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At least 19 recordsLinked to original sources
PubMed2005

Takifugu obscurus is a euryhaline fugu species very close to Takifugu rubripes 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. RESULTS: The following six Takifugu species were used for the analyses: T. obscurus, T. rubripes, T. niphobles, T. pardalis, T. poecilonotus, and T. porphyreus. When transferred to FW, only T. obscurus could survive while the others could not survive more than ten days in FW. During this course of FW adaptation, serum Na+ concentration of T. obscurus decreased only slightly, but a rapid and large decrease occurred even in the case of T. niphobles, a peripheral fresh water species that is often seen in brackish river mouths. Phylogenetic analysis using nucleotide sequences of the mitochondrial 16S ribosomal RNA gene of each species indicated that the six Takifugu species are very closely related with each other. CONCLUSION: T. obscurus is capable of adapting to both FW and SW. Its genomic sequence shares a very high homology with those of the other Takifugu species such that the existing Takifugu genomic information resources can be utilized. These properties make "mefugu", which has drawn little attention from animal physiologists until this study, a useful model animal for studying the molecular mechanism of maintaining body fluid homeostasis.

Adaptation, Physiological↗
PubMed2002

The annual toxicological profiles of two common puffer fish, Takifugu niphobles (Jordan and Snyder) and Takifugu alboplumbeus (Richardson), collected along Hong Kong coastal waters.

The toxicological profiles of two local common puffer fish, Takifugu niphobles (Jordan and Snyder) and Takifugu alboplumbeus (Richardson), collected in Hong Kong waters were investigated continuously for 14 months (June 1997-August 1998). Their annual spawning seasons (as evident by the enlargement of gonads and presence of eggs in the ovary) were found to be from October to February (four consecutive months) and December to February (two consecutive months), respectively. The toxicities of their internal organs were determined by standard mouse bioassay and expressed in terms of mouse units (MU). The ovary (in both species) and liver (only in T. niphobles) were discovered to be moderately toxic (100-1000 MU/g) in their non-spawning seasons. Whilst all the intestine and skin were weakly toxic (between 10 and 100 MU/g), their flesh, however, was basically non-toxic (less than 10 MU/g) throughout the whole year. The testes, which were only developed in their spawning seasons, were also non-toxic. This study showed that the toxicological profiles of both of the two species had prominent seasonal patterns which were highly related to their spawning seasons. Contrary to the most common belief, both species were discovered to be relatively less toxic during their spawning seasons.

Animals↗
PubMed2005

Evolution of vertebrate E protein transcription factors: comparative analysis of the E protein gene family in Takifugu rubripes and humans.

E proteins are essential for B lymphocyte development and function, including immunoglobulin (Ig) gene rearrangement and expression. Previous studies of B cells in the channel catfish (Ictalurus punctatus) identified E protein homologs that are capable of binding the muE5 motif and driving a strong transcriptional response. There are three E protein genes in mammals, HEB (TCF12), E2A (TCF3), and E2-2 (TCF4). The major expressed E proteins found in catfish B cells are homologs of HEB and of E2A. Here we sought to define the complete family of E protein genes in a teleost fish, Takifugu rubripes, taking advantage of the completed genome sequence. The catfish CFEB (HEB homolog) sequence identified homologous E-protein-encoding sequences in five scaffolds in the Takifugu genome database. Detailed comparative analysis with the human genome revealed the presence of five E protein homologs in Takifugu. Single genes orthologous to HEB and to E2-2 were identified. In contrast, two members of the E2A gene family were identified in Takifugu; one of these shows the alternative processing of transcripts that identifies it as the ortholog of the E12/E47-encoding mammalian E2A gene, whereas the second Takifugu E2A gene has no predicted alternative splice products. A novel fifth E protein gene (EX) was identified in Takifugu. Phylogenetic analysis revealed four E protein branches among vertebrates: EX, E2A, HEB, and E2-2.

Animals↗
PubMed2001

Molecular phylogeny and species identification of pufferfish of the genus Takifugu (Tetraodontiformes, Tetraodontidae).

