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1.
A comparative description of mitochondrial DNA differentiation in selected avian and other vertebrate genera 总被引:14,自引:1,他引:13
Levels of mitochondrial DNA (mtDNA) sequence divergence between species
within each of several avian (Anas, Aythya, Dendroica, Melospiza, and
Zonotrichia) and nonavian (Lepomis and Hyla) vertebrate genera were
compared. An analysis of digestion profiles generated by 13-18 restriction
endonucleases indicates little overlap in magnitude of mtDNA divergence for
the avian versus nonavian taxa examined. In 55 interspecific comparisons
among the avian congeners, the fraction of identical fragment lengths (F)
ranged from 0.26 to 0.96 (F = 0.46), and, given certain assumptions, these
translate into estimates of nucleotide sequence divergence (p) ranging from
0.007 to 0.088; in 46 comparisons among the fish and amphibian congeners, F
values ranged from 0.00 to 0.36 (F = 0.09), yielding estimates of P greater
than 0.070. The small mtDNA distances among avian congeners are associated
with protein-electrophoretic distances (D values) less than approximately
0.2, while the mtDNA distances among assayed fish and amphibian congeners
are associated with D values usually greater than 0.4. Since the
conservative pattern of protein differentiation previously reported for
many avian versus nonavian taxa now appears to be paralleled by a
conservative pattern of mtDNA divergence, it seems increasingly likely that
many avian species have shared more recent common ancestors than have their
nonavian taxonomic counterparts. However, estimates of avian divergence
times derived from mtDNA- and protein-calibrated clocks cannot readily be
reconciled with some published dates based on limited fossil remains. If
the earlier paleontological interpretations are valid, then protein and
mtDNA evolution must be somewhat decelerated in birds. The empirical and
conceptual issues raised by these findings are highly analogous to those in
the long-standing debate about rates of molecular evolution and times of
separation of ancestral hominids from African apes.
相似文献
2.
In the present study we used established methods to obtain apical membrane vesicles from the toad urinary bladder and incorporated these membrane fragments to solvent-free planar lipid bilayer membranes. This resulted in the appearance of a macroscopic conductance highly sensitive to the diuretic amiloride added to the cis side. The blockage is voltage dependent and well described by a model which assumes that the drug binds to sites in the channel lumen. This binding site is localized at about 15% of the electric field across the membrane. The apparent inhibition constant (K(0)) is equal to 0.98 microM. Ca2+, in the micromolar range on the cis side, is a potent blocker of this conductance. The effect of the divalent has a complex voltage dependence and is modulated by pH. At the unitary level we have found two distinct amiloride-blockable channels with conductances of 160 pS (more frequent) and 120 pS. In the absence of the drug the mean open time is around 0.5 sec for both channels and is not dependent on voltage. The channels are cation selective (PNa/PCl = 15) and poorly discriminate between Na+ and K+ (PNa/PK = 2). Amiloride decreases the lifetime in the open state of both channels and also the conductance of the 160-pS channel. 相似文献
3.
Branco S 《Molecular ecology》2010,19(24):5566-5576
Serpentine soils impose physiological stresses that limit plant establishment and diversity. The degree to which serpentine soils entail constraints on other organisms is, however, poorly understood. Here, I investigate the effect of serpentine soils on ectomycorrhizal (ECM) fungi by conducting a reciprocal transplant experiment, where serpentine and nonserpentine ECM fungal communities were cultured in both their native and non-native soils. Contrary to expectation, serpentine soils hosted higher fungal richness compared to nonserpentine, and most species were recovered from serpentine soil, suggesting ECM fungi are not overall specialized or strongly affected by serpentine edaphic constraints. 相似文献
4.
