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.

Genomic islands of divergence and their consequences for the resolution of spatial structure in an exploited marine fish

Abstract: As populations diverge, genomic regions associated with adaptation display elevated differentiation. These genomic islands of adaptive divergence can inform conservation efforts in exploited species, by refining the delineation of management units, and providing genomic tools for more precise and effective population monitoring and the successful assignment of individuals and products. We explored heterogeneity in genomic divergence and its impact on the resolution of spatial population structure in exploited populations of Atlantic cod, Gadus morhua, using genome wide expressed sequence derived single nucleotide polymorphisms in 466 individuals sampled across the range. Outlier tests identified elevated divergence at 5.2% of SNPs, consistent with directional selection in one-third of linkage groups. Genomic regions of elevated divergence ranged in size from a single position to several cM. Structuring at neutral loci was associated with geographic features, whereas outlier SNPs revealed genetic discontinuities in both the eastern and western Atlantic. This fine-scale geographic differentiation enhanced assignment to region of origin, and through the identification of adaptive diversity, fundamentally changes how these populations should be conserved. This work demonstrates the utility of genome scans for adaptive divergence in the delineation of stock structure, the traceability of individuals and products, and ultimately a role for population genomics in fisheries conservation.

Antioxidant Activity of Green Tea and Its Catechins in a Fish Meat Model System

Abstract: The antioxidant activity of ground green tea (GGT) and commercial tea extracts, namely Polyphenon 25 (P-25), Polyphenon 30 (P-30), Polyphenon 60 (P-60), and Nikken Polyphenon 60 (NPP-60), as well as green tea extracts (GTE) prepared on laboratory scale and pure tea catechins, namely, (−)-epicatechin (EC), (−)- epigallocatechin (EGC), (−)-epicatechin gallate (ECG), and (−)-epigallocatechin gallate (EGCG), in a fish meat model system was evaluated. Results so obtained were compared with those of samples containing commonly used antioxidants such as α-tocopherol, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and tert-butylhydroquinone (TBHQ). The ground white muscle of mackerel (model system) was cooked at 75 °C and stored at 4 °C for 7 days. Progression of oxidation was monitored by measuring changes in the 2-thiobarbituric acid-reactive substances and selected and/or total volatile contents of samples. The samples treated with GGT leaves, tea extracts, and pure catechins showed excellent ...

Partial Melting in the Higher Himalayan Crystallines of Eastern Nepal: the Effect of Decompression and Implications for the ‘Channel Flow’ Model

Abstract: Partial melting of deep continental crust may occur during either prograde heating or decompression. Although the effect of temperature on crustal melting has been widely investigated, few experimental studies have addressed the question of the influence of pressure on crustal anatexis.Tounderstand the influenceofdecreasingpressure onpartialmelting processes, the thermodynamic approach of isochemical phase diagrams has been applied to garnet^K-feldspar^kyanite^sillimanite anatectic gneisses (Barun Gneiss) from the Higher Himalayan Crystallines (HHC)ofeasternNepal.Themainmelt-producing reactions, the amount of melt produced during heating vs decompression, and the effects ofmelt loss on themineral assemblagesand compositions have been investigated along four idealP^T trajectories, dominated by either heating or decompression. Based on these results, the observed microstructures and mineral compositions of the Barun Gneiss have beeninterpreted intermsofmelt-producingvsmelt-consumingreactions (e.g. growth ofperitecticgarnetwith preserved ‘nanogranite’inclusions vs microstructures related to back-reactions between solids and melt), and used to derive the metamorphic evolution of the studied samples. The P^T pseudosection modelling predicts that at least 15^20 vol.% ofmeltwasproducedat peakP^Tconditions through dehydrationmelting of both muscovite and biotite, and that melt production was mainly triggered by heating, with or without the combined effect ofdecompression.The preserved granulitic peak metamorphic assemblage, however, is consistent with a significant loss ofmost of this melt.TheP^Tevolution inferred forsamplesfrom different, strategically located, structural levelsoftheBarunGneiss isconsistentwiththeexpectationsofa‘channel flow’model, including: (1) the clockwise shape of the P^T paths; (2) the estimatedPat peakT(newdata:10^8 kbarat 8008C;model:13^7 kbar at 8008C); (3) the decreasing P structurally upward, which defines a ‘normal’ metamorphic sequence, in contrast to the inverted metamorphic sequence occurring in the lowermost Main Central Thrust Zone; (4) the nearly isothermal exhumation of the structurally lowest sample, reflecting the progressive exhumation of rocks that have been entrained in the deep, high-T region of the channel, versus the nearly isobaric heating of the structurally uppermost sample, reflecting the evolution of those rocks that flowed outwards with the underlying channel.