The hatching of Hymenolepis diminuta eggs and penetration of the hexacanths in Tenebrio molitor beetles

Parasitology ◽  
1971 ◽  
Vol 62 (3) ◽  
pp. 445-456 ◽  
Author(s):  
R. C. Lethbridge
Keyword(s):  
Research Council ◽  
Science Research ◽  
Tenebrio Molitor ◽  
Imperial College ◽  
Hymenolepis Diminuta ◽  
Stage Process ◽  
Research Facilities ◽  
Midgut Lumen ◽  
Science Research Council

The hatching of Hymenolepis diminuta eggs and penetration of the emergent hexacanths in adult and larval Tenebrio molitor beetles had been described. Hatching was shown to be a two-stage process involving rupture of the eggshell by the insect's mandibles and digestion of the remaining egg-layers in the midgut lumen. Penetration of hatched embryos was examined by histological methods that demonstrated the rate of migration and the route taken by hexacanths entering the haemocoel of adult beetles. Differences in the arrangement of the midgut tissues in adult and larval T. molitor were detected and shown to account for the failure of hexacanths to complete migration in the larvae. The role of the embryonic hooks and penetration gland secretions during hatching and penetration has also been discussed.I should like to thank Professor T. R. E. Southwood for providing generous research facilities, Dr June Mahon for her advice and encouragement, and in particular, Dr W. Mordue for his continuous interest and many useful criticisms. This work was conducted during the tenure of a Science Research Council Studentship at Imperial College of Science and Technology, London, S.W. 7.

The occurrence of Diplozoon paradoxum Nordmann, 1832 (Trematoda: Monogenea) in certain waters of northern England and its distribution on the gills of certain Cyprinidae

Parasitology ◽  
1968 ◽  
Vol 58 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Michael Wiles
Keyword(s):  
Research Council ◽  
Science Research ◽  
Rutilus Rutilus ◽  
Abramis Brama ◽  
Critical Reading ◽  
Phoxinus Phoxinus ◽  
The Right ◽  
The University ◽  
Research Facilities ◽  
Science Research Council

The monogenean Diplozoon paradoxum occurs on Abramis brama, Gobio gobio, Phoxinus phoxinus and Rutilus rutilus in northern England. In any one area, the infection is present in some waters but absent in others and predominates in rivers rather than in ponds or reservoirs.D. paradoxum is randomly distributed on the gills, sides of the gill apparatus, hemibranchs and surfaces of primary lamellae of G. gobio, P. phoxinus and R. rutilus (except for P. phoxinus where inner hemibranchs carry more worms), but prevails on median sectors of the gills of these hosts. In A. brama the parasite is more numerous on certain gills, on the right side of the gill apparatus, and on the inner hemibranchs, but is randomly disposed on primary lamellar surfaces and along the gills. Except on G. gobio attachment is predominantly to two primary lamellae rather than one. This may reduce dislodging effects of the gill ventilating current by leaving portions of the lamellar surfaces unoccupied and allowing unimpeded flow in these regions.This work was conducted during tenure of a Science Research Council Research Studentship. Research facilities in the Department of Zoology, University of Leeds, were kindly provided by Professor J. M. Dodd. Other facilities in the Biological Station, St John's, Newfoundland, were provided by the Director, Dr W. Templeman. Statistical advice offered by Dr E. Broadhead, Department of Zoology, and Professor C. L. Oakley, Department of Bacteriology, both of the University of Leeds, is gratefully acknowledged. I am indebted to Dr R. Wynne Owen, Department of Zoology, for constant advice and encouragement and for critical reading of the manuscript.

The chemical composition and some properties of the egg layers in Hymenolepis diminuta eggs

Parasitology ◽  
1971 ◽  
Vol 63 (2) ◽  
pp. 275-288 ◽  
Author(s):  
R. C. Lethbridge
Keyword(s):  
Amino Acid ◽  
Research Council ◽  
Proteolytic Enzymes ◽  
External Environment ◽  
Science Research ◽  
Hymenolepis Diminuta ◽  
Toxic Compounds ◽  
Shell Protein ◽  
Formed Part

SUMMARY1. It has been shown that the protein eggshell of Hymenolepis diminuta eggs was not significantly stabilized by sulphur or electrovalent linkages but was resistant to attack by proteolytic enzymes. Amino acid analysis demonstrated a marked preponderance of aromatic and heterocyclic acids and it has been suggested that these groups act as cross-linking agents in the shell protein.2. The role of the lipid-containing subshell ‘membrane’ in protecting the enclosed embryo against fluctuations in pH and osmolarity in the external environment and infiltration of enzymes and toxic compounds has been demonstrated.3. The cytoplasmic layer was shown to consist of a glucosamine-containing mucoprotein present in a dehydrated or semi-dehydrated state in the intact egg.In mechanically damaged eggs the cytoplasmic layer was rapidly dispersed by some proteolytic enzymes.4. The embryophore enclosing the hexacanth embryo was composed of a sulphurrich protein that was weakened by some proteolytic enzymes and completely destroyed by others.I should like to thank Professor T. R. E. Southwood, in whose department this work was carried out, and Dr June Mahon for her advice and encouragement.I am particularly grateful to Dr R. A. Wilson, Department of Biology, University of York, for the quantitative amino acid determinations on eggshell hydrolysates and for criticizing this manuscript. This research was conducted during the tenure of a Science Research Council Studentship and formed part of a thesis submitted for the Ph.D. degree, University of London.

Sign in / Sign up

Export Citation Format

Share Document