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During microspore embryogenesis, microspores are induced to develop into haploid embryos. In Brassica napus, microspore embryogenesis is induced by a heat shock (HS), which initially produces embryogenic structures with different cell wall architectures and compositions, and with different potentials to develop into embryos. The B. napus DH4079 and DH12075 genotypes have high and very low embryo yields, respectively. In DH12075, embryo yield is greatly increased by combining HS and the histone deacetylase (HDAC) inhibitor trichostatin A (TSA). However, we show that HS + TSA inhibits embryogenesis in the highly embryogenic DH4079 line. To ascertain why TSA has such different effects in these lines, we treated DH4079 and DH12075 microspore cultures with TSA and compared the cell wall structure and composition of the different embryogenic structures in both lines, specifically the in situ levels and distribution of callose, cellulose, arabinogalactan proteins and high and low methyl‐esterified pectin. For both lines, HS + TSA led to the formation of cell walls unfavorable for embryogenesis progression, with reduced levels of arabinogalactan proteins, reduced cell adhesion of inner walls and altered pectin composition. Thus, TSA effects on cell walls cannot explain their different embryogenic response to TSA. We also applied TSA to DH4079 cultures at different times and concentrations before HS application, with no negative effects on embryogenic induction. These results indicate that DH4079 microspores are hypersensitive to combined TSA and HS treatments, and open up new hypotheses about the causes of such hypersensitivity. [ABSTRACT FROM AUTHOR]

Addressing the need for curbing private motorization and car dependency while reducing inequalities associated with transport requires an in-depth understanding of the individual and collective practices, attitudes, and experiences of urban accessibility and mobility of populations across diverse socio-economic backgrounds. This paper builds on qualitative research methods and a framework of transitions to sustainable mobility to examine the links between travel needs, preferences, attitudes, and structural factors such as urban form, poverty, and informality at different scales. It proposes qualitative methods and evidence for accessibility-centred analysis to enrich policy and practice in cities across Sub-Saharan Africa (SSA), using Sierra Leone's capital, Freetown, as a case study. While the volume of literature on urban mobility, accessibility, and land-use in SSA is increasing, scholarship on cities in Western Africa remains limited. The study examines four neighborhoods with different levels of access and motorization. It interrogates participants' perceived accessibility, how they shape differentiated everyday mobility and land-use practices at the individual and collective level, and its implications for urban accessibility and sustainable mobility in the medium to long-term future. We found that perceived accessibility influences everyday mobility and land-use practices and the attitudes of individuals in diverse communities toward sustainable mobility by driving them to trade off immediate needs with long-term risks and exposures, imaginaries of motorized futures, as well as collectively transform the functional and physical configurations of the built environment to address their most critical needs in the absence of suitable top-down transport and land-use interventions. [ABSTRACT FROM AUTHOR]

This paper confronts the current policy landscape and lived experiences of walking in African cities through the lens of policies, plans, institutional, and residents’ narratives. The paper builds on qualitative evidence drawn from content analysis and semi-structured interviews with local-level stakeholders across policy sectors concerned directly or indirectly with walking and walkability in the city. Perspectives from local government institutions are first reviewed to ascertain considerations for accessibility, safety, and pleasurability dimensions of walking and, second, contrasted with the lived walking experiences of residents of low-income settlements in Accra. Results indicate limited attention to pleasurability dimensions in both policy and municipal plans and significant incongruities with residents’ lived realities of walking. This parallel between the frameworks and plans underpinning the construction of the walking environment and the lived experiences of those affected by such decisions seeks to nuance debates about policy-reality (dis)junctures in African urbanism. [ABSTRACT FROM AUTHOR]