Eel Liver Research Articles

ウナギ加工品における総水銀およびメチル水銀の残留調査

Fifty-two samples of broiled eels and broiled eel liver were analyzed for total mercury (total Hg) and methyl mercury. The mean concentrations of total Hg in broiled eels and broiled eel liver were 0.21 ppm and 0.10 ppm, respectively. Meanwhile, the mean concentrations of methyl mercury in broiled eels and broiled eel liver were 0.085 ppm and 0.039 ppm, respectively. The rate of methyl mercury to total Hg mainly ranged from 60 to 80% in broiled eels and from 35 to 65% in broiled eel liver. The total Hg concentrations of 2 samples of broiled eels and one sample of broiled eel liver exceeded the provisional regulation limit (0.4 ppm) of total Hg in fish in Japan. In these samples, the rates of methyl mercury to total Hg were lower than 20%. The muscles and the skin of broiled eels were measured separately. The ratios of skin to muscle concentration of total Hg and methyl mercury were mainly in the range from 1/10 to 1/4. The mean intakes of total Hg from broiled eels and broiled eel liver per individual were 24.6 microg and 3.1 microg, respectively. The mean intakes of methyl mercury from broiled eels and broiled eel liver per individual were 10.4 microg and 1.2 microg, respectively.

Anguilla anguilla L. liver EROD induction and genotoxic responses after retene exposure

Anguilla anguilla L. (European eel) were exposed for 8, 16, 24, and 72 h to 0 (control), 0.1, 0.3, 0.9, and 2.7 μM retene. A. anguilla L. liver ethoxyresorufin- O-deethylase (EROD) activity significantly increased during the whole exposure period to all retene concentrations, when compared to their controls. The liver cytochrome P450 content only increased after exposure to high retene concentrations (0.9 and 2.7 μM) from 8 to 24 and 72 h, respectively. Generally, liver DNA integrity decreased with increased retene concentrations. Thus, a low retene concentration (0.1 μM) was only effective at 16 h, 0.3 and 0.9 μM had an early and prolonged effect up to 24 h, and 2.7 μM decreased liver DNA integrity during the whole exposure period. However, blood DNA integrity decrease was observed in eels after 24 h exposure to 0.1 μM retene, and at 16 h to 0.3 and 0.9 μM retene, despite an early blood DNA integrity decrease at 8 and 16 h exposure to 2.7 μM retene. An early genotoxic response to retene was also observed as erythrocyte nuclear abnormalities plus Notched (ENA+ Not) frequency increase at 8, 16, and 24 h exposure to 0.1 and 0.3 μM retene as well as at 8, 16, 24, and 72 h to 0.9 μM retene. Though, the highest retene concentration (2.7 μM) only induced ENA+ Not and erythrocyte nuclear abnormalities minus Notched (ENA− Not) at 16 h exposure. The eel ENA+ Not increase was more sensitive than the ENA− Not increase as a measure of retene genotoxicity. Eel liver alanine amino transferase (ALT) increased activity reveals its enhanced transamination capacity after short-term exposure to retene. The A. anguilla L. ratio between hemoglobin concentration and red blood cells count (Hb/RBC) increased at 8 h exposure to 0.1, 0.3, and 0.9 μM retene, suggesting an initial homeostatic process.

A Note On Survival Of Infective Stage Larva Of Gnathostoma Spp. In BME Culture Medium

Dear editor, human gnathostomiasis in an important tropical parasitic infection ( 1). The major manifestation as nodular migratory eosinophilic panniculitis is suggested for this disease. More severe presentations, resulting from visceral larva migran, such as ocular and CNS gnathostomiasis are also reported. The diagnosis is confirmed by identification of the parasite from the pathological specimen. However, it is difficult to get the histological diagnosis, therefore, the immunological diagnosis for this infection is necessary. At present, Gnathostoma spinigerum third stage larvae (L3) antigen is necessary for Western blot analysis in the diagnosis of Gnathostomiasis ( 2 , 3). Acid pepsin solution is required for digestion of eel's liver (Fluta alba) to yield the larvae for antigen preparation. However, the specific antigen is excretion secretory (ES) antigen, which can be derived from viable larva. Since the larva start to degenerate within a short period, therefore, the larva derived from digestion must be used before its death. Here, we reported our result in using the BME culture medium for cultivation of the derived larva to prolong the period of usage of the harvested larva in antigen preparation.

