University of Windsor

About: University of Windsor is a education organization based out in Windsor, Ontario, Canada. It is known for research contribution in the topics: Population & Argumentation theory. The organization has 10654 authors who have published 22307 publications receiving 435906 citations. The organization is also known as: UWindsor & Assumption University of Windsor.

δ15N and δ13C diet-tissue discrimination factors for large sharks under semi-controlled conditions

Abstract: Stable isotopes ( δ 15 N and δ 13 C) are being widely applied in ecological research but there has been a call for ecologists to determine species- and tissue-specific diet discrimination factors (∆ 13 C and ∆ 15 N) for their study animals. For large sharks stable isotopes may provide an important tool to elucidate aspects of their ecological roles in marine systems, but laboratory based controlled feeding experiments are impractical. By utilizing commercial aquaria, we estimated ∆ 15 N and ∆ 13 C of muscle, liver, vertebral cartilage and a number of organs of three large sand tiger ( Carcharias taurus ) and one large lemon shark ( Negaprion brevirostris ) under a controlled feeding regime. For all sharks mean ± SD for ∆ 15 N and ∆ 13 C in lipid extracted muscle using lipid extracted prey data were 2.29‰ ± 0.22 and 0.90‰ ± 0.33, respectively. The use of non-lipid extracted muscle and prey resulted in very similar ∆ 15 N and ∆ 13 C values but mixing of lipid and non-lipid extracted data produced variable estimates. Values of ∆ 15 N and ∆ 13 C in lipid extracted liver and prey were 1.50‰ ± 0.54 and 0.22‰ ± 1.18, respectively. Non-lipid extracted diet discrimination factors in liver were highly influenced by lipid content and studies that examine stable isotopes in shark liver, and likely any high lipid tissue, should strive to remove lipid effects through standardising C:N ratios, prior to isotope analysis. Mean vertebral cartilage ∆ 15 N and ∆ 13 C values were 1.45‰ ± 0.61 and 3.75‰ ± 0.44, respectively. Organ ∆ 15 N and ∆ 13 C values were more variable among individual sharks but heart tissue was consistently enriched by ~ 1–2.5‰. Minimal variability in muscle and liver δ 15 N and δ 13 C sampled at different intervals along the length of individual sharks and between liver lobes suggests that stable isotope values are consistent within tissues of individual animals. To our knowledge, these are the first reported diet–tissue discrimination factors for large sharks under semi-controlled conditions, and are lower than those reported for teleost fish.

Mechanism of transfer of NO from extracellular S-nitrosothiols into the cytosol by cell-surface protein disulfide isomerase.

Abstract: N-dansylhomocysteine (DnsHCys) is quenched on S-nitrosation. The product of this reaction, N-dansyl-S-nitrosohomocysteine, is a sensitive, direct fluorogenic substrate for the denitrosation activity of protein disulfide isomerase (PDI) with an apparent K(M) of 2 microM. S-nitroso-BSA (BSA-NO) competitively inhibited this reaction with an apparent K(I) of 1 microM. The oxidized form of DnsHCys, N,N-didansylhomocystine, rapidly accumulated in cells and was reduced to DnsHCys. The fluorescence of DnsHCys-preloaded human umbilical endothelial cells and hamster lung fibroblasts were monitored as a function of extracellular BSA-NO concentration via dynamic fluorescence microscopy. The observed quenching of the DnsHCys fluorescence was an indirect measure of cell surface PDI (csPDI) catalyzed denitrosation of extracellular S-nitrosothiols as decrease or increase in the csPDI levels in HT1080 fibrosarcoma cells correlated with the rate of quenching and the PDI inhibitors, 5,5'-dithio-bis-3-nitrobenzoate and 4-(N-(S-glutathionylacetyl) amino)phenylarsenoxide inhibited quenching. The apparent K(M) values for denitrosation of BSA-NO by csPDI ranged from 12 microM to 30 microM. Depletion of membrane N(2)O(3) with the lipophylic antioxidant, vitamin E, inhibited csPDI-mediated quenching rates of DnsHCys fluorescence by approximately 70%. The K(M) for BSA-NO increased by approximately 3-fold and V(max) decreased by approximately 4-fold. These findings suggest that csPDI catalyzed NO released from extracellular S-nitrosothiols accumulates in the membrane where it reacts with O2 to produce N(2)O(3). Intracellular thiols may then be nitrosated by N2O3 at the membrane-cytosol interface.

Evaluating and optimizing power consumption of anti-collision protocols for applications in RFID systems

Abstract: For low-cost RFID systems, the design of passive tags is a key issue in anti-collision protocols where lower power consumption allows a longer working distance between tags and the reader. In this paper, we look at anti-collision protocols in tags' processing for their power optimization. We propose a new criterion, which takes into account both energy consumption and time complexity, to evaluate anti-collision protocols. An improved protocol is also presented for power savings.