Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

New insights on the nitrogen footprint of a coastal megalopolis from coral-hosted Symbiodinium δ15N

The development of megalopolises in coastal areas is often linked with severe eutrophication, requiring mitigation of anthropogenic dissolved inorganic nitrogen (DIN) pollution. Yet, identifying the DIN-sources responsible for eutrophication is challenging, hampering mitigation efforts. Here, we utilize the stable nitrogen isotope ratio of endosymbiotic dinoflagellate Symbiodinium spp. (δ15Nsym) associated with the hard coral Porites to trace DIN sources in one of the most urbanized areas of the planet: the Pearl River Delta (PRD). The mean δ15Nsym value found in the coastal waters of Hong Kong (HK), located on the eastern edge of the PRD, (7.4‰ ± 1.2‰) was +2.7‰ higher than at Dongsha Atoll, a reference site unaffected by anthropogenic-DIN (4.7‰ ± 0.4‰). The isotopic enrichment suggested a consistent dominance of DIN deriving from local and regional sewage discharges on the eastern edge of HK. Furthermore, the strong depletion of the summer δ15Nsym value (−1.6‰) observed in southern HK revealed that the Pearl River plume strongly modulates the coastal DIN pool. Our results revealed the value of benthic marine organisms’ δ15N for deciphering the complex dynamics of coastal eutrophication and highlighted the pivotal role of transboundary coordination in DIN-pollution mitigation

Coral isoscapes reveal varied nitrogen sources and dynamics in Hong Kong’s coastal environment

Poster Presentation: Session #:09 - Abstract ID: 29155 ; Poster ID: 92Hong Kong's marine ecosystem health is under threat due to large inputs of dissolved inorganic nitrogen (DIN) from various sources. We used stable isotope analysis to trace major DIN source(s) affecting corals and examined their spatial and temporal variations in coastal environments. We collected corals along coastlines in a wet and dry season and analyzed the δ15N signals of their Symbiodinium (δ15Ns). Spatially, the mean δ15Ns value was significantly lower in the Southern zone–SHK (5.6±1.5‰) than Northeastern zones–PS (8.0±1.1‰) and MB (8.8±1.3‰) in the wet season. In the dry season, there was no significant difference in the mean δ15Ns values among zones. When compared between seasons, the mean δ15Ns value in SHK in the dry season (6.9±0.7‰) was significantly higher than the wet season. The spatial and seasonal differences in the δ15Ns values highlighted the influence of the Pearl River (PR), which supplies Hong Kong with a high concentration of 14N compared to N derived from oceanic water. The dominance of N from PR could contribute to the low δ15Ns values in SHK in the wet season as it is in close proximity to PR. The seasonal difference, i.e. higher δ15Ns values in SHK in the dry than wet season, can be explained by the decreasing influence of PR as the dry season accounts for ~20% of the annual discharge. These data suggested PR has a major influence to the DIN dynamics and its significance is subject to spatial and seasonal changes

Reefs of the future: Water quality constrains coral biodiversity in an urbanized seascape

abstract no. COS 127-9Background/Question/Methods As foundational species, corals provide a complex habitat that hosts an immense diversity of marine life. Yet, globally corals are in a perilous decline leading to loss of biodiversity and ecosystem services. To date, the relative importance of global (e.g. climate change, acidification) versus local (e.g. overfishing, pollution) are still hotly debated. This debate is rife with shifting baselines, because reef degradation often preceded science and management efforts. Increasingly, studies are focusing on natural (e.g. CO2 seeps) or anthropogenic (e.g. power plant effluent) gradients to test the hypothesis that global change processes are decreasing coral diversity. Yet, few studies have examined how water quality affects coral species richness. Hong Kong is host to more than 80 hard coral species, which cling to the edges of strong water quality gradients across a limited spatial scale. Owing to more than 20 years of water quality and coral diversity monitoring, Hong Kong provides an interesting scenario to test the hypothesis that poor water quality reduces coral species richness. This GIS and field-based study investigates the effect of five water quality parameters (total inorganic nitrogen & phosphate, particulate suspended matter, salinity and dissolved oxygen) on hard coral species richness. Results/Conclusions Coral species richness was negatively correlated with surface productivity (chla). Both nitrogen and phosphorus were negatively correlated with coral diversity and had twice the relative importance as particulate suspended matter. These negative effects were ground-truthed in an explantation experiment along a water quality gradient emanating from a heavily urbanized watershed. Corals growing near sewage effluents suffered high mortality, whereas corals further away showed increasing survivorship and growth. Taken together, we can use these data to identify biodiversity hot-spots and water quality thresholds for hard coral diversity to better inform future MPA and restoration site selection

