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Aedes aegypti dispersion is the major reason for the increase in dengue transmission in South America. In Brazil, control of this mosquito strongly relies on the use of pyrethroids and organophosphates against adults and larvae, respectively. In consequence, many Ae. aegypti field populations are resistant to these compounds. Resistance has a significant adaptive value in the presence of insecticide treatment. However some selected mechanisms can influence important biological processes, leading to a high fitness cost in the absence of insecticide pressure. We investigated the dynamics of insecticide resistance and its potential fitness cost in five field populations and in a lineage selected for deltamethrin resistance in the laboratory, for nine generations. For all populations the life-trait parameters investigated were larval development, sex ratio, adult longevity, relative amount of ingested blood, rate of ovipositing females, size of egglaying and eggs viability. In the five natural populations, the effects on the life-trait parameters were discrete but directly proportional to resistance level. In addition, several viability parameters were strongly affected in the laboratory selected population compared to its unselected control. Our results suggest that mechanisms selected for organophosphate and pyrethroid resistance caused the accumulation of alleles with negative effects on different life-traits and corroborate the hypothesis that insecticide resistance is associated with a high fitness cost. 相似文献
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DNA barcoding Bromeliaceae: achievements and pitfalls 总被引:1,自引:0,他引:1
Background
DNA barcoding has been successfully established in animals as a tool for organismal identification and taxonomic clarification. Slower nucleotide substitution rates in plant genomes have made the selection of a DNA barcode for land plants a much more difficult task. The Plant Working Group of the Consortium for the Barcode of Life (CBOL) recommended the two-marker combination rbcL/matK as a pragmatic solution to a complex trade-off between universality, sequence quality, discrimination, and cost.Methodology/Principal Findings
It is expected that a system based on any one, or a small number of plastid genes will fail within certain taxonomic groups with low amounts of plastid variation, while performing well in others. We tested the effectiveness of the proposed CBOL Plant Working Group barcoding markers for land plants in identifying 46 bromeliad species, a group rich in endemic species from the endangered Brazilian Atlantic Rainforest. Although we obtained high quality sequences with the suggested primers, species discrimination in our data set was only 43.48%. Addition of a third marker, trnH–psbA, did not show significant improvement. This species identification failure in Bromeliaceaecould also be seen in the analysis of the GenBank''s matK data set. Bromeliaceae''s sequence divergence was almost three times lower than the observed for Asteraceae and Orchidaceae. This low variation rate also resulted in poorly resolved tree topologies. Among the three Bromeliaceae subfamilies sampled, Tillandsioideae was the only one recovered as a monophyletic group with high bootstrap value (98.6%). Species paraphyly was a common feature in our sampling.Conclusions/Significance
Our results show that although DNA barcoding is an important tool for biodiversity assessment, it tends to fail in taxonomy complicated and recently diverged plant groups, such as Bromeliaceae. Additional research might be needed to develop markers capable to discriminate species in these complex botanical groups. 相似文献104.
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Camila B. Mendes-Silverio Luiz O. S. Leiria Rafael P. Morganti Gabriel F. Anhê Sisi Marcondes Fabíola Z. Mónica Gilberto De Nucci Edson Antunes 《PloS one》2012,7(11)
Background and Aims
Nitric oxide-independent soluble guanylyl cyclase (sGC) activators reactivate the haem-oxidized enzyme in vascular diseases. This study was undertaken to investigate the anti-platelet mechanisms of the haem-independent sGC activator BAY 60-2770 in human washed platelets. The hypothesis that sGC oxidation potentiates the anti-platelet activities of BAY 60-2770 has been tested.Methods
Human washed platelet aggregation and adhesion assays, as well as flow cytometry for αIIbβ3 integrin activation and Western blot for α1 and β1 sGC subunits were performed. Intracellular calcium levels were monitored in platelets loaded with a fluorogenic calcium-binding dye (FluoForte).Results
BAY 60-2770 (0.001–10 µM) produced significant inhibition of collagen (2 µg/ml)- and thrombin (0.1 U/ml)-induced platelet aggregation that was markedly potentiated by the sGC inhibitor ODQ (10 µM). In fibrinogen-coated plates, BAY 60-2770 significantly inhibited platelet adhesion, an effect potentiated by ODQ. BAY 60-2770 increased the cGMP levels and reduced the intracellular Ca2+ levels, both of which were potentiated by ODQ. The cell-permeable cGMP analogue 8-Br-cGMP (100 µM) inhibited platelet aggregation and Ca2+ levels in an ODQ-insensitive manner. The cAMP levels remained unchanged by BAY 60-2770. Collagen- and thrombin-induced αIIbβ3 activation was markedly inhibited by BAY 60-2770 that was further inhibited by ODQ. The effects of sodium nitroprusside (3 µM) were all prevented by ODQ. Incubation with ODQ (10 µM) significantly reduced the protein levels of α1 and β1 sGC subunits, which were prevented by BAY 60-2770.Conclusion
The inhibitory effects of BAY 60-2770 on aggregation, adhesion, intracellular Ca2+ levels and αIIbβ3 activation are all potentiated in haem-oxidizing conditions. BAY 60-2770 prevents ODQ-induced decrease in sGC protein levels. BAY 60-2770 could be of therapeutic interest in cardiovascular diseases associated with thrombotic complications. 相似文献106.
