Sex-Inducing Activities of the Land Planarian Bipalium nobile Extract Fractions, Obtained Using Bioassay-Guided Fractionation, in the Freshwater Planarian Dugesia ryukyuensis

Sex-inducing effects toward planarians widely present among parasitic flatworms

“…However, a shift of the full sex-inducing effect to Fr. M30 under a new method, together with HPLC data from the present study and Kitamura et al., 22 collectively suggest that the substance responsible for full sex-inducing effects in B. nobile and C. calicophorum is likely the same compound eluting immediately after the tryptophan retention time in reverse-phase HPLC.

Figure 5 Sex-inducing substances eluted immediately after tryptophan (Trp) in reverse-phase HPLC (A) Fr.

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“…However, the results for C. calicophorum were consistent with a previous study on B. nobile that demonstrated the presence of a substance different from tryptophan with sex-inducing activity near the retention time of tryptophan. 22 There was no constantly detectable peak in Fr. M30-3-1 ( Figures 5 A and 5B), and the quantity of the responsible substance was not sufficient for structural estimation at this stage.…”

“…The sexualization process of the asexual OH worms can be roughly divided into six morphologically distinct stages ( Figure 1 B). 22 During stages one and two, the development of ovaries occurs, whereas other reproductive organs form during stages 3–6. 9 , 16 , 22 Between the second and third stages, there is a point of no-return that marks the capacity of the worm to autonomously complete the sexualization process without further administration of sex-inducing substances.…”

“… 22 During stages one and two, the development of ovaries occurs, whereas other reproductive organs form during stages 3–6. 9 , 16 , 22 Between the second and third stages, there is a point of no-return that marks the capacity of the worm to autonomously complete the sexualization process without further administration of sex-inducing substances. Here, we define sex-inducing substances as those capable of making the asexual OH worms go beyond the point of no-return, and the sex-inducing effects were evaluated based on whether the tested D. ryukyuensis worms developed copulatory organs ( Figure 1 B).…”

“…We, therefore, established a new purification method for sex-inducing substances, which overcomes the problem of conventional approaches where the fraction with sex-inducing activity contains a large amount of tryptophan. 22 , 27 First, a new large-scale purification method via open-column chromatography ( Figure S5 A) was established using the planarian Bipalium nobile , which has a large body size, easily ensuring the required amount of starting material for this method. With this method, the full sex-inducing effects observed in Fr.…”