Sexuality and Body Image

Ryan Sallans discusses the relationship between body image and sexuality; Sallans breaks down sexuality into five main categories: sensuality, intimacy, sexualization, sexual health and reproduction and sexual identity. His talk looks at how the mass media idealizes the hourglass shape for women’s bodies, only 8 percent of women actually have that body type; GLBT Center; LGBTQ Center; Ryan Sallans; 171717ththth Annual LGBTIQQ Symposium; Connected CommunitiesConnected Communitie

Natively oxidized amino acid residues in the spinach cytochrome b\u3csub\u3e6\u3c/sub\u3e f complex

© 2018, Springer Science+Business Media B.V., part of Springer Nature. The cytochrome b6f complex of oxygenic photosynthesis produces substantial levels of reactive oxygen species (ROS). It has been observed that the ROS production rate by b6f is 10–20 fold higher than that observed for the analogous respiratory cytochrome bc1 complex. The types of ROS produced (O2•−, 1O2, and, possibly, H2O2) and the site(s) of ROS production within the b6f complex have been the subject of some debate. Proposed sources of ROS have included the heme bp, PQp•− (possible sources for O2•−), the Rieske iron–sulfur cluster (possible source of O2•− and/or 1O2), Chl a (possible source of 1O2), and heme cn (possible source of O2•− and/or H2O2). Our working hypothesis is that amino acid residues proximal to the ROS production sites will be more susceptible to oxidative modification than distant residues. In the current study, we have identified natively oxidized amino acid residues in the subunits of the spinach cytochrome b6f complex. The oxidized residues were identified by tandem mass spectrometry using the MassMatrix Program. Our results indicate that numerous residues, principally localized near p-side cofactors and Chl a, were oxidatively modified. We hypothesize that these sites are sources for ROS generation in the spinach cytochrome b6f complex

Identification of oxidized amino acid residues in the vicinity of the Mn \u3csub\u3e4\u3c/sub\u3eCaO \u3csub\u3e5\u3c/sub\u3e cluster of photosystem II: Implications for the identification of oxygen channels within the photosystem

As a light-driven water-plastoquinone oxidoreductase, Photosystem II produces molecular oxygen as an enzymatic product. Additionally, under a variety of stress conditions, reactive oxygen species are produced at or near the active site for oxygen evolution. In this study, Fourier-transform ion cyclotron resonance mass spectrometry was used to identify oxidized amino acid residues located in several core Photosystem II proteins (D1, D2, CP43, and CP47) isolated from spinach Photosystem II membranes. While the majority of these oxidized residues (81%) are located on the oxygenated solvent-exposed surface of the complex, several residues on the CP43 protein ( 354E, 355T, 356M, and 357R) which are in close proximity (\u3c15 \u3eÅ) to the Mn 4CaO 5 active site are also modified. These residues appear to be associated with putative oxygen/reactive oxygen species exit channel(s) in the photosystem. These results are discussed within the context of a number of computational studies which have identified putative oxygen channels within the photosystem. © 2012 American Chemical Society

Natively oxidized amino acid residues in the spinach PS I-LHC I supercomplex

© 2020, Springer Nature B.V. Reactive oxygen species (ROS) production is an unavoidable byproduct of electron transport under aerobic conditions. Photosystem II (PS II), the cytochrome b6/f complex and Photosystem I (PS I) are all demonstrated sources of ROS. It has been proposed that PS I produces substantial levels of a variety of ROS including O2.−, 1O2, H2O2 and, possibly, •OH; however, the site(s) of ROS production within PS I has been the subject of significant debate. We hypothesize that amino acid residues close to the sites of ROS generation will be more susceptible to oxidative modification than distant residues. In this study, we have identified oxidized amino acid residues in spinach PS I which was isolated from field-grown spinach. The modified residues were identified by high-resolution tandem mass spectrometry. As expected, many of the modified residues lie on the surface of the complex. However, a well-defined group of oxidized residues, both buried and surface-exposed, lead from the chl a’ of P700 to the surface of PS I. These residues (PsaB: 609F, 611E, 617M, 619W, 620L, and PsaF: 139L, 142A,143D) may identify a preferred route for ROS, probably 1O2, to egress the complex from the vicinity of P700. Additionally, two buried residues located in close proximity to A1B (PsaB:712H and 714S) were modified, which appears consistent with A1B being a source of O2.−. Surprisingly, no oxidatively modified residues were identified in close proximity to the 4Fe–FS clusters FX, FA or FB. These cofactors had been identified as principal targets for ROS damage in the photosystem. Finally, a large number of residues located in the hydrophobic cores of Lhca1–Lhca4 are oxidatively modified. These appear to be the result of 1O2 production by the distal antennae for the photosystem

