Concurrent invaders--four exotic species of Monogenea now established on exotic freshwater fishes in Australia

Four species of exotic monogeneans are reported from five species of exotic freshwater fish in Australia: Gytrodactylus bullatarudis from Poecilia reticulata and Xiphophorus helleri in Queensland; Gyrodactylus macracanthus from Misgurnus anguillicaudatus in the Australian Capital Territory; Dactylogyrus extensus from Cyprinus carpio in the Australian Capital Territory; and Dactylogyrus anchoratus from Carassius auratus in the Australian Capital Territory. This is the first published record of described species of monogeneans of the genus Dactylogyrus or Gyrodactylus from Australia and the first report of parasites of M. anguillicaudatus in Australia. The establishment of exotic monogenean populations on Australian native fishes via host-switching is considered less likely than for other parasitic groups due to the generally high host-specificity of monogeneans, combined with the phylogenetic dissimilarity of native and exotic fishes. Similar establishments have occurred elsewhere, however, and the risk of these events increases with each new fish species introduction.     

Comparative analysis: a tool for studying monogenean ecology and evolution

The comparative approach has been used widely in evolutionary ecology during the last 10 years. In the first part of this study, taking monogeneans of Mediterranean marine fishes as an example, we highlight the pitfalls that may arise in interspecific studies. In the second part, the independent contrast method is used to control for phylogenetic effects in order to evaluate the determinants of monogenean species richness and their specificity. Our results show the importance of controlling data for both host sample size and phylogeny to avoid confounding effects. Thereafter, taking into account both sampling effort and phylogenetic effects, our results show that host size is the main factor affecting monogenean species richness and specificity.     

Pharmacokinetic MRI for assessment of malignant glioma response to stereotactic radiotherapy: initial results

The parasites of the red rockfish Sebastes capensis off northern Chile are described quantitatively for the first time and compared with those of congeneric species of the Northern Hemisphere as well as of other Chilean marine fishes. Sixteen species were recorded, including 8 ectoparasites (2 copepods, 2 isopods, 1 turbellarian, and 3 monogeneans) and 8 endoparasites (2 acanthocephalans, 3 digeneans, and 3 nematodes). The ectoparasites Lepeophtheirus chilensis and Caligus cheilodactylus, and the endoparasites Pseudopecoelus sp. and Corynosoma sp. were predominant. Eighty percent of the fishes harbored 3-6 parasite species. Four parasite genera new to the genus Sebastes were found in S. capensis, which also shares several parasite genera with its congeneric species from other geographic areas. However, in contrast to its congeners, S. capensis exhibits a lower helminth species richness, although when all the metazoan fauna is considered the species number and diversity are similar. When compared with other demersal fishes of the Chilean coast, S. capensis shows a high number of species and high parasite abundance. Diphtherostomum sp. and Gnathia sp. are new generic records for the parasite fauna of Chilean coast fishes and the finding of Paramicrocotyle sp., Neobenedenia melleni, and Interniloculus chilensis in this study represents a new geographical record for these parasites.     

Diversity of monogeneans in Southeast Asia

The diversity of monogeneans from Southeast Asia was examined using information from the literature to show their diversity at different taxonomic (subclass, family, genera, species) levels. Knowledge of monogeneans is still incomplete in Southeast Asia and the present numbers of monogeneans are likely an underestimate of what is present on/in aquatic organisms in the region, since so few hosts have been examined. An estimate of the possible numbers of monogeneans that could be present on/in fishes and turtles in Peninsular Malaysia indicates that only 8% of the monogeneans are presently known. Analysis of the available data on monogenean diversity (or species richness) at different taxonomic levels will provide useful information on their distribution patterns. There is an uneven distribution of investigations on this topic and Malayan fauna is considered to be representative of the Southeast Asian fauna. Southeast Asian (Sundaland) monogeneans are related (at the generic level) to the monogenean fauna of South China, India and Africa.     