Heavy Metal Contamination of European Eel (Anguilla anguilla) and Brown Trout (Salmo trutta) Caught in Wild Ecosystems in Spain

In this study we analyzed the pattern of copper (Cu), cadmium (Cd), lead (Pb), and mercury (Hg) accumulation in liver (as a detoxifying organ) and muscle (as the most important tissue for human consumption) of brown trout (Salmo trutta) and European eel (Anguilla anguilla) caught in two wild Spanish rivers where both species are usually angled for human consumption. Cd, Pb, and Cu accumulated preferentially in the liver of both species. Hg accumulated both in the liver and muscle in brown trout, whereas it accumulated preferentially in muscle in European eel. Both high metal content and preferential accumulation of Hg in muscle suggest that European eel is more harmful than brown trout for human consumption.

The mitochondrial tricarboxylate carrier of silver eel: chemical modification by sulfhydryl reagents.

The tricarboxylate (or citrate) carrier was purified from eel liver mitochondria and functionally reconstituted into liposomes. Incubation of the proteoliposomes with various sulfhydryl reagents led to inhibition of the reconstituted citrate transport activity. Preincubation of the proteoliposomes with reversible SH reagents, such as mercurials and methanethiosulfonates, protected the eel liver tricarboxylate carrier against inactivation by the irreversible reagent N-(1-pyrenyl)maleimide (PM). Citrate and L-malate, two substrates of the tricarboxylate carrier, protected the protein against inactivation by sulfhydryl reagents and decreased the fluorescent PM bound to the purified protein. These results suggest that the eel liver tricarboxylate carrier requires a single population of free cysteine(s) in order to manifest catalytic activity. The reactive cysteine(s) is most probably located at or near the substrate binding site of the carrier protein.

Anguilla anguilla L. genotoxic and liver biotransformation responses to abietic acid exposure

Adult eels ( Anguilla anguilla L.) were exposed for 8, 16, 24, and 72 h to 0, 0.1, 0.3, 0.9, and 2.7 μM abietic acid (AA). Genotoxicity was measured as erythrocytic nuclear abnormalities (ENA), as well as DNA strand breaks in blood and liver. Liver cytochrome P450 (P450) content, liver ethoxyresorufin O-deethylase (EROD), and glutathione S-transferase (GST) activities were determined as biotransformation biomarkers. Liver alanine transaminase (ALT) activity was also measured as an indication of tissue damage. Low AA concentrations, such as 0.1 and 0.3 μM, result in a delayed induction of A. anguilla L. liver EROD activity, whereas the higher AA concentration (2.7 μM AA) also has a delayed effect probably as a consequence of liver tissue high inhibitory concentration. The current eel liver GST activity results demonstrate that only low AA concentrations promote liver increases in GST, whereas high AA concentrations, such as 0.9 and 2.7 μM, do not alter it. The results concerning eel liver ALT activity indicate that significant liver damage is induced by high AA concentrations, such as 2.7 and 0.9 μM. The eel ENA result analysis reveals that AA is a weak ENA inducer in A. anguilla L. Blood DNA integrity results suggest that low AA concentrations promote late decreases in blood DNA integrity; nevertheless, high AA concentrations are early blood genotoxic inducers compared with low AA doses. According to the present research results with respect to eel liver DNA damage, all of the AA exposure concentrations decreased liver DNA integrity.

Large volume sample stacking capillary electrophoresis for metallothioneins analysis in eel liver

A large volume sample stacking procedure (LVSS) is developed here for metallothionein (MT) determinations in rabbit liver by using capillary electrophoresis with UV detection. A 10-time improvement in concentration-based LODs, when compared to the normal stacking mode (CE-UV analysis of samples solved in water), is achieved. The methodology is successfully applied to analysis of MTs in eel liver cytosolic extracts, preceded by an easy cleaning-up pre-treatment in order to eliminate the high salt content. Analysis of cytosol obtained from a group of eels previously exposed to Cd (induced group) resulted in several isoforms of MTs with differences in absorbance signal compared to a control group.

