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991.
G. Tomlinson N. Buchmann R. Siegwolf P. Weber A. Thimonier E. Graf Pannatier M. Schmitt M. Schaub P. Waldner 《Trees - Structure and Function》2016,30(3):627-638
Key message
For long-term environmental investigations, tree-ring δ 15 N values are inappropriate proxies for foliar δ 15 N for both Fagus sylvatica and Picea abies under moderate N loads.Abstract
Currently it is unclear whether stable nitrogen isotope signals of tree-rings are related to those in foliage, and whether they can be used to infer tree responses to environmental changes. We studied foliar and tree-ring nitrogen (δ15N) and carbon (δ13C) isotope ratios in European beech (Fagus sylvatica L.) and Norway spruce (Picea abies L.) from six long-term forest monitoring sites in Switzerland together with data on N deposition and soil N availability, as well as a drought response index over the last two decades. For both species, tree-ring δ15N and δ13C values were less negative compared to foliar δ15N and δ13C values, most likely due to recycling and reallocation of N within the tree and fractionation processes associated with the transport of sucrose and the formation of tree-rings, respectively. Temporal trends recorded in foliar δ15N were not reflected in tree-ring δ15N, with much higher variations in tree-rings compared to foliage. Soil N availability and N deposition were partially able to explain changes in foliar δ13C, while there were no significant correlations between environmental variables and either tree-ring or foliar δ15N. Our results suggest an uncoupling between the N isotopic composition of tree-rings and foliage. Consequently, tree-ring δ15N values are inappropriate proxies of foliar δ15N values under low-to-moderate N deposition loads. Furthermore, at such low levels of deposition, tree-ring δ15N values are not recommended as archives of tree responses to soil C/N or bulk N deposition.992.
993.
Antonia Yarur Esteban Soto Gabriel León Andrea Miyasaka Almeida 《Sexual plant reproduction》2016,29(4):311-322
994.
995.
Cristiane Lenz Dalla Corte Angélica Ramos Clarissa Marques Moreira dos Santos Valderi Luiz Dressler João Batista Teixeira da Rocha 《Biometals》2016,29(3):543-550
Organoseleno-compounds have been investigated for its beneficial effects against methylmercury toxicity. In this way, diphenyl diselenide (PhSe)2 was demonstrated to decrease Hg accumulation in mice, protect against MeHg-induced mitochondrial dysfunction, and protect against the overall toxicity of this metal. In the present study we aimed to investigate if co-treatment with (PhSe)2 and MeHg could decrease accumulation of Hg in liver slices of rats. Rat liver slices were co-treated with (PhSe)2 (0.5; 5 µM) and/or MeHg (25 µM) for 30 min at 37 °C and Se and Hg levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) in the slices homogenate, P1 fraction, mitochondria and incubation medium. Co-treatment with (PhSe)2 and MeHg did not significantly alter Se levels in any of the samples when compared with compounds alone. In addition, co-treatment with (PhSe)2 and MeHg did not decrease Hg levels in any of the samples tested, although, co-incubation significantly increased Hg levels in homogenate. We suggest here that (PhSe)2 could exert its previously demonstrated protective effects not by reducing MeHg levels, but forming a complex with MeHg avoiding it to bind to critical molecules in cell. 相似文献
996.
Leadmium Green is a commercially available, small molecule, fluorescent probe advertised as a detector of free intracellular cadmium (Cd2+) and lead (Pb2+). Leadmium Green has been used in various paradigms, such as tracking Cd2+ sequestration in plant cells, heavy metal export in protozoa, and Pb2+ absorption by vascular endothelial cells. However very little information is available regarding its affinity and selectivity for Cd2+, Pb2+, and other metals. We evaluated the in vitro selectivity of Leadmium Green using spectrofluorimetry. Consistent with manufacturer’s claims, Leadmium Green was sensitive to Cd2+ (KD ~600 nM) and also Pb2+ (KD ~9.0 nM) in a concentration-dependent manner, and furthermore proved insensitive to Ca2+, Co2+, Mn2+ and Ni2+. Leadmium Green also responded to Zn2+ with a KD of ~82 nM. Using fluorescence microscopy, we evaluated Leadmium Green in live mouse hippocampal HT22 cells. We demonstrated that Leadmium Green detected ionophore-mediated acute elevations of Cd2+ or Zn2+ in a concentration-dependent manner. However, the maximum fluorescence produced by ionophore-delivered Zn2+ was much less than that produced by Cd2+. When tested in a model of oxidant-induced liberation of endogenous Zn2+, Leadmium Green responded weakly. We conclude that Leadmium Green is an effective probe for monitoring intracellular Cd2+, particularly in models where Cd2+ accumulates rapidly, and when concomitant fluctuations of intracellular Zn2+ are minimal. 相似文献
997.
