Helicobacter delphinicola infection and the risk of gastric disease in common bottlenose dolphin.

Gastritis and gastric ulcers are well-recognized conditions in cetaceans; bacteria of the genus Helicobacter are considered the primary cause of these diseases. Dolphins have been shown to be susceptible to infection by at least 2 gastric species of Helicobacter, H. cetorum and H. delphinicola, both of which are closely related to the human pathogen H. pylori. In the present study, we evaluated the carriage rate and relationship to gastric disease of H. cetorum and H. delphinicola, based on a study population of 82 dolphins maintained at 21 facilities in Japan. Of these 82 dolphins, 79 (96.3%) and 45 (54.9%) were positive for H. cetorum and H. delphinicola, respectively; H. delphinicola infection was significantly associated with chronic gastric diseases (odds rate: 5.9; 95% CI: 2.1-16.9), but no such association was detected for H. cetorum. Of the 21 facilities, 20 (95%) and 11 (55%) housed H. cetorum- and H. delphinicola-positive dolphins, respectively, and our study suggested that the transmission between dolphins occurs quickly within pools. These findings indicate that methods will need to be established to prevent the transmission of Helicobacter infections within facilities housing dolphins.

Functions of post-conflict bystander affiliations toward aggressors and victims in bottlenose dolphins.

Post-conflict affiliations initiated by bystanders (bystander affiliation) toward aggressors or victims have been suggested to represent the function of conflict management in some social living species. However, the function of bystander affiliations toward aggressors and victims has not been examined in marine mammals. In the present study, we investigated the function of bystander affiliations to aggressors and victims in bottlenose dolphins: self-protection, the substitute of reconciliation, social facilitation and tension relief of opponents. These bystander affiliations did not reduce post-conflict attacks by former opponents against group members. Bystander affiliation to aggressors tended to be performed by a bystander who had an affiliative relationship with the aggressor but not with the victim. Bystander affiliation to victims also tended to be initiated by a bystander who had an affiliative relationship with the victim but not the aggressor and was close to former opponents at the end of aggressions. Affiliation among group members who stayed near former opponents during aggressions did not increase after aggressions compared to that under control conditions. Renewed aggressions between former opponents decreased after bystander affiliations in our previous study. Bystanders who showed social closeness to former opponents may initiate bystander affiliation toward their affiliative former opponents because they may feel emotion, such as anxiety and excitement, of former opponents. Bystander affiliation toward aggressors and victims may function as tension relief between former opponents. Bystanders of bottlenose dolphins, who may have a relaxed dominant style, might initiate post-conflict affiliation to affiliative individuals unaffected by the dominance relationships among them, unlike despotic species.

Seasonal changes in circulating gonadal steroid levels and physiological evidence for the presence of intrinsic circannual reproductive cycles in captive finless porpoises Neophocaena asiaeorientalis from the western Inland Sea, Japan.

We monitored annual fluctuations of gonadal steroid levels in three sexually mature captive finless porpoises (Neophocaena asiaeorientalis; two males and one female) from two different facilities over 56-91 months. Two animals (one male and one female) were held in an indoor tank with a sunroof (facility A) and the other male was held in an indoor tank without a sunroof (facility B). Water temperatures in both facilities reflected seasonal changes during the study period with a minor difference in the fluctuation pattern. Testosterone levels of the male in facility A were higher from spring to summer every year and exhibited a 12-month cycle. The female showed estrus cycles in 1-month intervals from summer to winter, excluding 2 anestrus years. In contrast, the period of higher testosterone levels of the male in facility B gradually initiated earlier over the years under a constant photoperiod (11.5L:12.5D) and exhibited a 9-month cycle during the first 52 months. After changing the light conditions to a natural photoperiod, its testosterone levels were high from early spring to summer for 3 consecutive years and exhibited a 12-month cycle. Our results showed that under a constant artificial photoperiod, the male in facility B failed to recognize the seasonal changes of a natural external environment, resulting in a 9-month, free-running hormone cycle.

