Ultrastructure and small-subunit ribosomal DNA sequence of Henneguya lesteri n.sp. (Myxosporea), a parasite of sand whiting Sillago analis (Sillaginidae) from the coast of Queensland, Australia

Abstract

Henneguya lesteri n. sp. (Myxosporea) is described from sand whiting, Sillago analis, from the southern Queensland coast of Australia. H. lesteri displays a preference for the pseudobranchs and is typically positioned along the afferent blood vessels, displacing the adjoining lamellae and disrupting their normal array. The plasmodia appeared as whitish-hyaline, elliptical cysts (mean dimensions 230 × 410 µm) attached to the oral mucosa lining of the hyoid arch on the inner surface of the operculum. Infections of the gills were also found, in which the plasmodia were spherical, averaged 240 × 240 µm in size and were located on the inner hemibranch margin. The parasites lodged in the gill filament crypts and generated a mild hyperplastic response of the branchial epithelium. In histological sections, the plasmodium wall and adjoining ectoplasm appeared as a finely granulated, weakly eosinophilic layer. Ultrastructurally, this section of the host-parasite interface contained an intricate complex of pinocytotic channels. H. lesteri is polysporic, disporoblastic and pansporoblast forming. Sporogenesis is asynchronous, with the earliest developmental stages aligned predominantly along the plasmodium periphery, and maturing sporoblasts and spores toward the center. Ultrastructural details of sporoblast and spore development are in agreement with previously described myxosporeans. The mature spore is drop-shaped, length (mean) 9.1 µm, width 4.7 µm, thickness 2.5 µm, and comprises 2 polar capsules positioned closely together, a binucleated sporoplasm and a caudal process of 12.6 µm. The polar capsules are elongated, 3.2 × 1.6 µm, with 4 turns of the polar filament. Mean length of the everted filament is 23.2 µm. Few studies have analyzed the 18S gene of marine Myxosporea. In fact, H. lesteri is the first marine species of Henneguya to be characterized at the molecular level: we determined 1966 bp of the small-subunit (18S) rDNA. The results indicated that differences between this and the hitherto studied freshwater Henneguya species are greater than differences among the freshwater Henneguya species.KEY WORDS: Marine Myxosporea · Pseudobranchs · Gills · Ultrastructure · 18S rDNA gene sequence Resale or republication not permitted without written consent of the publisherDis Aquat Org 46: 197-212, 2001 corded Henneguya spp. from Australia are 4 unidentified species from freshwater fish (O'Donoghue & Adlard 2000) and 2 from coastal marine fish: Henneguya spp. from yellowfin bream Acanthopagrus australis (Gunther 1859) in Queensland (Roubal 1994) and grey mullet Mugil cephalus Linnaeus 1758 in New South Wales (Lom et al. 1992).The present study describes a new species, Henneguya lesteri n. sp., from the pseudobranch and gills of sand whiting Sillago analis from a mangrove mud flat and a sandy beach at Moreton Bay, Queensland, Australia. MATERIALS AND METHODS Collection of material. Twenty-three sand whitingSillago analis Whitley 1943 were collected from 2 coastal sites of Moreton Bay during 2 sampling periods in...

Histology, ultrastructure and prevalence of Henneguya piaractus (Myxosporea) infecting the gills of Piaractus mesopotamicus (Characidae) cultivated in Brazil

“…A similar organization of the plasmodial surface has been described in Henneguya listerine (Hallett & Diamant 2001) and for the interlamellar plasmodia of Henneguya exilis (Current & Janovy 1976). In H. exilis, regions of the plasmodial surface are in direct contact with the host cells, with the cytoplasm of the host cell appearing to pass into pinocytic canals of the plasmodial wall (Current & Janovy 1976).…”

“…The plasmodial wall of Henneguya piaractus consisted of a single membrane, as in other myxosporean species (Current & Janovy 1978, Current 1979, Hallett & Diamant 2001, Dohole et al 2002, and contained pinocytic canals that extended into the plasmodial ectoplasm, as also seen in several other Henneguya species (Current & Janovy 1976, Current 1979, Rocha et al 1992, Hallett & Diamant 2001, Azevedo & Matos 2002, El-Mansy & Bashtar 2002. However, there was no coat, nor was the wall surrounded by a capsule of collagen fibres.…”

New data on Soricimyxum fegati (Myxozoa) including analysis of its phylogenetic position inferred from the SSU rRNA gene sequence

“…Myxosporean specific primers MyxospecF and MyxospecR (Fiala 2006) were used for the following PCR. In order to obtain complete SSU rDNA sequence, additional PCRs were done with following primers: ERIB1 + ACT1R (Hallet and Diamant 2001) and MYXGEN4f (Kent et al 2000) + ERIB10. The amplicons of three samples were isolated from 1.0% agarose gels and cloned into the pDrive Cloning Vector using QIAGEN PCR Cloning Kit (QIAGEN GmbH, Hilden, Germany).…”

Complete life cycle of Myxobolus rotundus (Myxosporea: Myxobolidae), a gill myxozoan of common bream Abramis brama

“…For sequencing, second-round PCRs were used to generate 2 overlapping templates with primer pairs ERIB1 and ACT1r (Hallett & Diamant 2001), and MyxGen4f (Diamant et al 2004) and ERIB10. Reagent amounts were scaled up to 50 µl reactions, included 1.25 µl of the ERIB1/ERIB10 template, and the above cycling profile used with the extension step shortened to 60 s. Aliquots of the resultant PCR products were electrophoresed through a 1% agarose 1× Trisacetate-EDTA (TAE) buffer gel stained with SYBR Safe (Invitrogen) alongside a 1 kb+ DNA ladder (Invitrogen) to confirm that only a single amplicon of expected size was present.…”