Fig 2. Adult sea lamprey behavioral responses to milt and spermine in a two-choice maze.
The index of preference (mean ± SEM) was calculated as the value of [Ae ÷ (Ae + Be)–Ac ÷ (Ac + Bc)], where Bc is the cumulative amount of time spent in the control channel before odorant application, Be is the cumulative amount of time spent in the experimental channel before odorant application, Ac is the cumulative amount of time spent in the control channel after odorant application, and Ae is the cumulative amount of time spent in the experimental channel after odorant application in a two-choice maze (S2 Fig; see Materials and methods). A positive index value indicates attraction, and a negative index value indicates repulsion. Significance was evaluated using a Wilcoxon signed-rank test. *p < 0.05. **p < 0.01. The number in the parentheses indicates the number of test subjects spending more time in the experimental channel out of the total sample size. Milt was applied to produce a final spermine concentration of (1) 2.2 × 10−14 M or (2) 3.8 × 10−14 M in the maze. Underlying data are available in S1 Data.