Colleen R. Eade Camila Diaz Matthew P. Wood Kathryn Anastos Bruce K. Patterson Phalguni Gupta Amy L. Cole Alexander M. Cole 《PloS one》2012,7(11)
Bacterial vaginosis (BV) is the most commonly treated female reproductive tract affliction, characterized by the displacement of healthy lactobacilli by an overgrowth of pathogenic bacteria. BV can contribute to pathogenic inflammation, preterm birth, and susceptibility to sexually transmitted infections. As the bacteria responsible for BV pathogenicity and their interactions with host immunity are not understood, we sought to evaluate the effects of BV-associated bacteria on reproductive epithelia. Here we have characterized the interaction between BV-associated bacteria and the female reproductive tract by measuring cytokine and defensin induction in three types of FRT epithelial cells following bacterial inoculation. Four BV-associated bacteria were evaluated alongside six lactobacilli for a comparative assessment. While responses differed between epithelial cell types, our model showed good agreement with clinical BV trends. We observed a distinct cytokine and human β-defensin 2 response to BV-associated bacteria, especially Atopobium vaginae, compared to most lactobacilli. One lactobacillus species, Lactobacillus vaginalis, induced an immune response similar to that elicited by BV-associated bacteria, stimulating significantly higher levels of cytokines and human β-defensin 2 than other lactobacilli. These data provide an important prioritization of BV-associated bacteria and support further characterization of reproductive bacteria and their interactions with host epithelia. Additionally, they demonstrate the distinct immune response potentials of epithelial cells from different locations along the female reproductive tract. 相似文献
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Dental pulp (DP) can be extracted from child's primary teeth (deciduous), whose loss occurs spontaneously by about 5 to 12 years. Thus, DP presents an easy accessible source of stem cells without ethical concerns. Substantial quantities of stem cells of an excellent quality and at early (2-5) passages are necessary for clinical use, which currently is a problem for use of adult stem cells. Herein, DPs were cultured generating stem cells at least during six months through multiple mechanical transfers into a new culture dish every 3-4 days. We compared stem cells isolated from the same DP before (early population, EP) and six months after several mechanical transfers (late population, LP). No changes, in both EP and LP, were observed in morphology, expression of stem cells markers (nestin, vimentin, fibronectin, SH2, SH3 and Oct3/4), chondrogenic and myogenic differentiation potential, even after cryopreservation. Six hours after DP extraction and in vitro plating, rare 5-bromo-2'-deoxyuridine (BrdU) positive cells were observed in pulp central part. After 72 hours, BrdU positive cells increased in number and were found in DP periphery, thus originating a multicellular population of stem cells of high purity. Multiple stem cell niches were identified in different zones of DP, because abundant expression of nestin, vimentin and Oct3/4 proteins was observed, while STRO-1 protein localization was restricted to perivascular niche. Our finding is of importance for the future of stem cell therapies, providing scaling-up of stem cells at early passages with minimum risk of losing their "stemness". 相似文献
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Soto G Setten L Lisi C Maurelis C Mozzicafreddo M Cuccioloni M Angeletti M Ayub ND 《Extremophiles : life under extreme conditions》2012,16(3):455-462
Polyhydroxybutyrate (PHB), a typical carbon and energy storage compound, is widely found in Bacteria and Archae domains. This
polymer is produced in response to conditions of physiological stress. PHB is composed of repeating units of β-hydroxybutyrate
(R-3HB). It has been previously shown that R-3HB functions as an osmolyte in extremophile strains. In this study, Pseudomonas sp. CT13, a halotolerant bacterium, and its PHB synthase-minus mutant (phaC) were used to analyze the chaperone role of R-3HB. The production of this compound was found to be essential to salt stress
resistance and positively correlated with salt concentration, suggesting that PHB monomer acts as a compatible solute in Pseudomonas sp. CT13. R-3HB accumulation was also associated with the prevention of protein aggregation under combined salt and thermal
stresses in Pseudomonas sp. CT13. Physiological concentrations of R-3HB efficiently reduced citrate synthase (CS) aggregation and stabilized the
enzymatic activities of CS during thermal stress. Docking analysis of the CS/R-3HB interaction predicted the stability of
this complex under physiological concentrations of R-3HB. Thus, in vivo, in vitro and in silico analyses suggest that R-3HB
can act as a chemical chaperone. 相似文献