High water temperatures impair the reproductive ability of the pejerrey fish Odontesthes bonariensis: effects on the hypophyseal-gonadal axis
Physiological and Biochemical Zoology. 2008-11-01; 81(6): 898-905
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1. Physiol Biochem Zool. 2008 Nov-Dec;81(6):898-905. doi: 10.1086/588178.
High water temperatures impair the reproductive ability of the pejerrey fish
Odontesthes bonariensis: effects on the hypophyseal-gonadal axis.
Soria FN(1), Strüssmann CA, Miranda LA.
(1)Laboratorio de Ictiofisiología y Acuicultura, Instituto de Investigaciones
Biotecnológicas-Instituto Tecnológico de Chascomús (IIB-INTECH), Universidad
Nacional de General San Martín (CONICET-UNSAM), Buenos Aires, Argentina.
The aim of this research was to study how high water temperatures impair the
reproductive activity of pejerrey Odontesthes bonariensis, an inland-water
atherinopsid fish species from the pampasic region of Argentina. Adult pejerrey
of both sexes were kept under a control-temperature regime (19 degrees C) and two
experimental temperatures (23 degrees and 27 degrees C) for 8 d. The effect of
elevated temperature on the pituitary-gonad axis was analyzed in terms of the
expression of gonadotropin (GtH) subunits: follicle-stimulating hormone beta,
luteinizing hormone beta (LH-beta), glycoprotein hormone alpha, and GtH receptors
FSH-R and LH-R by semiquantitative reverse transcriptase polymerase chain
reaction, plasma levels of sexual steroids by radioimmunoassay, and reproductive
status by gonadal histology. The results of this work clearly indicate that short
periods of exposure to high water temperatures disrupt pejerrey reproduction.
This effect was observed in spawning activity, at the histological level, and in
the reduction of plasma estradiol in females and testosterone in males. The mRNA
levels of GtH subunits and GtH receptors generally decreased in proportion to the
increase in temperature for both sexes. However, the differences between groups
were statistically significant only for LH-beta and for FSH-R expression in
pejerrey females. Thus, the gonads of pejerrey appear to be the primary target of
high water temperature. Analysis of the air temperature in this region over the
past 40 yr indicated an increase of 1.74 degrees C in mean annual temperature.
This increase, coupled with the mechanism of high-temperature sensitivity shown
in this study, may be one of the reasons for the decline in pejerrey populations
observed in this region over recent decades.
PMID: 18922066 [Indexed for MEDLINE]