The phylogenetic relationships and species identification of pufferfishes of the genus Takifugu were examined by use of randomly amplified polymorphic DNA (RAPD) and sequencing of the amplified partial mitochondrial 16S ribosomal RNA genes. Amplifications with 200 ten-base primers under predetermined optimal reaction conditions yielded 1962 reproducible amplified fragments ranging from 200 to 3000 bp. Genetic distances between 5 species of Takifugu and Lagocephalus spadiceus as the outgroup were calculated from the presence or absence of the amplified fragments. Approximately 572 bp of the 16S ribosomal RNA gene was amplified, using universal primers, and used to determine the genetic distance values. Topological phylogenic trees for the 5 species of Takifugu and outgroup were generated from neighbor-joining analysis based on the data set of RAPD analysis and sequences of mitochondrial 16S rDNA. The genetic distance between Takifugu rubripes and Takifugu pseudommus was almost the same as that between individuals within each species, but much smaller than that between T. rubripes, T. pseudommus, and the other species. The molecular data gathered from both analysis of mitochondria and nuclear DNA strongly indicated that T. rubripes and T. pseudommus should be regarded as the same species. A fragment of approximately 900 bp was amplified from the genome of all 26 T. pseudommus individuals examined and 4 individuals of intermediate varieties between T. rubripes and T. pseudommus. Of the 32 T. rubripes individuals, only 3 had the amplified fragment. These results suggest that this fragment may be useful in distinguishing between T. rubripes and T. pseudommus.

Journal Article↗
PubMed2006

Accumulation of tetrodotoxin (TTX) in Pseudocaligus fugu, a parasitic copepod from panther puffer Takifugu pardalis, but without vertical transmission--using an immunoenzymatic technique.

The caligid copepod Pseudocaligus fugu, a common parasite on the body surface of both toxic (Takifugu pardalis) and cultured, non-toxic (Takifugu rubripes) puffer fishes, was isolated and analyzed for the presence of tetrodotoxin (TTX) using a monoclonal anti-TTX antibody-based immunohistochemical technique. Histological sections of female P. fugu from Takifugu pardalis explicitly revealed that positive brown staining was visible in regions of gut and appendages, and also in the general body tissues from the prosome to the urosome. It is absent from the epicuticle, ovary, oviduct, uterus and egg sacs, where clear negative blue color reaction was obtained. In contrast, the caligids on cultured, non-toxic Takifugu rubripes, considered as negative control, had no sign of TTX. The results indicate that there is no vertical transmission of TTX in the parasitic caligids, which could acquire TTX by feeding on the toxic mucus and skin tissues of host puffer fish.

Animals↗
PubMed2004

Monoclonal antibodies recognising serum immunoglobulins and surface immunoglobulin-positive cells of puffer fish, torafugu (Takifugu rubripes).

Immunoglobulin of the torafugu, Takifugu rubripes, was purified by a combination of precipitation by low ionic strength dialysis and gel filtration. The Ig was used to immunise mice for the production of monoclonal antibody (MAb). Supernatants of hybridoma cultures were screened by enzyme-linked immunosorbent assay using purified-torafugu Ig-coated plates, and two stable hybridomas producing MAbs against torafugu Ig were obtained. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis under reducing conditions and Western blotting indicated that one MAb (16F3) was specific for the deglycosylated heavy chain of torafugu, and the other MAb (4H5) did not bind to the reduced Ig, suggesting that 4H5 recognised the higher-order structure of Ig. Under non-reduced conditions, both MAbs recognised mainly a 750 kDa band and also minor bands of 672, 410 and 205 kDa. MAb 16F3- and 4H5-primed magnetic beads (Dynabeads) adsorbed 84.9+/-3.3% and 63.6+/-4.4% of the torafugu Ig, respectively. The Ig adsorbed by MAb 16F3-primed Dynabeads was reactive to 4H5 on immunoblotting, and vice versa, indicating that the epitopes for both MAbs are held on the same Ig molecule. Both of these MAbs cross-reacted extensively with the Ig of other Takifugu species, but not with other genus. The MAbs were used to identify surface Ig-positive lymphocytes in the spleen, pronephros, peripheral blood and thymocytes of torafugu by flow cytometry. Flow cytometric analysis of the cells in the lymphocyte-enriched fraction revealed that 50.2+/-6.9% in the PBL, 11.8+/-1.7% in the mesonephros, 13.3+/-2.1% in the pronephros, 42.5+/-4.3% in the spleen and 3.2+/-0.6% in thymus were reactive to 4H5 or 16F3.

Animals↗
PubMed2003

Identification and comparative analysis of the RpL14 gene from Takifugu rubripes.

