Effect of juvenile hormone and serotonin (5-HT) on mixis induction of the rotifer Brachionus plicatilis Muller
Share
Abstract
Juvenile hormone (JH) and serotonin (5-HT) were previously shown to enhance mictic (sexual) female production of the rotifer Brachionus plicatilis in batch cultures. To explore the basis of these effects, experiments were conducted on isolated individuals. JH treatment of maternal rotifers with 5 and 50 µg ml-1 (18.8 and 187.7 µM) resulted in significantly higher (P < 0.05) mictic female production in the second (F2) and third (F3) generations. JH treatment was effective even at a lower food concentration of 7 × 105 cells ml, but it was not effective when free ammonia was added at 2.4 and 3.1 µg ml-1. Mictic female production was not increased with exposure to 5-HT up to 50 µg ml-1 (129.1 µM) concentrations. When food level was reduced to 7 × 105 cells ml-1, however, 5-HT-treated rotifers produced significantly (P < 0.05) more mictic females than the control, particularly in F3 generation. Mictic female production of 5-HT-treated rotifers did not differ from that of the control with or without free ammonia, but the intrinsic rate of natural increase (r) of 5-HT-treated rotifers at 3.1 µg ml-1 free ammonia was significantly higher than the control. These results show that juvenile hormone increases mictic female production under optimum and sub-optimum food levels, whereas 5-HT increases both mictic female production at low food level and population growth rate at high free ammonia concentrations. These compounds could be used to manage rotifer cultures and probe the mechanisms controlling the rotifer life cycle as it switches to mictic reproduction.
Suggested Citation
Gallardo, W. G., Hagiwara, A., & Snell, T. W. (2000). Effect of juvenile hormone and serotonin (5-HT) on mixis induction of the rotifer Brachionus plicatilis Muller. Journal of Experimental Marine Biology and Ecology , 252(1), 97-107. https://doi.org/10.1016/S0022-0981(00)00240-9
Type
ArticleISSN
0022-0981Collections
- Journal Articles [1266]
Related items
Showing items related by title, author, creator and subject.
-
Induction of sex inversion in juvenile grouper, Epinephelus malabaricus, (Bloch and Schneider) by bi-weekly injections of 17 alpha-methyltestosterone
; Garcia, Luis Maria
; (Society for the Study of Endocrinology, Metabolism and Reproduction, University of Hong Kong, 1989)
Groupers (Family Serranidae) are protogynous hermaphrodites. Natural sex inversion of different species occurs at 2-11 years of age . The scarcity of wild mature males and the length of time to change sex underline the need to do induced sex inversion studies. In Epinephelus tauvina and E. fario, sex inversion was successfully induced by oral administration of 17 alpha-methyltestosterone (MT). This paper reports on the induction of sex inversion of juvenile grouper E. malabaricus using bi-weekly intramuscular injections of MT. -
Control of gonad growth, maturation and spawning in teleost fish: A review
(Aquaculture Department, Southeast Asian Fisheries Development Center, 1996)Despite their great variety of reproductive strategies, a general characteristic of most teleosts is that (where known) natural reproduction shows a long-term periodicity, even in tropical habitats (e.g. see contributions in Munro et al. 1990a). Typically, gonad development from puberty leads to fully-grown gonads by the advent of the spawning season; if conditions are appropriate, then final gonad maturation leads to the production of viable gametes during one or more breeding bouts. Subsequently, in those larger species which spawn over more than one season, the gonads regress and the individual returns to a phase where any growth is somatic. However, there is wide interspecific variability in the pattern of gonad development (Wallace and Selman 1981, de Vlaming 1983, Billard 1986, Selman and Wallace 1989). -
Influence of LHRHa and methyltestosterone on milt production of sea bass Lates calcarifer (Bloch)
(Aquaculture Department, Southeast Asian Fisheries Development Center, 1996)Milt volume, sperm density, and number of spermatozoa were determined to quantify milt production of mature sea bass after a single injection of LHRHa [(D-Ala6,Pro9-N-ethylamiide)LHRH] in saline solution and 17α-methyltestosterone in corn oil (MT). Two measures of sperm density, sperm count and spermatocrit, were highly correlated (r=0.85). Compared with control, milt volume and the number of spermatozoa collected increased but sperm count decreased (24% at 24 h) after a LHRHa (20 µg/kg body weight treatment, suggesting a stimulation of spermatozoa production and not merely milt dilution. Further milt dilution (44%) was induced by 80 µg/kg LHRHa (LHRHa80) at 12 h post-treatment but not by 200 µg/kg MT (MT200) alone. A milt dilution of only 27% at 12 h after simultaneous injections of LHRHa80 and MT200 may indicate some inhibitory effect of MT on the efficiency of LHRHa. These results demonstrate that the stimulation of milt production by LHRHa involves testicular hydration resulting in milt dilution.
