INVESTIGADORES
MIRANDA Leandro Andres
artículos
Título:
Effects of daily water temperature fluctuations on brain-pituitray-gonad axis of pejerrey (Odontesthes bonariesnis) during its reproductive season
Autor/es:
MIRANDA LA; CHALDE T; ELISIO M
Revista:
Indian Journal of Science and Technology
Editorial:
Indian Society for Education and Environment
Referencias:
Lugar: Thrisur; Año: 2011 vol. 4 p. 38 - 39
ISSN:
0974-6846
Resumen:
The increases noted in the temperature of many water
bodies which are considered to be consequences of global warming have already
started to affect fish reproduction. Pejerrey is a multiple spawner and its reproductive
activity begins when water temperatures reach around 13 to15° C and peaks at
temperatures between 18 to 20° C with a major spawning period during spring. Recently, it has been demonstrated that constant temperature
regimes higher than 23° C impair pejerrey reproduction. In the last years, in shallow
lakes from pampasic region of Argentina (the natural habitat of O.
bonariensis), were reordered daily temperature fluctuations from 19° C to 27°
C during some days in spring. The aim of this study was to examine the effects of short-term pulses of
warm water on brain-pituitary-gonad axis of pejerrey during spawning season. Three
groups of 10 fish of both sexes with external signs of active reproductive
status were kept in tanks and subjected to constant 19° C (reproductive
control), daily temperature fluctuation from 19 to 25° C and from 19 to 27° C.
After 8 days, all fish were sacrificed and gene expression of brain GnRH
variants, pituitary GtH subunits (FSH-β, LH-β, GPH-α) and gonad GtH receptors
(FSH-R and LH-R) were analyzed by real-time quantitative PCR. Also, a portion
of the gonad of each fish was processed by routine histological
methods. Fish exposed to pulses of warm water stop to spawn and the histological
analysis of their testis and ovaries showed clear signs of regression. In
general, in those experimental fish it was observed that GnRHs, GtH subunits,
and GtH-Rs mRNA levels decreased when compared with fish from control group. However,
only pjGnRH (GnRH-I) and FSH-β in both sexes, LH-β and GPH-α in males and FSH-R
in females showed statistically significant differences. The results obtained
demonstrated that daily high water temperature fluctuations during spawning
season suppressed the gene expression of different genes in the brain-pituitary-gonad
axis blocking pejerrey reproduction.Global warming may increase the frequency of exposure
to harmful temperatures causing shortening or overall disruption of spawning
activity affecting pejerrey wild populations.