Chromosome region 8p11-p21: refined mapping and molecular alterations in breast cancer

This review illustrates the use of experimental approaches combined with microscopy to study the biology of monogenean parasites. Studies of feeding, development, reproduction, and systematics have been based on gyrodactylids, flatworms infecting teleost fishes. In a contrasting system involving an amphibian host in a desert environment, analysis of adaptations to extreme conditions has focused on Pseudodiplorchis americanus. The unusual reproductive strategies, particularly the interactions between mother and offspring, are highlighted for both monogeneans. Species of Gyrodactylus are viviparous, maintaining up to three generations of embryos simultaneously in utero, and many of their reproductive specializations are related to progenesis. Embryo nutrition takes place via a metabolically-active syncytial uterine lining that has close association with the parental gut. Microscopy has also proved an essential adjunct to molecular studies of speciation and host specificity. P. americanus is ovoviviparous and the adaptations for embryo maintenance are unique. The primary keratin-type eggshell is replaced by a flexible secondary elastin capsule produced by the uterus; parental nutrients are transferred through cytoplasmic connections to the developing embryo. TEM has demonstrated unique adaptations of P. americanus to its micro-environments, including secretion of tegumental vesicles that provide protection from digestive enzymes during migration through the host gut. This paper highlights the potential of monogeneans for studies of fundamental biological principles.     

Haplorchoides Chen, 1949 (Haplorchinae: Heterophyidae) in freshwater fishes

Two metacercariae of Haplorchoides, recorded in the fingerlings of over a dozen species of freshwater fishes, are described and illustrated. Ovigerous flukes were recovered from older specimens of two species of fishes procured from the same locality. Comparison of taxonomic characters of the juveniles and adults suggests that they are conspecific. The metacercariae and adults are assigned to two new species, Haplorchoides pearsoni and H. Mehrai. The observations, presented herein, necessitated a review of the species named under this genus and a revision of the generic diagnosis. The reports on fish intermediaries of H. attenatus have been enlarged.     

A revision of Neoheterocotyle (Monogenea:Monocotylidae) with descriptions of the larvae of N. rhinobatis and N. rhynchobatis from Heron Island, Great Barrier Reef, Australia

Rhinobatos typus and Rhynchobatus djiddensis were collected from Heron Island, Australia and examined for monocotylid parasites. Specimens of Neoheterocotyle rhinobatidis (Young, 1967) Chisholm, 1994 and N. rhynchobatis (Tripathi, 1959) Chisholm, 1994 were collected from the gills of Rhinobatos typus. This represents both a new host and new locality record for N. rhynchobatis. Neoheterocotyle bychowskyi (Timofeeva, 1981) Chisholm, 1994, N. nagibinae (Timofeeva, 1981) Chisholm, 1994 and N. rhinobatis (Pillai & Pillai, 1976) n. comb. were identified from the gills of Rhynchobatus djiddensis from Australia and are all new locality records. We consider N. djiddensis (Pillai & Pillai, 1976) n. comb. a species inquirenda and synonymise N. trilobata Timofeeva, 1981 with N. rhinobatis. Therefore, there are 7 valid species in the genus, including N. bychowskyi, N. forficata, N. inpristi, N. nagibinae, N. rhinobatidis, N. rhinobatis and N. rhynchobatis. The larvae of N. rhinobatis and N. rhynchobatis are described and the anterior glands of the larvae are related to those of the adults. The development of the male copulatory organ of N. rhinobatidis is described. Host-specificity and geographic range of the genus are also discussed and a key to species is provided.     

Mitochondrial ND1 gene sequences used to identify echinostome isolates from Australia and New Zealand

Echinostomes were collected in Australia and New Zealand as cercariae, metacercariae or adults. Using DNA sequences from the mitochondrial ND1 gene Echinostoma revolutum and Echinostoma paraensei were discovered in Australia. The presence of a further five, as yet unidentified, echinostome species was inferred in Northern Australia and a further isolate, closely allied to E. revolutum, occurs in New Zealand. ND1 sequences of species within the genus diverge from each other by 9.6-30.8%. Sequence divergence levels among strains within a single species are 0-3.6%. The phylogenetic tree produced from the Australasian isolates, in addition to species described previously, identifies the 37-collar-spine species as a well supported monophyletic group. The five unidentified Australian species cluster away from the 37-collar-spine group. These unidentified species appear to divide further into > 37-collar-spine and < 37-collar-spine clusters. Three strains of E. revolutum, collected as metacercariae from snails, were identified from two ponds located 6 km apart. Two of these strains may be cycling through a planorbid snail, Glyptophysa sp., as first intermediate host; however, this hypothesis could not be confirmed as specimens could not be obtained to match sequences between larvae and adults.     

