ISSN 1022-7954, Russian Journal of Genetics, 2008, Vol. 44, No. 7, pp. 833–840. © Pleiades Publishing, Inc., 2008.
Original Russian Text © K.I. Afanasiev, G.A. Rubtsova, M.V. Shitova, T.V. Malinina, L.A. Zhivotovsky, 2008, published in Genetika, 2008, Vol. 44, No. 7, pp. 956–963.
Chum salmon is one of the Paciﬁc salmon species.
It is widerspread in north Paciﬁc, ranks second in abun-
dance among Paciﬁc salmon from Sakhalin oblast
(region), and is commercially valuable species. Repro-
duction of chum salmon is provided both by natural
spawning and by artiﬁcial rearing in hatcheries. Simi-
larly to other salmonid species, the development of the
science-based strategy aimed at the increase of the
chum salmon reserves and its commercial harvesting
requires undestanding of the detailed population
genetic structure of the species [1–3].
At present, DNA markers, especially microsatel-
lites, are considered most promising for population
genetic analysis [4–7]. Investigation of microsatellite
variation in chum salmon is at its beginning. Based on
the microsatellite markers analysis, population struc-
ture was studied in chum salmon from some rivers of
North America, China, and Japan [8–11].
Detailed analysis of the chum salmon population
differentiation, performed for the ﬁsh spawning in the
rivers of Sakhalin Island  and for the chum salmon
for some water bodies of the Iturup Island, was initiated
in connection with the problems of distinguishing local
populations of this species . However similarly
detailed analysis of differentiation of the chum salmon
stocks in a considerable part of its distribution range in
the Russian Far East was never performed. In the
present study, based on microsatellite variation, genetic
differentiation of the chum salmon populations from
Sakhalin oblast was evaluated among the islands
(Sakhalin and Southern Kuril), as well as among the
rivers within island with consideration of intra-seasonal
and inter-annual variability.
MATERIALS AND METHODS
We used samples of spawners, collected during the
spawning run in 2003 through 2005 in the rivers and
hatcheries of Sakhalin, Iturup, and Kunashir
islands.The samples are listed in Table 1. Sampling
localities are shown in Fig. 1.
For DNA analysis, tissue samples (liver, muscles, or
pectoral ﬁn) were ﬁxed in 96% ethanol. Total DNA was
extracted using standard isolation procedure with the
Diatom DNA Prep reagent kit (IzoGen, Russia).
PCR ampliﬁcation was performed using the Gene
Pak PCR Core reagent kits (IzoGen, Russia), to which
l of primer mixture (ﬁnal concentration 0.5
l of DNA template (100 ng) were added. Ampli-
ﬁcation of microsatellite loci was carried out in MJ
Research PTC-100 thermal cycler. The reaction condi-
tions included eight cycles of DNA template denaturing
for 1 min; primer annealing for 30 s at
and extension at
for 30 s. Then followed 21 cycles
for 30 s;
for 30 s; and
for 15 s; ﬁnal
elongation for 3 min at
. The data on
annealing temperature for individual primer pair are
presented in Table 2.
Ampliﬁcation products were fractionated by means
of electrophoresis in 6% nondenaturing polyacryla-
mide gel in
TBE buffer  at 300 V for 2 to 3 h.
The gels were stained with ethidium bromide and pho-
tographed in the UV light. The 25-bp and 100-bp
molecular weight standards (Promega, United States)
and pBr322 plasmid DNA digested with the
restriction endonuclease were used as molecular
weight markers. Allele sizes for each locus were deter-
mined using the 1 D Image Analysis Software, version
Interregional Differentiation of Chum Salmon from Sakhalin
and South Kurils Inferred from Microsatellite Markers
K. I. Afanasiev, G. A. Rubtsova, M. V. Shitova, T. V. Malinina, and L. A. Zhivotovsky
Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia;
Received December 12, 2007
—Variability at ten microsatellite loci was examined in wild and hatchery populations of chum salmon
Walbaum) from the Sakhalin Island and Southern Kuril Islands, Iturup and Kunashir. Sub-
stantial genetic differences between Sakhalin and South Kurils chum salmon (the differentiation reached 6.0%)
were revealed. Statistically signiﬁcant differences between chum salmon from Iturup and those from Kunashir
were demonstrated, as well as between the chum salmon populations from different rivers within the islands. It
was shown that in different types of population comparisons, different marker sets were most informative.