Hydrobiologia 298: 175-178, 1995.
D. Belk, H. 1. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
175
Influence of light, DMSO and glycerol on the hatchability of
Thamnocephalus platyurus Packard cysts
G. Murugan & H. J. Dumont
Laboratory of Animal Ecology, University of Ghent, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
Key words: Thamnocephalus, light, cyst hatching, dimethyl sulfoxide, glycerol
Abstract
Effects of two light intensities and different concentrations of dimethyl sulfoxide (DMSO) and glycerol on hydrated
cyst hatching in Thamnocephalus platyurus were studied. A maximum of 65±6% hatching was recorded within
seven days at 2500 lux continuous light regime. Hatching was at a minimum during the first two days, peaked
between the third and fourth days, and decreased thereafter. Hatching success was a function of duration of light
exposure. Eight percent of cysts hatched in the dark, while cysts exposed to 24 h light and subsequently incubated in
the dark showed 27±2% hatching. Hatchability was significantly increased (23%) in 0.0375% DMSO and 0.0125%
glycerol. Concentrations above 0.05% DMSO and 0.025% glycerol had no or a negative influence on hatching.
Since low concentrations of DMSO were non-toxic, apolar compounds like Ca2+ ionophore can be dissolved in
DMSO to study the role of Calcium in cyst hatching.
Introduction
Resumption of embryonic development in the resting eggs of anostracans requires exogenous stimuli.
Temperature and salinity are known to play important
roles in this process. Light also has profound effects
on the development of resting embryos of crustaceans
such as Daphnia (Pan cella & Stross, 1963; Shan,
1970), Eulimnadia antlei (Bishop, 1967; Belk, 1972),
Triops (Hempel-Zawitkowska, 1970), and Artemia
(Sorgeioos, 1973; Vanhaecke et al., 1981). Anostracan
cysts hydrated in the dark show a lower percentage
of hatching than light-hydrated ones (Sorgeioos, 1973;
Van der Linden et al., 1986; Mitchell, 1990). Even
different light intensities (Vanhaecke et al., 1981) and
the period of light exposure (Mitchell, 1990) have a
remarkable influence on cyst hatching success.
A previous study by Dumont et al. (1992) showed
that cyst hatching in T platyurus is amplified by calcium ionophore A23187. Calcium ionophore is normally applied, dissolved in DMSO or ethanol (Pressman et aI., 1976). Dumont et al. (op. cit.) preferred glycerol to dissolve ionophore assuming that
DMSO/ethanol might have toxic side-effects on the
developing embryo.
In this study, an attempt is made to understand
the influence of light-dark regimes, light intensities,
and of DMSO and glycerol on the hatching success of
hydrated T platyurus cysts.
Materials and methods
Dried cysts from a single stock were used in all experiments. In each experiment, 5 replicates of 50 cysts each
in 40 ml of aerated Cairns medium were maintained at
24.3± 1 dc. DMSO and glycerol were purchased from
Sigma Chemicals Inc.
A light intensity of 1500 lux was used, a) continuously, and b) at 12 h intervals. Continuous light of
2500 lux was also used. Hydrated cysts were exposed
to 4,8, 12, 16,24 h of light (2500 lux), and thereafter
incubated in continuous darkness.
Eight concentrations, viz., 0, 0.0125%, 0.025%,
0.0375%, 0.05%, 0.0625%, 0.125%, 0.1875% of
DMSO and glycerol, dissolved in Cairns medium,
were used to test their effect on hatching.
Hatched nauplii were recorded and removed at 24 h
intervals during 7 days. Hatchability was expressed as
D. Belk, H. 1. Dumont & G. Maier (eds), Studies on Large Branchiopod Biology and Aquaculture II.
© 1995 Kluwer Academic Publishers.
175
Influence of light, DMSO and glycerol on the hatchability of
Thamnocephalus platyurus Packard cysts
G. Murugan & H. J. Dumont
Laboratory of Animal Ecology, University of Ghent, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
Key words: Thamnocephalus, light, cyst hatching, dimethyl sulfoxide, glycerol
Abstract
Effects of two light intensities and different concentrations of dimethyl sulfoxide (DMSO) and glycerol on hydrated
cyst hatching in Thamnocephalus platyurus were studied. A maximum of 65±6% hatching was recorded within
seven days at 2500 lux continuous light regime. Hatching was at a minimum during the first two days, peaked
between the third and fourth days, and decreased thereafter. Hatching success was a function of duration of light
exposure. Eight percent of cysts hatched in the dark, while cysts exposed to 24 h light and subsequently incubated in
the dark showed 27±2% hatching. Hatchability was significantly increased (23%) in 0.0375% DMSO and 0.0125%
glycerol. Concentrations above 0.05% DMSO and 0.025% glycerol had no or a negative influence on hatching.
Since low concentrations of DMSO were non-toxic, apolar compounds like Ca2+ ionophore can be dissolved in
DMSO to study the role of Calcium in cyst hatching.
Introduction
Resumption of embryonic development in the resting eggs of anostracans requires exogenous stimuli.
Temperature and salinity are known to play important
roles in this process. Light also has profound effects
on the development of resting embryos of crustaceans
such as Daphnia (Pan cella & Stross, 1963; Shan,
1970), Eulimnadia antlei (Bishop, 1967; Belk, 1972),
Triops (Hempel-Zawitkowska, 1970), and Artemia
(Sorgeioos, 1973; Vanhaecke et al., 1981). Anostracan
cysts hydrated in the dark show a lower percentage
of hatching than light-hydrated ones (Sorgeioos, 1973;
Van der Linden et al., 1986; Mitchell, 1990). Even
different light intensities (Vanhaecke et al., 1981) and
the period of light exposure (Mitchell, 1990) have a
remarkable influence on cyst hatching success.
A previous study by Dumont et al. (1992) showed
that cyst hatching in T platyurus is amplified by calcium ionophore A23187. Calcium ionophore is normally applied, dissolved in DMSO or ethanol (Pressman et aI., 1976). Dumont et al. (op. cit.) preferred glycerol to dissolve ionophore assuming that
DMSO/ethanol might have toxic side-effects on the
developing embryo.
In this study, an attempt is made to understand
the influence of light-dark regimes, light intensities,
and of DMSO and glycerol on the hatching success of
hydrated T platyurus cysts.
Materials and methods
Dried cysts from a single stock were used in all experiments. In each experiment, 5 replicates of 50 cysts each
in 40 ml of aerated Cairns medium were maintained at
24.3± 1 dc. DMSO and glycerol were purchased from
Sigma Chemicals Inc.
A light intensity of 1500 lux was used, a) continuously, and b) at 12 h intervals. Continuous light of
2500 lux was also used. Hydrated cysts were exposed
to 4,8, 12, 16,24 h of light (2500 lux), and thereafter
incubated in continuous darkness.
Eight concentrations, viz., 0, 0.0125%, 0.025%,
0.0375%, 0.05%, 0.0625%, 0.125%, 0.1875% of
DMSO and glycerol, dissolved in Cairns medium,
were used to test their effect on hatching.
Hatched nauplii were recorded and removed at 24 h
intervals during 7 days. Hatchability was expressed as