Succession of the intestinal bacterial community in Pacific bluefin tuna (Thunnus orientalis) larvae.

We investigated the succession process of intestinal bacteria during seed production in full-cycle aquaculture of Pacific bluefin tuna (Thunnus orientalis). During the seed production, eggs, healthy fish, rearing water, and feeds from three experimental rounds in 2012 and 2013 were collected before transferring to offshore net cages and subjected to a fragment analysis of the bacterial community structure. We identified a clear succession of intestinal bacteria in bluefin tuna during seed production. While community structures of intestinal bacteria in the early stage of larvae were relatively similar to those of rearing water and feed, the bacterial community structures seen 17 days after hatching were different. Moreover, although intestinal bacteria in the late stage of larvae were less diverse than those in the early stage of larvae, the specific bacteria were predominant, suggesting that the developed intestinal environment of the host puts selection pressure on the bacteria in the late stage. The specific bacteria in the late stage of larvae, which likely composed 'core microbiota', were also found on the egg surface. The present study highlights that proper management of the seed production process, including the preparation of rearing water, feeds, and fish eggs, is important for the aquaculture of healthy fish.

Morphology of the oviduct fluke, Prosthogonimus ovatus, isolated from Indonesian native chickens and histopathological observation of the infected chickens.

Prosthogonimus ovatus infection was detected in 5 of 130 chickens in the oviduct and 4 chickens in the bursa of Fabricius. Scanning electron microscopy (SEM) revealed that the spines of the P. ovatus were densely distributed on the cuticula of the entire dorsal surface of body, but on the ventral surface, they were densely present to the level of ventral sucker but gradually decreased in density posteriorly, and they could not be seen in the posterior 1/3 area. The spines were finger-shaped and denticulate at the tip. Histopathological examination showed that polypous elevations, degeneration and exfoliation of the mucosal epithelium were detected in the bursa of Fabricius possibly by the suction of flukes, in addition to the stratification of the mucosal epithelium, and interstitial cell infiltration.