Quantification of the inflammatory responses to pro-and anti-inflammatory agents in Manila clam, Ruditapes philippinarum.

Inflammation is a form of innate immune response of living organisms to harmful stimuli. In marine bivalves, inflammation is a common defense mechanism. Several studies have investigated the morphological features of inflammation in bivalves, such as hemocyte infiltration. However, the molecular and biochemical responses associated with inflammation in marine bivalves remain unexplored. Here, we investigated changes in nitric oxide (NO) levels, cyclooxygenase 2 (COX-2) activity, and allograft inflammatory factor-1 (AIF-1) gene expression levels in hemolymph samples collected from Manila clam (Ruditapes philippinarum) exposed to pro- and anti-inflammatory substances. These included the pro-inflammatory agent lipopolysaccharide (LPS), and the nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen and diclofenac, all widely used in vertebrates. Our study showed that NO levels, COX-2 activity, and AIF-1 expression increased in response to the treatments with LPS and decreased in response to the treatments with NSAIDs in a concentration-dependent manner. These results suggest that the mechanism of inflammatory responses in bivalves is very similar to that of vertebrates, and we propose that inflammatory responses can be quantified using these techniques and used to determine the physiological status of marine bivalves exposed to biotic or abiotic stresses.

Synthesis and biological evaluation of phenyl-1H-1,2,3-triazole derivatives as anti-inflammatory agents.

Rapid and efficient synthesis of a phenyl-1H-1,2,3-triazole library enabled cost-effective biological testing of a range of novel non-steroidal anti-inflammatory drugs with potential for improved drug efficacy and toxicity profiles. Anti-inflammatory activities of the phenyl-1H-1,2,3-triazole analogs synthesized in this report were assessed using the xylene-induced ear edema model in mice. At least four analogs, 2a, 2b, 2c, and 4a, showed more potent effects than the reference anti-inflammatory drug diclofenac at the same dose of 25 mg/kg. To explore relationships between the structural properties of phenyl-1H-1,2,3-triazole analogs and their anti-inflammatory activities in xylene-induced ear edema, comparative molecular field analysis was performed, and pharmacophores showing good anti-inflammatory activities were identified based on an analysis of contour maps obtained from comparative molecular field analysis. The anti-inflammatory effect on the molecular level was tested by the expression of tumor necrosis factor-alpha induced COX-2 using Western blots. Because the addition of the analog 2c caused the expression change of TNF-α induced COX-2, the molecular binding mode between 2c and COX-2 was elucidated using in silico docking.

The kinetoplastid parasite Azumiobodo hoyamushi, the causative agent of soft tunic syndrome of the sea squirt Halocynthia roretzi, resides in the East Sea of Korea.

Mass mortality of the edible sea squirt Halocynthia roretzi since the 1990s in the southern and eastern seas of Korea has caused large economic losses. The disease is characterized by symptoms of initially softened and thinned tunics that eventually rupture. Thus, the disease is called soft tunic syndrome (STS); however, the causative agent in these regions is unknown. In the present study, two kinetoplastid organisms were isolated from STS sea squirts collected from culture farms in Tongyeong located in the East Sea of Korea. Phylogenetic analysis of 18S rRNA sequences identified these organisms as Azumiobodo hoyamushi and Procryptobia sorokini. These kinetoplastids were injected into healthy sea squirts and cultured at 15°C for 13days. Sea squirts injected with A. hoyamushi showed 100% STS whereas, P. sorokini did not induce disease, thereby confirming A. hoyamushi as the causative agent of STS. A. hoyamushi flourishes in vitro at 10-15°C, and dies at temperatures below 5°C or above 20°C. The optimum salinity level for growth is 30-35psu, and death occurs below 25psu. These optima coincide with marine temperature and salinity levels between March and June on the southern coasts of Korea, the period when the syndrome occurs at the highest frequency. The identification here of A. hoyamushi as the causative agent of STS and our findings regarding its optimum growth conditions should lead to methods for reducing the incidence of STS.

The effect of mistletoe, Viscum album coloratum, extract on innate immune response of Nile tilapia (Oreochromis niloticus).