Sample stacking capillary electrophoresis with ICP-(Q)MS detection for Cd, Cu and Zn speciation in fish liver metallothioneins

Speciation of different metal isoforms present in metallothioneins (MTs) of living organisms requires both a high efficiency separation technique, e.g., CE, and a multielement, specific and highly sensitive detector (e.g. ICP-MS). To cope with naturally occurring low metal-MTs levels in biological systems and compensate for CE lack of sensitivity a large volume sample stacking (LVSS) methodology for CE-ICP-MS measurements is presented here. Two different CE-ICP-MS interfaces, including the use of a Babington and a HEN nebulizer, are investigated in detail and compared in terms of repeatability (%RSD) and limit of detection (LOD). By using the LVSS technique developed here the LODs obtained were improved 9–13 times. Finally, the proposed methodology was successfully applied to metal speciation studies of MT isoforms present in eel liver, both in control and Cd-induced groups, revealing a clear increase in Cd isoform signals by this metal exposure. Clear differences in profiles and signal intensities of the isoforms detected in both groups were also observed when Cu and Zn are monitored.

Genotoxic and biochemical responses in caged eel ( Anguilla anguilla L.) after short-term exposure to harbour waters

European eel ( Anguilla anguilla L.) were caged and exposed in situ for 8 and 48 h to the Aveiro offward fishing harbour water (HW) and to clean seawater under laboratory conditions (Control). Eel liver biotransformation (Phase I) was measured as ethoxyresorufin- O-deethylase (EROD) activity, cytochrome P450 ( P450) and glutathione S-transferase (GST) activity (Phase II). Genotoxic responses were determined as blood, liver and kidney DNA strand breaks as well as erythrocytic nuclear abnormalities (ENAs). HW failed to significant increase liver EROD, GST activities and ENA frequency. Nevertheless, P450 content was significantly increased after 8 and 48 h exposure. Genotoxicity measured as DNA integrity decrease was found in blood after 8 and 48 h exposure to HW, whereas in liver and kidney, it was observed after 48 h exposure to HW. Blood, kidney and liver genotoxicity may be due to the presence of polycyclic aromatic hydrocarbons (PAHs) which are genotoxic compounds and the main HW organic contaminants.

Metal speciation analysis in eel (Anguilla anguilla) metallothioneins by anionic exchange-FPLC-isotope dilution-ICP-MS

The role that different eel liver MT isoforms could play in metal sequestration was investigated here by “post-column” isotope dilution analysis (IDA) coupled to ICP-MS. Specimens of European eel (Anguilla anguilla) were exposed in aquarium tanks to 100 µg L−1 of Cd for three weeks, while a control group was kept away from metal exposure. The separation of possible MT isoforms was carried out by initial size exclusion (SEC) fractionation of eel liver cytosol, followed by anionic exchange fast protein liquid chromatography (AE-FPLC). Once final separation is accomplished, a mixed solution containing the enriched isotopes 111Cd, 65Cu, and 67Zn, was pumped at the exit of the AE column and the ratios 114Cd/111Cd, 63Cu/65Cu, and 64Zn/67Zn were monitored “on line” using an ICP-(Q)MS (in order to carry out quantitative studies). Results demonstrated that those metals were preferably bound to one major MT isoform, which would accumulate the excess of Cd in the eels exposed to this toxic metal. Moreover, sulfur analysis by ICP-(DF)MS demonstrated a clear increase of apothionein in that major hepatic MT isoform, pointing to its induction in eels under cadmium exposure. As an example of application of the described metal speciation methodology to wild eels, a field sampling study was carried out in a river. Five eel liver MT isoforms proved to contain Cd, Cu and Zn, while an additional MT form (or a complex with an isoform having different metal stoichiometry), absent in the aquarium samples, did not contain Cu. The quantitative results obtained indicated, both in aquarium and wild conditions, the different preferences for metal sequestration of each eel liver MT. This information could be most valuable to assess the potential of eel liver MTs as biomarkers in environmental studies.

G proteins immunodetection and adrenergic transduction pathways in the liver of Anguilla anguilla.

