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Saffron (Crocus sativus L. Iridaceae) chromoplasts and other plastids were studied by electron microscope to determine their structure, origin and pigment localization. Plastids from pistils of floral buds and flowers at anthesis, dried and decoloured stigmas, and green and senescent leaves were examined. Results indicated that mature saffron chromoplasts occur in the red parts of stigmas and have a reticulo-tubular structure. They contain a reticulum of tubules and plastoglobules. Tubules formed dilated vesicles mainly while plastoglobules appeared numerous and scattered on the whole chromoplast. Chromoplasts appeared in red stigma of very young floral buds. They originated from amyloplasts, the only plastids occurring in the colourless basal portion of style, as well as in the parenchyma of ovary and corm. Transition forms of plastid as amylo-chromoplast, occur in the yellow parts of stigma and style. Senescent leaves did not show plastids with structure similar to the chromoplast of red stigma. Red pigmented and scented stigmas might cooperate in saffron reproduction by attracting pollinator. [ABSTRACT FROM AUTHOR]

Electron spectroscopy imaging (ESI) and electron energy loss spectroscopy (EELS) provide an opportunity to investigate the presence of different trace elements directly in the structure of fixed tissues. We evaluated the usefulness of such techniques in detecting the sub-cellular localization and relative content of manganese in the mitochondria of cells in the brain of normal rats. ESI provided a granular appearance to manganese ions aggregated at any site summed through the thickness of ultra-thin sections. EELS confirmed the presence of manganese in the organelles shown by ESI. To demonstrate the specificity of signals for manganese, a comparative study was also performed. Electron-spectroscopy analysis of manganese, iron and fluorine in the same mitochondria demonstrated the presence of strong and specific signals for manganese, but the absence of detectable iron, or of fluorine, which was expected to be normally absent. However, iron and manganese were both detected in myelin sheaths by ESI and the spectral analysis afforded by EELS revealed distinct peaks for manganese and iron in the same samples. The manganese concentration in mitochondria as measured by the relative optical density on photomicrographs was highly variable probably due to variability in organelle characteristics and subtle differences in section thickness. These results show that ESI and EELS are sensitive and valuable techniques to detect bound manganese within sub-cellular structures. [ABSTRACT FROM AUTHOR]

While studying the reproductive biology of Saffron (Crocus sativus L.) grown in the Botanical Gardens of the University of L'Aquila (Italy) (Grilli Caiola et al. 1982) it was found that many cells of the ovary, style and stigma contained particles similar to those found by Russo et al. (1979) in the leaf and root cells of the same Saffron species and identified as latent Bean yellow mosaic virus. Because Saffron cultivation in the Region Abruzzo (Italy) is economically important (Tammaro and De Francesco 1978) it was thought useful to draw attention to the possibility that besides other diseases also viruses could be the cause of reduced production of that crop. [ABSTRACT FROM AUTHOR]

Immunogold labeling and transmission electron microscopy were used to localize iron-superoxide dismutase (Fe-SOD) in the different cells of nitrogen-fixing cyanobacterial symbiont present within different leaf cavity groups of Azolla filiculoides Lam. As evidenced by Western blotting and immunoprecipitation, Fe-SOD antibody from Anabaena cylindrica recognized Fe-SOD in extracts of the cyanobiont and showed the same electrophoretic mobility and pattern as purified A. cylindrica Fe-SOD. In vegetative cells of the cyanobiont, Fe-SOD was mainly localized in the thylakoidal membranes and in the outer membrane. The labeling pattern was similar in vegetative cells of the various groups of leaf cavities examined except at the apex where a lower gold particle density was seen. In heterocysts of the leaf cavity groups containing high nitrogenase activity, Fe-SOD labeling was most pronounced and more intense than in vegetative cells. The Fe-SOD label was preferentially located throughout the heterocyst cytoplasm and in the honeycomb regions. In accordance with the decline in nitrogenase activity, the Fe-SOD gold particle density decreased significantly in heterocysts of basal leaf cavity group. The presence of Fe-SOD in regions of high nitrogenase protein levels, and the fact that the pattern of Fe-SOD label parallels that of nitrogenase activity support a role of Fe-SOD in the protection of nitrogenase against superoxide radicals. [ABSTRACT FROM AUTHOR]