The purpose of the present study was to evaluate the effect of dietary mistletoe extracts on non-specific immune response and disease resistance of Nile tilapia (Oreochromis niloticus) against Aeromonas hydrophila infection. Tilapia fingerlings were fed with a diet containing 0 mg as a control, 10 mg, 50 mg, and 200 mg mistletoe powder kg(-1) dry diet for 80 days. The immunological parameters, respiratory burst activity, lysozyme activity, alternative complement haemolysis activity (ACH(50)), and phagocytic activity of fish were investigated following 20, 40 and 80 days of feeding. Fish were challenged with A. hydrophila on 80 days after feeding and mortalities were checked over 10 days post-infection. The results show that fish fed with mistletoe extract exhibited an increase in activity in all immunological parameters (P < 0.05) compared to the control group depending on feeding periods and doses of mistletoe. Following challenge with A. hydrophila, 42% less survivability was observed in the control group than in other experimental diet groups. The highest survival rate (83%) was shown in the group fed with a 50 mg mistletoe kg(-1) diet. The results suggest that mistletoe enables tilapia to promote immunity and be more resistant to A. hydrophila infection.

Anti-oxidative status and hepatic enzymes following acute administration of diethyl phthalate in olive flounder Paralichthys olivaceus, a marine culture fish.

Although diethyl phthalate (DEP) is one of the most frequently used phthalates in solvents and fixatives for numerous industrial products, almost no research has been done on its biochemical toxicity in aquatic animals. Olive flounder (Paralichthys olivaceus), an important culture fish in far eastern Asian countries, were treated with intraperitoneal DEP at 0, 100, 300 or 900 mg/kg for three consecutive days and biochemical effects were assessed in the liver, kidney and serum 24 h after the final dosing. Measured parameters were mostly restricted to oxidative status and toxicity of the organs. In the hepatic tissue, there were significant increases in lipid peroxide (LPO) at 100mg/kg and above. Other hepatic parameters, which were examined, changed only after 900 mg/kg: reduced glutathione content (GSH), glutathione reductase activity (GR), glutathione peroxidase (GPx) activity increased; catalase (CAT) activity decreased. DEP also induced elevation in LPO levels at above 100 mg/kg in renal tissues; however, there was only a decrease in GR and glutathione S-transferase (GST) activities with DEP 900 mg/kg in contrast to the liver. Enzyme activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in hepatic tissues decreased in a dose-dependent manner in response to DEP at above 300 mg/kg. DEP at 300-900 mg/kg, although not uniform among parameters, caused increases in serum alkaline phosphatase (ALP), lactate dehydrogenase (LDH), AST, ALT activities and osmolality value, suggesting that DEP at these doses induced hepatic cell damage. The results indicate that 100-900 mg/kg DEP induced oxidative stress and the fish seemed to activate compensatory anti-oxidant systems to cope with the imposed substance on the liver. Such compensatory activation was not evident in the kidney. Overall, DEP was only weakly toxic to olive flounder in terms of oxidative and hepatic damage.

High parasite burden increases the surfacing and mortality of the manila clam (Ruditapes philippinarum) in intertidal sandy mudflats on the west coast of Korea during hot summer.

BACKGROUND: Over the past few decades, mass mortality events of Manila clams have been reported from several tidal flats on the west coast of Korea during hot summers. During such mortality events, once clams simultaneously surface, they fail to re-burrow, perishing within a week. The present study aimed to identify the possible causes of the mass mortality of this clam species by investigating the Perkinsus olseni parasite burden and immune parameters of surfaced clams (SC) and normal buried clams (NBCs) when sea water or sediment temperature in the study area varied from 25 °C to 34 °C from late July through mid-August 2015. RESULTS: We collected 2 groups of clams distributed within a 10-m2 area when a summer clam mortality event occurred around Seonyu-do Island on the west coast of Korea in 2015. The clams were collected 2 days after they surfaced on the sediment and still looked healthy without any gaping. The clams were transported to the laboratory, and we compared P. olseni infection intensity and cell-mediated hemocyte parameters between the NBCs and SCs. SCs showed significantly higher levels of P. olseni burden, lower condition index, and lower levels of cell-mediated immune functions than those of NBCs. CONCLUSIONS: Our study suggests that high P. olseni infection weakens Manila clams' resistance against thermal stress, causing them to surface. We surmise that the summer mass mortality of Manila clams on the west coast of Korea is caused by the combined effects of high P. olseni infection levels and abnormally high water temperature stress.

Starvation-induced Physiological Responses and RNA/DNA Ratios in Rock Bream, Oplegnathus fasciatus, and Olive Flounder, Paralichthys olivaceus.