Difference in Uptake of Tetrodotoxin and Saxitoxins into Liver Tissue Slices among Pufferfish, Boxfish and Porcupinefish.

Although pufferfish of the family Tetraodontidae contain high levels of tetrodotoxin (TTX) mainly in the liver, some species of pufferfish, boxfish of the family Ostraciidae, and porcupinefish of the family Diodontidae do not. To clarify the mechanisms, uptake of TTX and saxitoxins (STXs) into liver tissue slices of pufferfish, boxfish and porcupinefish was examined. Liver tissue slices of the pufferfish (toxic species Takifugu rubripes and non-toxic species Lagocephalus spadiceus, L. cheesemanii and Sphoeroides pachygaster) incubated with 50 µM TTX accumulated TTX (0.99-1.55 µg TTX/mg protein) after 8 h, regardless of the toxicity of the species. In contrast, in liver tissue slices of boxfish (Ostracion immaculatus) and porcupinefish (Diodon holocanthus, D. liturosus, D. hystrix and Chilomycterus reticulatus), TTX content did not increase with incubation time, and was about 0.1 µg TTX/mg protein. When liver tissue slices were incubated with 50 µM STXs for 8 h, the STXs content was <0.1 µg STXs/mg protein, irrespective of the fish species. These findings indicate that, like the toxic species of pufferfish T. rubripes, non-toxic species such as L. spadiceus, L. cheesemanii and S. pachygaster, potentially take up TTX into the liver, while non-toxic boxfish and porcupinefish do not take up either TTX or STXs.

Post-conflict affiliation as conflict management in captive bottlenose dolphins (Tursiops truncatus).

Post-conflict affiliation between former opponents or between one of the former opponents and bystanders might have the function of conflict management, which reduces the costs associated with aggressions. One of the suggested functions of post-conflict affiliation is decreased renewed aggressions directed from aggressors to victims. However, the effect of post-conflict affiliation on renewed aggressions by victims has not been investigated. We examined whether post-conflict affiliations decreased the number of renewed aggressions initiated by winners or losers in captive bottlenose dolphins. Both winners and losers initiated renewed aggressions. However, these aggressions decreased after post-conflict affiliation between former opponents, initiated by bystanders to winners, initiated by losers to bystanders, and initiated by bystanders to losers. Post-conflict affiliation between former opponents is suggested to function as reconciliation. Post-conflict affiliation initiated by losers to bystanders is suggested to function as the protection of losers. Post-conflict affiliations initiated by bystanders to one of former opponents are suggested to function as both appeasement and protection of the opponent who affiliates with bystanders.

Blocking of monocyte chemoattractant protein-1 (MCP-1) activity attenuates the severity of acute pancreatitis in rats.

BACKGROUND: Monocyte chemoattractant protein-1 (MCP-1) has been shown to affect the progression of various inflammatory disorders, including pancreatitis. To investigate the role of MCP-1 in acute pancreatitis and to seek possible therapeutic means, we evaluated the effect of a plasmid expression vector containing a dominant-negative mutant MCP-1 gene (mMCP-1). METHODS: Two rat models of acute pancreatitis were employed that used either cerulein (for mild pancreatitis) or a mixture of 5% taurocholic acid and trypsin (for severe pancreatitis). At 6 h after induction of acute pancreatitis with or without injection of mMCP-1, serum amylase levels and cytokine levels, as well as morphological evaluation of the pancreas, were determined. Survival rates were also evaluated. RESULTS: Severe pancreatitis was significantly reduced by mMCP-1 injection. mMCP-1 decreased serum levels of amylase, IL-6, IL-10, and LDH, and improved the survival rate 48 h after disease onset. Histopathological changes of pancreas and lungs were also improved by mMCP-1. CONCLUSIONS: MCP-1 appears to be involved in the progression of severe forms of acute pancreatitis. Our data suggested that MCP-1 is a candidate as a therapeutic target to treat acute pancreatitis.