ISSN:
1573-5117
Keywords:
Rotifera
;
Brachionusplicatilis
;
hormonal regulation
;
population growth
;
sexual reproduction
;
body size
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Eight vertebrate and invertebrate hormones were screened for theireffect on population growth, mictic female production, and body size of themarine rotifer Brachionus plicatilis. Growth hormone (GH) or human chorionicgonadotropin (HCG) at 0.0025–25 I.U. ml−1 andestradiol-17β (E2), triiodothyronine (T_3),20-hydroxyecdysone (20-HE), 5-hydroxytryptamine (5-HT), gamma-aminobutyricacid (GABA) or juvenile hormone (JH) at 0.05–50 mg l−1were added to 5-ml of Nannochloropsis oculata suspension (7×106 cells ml−1). From an initial densityof 1 individual ml−1, rotifers were cultured with hormones for48 hours in 22 ppt seawater at 25 °C, in darkness.Rotifers were counted and classified into female types and transferred to anew algal food suspension without hormone every other day until day 8 whenbody size was measured. Population growth was significantly higher intreatments exposed to GABA (50 mg l−1), GH (0.0025 and 0.025I.U. ml−1), HCG (0.25 and 2.5 I.U. ml−1), and5-HT (5 mg l−1). E2 caused a decrease inpopulation growth, whereas JH, 20HE, and T3 had no effect.Mictic female production was significantly higher at 0.05 and 0.5 mgl−1 JH and 0.05 and 5 mg l−1 5HT. GH (0.0025 and0.025 I.U. ml−1), E2 (50 mg l−1),GABA (0.5, 5 and 50 mg l−1), and 20-HE (0.05 mgl−1) treatments had significantly higher mictic femaleproduction only on day 8, 6, 4, and 6, respectively. T3 andhCG had no effect on mictic female production. Lorica length increased by9.6% and 4.4% in rotifers treated with JH (0.05 mgl−1) and GABA (5 mg l−1), respectively. Correspondingly, lorica width increased by 8.9% and 2.6% inthese treatments. In comparison, 20-HE-, T3-, and HCG-treatedrotifers were smaller (3.9–8.2%) and GH, 5-HT andE2 had no effect on rotifer body size.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003124205002
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