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971.
Miguel A. Piñeros Geraldo M. A. Cançado Lyza G. Maron Sangbom M. Lyi Marcelo Menossi Leon V. Kochian 《The Plant journal : for cell and molecular biology》2008,53(2):352-367
The phytotoxic effects of aluminum (Al) on root systems of crop plants constitute a major agricultural problem in many areas of the world. Root exudation of Al-chelating molecules such as low-molecular-weight organic acids has been shown to be an important mechanism of plant Al tolerance/resistance. Differences observed in the physiology and electrophysiology of root function for two maize genotypes with contrasting Al tolerance revealed an association between rates of Al-activated root organic acid release and Al tolerance. Using these genotypes, we cloned ZmALMT1 , a maize gene homologous to the wheat ALMT1 and Arabidopsis AtALMT1 genes that have recently been described as encoding functional, Al-activated transporters that play a role in tolerance by mediating Al-activated organic acid exudation in roots. The ZmALMT1 cDNA encodes a 451 amino acid protein containing six transmembrane helices. Transient expression of a ZmALMT1 ::GFP chimera confirmed that the protein is targeted to the plant cell plasma membrane. We addressed whether ZmALMT1 might underlie the Al-resistance response (i.e. Al-activated citrate exudation) observed in the roots of the Al-tolerant genotype. The physiological, gene expression and functional data from this study confirm that ZmALMT1 is a plasma membrane transporter that is capable of mediating elective anion efflux and influx. However, gene expression data as well as biophysical transport characteristics obtained from Xenopus oocytes expressing ZmALMT1 indicate that this transporter is implicated in the selective transport of anions involved in mineral nutrition and ion homeostasis processes, rather than mediating a specific Al-activated citrate exudation response at the rhizosphere of maize roots. 相似文献
972.
Rogério Loesch Zacariotti Kathleen Fernandes Grego Wilson Fernandes Sávio Stefanini Sant'Anna Marcelo Alcindo de Barros Vaz Guimarães 《Zoo biology》2007,26(2):155-160
Two hundred‐ninety species of reptiles are estimated to need urgent action for conservation, with at least 113 threatened species worldwide. The International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species includes 80 species of snakes, with six native Brazilian species, a number likely to be an underestimation. Some authors believe that assisted reproduction would be an important tool to improve reproduction in captivity of some reptiles. An efficient technique for semen collection and evaluation is an important step in development of protocols for cryopreservation of semen or artificial insemination in snakes, contributing to the conservation of endangered species. Although these techniques are important, some basic semen parameters are described for four of the ~2,900 snake species in the world. The Brazilian rattlesnake (Crotalus durissus terrificus) was chosen as a model for semen collection in snakes because it is found quite often in Sao Paulo State. Semen was collected once from each animal by the same investigator during the mating season of this species in Brazil. After antiseptic cleansing of the skin around the cloaca, the snakes were injected subcutaneously with a dose of 15 mg/kg of 1% solution of lidocaine around the cloaca. Semen was collected with ventral massages after cloacal relaxation and directly from genital papilla inside the cloaca. A total of 28 ejaculates from 39 animals were obtained, representing collection efficiency of 71.80%. Semen volume and concentration in Brazilian rattlesnakes ranged from 3–70 µl and from 0.94–2.23 × 109 spermatozoa/ml, respectively. Zoo Biol 0:1–6, 2007. © 2007 Wiley‐Liss, Inc. 相似文献
973.
974.
The aim of this work was to analyse those characteristics of the Atlantic coast that are associated with distribution, abundance
and breeding activity of Otaria flavescens at three ecological scales. We followed a research strategy that consists in looking at the variables that are associated
with the pattern of distribution at regional and landscape scales, instead of following local population in time. We used
bibliographic data of censuses carried out between 1946 and 1997 and a Geographic Information System (GIS) to integrate information
proceeding from censuses and different environmental variables. At a regional scale, we found that the distribution of breeding
colonies did not vary in the period of time analysed and was associated with the pattern of occupation of the coast and the
tide width. There was a significant decrease in abundance between 1946 and 1997. In ‘north-central Patagonia’, the segment of coast with the highest number of sea lions in Argentina, distribution of colonies was associated with islands
availability and negatively correlated with places were anthropogenic disturbance was high. At a local scale, breeding colonies
were positive associated with slight slope coasts and negatively associated to rocky beaches. We identify those characteristics
of the coast associated with distribution of breeding colonies of O. flavescens, which operate at different ecological and temporal scales.
Handling editor: K. Martens 相似文献
975.
