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Aim: Exploring the relationships between the different facets of beta diversity and both past and current environmental conditions can unveil the processes that have shaped spatial patterns of biodiversity. In the marine realm, large‐scale patterns and processes of beta diversity have been less investigated. Our study aimed to investigate the patterns and drivers of multiple facets of beta diversity and its components, contrasting pairs of reef fish assemblages among marine realms. Location: Tropical reefs. Taxon: Reef fishes. Methods: Based on trait data and phylogenetic relationships for 5182 tropical reef fish species, we calculated compositional differences between pairs of reef fish assemblages across the Atlantic, the Tropical Eastern Pacific (TEP) and the Indo‐Pacific realms. We also applied a partitioning approach to distinguish between the turnover and nestedness components. We then evaluated the relative importance of several variables related to historical and contemporary environmental conditions in shaping spatial patterns of beta diversity using Constrained Analysis of Principal coordinates (CAP) models. Results: Both the turnover and the nestedness components contributed to total phylogenetic and taxonomic beta diversity in the TEP and Indo‐Pacific realms, while the turnover component was found to be more important in the Atlantic realm. In contrast, total trait beta diversity displayed very low values and was primarily explained by the nestedness component. Taxonomic and phylogenetic differences in the composition of tropical reef fish assemblages were influenced by both historical and contemporary factors or solely by historical variables. Main conclusions Our results suggest that past climate changes and historical contingency left an imprint in the present‐day composition of tropical reef fish assemblages. The very low levels of trait beta diversity indicate that reef fish assemblages display similar trait composition even among geographically distant assemblages with contrasting evolutionary histories, which may result from environmental filtering or evolutionary convergence, or the combination of both processes. [ABSTRACT FROM AUTHOR]

Abstract: The present study examines possible mechanisms by which the flavonoid isokaempferide (IKPF; 5,7,4′-trihydroxy-3-methoxyflavone) from Amburana cearensis, a Brazilian medicinal plant popularly used as bronchodilator, induces relaxation of guinea-pig isolated trachea. In the trachea (with intact epithelium) contracted by carbachol, IKPF (1–1000 μM) caused a graded relaxation, and the epithelium removal increased the sensitivity of the airway smooth muscle to IKPF (EC50, in intact tissue: 77.4 [54.8–109.2] μM; in denuded epithelium: 15.0 [11.3–20.1] μM). The IKPF-induced relaxation was inhibited in 41% by the nitric oxide (NO) synthase inhibitor l-NAME (100 μM); in 31% and 50% by the soluble guanylate cyclase (sGC) inhibitor ODQ (3 and 33 μM); by propranolol (31%) and also by capsaicin (37%). In the trachea pre-contracted by 40 mM KCl the pre-incubation with glibenclamide (33 μM) or iberiotoxin (IbTX, 0.1 μM), selective K+ channel inhibitors, inhibited the IKPF-induced relaxation by 39% and 38%, respectively. On the other hand, 4-aminopyridine (100 μM), a nonselective K+ channel antagonist, did not significantly influence the effect of IKPF, while IbTX induced a rightward displacement of the IKPF concentration–response curve. However, in muscle pre-contracted with 120 mM KCl the relaxant effect of IKPF was significantly reduced and not affected by glibenclamide. In conclusion, these results indicate a direct and epithelium-independent relaxant effect of IKPF on smooth muscle fibers. Although this IKPF relaxant action seems to be multi-mediated, it occurs via both Ca2+ and ATP-sensitive K+ channels, but some other possible mechanisms unrelated to K+ channels cannot be excluded. [Copyright &y& Elsevier]

The Argentinean Patagonia berries Berberis microphylla, Berberis darwinii, and Fragaria chiloensis ssp. chiloensis f. patagonica were investigated for their polyphenol content and composition by means of liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry. The in vitro antioxidant activity and inhibition of metabolic syndrome-associated enzymes (α-glucosidase, α-amylase, and lipase) of the fruit extracts was assessed. The most complex polyphenol profile was found in the Berberis samples, with 10 anthocyanins, 27 hydroxycinnamic acids, 3 proanthocyanidins, 2 flavan-3-ol, and 22 flavonols. Fragaria presented four anthocyanins, nine ellagitannins, two proanthocyanidin dimers, one flavan-3-ol, and five flavonols. The Berberis samples showed the best antioxidant capacity, while Fragaria displayed better activity against α-glucosidase and lipase. The phenolic content and composition of the Argentinean Patagonia berries was similar to that reported for Chilean samples but with some chemical differences between Eastern (Argentina) and Western (Chile) Patagonia. The data obtained supports the consumption of these berries as sources of beneficial polyphenols. [ABSTRACT FROM AUTHOR]

The mechanisms determining exercise intolerance are poorly understood. A reduction in work efficiency in the form of an additional energy cost and oxygen requirement occurs during high-intensity exercise and contributes to exercise limitation. Muscle fatigue and subsequent recruitment of poorly efficient muscle fibres has been proposed to mediate this decline. These data demonstrate in humans, that muscle fatigue, generated in the initial minutes of exercise, is correlated with the increasing energy demands of high-intensity exercise. Surprisingly, however, while muscle fatigue reached a plateau, oxygen uptake continued to increase throughout 8 min of exercise. This suggests that additional recruitment of inefficient muscle fibres may not be the sole mechanism contributing to the decline in work efficiency during high-intensity exercise. [ABSTRACT FROM AUTHOR]

Highlights: [•] Proteomic analysis showed 57 distinct proteins LbWTS vs LbSbR and LcWTS vs LcSbR. [•] Proteins of antioxidant defense, stress and metabolism were differentially expressed. [•] TRYP, α-tubulin, HSP70, HSP83, and HSP60 were overexpressed in LbSbR and LcSbR lines. [•] CyPA is less expressed in LbSbR and LcSbR lines and PTR1 is higher in the LbSbR line. [•] Mechanism of antimony-resistance in Leishmania spp. is complex and multifactorial. [ABSTRACT FROM AUTHOR]

Astrocytes provide structural and metabolic support for neuronal networks, but direct evidence demonstrating their active role in complex behaviors is limited. Central respiratory chemosensitivity is an essential mechanism that, via regulation of breathing, maintains constant levels of blood and brain pH and partial pressure of CO2. We found that astrocytes of the brainstem chemoreceptor areas are highly chemosensitive. They responded to physiological decreases in pH with vigorous elevations in intracellular Ca2+ and release of adenosine triphosphate (ATP). ATP propagated astrocytic Ca2+ excitation, activated chemoreceptor neurons, and induced adaptive increases in breathing. Mimicking pH-evoked Ca2+ responses by means of optogenetic stimulation of astrocytes expressing channelrhodopsin-2 activated chemoreceptor neurons via an ATP-dependent mechanism and triggered robust respiratory responses in vivo. This demonstrates a potentially crucial role for brain glial cells in mediating a fundamental physiological reflex. [ABSTRACT FROM AUTHOR]