Association of marine archaea with the digestive tracts of two marine fish species

Recent studies have shown that archaea which were always thought to live under strict anoxic or extreme environmental conditions are also present in cold, oxygenated seawater, soils, the digestive tract of a holothurian deep-sea-deposit feeder, and a marine sponge. In this study, we show, by using PCR-mediated screening in other marine eukaryotes, that marine archaea are also present in the digestive tracts of flounder and grey mullet, two fish species common in the North Sea, in fecal samples of flounder, and in suspended particulate matter of the North Sea water column. No marine archaea could be detected in the digestive tracts of mussels or the fecal pellets of a copepod species. The archaeal 16S ribosomal DNA clone libraries of feces of flounder and the contents of the digestive tracts of grey mullet and flounder were dominated by group II marine archaea. The marine archaeal clones derived from flounder and grey mullet digestive tracts and feces formed a distinct cluster within the group II marine archaea, with 76.7 to 89. 8% similarity to previously described group II clones. Fingerprinting of the archaeal community of flounder digestive tract contents and feces by terminal restriction fragment length polymorphism of archaeal 16S rRNA genes after restriction with HhaI showed a dominant fragment at 249 bp, which is likely to be derived from group II marine archaea. Clones of marine archaea that were closely related to the fish-associated marine archaea clones were obtained from suspended particulate matter of the water column at two stations in the North Sea. Terminal restriction fragment length polymorphism fingerprinting of the archaeal community present in suspended particulate matter showed the same fragment pattern as was found for the archaeal community of the flounder digestive tract contents and feces. These data demonstrate that marine archaea are present in the digestive tracts and feces of very common marine fish. It is possible that the marine archaea associated with the digestive tracts of marine fish are liberated into the water column through the feces and subsequently contribute to the marine archaeal community of suspended particulate matter.     

Attachment and detachment of the anterior adhesive pads of the monogenean (platyhelminth) parasite Entobdella soleae from the skin of the common sole (Solea solea)

By preserving specimens of the monogenean (platyhelminth) parasite Entobdella soleae at intervals during locomotion and processing these parasites for transmission and scanning electron microscopy, evidence was found to suggest that adhesion of the anterior pads to the skin of the host, the sole Solea solea, is brought about by interaction between the two kinds of glandular secretion supplied to the pads. It is suggested that the specialised pad tegument through which the gland cell ducts pass may be instrumental in severing the adhesive bond by dissolving the cement immediately adjacent to this tegumental surface.     

Experimental study on 5-FU intraperitoneal injection for liver metastasis

It is estimated that Australia is home to more than 1 million species, less than 15% of which have been described. No estimate is given for parasites, but brief speculation on the potential is presented. The Commonwealth Government has a clear role in funding biosystematic research in Australia in support of its Natural Heritage Trust programmes, the National Biodiversity Strategy and its responsibilities under the Biodiversity Convention, and in order to maintain adequate taxonomic capacity. As a Government programme of Environment Australia, the Australian Biological Resources Study has disbursed around A$12 million towards taxonomic and biogeographic research on animals and Protozoa. Approximately 10% of this amount has gone towards parasitology. With funding for the Study being in a somewhat parlous state, it is argued that priorities for research funding need to focus clearly on issues of national significance as expressed in Government policies, strategies and environment programmes. In addition to scientific merit, research questions and projected outputs in project applications for funding should be justified in terms of meeting the needs of end users in conservation management, primary industry, and the wider biological research community.     

Computer identification of Escherichia coli rRNA gene restriction patterns

Hydropic vacuolation (HydVac) of biliary epithelial cells and hepatocytes is described for 3 species of U.S. West Coast bottom fishes. Risk assessment analyses are also conducted to determine if the prevalence of this lesion increases in association with contaminant exposure and site of capture. The morphology of HydVac in starry flounder Platichthys stellatus, white croaker Genyonemus lineatus and rock sole Lepidopsetta bilineata was similar to that described in winter flounder Pleuronectes americanus from the U.S. Atlantic Coast, especially in that HydVac most commonly affected biliary epithelial cells. Hydropic vacuolation was the most prevalent liver lesion in starry flounder and white croaker captured from contaminated environments. Risk assessment analyses confirmed that the relative risk for HydVac increased with the presence of aromatic and chlorinated hydrocarbons in sediment, fish bile, and fish liver for these species. Hydropic vacuolation also frequently occurred in rock sole, but the lesion showed no clear association with contaminant exposure in this species. The types of liver lesions that were useful biomarkers of contaminant effects in fish depended on the species and this factor must be taken into account when evaluating histopathological biomarkers of response to contaminant exposure.     

