Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands.
Biophysics of Photosynthesis, Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
PLoS One. 2018 Aug 30;13(8):e0203217. doi: 10.1371/journal.pone.0203217. eCollection 2018.
Botryococcus braunii is an oleaginous green algae with the distinctive property of accumulating high quantities of hydrocarbons per dry weight in its colonies. Large variation in colony structure exists, yet its implications and influence of oil distribution and diffusion dynamics are not known and could not be answered due to lack of suitable in vivo methods. This publication seeks to further the understanding on oil dynamics, by investigating naturally relevant large (700-1500μm) and extra-large (1500-2500μm) sized colonies of Botryococcus braunii (race B, strain Showa) in vivo, using a comprehensive approach of chemical shift selective imaging, chemical shift imaging and spin echo diffusion measurements at high magnetic field (17.6T). Hydrocarbon distribution in large colonies was found to be localised in two concentric oil layers with different thickness and concentration. Extra-large colonies were highly unstructured and oil was spread throughout colonies, but with large local variations. Interestingly, fluid channels were observed in extra-large colonies. Diffusion-weighted MRI revealed a strong correlation between colony heterogeneity, oil distribution, and diffusion dynamics in different parts of Botryococcus colonies. Differences between large and extra-large colonies were characterised by using T2 weighted MRI along with relaxation measurements. Our result, therefore, provides first non-invasive MRI means to obtain spatial information on oil distribution and diffusion dynamics in Botryococcus braunii colonies.
布氏藻是一种产油的绿色藻类，其特征是在其群体中每干重积累大量碳氢化合物。群体结构存在很大的差异，但由于缺乏合适的体内方法，其对油分布和扩散动力学的影响和影响尚不清楚，也无法回答。本出版物旨在通过使用高磁场（17.6T）下的化学位移选择成像、化学位移成像和自旋回波扩散测量等综合方法，对体内天然相关的大型（700-1500μm）和特大型（1500-2500μm）布氏藻（B 种，Showa 株）群体进行研究，进一步了解油的动态，从而寻求对油动态的理解。结果表明，大型群体中的碳氢化合物分布局限于两个具有不同厚度和浓度的同心油层中。特大群体结构极不规则，油在整个群体中扩散，但局部变化很大。有趣的是，在特大群体中观察到了液流通道。扩散加权 MRI 显示，在布氏藻群体的不同部位，异质性、油分布和扩散动力学之间存在很强的相关性。利用 T2 加权 MRI 以及弛豫测量对大群体和特大群体之间的差异进行了表征。因此，我们的结果首次提供了非侵入性 MRI 手段，可获得布氏藻群体中油分布和扩散动力学的空间信息。