Not all corals dine in: variation in niche partitioning between corals and their Symbiodinium indicates a range of symbioses

Oral presentation - Session #:11: Abstract ID: 29304The symbiosis between corals and Symbiodinium has allowed coral reefs to achieve high levels of productivity and diversity in oligotrophic habitats. By sharing resources, corals and Symbiodinium access novel niche space. Some have argued that the coral-algal interaction ranges from mutualism to parasitism. Trophic niche theory predicts that mutualist symbionts would occupy the same niche space as their host (shared resources) whereas commensal symbionts would occupy a different niche (fewer shared resources). To test this hypothesis, we measured the δ13C and δ15N of separated coral tissue and symbiont cells from 6 coral genera commonly encountered in Hong Kong. Using Stable Isotope Bayesian Ellipses in R (SIBER) analysis, we compared the isotopic niche placement and area of each host and symbiont pair. Our results supported the hypothesis: in some genera (Acropora and Goniopora) the host and symbiont had nearly 100% overlap of their isotopic niches implying shared nutritional resources, while in others (Platygyra and Favites) there was no overlap. Finally, some genera (Pavona and Porites) have partial overlap suggesting a flexible symbiosis. These patterns were driven by nitrogen, not carbon. Indeed, the difference between the δ15N values of host and symbiont was positively correlated with calyx volume, suggesting that smaller polyps evolved to support obligate symbioses while larger polyps enable corals to meet their nutritional requirements through alternative means

A Pilot Study on the Efficacy of Volunteer Mentorship for Young Adults With Self-Harm Behaviors Using a Quasi-Experimental Design

Background: Studies have shown that postdischarge care for self-harm patients is effective in reducing repeated suicidal behaviors. Little is known about whether volunteer support can help reduce self-harm repetition and improve psychosocial well-being. Aim: This study investigated the efficacy of volunteer support in preventing repetition of self-harm. Method: This study used a quasi-experimental design by assigning self-harm patients admitted to the emergency departments to an intervention group with volunteer support and treatment as usual (TAU) for 9 months and to a control group of TAU. Outcome measures include repetition of self-harm, suicidal ideation, hopelessness, and level of depressive and anxiety symptoms. Results: A total of 74 cases were recruited (38 participants; 36 controls). There were no significant differences in age, gender, and clinical condition between the two groups at the baseline. The intervention group showed significant improvements in hopelessness and depressive symptoms. However, the number of cases of suicide ideation and of repetition of self-harm episodes was similar for both groups at the postintervention period. Conclusion: Postdischarge care provided by volunteers showed significant improvement in hopelessness and depression. Volunteers have been commonly involved in suicide prevention services. Further research using rigorous methods is recommended for improving service quality in the long term

Stable N isotopes reveal the sources of nitrogen affecting Hong Kong’s coral communities

Marine ecosystems have experienced dramatic changes since the 1850s in response to human activities. This epoch, often referred to as the Anthropocene, has witnessed the punctuated loss of reef-building corals worldwide. Coral reef degradation may induce subtle changes which remain un-witnessed; this is particularly true when the water quality is altered. Deteriorated water quality, in particular due to nitrogen enrichment, hampers coral larvae recruitment, amplifies bio-erosion, favors coral diseases and reduces the threshold of thermal bleaching, leading to local or regional coral species extinctions. Hong Kong SAR waters host more than 80 hard coral species which occur under N concentrations above the eutrophication threshold of ~1 µmol.l-1. A GIS-based study revealed that the hard coral species richness distribution followed the nutrient concentrations (nitrogen and phosphorus). N & P concentration appeared to be the main drivers of coral species richness. Identifying the nutrients sources affecting HK’s communities is thus crucial to implement N-mitigation policies in order to preserve hard coral biodiversity. The δ15N signature of hard coral tissues collected over 30 sites identified two main N-sources. Some 15N-depleted N is coming from the Pearl River delta area, possibly reflecting fertilizers-derived-N, whereas 15N-enriched N is found on eastern coral communities, suggesting a more local N source: most likely sewage. The N-sources identified in the present study provide a useful baseline for the conservation and the management of local coral communities but also of eutrophied coral ecosystems worldwide