Natacha E. Piloni Juan C. Perazzo Virginia Fernandez Luis A. Videla Susana Puntarulo 《Biometals》2016,29(1):119-130
This work was aimed to test the hypothesis that sub-chronic administration of iron-dextran (Fe-dextran) (six doses of 50 mg Fe-dextran/kg) to rats triggers a transient oxidative stress in brain and mechanisms of cellular antioxidant defence. After 2 h of administration of the 6th dose, a significant increase of total Fe, the labile Fe pool (LIP), the lipid radical (LR?)/α-tocopherol (α-T) content ratio were observed, as compared to values in control brain homogenates. The ascorbyl radical (A?)/ascorbate (AH?) content ratio and the oxidation rate of 2′,7′-dichlorodihidrofluorescein (DCFH-DA) were significantly higher in Fe-dextran treated rats, as compared to values in brain from control rats after 4 h treatment. An increase in both catalase (CAT) and superoxide dismutase (SOD) activity was observed at 8 and 1–2 h, respectively. No significant changes were detected in the nuclear factor-κB (NF-κB) levels in nuclear extracts from rat brains after 1–8 h of Fe-dextran administration. After 2 h of Fe administration Fe concentration in cortex, striatum and hippocampus was significantly increased as compared to the same areas from control animals. Both, CAT and SOD activities were significantly increased in cortex after Fe administration over control values, without changes in striatum and hippocampus. Taken as a whole, sub-chronic Fe administration enhances the steady state concentration of Fe in the brain LIP that favors the settlement of an initial oxidative stress condition, both at hydrophilic and lipophilic compartments, resulting in cellular protection evidenced by antioxidant enzyme upregulation. 相似文献
998.
Males in many non-monogamous species have larger ranges than females do, a sex difference that has been well documented for decades and seems to be an aspect of male mating competition. Until recently, parallel data for humans have been mostly anecdotal and qualitative, but this is now changing as human behavioral ecologists turn their attention to matters of individual mobility. Sex differences in spatial cognition were among the first accepted psychological sex differences and, like differences in ranging behavior, are documented for a growing set of species. This special issue is dedicated to exploring the possible adaptive links between these cognitive and ranging traits. Multiple hypotheses, at various levels of analysis, are considered. At the functional (ultimate) level, a mating-competition hypothesis suggests that range expansion may augment mating opportunities, and a fertility-and-parental-care hypothesis suggests that range contraction may facilitate offspring provisioning. At a more mechanistic (proximate) level, differences in cue availability may support or inhibit particular sex-specific navigation strategies, and spatial anxiety may usefully inhibit travel that would not justify its costs. Studies in four different cultures—Twe, Tsimane, Yucatec Maya, and Faroese—as well as an experimental study using virtual reality tools are the venue for testing these hypotheses. Our hope is to stimulate more research on the evolutionary and developmental processes responsible for this suite of linked behavioral and cognitive traits. 相似文献
999.
Montserrat Soler 《Human nature (Hawthorne, N.Y.)》2016,27(4):372-394
Despite secular trends in some countries, prestige-based authority in the form of religious leadership remains hugely influential in the everyday lives of millions of people around the world. Here, the costs and benefits of religious leadership are explored in an urban setting in northeastern Brazil. An economic game, within-group cooperation questionnaires, and social network analyses were carried out among adherents of an Afro-Brazilian religion. Results reveal that leaders display high levels of religious commitment and disproportionally provide cooperative services to group members. On the other hand, initiates cooperate less than leaders but do not differ in levels of received cooperation or social cohesion measures. This may indicate some level of exploitation or free-riding. Demographic and group variables also appear to play an important role in the degree of social cohesion a group achieves. These findings are discussed in the context of non-Western urban settings where religious leadership may represent both an alternative to social advancement and a crucial source of material aid, social support, and a strong sense of community. 相似文献
1000.
Angelika Noga Edyta Skrzypek Marzena Warchoł Ilona Czyczyło-Mysza Kinga Dziurka Izabela Marcińska Katarzyna Juzoń Tomasz Warzecha Agnieszka Sutkowska Zygmunt Nita Krystyna Werwińska 《In vitro cellular & developmental biology. Plant》2016,52(6):590-597
Obtaining oat DH lines is only effective via wide crossing with maize. Seven hundred haploid embryos from 21 single F1 progeny obtained from wide crosses with maize were isolated, divided into four groups according to their size (<0.5 mm, 0.5–0.9 mm, 1.0–1.4 mm, and ≥1.5 mm), and transferred into 190–2 regeneration medium with different growth regulators: 0.5 mg L?1 kinetin (KIN) and 0.5 mg L?1 1-naphthaleneacetic acid (NAA); 1 mg L?1 zeatin (ZEA) and 0.5 mg L?1 NAA; or 1 mg L?1 dicamba (DIC), 1 mg L?1 picloram (PIC), and 0.5 mg L?1 kinetin (KIN). Among all isolated embryos, approximately 46.1% were between 1.0–1.4 mm, while the smallest group of embryos (7.1%) were those <0.5 mm. The ability of haploid embryos to germinate varied depending on oat genotypes and the size of embryos. Haploid embryos <0.5 mm were globular and did not germinate, whereas embryos ≥1.5 mm had clearly visible coleoptiles, radicles, and scutella, and were able to germinate. Germination of oat haploid embryos varied depending on growth regulators in the regeneration medium. Most haploid embryos germinated on medium with 0.5 mg L?1 NAA and 0.5 mg L?1 KIN, while the fewest germinated on medium with 1 mg L?1 DIC, 1 mg L?1 PIC, and 0.5 mg L?1 KIN. One hundred thirty germinated haploid embryos converted into haploid plants. Fifty oat DH lines were obtained after colchicine treatment. 相似文献