The starting point was the work of Embody and Hayford 1925 who increased

The starting point was the work of embody and hayford

This preview shows page 358 - 360 out of 594 pages.

The starting point was the work of Embody and Hayford (1925) who increased resistance in brook trout to furunculosis by selective breeding. Subsequently, Wolf
Image of page 358
340 Bacterial Fish Pathogens (1954) reported the start of an investigation aimed at developing ulcer disease and furunculosis-resistant strains of brook trout and brown trout. Five years later, Snieszko et al. (1959) concluded that disease was, indeed, genetically determined. Ehlinger (1964, 1977) echoed this opinion by determining resistance to furunculosis in the progeny of brook trout. Thereafter, a substantial leap forward in knowledge occurred following a publication by Cipriano (1982), who reported varying degrees of resistance to furunculosis among 11 different strains of rainbow trout, and correlated this with the serum neutralisation titre. Cipriano determined that the McConnaughy strain was the most susceptible, with 83% of the animals dying within 14 days of challenge with 1.2 x 10^ cells administered in a 1 min bath. The serum neutralisation titre was 1:80 against one of the extracellular fractions of Aer. sal- monicida. In contrast, there was no mortality among the Wytheville strain, which demonstrated a serum neutralisation titre of 1:2,560. Cipriano (1983) concluded that serum from rainbow trout (which are naturally resistant to furunculosis) could protect passively immunised brook trout from challenge with a virulent culture. In contrast, the administration of serum from susceptible Atlantic salmon was unsuc- cessful in conferring resistance upon brook trout. The protective effect of rainbow trout serum was believed to be attributed to the neutralisation of toxic components produced by the pathogen. Recent unpublished data have pointed to the ability of certain strains of rainbow trout to tolerate the rigours of furunculosis. Genetic variation in susceptibility of Atlantic salmon has been examined in the study of one-year-old fish (Gjedrem and Gjoen, 1995). Do resistant fish strains exist against other diseases? An affirmative response must be given as work has pointed to some strains of fish which are resistant to BKD (Suzumoto et al, 1977; Winter et al, 1979; Withler and Evelyn, 1990) and selective breeding enhances resistance to ERM and RTFS (Henryon et al, 2005). Studying comparative resistance to BKD in three juvenile coho salmon and steelhead trout strains (transferrin genotypes AA, AC and CC), it was found that the A A genotype was the most susceptible to BKD, whereas the CC genotype was the most resistant. Withler and Evelyn (1990) found a variation in resistance to BKD in two strains of coho salmon from British Columbia, Canada. In particular, survival was greater and the time to death was longer in juvenile animals from the Kitimat River strain than from the Robertson Creek strain. A similar approach has been used to investigate the control o^Edw. ictaluri infections in channel catfish, with data pointing to a difference in susceptibility according to genetic factors (Camp et al, 2000). Whereas both sensitive and resistant fish produced antibodies to Edw. ictaluri, the latter produced
Image of page 359
Image of page 360

You've reached the end of your free preview.

Want to read all 594 pages?

  • Spring '20
  • Bacteria, representative, gram-negative bacteria

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes
A+ icon
Ask Expert Tutors