Biodiversity of parasites in a freshwater environment with respect to pollution: metazoan parasites of chub (Leuciscus cephalus L.) as a model for statistical evaluation

This paper represents an attempt to evaluate the environmental indicative potential of the biodiversity of monogenean parasites using hierarchically structured species-abundance data. A logical set of statistical methods integrating standard diversity indices, a novel approach to quantitative analysis of cumulative species-abundance curves and species-abundance models was applied for this purpose. Applicability of biodiversity measures was demonstrated using experimental data from a 1-year study on the ecology of metazoan parasites of chub (Leuciscus cephalus) in one polluted and one control site in the Morava river, Czech Republic. Analyses at the component community level revealed a significant decrease in the number of parasite species with a more equal distribution of their abundances in the polluted site compared with the control site. In order to reach a better understanding of the changes, diversity of Monogenea as a dominant part of the community was further examined within categories of species created according to: (1) specificity of infection (specialists and generalists), (2) monogenean genera (Dactylogyrus, Gyrodactylus and Paradiplozoon) and (3) inhabited guilds (skin + fins, gills). Assemblages of specialists in the polluted site exhibited a significantly reduced species richness and unequal distribution of abundances. The opposite pattern was observed in the case of generalists. The influence of pollution was also reflected by the distribution of species abundances within communities of Dactylogyrus and Paradiplozoon, while no significant shift was identified in the genus Gyrodactylus.     

Life cycle, host restriction and longevity of Babesiosoma mariae HOARE, 1930 (Apicomplexa: Dactylosomatidae)

Morphometric and morphological observations on B. mariae in an experimentally infected fish (using the leech vector Batracobdeloides tricarinata for the first time) revealed that three successive types of merogonic cycles occurred within the fish erythrocytes. The third cycle produced merozoites destined to become gamonts. The gamonts were somewhat larger than merogonic stages and comprised the majority of the parasitic stages during parasitaemia for up to 7 months. In the leech crop gamonts released from the fish blood became associated in syzygy and fused. The formed zygote underwent sporogony within the gut tissues and up to 8 sporozoites budded simultaneously from the periphery of an irregularly shaped oocyst. The sporozoites underwent merogony typical as that of erythrocytic merogony mainly in the salivary tissues. The merozoites either initiated a further cycle of merogony or moved towards the proboscis. The babesiosomes survived in the leech over a period of 9 months involving 7 meals after the initial meal provided the fasting period did not exceed 60-90 days. Survival was attributed to residual stages in the salivary glands. Cross transmission experiments between fishes via B. tricarinata revealed that the fish babesiosomes were not host specific. Previously described African fresh water fish dactylosomatids were indistinguishable from each other and on the basis of the current results, they are regarded as a single species Babesiosoma mariae.     

Preliminary validation of the MMPI-A for a male delinquent sample: an investigation of clinical correlates and discriminant validity

Bacterial strains of Aeromonas salmonicida included in the recognized subsp. acromogenes, subsp. masoucida, and subsp. smithia in addition to the large number of strains not included in any of the described subspecies are referred to as atypical A. salmonicida. The atypical strains form a very heterogeneous group with respect to biochemical characteristics, growth conditions, and production of extracellular proteasess. Consequently, the present taxonomy of the species A. salmonicida is rather ambiguous. Atypical A. salmonicida has been isolated from a wide range of cultivated and wild fish species, non-salmonids as well as salmonids, inhabiting fresh water, brackish water and marine environments in northern and central Europe, South Africa, North America, Japan and Australia. In non-salmonid fish species, infections with atypical strains often manifest themselves as superficial skin ulcerations. The best known diseases associated with atypical A. salmonicida are carp Cyprinus carpio erythrodermatitis, goldfish Carassius auratus ulcer disease, and ulcer disease of flounder Platichthys flesus, but atypical strains are apparently involved in more disease outbreaks than previously suspected. Macroscopical and microscopical studies of ulcerated fish indicate internal organs are infrequently invaded by atypical A. salmonicida. This view is supported by the fact that atypical strains are irregularly isolated from visceral organs of ulcerated fish. High mortality caused by atypical A. salmonicida has been observed in populations of wild non-salmonids and farmed salmonids, although the association between the mortality in the wild fish stocks and atypical A. salmonicida has not always been properly assessed. In injection experiments the pathogenicity of the atypical strains examined showed large variation. An extacellular A-layer has been detected in different atypical strains, but virulence mechanisms different from those described for (typical) A. salmonicida subsp. salmonicida, for example an extracellular metallo-protease and a different iron utilization mechanism, have been described. Limited information is available about the ecology, spread and survival of atypical strains in water. The commonly used therapeutic methods for the control of diseases in farmed fish caused by atypical A. salmonicida are generally effective against the atypical strains. Resistance to different antibiotics and transferable plasmid encoding multiple drug resistance have been observed in atpical A. salmonicida. Studies aimed at producing a vaccine against atypical strains are in progress.     

