two additional
groups composed only of normally colored individuals also live in the fragment, which is isolated from nearby fragments by
267–1009 m. They were the only brown howlers with abnormal pelage color out of a total of 386 individuals belonging to 67
groups in 21 fragments in the 5876-ha study area. The isolation of the forest fragment, its high howler density (2.2 individuals⁄ha),
and large group size (8.8 ± 2.4 individuals) may decrease the likelihood of successful immigration into the population, leading
to an increased probability of inbreeding that may facilitate the expression of rare alleles. 相似文献
85.
Shanna Bitencourt Fernanda Mesquita Bruno Basso Júlia Schmid Gabriela Ferreira Lucas Rizzo Moises Bauer Ramon Bartrons Francesc Ventura Jose Luis Rosa Inge Mannaerts Leo Adrianus van Grunsven Jarbas Oliveira 《Cell biochemistry and biophysics》2014,68(2):387-396
Capsaicin, the active component of chili pepper, has been reported to have antiproliferative and anti-inflammatory effects on a variety of cell lines. In the current study, we aimed to investigate the effects of capsaicin during HSC activation and maintenance. Activated and freshly isolated HSCs were treated with capsaicin. Proliferation was measured by incorporation of EdU. Cell cycle arrest and apoptosis were investigated using flow cytometry. The migratory response to chemotactic stimuli was evaluated by a modified Boyden chamber assay. Activation markers and inflammatory cytokines were determined by qPCR, immunocytochemistry, and flow cytometry. Our results show that capsaicin reduces HSC proliferation, migration, and expression of profibrogenic markers of activated and primary mouse HSCs. In conclusion, the present study shows that capsaicin modulates proliferation, migration, and activation of HSC in vitro. 相似文献
86.
Asmita Banerjee Sylvia Nürnberger Simone Hennerbichler Sabrina Riedl Christina M. A. P. Schuh Ara Hacobian Andreas Teuschl Johann Eibl Heinz Redl Susanne Wolbank 《Cell and tissue banking》2014,15(2):227-239
Human amniotic membrane (hAM) is a tissue containing cells with proven stem cell properties. In its decellularized form it has been successfully applied as nerve conduit biomaterial to improve peripheral nerve regeneration in injury models. We hypothesize that viable hAM without prior cell isolation can be differentiated towards the Schwann cell lineage to generate a possible alternative to commonly applied tissue engineering materials for nerve regeneration. For in vitro Schwann cell differentiation, biopsies of hAM of 8 mm diameter were incubated with a sequential order of neuronal induction and growth factors for 21 days and characterized for cellular viability and the typical glial markers glial fibrillary acidic protein (GFAP), S100β, p75 and neurotrophic tyrosine kinase receptor (NTRK) using immunohistology. The secretion of the neurotrophic factors brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor (GDNF) was quantified by ELISA. The hAM maintained high viability, especially under differentiation conditions (90.2 % ± 41.6 day 14; 80.0 % ± 44.5 day 21 compared to day 0). Both, BDNF and GDNF secretion was up-regulated upon differentiation. The fresh membrane stained positive for GFAP and p75 and NTRK, which was strongly increased after culture in differentiation conditions. Especially the epithelial layer within the membrane exhibited a change in morphology upon differentiation forming a multi-layered epithelium with intense accumulations of the marker proteins. However, S100β was expressed at equal levels and equal distribution in fresh and cultured hAM conditions. Viable hAM may be a promising alternative to present formulations used for peripheral nerve regeneration. 相似文献
87.
Lipase immobilisation on to polymeric membranes 总被引:2,自引:0,他引:2
M. G. Carneiro-da-Cunha J. M. S. Rocha F. A. P. Garcia M. H. Gil 《Biotechnology Techniques》1999,13(6):403-409
Lipase (EC 3.1.1.3) from Candida rugosa was covalently immobilised on to cellulose, cellulose derivatives (cellulose acetate and cellulose phthalate) and cellulose composite membranes using activating agents such as sodium periodate or carbodiimide. Other non-cellulosic polymeric membranes (nylon, polyurethane, chitosan and hydroxyethyl methacrylate-co-methyl methacrylate) were also prepared and used for lipase immobilisation. The results obtained showed that the expressed activities are of the same order of magnitude for similar enzyme loadings when compared with those obtained from literature. 相似文献
88.
89.
Tao Ke Filipe Marques Gonçalves Cinara Ludvig Gonçalves Alessandra Antunes dos Santos João B.T. Rocha Marcelo Farina Anatoly Skalny Aristidis Tsatsakis Aaron B. Bowman Michael Aschner 《生物化学与生物物理学报:疾病的分子基础》2019,1865(8):2068-2081
Mercury (Hg) exposure remains a major public health concern due to its widespread distribution in the environment. Organic mercurials, such as MeHg, have been extensively investigated especially because of their congenital effects. In this context, studies on the molecular mechanism of MeHg-induced neurotoxicity are pivotal to the understanding of its toxic effects and the development of preventive measures. Post-translational modifications (PTMs) of proteins, such as phosphorylation, ubiquitination, and acetylation are essential for the proper function of proteins and play important roles in the regulation of cellular homeostasis. The rapid and transient nature of many PTMs allows efficient signal transduction in response to stress. This review summarizes the current knowledge of PTMs in MeHg-induced neurotoxicity, including the most commonly PTMs, as well as PTMs induced by oxidative stress and PTMs of antioxidant proteins. Though PTMs represent an important molecular mechanism for maintaining cellular homeostasis and are involved in the neurotoxic effects of MeHg, we are far from understanding the complete picture on their role, and further research is warranted to increase our knowledge of PTMs in MeHg-induced neurotoxicity. 相似文献
90.
Bombesin induces c-fos and c-myc expression in quiescent Swiss 3T3 cells. Comparative study with other mitogens 总被引:6,自引:0,他引:6
R Bravo H Macdonald-Bravo R Müller D Húbsch J M Almendral 《Experimental cell research》1987,170(1):103-115
We have studied the effect of the potent mitogen bombesin on the expression of c-fos and c-myc genes in quiescent mouse fibroblasts. We have demonstrated that bombesin rapidly induces a transient expression of c-fos mRNA followed by a more protracted elevation in c-myc mRNA levels. The intensity of the induction of expression of both proto-oncogenes depended on the dose of bombesin used. Prolonged treatment of the cells with TPA, which causes a selective decrease in protein kinase C activity, partially inhibited the induction of c-fos and c-myc gene expression by bombesin, similar to what has been observed with PDGF. However, a dramatic inhibition of the mitogenic response to bombesin--but not to PDGF--was found in TPA-treated cells. In contrast, TPA-treated cells showed an increased response to EGF with regard to proto-oncogene expression. The role of protein kinase C and Ca2+-dependent pathways in proto-oncogene induction by bombesin is discussed. 相似文献