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221.
Exocytotic release from individual granules exhibits similar properties at mast and chromaffin cells. 总被引:3,自引:0,他引:3
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The effects of temperature on granular secretion were studied in individual bovine adrenal chromaffin and rat peritoneal mast cells. It was found that more molecules are released from individual granules at physiological temperature than at room temperature, where such experiments are normally performed. In mast cells, there is also a dramatic decrease in the time required for exocytosis to be complete at 37 degrees C compared to room temperature. In the presence of some cations, the amount released from individual granules at room temperature from both types of cells could be altered. The amount of secretion decreased with the divalent cation zinc but increased with the monovalent cation cesium. These experiments used two electrochemical techniques: cyclic voltammetry and amperometry. With amperometry, the concentration gradient created by the electrode near the cell further increased the amount of release. Similar responses to changes in the extracellular environment in chromaffin and mast cells suggest that the mechanism of extrusion of the granule contents is similar in both cell types. 相似文献
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223.
Henrique O. Sawakuchi David Bastviken André O. Sawakuchi Nicholas D. Ward Clovis D. Borges Siu M. Tsai Jeffrey E. Richey Maria Victoria R. Ballester Alex V. Krusche 《Global Change Biology》2016,22(3):1075-1085
The flux of methane (CH4) from inland waters to the atmosphere has a profound impact on global atmospheric greenhouse gas (GHG) levels, and yet, strikingly little is known about the dynamics controlling sources and sinks of CH4 in the aquatic setting. Here, we examine the cycling and flux of CH4 in six large rivers in the Amazon basin, including the Amazon River. Based on stable isotopic mass balances of CH4, inputs and outputs to the water column were estimated. We determined that ecosystem methane oxidation (MOX) reduced the diffusive flux of CH4 by approximately 28–96% and varied depending on hydrologic regime and general geochemical characteristics of tributaries of the Amazon River. For example, the relative amount of MOX was maximal during high water in black and white water rivers and minimal in clear water rivers during low water. The abundance of genetic markers for methane‐oxidizing bacteria (pmoA) was positively correlated with enhanced signals of oxidation, providing independent support for the detected MOX patterns. The results indicate that MOX in large Amazonian rivers can consume from 0.45 to 2.07 Tg CH4 yr?1, representing up to 7% of the estimated global soil sink. Nevertheless, climate change and changes in hydrology, for example, due to construction of dams, can alter this balance, influencing CH4 emissions to atmosphere. 相似文献
224.
Geísa Pinheiro Paes José Marcelo Soriano Viana Fabyano Fonseca e Silva Gabriel Borges Mundim 《Genetics and molecular biology》2016,39(1):97-110
The objectives of this study were to assess linkage disequilibrium (LD) and selection-induced changes in single nucleotide polymorphism (SNP) frequency, and to perform association mapping in popcorn chromosome regions containing quantitative trait loci (QTLs) for quality traits. Seven tropical and two temperate popcorn populations were genotyped for 96 SNPs chosen in chromosome regions containing QTLs for quality traits. The populations were phenotyped for expansion volume, 100-kernel weight, kernel sphericity, and kernel density. The LD statistics were the difference between the observed and expected haplotype frequencies (D), the proportion of D relative to the expected maximum value in the population, and the square of the correlation between the values of alleles at two loci. Association mapping was based on least squares and Bayesian approaches. In the tropical populations, D-values greater than 0.10 were observed for SNPs separated by 100-150 Mb, while most of the D-values in the temperate populations were less than 0.05. Selection for expansion volume indirectly led to increase in LD values, population differentiation, and significant changes in SNP frequency. Some associations were observed for expansion volume and the other quality traits. The candidate genes are involved with starch, storage protein, lipid, and cell wall polysaccharides synthesis. 相似文献
225.
A. Bain R. M. Borges M. H. Chevallier H. Vignes N. Kobmoo Y. Q. Peng A. Cruaud J. Y. Rasplus F. Kjellberg M. Hossaert-Mckey 《Evolutionary ecology》2016,30(4):663-684
Ficus and their mutualistic pollinating wasps provide a unique model to investigate joint diversification in a high dispersal system. We investigate genetic structuring in an extremely wide-ranging Ficus species, Ficus racemosa, and its pollinating wasp throughout their range, which extends from India to Australia. Our samples were structured into four large, vicariant populations of figs and wasps which may correspond to distinct (sub)species, located in India, China-Thailand, Borneo, and Australia. However, the genetically most divergent group was the Indian population for the figs and the China-Thailand population for the wasps, suggesting different evolutionary histories of populations. Molecular dating for the wasps shows that diversification of the pollinator clade is surprisingly old, beginning about 13.6 Ma. Data on both the host fig species and its pollinating wasps suggest that strong genetic flow within biogeographic groups over several hundreds of kilometers has limited genetic and morphological differentiation and, potentially, local adaptation. This is probably due to long-distance dispersal of pollinating wasps. The genetic clustering into large geographic units observed in F. racemosa and its pollinators is reminiscent of what can be observed in some other high-dispersal organisms characterized by morphology that varies little over huge distances. The implications of strong gene flow for diversification processes and adaptation to different ecological conditions in Ficus and their pollinating wasps are just beginning to emerge. 相似文献
226.