In a 12-week experiment, the rock bream, Oplegnathus fasciatus, and olive flounder, Paralichthys olivaceus, were investigated to determine the effects of starvation on their physiological parameters. The protein and DNA contents of the starved fish were significantly higher than the initial values and those of the fed fish. The RNA contents and RNA/DNA ratios of the fed fish were significantly higher than those of the other groups (P<0.05). The hematocrit, hemoglobin, red blood cells (RBC), and mean corpuscular volume (MCV) of the fed rock bream were significantly higher than at baseline (P<0.05), whereas the mean corpuscular hemoglobin concentration (MCHC) of the fed fish was lower than at baseline (P<0.05). The hematocrit, hemoglobin, RBC, and MCHC of the starved group were significantly lower than the baseline values, whereas the MCV of the starved group was significantly higher than the baseline value (P<0.05). No significant difference in alanine aminotransferase was observed between the fed fish and baseline, whereas the starved fish value was significantly higher than the baseline value (P<0.05). There were no significant differences in cortisol levels. However, the glucose level in the fed group was significantly higher than the baseline level and that in the starved group was significantly lower than the baseline level (P<0.05).

Removal of two pathogenic scuticociliates Miamiensis avidus and Miamiensis sp. using cells or culture filtrates of the dinoflagellate Alexandrium andersonii.

Scuticociliatosis, which is caused by parasitic protistan pathogens known as scuticociliates, is one of the most serious diseases in marine aquaculture worldwide. Thus, elimination of these ciliates is a primary concern for scientists and managers in the aquaculture industry. To date, formalin and other toxic chemicals have been used as anti-scuticociliate agents, but issues regarding their secondary effects often arise. Consequently, development of safer methods is necessary. To find out a safe method of controlling scuticociliate populations in aqua-tanks or small-scale natural environments, cultures of 14 phototrophic dinoflagellates were tested to determine whether they were able to control populations of the common scuticociliates Miamiensis avidus and Miamiensis sp. isolated from Korean waters. Among the dinoflagellates tested, both cells and culture filtrates of Alexandrium andersonii effectively killed M. avidus and Miamiensis sp. The minimal concentration of cells and equivalent culture filtrates of A. andersonii to kill all M. avidus cells within 48h of incubation was ca. 2500 and 4500 cells ml-1, respectively; whereas those needed to kill all Miamiensis sp. cells were ca. 1000 and 4500 cells ml-1, respectively. It was estimated that 1m3 of the stock culture containing 20,000A. andersonii cells ml-1 could eliminate all M. avidus cells in 7m3 of waters within the aqua-tanks on land and all Miamiensis sp. cells in 19m3 of waters within 48h. None of the brine shrimp Artemia salina nauplii incubated with concentrations of 50-4500A. andersonii cells ml-1 for 24h was dead. Furthermore, none of the flounder Paralichthys olivaceus juveniles incubated with a mean concentration of ca. 2280A. andersonii cells ml-1 for 96h was dead. Therefore, A. andersonii cultures may be used as a safe biological method for controlling populations of scuticociliates and can replace toxic formalin. The results of this study provided the basis for developing the method to control scuticociliate populations and understanding interactions between scuticociliates and phototrophic dinoflagellates in marine ecosystems.

Alteration of hepatic anti-oxidant systems by 4-nonylphenol, a metabolite of alkylphenol polyethoxylate detergents, in Far Eastern catfish Silurus asotus.

OBJECTIVES: This study aimed to estimate the effects of 4-nonylphenol (NP), a ubiquitously present surfactant in aquatic environments, on the anti-oxidant systems of the liver in the Far Eastern catfish Silurus asotus. METHODS: Changes in biochemical parameters involved in glutathione (GSH)-related and other anti-oxidant systems were analyzed following 4 weeks of 4-NP administration (0.1 and 1.0 mg/kg diet) via a formulated diet to catfish. RESULTS: 4-NP exposure induced an elevation in hepatic lipid peroxide levels and an accompanying decrease in reduced state GSH after 2 weeks, suggesting pro-oxidant effects of the chemical in catfish. This oxidative stress was associated with an inhibition of the GSH-utilizing enzyme glutathione peroxidase at the same time point. This inhibition was restored after 4 weeks. The activities of other anti-oxidant enzymes, i.e., glutathione reductase, superoxide dismutase and catalase were increased after 4 weeks. These enzyme increases occurred more strongly at the higher 4-NP concentration (1.0 mg/kg diet). CONCLUSIONS: 4-NP given to catfish at 0.1 to 1.0 mg/kg diet, concentrations relevant to environmental levels, depletes the endogenous anti-oxidant molecule GSH and temporarily inhibits GSH-related anti-oxidant enzymes. Such declines in anti-oxidant capacity and elevated oxidative stress seem to be compensated eventually by subsequent activation of various anti-oxidant enzyme systems.

