12 research outputs found

    FKBP12 Activates the Cardiac Ryanodine Receptor Ca2+-Release Channel and Is Antagonised by FKBP12.6

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    Changes in FKBP12.6 binding to cardiac ryanodine receptors (RyR2) are implicated in mediating disturbances in Ca2+-homeostasis in heart failure but there is controversy over the functional effects of FKBP12.6 on RyR2 channel gating. We have therefore investigated the effects of FKBP12.6 and another structurally similar molecule, FKBP12, which is far more abundant in heart, on the gating of single sheep RyR2 channels incorporated into planar phospholipid bilayers and on spontaneous waves of Ca2+-induced Ca2+-release in rat isolated permeabilised cardiac cells. We demonstrate that FKBP12 is a high affinity activator of RyR2, sensitising the channel to cytosolic Ca2+, whereas FKBP12.6 has very low efficacy, but can antagonise the effects of FKBP12. Mathematical modelling of the data shows the importance of the relative concentrations of FKBP12 and FKBP12.6 in determining RyR2 activity. Consistent with the single-channel results, physiological concentrations of FKBP12 (3 µM) increased Ca2+-wave frequency and decreased the SR Ca2+-content in cardiac cells. FKBP12.6, itself, had no effect on wave frequency but antagonised the effects of FKBP12

    Sex-biased incidental mortality of albatrosses and petrels in longline fisheries: differential distributions at sea or differential access to baits mediated by sexual size dimorphism?

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    Skewed adult sex ratio (ASR) has been proposed as a common pattern in birds, frequently biased towards males and with larger biases in globally threatened species. In albatrosses and petrels, it has been suggested that differential mortality of one gender in fisheries is caused either by sexual size dimorphism giving males a competitive advantage, which allows more access of the larger sex (i.e. males) to discards and/or baits, or to at sea segregation of sexes. Here, we tested these hypotheses by determining ASRs in albatrosses and petrels trapped at sea when attending longline fishing vessels for discards in the southwestern Atlantic Ocean, and searched in the literature for patterns in ASR in albatrosses and petrels killed by fisheries in this area and elsewhere. We show that skewed ASR is common in albatrosses and petrels in the community attending vessels for discards, confirming results found for birds in general. There was no correlation between skewed ASR and conservation status, or between ASR and sexual size dimorphism. Our review of the sex of birds incidentally killed in fisheries found skewed ASR toward males, females or parity to be equally reported. Thus, sexual dimorphism in size does not explain skewed ASR in the community we sampled or in incidental captures in fisheries in the review. Differential at-sea distribution of sexes appears to be a better explanation of the patterns found in the community sampled at sea as well as skewed ASR in seabird fatalities, particularly distant from breeding areas

    Cross-Linked Chitosan-Based Hydrogels for Dye Removal

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    International audienceSynthetic dyes are a major class of recalcitrant organic compounds, often occurring in the environment as a result of their wide industrial use. More than 100,000 dyes are commercially available. Synthetic dyes are common contaminants, many of them being toxic or carcinogenic. Colored effluents from industrial plant are also perceived by the public as an indication of the presence of a dangerous pollution. Even at very low concentrations, dyes are both highly visible, inducing an esthetic pollution, and impacting the aquatic life and food chain, as a chemical pollution. Dye contamination of water is a major problem worldwide and the treatment of wastewaters before their discharge into the environment is a priority. Dyes are difficult to treat due to their complex aromatic structure and synthetic origin. In general, a combination of different physical, chemical and biological processes is often used to obtain the desired water quality. However, there is a need to develop new removal strategies and decolorization methods that are more effective, acceptable in industrial use, and ecofriendly. Currently, there is an increasing interes
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