ISSN 1022-7954, Russian Journal of Genetics, 2009, Vol. 45, No. 1, pp. 63–69. © Pleiades Publishing, Inc., 2009.
Original Russian Text © A.V. Korsunenko, A.V. Tyutin, S.K. Semyenova, 2009, published in Genetika, 2009, Vol. 45, No. 1, pp. 73–80.
RAPD markers are widely used to characterize the
within- and between-population diversity in various
animals and plants . In spite of several technical lim-
itations, RAPDs are still the only markers that are
employed in genome-wide typing of organisms with a
low DNA content . RAPD markers have been used
to estimate the intraspecies variation for many inverte-
brates, including parasitic worms trematodes [3–12].
Trematodes, or digenetic ﬂukes (Platyhelminthes:
Trematoda), are one of the most ancient groups of ﬂat-
worms that have a complex life cycle, which involves sev-
eral hosts and proceeds through several consecutive par-
thenogenetic and one hermaphroditic generations. Trema-
todes always infect various mollusks as the ﬁrst
intermediate host. In mollusks, parthenites (sporocysts or
rediae) are usually a progeny of one miracidium and form
a single clone  with the same genotype in all cercariae.
We have previously observed a clonal RAPD varia-
tion in digenetic ﬂukes of six families (Schistosoma-
tidae, Stirigeidae, Plagiorchiidae, Diplostomatidae,
Bucephalidae, and Gorgoderidae). The mean propor-
tion of polymorphic loci detectable with one primer for
cercariae originating from one sporocyst varied from
7.5 to 29.4% in the sporocystoidal trematodes exam-
ined . However, the estimates of genome variation
were obtained for cercariae collected from single
infected host mollusks.
In this work, we studied the clonal RAPD variation
cercariae isolated from three
freshwater mollusks (Bivalvia, Dreissenidae), which
were collected in two water reservoirs of the Volga
basin. This trematode is one of the most abundant
aboriginal ﬁsh parasites in the water reservoirs exam-
ined [15, 16]. To study the population structure, we
genetic diversity for
individual sporocysts, individual host mollusks, and
total mollusks from one or two water reservoirs.
MATERIALS AND METHODS
mollusks were collected in
August and September 2005 in the Gor’kovskoe Water
= 1) and two sites of the Rybinskoe Water
Reservoir, Koprino (
= 1) and Mologa (
= 1) in the
Volga basin (Yaroslavl oblast). The mollusks were col-
lected in the mainstream part of the reservoirs at a depth
of 5–10 m by the standard hydrobiological technique.
The distance between the Koprino and Mologa collec-
tion sites (upper Volga) was approximately 20 km; the
third collection site was in the lower region of the
Gor’kovskoe Water Reservoir (middle Volga), approxi-
mately 350 km south to the ﬁrst two sites.
Clonal and Population RAPD Variation of Cercariae Obtained
A. V. Korsunenko
, A. V. Tyutin
, and S. K. Semyenova
Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia;
Papanin Institute of Biology of Inland Water Bodies, Russian Academy of Sciences,
Borok, Yaroslavl Oblast, 152742 Russia
Received August 20, 2008
—Three arbitrary primers produced 114 RAPD markers for 37 cercariae from nine
sporocysts obtained from three
mollusks, which were collected in two water
reservoirs of the Volga basin. Analysis of the RAPD patterns established a unique genotype for each cercaria.
The topology of an UPGMA dendrogram did not reliably differentiate the cercaria according to the correspond-
ing sporocysts. However, three groups of genotypes were isolated and corresponded to the host mollusks, indi-
cating that each cercaria clone had a different genotype set. A within-sporocyst variation made the greatest con-
tribution (53.0%) to the total RAPD diversity, while the contributions of within-host and between-host varia-
tions to the total diversity were equal (23.5%). Cercariae isolated from two mollusks of the Rybinskoe Water
Reservoir were more similar to each other than to cercariae from the geographically distant Gor’kovskoe Water
Reservoir. Possible causes and distribution speciﬁcs of the observed genetic diversity of