G proteins are members of a highly conserved superfamily of GTPases, which includes heterotrimeric (alpha, beta, gamma) proteins acting as critical control points for transmembrane signaling. In ectothermal vertebrates, knowledge about these proteins is scarce, and our work provides the first demonstration that G(s), G(q), and G(i) proteins are all present in the liver of a fish. G(q)alpha subunits of about 42 kDa have been identified in European eel (Anguilla anguilla) liver membranes, supporting previous reports about the existence of hormone transduction pathways coupled to inositol 1,4,5-trisphosphate/Ca(2+) enhancement in fish hepatocytes. Although two G(s)alpha proteins of about 45 and 52 kDa have been reported in mammals, a single isoform of approximately 45 kDa has been recognized in eel liver. G(s)alpha and G(q)alpha proteins are involved in the epinephrine transduction pathway, leading to cAMP and Ca(2+) intracellular increments, respectively. Interestingly, both messengers significantly stimulated glucose release from eel hepatocytes but with a different time course. In fact, the Ca(2+)-dependent glucose output preceded the cAMP-mediated release by about 7 min. G(i)alpha subunits of about 40 kDa were also immunodetected, suggesting the presence of hormone receptors leading to adenylyl cyclase inhibition in eel liver; however, alpha(2)- adrenoreceptor ligands were ineffective on both enzyme activity and glucose release.

The mitochondrial tricarboxylate carrier of silver eel: dimeric structure and cytosolic exposure of both N- and C-termini.

The mitochondrial tricarboxylate carrier plays a fundamental role in the hepatic fatty acid synthesis. In this study, we investigated the transmembrane organization of this protein in the inner membrane of eel liver mitochondria using anti-N-terminal and anti-C-terminal antibodies. These antibodies recognized the N- and C-termini of the tricarboxylate carrier in intact mitoplasts, thus suggesting a cytosolic exposure of these regions in the membrane-bound protein. This structural arrangement of the tricarboxylate carrier was further confirmed by protease treatment of intact mitoplasts. Moreover, the oligomeric state of the native tricarboxylate carrier was investigated by blue native electrophoresis. A dimeric form of the carrier protein was found when eel liver mitochondria were solubilized with the mild detergent digitonin. These findings suggest an arrangement of the dimeric tricarboxylate carrier into an even number of membrane-spanning domains, with the N-terminal and C-terminal regions oriented toward the intermembrane space of fish mitochondria.

Butyltin and phenyltin compounds in eels (Anguilla anguilla)

Tributyltin (TBT) and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), together with triphenyltin (TPT), were investigated in eels from the Thames Estuary and the Weston Canal (Merseyside). Within individual eels, the concentrations of organotin (OT) compounds varied considerably between tissues. Tributyltin concentrations were highest in heart and gall bladder and lowest in muscle and gonad. Tributyltin was generally the most predominant of butyltin (BT) compounds present in eel tissues and DBT the least. Phenyltins were detected in eels from both locations, notably the Weston Canal where TPT was present up to 0.367 μg g−1 (as Sn) in liver samples. Concentrations of OTs in liver (and muscle) were independent of weight and length in the eel populations examined. In a survey of OTs in eel populations along the Thames Estuary hepatic TBT levels ranged from 0.066–0.347 μg g−1 dry wt (as Sn) in liver of eels and were generally highest in the mid-section of the estuary, resembling the distribution pattern of TBT in sediment. Proportions of TBT to total BTs were also elevated in eel from this section of the waterway, consistent with continuing inputs in this region, albeit at relatively low levels. Major sewage treatment plants are sited here and may represent a possible source.

Citrate carrier activity and cardiolipin level in eel ( Anguilla anguilla) liver mitochondria

The activity of the tricarboxylate (citrate) carrier has been assayed in intact liver mitochondria from yellow eel ( Anguilla anguilla) and compared to that from rat. The eel-citrate carrier specific activity was approximately 1.7-fold higher than that assayed in rat-liver mitochondria. The content of the main mitochondrial phospholipids, phosphatidylethanolamine and phosphatidylcholine, did not show a significant difference between the two species, while in eel a higher cardiolipin level was observed. Fatty acid composition of eel-liver mitochondrial phospholipids was characterised by a large amount of unsaturated fatty acids, dominated by octadecaenoic acid (C 18:1 n-9) and docosahexaenoic acid (C 22:6 n-3). The cardiolipin fatty acid pattern of eel-liver mitochondria showed, with respect to the rat, a higher C 20:5 n-3 and C 22:6 n-3 content and a lower amount of C 18:2 n-6 and C 20:4 n-6. A noticeable activity of lipogenic enzymes was also detected in eel liver cytosol. The results of this study suggest that the remarkable activity of the citrate carrier in eel-liver mitochondria can most likely be ascribed to a considerable cardiolipin level. A covariance of citrate carrier and lipogenic enzyme activities was observed.

