Adhesion at the Posterior End of Monopisthocotylean Monogeneans
Posterior gland cells in larvae have been studied only at the level of the light microscope. It was mentioned above Section 5.2.1 that larvae of Monocotyle spiremae Monocotylidae have two posterior gland cells containing granular secretion, one on each side of the body, near the haptor Figure 14 . Neither ducts nor pores associated with them in this or other monocotylid larvae have been observed Chisholm and Whittington, 1996a . The larvae of other monopisthocotyleans such as the capsalids E....
References 1
Adams, J., Greenwood, P. and Naylor, C. 1987 . Evolutionary aspects of environmental sex determination. International Journal of Invertebrate Reproduction and Development 11, 123-136. Anderson, R.M. and May, R.M. 1981 . The population dynamics of microparasites and their invertebrate hosts. Philosophical Transactions of the Royal Society of London, B 291,451-524. Andreadis, T.G. 1983 . Life cycle and epizootiology of Amblyospora sp. Microspora Amblyosporidae in the mosquito, Aedes cantator....
Attachment By Adhesives In The Turbellaria
Turbellarians include free-living representatives such as the acoels, rhabdo-coels, triclads and polyclads as well as some groups that can form associations or relationships with invertebrates and vertebrates, such as some species of polyclads and triclads, the temnocephalans, umagillid and graffillid rhabdo-coels and the fecampiids Kearn, 1998 . The name 'Turbellaria' refers to a group of flatworms that are now known to be paraphyletic Rieger et al., 1991 Rohde, 1994b Whittington, 1997 and in...
Adults
Gland cells are described occasionally in association with the suckers of some mature digeneans e.g. Halton, 1967 Halton and Dermott, 1967 and mucopolysaccharide secretions were tentatively implicated in adhesion or extracorporeal digestion by Halton and Dermott 1967 . In addition to suckers, mechanical specializations for attachment in adult flukes include a spiny, retractable proboscis, reminiscent of the proboscis of acanthocephalans, on either side of the oral sucker in Rhopalias spp....
Adhesion in Polyopisthocotylean Monogeneans
Fewer comprehensive studies of gland cells in larval polyopisthocotyleans exist but Whittington et al. 2000b review these. Figure 19 illustrates the arrangement and content of gland cells for the larva of Grubea cochlear Mazocraeidae to demonstrate the main features for a polyopisthocotylean as determined using light microscopy. A set of gland cells on either side of the pharynx and a second set laterally on either side of the body posterior to the pharynx, both with gland ducts leading...
The Aspidogastrea
The Aspidogastrea, although a minor group of the parasitic Platyhelminthes see Rohde, 1994c in terms of diversity, numbers of species and host range, occupies an important phylogenetic position. Aspidogastreans are considered to be primitive neodermatans and represent either the sister group to the Digenea or the sister group to all other Neodermata see Rohde, 1994b . Most classification schemes place the Aspidogastrea as a subclass in the Trematoda. Comparatively little is known of their...
Acknowledgements
We thank many of our colleagues who have contributed to this review in different ways. For donating specimens for SEM Figures 3B, 22,23 , we are indebted to Dr Tom Cribb Department of Microbiology and Parasitology DoMP at The University of Queensland UQ , Brisbane, Queensland, Australia . We are grateful to Dr Mai Jones Centre for Microscopy and Microanalysis CMM , UQ for the kind contribution of some of his unpublished TEM photographs Figures 20, 21 identifying the trypanorhynch metacestode in...
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Figure 12 Diagram to demonstrate the looping locomotion of monogenean parasites based on observations of Neoheterocotyle rhinobatidis Monopisthocotylea Monocotylidae moving across glass surfaces and epithelial surfaces of the gill lamellae of its elasmo-branch host. A. The resting posture of the parasite with the posterior haptor bearing hooks attached firmly but the anterior end is detached and free to move around. B and C. Remaining attached firmly by the haptor, the parasite stretches its...
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Figure 7 Phylogeny constructed by maximum likelihood analysis of partial DNA polymerase and RNA polymerase gene sequences of Leishmania and Endotrypanum species analyses were performed using the program DNAML in PHYLIP Felsenstein, 1993 . The phylogeny was artificially rooted on the mid-point using RETREE this midpoint root is supported by the position of the root of the Leishmanial Endotrypanum clade in the partial 18S rRNA phylogeny Figure 6 . Sequences are taken from the work of Croan et al....