Ana Luisa Albernaz Robert L. Pressey Luiz R.F. Costa Marcelo P. Moreira José Ferreira Ramos Paulo A. Assunção Carlos H. Franciscon 《Journal of Biogeography》2012,39(5):869-883
Aim The aim of this study was to use compositional changes in tree species along the Amazon River floodplain in Brazil to identify and characterize biogeographic regions that would serve as broad surrogates for conservation planning. Location The main course of the Amazon River in Brazil, covering a river distance of approximately 2800 km. Methods Two sampling methods were employed at specific sites: standardized transects and/or individual‐based samples. Seventy‐three samples were collected from 26 sites at approximately 100‐km intervals along the floodplain. Biogeographic regions were identified by non‐metric multidimensional scaling (NMDS) ordination and by a hierarchical cluster analysis. The relative influence of environmental components (flood depths, annual rainfall, and length of the dry season) on tree species composition and one spatial component (longitude) were analysed by multiple regressions against a one‐dimensional NMDS ordination axis. Results Based on tree species composition, three main biogeographic regions were identified: a western region between Tabatinga and the Negro River confluence; a central region from the Negro River confluence to the Xingu confluence; and an estuarine region from the Xingu confluence to Santana. The regions identified were consistent using different data sets and analytical techniques. Mixed environmental and spatial effects explained most of the variation, but the spatial effect alone had a greater influence on species composition than environmental effects alone. Main conclusions The regions delimited in the analyses differed from those based on geomorphology or World Wildlife Fund (WWF) ecoregions. These results reinforce the need for surrogates to be tested against biological data before they are used to shape approaches to conservation planning. Although a protected area coverage of 25% gives the impression of extensive conservation management on the floodplain, less than 1% of the Amazon’s floodplain in Brazil is strictly protected. The significant compositional differences between regions and the strong spatial variation along the Amazon indicate that strict protection areas should be distributed much more evenly within and between regions. 相似文献
976.
977.
Marcelo Gleiser 《Origins of life and evolution of the biosphere》2007,37(3):235-251
The role of asymmetry on the evolution of prebiotic homochirality is investigated in the context of autocatalytic polymerization
reaction networks. A model featuring enantiometric cross-inhibition and chiral bias is used to study the diffusion equations
controlling the spatiotemporal development of left and right-handed domains. Bounds on the chiral bias are obtained based
on present-day constraints on the emergence of life on early Earth. The viability of biasing mechanisms such as weak neutral
currents and circularly polarized UV light is discussed. The results can be applied to any hypothetical planetary platform. 相似文献
978.
Marcelo Henrique Soller Ramada Roberto do Nascimento Silva 《Journal of microbiological methods》2010,81(1):6-10
β-1,3-glucanase is an important cell wall-degrading enzyme involved in mycoparasitism by Trichoderma spp. during antagonism against phytopathogenic fungi. A simple microplate-based method to assay β-1,3-glucanase activity is described here as an alternative to an expensive tube-assay method. The reaction volume of the micro-assay was reduced to 130 µl from the 1150 µl used in the standard β-1,3-glucanase macro-assay. Statistical analyses showed significant difference in sensitivity between the micro- and the macro-assay. The micro-method was optimized using the Response Surface Quadratic Model. The sensitivity of the optimized micro-method was shown to be four-fold greater than the macro-assay and two-fold higher than the micro-assay. The optimized micro-assay was significantly more sensitive in all of the twenty examined isolates during Trichoderma spp. β-1,3-glucanase screening. We conclude that this modified and optimized method is more convenient, faster, cheaper and more reproducible than the traditional tube-assay. 相似文献
979.
Marcelo Coba Emer M Garry Roberta Rosie Andrew J Allchorne Lynsey H Forsyth Matthew Bence Holly J Carlisle Thomas J O'Dell Rory Mitchell Seth G N Grant 《EMBO reports》2010,11(6):473-478
Sensitization to inflammatory pain is a pathological form of neuronal plasticity that is poorly understood and treated. Here we examine the role of the SH3 domain of postsynaptic density 95 (PSD95) by using mice that carry a single amino‐acid substitution in the polyproline‐binding site. Testing multiple forms of plasticity we found sensitization to inflammation was specifically attenuated. The inflammatory response required recruitment of phosphatidylinositol‐3‐kinase‐C2α to the SH3‐binding site of PSD95. In wild‐type mice, wortmannin or peptide competition attenuated the sensitization. These results show that different types of behavioural plasticity are mediated by specific domains of PSD95 and suggest novel therapeutic avenues for reducing inflammatory pain. 相似文献
980.
Jssica Freitas Araújo Encinas Carlos Henrique Foncesca Matheus Moreira Perez Diogo Pimenta Simes Beatriz da Costa Aguiar Alves Marcelo Rodrigues Bacci Laura Beatriz Mesiano Maifrino Fernando Luiz Affonso Fonseca Glaucia Luciano da Veiga 《Cell biochemistry and function》2019,37(6):443-451
Renal cells need oxygen for homeostasis; it is known for adjusting cellular functioning and the energy obtainment have a broad relationship with cellular respiration, through the O2 bioavailability. O2 homeostasis regulation in the kidney is mediated by hypoxia‐inducible factors (HIFs). HIF is divided into three α isoforms, represented by HIF‐1α, HIF‐2α, and HIF‐3α in addition to three paralogs of HIF‐1β; these are involved in some metabolic processes, as well as in the pathogenesis of several diseases. Renal biopsy analyses of patients and experimental animal models aim to understand the relationship between HIF and protection against developing renal diseases or the induction of their onset, being thus this molecule can be considered a potential biomarker of renal disease. We carried out a systematic review to which we included studies on HIF‐1α and renal disease in the last 5 years (2013‐2018) in researches with humans and/or animal model through searches in three databases: LILACS, PubMed, and SciELO by two researchers. We obtained 22 articles that discussed the relationship with HIF as inductor or protector against renal disease and no relation between HIF and renal. We observed controversies remain regarding the relation between of HIF with renal diseases; this may be related to the different intracellular pathways mediated by HIF‐1α, thereby determining differentiated cellular responses. 相似文献