Association of the 17-kDa extrinsic protein with photosystem II in higher plants

The structural association of the spinach 17-kDa extrinsic protein of photosystem II with other extrinsic and membrane-bound components of the photosystem was investigated by labeling the 17-kDa extrinsic protein with the amino-group-specific reagent N-hydroxysuccinimidobiotin both on intact photosystem II membranes or as a free protein in solution. After isolation of the biotinylated molecules, the modified 17-kDa proteins were allowed to rebind to photosystem II membranes which were depleted of the 17-kDa component. Differential binding of the protein biotinylated in solution compared to unmodified 17-kDa protein or 17-kDa protein modified on PSII membranes was observed. This indicated possible steric or ionic interference because of biotinylated lysyl residues present on the protein modified in solution. Biotinylated sites on the different modified 17-kDa proteins were identified by trypsin and Staphylococcus V8 protease digestion, followed by affinity chromatography enrichment of the biotinylated peptides and analysis of the peptide fragment mixture by nanospray liquid chromatography-tandem mass spectrometry. Four lysyl residues that were modified when the protein was biotinylated in solution were not biotinylated when the protein was modified on the PS II membrane (90K, 96K, 101K, and 102K). These residues appear to identify a protein domain involved in the interaction of the 17-kDa protein with the other components of the photosystem. © 2005 American Chemical Society

Radiolytic mapping of solvent-contact surfaces in photosystem II of higher plants: Experimental identification of putative water channels within the photosystem

Background: Substrate water must reach the buried Mn4O 5Ca cluster in Photosystem II. Results: OH produced by radiolysis modified buried amino acid residues. These were mapped onto the PS II crystal structure. Conclusion: Two groups of oxidized residues were identified which form putative pathways to the Mn4O5Ca cluster. Significance: Identification of water and oxygen channels is crucial for our understanding of Photosystem II function. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc

A Case Study in the Evolution of Digital Services for Science and Engineering Libraries

Building on experiences from earlier digital initiatives and partnerships, the University of Virginia has developed new services and forged new collaborations between traditional information technology and library units in support of changing approaches to science and engineering research and education. Over the past 4 years, the library has evolved through numerous service models, changes in institutional vision, and budgetary shortfalls and has emerged with a new understanding of where to invest resources and energy for coming challenges

Amino acid oxidation of the D1 and D2 proteins by oxygen radicals during photoinhibition of Photosystem II

The Photosystem II reaction center is vulnerable to photoinhibition. The D1 and D2 proteins, lying at the core of the photosystem, are susceptible to oxidative modification by reactive oxygen species that are formed by the photosystem during illumination. Using spin probes and EPR spectroscopy, we have determined that both O2 -and HO are involved in the photoinhibitory process. Using tandem mass spectroscopy, we have identified a number of oxidatively modified D1 and D2 residues. Our analysis indicates that these oxidative modifications are associated with formation of HO at both the Mn4O5Ca cluster and the nonheme iron. Additionally, O2 -appears to be formed by the reduction of O2 at either PheoD1 or QA. Early oxidation of D1:332H,which is coordinatedwith theMn1 of the Mn4O5Ca cluster, appears to initiate a cascade of oxidative events that lead to the oxidative modification of numerous residues in the C termini of the D1 and D2 proteins on the donor side of the photosystem. Oxidation of D2:244Y, which is a bicarbonate ligand for the nonheme iron, induces the propagation of oxidative reactions in residues of the D-de loop of the D2 protein on the electron acceptor side of the photosystem. Finally, D1: 130E and D2: 246Mare oxidatively modified by O2 -formed by the reduction of O2 either by PheoD1 -or QA -. The identification of specific amino acid residues oxidized by reactive oxygen species provides insights into the mechanism of damage to the D1 and D2 proteins under light stress