Effect of Fusarium autolysate on various immunologic and biologic indices of the state of the carp body]

The Fusarium autolysate has been studied for its effect on certain immunobiochemical, parasitological and fishery-biological characteristics of carp fingerlings in the experiment. It is shown that different methods of introduction and treatment of fish with the autolysate induce changes in titres of the compliment and the content of lysozyme in the blood serum of fish as well as growth of its body weight. Treatment of carp spawn before its incubation increases survivability of fish. It is shown advisable to apply the autolysate in food fishery.     

Phylogeography of Brachyplatystoma rousseauxii (Siluriformes - Pimelodidae) in the Amazon Basin offers preliminary evidence for the first case of "homing" for an Amazonian migratory catfish

The large pimelodid, Brachyplatystoma rousseauxii, is one of the two most important catfish species for the fisheries in the Amazon. It is captured by commercial and artisanal fishing fleets in at least five Amazonian countries, at fishing grounds more than 5000 km apart. Current evidence suggests a complex life cycle that includes the longest reproductive migration known for a freshwater fish species. Experimental fisheries have pointed to a decrease in yield in the Western Amazon. However, reliable information about the capture and status of this fishery resource is still nonexistent, and no study has ever addressed its genetic diversity. We sequenced the entire D-loop of 45 individuals of B. rousseauxii, fifteen from each of three different fishing locations along the main channel of the Solim?es-Amazonas System covering a distance of around 2200 km. Results of phylogenetic analyses, molecular diversity estimations, analysis of molecular variance, and nested clade analysis, together show that there is no genetic segregation associated with location in the main channel, as one would expect for a migratory species. However, the significant decrease found in genetic diversity towards the western part of the Amazon could be explained by a non-random choice of tributary to spawn. It is possible that the genetic diversity of the migrating schools decreases towards the west because portions of the species' genetic diversity are being "captured" by the different effluents, as the fish migrates to spawn in the headwaters. Like the salmon in North America, B. rousseauxii may be returning to their home tributary to spawn.     

High permissivity of the fish cell line SSN-1 for piscine nodaviruses.

Seventeen isolates of piscine nodavirus from larvae or juveniles of 13 marine fish species affected with viral nervous necrosis (VNN) were examined for their infectivity to a fish cell line SSN-1. Based on cytopathic effects (CPE) and virus antigen detection by fluorescent antibody technique (FAT) after incubation at 25 degrees C, the infectivity of these virus isolates was divided into 4 groups. Group 1, including 9 virus isolates from 4 species of grouper, 2 species of sea bass, barramundi, rock porgy, and Japanese flounder showed CPE characterized by rounded, granular cells with heavy cytoplasmic vacuoles within 3 d post-incubation (p.i.), and the monolayer partially or completely disintegrated over 3 to 6 d p.i. Scattered FAT-positive cells appeared at 3 h p.i. and spread through the cell sheet with an increasing fluorescence signal over 24 h p.i. Group 2, consisting of 3 virus isolates from striped jack, induced CPE with thin or rounded, granular, refractile cells without conspicuous vacuole formation, and extensive FAT-positive reaction was observed in a time course similar to that of Group 1. Cells inoculated with Group 3 (1 isolate from tiger puffer) developed no distinct CPE but viral infection was evidenced by localized FAT-positive cells. There were no FAT-positive cells in Group 4, which included 4 isolates from Japanese flounder, Pacific cod and Atlantic halibut. However, when incubation was performed at 20 degrees C, the SSN-1 cells inoculated with the Group 3 isolate showed CPE similar to that of Group 1 and extensive FAT-positive reaction. Evidence of virus proliferation at 20 degrees C was also obtained in Group 4 isolates. The virus titers in the infected fish varied from 10(11) to 10(16) tissue culture infectious dose (TCID50) g(-1) of fish. There is a good correlation between these infectivities to the SSN-1 cells and the coat protein gene genotypes of the isolates. The present results indicate that SSN-1 cells are useful for propagating and differentiating genotypic variants of piscine nodavirus.     

