title: Preliminary characterization of the lipid and protein components of the protective surface membranes of a pentastomid Porocephalus crotali.
abstract: All instars of the pentastomid Porocephalus crotali, in the tissues of rat intermediate hosts and the lung of rattlesnake definitive hosts, are covered by a vesicular or stacked membranous secretory product which is synthesized in sub-parietal cells (SPC) and channelled to the cuticle via multitudinous chitin-lined ducts. In rats this enveloping foam of vesicles survives for the duration of a cuticle. We have purified and partially characterized the lipid and protein composition of lamellate droplets from SPC of infective nymphs. Lipids in the droplets comprised a mixture of neutral and polar lipid classes with cholesterol being the major neutral lipid and phosphatidylcholine the dominant polar lipid. In addition, Triton X-114 phase separation of the protein component of droplets partitioned these into an aqueous phase (with a major band at 60 kDa), a detergent phase with two hydrophobic polypeptides (24 and 16 kDa) and an insoluble pellet containing several minor proteins and major bands at 31 and 107 kDa. Western blotting, with rabbit anti-lamellate droplet antiserum, strongly label only the 60 kDa and the two hydrophobic proteins. Significantly no proteins at all label with serum from infected rats from 50-150 days post-infection, a finding endorsed by indirect fluorescent antibody tests on sectioned V-VII stage nymphs. Possible immunomodulatory functions of SPC-derived surface membranes are discussed and, in this regard, they are compared with pulmonary surfactant, a product of alveolar Type II cells which lines all vertebrate lungs.
authors.affiliation: Department of Biological Sciences, University of Dundee, Scotland.
authors.forename: D A
authors.initials: DA
authors.lastname: Jones
authors.forename: R J
authors.initials: RJ
authors.lastname: Henderson
authors.forename: J
authors.initials: J
authors.lastname: Riley
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D003445:Crustacea / Q000737:chemistry* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000032:analysis; D005455:Fluorescent Antibody Technique; D008563:Membrane Lipids / Q000032:analysis* / Q000737:chemistry; D008565:Membrane Proteins / Q000032:analysis* / Q000737:chemistry; D008854:Microscopy, Electron; D009758:Nymph / Q000737:chemistry / Q000648:ultrastructure; D012911:Snakes / Q000469:parasitology*
chemical_list: D005227:Fatty Acids; D008563:Membrane Lipids; D008565:Membrane Proteins