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Title: Some aspects of the immunobiology of Saccoglossus ruber (Hemichordata) and Branchiostoma lanceolatum
Author: Millar, D. A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1991
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The work embodied in this thesis concerns the host defence mechanisms of the hemichordate, Saccoglossus ruber and the cephalochordate, Branchiostoma lanceolatum. Initially the cellular repsonses of these animals towards experimentally introduced foreign particles were examined. S. ruber possesses avidly phagocytic coelomocytes which were studied in vitro and in vivo, and shown by light and electron microscopy to be of a single morphological type. These coelomocytes probably originate from the coelomic lining, but autoradiography failed to substantiate this. The cellular response in B. lanceolatum towards wounding and subcutaneously injected bacteria was very limited. Even after 7 days, a relatively small number of coelomocytes accumulated at the site of injection. These coelomocytes contained phagocytosed bacteria and formed the beginning of nodule-like structures. In the majority of sections, the bacteria were observed surrounded by an unidentifiable amorphous material. Haemagglutinins and antibacterial factors were also detected in whole body homogenates of S. ruber and B. lanceolatum. The haemagglutinins from both animals were proteinaceous and functioned independently of Ca++ and Mg++. The S. ruber agglutinin showed specificity for D-galactose containing carbohydrates, whereas no clear-cut carbohydrate specificity could be discerned with the B. lanceolatum agglutinin. The S. ruber agglutinin was also associated with the mucus covering the body surface, and the B. lanceolatum agglutinin with mucus in the pharynx. Antibacterial activity in S. ruber was strongest against natural bacterial isolates. The active factor, which may be a bromophenol, was heat stable, dialyzable, bactericidal in its mode of action and also associated with the body surface mucus. The B. lanceolatum antibacterial factor was bacteriostatic, probably proteinaceous, heat labile and operated over a wide temperature range. At a protein concentration above 5 mg ml-1, the antibacterial proteins aggregated and could be disassociated only at high pH. A role for these humoral factors in the defence systems of the experimental animals is discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available