Figure 7.

Exogenous [³H] rhamnogalacturonan-II (RG-II) fails to dimerise or integrate into walls in cultured Rosa cells. (a), (b) Monomeric [³H]RG-II (3.9 μm) was fed to B-starved 4-day-old Rosa cultures at the same time as 1.2 mm H₃BO₃. Samples of medium were electrophoresed: (a) fluorograph; (b) relevant bands scintillation counted. (c) In a separate experiment, 8.5 nm [³H]RG-II was fed to B-sufficient and B-deficient Rosa cultures, with or without 3.3 μm H₃BO₃ supplementation. At intervals, samples of medium were assayed for total remaining soluble ³H (graph); at 24 h, additional samples were assayed for volatile ³H (inset Table; indicating any ³H₂O formed by catabolism).