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

Faunal assemblages of seagrass ecosystems

Seagrass habitats support diverse animal assemblages and while there has been considerable progress in the study of these fauna over the last few decades, large knowledge gaps remain. There are biases in our knowledge of taxonomic and functional information that favour the temperate regions over the tropics, some seagrass genera over others, shallow habitats compared to deeper meadows and larger animals over smaller ones, with many invertebrate communities poorly described. In many areas of Australia, invertebrate identification to low taxonomic resolution is difficult due to a lack of resources, but new approaches, such as genetic barcoding, may one day surpass traditional methods of classification and overcome this issue. Many studies have demonstrated greater biodiversity of fauna in seagrass compared to adjacent bare habitats with explanations for this ranging from habitat and seascape processes to food availability and trophic interactions. Within seagrass ecosystems, meadows can be highly heterogeneous, and habitat factors such as structural complexity, patch size, edges, gaps and corridors influence associated faunal communities. Broader seascape processes that occur across multiple connected habitats, including seagrass meadows, bare sediments, mangroves, saltmarshes and coral and rocky reefs, influence faunal productivity and/or diversity through the movement of organisms for recruitment and migration, and the transport of detritus and nutrients. The study of seagrass food webs has highlighted the importance of bottom-up processes in shaping the faunal assemblages through assessments of the role of invertebrate prey in influencing the productivity of consumer species and manipulative experiments that show prey resources affecting spatial patterns of predators. In addition, top-down consumptive and non-consumptive effects of predators such as their modification of prey behaviour also affect the structure of faunal communities. A large number of natural and anthropogenic perturbations to seagrass meadows influence their resident animals. These disturbances can modify seagrass-associated fauna in several ways; directly where seagrass fauna are more sensitive to perturbation than their seagrass habitat, indirectly through habitat modification, and additionally through interventions that reduce connectivity between habitats that fauna use for part of their life cycle. Animals can also play a significant role in structuring seagrass meadows through processes such as herbivory and bioturbation that can have both positive and negative effects on seagrass habitat