Phylogenetic Considerations
The Platyhelminthes are regarded by many to occupy a pivotal position in the Animal Kingdom. Willmer 1990 commented that the flatworms may have provided the base from which higher metazoans of many different kinds launched. Since the Platyhelminthes comprise three major wholly parasitic assemblages and one largely free-living group, it is hardly surprising that the extant free-living turbellarians are such a focus for phylogenetic study. A good overview of turbellarian phylogeny is provided by...
Freeliving Turbellarians with a Duogland System
Comparative ultrastructural studies summarized by Tyler 1976 have demonstrated that the adhesive systems of the following rhabditophoran turbellarian orders are composed of three distinctive cell types comprising two gland cell types and one non-glandular cell type Figures 5, 6 Haplopharyngida Macrostomida Polycladida Rhabdocoela the Rhabdocoela 'Typhloplanoida' and Rhabdocoela Kalyptorhynchia of Ehlers and Sopott-Ehlers, 1993 Proseriata marine Tricladida. Tyler 1988 added the freshwater...
Adhesive And Other Gland Cells In The Cestodes
Here the cestodes include the eucestodes, gyrocotylids and amphilinids following Rohde 1994b and we treat each group separately. To the lay person, the principal attachment organ of the true tapeworms Eucestoda , the anterior scolex e.g. Figure 3A , is probably the most quintessential of parasite holdfasts. The scolex can be provided with shallow grooves, suckers of various kinds, hooks, spines, tentacles and glands or combinations of these, but it can also be simple or absent. The mode of...
Mechanisms Of Transovarial Transmission
Understanding of the mechanisms involved in parasite movement within the host and in transovarial transmission is limited. In the majority of studies, for example, Nosema heliothidis infecting the hymenopteran Campoletis sonoren-sis Brooks and Cranford, 1972 , parasites have been observed in the adult female host reproductive tissue and then in host eggs, thus establishing that transovarial transmission occurs, but giving no detailed information on mechanisms. In this section we examine the...
Adhesion at the Anterior End of Monopisthocotylean Monogeneans
The larvae of the Monogenea, including their gland cells, have been reviewed extensively by Whittington et al. 2000b , to which the reader is referred for more detail. Anterior gland cells are conspicuous in most larvae oncomiracidia at the level of the light microscope and we use the larva of the monocotylid Monocotyle spiremae Figure 14 , examined in detailed by Chisholm and Whittington 1996a , to demonstrate their arrangement and contents for a typical monopisthocotylean. The gland cells...
Adhesion in Symbiotic Turbellarians
The duo-gland adhesive system described above applies to several taxa of free-living turbellarians, including the Rhabdocoela 'Kalyptorhynchia' and Rhabdocoela 'Typhloplanoida' from Tyler 1976, 1988 . Different systems appear to occur in symbiotic turbellarians. Studies by Jondelius 1992 on four species of the Pterastericolidae, a family of rhabdocoels symbiotic inside the digestive system of starfish, described the ultrastructure of a prominent complex of eosinophilic glands Figure 9A...
The Array of Gland Cells and Secretory Products in Turbellarians
There is a bewildering assemblage of epidermal and subepidermal gland types among turbellarians, but little is known of the composition or function of most of them Rieger et al., 1991 . Most glands are unicellular. The gland cell bodies lie in the parenchyma and ducts usually termed 'necks' in the turbellarian literature because they stand proud of the surrounding epidermis to form a papilla open between or through epidermal cells Figure 5 . A single Figure 5 Diagram of typical duo-gland system...
Mp 98765432 I
C. Bryant Division of Biochemistry and Molecular Biology, The Australian National University, Canberra, ACT 0200, Australia M. Colluzi Director, Istituto di Parassitologia, Universit Degli Studi di Roma 'La Sapienza', P. le A. Moro 5, 00185 Roma, Italy C. Combes Laboratoire de Biologie Animale, Universit de Perpignan, Centre de Biologie et d'Ecologie Tropicale et M diterran enne, Avenue de Villeneuve, 66860 Perpignan Cedex, France W.H.R. Lumsden 16A Merchiston Crescent, Edinburgh, EH10 5AX, UK...
Introduction
Parasites within the family Trypanosomatidae have either a mono- or digenetic life cycle. It seems intuitively obvious to expect the digenetic parasites to have more complex evolutionary histories than trypanosomatids with a single host, since the evolutionary pressures on two different hosts would be more varied and cumulatively greater. For most of the twentieth century, ideas on trypanosomatid evolution have had to be based on morphological and life cycle data, despite their known...