Heavy metals concentrations in acanthocephalans parasites compared to their fish host

A number of authors have demonstrated that heavy metal concentrations in intestinal Helminths are higher than those found in the tissues of their final hosts. In this work, Pb and Cr concentrations in the Acanthocephalan Acanthocephalus anguillae were measured by means of electrothermal atomic absorption spectrometry. The metal concentrations measured in the whole body of Acanthocephalans were compared to those in the liver of their fish hosts (Leuciscus cephalus) sampled in the Lambro river (Northern Italy). The results show higher concentrations of Pb and Cr in the parasites, respectively approximately 200 times and approximately 60 times higher than that of the host liver. These results corroborate the usefulness of parasites in the monitoring of biologically available metal concentrations in aquatic ecosystems that are non severely polluted.     

Electron microscopic investigation of the leishmaniasis cutanea. I. Leishmania tropica in the tissue (author''s transl)

On two patients suffering from Leishmaniasis cutanea from the old world florid and later a residual lesion could be removed for electron-mircroscopic examination, and the following was found: 1. A pseudocarcinomatous follicular epidermal proliferation in the florid lesion. 2. Macrophages with one to three Leishmania cells can be proved in histiocytes nests. The parasites are not always clearly surrounded by host cell membrane. 3. The endocellular Leishmania cells have a ciliary system which is open on the outside. It is, therefore, correct to speak of a cryptomastigotic shape of the flagellum. The kinetoplast shows direct transition to mitochondria. The number of periplast fibrillae or tubuli amounted to 95-97 which is less than in other types of Leishmania. Yet no further morphological distinctive feature between Leishmania tropica and the other types is discernible when a comparison with the pertinent literature is made. 4. No parasites to be considered virulent were found now in the late residual focus of previously secured cutaneous Leishmaniasis. The macrophages, on the other hand, contained big vacuoles with lamellar residual substances. These are regarded as rests of the parasites.     

Nonmanipulative parasites in manipulated hosts: 'hitch-hikers' or simply 'lucky passengers'?

Manipulation of intermediate host behavior to favor parasitic transmission has been demonstrated in a wide of range of parasitic taxa. Recent advances in parasitology have suggested that nonmanipulative parasite species can obtain a high probability of transmission simply by infecting hosts already manipulated ('hitch-hiker' parasites). In this study, from a field collection of Gammarus aequicauda (Amphipoda, second intermediate host), we analyzed the ecological association between the manipulative trematode Microphallus papillorobustus and the 2 nonmanipulative trematodes Microphallus hoffmanni and Levinseniella tridigitata. Although these 2 nonmanipulative parasites should be a priori advantaged when infecting manipulated gammarids, there was no significant ecological association between parasite species. We discuss the possible reasons why these 2 nonmanipulative parasites are only 'lucky passengers' rather than 'hitch-hikers.'     

Dangerous marine animals

Tales of dangerous marine animals have flourished, entwining history, legend and imagination. Man is now demonstrating his remarkable adaptability in returning to the aquatic environment, from which he had his origins, and factual knowledge of marine creatures is surplanting mystery, folklore and fear. There is still cause to fear certain aspects of the underwater world, and the one aspect that still holds sway over public interest is that of dangerous marine animals. There is little justification for this top priority. The kelp beds of San Diego will claim more diving victims than all the marine animals around the United States of America. The cold seas off the English coastline, the tidal currents of Hawaii and the multitude of drowning accidents in water caves of Florida and Australia belittle the relatively few fatalities caused by marine animals. Nevertheless, the latter do cause injury and death, especially in the tropical, subtropical and temperate regions. The Indo-Pacific area seems particularly well endowed with a variety of potentially lethal species, and some of these will be dealt with in this paper.     

Levels of chlordane compounds in fish muscle, -meal, -oil and -feed

Cis-, trans-, oxychlordane and trans-nonachlor were determined in the edible part of more than 140 fish samples of 15 different species and in fish meal, -oil and fish feed. The investigated fish included most of the important fish species consumed in Germany. Highest concentrations were found in muscle of marine fish with high or moderate fat content, but also in eel and farmed salmon. Marine fish with low fat content contained only traces of chlordane in the muscle tissue. A relationship between fishing ground and levels of chlordane could not be established. Contamination level of herring was related to the age (length) of the fish. Data are also given for contamination levels of fish meal, -oil and -feed.