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2. Advances in the knowledge of amphizoic amoebae infecting fish

Creator:
Dyková, Iva and Lom, Jiří
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
amphizoic amoebae, fish hosts, Acanthamoeba, Cochliopodium, Filamoeba, Naegleria, Neoparamoeba, Nuclearia, Platyamoeba, Thecamoeba, Vannella, and Vexillifera
Language:
English
Description:
Free-living amoebae infecting freshwater and marine fish include those described thus far as agents of fish diseases, associated with other disease conditions and isolated from organs of asymptomatic fish. This survey is based on information from the literature as well as on our own data on strains isolated from freshwater and marine fish. Evidence is provided for diverse fish-infecting amphizoic amoebae. Recent progress in the understanding of the biology of Neoparamoeba spp., agents responsible for significant direct losses in Atlantic salmon and turbot industry, is presented. Specific requirements of diagnostic procedures detecting amoebic infections in fish and taxonomic criteria available for generic and species determination of amphizoic amoebae are analysed. The limits of morphological and non-morphological approaches in species determination are exemplified by Neoparamoeba, Vannella and Platyamoeba spp., which are the most common amoebae isolated from fish gills, Acanthamoeba and Naegleria spp. isolated from various organs of freshwater fish, and by other unique fish isolates of the genera Nuclearia, Thecamoeba and Filamoeba. Advances in molecular characterisation of SSU rRNA genes and phylogenetic analyses based on their sequences are summarised. Attention is particularly given to specific diagnostic tools for fish-infecting amphizoic amoebae and ways for their further development.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Didymium-like myxogastrids (class Mycetozoa) as endocommensals of sea urchins (Sphaerechinus granularis)

Creator:
Dyková, Iva, Lom, Jiří, Dvořáková, Helena, Pecková, Hana, and Fiala, Ivan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Didymium-like myxogastrids, Myxogastrea, sea-urchin amoeba strains, SSU rDNA, flagellar apparatus, and phylogeny
Language:
English
Description:
This paper sums up the results of light microscopical, ultrastructural and molecular studies of five strains of amoeboid organisms isolated as endocommensals from coelomic fluid of sea urchins, Sphaerechinus granularis (Lamarck), collected in the Adriatic Sea. The organisms are reported as Didymium-like myxogastrids. Of the life-cycle stages, the attached amoeboids, flagellated trophozoites, cysts and biflagellated swarmers are described. Formation of fruiting bodies was not observed. Although phylogenetic analyses of SSU rDNA sequences indicated a close relationship with Hyperamoeba dachnaya, our sea-urchin strains have not been assigned to the genus Hyperamoeba Alexeieff, 1923. The presence of either one or two flagella reported in phylogenetically closely related organisms and mutually distant phylogenetic positions of strains declared as representatives of the genus Hyperamoeba justify our approach. Data obtained in this study may be useful in future analyses of relationships of the genera Didymium, Hyperamoeba, Physarum and Pseudodidymium as well as in higher-order phylogeny of Myxogastrea.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

8. Microsporidian xenomas in fish seen in wider perspective

Creator:
Lom, Jiří and Dyková, Iva
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
fish microsporidia, xenoma, life cycles, and cell pathology
Language:
English
Description:
The history of understanding xenoparasitic complexes or xenomas provoked in the host cell by various protists and especially by microsporidia is outlined. Microsporidia have been known to produce xenomas in oligochaetes (e.g., genera Bacillidium, Burkea, Hrabyeia, Jirovecia, species of the collective group Microsporidium), crustaceans (e.g., Abelspora, Mrazekia), insects (e.g., Polydispyrenia, Thelohania) and poikilothermic vertebrates, mostly fish (Alloglugea, Amazonspora, Glugea, Ichthyosporidium, Loma, Microfilum, Microgemma, Neonosemoides, Pseudoloma, Spraguea, Tetramicra). An overview of characters of xenomas caused by species of these genera is presented. The study of microsporidia causing xenomas in fish offers an insight into cell pathology and is of interest since many of these species are important agents of diseases in commercial fish. Xenomas produced from a few types of target cell display a complete change of organisation of the host cell and differ, according to the agent, in their structure. Recent data show that proliferation of the parasite may have already started in the cells transporting the parasites to the final site of xenoma formation. However, these are preliminary revelations and most of the facets of the life cycle are still to be clarified. Curiously, xenoma-forming microsporidia do not seem to be strictly host specific. The salient features of fish microsporidian xenomas are discussed, such as role of the xenoma, whether its features are host- or microsporidium-dependent, development and demise of the xenoma in the course of time, and host reaction phenomena. The need of further research is emphasised.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

9. Morphology and ultrastructure of Sphaeromyxa noblei sp. n. (Myxozoa), parasite of Heteroclinus whiteleggii (Pisces) from Australian New South Wales coast

Creator:
Lom, Jiří
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Sphaeromyxa noblei sp. n., ultrastructure, Myxosporea, and Heteroclinus whiteleggii
Language:
English
Description:
A new species, Sphaeromyxa noblei sp. n., is described from Heteroclinus whiteleggii (Perciformes: Clinidae), a marine fish from the coast of New South Wales in Australia. This raises the number of Sphaeromyxa species to 38; their list is presented. The species is characterised by a layer of branched glycostyles, which is about 2.4 µm thick and is a feature rather unique in Myxosporea. Pansporoblasts form one or two spores. The study of ultrastructure of this species and of those described to date result in recognition of a combination of patterns characterising the genus: plasmodia have marked surface projections, the endoplasm is full of vacuoles larger than in any other myxosporean genus, and contains a special kind of cells, the lobocytes. Sections through polar capsule reveal different appearance of subsequent stretches of the polar filament unlike in other Myxosporea.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

10. Myxozoan genera: definition and notes on taxonomy, life-cycle terminology and pathogenic species

Creator:
Lom, Jiří and Dyková, Iva
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Myxozoa, definition of genera, taxonomy, terminology, phylogeny, and pathogenic species
Language:
English
Description:
A list of myxozoan genera is presented in the current taxonomical scheme. These genera are defined; their type species and most important pathogens along with their hosts are listed. Simultaneously, definitions of actinospore stages representing sexual stages of the myxosporean life cycle are given; altogether, 17 actinospore collective groups with 180 types have been described. Life cycles of the two classes of the phylum Myxozoa, Malacosporea and Myxosporea, are briefly outlined with specification of the appropriate terms. Up to now, 4 malacosporean and 2,180 myxosporean species assigned to a total of 62 genera, have been established. The surviving classification of myxosporeans, based on spore morphology, is discussed in the context of the still fragmentary data resulting from SSU rDNA sequence analyses. The main task for the future is a rigorous, detailed morphological description combined with molecular techniques in establishment of new species and in revision of the existing ones. Establishment of a classification acceptable from morphological, biological and phylogenetical viewpoints is necessary.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public