Memorial University of Newfoundland

About: Memorial University of Newfoundland is a education organization based out in St. John's, Newfoundland and Labrador, Canada. It is known for research contribution in the topics: Population & Context (language use). The organization has 13818 authors who have published 27785 publications receiving 743594 citations. The organization is also known as: Memorial University & Memorial University of Newfoundland and Labrador.

Geochemistry of bimodal basalt-subalkaline/peralkaline rhyolite provinces within the Southern British Caledonides

Abstract: Bimodal associations of basalt and rhyolite of Upper Ordovician age which were erupted in a submarine environment occur within the Caledonian orogenic belt of South Britain at Parys Mountain (Anglesey), in Snowdonia (North Wales) and at Avoca (SE Ireland). The volcanic rocks have experienced hydrothermal alteration and low-grade metamorphism, and therefore immobile elements (e.g. Ti, Zr, Nb, Y) have been used to identify the original geochemical characteristics. The basalts have characters transitional between volcanic ‘arc’ and ‘within plate’ types consistent with eruption on an extensional part of an active continental margin. Two groups of rhyolites have been identified. A low-Zr group (Zr 500ppm), represented at Snowdonia and Avoca, is interpreted as originally being peralkaline in composition; their high Zr/Nb ratios (>10) are typical of peralkaline rhyolites erupted above subduction zones. The bimodal nature of the associations and the peralkaline character of some rhyolites indicates magma production in a complex tectonic setting, transitional between an active continental margin/island arc and an extensional environment. Associated sulphide mineralization is volcanogenic and probably syn-sedimentary. High-level, rhyolitic magma chambers are thought to have driven convection of the hydrothermal fluids from which the sulphides precipitated.

Appetite-Controlling Endocrine Systems in Teleosts

Abstract: Mammalian studies have shaped our understanding of the endocrine control of appetite and body weight in vertebrates and provided the basic vertebrate model that involves central (brain) and peripheral signaling pathways as well as environmental cues. The hypothalamus has a crucial function in the control of food intake, but other parts of the brain are also involved. The description of a range of key neuropeptides and hormones as well as more details of their specific roles in appetite control continues to be in progress. Endocrine signals are based on hormones that can be divided into two groups: those that induce (orexigenic), and those that inhibit (anorexigenic) appetite and food consumption. Peripheral signals originate in the gastrointestinal (GI) tract, liver, adipose tissue and other tissues and reach the hypothalamus through both endocrine and neuroendocrine actions. While many mammalian-like endocrine appetite-controlling networks and mechanisms have been described for some key model teleosts, mainly zebrafish and goldfish, very little knowledge exists on these systems in fishes as a group. Fishes represent over 30000 species and there is a large variability in their ecological niches and habitats as well as life history adaptations, transitions between life stages and feeding behaviors. In the context of food intake and appetite control, common adaptations to extended periods of starvation or periods of abundant food availability are of particular interest. This review summarizes the recent findings on endocrine appetite controlling systems in fish, highlights their impact on growth and survival, and discusses the perspectives in this research field to shed light on the intriguing adaptations that exist in fish and their underlying mechanisms.