Lipopolysaccharide (LPS) induces apoptosis in murine macrophages through the autocrine secretion of tumor necrosis factor (TNF)-α and nitric oxide (NO). LPS-induced inflammation in murine macrophages is associated with hydrogen sulfide (H2S) production. In this present study, we reported the novel role of H2S in LPS-induced apoptosis and its underlying molecular mechanism specifically at late phases in murine macrophage cells. Stimulation of RAW 264.7 macrophages with LPS resulted in a time- and dose-dependent induction of apoptosis. We observed that the LPS-induced early apoptosis (associated with TNF-α secretion) in macrophages was not inhibited in the presence of H2S inhibitor (DL-propargylglycine), whereas early apoptosis was absent in the presence of TNF receptor antibody. Interestingly, LPS-induced late apoptosis paralleled with H2S production was reduced in the presence of H2S inhibitor but not with TNF receptor antibody. The late apoptotic events mediated by H2S and not the TNF-α induced early apoptosis correlated significantly with the induction of p53 and Bax expression in LPS-induced macrophages. Thus, it is possible that RAW 264.7 murine macrophages treated with LPS mediated early apoptosis through TNF-α and the late apoptotic events through the production of H2S.
Impaction of food usually occurs in patients having obstructive lesions of the oesophagus. The food bolus impaction normally occurs in patients older than 60 years of age. Though food bolus impaction in the oesophagus is not uncommon, food bolus in the oesophagus causing complete obstruction resulting in total dysphagia is rare. This is a case report of a woman who had complete obstruction of the oesophagus following impaction by a piece of meat. The various treatment modalities available for such a condition are discussed.
While wetlands are the largest natural source of methane (CH4 ) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi-site synthesis of how predictors of CH4 fluxes (FCH4) in freshwater wetlands vary across wetland types at diel, multiday (synoptic), and seasonal time scales. We used several statistical approaches (correlation analysis, generalized additive modeling, mutual information, and random forests) in a wavelet-based multi-resolution framework to assess the importance of environmental predictors, nonlinearities and lags on FCH4 across 23 eddy covariance sites. Seasonally, soil and air temperature were dominant predictors of FCH4 at sites with smaller seasonal variation in water table depth (WTD). In contrast, WTD was the dominant predictor for wetlands with smaller variations in temperature (e.g., seasonal tropical/subtropical wetlands). Changes in seasonal FCH4 lagged fluctuations in WTD by ~17 ± 11 days, and lagged air and soil temperature by median values of 8 ± 16 and 5 ± 15 days, respectively. Temperature and WTD were also dominant predictors at the multiday scale. Atmospheric pressure (PA) was another important multiday scale predictor for peat-dominated sites, with drops in PA coinciding with synchronous releases of CH4 . At the diel scale, synchronous relationships with latent heat flux and vapor pressure deficit suggest that physical processes controlling evaporation and boundary layer mixing exert similar controls on CH4 volatilization, and suggest the influence of pressurized ventilation in aerenchymatous vegetation. In addition, 1- to 4-h lagged relationships with ecosystem photosynthesis indicate recent carbon substrates, such as root exudates, may also control FCH4. By addressing issues of scale, asynchrony, and nonlinearity, this work improves understanding of the predictors and timing of wetland FCH4 that can inform future studies and models, and help constrain wetland CH4 emissions.
Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries.
A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities.