Thesis (M.S.)--University of Delaware, 2006. / Principal faculty advisor: John F. Wehmiller, Dept. of Geological Sciences. Includes bibliographical references.

Thesis (M.Sc. (Zoology & Entomology)) - Rhodes University, 2007.

Thesis (Ph. D.)--University of Chicago, 1908. / "A Private edition distributed by the University of Chicago Libraries." "Reprinted from National academy of sciences memoirs, Vol. XII, Part 2, 1915." Includes bibliographical references (p. 87-92). Also available on the Internet.

Thesis (M.S.)--Ohio State University, 1974. / Includes bibliographical references (leaves 50-55). Available online via OhioLINK's ETD Center

An outline of our present knowledge concerning the occurrence, distribution and possible function of monoamines in the animal kingdom. The purpose of the present study was to investigate the localisation of monoamines in gastropod molluscs so as to gain insight into their functional significance.

The columellar muscle of both limpets and coiled shell gastropods is of the paramyosin smooth type. Collagen forms an integral part of the musculature constituting about 35% of the tissue. In limpets, muscle organisation is typical of a muscular hydrostat. Tightly packed blocks of muscle, dense arrays of cross-linked collagen, large muscle cells (9 µm diameter) and thick filaments (70 nm diameter, 30 µm long) produce a tough, relatively rigid but powerful muscle. In coiled shell gastropods, muscle organisation is intermediate between a muscular and a fluid hydrostat. Finer muscle cells (6 µm diameter), thick filaments (60 nm diameter) and a loose intercellular network of collagen interspersed with fluid vesicles are features of a more pliable and extensible muscle. In addition, ultrastructural differences, such as larger numbers of mitochondria and sarcolemmal invaginations distinguish the tarsal from the columellar muscle in both limpets and coiled shell gastropods. About 25% of muscle cells in most species examined, contain a novel arrangement of thin filaments with periodic electron-dense regions. These are similar in appearance to intrafusal cells and stress-fibres of non-muscle cells. Structural analysis of isolated filaments, optical diffraction and SDS gel electrophoresis confirm the, large dimensions and the paramyosin nature of the thick filaments. Microdensitometry of the gel proteins confirms the high proportion of collagen present. No significant differences in muscle ultrastructure were found between limpets from different tidal heights. Muscle attachment areas are shown to be species-specific and positively correlated to tenacity and wave exposure. The muscle attachment mechanism is similar to that described for other molluscs. It consists of a special epithelial layer and a mucous-like material at the muscle-shell interface that possibly has an adhesive function. Although the ultrastructure of Patella is very similar to that of the anterior byssus retractor of Mytilus, its mechanical behaviour is not. The muscle has a narrow working range where maximum tensions and "catch-like" contractions develop. This narrow length range is co-incident with the in situ length at which clamping occurs. It is suggested that the large component of collagen has an important influence over the mechanical behaviour of the muscle during clamping, by cross-linking in a manner similar to that described for some echinoderm connective tissues.

Anaerobic metabolism in cephalopod muscle and in bivalve adductor muscle depends on the coupling of carbohydrate and amino acid metabolism. In cephalopod muscle this is acheived by octopine dehydrogenase (E.C.1.5.1.11) , whereas in the oyster adductor muscle it is acheived by transaminases and malate dehydrogenase (E.C.1.1.1.37). Therefore studies of the catalytic properties (a) of octopine dehydrogenase from muscle of a group of cephalopods, and (b) of cytoplasmic aspartate aminotransferase (E.C.2.6.1.1) and malate dehydrogenase from adductor muscle of the oyster, Crassostrea gigas, were undertaken. Higher activities of octopine dehydrogenase were found in the mantle of Octopus ornatus than in the mantle of Symplectoteuthis oualaniensis, but the catalytic properties of both enzymes were similar. The affinity for pyruvate was low (Km approx. 1.7 mM), but increased with increasing concentrations of arginine; the affinity for arginine similarly increased with increasing concentrations of pyruvate. Octopine dehydrogenase from the spadix muscle of the chambered nautilus, Nautilus pompilius, had a higher affinity for pyruvate (Km approx. 0.3 mM), and this was also increased by increasing arginine concentrations. It is suggested that octopine dehydrogenase maintains redox balance in a manner analogous to lactate dehydrogenase (E.C.I.1.1.27), and closely couples glycolysis with arginine phosphate metabolism, such that an anaerobic reserve is provided for high intensity "burst" work. The octopus mantle relies on this mechanism more so than does the mantle of the oceanic squid, S. oualaniensis, and the Nautilus spadix muscle appears to use this anaerobic process for most of its energetic requirements. In contrast to cephalopod muscle, oyster adductor muscle maintains redox balance through coupling aspartate and alanine metabolism with carbohydrate fermentation. Adductor aspartate aminotransferase had a higher affinity for aspartate than for glutamate, and a higher affinity for 2-ketoglutarate than for oxaloacetate, suggesting that it would function more readily in the direction of aspartate utilization. Adductor malate dehydrogenase had a higher affinity for oxaloacetate than did aspartate aminotransferase, hence the major fate of oxaloacetate produced would be conversion to malate, and this would direct the flow of aspartate carbon towards succinate. Since adductor alanine aminotransferase (E.C.2.6.1.2) is kinetically adapted for alanine formation, these enzymes couple glycolysis with aspartate mobilisation, such that alanine is formed from glucose and succinate from aspartate. In addition,it was found that pyruvate had another possible fate during anoxia in the adductor, that is conversion to an as yet unidentified compound that is produced by a dehydrogenase requiring NADH, alanine and pyruvate as substrates. This enzyme has an extremely low affinity for alanine, and is potently inhibited by succinate at low pH; hence during anoxia production of this compound would be limited, and the pathway leading to succinate production favoured. / Science, Faculty of / Zoology, Department of / Graduate

Acteon (Rictaxis) punctocoelata (Carpenter) is a primitive opisthobranch mollusc found sporadically in central California bays. The primitive nature of this genus is indicated both geologically and morphologically (Fretter and Graham, 1954 and Morton, 1958). This micro-phagous browser burrows just below the surface of the sandy mudflats, as do its close relatives Harninea, Scaphander, and Philine (Fretter and Graham, 1954). Its strong, sculptured external shell is approximately 1/2 inch long and is encircled with narrow black· bands that follow the whorls around the white shell (Fig. 1).

No description available.

No description available.