Reproduction and development of <Emphasis Type="Italic">Pholis picta</Emphasis> (Perciformes: Pholidae) and <Emphasis Type="Italic">Opisthocentrus zonope</Emphasis> (Stichaeidae)

In the Peter the Great Bay (the Sea of Japan), reproduction and embryonic larval development of Pholis picta and Opisthocentrus zonope are investigated. Both species spawn in November–December at the water temperature decreasing from 7.0 to 0.2°C. Fecundity of Pholis picta is 494–1228 eggs, and of Opisthocentrus zonope—368–1360 eggs. Both species lay eggs in empty shells of Gray mussel. Parent fish permanently stay in the shell but do not actively care for the eggs. Morphological changes in the process of embryogenesis are compared between the related species. Prolarvae and larvae are described for identification, with special attention to pigmentation. The spawning behavior of adult fish and behavior of prolarvae are described.     

Mycological aspects of a disease of young perch in Windermere

A disease of young perch in Windermere was investigated. In contrast to the case of U.D.N. infections of salmon and trout, a variety of fungi were obtained from the diseased fish. These reflected the spora present in the water at the same time to a large extent. An exception was Saprolegnia ferax , which did not grow on the fish and indicated that some degree of host specificity was involved. The Achyla isolates, both from the fish and from the water, were found to be heterothallic and male in reaction.     

Growth and reproductive performance of the Asian catfish Clarias macrocephalus (Gunther) fed artificial diets

Four natural ingredient diets similar in nutrient composition (crude protein = 42–44%; P/E ratio = 115–120 mg/kcal) but different in protein sources, were formulated and fed to hatchery-reared catfish to measure the relative performance of the catfish fed alternative broodstock diets. The control feed was a combination of fish-by-catch and commercial fish pellets. In trial I, growth of the catfish was slow over a 36-week period, but some fish became gravid. Diets 1, 2, and 3 and the control feed were tested in trial II. Growth of fish did not differ significantly (P > 0.05) and female fish in all treatments became gravid. For fish induced to spawn from April to August (1994), hatching rate showed significant differences among treatments (P < 0.05). Relative fecundity, fertilization and hatching rates, and production of 3-day-old larvae were significantly different among fish induced to spawn in November (1994) when another incubation setup was used. Among the diets, diets 2 and 3 best enhanced reproductive performance of the catfish.     

Variation in mycorrhizal performance in the epiphytic orchid <Emphasis Type="Italic">Tolumnia variegata in vitro</Emphasis>: the potential for natural selection

Symbiotic seed germination is a critical stage in orchid life histories. Natural selection may act to favor plants that efficiently use mycorrhizal fungi. However, the necessary conditions for natural selection – variation, heritability, and differences in fitness – have not been demonstrated for either orchid or fungus. With the epiphytic orchid Tolumnia variegata as a model system, we ask the following questions: (1) Do seeds from different individuals in a population differ in germination and seedling development in the presence of the same fungi? (2) Do different mycorrhizal fungi (Ceratobasidium spp.) differ in ability to stimulate seed germination and growth in T. variegata? And (3) are the Ceratobasidium isolates that best induce seed germination and seedling development more closely related to each other than to isolates that are less effective? We performed symbiotic seed germination experiments in vitro. The experiments were done using mycorrhizal fungi isolated from T. variegata; relationships among the fungi were inferred from nuclear ribosomal ITS sequences. We found significant variation for both symbiotic germination and seedling growth among biparental seed crops obtained from a population of T. variegata plants. Differences among Ceratobasidium fungi in seed germination were significant. The fungi that induced highest seed germination and seedling development belonged to two of four clades of Ceratobasidium. The two experiments show that there is potential for natural selection to act on orchid–fungus relationships. Given that orchids vary in performance, and that mycorrhizal fungi are not geographically distributed homogeneously, mycorrhizae may affect population size, distribution and evolution of orchids.     