Effects of Prunella vulgaris labiatae extract on specific and non-specific immune responses in tilapia (Oreochromis niloticus).

We examined the effects of Prunella vulgaris Labiatae (P. vulgaris L.) on specific and non-specific immune responses of Nile tilapia, Oreochromis niloticus. The optimal concentration without toxicity of P. vulgaris was determined to 30-40 µg/ml in vitro and 120 µg/100 g of fish in vivo. P. vulgaris significantly elicited an antibody titer compared to FCA or ß-glucan. ß-glucan plus P. vulgaris group synergistically enhanced antibody production. No significant difference in antibody production was observed between P. vulgaris and P. vulgaris plus ß-glucan group. A respiratory burst activity of head kidney (HK) leucocytes of tilapia administered with 300 or 500 µg P. vulgaris was significantly (p < 0.05) enhanced compared with the PBS-injected control group and FCA-treated group. Maximum increase in the NBT reduction value was observed in 500 µg P. vulgaris group but no significant difference was found between 300 and 500 µg P. vulgaris group. The level of serum lysozyme activity was significantly (p < 0.05) higher in the 300 and 500 µg P. vulgaris than 100 µg P. vulgaris and FCA group. The phagocytic activities of HK leucocytes from tilapia administered with 300 and 500 µg P. vulgaris were significantly (p < 0.05) higher than 100 µg P. vulgaris and the control group. P. vulgaris was revealed with a good immunoadjuvant evoking the specific and non-specific immune responses of tilapia.

Quantitative assessment of Azumiobodo hoyamushi distribution in the tunic of soft tunic syndrome-affected ascidian Halocynthia roretzi using real-time polymerase chain reaction.

BACKGROUND: The kinetoplastid parasite, Azumiobodo hoyamushi, is the causative agent of soft tunic syndrome (STS) in ascidians and leads to their mass mortality in Korean waters. This study was conducted to quantify A. hoyamushi density during the development of STS in the tunics of ascidians (Halocynthia roretzi) using real-time polymerase chain reaction (qPCR). FINDINGS: The infection intensity of A. hoyamushi, as measured by qPCR, varied depending on the part of the tunic analyzed, as well as the stage of STS development. The highest infection intensity was recorded in the tunics of the siphons. The infection intensity of A. hoyamushi in the siphons was only 2.9 cell/tunic (area, 0.25 cm(2)) or 106.0 cell/gram tunic (GT) in the early phase of STS, but this value increased dramatically to 16,066 cells/tunic (0.25 cm(2)) or 617,004 cell/GT at the time of death. The number of A. hoyamushi parasites increased gradually and their distribution spread from the siphons to the other parts of the tunics. CONCLUSIONS: qPCR enabled the quantitation of A. hoyamushi and the results revealed that parasite density increased as STS progressed. In addition, our results suggested that the siphons might function as the portal of entry for A. hoyamushi during infection.

The Effects of Female Shell Size on Reproductive Potential of the Egg Capsule in Rapa Whelk Rapana venosa in Three Regions of Different Salinities.

We investigated the effects of shell height on reproductive potential of the female Rapana venosa in three regions of different salinities (the coastal zone of the Gwangyang Bay (S-1); the upper reaches (S-3); lower reaches (S-2) of the Seomjin River). The number of egg capsules, egg capsule height, and fecundity associated with reproductive potential of larger female rapa whelks were higher than those of smaller individuals in all three regions. Correlation analyses showed that there is a significant positive correlation between egg capsule and female shell height. Mean of shell heights, egg capsule heights, the number of egg capsules in an egg mass, and fecundity in an egg capsule produced from female individuals inhabiting S-1 region were markedly higher than those inhabiting S-2 and S-3 regions. In particular, the fecundity of the rapa whelk increased with the salinity and shell height. Although large rapa whelks produced a large number of egg capsules at S-1 region, those at S-3 habitat laid less egg capsules with smaller size. If these rapa whelks were put into S-2 region, the number of egg capsules produced by a female at S-2 region was slightly larger than those produced by a female at S-3 region. This provides a clear evidence that the number of the egg capsules can be controlled by the salinity. In the coastal zone of the Gwangyang Bay and the upper reaches of Seomjin River, the fecundity of this species was estimated to be approximately 182,000-1,302,000 eggs/ind./yr.