Exposure screening of some aquatic animals to persistent pollutants on the Rhone river, France

The Rhone river is contaminated with nuclear, chemical, urban and agricultural wastes. This study is an investigation of the level of exposure to polychlorinated biphenyls (PCBs), radionuclides of top predators of this river, Great cormorant (Phalacrocorax carbo sinensis) and European eel (Anguilla anguilla). Low concentrations of PCBs were found in liver and muscle of cormorants and eels from the Rhone river in 2000 and in 2001 : the total PCBs contamination was about 2 µg/g lipid for both cormorants and eels from the Rhone river. All measurements of artificial radioactivity in cormorants from the Rhone river were below the detection limit. Two 7-ethoxyresorufin-O-deethylase (EROD) activity experiments on caged eels were conducted in the lower Rhone river. EROD activity was induced and could be correlated to persistent pollutants as PCBs or others dioxin-like pollutants, or polycyclic aromatic hydrocarbons (PAHs). These results suggest that cormorants and eels are at least, slightly contaminated with PCBs and not with artificial radionuclides, despite the high level of nuclearization of the valley.

Metallothionein in liver of eels Anguilla anguilla from the Thames Estuary: an indicator of environmental quality?

The purpose of this study was to examine the role of the cysteine-rich protein metallothionein (MT) in the detoxification and metabolism of metals in livers of eels Anguilla anguilla from the Thames Estuary, and to assess the value of MT measurements in environmental monitoring. Hepatic MT levels and associated metal concentrations were determined in A. anguilla collected on three occasions during 1998 at sites along the tidal Thames (from freshwater to the sea) and also from a reference site (Tamar Estuary) in southwest England. MT was present at basal levels of 2 mg g −1 dry weight (dw), predominantly in association with the essential metals Cu and Zn. MT concentrations were variable within each eel ‘population’ but were generally highest (up to 11 mg g −1 in individual eels) at the more contaminated upper- and mid-estuarine sites in the Thames (e.g. Brentford and Kew). Lowest MT levels were those in eels from Blythe Sands at the mouth of the estuary. Season, sex, reproductive status and salinity may have influenced MT levels to some extent, although metals were the most significant factor. Hepatic MT concentrations were highly correlated with associated metal burdens (Zn, Cu, Ag and Cd),—notably reflecting Cu and Ag enrichment in the upper- and mid-estuary. With the exception of Zn, metals in the supernatant fraction of eel livers were primarily associated with MT. Proportions of Cu, Ag and Cd bound to MT increased as a function of accumulated metal burdens, with no indication of saturation. Thus, despite causing induction of MT, excess bioavailable Cu, Ag and Cd appear to be successfully detoxified in eels over the range of environmental contamination encountered along the Thames Estuary. Paradoxically, it may be argued from conventional doctrine that the presence of raised levels of MT, at upstream sites, constitutes a response to contamination and, by definition, signals that the fish are affected by metals; however, obvious signs of deleterious effects were not detected. Superficially, from liver MT data, it would seem that eel populations have become biochemically adapted to metal contamination. The approach tested here has proved viable in helping to interpret trends in bioavailability and the toxicological significance of accumulated metal burdens in Thames eels. A. anguilla is a common inhabitant of estuarine and fresh waters throughout Europe, and related species occur world wide. Therefore, determination of hepatic MT (and associated metals) in eels could be useful for monitoring responses to metal exposure and environmental quality on a much broader basis. Ideally these determinations should be performed in tandem with other sublethal-effects measurements to maximise information.

High density lipoprotein binding protein of eel ( Anguilla japonica) liver with specificity of binding to apoAI as a ligand

High-density lipoprotein (HDL) binding protein (HBP) was isolated from the microsomal fraction of eel liver homogenate by affinity chromatography with a HDL-column. After SDS-PAGE and blotting, HBP on the PVDF membrane was detected by FITC-labeled HDL and apolipoprotein AI (apoAI) as a ligand. HBP in the microsomal fraction was most abundant among microsomal, mitochondrial and cytosolic fractions. The HBP isolated by a HDL-column consisted of at least three proteins with low molecular weights of 18.5, 14.5 and 13.5 kDa; the main component was 14.5 kDa. These proteins are not products of protease digestion, as the procedure was carried out in the presence of protease inhibitors including ( p-aminophenyl) methansulfonyl fluoride, 4-(2-aminoethyl)-benzenesulfonyl fluoride, pepstatin A, E-64, bestatin, leupeptin, aprotinin and EDTA. The HBP specifically bound to FITC-apoAI and faintly bound or did not bind to FITC-apoAII. Furthermore, binding of HDL labeled with lipophilic fluorescence to isolated eel hepatocytes was inhibited by the antibody to apoAI, but not inhibited by the antibody to apolipoprotein AII (apoAII). These results strongly suggest that the HBP isolated from the microsomal fraction is present on the plasma membrane of eel liver and plays important roles for the lipid transport through the interaction with HDL.

