Comparative biochemical studies of carotenoids in sea-urchins—I

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Download Full-text

Ruthenium Red Staining of Human Hard Keratin Fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054005 ◽

1982 ◽

Vol 40 ◽

pp. 278-279

Author(s):

M. C. Buhrer ◽

R. A. Mathews

Keyword(s):

Human Hair ◽

Ruthenium Red ◽

Acid Mucopolysaccharides ◽

Biochemical Studies ◽

Keratin Fibers ◽

Ruthenium Red Staining ◽

Extracellular Materials

Ruthenium red has been used as a stain to demonstrate a variety of extracellular materials, especially acid mucopolysaccharides. It also reacts with certain intracellular and extracellular lipids. Since biochemical studies in our laboratory demonstrated the presence of a variety of monosaccharides in human hair ruthenium red staining procedures were adopted in order to evaluate the presence and morphological location of acid oligosaccharides in the keratinized aspect of hair.

Download Full-text

Effects of Hypophysectomy on the Fine Structure of Rat Liver Cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100060799 ◽

1967 ◽

Vol 25 ◽

pp. 156-157

Author(s):

Robert R. Cardell

Keyword(s):

Electron Microscopy ◽

Fine Structure ◽

Rat Liver ◽

Liver Cell ◽

Anterior Pituitary ◽

Liver Cells ◽

Biochemical Studies ◽

Liver Functions ◽

Rat Liver Cells ◽

And Control

Hypophysectomy of the rat renders this animal deficient in the hormones of the anterior pituitary gland, thus causing many primary and secondary hormonal effects on basic liver functions. Biochemical studies of these alterations in the rat liver cell are quite extensive; however, relatively few morphological observations on such cells have been recorded. Because the available biochemical information was derived mostly from disrupted and fractionated liver cells, it seemed desirable to examine the problem with the techniques of electron microscopy in order to see what changes are apparent in the intact liver cell after hypophysectomy. Accordingly, liver cells from rats which had been hypophysectomized 5-120 days before sacrifice were studied. Sham-operated rats served as controls and both hypophysectomized and control rats were fasted 15 hours before sacrifice.

Download Full-text

Fate of sperm membrane in fertilized ova

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146047 ◽

1993 ◽

Vol 51 ◽

pp. 40-41

Author(s):

Frank J. Longo

Keyword(s):

Electron Microscopy ◽

Electrical Activity ◽

Sea Urchins ◽

Morphological Changes ◽

Integrated System ◽

Electrophysiological Recording ◽

Experimental Conditions ◽

The Status ◽

Sperm Membrane ◽

Temporal And Spatial

Measurement of the egg's electrical activity, the fertilization potential or the activation current (in voltage clamped eggs), provides a means of detecting the earliest perceivable response of the egg to the fertilizing sperm. By using the electrical physiological record as a “real time” indicator of the instant of electrical continuity between the gametes, eggs can be inseminated with sperm at lower, more physiological densities, thereby assuring that only one sperm interacts with the egg. Integrating techniques of intracellular electrophysiological recording, video-imaging, and electron microscopy, we are able to identify the fertilizing sperm precisely and correlate the status of gamete organelles with the first indication (fertilization potential/activation current) of the egg's response to the attached sperm. Hence, this integrated system provides improved temporal and spatial resolution of morphological changes at the site of gamete interaction, under a variety of experimental conditions. Using these integrated techniques, we have investigated when sperm-egg plasma membrane fusion occurs in sea urchins with respect to the onset of the egg's change in electrical activity.

Download Full-text