Reproductive biology of ningu, <Emphasis Type="Italic">Labeo victorianus</Emphasis> (Pisces : Cyprinidae), in the Kagera and Sio Rivers,Uganda

Synopsis We investigated aspects of the reproductive biology of the cyprinid fish, Labeo victorianus, locally known as ningu, in the Kagera and Sio Rivers, Uganda. These rivers represent the last remaining refuges for this species within Uganda. L. victorianus is a highly fecund, potamodrometic fish that migrates upstream to spawn. Spawning is generally synchronised with the bimodal water level maxima observed within the rivers. There were, however, some deviations from this pattern. We caught sexually mature fish throughout the year in the Sio River, and noticed that spawing started before the second rainfall peak. Fish from the Kagera matured at significantly larger sizes than fish from the Sio River. Male and female fish, from both rivers, fed intensively during the non-breeding months accumulating significant fat reserves; a probable energy storage mechanism prior to their spawning migrations. The differences between the populations is probably a phenotypic response to differing abiotic factors such as river size, flow velocity and food availability.     

Prevalence and transmission of antimicrobial resistance among <Emphasis Type="Italic">Aeromonas</Emphasis> populations from a duckweed aquaculture based hospital sewage water recycling system in Bangladesh

In order to investigate the influence of a duckweed aquaculture based hospital sewage water recycling plant on the prevalence and dissemination of antibiotic resistance, we made use of an existing collection of 1,315 Aeromonas isolates that were previously typed by the biochemical fingerprinting PhP-AE system. In these treatment plant, hospital raw sewage water is first collected in a settlement pond (referred to as sewage water in this study) and is then transferred to a lagoon, where the duckweed (Lemnaceae) is grown (referred to as lagoon). The duckweed is harvested and used as feed for the fish in a separate pond (referred to as fish pond). From this collection, representatives of 288 PhP types were subjected to antibiotic susceptibility testing for eight antimicrobials by broth microdilution method. The overall resistance rates among Aeromonas isolates from the treatment plant were highest for ampicillin (87%) and erythromycin (79%) followed by cephalothin (58%), nalidixic acid (52%), streptomycin (51%), tetracycline (31%), chloramphenicol (13%) and gentamicin (8%). A significantly lower prevalence of antibiotic resistance was found in Aeromonas from environmental control water, patient stool samples, duckweed and fish compared to sewage water isolates. The prevalence of resistance in the sewage water was not significantly reduced compared to the lagoon water and fish pond. Throughout the treatment system, the frequencies of resistant strains were found to diminish during the sewage water purification process, i.e. in the lagoon where sewage water is used to grow the duckweed. However, the frequency of resistant strains again increased in the fish pond where sewage grown duckweed is used for aquaculture. Among the selected isolates, two multiresistant clonal groups of Aeromonas caviae HG4 were identified that exhibited indistinguishable PhP and amplified fragment length polymorphism fingerprints and shared a common plasmid of approximately 5 kb. Representatives of both groups were recovered from almost every part of the sewage treatment plant but not in the control ponds nor in human samples, which suggests that specific multiresistant Aeromonas clones are able to persist and spread throughout the entire purification process.     

Fungal culture of musculoskeletal tissue: what’s the point?

There have not been any studies that review the prevalence of fungal isolates using selective media from samples of banked musculoskeletal tissue retrieved from living and cadaveric donors. A total of 2,036 swab and 2,621 biopsy samples of musculoskeletal tissue from tissue banks were received from the 1st August 2008 till 31st December 2010. Routine culture for fungi using selective media with a prolonged incubation period failed to demonstrate a greater prevalence of fungal isolates than by using non-selective culture media alone. Using selective culture fungi were recovered from only two Sabouraud agar plates (0.1%) but not from non-selective media. During the same period fungi were isolated from three graft samples cultured in non-selective broth media only (0.1%). There was no correlation of fungal isolates from selective or non-selective media inoculated at the same time nor from multiple graft samples collected from the same donor supporting the possibility of an exogenous source for fungal isolates rather than an endogenous source.     

