Ultrastructural study on the body surface of the acanthocephalan parasite Dentitruncus truttae in brown trout

Abstract

Scanning electron microscope (SEM) investigations on the holdfast elements, proboscis hooks, and trunk spines of Dentitruncus truttae (Acanthocephala, Palaeacanthocephala), an endoparasite of Salmo trutta (brown trout), provide more data about the surface of these taxonomic relevant structures. In both acanthocephalan sexes, the fully everted cylindrical proboscis possessed 18 longitudinal rows of hooks with 18 hooks per row (rarely 19-20). Hook length varied according to position on the proboscis; apical hooks were 40-52 microm long, middle hooks were 31.7-36.6 microm, and basal hooks were 38.1-40 microm. Starting from the anterior end of the metasoma, numerous cuticular spines (26.7-30 microm in length) were visible and their number progressively decreased posteriorly. SEM observations of D. truttae hooks and spines revealed the presence of many surface striations on each proboscis hook. These surface striations were absent from trunk spines. From the base of the hook, the striations ran parallel toward the point of convergence. Additionally, survey of longitudinal and transversal sections of the hook using transmission electron microscope confirmed that the hook surface was not smooth. SEM comparison with the hooks of several palaeacanthocephalan species, as well as with the hooks of species belonging to Eoacanthocephala and Polyacanthocephala, indicated that the striations are currently exclusive to D. truttae proboscis hooks.

Fine structure of Longicollum pagrosomi (Acanthocephala: Pomphorhynchidae) and intestinal histopathology of the red sea bream, Pagrus major, infected with acanthocephalans

“…The apical hooks were the longest (40.0-52.0 μm), and the middle hooks were the shortest (31.7-36.6 μm). Numerous (Dezfuli et al 2008). In this study, P laevis had vertically arranged hooks which were approximately 40 μm in length, and they exited only on the proboscis.…”

“…In the past, most of the acanthocephalan studies have been focused on taxonomic features and pathological changes observed by light microscope (Chaicharn and Bullock 1967;Hatai et al 1987;Roubal 1993;Dezfuli et al 2008). Recently, scanning electron microscopy (SEM) has been proven useful for studying the hook and tegument features of acanthocephalans and the morphology of alterations of the digestive tract (Wayland et al 2004;Alava and Aguirre 2005;Bayoumy et al 2006).…”

Redescription of Rhadinorhynchus ornatus (Acanthocephala: Rhadinorhynchidae) from Skipjack Tuna, Katsuwonus pelamis, Collected in the Pacific Ocean off South America, with Special Reference to New Morphological Features

“…The surface striations noted on the proboscis hooks have been previously reported in only 1 acanthocephalan species, Dentitruncus truttae Sinzar, 1955 (Palaeacanthocephala) by Dezfuli et al (2008). Trunk spines in both D. truttae and R. ornatus had unstriated smooth surfaces.…”

New Features ofNeoechinorhynchus(Neoechinorhynchus)dimorphospinus(Acanthocephala: Neoechinorhynchidae) from Recent Collections in the Arabian Gulf Using SEM, with Notes on Histopathology

“…In addition to their present reporting in N. dimorphospinus (Eoacanthocephala: Neoechinorhynchidae), ribbed hooks have also been reported in 3 other species in 2 other families of Palaeacanthocephala: Dentitruncus truttae Sinzar, 1955 (Illiosentidae), Rhadinorhynchus ornatus Van Cleave, 1918 (Rhadinorhynchidae), and Leptorhynchoides polycristatus Amin, Heckmann, Halajian, El-Naggar, Tavakol, 2013 (Rhadinorhynchidae). Dezfuli et al (2008) and Amin et al (2009) suggested that such hook striations may provide a more effective attachment to the host's intestine. The striations of the hooks of D. truttae appeared as small dents on the outer periphery of the hooks' outer striped layer (Dezfuli et al, 2008).…”

“…Dezfuli et al (2008) and Amin et al (2009) suggested that such hook striations may provide a more effective attachment to the host's intestine. The striations of the hooks of D. truttae appeared as small dents on the outer periphery of the hooks' outer striped layer (Dezfuli et al, 2008).…”