THE ROLE OF ZINC IN THE GROWTH OF PLANT TISSUE CULTURES

Klein , Richard M., Emerita M. Caputo , and Barbara A. Witterholt . (New York Bot. Gard., N. Y., N. Y.) The role of zinc in the growth of plant tissue cultures. Amer, Jour. Bot. 49(4): 323–327. Illus. 1962.—Zinc-sufficient and zinc-deficient auxin-auxotrophic callus and auxin-prototrophic crown-gall cultures of Parthenocissus tricuspidatus were examined for their growth capacity and ability to synthesize tryptophan. Growth capacity decreased rapidly when zinc ion was withheld and tryptophan synthetase activity in vitro was reduced. Growth of –Zn crown-gall tissues was stimulated by either auxin or tryptophan and growth of –Zn callus cultures was stimulated by tryptophan.     

PHASE CONTRAST OBSERVATIONS OF THE ENDOPLASMIC RETICULUM IN LIVING TISSUE CULTURES

Cells from three human sources (two malignant and one fetal) were observed through phase contrast microscopy to contain unusual cytoplasmic images. These were photographed and are discussed as representing the endoplasmic reticulum in the living cell.     

表皮生长因子受体在正常大鼠眼组织中的表达

采用免疫组织化学方法观察了表皮生长因子受体在正常大鼠眼组织的表达。结果发现：角膜上皮的深层细胞和角膜缘上皮细胞、部分结膜上皮细胞和结膜下结缔组织内成纤维细胞均强烈表达表皮生长因子受体。结果显示：表皮生长因子受体阳性细胞主要分布于眼表层组织。这些细胞不仅是眼组织损伤后修复、而且是多种手术能否成功和某些疾病形成中起重要作用的细胞     

小鼠脑中32种元素含量正常参考值的测定

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PLASMODESMATA AND AN ASSOCIATED CELL WALL COMPONENT IN BARLEY ALEURONE TISSUE

A unique cell wall component has been observed in the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya). This wall component has been shown to be localized adjacent to the plasmalemma. Unlike the surrounding cell wall matrix it is resistant to “Onozuka” cellulase and remains intact during gibberellic acid-stimulated hydrolase release. After treatment of the tissue with gibberellic acid followed by digestion with “Onozuka” cellulase this resistant wall component can be isolated free of protoplast. Study of its surface features revealed the presence of numerous tubular extensions, 120 nm wide, connecting adjacent resistant walls. These tubes resembled light microscope images of plasmodesmata in size and appearance. E.M. sections of resistant walls showed the presence of unit membrane lining the inner surface of the wall tubes. It was concluded that the resistant wall constitutes a modified wall layer that is secreted uniformly across all plasmalemma surfaces, including those in the wall (plasmodesmata). The presence of wall tubes surrounding plasmodesmata enhances the apparent size of the plasmodesmata in the light microscope. This may account for previous inconsistencies in the literature between light and electron microscope determinations of plasmodesmata diameters.