SOME NOTES ON THE CONTROL OF SEXUALITY IN THE ROTIFER ASPLANCHNA SIEBOLDI1

Abstract

A mictic female‐inducing material, in addition to α‐tocopherol, is present in the grass meal “ex Perth.” This material and α‐tocopherol have Rf values of 0.71 and 0.65 when chromatographed on thin layers of silica gel G in petroleum ether, diethyl ether, and acetic acid (70 : 30 : 1). The activity in this less polar material cannot be attributed to a tocopherol isomer. Gas‐liquid chromatographic analysis showed this active material to contain at least 12 components, The only detectable source of biological activity in the grass Poa annua, both when fresh and when dried at 115C for 4.3 hr, was α‐tocopherol. When stored by a laboratory window at 23C for 2 weeks, P. annua contained no detectable α‐tocopherol but did contain a biologically active material with an of 0.71. This material probably is the same as that with an Rf of 0.71 in the grass meal and may be derived from α‐tocopherol, possibly through some heat‐labile or enzymatic process. Suspended particulate detritus originating from the decomposition of fresh P. annua in distilled water for 2 weeks had an average dimension of 30.6 µm and contained biological activity with an Rf of about 0.65. Information on the ecology of mictic female production in both Asplanchna brightwelli and A. sieboldi is summarized and discussed. The activity of P. annua detritus suggests that autochthonous and allochthonous algal and higher plant material which in the living state is unavailable to these rotifers subsequently may become available as particulate detritus material and provide an important source of compounds that induce mictic females.