The ribosomal protein RpL14 gene has been characterized in several species, including, human, rat and fruit fly. Haploinsufficiency for the gene causes the Minute phenotype in Drosophila, and it has been proposed as a regulator in the tumorigenic pathway in human. Several features concerning the gene structure have been studied, and some of these differ between human/rat and Drosophila. To address functional and evolutionary questions about these differences we have isolated and sequenced a cDNA and a genomic clone covering the RpL14 gene from the pufferfish Takifugu rubripes (Fugu). The Fugu RpL14 gene is approximately 2 Kb, with 5 introns, and encodes a protein of 137 amino acids. The protein contains a KOW-motif and a nuclear localization signal, which are conserved among a wide range of RPL14 proteins. On the other hand, a variable amino acid (alanine) repeat observed in human is missing in Takifugu rubripes, and the protein is shorter than its mammalian counterparts. Compared with human, the RpL14 gene in Fugu contains introns localized at identical positions in the gene, and most of them are shorter. A comparison of the RpL14 gene structure from a broad range of organisms indicates that both loss and gain of introns have occurred during the evolution of the gene.

Amino Acid Sequence↗
PubMed2005

A genetic linkage map for the tiger pufferfish, Takifugu rubripes.

The compact genome of the tiger pufferfish, Takifugu rubripes (fugu), has been sequenced to the "draft" level and annotated to identify all the genes. However, the assembly of the draft genome sequence is highly fragmented due to the lack of a genetic or a physical map. To determine the long-range linkage relationship of the sequences, we have constructed the first genetic linkage map for fugu. The maps for the male and female spanning 697.1 and 1213.5 cM, respectively, were arranged into 22 linkage groups by markers heterozygous in both parents. The resulting map consists of 200 microsatellite loci physically linked to genome sequences spanning approximately 39 Mb in total. Comparisons of the genome maps of fugu, other teleosts, and mammals suggest that syntenic relationship is more conserved in the teleost lineage than in the mammalian lineage. Map comparisons also show a pufferfish lineage-specific rearrangement of the genome resulting in colocalization of two Hox gene clusters in one linkage group. This map provides a foundation for development of a complete physical map, a basis for comparison of long-range linkage of genes with other vertebrates, and a resource for mapping loci responsible for phenotypic differences among Takifugu species.

Animals↗
PubMed2006

[Characterization and phylogenetic analysis of the cytochrome oxidase subunit I gene of mitochondrial genome from Takifugu fasciatus].

The Takifugu fasciatus mitochondrial cytochrome oxidase I gene (COI) and its associated tRNA genes were sequenced by PCR. The open reading frame of COI gene contains 1,546 bp nucleotides, encoding a putative protein of 515 amino acid residues. The pattern of codon usage of the COI gene is less biased toward A+T. The COI gene of T. fasciatus shows a high degree of homology with that from the other 14 fish species recorded in the GenBank and has 97.6% homology with Takifugu rubripes, 76.5% with Masturus lanceolatus and 75.4% with Mola mola. The phylogenetic trees show that the relationships based on the homology is consistent with the morphological and taxonomic results. Predicted secondary structures of the tRNA genes suggest that they have the classical cloverleaf structures.

Amino Acid Sequence↗
PubMed2005

Characterization and expression analysis of CD3varepsilon and CD3gamma/delta in fugu, Takifugu rubripes.

CD3 is an essential component of the CD3-TCR complex. In this report, we describe the cloning, characterization, and expression analysis of the CD3varepsilon and CD3gamma/delta chain genes from fugu, Takifugu rubripes. Two distinct CD3varepsilon homologue cDNAs, designated as CD3varepsilon-1 and CD3varepsilon-2, and a CD3gamma/delta homologue cDNA were isolated from the fugu thymus. The deduced amino acid sequences of these cDNAs exhibit conserved essential CD3 chain motifs and overall structures. RT-PCR analysis demonstrated that the CD3varepsilon and CD3gamma/delta genes were expressed in lymphoid organs (e.g. thymus, head kidney, trunk kidney and spleen), mucosal tissues (gill, skin, and intestine), and peripheral blood leucocytes (PBL). The CD3 and TCRalpha genes were expressed only in the surface IgM- population, which were separated from PBL using an anti-fugu IgM monoclonal antibody. In addition, in situ hybridization confirmed that CD3-expressing cells were distributed randomly in the head kidney, trunk kidney, and spleen, but in the thymus were restricted to the lymphoid outer zone and epithelioid inner zone only. Collectively, these results suggest that CD3 molecules are useful markers for the identification of T cells in teleost fish. The present study thus provides a critical step in identifying T cells in this model organism.