Four new species of Chryseobacterium from the rhizosphere of coastal sand dune plants, Chryseobacterium elymi sp. nov., Chryseobacterium hagamense sp. nov., Chryseobacterium lathyri sp. nov. and Chryseobacterium rhizosphaerae sp. nov.

The taxonomic positions of five Gram-negative, non-spore-forming and non-motile bacterial strains isolated from the rhizosphere of sand dune plants were examined using a polyphasic approach. The analysis of the 16S rRNA gene sequence indicated that all of the isolates fell into four distinct phylogenetic clusters belonging to the genus Chryseobacterium of the family Flavobacteriaceae. The 16S rRNA gene sequence similarities of isolates to mostly related type strains of Chryseobacterium ranged from 97.5% to 98.5%. All strains contained MK-6 as the predominant menaquinone, and iso-C(15:0), iso-C(17:0) 3-OH and a summed feature of iso-C(15:0) 2-OH and/or C(16:1) omega7c as the dominant fatty acids. Combined phenotypic, genotypic and chemotaxonomic data supported that they represented four novel species in the genus Chryseobacterium, for which the names Chryseobacterium hagamense sp. nov. (type strain RHA2-9(T)=KCTC 22545(T)=NBRC 105253(T)), Chryseobacterium elymi sp. nov. (type strain RHA3-1(T)=KCTC 22547(T)=NBRC 105251(T)), Chryseobacterium lathyri sp. nov. (type strain RBA2-6(T)=KCTC 22544(T)=NBRC 105250(T)), and Chryseobacterium rhizosphaerae sp. nov. (type strain RSB3-1(T)=KCTC 22548(T)=NBRC 105248(T)) are proposed.

Dietary Korean mistletoe enhances cellular non-specific immune responses and survival of Japanese eel (Anguilla japonica).

The present study was performed to investigate the immunostimulatory effects of Korean mistletoe extract (KM-110; Viscum album Coloratum) on the non-specific immune response and protection against Aeromonas hydrophila infection in Japanese eel (Anguilla japonica). Eels were fed under 4 regimes, 0%, 0.1%, 0.5% and 1.0% KM-110 mixed diet. On day 14 after feeding, 15 fish from each group were injected i.p. with live A. hydrophila (3 x 10(6)CFU) and the remaining unchallenged fish from each group were used to study the innate immune response. On 14 days post-infection, the total survival rates were 26.6% in control, and 33.3%, 66.6% and 80% in 0.1%, 0.5% and 1% KM-110-treated groups, respectively. The maximum lysozyme activity was observed in the 1% KM-110-treated group. There was no significant difference of lysozyme activity between 0.1% and 0.5% KM-110 group. Superoxide anion (O(2)(-)) production was significantly (p<0.05) augmented in the 0.5% and 1% KM-110 groups compared to the control and 0.1% KM-110 group. No significant difference of (O(2)(-) production was found between 0.5% and 1% KM-110 group. Likewise, there was a significant increase in phagocytic activity in the 0.5% KM-110 group compared with the 0.1% group (p<0.05), but no significant difference between the 0.5% and the 1% KM-110 group indicating that 0.5% KM-110 concentration is suitable for stimulating maximum phagocytic activity resulting in a high amount of ROI production. Considering the present results, KM-110 could be utilized as a promising immunostimulating substance for a diet in aquaculture.

Monitoring of streptomycin and dihydrostreptomycin residual levels in porcine meat press juice and muscle via solid-phase fluorescence immunoassay and confirmatory analysis by liquid chromatography after post-column derivatization.

A solid-phase fluorescence immunoassay (SPFIA) that was primarily developed for detection of antibiotic residues in milk was qualitatively applied for the pre-screening of the residues of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat press juice. The confirmation of both analytes was performed using a validated method of highperformance liquid chromatography with post-column derivatization. The analytical performance was demonstrated by the analysis of pork meat samples spiked at three concentration levels, ranging from 0.25 to 2.5 ppm for each analyte. In general, the recoveries ranged from 80.4 to 81.5% and from 79.6 to 84.4% for streptomycin and dihydrostreptomycin, respectively, with relative standard deviations lower than 6%. The limits of detection were 0.1 and 0.15 ppm for streptomycin and dihydrostreptomycin, respectively, and the limits of quantification of 0.35 and 0.5 ppm are below the maximum residue limits of Codex, the European Union, and the Korean Food and Drug Administration (ranging from 0.5 to 0.6 ppm). Eight real samples collected from the Seoul area were first monitored using SPFIA, and none of them were found positive. These findings are in good accordance with those observed by HPLC analysis. To the best of our knowledge, this is the first report to monitor the aminoglycoside residues in pork meat press juice using SPFIA.

