Carassius Cuvieri Research Articles

Diversity and seasonal changes in lactic acid bacteria in the intestinal tract of cultured freshwater fish

The composition of intestinal lactic acid bacteria (LAB) in fish species in Lake Kasumigaura was analyzed. First, the LAB composition of four fish species, silver carp (Hypophthalmichthys molitrix), common carp (Cyprinus carpio), channel catfish (Ictalurus punctatus) and deepbodied crucian carp (Carassius cuvieri), were analyzed in July and December 2001. In all these species, the predominant LAB was Lactococcus lactis in July and Lactococcus raffinolactis in December, strongly suggesting that the predominant intestinal LAB of fish in Lake Kasumigaura is L. lactis in summer and L. raffinolactis in winter, irrespective of fish species. Next, a yearlong analysis of changes in LAB composition was performed in common carp from April 2002 to March 2003. The predominant LAB was L. lactis in summer when water temperatures were above 20 °C, and L. raffinolactis in winter, when temperatures ranged between 4 and 10 °C. The change in the predominate LAB occurred in spring and autumn when water temperatures were between 13 and 17 °C. During these intermediate periods, LAB composition was variable. The change in predominant LAB was revealed to be due to the difference in the growth profile of the two species: L. lactis grew faster at above 20 °C, but at lower temperatures, L. raffinolactis grew successfully. RAPD analysis of isolated strains revealed that L. lactis strains in common carp intestine were limited to a few strains throughout the seasons but L. raffinolactis strains were diverse.

Plasma vitellogenin levels in male common carp Cyprinus carpio and crucian carp Carassius cuvieri of Lake Kasumigaura

: In order to investigate the possible influence of estrogenic environmental endocrine disruptors on the reproductive activity of fish in Lake Kasumigaura, plasma levels of vitellogenin (VTG), a biomarker of estrogen exposure, were measured in wild and cultured male common carp Cyprinus carpio and wild crucian carp Carassius cuvieri. Testicular histology and plasma steroid hormone levels were also examined. Fish were collected from June 1998 to August 1999. Plasma VTG levels in most fish examined were below a detection limit (40 ng/mL) throughout the sampling period, and a small amount of VTG (43.5 ng/mL–1680 ng/mL) compared to that in females was detected in some fish. Active spermatogenesis in the testis and increased levels of plasma sex steroids were observed in most of the fish examined. Thus, no marked influence of estrogenic chemicals was detected in the reproductive activity of male common carp and crucian carp in Lake Kasumigaura collected from the sampling sites in the present investigation.

The Current Status of the Distribution of Introduced Fish in Large River Systems of South Korea

A nation-wide survey of introduced fish fauna in large river systems (>4th order streams, 28 sites, 9 river systems, total area 75,000 km 2 ) was conducted from July 1999 to January 2000 in South Korea. A total of 62 fish species (12,317 individuals, 16 families) were collected from two sampling programs. These included 32% of 194 known freshwater ichthyofauna of S. Korea. Dominant and subdominant species were Zacco platypus (16.2% relative abundance), Acheilognathus intermedia (10.6%), A. rhombea (7.2%), Opsariichthys bidens (7.1%), and Carassius auratus (6.9%). Fifteen exotic fish species have been introduced in S. Korea for food sources and about 120 species for aquarium use since the 1950s. In this study, five of the introduced food species were collected (Carassius cuvieri, 24 sites; Micropterus salmoides, 13 sites; Lepomis macrochirus, 7 sites; Oreochromis niloticus and Cyprinus carpio, 3 sites). C. cuvieri and M. salmoides were common (subdominant at 5 sites) and followed by L. macrochirus. These species were spread widely (93%; 26 sites) over all the study sites. Future research must consider the impacts of these exotic fish on natural ecosystem structure and function.

Identification of two metallothionein isoforms by molecular cloning of their cDNAs in fresh-water fish, crucian carp (Carassius-cuvieri)

Generally, there are two major isoforms of metallothionein (MT) in mammals. In this study two cDNAs of metallothionein, MT-A and MT-B, in a fresh-water fish, crucian carp (Carassius cuvieri), were cloned by the rapid amplification of cDNA ends (RACE). The homology of their reading frame is about 92.3%. The sequence analysis of both cDNAs gave the structures of coding regions corresponding to 60 amino acid residues, and the structures of complete 3′-untranslated regions in which a significant difference in the size of their 3′-untranslated regions (130 bp for MT-A and 280 bp for MT-B) exists. The results of amino acid sequencing of both MT-1 and MT-2 purified by HPLC are identical to those deduced from MT cDNA genes, indicating that MT-1 is from MT-A gene and MT-2 is from MT-B gene respectively. No blocking in the N-terminal of MT-2 isoform was the first case found in vertebrates, most of which were blocked by acetylation. These results suggest that there were differential controls at the transcription level and after translation of these two MT isoforms. And this gives a clue to understand the diversities of their functions.