Patrícia Branco António Candeias Ana Teresa Caldeira Marina González-Pérez 《Microbial biotechnology》2019,12(6):1237-1248
Dekkera bruxellensis is the main reason for spoilage in the wine industry. It renders the products unacceptable leading to large economic losses. Fluorescence In Situ Hybridization (FISH) technique has the potential for allowing its specific detection. Nevertheless, some experimental difficulties can be encountered when FISH technique is applied in the wine environment (e.g. matrix and cells’ autofluorescence, fluorophore inadequate selection and probes’ low specificity to the target organisms). An easy and fast in-suspension RNA-FISH procedure was applied for the first time for identifying D. bruxellensis in wine. A previously designed RNA-FISH probe to detect D. bruxellensis (26S D. brux.5.1) was used, and the matrix and cells’ fluorescence interferences, the influence of three fluorophores in FISH performance and the probe specificity were evaluated. The results revealed that to apply RNA-FISH technique in the wine environment, a red-emitting fluorophore should be used. Good probe performance and specificity were achieved with 25% of formamide. The resulting RNA-FISH protocol was applied in wine samples artificially inoculated with D. bruxellensis. This spoilage microorganism was detected in wine at cell densities lower than those associated with phenolic off-flavours. Thus, the RNA-FISH procedure described in this work represents an advancement to facilitate early detection of the most dangerous wine spoilage yeast and, consequently, to reduce the economic losses caused by this yeast to the wine industry. 相似文献
5.
Microbial bioreporters offer excellent potentialities for the detection of the bioavailable portion of pollutants in contaminated environments, which currently cannot be easily measured. This paper describes the construction and evaluation of two microbial bioreporters designed to detect the bioavailable chromate in contaminated water samples. The developed bioreporters are based on the expression of gfp under the control of the chr promoter and the chrB regulator gene of TnOtChr determinant from Ochrobactrum tritici 5bvl1. pCHRGFP1 Escherichia coli reporter proved to be specific and sensitive, with minimum detectable concentration of 100 nM chromate and did not react with other heavy metals or chemical compounds analysed. In order to have a bioreporter able to be used under different environmental toxics, O. tritici type strain was also engineered to fluoresce in the presence of micromolar levels of chromate and showed to be as specific as the first reporter. Their applicability on environmental samples (spiked Portuguese river water) was also demonstrated using either freshly grown or cryo-preserved cells, a treatment which constitutes an operational advantage. These reporter strains can provide on-demand usability in the field and in a near future may become a powerful tool in identification of chromate-contaminated sites. 相似文献
6.
Chromatin remodeling is crucial for gene regulation. Remodeling is often mediated through chemical modifications of the DNA template, DNA-associated proteins, and RNA-mediated processes. Y-linked regulatory variation (YRV) refers to the quantitative effects that polymorphic tracts of Y-linked chromatin exert on gene expression of X-linked and autosomal genes. Here we show that naturally occurring polymorphisms in the Drosophila melanogaster Y chromosome contribute disproportionally to gene expression variation in the testis. The variation is dependent on wild-type expression levels of mod(mdg4) as well as Su(var)205; the latter gene codes for heterochromatin protein 1 (HP1) in Drosophila. Testis-specific YRV is abolished in genotypes with heterozygous loss-of-function mutations for mod(mdg4) and Su(var)205 but not in similar experiments with JIL-1. Furthermore, the Y chromosome differentially regulates several ubiquitously expressed genes. The results highlight the requirement for wild-type dosage of Su(var)205 and mod(mdg4) in enabling naturally occurring Y-linked regulatory variation in the testis. The phenotypes that emerge in the context of wild-type levels of the HP1 and Mod(mdg4) proteins might be part of an adaptive response to the environment. 相似文献
7.
Paulo Branco José Maria Santos Christos Katopodis António Pinheiro Maria Teresa Ferreira 《Hydrobiologia》2013,714(1):145-154
Dams and weirs strongly affect or interrupt the longitudinal connectivity of rivers, by limiting the movements of several fish species while altering and fragmenting habitats. Fishways, especially pool-type fishways, are used to diminish this impact by enabling fish to negotiate barriers. The aim of this work is to study the behaviour of a small-sized resident cyprinid fish, the Iberian chub—Squalius pyrenaicus (Günther, 1868)—within a prototype of a pool-type fishway, equipped with both surface notches and bottom orifices, and experiencing two different flow regimes, plunging and streaming. Results show that the fish tended to be more successful in their upstream movements under streaming flow and that, for this regime, the surface notch was the preferred route for upstream movements. Flow velocity patterns corroborated the results, showing that the plunging flow regime may have driven fish downstream, while the streaming flow regime may have attracted fish upstream. The plunging flow also prevented access of this surface-oriented species to the surface notch, effectively reducing the area available for transport. Thus, the streaming flow regime can be a sound option for this and other small-sized species, as it enhances fish movements through the fishway. 相似文献
8.