Latent infections of <Emphasis Type="Italic">Fomes fomentarius</Emphasis> in the xylem of European beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>)

Fungal colonisation originating from endophytic thalli in wood of healthy European beech trees (Fagus sylvatica) was studied. Fungi were isolated from wood immediately after felling and after incubation for 8, 16 and 24 weeks under two different drying regimes. Two media were used to isolate fungi: malt extract agar with and without thiabendazol. Thiabendazol was added to inhibit non-basidiomycetes. The two drying regimes had no influence on the species composition of the recovered mycobiota and the frequency of isolation of these species. Mycelia of basidiomycetes except Coniophora puteana emerged only from wood samples inoculated onto malt extract agar containing thiabendazol. Only a few isolates were obtained from freshly cut wood, but a great number of isolates was recovered already after eight weeks of wood incubation. Four taxa accounted for 88 % of the total number of isolates: Hypoxylon fragiforme, Trichoderma spp., and the basidio-mycetes Coniophora puteana and Fomes fomentarius. The latter had not been considered an endophyte before. The isolates of F. fomentarius were made exclusively from the stem and some large diameter branches, which are the locations of its basidiocarps on dying trees. Every isolate of F. fomentarius was genetically different as revealed by tests for somatic compatibility. Advantages of the presumed endophytic strategy of F. fomentarius are discussed. Microscopic investigations showed a great number of hyphae within the cell lumina of vessels and a distinct wood degradation already after eight weeks of wood incubation.     

DNA adduct formation by Fusarium culture extracts: lack of role of fusarin C

Fusarium fungi have been shown to infect corn and other crops worldwide, and have a significant impact on human health through loss of crops or contamination of food with mycotoxins. Isolates of Fusarium fungi from an area of South Africa with high incidence of esophageal cancer have been shown to induce esophageal and liver cancer in rats. Several isolates of Fusarium fungi were grown on corn to determine if genotoxic products were produced. We report the incubation of methanol extracts of Fusarium verticillioides cultures with DNA in the presence of rat liver fractions (S9) resulted in the formation of a unique DNA adduct that was detected by (32)P-postlabeling. Fusarin C was purified from cultures of Fusarium verticillioides RRC 415, and was not responsible for the formation of the DNA adduct. Treatment of the methanolic extracts with ultraviolet B radiation reduced the fusarin C content in the extract; however, this had no effect on the formation of the DNA adduct following incubation of the extract with DNA and S9. The unique DNA adduct was formed following the incubation of several Fusarium verticillioides isolates from the US and South Africa, while extracts of cultures of Fusarium graminearium and Fusarium sacchari isolates formed very little of the DNA adduct when incubated with DNA and S9. These data suggest that neither fusarin C nor any of its metabolites are responsible for formation of the DNA adduct, and that an unidentified compound is present in F. verticillioides cultures that forms a DNA adduct, and may be important in the etiology of human esophageal cancer.     

Characterization of ichthyocidal activity of Pfiesteria piscicida: dependence on the dinospore cell density

The ichthyocidal activity of Pfiesteria piscicida dinospores was examined in an aquarium bioassay format by exposing fish to either Pfiesteria-containing environmental sediments or clonal P. piscicida. The presence of Pfiesteria spp. and the complexity of the microbial assemblage in the bioassay were assessed by molecular approaches. Cell-free water from bioassays that yielded significant fish mortality failed to show ichthyocidal activity. Histopathological examination of moribund and dead fish failed to reveal the skin lesions reported elsewhere. Fish larvae within "cages" of variable mesh sizes were killed in those where the pore size exceeded that of Pfiesteria dinospores. In vitro exposure of fish larvae to clonal P. piscicida indicated that fish mortality was directly proportional to the dinospore cell density. Dinospores clustered around the mouth, eyes, and operculi, suggesting that fish health may be affected by their direct interaction with skin, gill epithelia, or mucous surfaces. Molecular fingerprinting revealed the presence of a very diverse microbial community of bacteria, protists, and fungi within bioassay aquaria containing environmental sediments. Some components of the microbial community were identified as potential fish pathogens, preventing the rigorous identification of Pfiesteria spp. as the only cause of fish death. In summary, our results strongly suggest (i) that this aquarium bioassay format, which has been extensively reported in the literature, is unsuitable to accurately assess the ichthyocidal activity of Pfiesteria spp. and (ii) that the ichthyocidal activity of Pfiesteria spp. is mostly due to direct interactions of the zoospores with fish skin and gill epithelia rather than to soluble factors.     

