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1. The hyperparasitic microsporidium Amphiacantha longa Caullery et Mesnil, 1914 (Microspora: Metchnikovellidae) - description of the cytology, redescription of the species, emended diagnosis of the genus Amphiacantha and establishment of the new family Amphiacanthidae

Creator:
Larsson, J.I. Ronny
Format:
print
Type:
model:internalpart and TEXT
Subject:
Microspora, Amphiacanthidae, sporogony, ultrastructure, cytology, and Amphiacantha longa
Language:
English
Description:
The ultrastructural cytology and reproduction of Amphiacantha longa Caullery et Mesnil, 1914 is described. Mcrogonial reproduction was not observed. The sporogony follows two lines: free disporoblastic. and enveloped, polysporoblastic, involving sporoblast mother cells. The enveloped sporogony is endogenous in spore sacs of sporont origin, daughter cells are formed by vacuolation. Probably all stages have coupled nuclei. Both free and enveloped spores are equipped with an extrusion apparatus composed of a flat polar sac, a straight polar filament of manubrium type, and a posterior globular appendix. Manubrium and appendix are enclosed in a membraneous coat. Circular elements of coat material occur in the proximity of the extrusion apparatus. The membraneous coat and the surface layer of the manubrium penetrate the polar sac. The extrusion apparatus is located at the wide pole of the spore, the nuclei at the narrower pole. Hosts are gregarines of the genus Lecudina Mingazzini, living in the gut of the polychaete Lumbrinereis fragilis (O. F. Muller). The cytology and reproduction are discussed and compared to other genera of metchnikovellideans, to the chytridiopsid genera, and to microsporidia expressing the typical cytology for the group. Metchnikovellideans and chytridiopsids exhibit cytological and reproductive similarities. The species is redescribed, the diagnosis of the genus Amphiacantha Caullery et Mesnil, 1914 is emended, and the new family Amphiacanthidae, comprising the genera Amphiacantha and Amphiamblys Caullery et Mesnil, 1914, is established.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. The presence of sporogonic stages of Tetracapsuloides bryosalmonae in Icelandic salmonids detected using in situ hybridisation

Creator:
Svavarsdóttir, Fjóla Rut, Freeman, Mark A., Antonsson, Þórólfur, Árnason, Friðþjófur, and Kristmundsson, Árni
Format:
počítač and online zdroj
Type:
model:article and TEXT
Subject:
proliferative kidney disease, PKD, Arctic charr, brown trout, Atlantic salmon, sporogony, salmonid, and intratubular
Language:
English
Description:
Proliferative kidney disease (PKD) is a widespread temperature-dependent disease in salmonids caused by the myxozoan parasite, Tetracapsuloides bryosalmonae (Canning, Curry, Feist, Longshaw et Okamura, 1999) (Tb). Tb has a two-host life cycle, involving fish as an intermediate host and freshwater bryozoans as the definitive host. Although salmonids are acknowledged as hosts for the parasite, it is less clear which fish species are active hosts in the life cycle of Tb. Differences in infection dynamics have been observed between some fish species, which are thought to be related to the existence of two main Tb-strains, the American and European. Iceland, having three species of indigenous salmonids and positioned geographically between Europe and North America, is an ideal location to study the natural development of Tb in wild fish. The main aim of this study was to determine the genetic origin of Tb in Iceland and confirm whether mature spores are produced in Icelandic salmonids. In this study, Icelandic salmonids were infected with the European Tb-strain. In situ hybridisation revealed that intraluminal sporogonic stages, including mature spores, were commonly observed in all three salmonid species. The presence of intraluminal stages has previously been confirmed in brown trout Salmo trutta Linnaeus and Atlantic salmon S. salar Linnaeus in Europe, but they have only been observed in Arctic charr Salvelinus alpinus (Linnaeus) in North America, infected by the local strain. This is, therefore, the first time that sporogonic stages have been observed in Arctic charr in Europe, where fish are infected with the European Tb-strain. Our data strongly suggest that all the three salmonid species inhabiting Icelandic waters serve as active hosts in the life cycle of Tb. However, for full confirmation, transmission trials are needed.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Ultrastructure and localisation of late-sporogonic developmental stages of Sphaerospora ranae (Myxosporea: Sphaerosporidae)

Creator:
Jirků, Miloslav and Bartošová-Sojková, Pavla
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Amphibia, Anura, Europe, kidneys, myxospore, Myxozoa, Rana, sporogony, synchronisation, and in situ hybridisation
Language:
English
Description:
Data on external ultrastructure of myxospores and internal ultrastructure of advanced pseudoplasmodia and myxospores of topotypic samples of Sphaerospora ranae (Morelle, 1929) from Rana dalmatina Bonaparte are provided, together with in situ hybridisation results. In both frogs examined, the infection was restricted to renal tubules and corpuscles. The infection site restriction was confirmed by light and transmission electron microscopy, as well as by in situ hybridisation. In addition, large myxospore masses measuring up to 500 μm were detected in seminal vesicles. Only late-sporogonic stages, i.e. pseudoplasmodia harbouring immature and/or mature myxospores, were observed and analysed. Scanning electron microscopy revealed that spores have smooth surface with exception of posterior valvular bulges, which possess numerous outwards opening internal canals. As revealed by both scanning and transmission electron microscopy, the canals are continuous invaginations of the outer spore surface. Myxospores of S. ranae are characterised by the presence of two uninucleate sporoplasms, bilayered polar capsules, S/H-shaped polar filaments in transversal section and multilayered polar filament eversion pole plugging complex. Ultrastructural observations are discussed in the context of available data for other species of Sphaerospora sensu stricto and apparent synchronisation of myxospore shedding with a brief aquatic breeding phase of vertebrate intermediate host is highlighted.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public