T (-)-Calyculin A site zebrafish are a new genetic model system to study Fragile X syndrome (FXS).Behavior Synapse Features in Fragile X SyndromeFigure 6. LTP was significantly reduced in fmr1 KO zebrafish. (A) The arrow indicates delivery of HFS. Insets are representative, superimposed, single sweeps before and after LTP induction in wild-type (n = 9) and fmr1 KO (n = 10) 25033180 zebrafish. (B) Summary of the averaged magnitudes of LTP. Bars correspond to the percentages of baseline PS amplitudes during the last 10 min. *p,0.05 compared with wild-type. doi:10.1371/journal.pone.0051456.gPrevious behavioral studies have demonstrated that fmr1 KO mice replicate many of the human behavioral features of FXS, including hyperactivity, learning deficits, impaired social interaction, and abnormal anxiety-related responses [14]. Furthermore, behavioral profiles are a critical first step toward understanding the function of fmr1. Here, we performed a series of behavioral analyses on the fmr1 KO zebrafish that included the light/dark test, the inhibitory avoidance test, and the open-field test to further characterize the consequences of the absence of FMRP. Interestingly, significant behavioral differences were detected in the light/dark test. Compared with wild-type fish, fmr1 KO fish had reduced anxiety-related responses in the light/dark test. Our results are remarkably consistent with previous studies [13,38,39,40,41] in which the loss of FMRP has been reported to be related to anxiolytic responses in mice. Moreover, fmr1 KO zebrafish show a significantly greater number of crossed lines in the lit compartment, which significantly contributed to locomotor activity. Thus, hyperactivity may be present in fmr1 KO zebrafish. Cognitive impairment is a common symptom of FXS CAL-120 patients and FXS mouse models. For instance, Liu et al. (2011) noted impaired inhibitory avoidance acquisition in the fmr1 KO mice [13]. Here, using an inhibitory avoidance test, we evaluated whether Fmr1 null mutant zebrafish exhibited learning and memory impairments. Consistent with the notion that FMRP is involved in certain types of learning and memory, we 1081537 found a significant impairment in the inhibitory avoidance (IA) task in fmr1 KO fishes. These results suggested that the absence of FMRP might disrupt the detection abilities of and/or the response of the brain’s fear system. After the retention test in the IA task, theanimals were subjected to an open-field test; activity in the openfield is often used as a measure of exploration in zebrafish. The distance traveled and the mean speed in the open-field task was significantly higher in fmr1 KO fishes. Our behavioral analyses of the fmr1 KO fish in the light/dark and open-field tests supports previously reported results [13,14,39], suggesting that the absence FMRP expression leads to hyperactivity or increased exploratory behavior. According to neuroanatomical and behavioral analyses, the telencephalic pallium 
is a key component of the fear circuitry of teleost fish. For example, goldfish with lesions to the telencephalon have impaired avoidance conditioning [42,43]. In a previous study, we reported that the physiological function of the telencephalon is involved in the process of fear memory formation in inhibitory avoidance tasks in zebrafish [34]. Furthermore, electrophysiological evidence has demonstrated that the intratelencephalic connections between the lateral and medial pallium, and the Dl-Dm synapse, play important roles in the synaptic plasti.T zebrafish are a new genetic model system to study Fragile X syndrome (FXS).Behavior Synapse Features in Fragile X SyndromeFigure 6. LTP was significantly reduced in fmr1 KO zebrafish. (A) The arrow indicates delivery of HFS. Insets are representative, superimposed, single sweeps before and after LTP induction in wild-type (n = 9) and fmr1 KO (n = 10) 25033180 zebrafish. (B) Summary of the averaged magnitudes of LTP. Bars correspond to the percentages of baseline PS amplitudes during the last 10 min. *p,0.05 compared with wild-type. doi:10.1371/journal.pone.0051456.gPrevious behavioral studies have demonstrated that fmr1 KO mice replicate many of the human behavioral features of FXS, including hyperactivity, learning deficits, impaired social interaction, and abnormal anxiety-related responses [14]. Furthermore, behavioral profiles are a critical first step toward understanding the function of fmr1. Here, we performed a series of behavioral analyses on the fmr1 KO zebrafish that included the light/dark test, the inhibitory avoidance test, and the open-field test to further characterize the consequences of the absence of FMRP. Interestingly, significant behavioral differences were detected in the light/dark test. Compared with wild-type fish, fmr1 KO fish had reduced anxiety-related responses in the light/dark test. Our results are remarkably consistent with previous studies [13,38,39,40,41] in which the loss of FMRP has been reported to be related to anxiolytic responses in mice. Moreover, fmr1 KO zebrafish show a significantly greater number of crossed lines in the lit compartment, which significantly contributed to locomotor activity. Thus, hyperactivity may be present in fmr1 KO zebrafish. Cognitive impairment is a common symptom of FXS patients and FXS mouse models. For instance, Liu et al. (2011) noted impaired inhibitory avoidance acquisition in the fmr1 KO mice [13]. Here, using an inhibitory avoidance test, we evaluated whether Fmr1 null mutant zebrafish exhibited learning and memory impairments. Consistent with the notion that FMRP is involved in certain types of learning and memory, we 1081537 found a significant impairment in the inhibitory avoidance (IA) task in fmr1 KO fishes. These results suggested that the absence of FMRP might disrupt the detection abilities of and/or the response of the brain’s fear system. After the retention test in the IA task, theanimals were subjected to an open-field test; activity in the openfield is often used as a measure of exploration in zebrafish. The distance traveled and the mean speed in the open-field task was significantly higher in fmr1 KO fishes. Our behavioral analyses of the fmr1 KO fish in the light/dark and open-field tests supports previously reported results [13,14,39], 
suggesting that the absence FMRP expression leads to hyperactivity or increased exploratory behavior. According to neuroanatomical and behavioral analyses, the telencephalic pallium is a key component of the fear circuitry of teleost fish. For example, goldfish with lesions to the telencephalon have impaired avoidance conditioning [42,43]. In a previous study, we reported that the physiological function of the telencephalon is involved in the process of fear memory formation in inhibitory avoidance tasks in zebrafish [34]. Furthermore, electrophysiological evidence has demonstrated that the intratelencephalic connections between the lateral and medial pallium, and the Dl-Dm synapse, play important roles in the synaptic plasti.