VP Raje PI Morgado MP Ribeiro IJ Correia VD Bonifácio PS Branco A Aguiar-Ricardo 《Biosensors & bioelectronics》2013,39(1):64-69
A water-soluble biocompatible aziridine-based biosensor with pendant anthracene units was synthesized by radicalar polymerization of N-substituted aziridines in supercritical carbon dioxide. The binding ability of the sensor towards a series of metal ions was examined by comparing the fluorescence intensities of the solutions before and after the addition of 100 equivalents of a solution of the metal ion chloride salt. A fast, simple and highly optical sensitive dual behavior, "off-on" and "on-off" response, was observed after the biosensor was exposed to the metal cations in aqueous solution. Zinc presented the highest fluorescence enhancement (turn-on) and copper presented the highest fluorescence quenching (turn-off). The response time was found to be instantaneous and the detection limit was achieved even in the presence of excess metal cation competitors. By using immunofluorescence microscopy it was also shown that oligoaziridine acts as an "on-off" probe through highly sensitive (detection limit of 1.6nM), selective and reversible binding to copper anions under physiologic conditions using living Human Fibroblast cells. The stoichiometry for the reaction of the biosensor with Cu(2+) was determined by a Job plot and indicates the formation of an oligoaziridine-Cu(2+) 1:2 adduct. 相似文献
9.
Helena M. Santos Maria‐Rosa Paiva Susana Rocha Carole Kerdelhué Manuela Branco 《Ecology and evolution》2013,3(15):5098-5108
Allochrony that is reproductive isolation by time may further lead to divergence of reproductive adaptive traits in response to different environmental pressures over time. A unique “summer” population of the pine processionary moth Thaumetopoea pityocampa, reproductively isolated from the typical winter populations by allochronic differentiation, is here analyzed. This allochronically shifted population reproduces in the spring and develops in the summer, whereas “winter” populations reproduce in the late summer and have winter larval development. Both summer and winter populations coexist in the same pine stands, yet they face different climatic pressures as their active stages are present in different seasons. The occurrence of significant differences between the reproductive traits of the summer population and the typical winter populations (either sympatric or allopatric) is thus hypothesized. Female fecundity, egg size, egg covering, and egg parasitism were analyzed showing that the egg load was lower and that egg size was higher in the summer population than in all the studied winter populations. The scales that cover the egg batches of T. pityocampa differed significantly between populations in shape and color, resulting in a looser and darker covering in the summer population. The single specialist egg parasitoid species of this moth was almost missing in the summer population, and the overall parasitism rates were lower than in the winter population. Results suggest the occurrence of phenotypic differentiation between the summer population and the typical T. pityocampa winter populations for the life‐history traits studied. This work provides an insight into how ecological divergence may follow the process of allochronic reproductive isolation. 相似文献
10.
Delfino B. M. Campos R. G. Pereira T. M. Mantovani S. A. S. Oliart-Guzmán H. Martins A. C. Braña A. M. Branco F. L. C. C. Filgueira-Júnior J. A. Santos A. P. Araújo T. S. Oliveira C. S. M. Ramalho A. A. Muniz P. T. Codeço C. T. da Silva-Nunes M. 《EcoHealth》2016,13(4):743-760
EcoHealth - This study analyzed the evolution of socioeconomic, sanitary, and personal factors as well as spatiotemporal changes in the prevalence of helminthiasis and giardiasis in urban Amazonian... 相似文献