Non-invasive magnetic resonance imaging of oils in Botryococcus braunii green algae: Chemical shift selective and diffusion-weighted imaging

Abstract

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.

Light Acclimation of the Colonial Green Alga Botryococcus braunii Strain Showa

“…Diffusion of nutrients and light attenuation can limit the viable region within colonies (Ploug et al, 1999) and biofilms (Stewart, 2003). Moreover, diffusion was recently shown to be low in the oil-rich parts of the colony (van Schadewijk et al, 2018), making this scenario very plausible.…”

Probing microstructural changes in muscles of leptin-deficient zebrafish by non-invasive ex-vivo magnetic resonance microimaging

“…No significant difference was seen in T 2 quantification using single vs four slice acquisition (S1 Table in S1 File). Diffusion measurements were performed at 17.6 T using a spin-echo pulse sequence with a pair of mono-polar diffusion-sensitizing gradients [34]. Gradient orientations were evenly distributed in six isotropic directions.…”

Prospects and Challenges for the Spatial Quantification of the Diffusion of Fluids Containing 1H in the Pore System of Rock Cores

“…The emerging popularity of diffusion-based NMR imaging techniques in geosciences and related branches is a promising trend. Although unrelated to rocks or fossilized material, the paper of van Schadewijk et al (2018) can be mentioned as an example here. The authors employed DWI with six, isotropically distributed gradient directions to realize an in-vivo study of green algae, known to have the capability of producing oils in their lipid bodies.…”