Department of Biochemistry, University of Florida, College of Medicine, Gainesville, Florida, USA.
Planta. 1970 Sep;94(3):175-83. doi: 10.1007/BF00386127.
[1-(14)C]-L-arabinose was supplied to maize roots over a range of concentrations extending from 0.1 M to 0.04 mM. In each case, only xylose and arabinose units in the cell wall polysaccharides became labelled. However, although uptake increased with concentration, the conversion of L-arabinose to these cell wall units was not greatly influenced by raising the external sugar concentration, and there was no marked accumulation of UDP-pentose under any of the experimental conditions tested. Furthermore, specific activity of the arabinose isolated from the cell wall hydrolysates was always higher than that of the xylose. Because the labelling was so specific, patterns of pentose deposition could be followed by preparing autoradiographs of sections from roots fed with (14)C-L-arabinose. In the pith and cortex, which are typically parenchymatous tissues, the maximum rate of incorporation was observed in cell walls at around 2 mm from the cap-stele junction. These cells had just reached their full width and were about to undergo a phase of rapid elongation. Results are in essential aggrement with those obtained earlier with D-glucuronate in similar experiments.
[1-(14)C]-L-阿拉伯糖被供应给玉米根，浓度范围从 0.1 M 到 0.04 mM。在每种情况下，只有细胞壁多糖中的木糖和阿拉伯糖单位被标记。然而，尽管吸收随着浓度的增加而增加，但细胞壁单位的 L-阿拉伯糖转化率并没有因提高外部糖浓度而受到很大影响，在测试的任何实验条件下，UDP-戊糖都没有明显积累。此外，从细胞壁水解产物中分离出的阿拉伯糖的比活度始终高于木糖。由于标记非常特异，可以通过准备用 (14)C-L-阿拉伯糖喂养的根的切片的放射自显影来跟踪戊糖的沉积模式。在髓和皮层中，这些组织通常是薄壁组织，在距帽-茎交界处约 2 毫米的细胞壁中观察到最大的掺入速率。这些细胞刚刚达到它们的全宽，并且即将经历快速伸长的阶段。结果与早些时候在类似实验中用 D-葡萄糖醛酸获得的结果基本一致。