Induction of Micronuclei in Eel (Anguilla anguilla L.) by Heavy Metals

Micronucleus test was performed in situ on eels (Anguilla anguilla) from river sites with different levels of heavy metal pollution (cadmium and mercury). Cadmium content in eel liver but not micronuclei averages in kidney were associated with cadmium content in sediments. Mercury content in liver was not significantly associated with mercury content in sediments. Both cadmium and mercury induced micronuclei expression in eels when injected, the concentration tested being 1.7 mg metal/kg body weight and the micronuclei induction being 2.64 and 2.35 micronuclei per 1000 cells for cadmium and mercury respectively. It was concluded that these heavy metals are genotoxic for European eel, that eel liver metal content is a sensitive indicator for environmental monitoring of cadmium pollution, and that the micronuclei scores in eels are not a sensitive method to detect heavy metals pollution in freshwater ecosytems.

Cloning, sequencing, and phylogenetic analysis of complementary DNA of novel cytochrome P-450 CYP1A in Japanese eel (Anguilla japonica).

Complementary DNA of cytochrome P-450 CYP1A, in addition to CYP1A1, has been isolated from Japanese eel (Anguilla japonica) liver treated with 3-methylcholanthrene. The cDNA contained a 5' untranslated region of 66 bp, an open reading frame of 1554 bp coding for 517 amino acids and a stop codon, and a 3' untranslated region of 1166 bp. The predicted molecular weight of the Japanese eel CYP1A was approximately 58.5 kDa. The nucleotide sequence exhibited identities with the reported CYP1A1 sequences of 77% for Japanese eel, 75% for rainbow trout, 72% for scup, plaice, and butterfly fish, and 71% for toadfish. The deduced amino acid sequence exhibited identities with the reported CYP1A1 sequences of 78% for Japanese eel, 77% for rainbow trout, 75% for scup, 74% for toadfish, 73% for plaice, and 72% for butterfly fish. The novel eel CYP1A obtained had less similarity to the other teleost CYP1A1 proteins (72%-78%) than that of the eel CYP1A1 (74%-80%). When compared with mammalian CYP proteins, the novel eel CYP1A was more similar to the CYP1A1 proteins (54%-56%) than to the CYP1A2 proteins (50%-53%). The phylogenetic tree of the teleost CYP1A genes constructed using the maximum likelihood method suggested that the novel eel CYP1A is ubiquitous among the Anguilliformes.

The novel sequences of major plasma apolipoproteins in the eel Anguilla japonica

cDNAs encoding major plasma apolipoproteins (apo) were cloned from the eel Anguilla japonica liver and their nucleotide sequences determined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that eel lipoproteins contain apolipoproteins of 28 kDa and 14 kDa as major components. Each of the two apolipoproteins showed two isoforms having different isoelectric points as demonstrated by two-dimensional electrophoresis. The two 28 kDa components had different N-terminal amino acid sequences, whereas the two 14 kDa components had an identical one. Then cDNA clones encoding these apolipoproteins were isolated from a cDNA library constructed from the eel liver. An acidic 28 kDa component (28 kDa-1) consisted of 259 amino acids including a putative signal peptide of 27 residues, whereas a basic 28 kDa component (28 kDa-2) was composed of 260 amino acids containing a putative signal peptide of 23 residues. The tandem repeating units, which are characteristic of apolipoproteins, for 28 kDa-1 showed 27.8% identity to that of porcine apoA-IV, although mammalian apoA-IV is about 40 kDa and much larger than 28 kDa-1. However, the repeating units of 28 kDa-2 showed 52.5% identity to that of Atlantic salmon apoA-I. The 14 kDa apolipoprotein consisted of 142 amino acids containing a putative signal peptide of 20 residues. It has a novel sequence differing from apolipoproteins of other vertebrates. The transcriptional expressions of 28 kDa-1, 28 kDa-2, and 14 kDa components were all restricted to the liver, except for the transcripts of 28 kDa-2 which were also slightly expressed in the intestine.