Genomic organization and sequence of the mud loach (Misgurnus mizolepis) growth hormone gene: a comparative analysis of teleost growth hormone genes. (1/72)

The mud loach (Misgurnus mizolepis) growth hormone (GH) gene was cloned and a comparative analysis on its genomic organization was performed. Based on Southern analysis using various kinds of restriction endonucleases, the GH gene proved to exist as a single-copy gene in the mud loach. The complete nucleotide sequences of a 5.1 kb SacI/EcoRI genomic fragment containing the mud loach GH gene and its 5' flanking sequences as well as a mud loach GH cDNA obtained by rapid amplification of a reverse transcriptase-PCR have been determined. The GH gene spans 2.0 kb from the start codon to the polyadenylation signal, and contains five exons and four introns similar to those of carps and mammals. The evolutionary relation of the mud loach GH gene, inferred by comparative analyses of gene structures and sequences in each exon and intron of representative teleost GH genes, reflects the major phylogenetic groupings of teleost.  (+info)

Haff disease: from the Baltic Sea to the U.S. shore. (2/72)

Haff disease, identified in Europe in 1924, is unexplained rhabdomyolysis in a person who ate fish in the 24 hours before onset of illness. We describe a series of six U.S. patients from 1997 and report new epidemiologic and etiologic aspects. Although Haff disease is traditionally an epidemic foodborne illness, these six cases occurred in two clusters and as one sporadic case.  (+info)

Isolation of a lethal rhabdovirus from the cultured Chinese sucker Myxocyprinus asiaticus. (3/72)

A rhabdovirus was found to be associated with a lethal hemorrhagic disease in the cultured Chinese sucker Myxocyprinus asiaticus Bleeker. The rhabdovirus was amplified and isolated from the infected GCO (grass carp ovary) cells. In ultrathin sections of liver cells from the diseased fish, the virus particles exhibited the characteristic bacilliform morphology, and budded through vesicle membranes of the infected cells. The isolated rhabdovirus particles were found to have a bacilliform morphology with 2 rounded ends rather than a typical flat base. The virus particles were measured and ranged in size from 150 to 200 nm in length and 50 to 60 nm in diameter. Most other characteristics, including their size, extensive virus infectivity to fish cell lines, strong cytopathogenic effects, stability at high temperatures, vesicle formation in infected cells, structure protein electrophoretic patterns and the presence of an RNA genome, very closely resembled those of other fish rhabdoviruses. At present it is not known if this is a novel virus species or if it is an isolate of a known fish rhabdovirus. Until a confirmed identification can be made, we will temporarily refer to this virus as Chinese sucker rhabdovirus (CSRV).  (+info)

Fish shoal composition: mechanisms and constraints. (4/72)

Observations were made on three fish species (banded killifish (Fundulus diaphanus), golden shiner (Notemigonus crysoleucas) and white sucker (Catostomus commersoni)) in a temperate lake (New Brunswick, Canada) in order to investigate the relationship between shoal choice behaviour of individual fishes and shoal composition. Encounters between shoals were observed to take place every 1.1 min per shoal and an encounter lasted 3.7 s on average. The duration of shoal encounters was influenced by shoal size but not by differences between shoals in either body length or species. Conversely, the outcome of shoal encounters (i.e. ences between shoals in either body length or species. Conversely, the outcome of shoal encounters (i.e. whether or not an individual changes shoal) was influenced by body length and species differences but not by shoal size. Together, these results suggest that encounter duration itself is unlikely to have an important influence on encounter outcome. The collection of ten entire fish shoals showed that they were assorted by species and body length. A simulation model demonstrated that individual shoal choice behaviour alone could account for the generation and maintenance of the observed levels of size assortedness of shoals without invoking the existence of other sorting mechanisms such as differential swimming speeds. However, the generation of species assortedness was not predicted by the model. Furthermore, our data suggest that fish density acts as a constraint on shoal choice, influencing both shoal size and composition. This work has implications for studies on information transfer and reciprocal altruism within populations.  (+info)

Preferential interaction of loach DNA polymerase delta with DNA duplexes containing single-stranded gaps. (5/72)

We studied the interaction of DNA polymerase delta (pol delta) purified from the eggs of the teleost fish Misgurnus fossilis (loach) with DNA duplexes containing single-stranded gaps of 1-13 nucleotides (nt). In the absence of processivity factors (PCNA, RF-C, and ATP), pol delta elongated primers on single-stranded DNA templates in a distributive manner. However, the enzyme was capable of processive synthesis by filling gaps of 5-9 nt in DNA duplexes. These data suggest that, upon filling a small gap, pol delta interacts with the 5'-terminus downstream of the gap as well as with the 3'-terminus of the primer. Interaction of pol delta with the proximal 5'-terminus restricting the gap was confirmed by electrophoretic mobility shift assay. Analysis of the enzyme binding to DNA duplexes containing gaps of various sizes showed a much higher affinity of pol delta for duplexes with gaps of about 10 nt than for DNA substrates with primers annealed to single-stranded templates. The most efficient pol delta binding was observed in experiments with DNA substrates containing unpaired 3'-tails in primers. The data obtained suggest that DNA molecules with small gaps and single-stranded tails may serve as substrates for direct action of pol delta in the course of DNA repair.  (+info)

Identification and ultrastructural characterization of a novel virus from fish. (6/72)

