Judith A. Murphy

DOPA decarboxylase activity in the nervous system and the ctenidium of the freshwater clam, Musculium (Sphaerium) transversum.

Dopa decarboxylase was measured in ganglia, connectives, branchial nerve and ctenidium of the clam, Musculium transversum. DOPA decarboxylase inhibitors (STH, HMD, and alpha-methyl-DOPA) reduced the enzymatic activity in all extracts. Ligation and extirpation of the visceral ganglion and branchial nerve significantly decreased the enzymatic activity in the ctenidium. Scanning electron microscopic observations showed numerous degenerative changes in nerve cells with progressive destruction of axons within the branchial nerve. In conclusion, it appears that lateral ctenidial cilia are dependent upon the decarboxylase activity of the visceral ganglion and branchial nerve.

Ultrastructure of Diplodia maydis grown on selected synthetic media

AbstractOf all the fixatives studied, glutaraldehyde followed by osmium was considered best. Fixation temperatures did not result in ultrastructural differences. Holdover for short periods (up to 7 days) in 70% alcohol and long periods (3 months) in glutaraldehyde did not result in ultrastructural differences from those processed without a hold-over period. Uranyl acetate increased contrast, as expected. Epon was selected over Epon-Araldite (more viscous) and Spurrs resin (less contrast). Generally, growth conditions did not alter gross hyphal morphology, although cytological changes were noted. Diplodia maydis is morphologically similar to ascomycetous fungi. It contained typical organelles as found in other fungi, e.g. cell wall, septa, Woronin bodies, nuclei, mitochondria, endoplasmic reticulum, lomasomes, plasma membranes, cytosomes, vacuoles, storage materials (lipids, carbohydrates and intracellular and extracellular electrondense substances), thickened mycelial strands, and intrahyphal hyphae. Bead-like structures and thickened nodes as observed by SEM were accounted for by structures observed by TEM. Mitochondria were dramatically elongated, and in one case, branched. Hyphae were organized in three zones: apical, subapical, and vacuolated. Apical vesicles were thought to account for cell extension. Evidence was presented that Woronin bodies originated from microbodies. It was suggested that the Golgi apparatus consists of isolated single cisternae. Free ribo- or polysomes (without ER) were suggested as the site of the majority of protein synthesis. Continuities and configurations of plasma and outer nuclear and mitochondrial membranes, ER, cytosomes, vacuoles and storage materials suggested that a system similar to Morre et als endomembrane system is in operation in D. maydis to account for component flow and differentiation.

The effect of STH and 6-OH-dopa on the SEM of the branchial nerve and visceral ganglion of the bivalve Elliptio complanata as it relates to ciliary activity.

Abstract 1. Lateral ciliary activity was studied in isolated gill-branchial nerve-visceral ganglion preparations in the mussel Elliptio complanata . 2. Intramuscular injection of STH, a decarboxylase inhibitor, causes the rate of beating of lateral cilia to decrease in response to branchial nerve stimulation. Recovery occurs about 10 days post-injection 3. STH also causes a simultaneous decrease in the size and number of varicosities in the branchial nerve as observed by scanning electron microscopy (SEM). 4. Intramuscular injection of 6-OH-DOPA causes the rate of beating of lateral cilia to decrease in response to branchial nerve stimulation. No recovery was observed. 5. 6-OH-DOPA also causes extensive destruction of the branchial nerve and visceral ganglion as viewed by SEM. 6. Therefore it appears that ciliary activity is dependent on the visceral ganglion and branchial nerve.