R2R3-type MYB transcription factors (TFs) play important roles in transcriptional regulation of anthocyanins. The R2R3-type IbMYB1 is known to be a key regulator of anthocyanin biosynthesis in the storage roots of sweetpotato. We previously showed that transient expression of IbMYB1a led to anthocyanin pigmentation in tobacco leaves. In this article, we generated transgenic Arabidopsis plants expressing the IbMYB1a gene under the control of CaMV 35S promoter, and the sweetpotato SPO and SWPA2 promoters. Overexpression of IbMYBa in transgenic Arabidopsis produced strong anthocyanin pigmentation in seedlings and generated a deep purple color in leaves, stems and seeds. Reverse transcription-polymerase chain reaction analysis showed that IbMYB1a expression induced upregulation of several structural genes in the anthocyanin biosynthetic pathway, including 4CL, CHI, F3'H, DFR, AGT, AAT and GST. Furthermore, overexpression of IbMYB1a led to enhanced expression of the AtTT8 (bHLH) and PAP1/AtMYB75 genes. high-performance liquid chromatography analysis revealed that IbMYB1a expression led to the production of cyanidin as a major core molecule of anthocyanidins in Arabidopsis, as occurs in the purple leaves of sweetpotato (cv. Sinzami). This result shows that the IbMYB1a TF is sufficient to induce anthocyanin accumulation in seedlings, leaves, stems and seeds of Arabidopsis plants.
A new simplified procedure for identifying human plasmin was developed using a DTT copolymerized agarose stacking gel (ASG) system. Agarose (1 %) was used for the stacking gel because DTT inhibits the polymerization of acrylamide. Human plasmin showed the lowest activity at pH 9.0. There was a similar catalytically active pattern observed under acidic conditions (pH 3.0) to that observed under alkaline conditions (pH 10.0 or 11.0). Using the ASG system, the primary structure of the heavy chain could be established at pH 3.0. This protein was found to consist of three fragments, 45 kDa, 23 kDa, and 13 kDa. These results showed that the heavy chain has a similar structure to the autolysed plasmin (Wu et al., 1987b) but there is a different start amino acid sequence of the N-termini.
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