Introduction
Striped
catfish (Pangasianodon
hypophthalmus Sauvage, 1878) is a typical catfish in the
Pangasiidae family. It is a
migratory and benthic species with a natural origin in the Mekong River
and the Chao Phraya River basins (Ali et al, 2013). Due to fast growth,
high disease resistance and good adaptability to high density, it is
suitable for international intensive production, although it is now
predominantly cultured in Vietnam.
Influenced by trade and market requirements, striped catfish was
introduced to several other Asian
countries, such as Singapore, Philippines, Malaysia, India and China (De
Silva et al., 2006; Singh & Lakra, 2012). In view of burgeoning trade,
the introduction of striped catfish may boost up the aquaculture
production in some of these countries (De Silva et al., 2006; De Silva
& Soto, 2009). Currently, this
catfish species is widely cultured
in many Asian countries as an important food source
with a great economic
significance.
In a previous study, a primary assembly of striped catfish, based on
only Illumina short reads, was reported (Kim et al., 2018). In recent
years, combination of short reads, long reads and high-resolution
chromosome conformation capture (HIC) techniques has been widely
employed to improve the quality of many sequenced genomes (You et al.,
2020). In this study, we applied this integrated strategy to obtain a
chromosome-level genome assembly for the striped catfish with much
higher integrity and continuity values.
In addition to fish fillet, fish oil is also one of the important
value-added products with
unsaturated fatty acids.
Striped catfish has been
considered as an oily fish along
with other freshwater fishes from the Mekong sub-region, such as por
fish (Pangasius bocourti ), Mong fish (Pangasius
conchophilus ), and Mekong giant catfish (Pangasianodon gigas ;
Hemung et al., 2010). The
crude
fat from head and flab parts of striped catfish sums up to be 58.83%,
and unsaturated fatty acids in the crude fat account for 60.28% (Hemung
et al., 2010). Striped catfish therefore may be a considerable source of
unsaturated fatty acids for human consumption. However, for fish fillet,
the high fat content may have a negative impact on the economic value of
striped fishes (Van Sang et al., 2012). Hence, body fat of striped fish
has become an important trait for any practical breeding program.
By in-depth genomic analysis, we
observed
a tandem duplication of fatty acid binding protein 1 gene (fabp1 )
in the striped catfish genome. In fact, fabp1 is known to be
critical for fatty acid uptake and intracellular transport, and it also
plays an important role in regulation of lipid metabolism and cellular
signaling pathways (Furuhashi & Hotamisligil, 2008). Since fabp1was proved to be relevant to fatty acid storage, the tandem duplication
of fabp1 may be related to
the
high-fat trait of striped catfish.
It may provide a new perspective for molecular breeding of striped
catfish with an appropriate body fat content.