The formation of homogentisate in the biosynthesis of tocopherol and plastoquinone in spinach chloroplasts

Homogentisate is the precursor in the biosynthesis of -tocopherol and plastoquinone-9 in chloroplasts. It is formed of 4-hydroxyphenylpyruvate of the shikimate pathway by the 4-hydroxyphenylpyruvate dioxygenase. In experiments with spinach the dioxygenase was shown to be localized predominatedly in the chloroplasts. Envelope membranes exhibit the highest specific activity, however, because of the high stromal portion of chloroplasts, 60–80% of the total activity is housed in the stroma. The incorporation of 4-hydroxyphenylpyruvate into 2-methyl-6-phytylquinol as the first intermediate in the tocopherol synthesis by the two-step-reaction: 4-Hydroxyphenylpyruvate Homogentisate 2-Methyl-6-phytylquinol was demonstrated by using envelope membranes. Homogentisate originates directly from 4-hydroxyphenylpyruvate of the shikimate pathway. Additionally, a bypass exists in chloroplasts which forms 4-hydroxyphenylpyruvate from tyrosine by an L-amino-acid oxidase of the thylakoids and in peroxisomes by a transaminase reaction. Former results about the dioxygenase in peroxisomes were verified

'I am who I am'? Navigating norms and the importance of authenticity in lesbian and bisexual women's accounts of their appearance practices

This article explores how lesbian and bisexual women negotiate pressures to look like an authentic lesbian and an authentic individual in their accounts of their clothing and appearance practices. Thirty women responded to a 'paper-and-pen' qualitative survey about lesbian and bisexual women's dress and appearance. Two main themes were generated from the data: 'norms and conformity' and 'freedom and authenticity'. Conformity to appearance mandates raised questions about individual authenticity; the women negotiated this dilemma either by presenting their conformity as active and strategic, a means to an end (subverting normative assumptions of heterosexuality, being recognised by other non-heterosexual women) or as an almost unconscious expression of their inner dyke. For feminine and other non-conforming women, their lack of conformity raised questions about their authenticity as a non-heterosexual woman (and their feminist credentials), and some of these women negotiated this dilemma by presenting their femininity as a subversion of heteronormative assumptions by showing that any woman can be a lesbian. We conclude this article by highlighting the potential for over-reading sexuality in accounts of sexuality and appearance practices. © 2013 Copyright Taylor and Francis Group, LLC

Introducing lesbian, gay and bisexual appearance psychology

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