Animals↗
PubMed2006

Carbohydrate-binding site of a novel mannose-specific lectin from fugu (Takifugu rubripes) skin mucus.

Pufflectin-s, identified in the skin mucus of the fugu Takifugu rubripes, is a novel mannose-specific lectin with similar structure to monocotyledonous plant lectins. In the present study, mutational analysis was used to reveal the mannose-binding sites of pufflectin-s. Putative binding sites were mutated as follows: binding site 1; rPL-D32E (Asp32-->Glu32), rPL-N34S (Asn34-->Ser34) and rPL-V36A (Val36-->Ala36) whereas binding site 2; rPL-D61E (Asp61-->Glu61), rPL-N63S (Asn63-->Ser63) and rPL-V65A (Val65-->Ala65). All recombinant proteins were expressed in Escherichia coli, purified with two chromatographic steps, and then subjected to mannose-binding assay by affinity chromatography. Recombinant wild-type pufflectin-s (rPL-wt) as well as three mutants with changes in binding site 2 could bind to mannose, in contrast to the three mutants with changes in binding site 1 in which mannose-binding activity was completely lost. These results clearly demonstrate that, at the least, binding site 1 is critical to mannose-binding activity in pufflectin-s.

Amino Acid Sequence↗
PubMed2004

Purification and properties of proteinaceous trypsin inhibitors in the skin mucus of pufferfish Takifugu pardalis.

A screening assay for inhibitory activity against trypsin in skin mucus from 29 species of fishes reveals a wide distribution of trypsin inhibitors in skin mucus and relatively high antitryptic activity in pufferfish of the family Tetraodontidae. Two trypsin inhibitors termed TPTI 1 and 2 were purified to homogeneity from the skin mucus of Takifugu pardalis by salting out, lectin affinity, anion exchange FPLC and gel filtration HPLC. Both inhibitors are acidic glycoproteins, with an apparent molecular mass of 57 kDa in SDS-PAGE, pI below 4 and 1.9% reducing sugar for TPTI 1 and with an apparent molecular mass of 47 kDa in SDS-PAGE, pI 5.2 and 0.8% reducing sugar for TPTI 2. The inhibitors effectively repress the catalytic activity of trypsin and alpha-chymotrypsin, and therefore can be classified as serine protease inhibitors. The inhibitory constants against trypsin were 4.9x10(-8) M for TPTI 1 and 3.9x10(-8) M for TPTI 2. Both inhibitors react with trypsin at a molar ratio of 1:1, although TPTI 1 reversibly inactivates the proteolytic activity of trypsin non-competitively and TPTI 2, competitively. The trypsin inhibitors in the skin mucus of T. pardalis may function as defense substances to neutralize serine proteases released by invasive pathogens.

Amino Acids↗
PubMed2005

Identification of pepsinogen gene in the genome of stomachless fish, Takifugu rubripes.

Pepsinogen is a precursor of pepsin, a gastric specific protease belonging to the aspartic proteinase family. In teleosts, several species, such as zebrafish and puffer, have independently lost gastric glands. So whether puffer have pepsinogen gene or not is an interesting issue. A search of GSS database for pufferfish, Takifugu rubripes, revealed five different aspartic proteinase genes in its genome. One of them (pPep) has typical pepsinogen structure and belongs to the fish pepsinogen cluster by phylogenic analysis. The pPep antisense probe hybridized to the gastric glands of flounder stomach. Therefore, we concluded that pPep is a pufferfish pepsinogen. The pufferfish pepsinogen mRNA was not expressed in the digestive organs but specifically in the skin. We speculated that while Tetraodontiformes evolutionarily lost gastric glands, pufferfish pepsinogen acquired an alternative function to food digestion.

Amino Acid Sequence↗
PubMed2006

B-lymphocyte-induced maturation protein-1 (Blimp-1) gene of torafugu (Takifugu rubripes).

Homologous gene of B-lymphocyte-induced maturation protein-1 (Blimp-1) of torafugu (Takifugu rubripes) was identified by tblast search analysis. RT-PCR and 5'RACE clearly defined the sequence of the UTR and coding region which has been ambiguously determined by tblast analysis. Fugu Blimp-1 was mainly expressed in the lymphoid organs. These finding imply that Blimp-1 would take a major role in the terminal differentiation of B-cells to plasma cells in fish.

