Dimethyl sulfoxide (DMSO), sodium hydroxide (NaOH), acetone, and ethanol which are commonly used as solvents for steroid and thyroid hormones were tested for their effect on rotifer population growth, mictic female production, and body size. Each chemical was tested at 0.2%, 0.4%, 0.6%, 0.8% and 1% of the 5-ml Nannochloropsis oculata suspension (7×10⁶cells/ml). Initially, 5 rotifers each carrying one amictic egg were exposed in these concentrations at 25℃ in dark condition for 48 hours. Thereafter, rotifers were counted and transferred to a new culture medium without the chemical on day 2, 4, 6, and 8. Body size was measured on day 8. DMSO at 0.2% and 0.4% significantly increased rotifer population growth while 0.4, 0.6, 0.8, and 1% caused an increase in mictic female production. NaOH at 0.4% and 0.8% significantly increased population growth while 0.8% caused an increase in mictic female production. Acetone at 0.8% and 1% caused a decrease in population growth but it had no effect on mictic female production. Ethanol caused a decrease in population growth in all tested concentrations but it did not affect mictic female production. Body size of DMSO-, NaOH-, acetone-, or ethanol-treated rotifers was not significantly different from that of the control. Acetone may be used as a solvent at concentrations lower than 0.8.%, whereas DMSO and NaOH may be used as high as 1% without adverse effects. Ethanol caused adverse effects as low as 0.2% and is therefore not suitable as solvent in experiments with rotifer populations.不溶性のステロイドホルモンや重金属化合物等の溶剤として用いられる,ジメチルスルホオキシド,水酸化ナトリウム,アセトン,エチルアルコール(ワムシ培養への添加濃度は各々0.2, 0.6, 0.8, 1.0%)が,ワムシの生殖特性とサイズにどのような影響を与えるか検討した。0.2%および0.4%DMSOの添加によってワムシの増殖は促進され,一方0.4%以上の濃度では両性生殖誘導率が高くなった。NaOHを0.4, 0.8%添加するとワムシ増殖率は高くなった。エタノールの添加はいずれの濃度でもワムシの増殖を阻害したが,0.6%以下のアセトン添加ではワムシの生殖特性に対する影響はみられなかった。いずれの溶剤もワムシのサイズに影響を与えることはなかった。以上の結果はワムシのホルモン作用や毒性評価試験の生物材料としてワムシを使用する場合の基礎知見となるものである
