Increasing cell biomass in Saccharomyces cerevisiae increases recombinant protein yield:the use of a respiratory strain as a microbial cell factory

BACKGROUND: Recombinant protein production is universally employed as a solution to obtain the milligram to gram quantities of a given protein required for applications as diverse as structural genomics and biopharmaceutical manufacture. Yeast is a well-established recombinant host cell for these purposes. In this study we wanted to investigate whether our respiratory Saccharomyces cerevisiae strain, TM6*, could be used to enhance the productivity of recombinant proteins over that obtained from corresponding wild type, respiro-fermentative strains when cultured under the same laboratory conditions. RESULTS: Here we demonstrate at least a doubling in productivity over wild-type strains for three recombinant membrane proteins and one recombinant soluble protein produced in TM6* cells. In all cases, this was attributed to the improved biomass properties of the strain. The yield profile across the growth curve was also more stable than in a wild-type strain, and was not further improved by lowering culture temperatures. This has the added benefit that improved yields can be attained rapidly at the yeast's optimal growth conditions. Importantly, improved productivity could not be reproduced in wild-type strains by culturing them under glucose fed-batch conditions: despite having achieved very similar biomass yields to those achieved by TM6* cultures, the total volumetric yields were not concomitantly increased. Furthermore, the productivity of TM6* was unaffected by growing cultures in the presence of ethanol. These findings support the unique properties of TM6* as a microbial cell factory. CONCLUSIONS: The accumulation of biomass in yeast cell factories is not necessarily correlated with a proportional increase in the functional yield of the recombinant protein being produced. The respiratory S. cerevisiae strain reported here is therefore a useful addition to the matrix of production hosts currently available as its improved biomass properties do lead to increased volumetric yields without the need to resort to complex control or cultivation schemes. This is anticipated to be of particular value in the production of challenging targets such as membrane proteins.

Violence against women in Ethiopia

Investigating the experience of violence against women and exploring women's coping strategies is a crucial component of re-tailoring the provision of services for victims/survivors. This article explores violence against women in the context of culture, theory of fear of violence and literature on spaces perceived to be 'safe' or 'dangerous' by women victims/survivors of violence in Ethiopia. To collect the relevant data, we conducted 14 semi-structured interviews with Ethiopian women who are victims/survivors of violence and three interviews with gender experts in Ethiopia. Our group of women suffer in 'silence' and confide only in friends and relatives. They did not resort to institutional support due to lack of awareness and general societal disapproval of such measures. This contrasts with claims by experts that the needs of these women are addressed using an institutional approach. Culture, migration status and lack of negotiating power in places of work are key factors when considering violence. The majority of the respondents in this study occupy both public and private spaces such as bars and homes and have experienced violence in those spaces. The social relations and subsequent offences they endured do not make spaces such as these safe. Education of both sexes, creation of awareness, sustainable resource allocation to support victims/survivors, ratification of the Maputo protocol and effective law enforcement institutions are some of the practical strategies we propose to mitigate the incidence of violence in Ethiopia. © 2010 Taylor & Francis.

Explaining the off-the-books enterprise culture of Ukraine:reluctant or willing entrepreneurship?

In recent years, there has been a growing realisation that beyond the realm of legitimate entrepreneurship is a large, hidden enterprise culture composed of entrepreneurs conducting some or all of their trade off-the-books. Until now, however, few have evaluated how many entrepreneurs start-up their ventures trading off-the-books and why they do so. Reporting face-to-face interviews conducted in Ukraine during 2005-2006 with 331 entrepreneurs, the finding is not only that the vast majority (90%) operate partially or wholly off-the-books, but also that they are not all driven by necessity, as a last resort and as a survival strategy into entrepreneurship. Revealing how many are willing rather than reluctant entrepreneurs; and that even those who were initially reluctant and ventured into it out of necessity, became more willing entrepreneurs over time as their business became established - the paper concludes by discussing the implications of these findings for both further research and public policy. © 2010 Wiley Periodicals, Inc.