A rat model to evaluate the pesticide permeability and stress effects of protective clothing.

No animal model exists for testing the suitability of a protective garment before actual application in humans. The animal testing model is valuable in particular as the assessment of permeability of hazardous chemicals in humans cannot be easily performed due to possible toxicity to test subjects. We explored a rat model by designing a protective garment to fit rats, and then examining pesticide permeability and physiological responses. When nongarmented rats were exercised in a treadmill, there were increases in heart rate, mean arterial pressure and body temperature. The increases in heart rate and body temperature were further augmented by wearing the protective garment. Fenitrothion, an organophosphate insecticide, was detected in plasma after application on the dorsal area in plasma of nongarmented and garmented (comparable to regular human work clothes) rats. Plasma acetylcholine esterase activity was decreased, suggesting intoxication in these animals. Fenitrothion intoxication was not observed in rats wearing a protective garment. In humans, heart rate and body temperature augmentation were also observed when wearing a protective garment. This result suggests that the present rat model provides a useful assessment of chemical permeability and stress effects of protective garments.

Effect of saikosaponin-A, a triterpenoid glycoside, isolated from Bupleurum falcatum on experimental allergic asthma.

The separation and isolation of an extract of Bupleurum falcatum were performed based on antiallergic activities in preliminary studies with higher plants. The final active compound was identified as saikosaponin-A (SSA), a triterpenoid glycoside. SSA at more than 1 mg/kg (i.v.) significantly inhibited the passive cutaneous anaphylaxis reaction in rats in a dose-dependent manner, attaining a maximum inhibition of approximately 60% with 10 mg/kg. SSA at 3 and 10 mg/kg also suppressed asthmatic bronchoconstriction in sensitized guinea-pigs. SSA possesses a weak inhibitory activity on histamine-induced tracheal contraction in guinea-pigs and on histamine release induced by A-23187 in rat mast cells. These results indicate that SSA has an inhibitory activity against allergic asthma. This activity seems to derive from both antagonism of the histamine action and inhibition of allergic mediators. Additional mechanisms may also be involved.

Antiallergic activity of a disaccharide isolated from Sanguisorba officinalis.

The antiallergic activity of the natural disaccharide, 5-O-alpha-D-(3-C-hydroxymethyl)lyxofuranosyl-beta-D-(2-C-hydroxymethyl)arabinofuranose was evaluated using both in vivo and in vitro experimental models. Intravenously administered compound inhibited the passive cutaneous anaphylaxis response in rats in a dose-dependent manner (ED(50) = 9.6 mg/kg). The compound inhibited histamine release evoked by both compound 48/80 and calcium ionophore A23187 in rat peritoneal mast cells indicating that mast cell stabilization is the major mechanism of action for its antiallergic activity. In passively sensitized isolated guinea-pig hearts, an in vitro anaphylaxis model in which histamine release plays a key role for functional deterioration, the compound markedly diminished both coronary flow reduction and histamine release on challenge to the antigen. These data demonstrate that this antiallergic natural disaccharide exerts its effect via inhibition of mast cell mediator release.

Cardiac responses of Pacific oyster Crassostrea gigas to agents modulating cholinergic function.

To examine the functional effects of cholinergic modulation compounds in oyster hearts and to explore their possible use in monitoring intoxication with acetylcholine-esterase (AChE) inhibitors such as organophosphates, tests were performed with in situ oyster heart preparations. The endogenous cholinergic agonist acetylcholine (ACh), AChE-resistant synthetic agonist carbachol, and the reversible carbamate type of AChE inhibitor physostigmine, all potently depressed spontaneous cardiac contractility. The depression was reversed by extensive washout, or prevented by muscarinic cholinergic antagonist atropine. The irreversible organophosphate type AChE inhibitor parathion or its active metabolite paraoxon at concentrations up to 100 microM failed to depress cardiac contractility. While other reversible AChE inhibitors such neostigmine and pyridostigmine also depressed the contractility, organophosphate AChE inhibitors malathion, diazinon, or phenthoate did not. Despite the differential effect in depressing cardiac function between the reversible and irreversible inhibitors, both of these inhibitors effectively inhibited cardiac AChE activity. The results suggest that the activation of muscarinic cholinergic receptors is coupled to inhibitory cardiac modulation, and organophosphate AChE inhibitors may inhibit only an AChE isozyme located at sites that are not important for control of cardiac activity in oysters.