'Elaioplasts' identified as lipotubuloids in Althaea rosea, Funkia sieboldiana and Vanilla planifolia contain lipid bodies connected with microtubules

"Elaioplasts" observed in <em>Vanilla planifolia</em>, <em>Funkia Sieboldiana</em> and <em>Althaea rosea </em>exhibit all the features characteristic of lipotubuloids earlier described in <em>Ornithogalum umbellatum</em>. They are cytoplasmic domains containing aggregates of lipid bodies connected with microtubules. The immunogold technique confirmed the presence of tubulin in this domain. These structures do not have their own membranes but they are surrounded by a tonoplast at the side of a vacuole since they invaginate into it. In cytoplasm of this domain among lipid bodies there are numerous ribosomes, ER cisternae and vesicles as well as few mitochondria, Golgi structures and microbodies while at older developmental stages there are also autolytic vacuoles. The fact that they are so similar to <em>O. umbellatum</em> lipotubuloids suggest that "elaioplasts" of <em>V. planifolia</em>, <em>F. Sieboldiana </em>and <em>A. rosea </em>can also be named lipotubuloids.

Evaluation of the Sensitivity of the Terminal Deoxynucleotidyl Transferase–Immunogold Technique on Balbani Ring Genes

Recently, we developed the terminal deoxynucleotidyl transferase (TdT)–immunogold technique for in situ detection of DNA molecules. In this study the potential value and the limitations of the method were evaluated using the giant polytene chromosomes from Chironomus tentans salivary glands. Emphasis was put on the Balbiani rings (BRs), specialized chromosomal sites with exceptionally intense synthesis of large mRNA molecules. Immunolabeling was recorded not only over the bands and interbands of the polytene chromosomes but also over the BR structures. In the BRs, gold particles were present over segments of active transcription units, each with a central chromatin axis and a number of growing RNP products attached to the axis. One third of the transversely sectioned transcription units showed labeling in the central parts, i.e., where the unfolded chromatin axis is located, whereas the growing RNP fibers remained unlabeled. The absence of labeling of the RNP fibers is not likely to be due to lack of accessibility, because anti-RNA antibodies readily decorated the RNP fibers. The nuclear sap and cytoplasm displayed no significant label. These results clearly indicate that the TdT–immunogold technique is specific for DNA and detects not only DNA in compacted chromatin but also fully extended DNA. Its ability to efficiently label a single DNA molecule demonstrates the method's very high sensitivity.