ISSN 10623604, Russian Journal of Developmental Biology, 2011, Vol. 42, No. 3, pp. 143–147. © Pleiades Publishing, Inc., 2011.
Original Russian Text © A.A. Bolotovskiy, B.A. Levin, 2011, published in Ontogenez, 2011, Vol. 42, No. 3, pp. 172–177.
Thyroid hormones (
) influence early devel
opment of fish. Manipulation with thyroid status of fish
makes it possible to accelerate or delay their ontogeny.
This causes shift in timing of organogenesis (Miwa and
Inui, 1987; Brown, 1997; de Jesus et al., 1998; Okada
et al., 2005). According to recent data, shift in timing can
cause formation of different states of morphological
characters in fish (Smirnov et al., 2006; Levin, 2010).
One of the important taxonomic characters in the sys
tematics of cyprinid fish (Cyprinidae) is the number and
arrangement of their pharyngeal teeth, which is called the
formula. It is known that, under hormonal changes of
ontogeny rate in large African barb
, the formula of pharyngeal teeth was highly vari
able (Smirnov and Levin, 2007; Shkil et al., 2010). And
these changes concerned not only the number of teeth
within each row but also the very number of teeth rows.
bream, the formula of pharyngeal
teeth is one row—5–5 (five teeth are on the left pharyn
geal bone and as many teeth are on the right pharyngeal
bone) (Reshetnikov, 2003), but sometimes tworow for
mulae can be found (Golubtsov and Il’in, 1983).
The goal of this article is to find out whether ontoge
netic rate influences changes in pharyngeal teeth formula
in the bream.
MATERIAL AND METHODS
Spawners were caught in the Rybinsk Reservoir, near
the Borok settlement (Yaroslavl oblast). Fertilization was
made with the help of a dry method on May 7, 2009. Ten
minutes after fertilization, the eggs were put in different
environments: (1) solution of exogenous triiodothyro
nine 1 ng/ml (TH group); (2) 0.015% thiourea solu
tion—a goitrogen, which blocks synthetic activity of thy
roid gland (THIO group); and (3) natural water
Before hatching occurred, the eggs were kept in the
crystallizer. Then, the fish larvae were moved into aquar
iums with the volume of 40 l and forced aeration. Aquar
ian conditions (temperature, oxygen, light regime, stock
ing density, feeding) were the same for all the experimen
tal groups. Approximately 1/3 of the water volume was
changed every day in order to maintain the concentration
of administrative substances within TH and THIO
groups. Fish were fed with zooplankton and dry feedstuff
for aquarium fish.
Fish were fixed in 4% formalin 2 months later after
the experiment began, when pharyngeal bones had
developed definitive dentition. Then, fish bones were
stained by alizarin red. When the staining was over, fish
were put into alkaline solution (KOH) for clearing. For
complete clearing, treatment, and further keeping, all the
examples were put into 100% glycerol.
Pharyngeal teeth and tissues surrounding them were
taken out of the whole mounts and examined with the
help of a Motic DM 143FBGG binocular. The pictures
of pharyngeal teeth were done with a Carl Zeiss LEO
1420 scanning electron microscope. Pictures of cleared
fish preparations were made with the help of a digital
camera for a SCOPETEK DCM510 microscope.
Influence of Development Rate on Pharyngeal Teeth Formula
(L.) Bream: Experimental Data
A. A. Bolotovskiy
and B. A. Levin
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742 Russia
Severtsov Institute of Ecology and Evolution, Leninskii pr. 33, Moscow, 119071 Russia
email: firstname.lastname@example.org, email@example.com
Received September 20, 2010; in final form December 28, 2010
—An experiment on acceleration and retardation of ontogeny with thyroid manipulation has
revealed direct changes in definitive dentition of pharyngeal bones in
bream. As development
rate accelerates, the number of teeth reduces to the formula 5–4. When development rate is retarded, this
number increases to the formula 6–5. Moreover, an additional minor row of teeth (1.6–5.1, 2.6–5.2) is
formed. The observed changes in tooth numbers exceed the known variability in natural populations of
bream. It is assumed that heterochronies lead to the changes in the number of teeth.
: thyroid hormones, goitrogen, fish, pharyngeal teeth, rate of development, Cyprinidae