Andriéli Borges Santos Andressa Silva Fernandes Roger Wagner Eduardo Jacob-Lopes Leila Queiroz Zepka 《Journal of applied phycology》2016,28(3):1561-1570
The objective of this study was to investigate the volatile organic compounds (VOCs) produced from heterotrophic cultivation of the cyanobacterium Phormidium autumnale with different sources of monosaccharides. The volatiles were isolated by headspace solid-phase micro-extraction in different residence times, separated by gas chromatography, and identified by mass spectrometry (SPME-GC/MS). The profile of volatiles contained a total of 44 volatile compounds when P. autumnale was grown heterotrophically on glucose and 35 when grown on fructose. A combined total of 68 compounds was identified and 11 volatiles were common to both extracts. The compound 3-methyl-butanol was identified among the major volatile compounds formed, reaching a concentration of 141.5 μg mg?1 dry weight for the glucose-grown cultures and 69.5 μg mg?1 for the fructose-grown cultures after 144 h. Many of the compounds detected during heterotrophic cultivation originated from terpenoids (β-ionone, β-cyclocitral, and 5,6-epoxy-β-ionone), fatty acids (hexanol, hexanal), or the 2-keto acid pathway (3-methyl-butanol, propanol, butanol). 相似文献
227.
228.
Skeletochronological estimation of age and growth of loggerhead sea turtles (Caretta caretta) in the western South Atlantic Ocean
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Ana Júlia Lenz Larisa Avens Cariane Campos Trigo Márcio Borges‐Martins 《Austral ecology》2016,41(5):580-590
Age and growth are important parameters for better understanding of life history and population dynamics of animal species, as well as for formulating management strategies. However, these data are difficult to obtain for sea turtles because of overall slow growth, delayed maturation and highly migratory behaviour. The loggerhead sea turtle, Caretta caretta, is a widely distributed species, globally listed as endangered. Although the species has been well‐studied in some regions, little is known about various aspects of its biology in other populations, such as those in the waters of the western South Atlantic Ocean, especially outside nesting areas. To address age and growth, loggerhead turtles found dead stranded on the northern coast of the state of Rio Grande do Sul during a period of 16 years (1994–2010) were utilized for estimation of age and growth rates using skeletochronology. The individuals analyzed were predominantly neritic juveniles, ranging from 53 to 101 cm curved carapace length (CCL; mean = 71 cm), with estimated ages between 10 and 29 years (mean = 15 years). Mean estimated annual growth rate was 2.1 cm CCL year?1 (1.9 cm SCL yr?1), showing large variation among individuals and between successive years in the same individual. Generalized additive mixed models analysis indicated that growth response was influenced by age, CCL and year. The results demonstrated that the southern coast of Brazil is an important area for the development of neritic juveniles of this species, which appear to recruit to this region beginning at about 12 years of age and sizes greater than 55 cm CCL. 相似文献
229.
Mauro Maciel de Arruda Fabiano Borges Figueiredo Andreza Pain Marcelino José Ronaldo Barbosa Guilherme Loureiro Werneck Elza Ferreira Noronha Gustavo Adolfo Sierra Romero 《Memórias do Instituto Oswaldo Cruz》2016,111(3):168-173
In Brazil, human and canine visceral leishmaniasis (CVL) caused byLeishmania
infantum has undergone urbanisation since 1980, constituting a public
health problem, and serological tests are tools of choice for identifying infected
dogs. Until recently, the Brazilian zoonoses control program recommended
enzyme-linked immunosorbent assays (ELISA) and indirect immunofluorescence assays
(IFA) as the screening and confirmatory methods, respectively, for the detection of
canine infection. The purpose of this study was to estimate the accuracy of ELISA and
IFA in parallel or serial combinations. The reference standard comprised the results
of direct visualisation of parasites in histological sections, immunohistochemical
test, or isolation of the parasite in culture. Samples from 98 cases and 1,327
noncases were included. Individually, both tests presented sensitivity of 91.8% and
90.8%, and specificity of 83.4 and 53.4%, for the ELISA and IFA, respectively. When
tests were used in parallel combination, sensitivity attained 99.2%, while
specificity dropped to 44.8%. When used in serial combination (ELISA followed by
IFA), decreased sensitivity (83.3%) and increased specificity (92.5%) were observed.
Serial testing approach improved specificity with moderate loss in sensitivity. This
strategy could partially fulfill the needs of public health and dog owners for a more
accurate diagnosis of CVL. 相似文献