Figure 5 | Scientific Reports

Figure 5

From: Toxoplasma-induced changes in host risk behaviour are independent of parasite-derived AaaH2 tyrosine hydroxylase

Figure 5

Toxoplasma infection of mouse hosts results in abnormal reaction to trapping, independently of parasite TH. (A) Schematic representation of the trapping behavioural setup. Two boxes were connected by one transparent tunnel, with three access doors indicated in red and black (left panel). Trapping occurs when the doors indicated in red were closed. The right panel describes the protocol for the tunnel trapping test (see Methods). (B) Infected animals were faster in completing the tunnel test when compared to controls. (C) Control animals showed higher latencies to re-enter the tunnel after trapping had occurred whereas no such behaviour was observed in infected animals (left panel). The latencies for first (#1) tunnel entry were lower in infected animals relative to controls, with this difference being lost on the second (#2) tunnel entry. Similar latencies for entry #6 (which precedes trapping) were observed in all experimental groups. However, after trapping, infected animals did not show the increase in latencies for tunnel entry #7 (first entry after trapping), observed in control animals (right panel). (D) After the trapping time ended and doors opened, infected animals exited the tunnel faster than control animals. (E) All experimental groups displayed an increase in the time spent per cross after being trapped but infected animals were faster than controls in the first cross after the trapping event (entry #7). (F) The reduction in speed observed as a response to the trapping event remained unchanged by infection. (G) During the trapping period, infected animals moved forward more often than controls. Virtual spatial thresholds for scoring visits to the ends of the enclosed tunnel section are indicated by the dashed vertical lines. (H) Infection did not alter the number of times animals crossed the enclosed section midpoint, during the trapping period. (I) Over time analysis of the distribution of midpoint crosses during trapping showed a more uniform movement profile in animals infected with the wild type parasite strain. Profiles were divided in 2 min and 4 min periods (red line) defining early and remaining trapping periods. (J) The decrease in animal movement from early to remaining periods in trapping was present in all infected animal groups. (K) When trapped, infected animals showed a more uniform movement over time, as suggested by a ratio decrease. (B,C,E,F,HK) Mouse saline group, n = 11; TgWT group, n = 7; TgAaaH2KO group, n = 13. (D) Mouse saline group, n = 7; TgWT group, n = 6; TgAaaH2KO group, n = 9. (G) Mouse saline group, n = 8; TgWT group, n = 7; TgAaaH2KO group, n = 9. Dashed grey lines indicates trapping event. *p < 0.05. The data are presented as the mean ± SEM.

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