Biological characteristics of starved Aeromonas hydrophila which contribute to virulence in crucian carp, Carassius cuvieri

In a previous study it was found that the starved Aeromonas hydrophila is more pathogenic to carp and goldfish than the cultured bacterium. To know the reason for higher virulence of starved A. hydrophila, pathogenic properties of starved and cultured bacteria were studied using crucian carp. Higher virulence of starved bacterium than cultured one was confirmed by using crucian carp. The number of bacteria that adhered to skin of crucian carp was significantly higher in the starved A. hydrophila than the cultured bacterium. Moreover, the starved A. hydrophila was more resistant to the killing activity of body surface mucus, serum and phagocytosis by head kidney macrophages compared to the cultured bacterium. From this study it was found that the starved A. hydrophila possesses different biological properties against crucian carp defense, which may be related to higher virulence to host than the cultured one.

Induction of two major isoforms of metallothionein in crucian carp ( Carassius cuvieri) by air-pumping stress, dexamethasone, and metals

The induction of metallothionein (MT) by physical and chemical stress was assessed using the fresh-water fish, crucian carp ( Carassius cuvieri Temminck et Schlegel). The fish exposed to violent air-pumping stress for 6 days revealed time-dependent induction of MT-like metal-binding proteins in both their livers and kidneys. Their hepatic contents after exposure to stress were elevated to twice the basal level with 24 h, resulting in more than a 3-fold increase at 144 h, whereas their renal contents gradually increased after 24 h and reached the same level as that in the liver around 96 h. Two major inducible proteins were purified from livers of fish exposed to stress and were shown to be MT based upon their chromatographic behavior, UV absorption spectra and their molecular weights. Consequently, they were termed ccMT-1 and ccMT-2, according to their elution sequence upon anion-exchange chromatography. Both proteins mainly bound zinc in their endogenous forms and showed different immunogenicity to rat and rabbit MTs. Dexamethasone, a potent inducer for MT synthesis in mammals, induced the production of both isoforms in crucian carp, whereas cadmium and zinc ions prominently induced the synthesis of ccMT-2. These results indicate that crucian carp have the ability to produce MTs in response to various kinds of environmental stress and that violent air-pumping stress in crucian carp may induce MT synthesis, in part, via the release of endogenous factor(s), such as glucocorticoids.

河口湖における魚類相の変遷とそれをとりまく環境

This lake was mainly stocked with Carassius cuvieri and Hypomesus by the Kawaguchiko Fishermen's Association until the 1980s. However, since Micropterus salmoides salmoides were confirmed to exist in the lake in 1973, by early 1985 Hypomesus were no longer caught. This condition continued for a short period ; then, in the 1990s, the fish species composition showed a great change in the lake. Micropterus salmoides salmoides and Salmo (Oncorhynchus) mykiss became the main catch. As a result, 370, 000 anglers visited Lake Kawaguchi in 1996, against 35, 000 in 1978. The total number of anglers who visit the lake is increasing rapidly. At present, Lake Kawaguchi has become the most famous lake for fly fishing in Japan. In order to respond to the demand of so many anglers, the Kawaguchiko Fishermen's Association stocks the lake with many species of carnivorous fish. Moreover, they annually stock an abundance of small plankton-feeding fish which in turn become the food of carnivorous fish. Owing to the above circumstances, Lake Kawaguchi has become like an artificial fishing pond, with disturbing effects on the lake ecosystem. The ecological impact on other aquatic organisms has become a cause for concern.

ＲＡＰＤ‐ＰＣＲおよびアイソザイムパターンによるギンブナー腹子のクローン性の証明

The eggs of Ginbuna Carassius langsdorfii (all female triploids) were inseminated by the sperm of a Gengoroubuna Carassius cuvieri and a commom carp Cyprinus carpio respectively. DNA extracted from blood of parents and offsprings were amplified using 20 random primers and separated by electrophoresis (RAPD-PCR). Isozymes of muscle and liver of parents and offsprings were assayed by the horizontal starch gel electrophoresis. Distinct differences by maternal fish were observed in the patterns of both RAPD-PCR (17 primers) and isozymes (CK, EST, GPI, PGM), but those of offsprings produced by crossing with Gengoroubuna and common carp respectively were the same completely within the maternal fish. Therefore, the results obtained in this study verified that the offsprings from Ginbuna were clonal genetically, being the same with maternal fish throughout the genome.