During routine investigations on fish, a virus (isolate DF 24/00) with novel morphological features and hitherto undescribed morphogenesis was isolated from a white bream (Blicca bjoerkna L.; Teleostei, order Cypriniformes). Cell-free virions consist of a rod-shaped nucleocapsid (120-150x19-22 nm) similar to that seen in baculoviruses. The virion has a bacilliform shape (170-200x75-88 nm) reminiscent of rhabdoviruses with an envelope containing coronavirus-like spikes (20-25 nm). DF 24/00 replicated well in various fish cell lines. Inhibitor studies with 5-iodo-2'-deoxyuridine indicated that the viral genome consists of RNA and chloroform sensitivity correlated with ultrastructural demonstration of enveloped virions. The buoyant density of the virus determined in sucrose was 1.17-1.19 g/ml. Preliminary biochemical characterization revealed the presence of six antigenic glycoproteins, three of which contain sugars with concanavalin-A specificity. Ultrastructurally, morphogenesis of virus progeny was detected only in the cytoplasm. Nucleocapsids were observed to bud through membranes of the endoplasmic reticulum and/or Golgi apparatus into dilated vesicles. Egress of mature virions occurs primarily by exocytosis and, only very rarely, by budding directly at the plasma membrane. Morphologically similar viruses had previously been isolated from grass carp (Ctenopharyngodon idella), blue crab (Callinectis sapidus), European shore crab (Carcinus maenas) and shrimp (Penaeus monodon). To date, none of them has been classified. In summary, the first characterization of a new virus that might represent a member of a novel virus family that has morphological features resembling those found in rhabdo-, corona- and baculoviruses is presented.  (+info)

Accumulation of ammonia in the body and NH(3) volatilization from alkaline regions of the body surface during ammonia loading and exposure to air in the weather loach Misgurnus anguillicaudatus. (7/72)

The weather loach Misgurnus anguillicaudatus inhabits rice fields that experience drought in summer and ammonia loading during agricultural fertilisation. Exposure of specimens to ammonia led to the accumulation of ammonia in muscle, liver and blood. The level of ammonia reached in the plasma was the highest reported among fishes. Ammonia was not detoxified to urea, and urea excretion rate was unaffected by ammonia exposure. Fish acidified the water to reduce ammonia loading. Ammonia loading, unlike aerial exposure, did not induce glutamine synthesis, and there was no accumulation of glutamine. This is a unique observation different from those reported for other fishes in the literature. An initial switch to partial amino acid catabolism led to the accumulation of alanine and was probably associated with a decreased rate of ammonia production. Aerial exposure led to decreases in rates of ammonia and urea excretion, as well as the accumulation of tissue ammonia. As the internal ammonia levels increased, M. anguillicaudatus was able to excrete some ammonia in the gaseous form (NH(3)). The percentage of ammonia excreted as NH(3) increased with time of exposure and with increasing temperature. It appears that air-breathing through the gut is involved, with the anterior portion of the digestive tract playing a central role: it became significantly more alkaline in fish exposed to air or to environmental ammonia. The skin, which also became more alkaline during air exposure, may also be involved in ammonia volatilization in air-exposed fish. This represents the first report of a fish using volatilization of NH(3) as part of a defence against ammonia toxicity. It can be concluded that the main strategy adopted by M. anguillicaudatus confronted with ammonia loading or air exposure is to tolerate high ammonia levels in the tissues. During periods of elevated tissue ammonia levels, some ammonia is lost by volatilization via air-breathing using the gut. In addition, some ammonia may be lost across the skin during air exposure.  (+info)

Motility of minute intestinal fluke, Haplorchinae spp, metacercariae in fish dishes prepared by different uncooked methods. (8/72)

CONTEXT: Fish-borne trematode is a worldwide problem, with the number of people infected by liver flukes alone estimated at 21 million. In addition to the major liver flukes, Opisthorchis viverrini and Clonorchis sinensis, several types of intestinal flukes also use cyprinoid fish as the intermediate host. Traditional ingestion of undercooked and uncooked fish preparations is a major factor in pathogen acquisition. OBJECTIVE: To examine the motility of Haplorchinae spp metacercariae in matched minnows using a number of preparation methods that mimic traditional practices. DESIGN: Several freshly killed freshwater fish, Cyclocheilichthys armatus, were purchased from the local market and sent to the authors' laboratory to be examined under a stereoscopic microscope for active Haplorchinae spp metacercariae. A total of 10 fish were infected with many active metacercariae and used in the preparation of uncooked fish dishes. Five different raw fish dishes that mimic traditional meals (2 fishes/dish) were prepared using the following methods: 1) left to dry at room temperature; 2) frozen at -20 Celsius; 3) refrigerated at 4 Celsius; 4) marinated in saline (5% sodium chloride solution); and 5) marinated in 5% acetic acid solution to mimic traditional vinegar. The motility of the metacercariae in each of these dishes was examined under a stereoscopic microscope. Motility was estimated as the level of activity or degeneration of the metacercariae at the start of the experiment and then every 30 minutes until all the parasites appeared degenerate (and therefore, presumably not viable). RESULTS: Degeneration of the parasites was slowed by cooling: degeneration of all metacercariae took approximately 5 hours in the refrigerated or frozen fish, compared with 3 hours in all other dishes left at room temperature. CONCLUSION: The study substantiates the epidemiologic data demonstrating transmission of these types of pathogens despite freezing, pickling, and salting. Although the tradition of eating uncooked fish is deeply rooted in Thailand, constant efforts need to be made to discourage this practice.  (+info)

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