disease resistance, and growth. Three hundred microsatellite markers each have
been isolated in three species of fish (rainbow trout, Atlantic salmon, and brown
trout) and used to draft genetic maps, with line analysis conducted to investigate
quantitative train loci (QLTs). Researchers in Spain and the U.S. are also conducting their own independent research on fish from the salmon family. DNA
marker isolation has been performed for pictus catfish and striped bass in the U.S.,
European carp in the Netherlands, and olive flounder in Japan to achieve variety
improvements (Bentzen et al. 1991; Hallerman and Beckmann 1988).
In the case of kuruma prawns (Australia and Thailand), isolation of
microsatellite markers is difficult. For breeding purposes, attempts are being made
to create a gene map for breeding applications using amplified fragment length
polymorphism (AFLP), although this approach is less generalizable than one using
microsatellite markers (Okamoto 2000).
The next section will focus on fish that are not being directly targeted for
breeding at present, but which have microsatellite markers that could potentially be
used for breeding in the future.
In the case of tilapia, U.S. researchers have isolated and reported around 60
microsatellite markers in an effort to explain separation and differentiation in
organisms in the cichlid tribe. Genetic map creation efforts are also under way.
Microsatellite markers have similarly been isolated for the European plaice (Spain),
oyster (Australian), Indian carp (India), red seabream (Japan), and ayu (also Japan).
Creating a genetic map involves large research costs, however, and maps cannot
be created for all species. In the case of livestock, commonality with markers can be
found in cattle, sheep, and goats. Similarly, effective map creation should be carried
out through examination of commonalities among markers from fish species.
To date, no reports have been published in academic journals on the discovery of
useful gene loci for marine organism breeding in line investigations using linkage
analysis. Similar findings in other areas, including human beings, are the focus of
great attention, and hopes for their discovery in the area of marine breeding are
high.
Isolation and stockpiling of markers and development of genetic maps are poised
to take place at a rapid rate in the future. Preparations are also being carried out for
analysis of genomes in rainbow trout and other fish from the salmon family. The
delay may simply be a matter of examining what traits consumers and producers
desire in their fish and where the fish possessing them live (or are being raised).
Fortunately, many research institutions in Japan have been developing clonal lines
for rainbow trout, olive flounder, and other fish, which are being used for marine
organism breeding. A broader investigation of their characteristics to identify the
markers linked to them through linkage analysis (line analysis) in assessing clonal
traits will soon allow the use of those markers to practically achieve varieties fixed
with only the target trait. Linkage analysis with DNA markers has also produced
significant results in marine breeding, and a global consensus will be necessary on
matters such as the scale of economic value from those results, as well as DNA
marker patenting issues.
5.7 New Marine Breeding with DNA Markers
139
been isolated in three species of fish (rainbow trout, Atlantic salmon, and brown
trout) and used to draft genetic maps, with line analysis conducted to investigate
quantitative train loci (QLTs). Researchers in Spain and the U.S. are also conducting their own independent research on fish from the salmon family. DNA
marker isolation has been performed for pictus catfish and striped bass in the U.S.,
European carp in the Netherlands, and olive flounder in Japan to achieve variety
improvements (Bentzen et al. 1991; Hallerman and Beckmann 1988).
In the case of kuruma prawns (Australia and Thailand), isolation of
microsatellite markers is difficult. For breeding purposes, attempts are being made
to create a gene map for breeding applications using amplified fragment length
polymorphism (AFLP), although this approach is less generalizable than one using
microsatellite markers (Okamoto 2000).
The next section will focus on fish that are not being directly targeted for
breeding at present, but which have microsatellite markers that could potentially be
used for breeding in the future.
In the case of tilapia, U.S. researchers have isolated and reported around 60
microsatellite markers in an effort to explain separation and differentiation in
organisms in the cichlid tribe. Genetic map creation efforts are also under way.
Microsatellite markers have similarly been isolated for the European plaice (Spain),
oyster (Australian), Indian carp (India), red seabream (Japan), and ayu (also Japan).
Creating a genetic map involves large research costs, however, and maps cannot
be created for all species. In the case of livestock, commonality with markers can be
found in cattle, sheep, and goats. Similarly, effective map creation should be carried
out through examination of commonalities among markers from fish species.
To date, no reports have been published in academic journals on the discovery of
useful gene loci for marine organism breeding in line investigations using linkage
analysis. Similar findings in other areas, including human beings, are the focus of
great attention, and hopes for their discovery in the area of marine breeding are
high.
Isolation and stockpiling of markers and development of genetic maps are poised
to take place at a rapid rate in the future. Preparations are also being carried out for
analysis of genomes in rainbow trout and other fish from the salmon family. The
delay may simply be a matter of examining what traits consumers and producers
desire in their fish and where the fish possessing them live (or are being raised).
Fortunately, many research institutions in Japan have been developing clonal lines
for rainbow trout, olive flounder, and other fish, which are being used for marine
organism breeding. A broader investigation of their characteristics to identify the
markers linked to them through linkage analysis (line analysis) in assessing clonal
traits will soon allow the use of those markers to practically achieve varieties fixed
with only the target trait. Linkage analysis with DNA markers has also produced
significant results in marine breeding, and a global consensus will be necessary on
matters such as the scale of economic value from those results, as well as DNA
marker patenting issues.
5.7 New Marine Breeding with DNA Markers
139