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Sound velocities in pure water at various temperatures were measured. A PZT transducer sends a 2-MHz pulse towards a target stationed at an accurately known distance of 120 mm away. The transit time between the forward pulse and the reflected pulse was measured precisely with statistical averaging and a reference timebase derived from the NRC cesium frequency standard. The transducer-target probe and liquid chamber was immersed in a temperature controlled bath that was under the control of a computer. Measurements were repeated with known concentrations of alcohol and distilled water. Uncertainties of the measurements will be discussed. The authors would like to thank Lu-Jie of the Tongji University for his contribution to the construction of the measurement circuits. [ABSTRACT FROM AUTHOR]

Arabidopsis thaliana is the first model plant, the genome of which has been sequenced. In general, intensive studies on this model plant over the past nearly 30 years have led to many new revolutionary understandings in every single aspect of plant biology. Here, we review the current understanding of anthocyanin biosynthesis in this model plant. Although the investigation of anthocyanin structures in this model plant was not performed until 2002, numerous studies over the past three decades have been conducted to understand the biosynthesis of anthocyanins. To date, it appears that all pathway genes of anthocyanins have been molecularly, genetically and biochemically characterized in this plant. These fundamental accomplishments have made Arabidopsis an ideal model to understand the regulatory mechanisms of anthocyanin pathway. Several studies have revealed that the biosynthesis of anthocyanins is controlled by WD40-bHLH-MYB (WBM) transcription factor complexes under lighting conditions. However, how different regulatory complexes coordinately and specifically regulate the pathway genes of anthocyanins remains unclear. In this review, we discuss current progresses and findings including structural diversity, regulatory properties and metabolic engineering of anthocyanins in Arabidopsis thaliana.

Plants express genes that encode enzymes that catalyse reactions to form plant secondary metabolites in specific cell types. However, the mechanisms of how plants decide their cellular metabolic fate and how cells diversify and specialise their specific secondary metabolites remains largely unknown. Additionally, whether and how an established metabolic program impacts genome-wide reprogramming of plant gene expression is unclear. We recently isolated PAP1-programmed anthocyanin-producing (red) and -free (white) cells from Arabidopsis thaliana; our previous studies have indicated that the PAP1 expression level is similar between these two different cell types. Transcriptional analysis showed that the red cells contain the TTG1-GL3/TT8-PAP1 regulatory complex, which controls anthocyanin biosynthesis; in contrast, the white cells and the wild-type cells lack this entire complex. These data indicate that different regulatory programming underlies the different metabolic states of these cells. In addition, our previous transcriptomic comparison indicated that there is a clear difference in the gene expression profiles of the red and wild-type cells, which is probably a consequence of cell-specific reprogramming. Based on these observations, in this report we discuss the potential mechanisms that underlie the programming and reprogramming of gene expression involved in anthocyanin biosynthesis.