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    • Article

      Effect of some vertebrate and invertebrate hormones on the population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis Müller 

      WG Gallardo, A Hagiwara, Y Tomita, K Soyano & TW Snell - Hydrobiologia, 1997 - Springer Verlag
      Eight vertebrate and invertebrate hormones were screened for their effect on population growth, mictic female production, and body size of the marine rotifer Brachionus plicatilis. Growth hormone (GH) or human chorionic gonadotropin (HCG) at 0.0025-25 I.U. ml-1 and estradio1-17β (E2), triiodothyronine (T3), 20-hydroxyecdysone (20-HE), 5-hydroxytryptamine(5-HT), gamma-aminobutyric acid (GABA) or juvenile hormone (JH) at 0.05-50 mg l-1 were added to 5-ml of Nannochloropsis oculata suspension (7 x 106 cells ml-1). From an initial density of 1 individual ml-1, rotifers were cultured with hormones for 48 hours in 22 ppt seawater at 25 °C, in darkness. Rotifers were counted and classified into female types and transferred to a new algal food suspension without hormone every other day until day 8 when body size was measured. Population growth was significantly higher in treatments exposed to GABA (50 mg l-1), GH (0.0025 and 0.025 I.U. ml-1), HCG (0.25 and 2.5 I.U. ml-1), and 5-HT (5 mg l-1). E2 caused a decrease in population growth, whereas JH, 20HE, and T3 had no effect. Mictic female production was significantly higher at 0.05 and 0.5 mg l-1 JH and 0.05 and 5 mg l- 5HT. GH (0.0025 and 0.025 I.U. ml-1), E2 (50 mg l-1 ), GABA (0.5, 5 and 50 mg l-1), and 20-HE (0.05 mg l-1) treatments had significantly higher mictic female production only on day 8, 6, 4, and 6, respectively. T3 and hCG had no effect on mictic female production. Lorica length increased by 9.6% and 4.4% in rotifers treated with JH (0.05 mg l-1) and GABA (5 mg l-1), respectively. Correspondingly, lorica width increased by 8.9% and 2.6% in these treatments. In comparison, 20-HE-, T3-, and HCG-treated rotifers were smaller (3.9-8.2%) and GH, 5-HT and E2 had no effect on rotifer body size.
    • Article

      GABA, 5-HT and amino acids in the rotifers Brachionus plicatilis and Brachionus rotundiformis 

      WG Gallardo, A Hagiwara, K Hara, K Soyano & TW Snell - Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology, 2000 - Elsevier
      γ-Aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) have been shown to increase the reproduction of the Brachionus plicatilis (NH3L strain). In the present study, the endogenous presence of GABA and 5-HT in the rotifers B. plicatilis (NH3L and Kamiura strains) and Brachionus rotundiformis (Langkawi strain) were confirmed by dot blot immunoassay and high-performance liquid chromatography (HPLC). HPLC showed that GABA and 5-HT concentrations in the three rotifer strains range from 71 to 188 pmol/mg and from 12 to 64 pmol/mg, respectively. A total of 33 amino acids were also detected in B. plicatilis and B. rotundiformis, with glutamic acid, serine, glycine, taurine, threonine, alanine, arginine, proline, valine and isoleucine in high concentrations relative to other amino acids.