Amino Acid Sequence↗
PubMed2004

Body temperature and evolutionary genomics of vertebrates: a lesson from the genomes of Takifugu rubripes and Tetraodon nigroviridis.

In this paper, we provide evidence for the body temperature effect on the formation of GC-rich isochores, by analysing genomic sequences from two puffer fishes living at different temperatures. The higher body temperature of Tetraodon nigroviridis compared to Takifugu rubripes (DeltaT approximately 15 degrees C) appears to be the cause of a higher compositional heterogeneity of the former due to the formation of GC-rich regions. Such an effect does not only concern large DNA segments but also coding sequences.

Adaptation, Physiological↗
PubMed2005

Identification of three isoforms for mitochondrial adenine nucleotide translocator in the pufferfish Takifugu rubripes.

Three adenine nucleotide translocator (ANT) genes were identified through in silico data mining of the Fugu genome database along with isolation of their corresponding cDNAs in vivo from the pufferfish (Takifugu rubripes). As a result of phylogenetic analysis, the ANT gene on scaffold_254 corresponded to mammalian ANT1, whereas both of those on scaffold_6 and scaffold_598 to mammalian ANT3. The ANT gene encoded by scaffold_6 was expressed ubiquitously in various tissues, whereas the ANT genes encoded by scaffold_254 and scaffold_598 were predominantly expressed in skeletal muscle and heart, respectively.

Amino Acid Sequence↗
PubMed2005

Analysis and characterization of the expression of the secretory and membrane forms of IgM heavy chains in the pufferfish, Takifugu rubripes.

We investigated the structure and expression of immunoglobulin genes in the pufferfish, Takifugu rubripes, a highly prized and economically important fish species. The cDNA fragment that partially encodes the constant region of the IgM heavy chain was isolated in these animals by RACE using degenerate primers after which it was used as a probe for screening IgM heavy chains in a fugu splenic cDNA library. The structural feature of the constant region of fugu sIgM was found to consist of four constant domains (CH1 to CH4), while mIgM was shown to contain a deletion of the CH4 domain, and its transmembrane domain was directly spliced to the CH3 domain as found in other teleosts. This feature may be common to all teleosts. In addition, five VH genes isolated in this study fell into two families based on their variability. Analysis of genomic sequences from the fugu genomic database also showed that there are only two VH families in the genome. The IgM gene was preferentially expressed in presumptive lymphoid tissues. Moreover, in situ hybridization revealed that large numbers of IgM positive cells were widely distributed throughout the spleen, head kidney, kidney, and thymus, confirming that these tissues were major sites of antibody production in fish. The expressions of IgM in the mucosal organs such as the skin, gills, and intestine suggest that they, too, contribute to humoral immunity in aquatic animals. The expression of IgM mRNA in the early development stages of this fish suggests that its larval form possesses a protective defense mechanism against foreign invaders.

Animals↗
PubMed2005

Molecular cloning of the BCL-6 gene, a transcriptional repressor for B-cell differentiation, in torafugu (Takifugu rubripes).

B-cell lymphoma-6 (BCL-6) is a transcriptional repressor that prevents the terminal differentiation of mature B-cells to plasma cells, and is essential for germinal center formation in the primary lymphoid organs of mammals. In this study, we identified the BCL-6 gene in torafugu (Takifugu rubripes) using the torafugu genome database, and analyzed the expression of BCL-6 mRNA in various tissues of torafugu, using RT-PCR. The BCL-6 gene consisted of eight exons and seven introns spanning a genome of ca. 3.3 kb. BCL-6 mRNA contained a 2112 bp open reading frame encoding 703 amino acids, with a predicted protein size of 78.8 kDa. The predicted torafugu BCL-6 primary structure contains two conserved specific motifs, the BTB/POZ domain at the N-terminus and the sixC2H2-type zinc finger motifs at the C-terminal region. The homology of torafugu BCL-6 to those of zebrafish (Danio rerio), Xenopus laevis, mouse (Mus musculus) and human (Homo sapiens) is 76, 59, 60 and 60%, respectively. RT-PCR analysis revealed that BCL-6 mRNA is highly expressed in pronephros, thymus, intestine, ovary, brain, nasal cavity and muscle. These results imply that torafugu BCL-6 is involved in regulation of B-cell differentiation in torafugu.

Amino Acid Motifs↗