Disease resistance gene transfer in grass carp by sperm chromosome fragmentation and gynogenesis

Diploid gynogenesis was induced in Japanese crucian carp (Carassius cuvieri) eggs using UV-irradiated genetically inactive spermatozoa from mirror carp (Cyprinus carpio L.) or blunt snout bream (Megalobrama amblycephala), with or without cold shock. The optimal radiation dosage was 4200 mJ/cm2 and 3600 mJ/cm2 for mirror carp and blunt snout bream sperm, respectively. At this dosage and without cold shock, the yields were (32.4±3.3)% vs. (33.8±1.4)% gynogenetic haploids and (0.7±0.3)% vs. (0.5±0.3)% hybrid diploids, respectively. At the optimal UV dosage but with cold shock (2 min after fertilization, 0–4°C for 40 min), the hatching rates were (27.8±2.1)% and (29.4±3.3)%, respectively. From hatching to feeding, (15.7±3.4)% and (23.6±4.1)% normal gynogenetic diploids were recorded, respectively. Survival of normal gynogenetic diploids was 56% out of the hatched fry when using irradiated spermatozoa of mirror carp, which was lower than that (up to 80%) when using irradiated spermatozoa of blunt snout bream. This indicated that the sperm of blunt snout bream, with distant genetic relation to the maternal Japanese crucian carp, was more effective than that of mirror carp to induce diploid gynogenesis. The nature of the gynogenetic progeny was identified with external appearance, chromosome number and gonad structure. The presence of only females in gynogenetic progeny probably suggested XX genotype in the female Japanese crucian carp. The gynogenetic diploids have potential values such as faster growth and stronger disease resistance than the normal Japanese crucian carp. All gynogenetic progeny possessed 100 chromosomes whereas all J x B crosses were triploid with 124 chromosomes. The formation of the new triploid hybrids in J x B crosses may be useful in aquaculture.

Clinostomum complanatum (Trematoda) infection in freshwater fish from fish dealers in Tottori, Japan.

During the period January 1989 through February 1991, 327 freshwater fish of 3 different species (Carassius cuvieri, Cobitis anguillicaudatus and Hypomesus transpacificus) purchased from 7 fish dealers in Tottori City were investigated for the metacercarial infection of Clinostomum complanatum. Among them, 20.5% (16/78) of C. cuvieri were infected with this fluke. Each infected fish harbored 1 to 30 metacercariae. The sites and rates of parasitization of metacercariae in the infected fish were 42.4% in the body muscles, 30.3% in the muscles at the pectoral fin, 21.2% in the tissues around the gills and 6.1% in the cheek muscles.

Clinostomum complanatum (Trematoda: Clinostomatidae) in five new fish hosts in Japan.

Metacercariae of Clinostomum complanatum were found in six species of natural freshwater fishes collected at Koyama Pond in Tottori City of Tottori Prefecture, Japan. Five of these fish species are reported here as new records for second intermediate hosts of C. complanatum in Japan: the silver crucian carp (Carassius gibelio langsdorfi), the deepbodied crucian carp (Carassius cuvieri), the carp (Cyprinus carpio), the topmouth gudgeon (Pseudorasbora parva) and the rose bitterling (Rhodeus ocelatus).

The potent activity of fresh water fish kidney cells in cell-killing I. Characterization and species-distribution of cytotoxicity

Kidney cells of fresh water fishes, Cyprinus carpio (carp), Carassius cuvieri (crucian carp), Ctenopharyngodon idella (grass carp), Misgrunus anguillicandatus (orienta) weather fish) and Channa argus (northern snakehead) were markedly cytotoxic against certain established mammalian cell lines when incubated at 25°C in the absence of specific antibody. Cytotoxicity occurred immediately after incubation with targets, increased exponentially and was accomplished within 6 hrs. The cytotoxicity was mediated by the intact cells but not by either their extracts or culture supernatants. The cytotoxic activity was directed against established cell lines but not normal resting cells. Under similar conditions, kidney cells of salt water fishes showed no cytotoxicity against any targets tested. Leukocytes obtained from various lymphoid organs of other normal higher vertebrates also showed no such potent cytotoxicity. These results indicate that a population(s) of kidney cells in fresh water fishes of stenohaline type carrys the killing activity with a spectrum of target cells similar to that of activated macrophages or natural killer cells in mammals.