Long distance migration and marine habitation in the tropical Asian catfish, Pangasius krempfi

A synthesis of catch data from southern Laos and life-history information indicate that adult Pangasius krempfi , an important Asian catfish, migrates up the Mekong River from the South China Sea in Vietnam past Cambodia, arriving in southern Laos each year in May. Strontium concentrations in the otoliths of river-caught P. krempfi are, on average, three to four times higher than the levels of strontium in the otoliths of related freshwater species, indicating marine and estuary habitation for fish caught in southern Laos. Pangasius krempfi muscle tissue samples from the same fish also exhibit stable isotope (δ¹⁵N and δ¹³C) values characteristic of marine environments. The results of this investigation support the conclusion that P. krempfi is anadromous, spending a part of its life at sea and in the brackish water of the Mekong Delta before returning to spawn in fresh water. The fish travels at least 720 km to the Khone Falls in southern Laos, and possibly further. Spawning probably occurs in fresh water from June to August at which time young fish move down the Mekong River to the Mekong Delta. The data answer a previously unresolved question (the long-distance migratory behaviour of P. krempfi ) and have important implications for the management and conservation of Mekong River fishes.     

<Emphasis Type="Italic">Takifugu obscurus</Emphasis> is a euryhaline fugu species very close to <Emphasis Type="Italic">Takifugu rubripes</Emphasis> and suitable for studying osmoregulation

Background  

The genome sequence of the pufferfish Takifugu rubripes is an enormously useful tool in the molecular physiology of fish. Euryhaline fish that can survive both in freshwater (FW) and seawater (SW) are also very useful for studying fish physiology, especially osmoregulation. Recently we learned that there is a pufferfish, Takifugu obscurus, common name "mefugu" that migrates into FW to spawn. If T. obscurus is indeed a euryhaline fish and shares a high sequence homology with T. rubripes, it will become a superior animal model for studying the mechanism of osmoregulation. We have therefore determined its euryhalinity and phylogenetic relationship to the members of the Takifugu family.     

Oogenesis of paliya <Emphasis Type="Italic">Salvelinus alpinus</Emphasis> complex (Salmonidae) during its breeding under fish-farm conditions

A histological study of oogenesis of paliya Salvelinus alpinus complex (from larvae aged 3 weeks after hatching to the age of 3 years and 9 months) has been carried out. The fish was bred in tanks of the Federal Center of Fish Genetics and Selection (FCFGS, Ropsha, Leningrad oblast). Three-week-old larvae had primordial cells and gonia of the first orders in rudimentary gonads. Sex differentiation was completed and development of ovarian plates started in young fish aged 3.5 months. There were already previtellogenic oocytes in fish ovaries at this age. The morphology of the circumnuclear zone in previtellogenic oocytes of all stages, which appear as the age of the fish increases, as well as the morphology of oocytes of the period of trophoplasmatic growth, are described. In FCFGS conditions, paliya females aged 3 years and 9 months did not mature or oocytes degenerated in mature females. Only after a year, normal spawn was obtained from mature females.     

Water mold infections of freshwater fish: Recent advances

Various investigations have identified morphological and physiological differences among water mold isolates. There is some evidence that isolates taken from fish lesions are more infective for live fish and are more resistant to host defenses, compared to environmental isolates. Many other characteristics, including propagule retention on fish, propagule morphology, propagule response to nutrients, fungal isozyme patterns, and antigenic relatedness of fungal isolates, have been examined. However, the significance of these characteristics to pathogenicity is uncertain, either because the putative pathogenic marker does not consistently differentiate pathogenic from saprophytic isolates, or the adaptive significance of the marker is unclear. Water molds grow rapidly in dead tissue, yet do not easily cause disease in healthy, unstressed hosts. They are usually relegated to the skin and superficial muscle. The fact that they are common secondary invaders of wounds implies that in these instances there is a significant compromise of host defenses. Trauma, nutritional deficiencies, endocrine changes, and stressful water quality have been implicated. There may be major differences in how different fish species respond to such stresses. Both humoral and cellular defensive responses to invading water molds have been observed. The type of response may modulate the gross clinical signs of the resulting infection.     

