The mucosal surfaces of wild and farmed aquatic vertebrates face the threat of many aquatic pathogens, including fungi. These surfaces are colonized by diverse symbiotic bacterial communities that may contribute to fight infection. Whereas the gut microbiome of teleosts has been extensively studied using pyrosequencing, this tool has rarely been employed to study the compositions of the bacterial communities present on other teleost mucosal surfaces. Here we provide a topographical map of the mucosal microbiome of an aquatic vertebrate, the rainbow trout (Oncorhynchus mykiss). Using 16S rRNA pyrosequencing, we revealed novel bacterial diversity at each of the five body sites sampled and showed that body site is a strong predictor of community composition. The skin exhibited the highest diversity, followed by the olfactory organ, gills, and gut. Flectobacillus was highly represented within skin and gill communities. Principal coordinate analysis and plots revealed clustering of external sites apart from internal sites. A highly diverse community was present within the epithelium, as demonstrated by confocal microscopy and pyrosequencing. Using in vitro assays, we demonstrated that two Arthrobacter sp. skin isolates, a Psychrobacter sp. strain, and a combined skin aerobic bacterial sample inhibit the growth of Saprolegnia australis and Mucor hiemalis, two important aquatic fungal pathogens. These results underscore the importance of symbiotic bacterial communities of fish and their potential role for the control of aquatic fungal diseases.T he mucosal surfaces of vertebrate animals are at the interface between the environment and the animal host. Mucosal epithelia form important mechanical and chemical barriers that prevent pathogen invasion but permit colonization by symbiotic microorganisms, the microbiota. The microbiota is crucial for the development, homeostasis, and immune function of an animal's mucosal epithelia (1, 2, 3).The associations between metazoans and commensal microorganisms are among the most ancient and successful associations found in nature (4, 5). The microbial communities of different organisms, such as plants, corals, annelids, gastropods, insects, and many vertebrates, are being characterized. In the particular case of vertebrates, mucosal surfaces have undergone drastic changes over the course of evolution due to the transition of vertebrate animals from water to land. These evolutionary pressures especially affected some mucosal barriers, such as the skin. While the skin of fish is a living cell layer that secretes a mucous layer and has imbricated scales for protection (6), amphibians have a cornified layer of skin that has developed into a more uniform epidermis (6). Finally, in birds and mammals, the presence of feathers, scales, hair, sweat glands, coats, or the leather-like thickening of the dermis represents unique adaptations to terrestrial environments. All these structures and appendages, in turn, provide unique niches within the skin for microbial colonization (6, 7).All verte...

Transportation of live fish is a common practice among aquaculture facilities. Many studies have previously reported how transport elicits physiological stress responses and increases disease susceptibility in farmed fish. The aim of this work is to investigate the changes that the skin of rainbow trout (Oncorhynchus mykiss) experiences due to stress. Since NaCl is commonly added to transport water as a stress mitigator, the effects of salt addition on the skin mucosa and skin-associated bacteria were also examined. Three experimental groups (Control, post-transport no salt (PTNS) and post-transport with salt (PTS)) were analyzed in a 5-hour transport acute stress model. Results indicate that the skin mucosa and the skin-associated bacteria are affected by transport stress. Total numbers of culturable skin-associated bacteria increased by ~10-fold and ~50-fold in the PTS and PTNS groups, respectively. Compared to controls, MUC2 expression was increased by 5-fold and 2-fold in the PTNS and PTS groups, respectively. Claudin-7, 8d and 12 expression levels were higher in both PTNS and PTS groups whereas antimicrobial peptide gene expression was lower than controls. Expression of the anti-inflammatory cytokine TGF-β but not IL-1β, IL-6 and TNF-α was up-regulated 2-3 fold in both the PTS and PTNS groups. The addition of salt diminished some of the physiological responses measured including the numbers of skin-associated bacteria. The responses recorded here appeared to be efficient at controlling bacterial translocation since stress did not lead to significant presence of bacteria in the liver or spleen of rainbow trout. When examining the ability of skin mucus to inhibit or promote growth of the bacterial pathogen Vibrio anguillarum, the skin mucus of PTS trout was more efficient at inhibiting V. anguillarum growth (20% inhibition) compared to control or PTNS mucus (11-12% inhibition). Our data clearly indicate the skin and skin microbiota of rainbow trout undergo important physiological responses during stress. The reduction in the magnitude of the skin responses recorded when salt was added to the transport water explains a new mechanism by which salt is an effective stress mitigator in some fish species. Aquaculture specialists will benefit from the present study by taking into consideration the importance of skin health during live transport.

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Culture and values are all too often ignored in the delivery of human services—a result that is frequently disastrous for American Indian recipients. This article examines some of the cultural aspects of rehabilitation and compares them with alternative values and cultures to demonstrate the need for change. It also describes the process of change that has already occurred on the Navajo reservation.