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Biomedical subjects

J Riley

Publications and source records attributed to J Riley.

At least 127 records · Page 7Linked to original sources
PubMed1975

Competition between two closely related Tetrabothrius cestodes of the fulmar (Fulmarus glacialis L.).

The two congeneic Tetrabothrius cestodes of the fulmar are so closely related that they can only be reliably distinguished by differences in the number of testes. The two species show a considerable distributional overlap along the intestine. Statistically it can be shown that high numbers of the common, anteriorly situated species (T. minor) affect the distribution of the rarer, more posteriorly situated species (T. procerus), causing the latter to occupy a more posterior site in the intestine. Several possibilities are discussed concerning the mechanism by which T. procerus is affected, and how this mildly competitive situation is maintained. It is probable that niche segregation between the two species is more or less complete, but that this is reinforced in concurrent infections by interactive site segregation.

Animals↗
PubMed1975

Some ultrastructural observations on the integument of a pentastomid.

The cuticle of the cephalobaenid pentastomid Reighardia sternae is described at various stages of the moult-intermoult cycle. The intermoult cuticle comprises four layers: an outer epicuticle; an underlying dense layer, the protein epicuticle; a fibrillar endocuticle; and a denser subcuticle. The overall similarity between the structure and composition of these layers and those of insects is discussed. However, the orientation of the chitin-protein fibres in the endocuticle does not show the rotating structure characteristic of many arthropod species, but this does appear in the sclerotized hooks. It is suggested that this comparatively loose, poorly oriented endocuticular structure produces a highly extensible cuticle which is precisely adapted to the specialize, endoparasitic habit of this species. Events at ecdysis, particularly the secretion of moulting fluid and the deposition of cuticulin, follow the insect pattern precisely. The phyletic significance of these observations is discussed.

Animals↗
PubMed1975

An experimental investigation of a direct life-cycle in Reighardia sternae (Diesing, 1864), a pentastomid parasite of the herring gull (Larus argentatus).

A direct life-cycle in Reighardia sternae, a cephalobaenid pentastomid of gulls was investigated: the work was prompted by a report of eggs and larvae recovered from the stomach and intestine of a naturally infected gull. Infective pentastomid eggs were obtained by surgically transplanting maturing female Reighardia, taken from freshly shot wild gulls, into captive recipients. Faecal material from birds thus artificially infected was collected daily and examined for eggs. Eggs were force fed to 33 hand-reared (from eggs or nestlings) juvenile gulls which were selected at random and sacrificed at intervals thereafter and examined for pentastomids. One hour after infection, primary larvae appear in the body cavity where they moult immediately. They grow steadily and by 27-35 days are sexually differentiated, and by 66 days have copulated. Fertilized females take a further 116 days to produce eggs by which time they are 7-6 cm long. The complex migrations undertaken by developing larvae in the gull, and the problems of the mechanism of direct transmission, are discussed.

Air Sacs↗