Techniques to produce resistant lines of Pacific abalone, Haliotis discus discus, to amyotrophia disease

M. Hara (Genetic Div)


 To establish an evaluation method of genetic traits using mixed rearing in abalone, microsatellite DNA markers for pedigree analysis have been developed. It was shown that resistance to amyotrophia disease in juveniles of abalone is related to the genetic character of spawners using microsatellite DNA markers. This will be considered to contribute to the establishment of effective selection techniques and solutions of the problem of mass mortality during seed production in abalone called "Kuroawabi".


[Objective]
  Mass mortalities of juvenile abalone, Haliotis discus discus, have occurred frequently in many hatcheries. The development of resistant lines using selection techniques have been considered to be one of the effective methods. The aim of this research program is the establishment of an evaluation method of genetic traits using the microsatellite DNA markers for pedigree analysis. That is, the development of a method to estimate the genetic variation of abalone reared in the same rearing environment is goal. And, comparing with the families survived of the disease and the families produced by natural abalone, the resistant line have been attempted to be confirmed.

[Results]

  1. The 71 microsatellite DNA regions of abalone were isolated, and the variability and the Mendelian transmission of these regions were checked. 14 microsatellite DNA markers were developed as useful markers for pedigree analysis.
  2. In abalone seed that were mixed immediately after mating in one rearing tank, we were able to identify the pedigree completely.
  3. During mass mortalities of juvenile abalone that occurred from May to August, the composition of the seed produced by natural abalone were decreased largely, while that of the seed produced by parental abalone that had survived a previous infection by amyotrophia disease, increased remarkably. This suggested that the survied abalone had genetic resistance to amyotrophia disease, and were kept as breeding materials of the resistance.
  4. The analysis of parentage determination in hatcheries is expected to be an effective method for researching useful breeding materials.
[Publications]
1)M. Sekino and M. Hara (2001): Microsatellite DNA loci in Pacific abalone Haliotis discus discus. Molecular Ecology Note, 1, 8-10.
2)M. Hara and M. Sekino (2000): Genetic and breeding science of abalone and their application to the aquaculture techniques. SUISANZOSHOKU, 49(2), 123-126.

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