Mucosal immunoglobulins at respiratory surfaces mark an ancient association that predates the emergence of tetrapods

Gas-exchange structures are critical for acquiring oxygen, but they also represent portals for pathogen entry. Local mucosal immunoglobulin responses against pathogens in specialized respiratory organs have only been described in tetrapods. Since fish gills are considered a mucosal surface, we hypothesized that a dedicated mucosal immunoglobulin response would be generated within its mucosa on microbial exposure. Supporting this hypothesis, here we demonstrate that following pathogen exposure, IgT(+) B cells proliferate and generate pathogen-specific IgT within the gills of fish, thus providing the first example of locally induced immunoglobulin in the mucosa of a cold-blooded species. Moreover, we demonstrate that gill microbiota is predominantly coated with IgT, thus providing previously unappreciated evidence that the microbiota present at a respiratory surface of a vertebrate is recognized by a mucosal immunoglobulin. Our findings indicate that respiratory surfaces and mucosal immunoglobulins are part of an ancient association that predates the emergence of tetrapods

Differential characterization of emerging skin diseases of rainbow trout - a standardized approach to capturing disease characteristics and development of case definitions

Farmed and wild salmonids are affected by a variety of skin conditions, some of which have significant economic and welfare implications. In many cases, the causes are not well understood, and one example is cold water strawberry disease of rainbow trout, also called red mark syndrome, which has been recorded in the UK since 2003. To date, there are no internationally agreed methods for describing these conditions, which has caused confusion for farmers and health professionals, who are often unclear as to whether they are dealing with a new or a previously described condition. This has resulted, inevitably, in delays to both accurate diagnosis and effective treatment regimes. Here, we provide a standardized methodology for the description of skin conditions of rainbow trout of uncertain aetiology. We demonstrate how the approach can be used to develop case definitions, using coldwater strawberry disease as an example

Selective breeding of food size rainbow trout:Currentandfutureprospects

Rainbow trout (Oncorhynchus mykiss) are a valuable aquaculture production species in the USA where an average 25,000 tons per year of food size rainbow trout were produced during 1988- 2002. Clear Springs Foods, Inc., is one of the largest producers of aquacultured rainbow trout, producing 10,000 tons annually. Privately held by an employee owned trust, Clear Springs is a vertically integrated company from brood stock through egg production, feed manufacturing, farm operations, processing, and distribution. Clear Springs has a significant commitment to research and development. Selective breed- ing of rainbow trout is an important component of its R&D program. The current goals of the selective breeding program are to improve growth and disease resistance. To improve these traits, data are recorded on thousands of individuals each year. Growth data is collected at var- ious ages to determine which families and which individuals within each family have the best growth. To improve disease resistance, a portion of the progeny from each family are exposed to specific pathogens in a standardized challenge test. Currently, each family is tested for sur- vivability to infectious hematopoietic necrosis virus (IHNV) and Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease (CWD) and rainbow trout fry syndrome (RTFS). Selection to improve growth began when the breeding program was initiated. The average weight of the odd-year generation group increased from 660 g at 328 days of age in 1991 to 921 g at 301 days in 2003. The average weight of the even-year group increased from 620 g at 328 days in 1992 to 866 g at 301 days in 2004. Selection to improve IHN resistance started with the 1994 generation. Using a standardized challenge test, IHN mortality decreased 25.8% in the odd-year generation group and 29.7% in the even. Growth is a moderately heritable trait that can be changed rapidly and economically with traditional quantitative genetic techniques. Disease resistance has much lower heritability and is more difficult to change. Better knowledge of spe- cific and general disease resistance mechanisms in trout would aid the industry in improving future stocks