Looking
to the future, it is clear that a particular class of nuclear markers, referred to as
short tandem repeats (STR or microsatellites), may maximize cost:benefit ratio for most
aquatic selective breeding programs. Besides a large abundance throughout the genome of a
target species, microsatellites exhibit high levels of allelic variation. This means
that microsatellites confer more information per unit assay than other marker systems.
Microsatellite techniques are the choice of
genetic resistance mapping since they are highly polymorphic in nature and widely
dispersed throughout the genome. They can provide answers to paternity testing and
evaluation of polymorphism within groups undergoing selection even before resistance
mapping has been achieved.
There are literally hundreds of private
laboratories employing DNA-marker based technology serving agriculture and animal
husbandry industries. The commercial and industrial sectors don’t usually publicize
developments or results for competitive reasons. In some cases, defined strains of
organisms have been patented and represent tremendous R&D investments for these
companies. Marker technology has been around for only a few decades and the enormous
economic returns for such technology have made it available only to the larger players
within the industry. Recent developments for enrichment and cloning techniques, high-speed
digital scanners and mechanization of the sequencing process have all contributed to
reducing the cost for and increasing the speed and accuracy of marker detection and
identification. Developments in time and cost factors make marker technology available to
a wider spectrum of possible users within the aquatic industry.
Back to
top
What makes ASICo’s technology unique
is its ability to rapidly isolate and identify large numbers of useful
loci from highly enriched libraries. Genotyping costs are competitive with all
commercial laboratories; however, output time for bulk processing is much faster due to
the proprietary techniques incorporated for isolation and identification work. It is
from these libraries and associations that quantitative profile differences can be
detected in DNA structure, which delineate individual animals displaying the targeted
QTL’s of economic importance. Procedurally, it is the same approach that has typified
industry rapid development and growth in other commercial plant and animal sectors over
the last two decades.
While the long-term focus for using
microsatellites is to provide trait associated markers, other uses for this tool which
benefit the aquatic breeder are:
- Identification of individual animals (e.g., individuals in a
broodstock population.
- Determining relative genetic similarity (tracking
relatedness) between randomly selective animals.
- Identification of broodstock parents of post larvae or
juveniles.
- Identification of siblings and half-siblings in a
mixed-parentage spawn.
- Determination and quantification of in-hatchery selection
(relative success of different genotypes within the hatchery).
- Characterization and legal protection or tagging of family
lines (strains).
- Use as markers in Marker Assisted Selection (MAS) for
genetic traits of economic importance (growth rate, nutritional efficiency, disease
resistance, etc.).
- Identification of hatchery-produced animals raised in
broodstock ponds.
- Markers for specific genes in gene isolation programs.
This tool has also already been applied to identification
of released animals for enhancement programs, as markers in genome mapping programs, and
as markers for evidence in forensic applications. |
