Contents

Contributors to Volume 48 v vii The Molecular Evolution of Trypanosomatidae J.R. Stevens, H.A. Noyes, C.J. Schofield and W. Gibson Abstract 2 1. Introduction 2 2. The Evolution of the Trypanosomatids 3 3. The Evolution of Parasitism 7 4. Genus Trypanosoma II 5. Genus Leishmania 31 6. Conclusions 42 Acknowledgements 42 42 Transovarial Transmission in the Microsporidia A.M. Dunn, R.S. Terry and J.E. Smith Abstract 1. Introduction 2. Mechanisms of Transovarial Transmission 70 3. Transmission...

Adhesive Secretions on Monogenean Eggs

Section 4.7 highlighted the fact that some temnocephalans attach their eggs by adhesives to the surfaces of their hosts. This strategy has been employed by very few monogeneans because the majority of species lay eggs that are deposited freely into the water column. Fried and Haseeb (1991) commented that 'filaments of monogenean eggs presumably have adhesive properties that help attach the eggs to a host or substratum'. Such reports are relatively rare (Kearn, 1986), however, and surface...

V

Figure 2 Diagrammatic representation of the life cycle of Amblyospora connecticus. This microsporidian has alternating horizontal and vertical transmission and has an indirect life cycle involving a mosquito and a copepod intermediate host. Solid line represents horizontal transmission, dashed line indicates vertical transmission, dotted line indicates transtadial transmission. Figure 2 Diagrammatic representation of the life cycle of Amblyospora connecticus. This microsporidian has alternating...

Adhesive And Other Gland Cells In The Digenea

The principal attachment organs in adult digeneans are the muscular suckers (Figure 3B). There is usually, but not always, a powerful oral sucker surrounding the mouth and most also have a ventral sucker, the position of which can be variable depending on the taxon. The functional morphology of suckers has been determined (e.g. Halton, 1967 Smyth and Halton, 1983) and movement like a leech by alternately attaching one or other sucker is known (Fairweather et al., 1983 Sukhdeo and Mettrick, 1986...

Chemistry of Monogenean Adhesives

Little is published about the chemistry of monogenean adhesive secretions and what is known is based on histochemistry. The anterior head glands of Leptocotyle minor (Microbothriidae) stain well with Ehrlich's haematoxylin and with neutral red (Kearn, 1965), those of Udonella (Udonellidae) are eosinophilic and granular rather than mucoid (Nichols, 1975) and Lyons (1968) found mucoprotein in anterior secretions of Entobdella soleae (Capsalidae). Kritsky (1978), El-Naggar and Serag (1987) and...

Tissue Adhesion Temporary Adhesion to Living Surfaces

All of the above examples relate to the importance of adhesion for free-living organisms, mostly but not exclusively in a marine environment, to maintain secure attachment to inert, abiotic substrates. Walker (1987) states that any surface placed in sea water becomes coated rapidly by a monolayer of polymeric material comprising deposited or adsorbed macromolecules, most of which are proteins. Subsequently, bacteria attach to the 'conditioning film' and form the 'primary film' (Walker, 1987)....

The Ecology And Evolution Of Transovarially Transmitted Microsporidia

Microsporidia

Transovarially transmitted microsporidia can shed light on some key areas in the evolutionary ecology of parasitism. The use of both horizontal and transovarial transmission routes provides an opportunity to examine current theories for the evolution of virulence. In addition, transovarially transmitted microsporidia can manipulate their hosts through sex ratio distortion. We consider the implications of parasitic sex ratio distortion for host population sex ratio and stability. 4.1. The...

Adhesive Secretions on Turbellarian Eggs

There are cases in which some turbellarians and monogeneans (Section 5.5) use substances that appear to have adhesive properties to attach their eggs (taken here to mean a shelled zygote after Kearn, 1986). Among turbellarians this seems to be a strategy employed by some temnocephalans. Notodactylus handschini, an ectosymbiont of the crayfish Cherax quadri-carinatus, is an inactive worm and may spend many days (perhaps its whole life ) attached in the same location at the edges of the host's...

Info

Gammarus Duebeni

Microsporidia also cause disease in fish, particularly in commercial hatcheries (Hauck, 1984 Kent et al., 1989) and aquaria (Lorn et al., 1995). Disease pathogenesis varies, with some genera such as Glugea and Loma causing the formation of xenomas. The xenoma is formed as a result of hypertrophy of the infected cell. The resulting structure is up to several millimetres in diameter, the internal cytoplasm is filled with developing parasites and the membrane specialized for nutrient uptake...

Parasitology

Introduction Parasitology

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Abstract

In the absence of a fossil record, theories relating to the evolution of protozoa have, for most of the twentieth century, been based on morphological and life cycle data despite their known limitations. However, recent advances in molecular methodology, notably the wide availability of accurate, automated DNA sequencing, have made it possible to deduce the evolutionary relationships of extant species from their genes. This paper focuses on new findings concerning the evolution of the...

Comparison Of Platyhelminth Adhesives With Temporary Adhesives In Other Marine Macroinvertebrates

Temporary adhesion Section 3.3 is known for a range of marine invertebrates other than platyhelminths, including gastrotrichs Tyler and Rieger, 1980 , polychaetes Gelder and Tyler, 1986 and nematodes Tyler and Melanson, 1979 , but there are few examples from marine macroinvertebrates of temporary adhesives that have been characterized chemically. The composition of adhesives in echinoderms see review by Flammang, 1996 Flammang et al., 1998 and limpets Mollusca see Grenon and Walker, 1978, 1980...

Transmission Strategies And Parasite Maintenance

Microsporidian life cycles are complex, can involve a number of transmission routes and may require more than one host species. For the majority of microsporidian parasites, horizontal transmission is the major transmission route Canning and Lom, 1986 . However, for many microsporidia of invertebrates, transovarial transmission is also important for parasite maintenance in the host population. In this section, we review the transmission strategies employed by these microsporidia and their...

Pictures Of Entobdella Parasite

Acanthocephala Anatomy

Attachment to a host is fundamental to the survival of many parasites. Parasites may invest considerable time and energy in reproducing themselves, in locating and then infecting their host organisms, which are often specific species or small groups of species host-specificity e.g. Noble et al., 1989 Rohde, 1993, 1994a . When their host has been located and or infected, most parasites must attach themselves immediately at the site of contact where they may remain or they may migrate to a new...

Adhesion at the Posterior End of Monopisthocotylean Monogeneans

Kearn Capsalidae

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

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

Bucephalidae

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

Hexabothrium Appendiculatum

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

Lobatostoma

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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Troglocephalus Rhinobatidis

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...

E

Leishmania Viannia Map

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

Free Living Turbellarian

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

Larve Phyllobothrium

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

Nosema Plodiae Kellen

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

Secretion Needle Microscopy

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

Adhesion Medicine

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

Duo Gland System

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

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

Tropical Medicine

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...