The biological characteristics of micromycetes isolated from fish roe

The fungi Aspergillus fumigatus Fres., and Fusarium sporotrichiella Bilai were studied for their effect on certain biochemical indices of two-year carp and spawn of grass carp under laboratory conditions. The intraperitoneal introduction of A. fumigatus in a dose of 5 and 20 min conidia per individual to two-year carp decreased significantly the protein level in blood serum, the decrease being more considerable with the introduction of the smaller dose of fungal conidia. Joint incubation of the grass carp spawn and F. sporotrichiella induced changes in the protein level, amylolytic and phosphate (acid phosphatase) activity in spawn. In that case the time of the fungus action on grass carp spawn was a decisive factor. Activity of certain hydrolytic enzymes in mycelium and conidia of A. fumigatus and F. sporotrichiella was determined. The amylolytic activity was not revealed in the checked samples. The proteolytic activity was established in all samples of fungi and culture liquid, the highest level being observed in mycelia and conidia of A. fumigatus. The alkaline and acid phosphatase activity was found in F. sporotrichiella: the acid phosphatase activity was higher in mycelium, the acid phosphatase one in the fungus conidia. The problem on the A. fumigatus ability to produce extracellular enzymes is under discussion.     

Seabed photography,environmental assessment and evidence for deep-water trawling on the continental margin west of the Hebrides

Little is known about marine filamentous fungi and yeasts, almost nothing about their life and metabolism under deep sea conditions. Data on growth and metabolic activity give insight into the role of organisms in the marine habitat. Degradation studies on pollutants, such as polymeric thermoplasts, provide information about the self-cleaning capacity of a habitat. Therefore, recently isolated fungal strains from the deep sea and our newly developed methods and apparatus for investigation of fungi under simulated deep sea conditions were used to study fungal growth and degradation of a commercially produced thermoplastic polymer (poly--hydroxybutyric acid = PHB). Two deep sea isolates, a filamentous fungus (Aspergillus ustus) and one yeast (Rhodosporidium sphaerocarpum), and for comparison, two marine surface yeast isolates (Candida guilliermondii, Debaryomyces hansenii) and one terrestrial isolate of Aspergillus ustus were investigated. Growth (colony-forming units, dry weight), physiological parameters (oxygen saturation of the hydraulic fluid as oxygen reservoir, pH and consumption of total carbohydrate) and PHB degradation (clearing test: clearing of PHB-turbid agar medium; spectrophotometric test: PHB depolymerase activity) were followed after incubation in high-pressure autoclaves in artificial seawater medium at 27 °C and pressures of 0.1 MPa (= atmospheric pressure), 5 MPa, 10 MPa, 20 MPa, 30 MPa, 45 or 50 MPa and 100 MPa ( 10000 m water depth) for a maximum of 21 days (yeasts) and 28 days (filamentous fungi), respectively. Irrespective of the marine or terrestrial origin of the isolates, growth decreased with increasing pressure with a limit between 30 MPa and 50 MPa for filamentous fungi and yeasts. Metabolic activity (consumption of medium components) started to decrease from 20 MPa, ceasing at growth-limiting pressures. Under atmospheric conditions, all strains degraded PHB in solid medium, in liquid medium degradation was less and decreased further and/or was delayed with increasing hydrostatic pressure; beyond 30 MPa, no PHB degradation could be observed. In summary, it could be shown that growth, metabolism and degradation of pollutants such as PHB by marine fungal isolates was impaired with increasing pressure, showing one aspect of the reduced self-cleaning capacity of the deep sea habitat.Dedicated to Prof. Dr Jan Kohlmeyer, Morehead City, USA, on the occasion of his 70th anniversary     

Studies on the mycotic inhabitants ofCulex pipiens collected from fresh water ponds in Egypt

A total of 20 fungal species belonging to 10 genera were found to be associated with all stages ofCulex pipiens. Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger andPenicillium chrysogenum were the dominant fungi.Beauveria alba andPhoma herbarum. A well known facultative pathogen have been recorded. Most of fungal isolates (63.22%) showed a moderate growth on a synthetic medium containing partially purified chitin. The water extract of bothArtmesia cina andCleome droserifolia showed an inhibitive effect on the protein content and growth of some selected isolates. One ml dose of crude extract ofA. fumigatus killed 90% of the larvae after 192 hr incubation but 36% of the test larvae were killed by the same dose extracted fromP. chrysogenum at the same period of incubation.