February 2015
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32 Reads
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70 Citations
Toxoplasma gondii infection has previously been described to cause infected mice to lose their fear of cat urine. This behavioral manipulation has been proposed to involve alterations of host dopamine pathways due to parasite-encoded aromatic amino acid hydroxylases. Here, we report successful knockout and complementation of the aromatic amino acid hydroxylase AAH2 gene, with no observable phenotype in parasite growth or differentiation in vitro and in vivo. Additionally, expression levels of the two aromatic amino acid hydroxylases were negligible both in tachyzoites and in bradyzoites. Finally, we were unable to confirm previously described effects of parasite infection on host dopamine either in vitro or in vivo, even when AAH2 was over-expressed using the BAG1 promoter. Together, these data indicate that AAH enzymes in the parasite do not cause global or regional alterations of dopamine in the host brain, although they may locally affect this pathway. Additionally, our findings suggest alternative roles for the AHH enzymes in T. gondii since AAH1 is essential for growth in non-dopaminergic cells. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
![6-OHDA rapidly decreases mitochondrial movement in DA axons. A) Diagram of microdevice B) Axonal movement of mitochondria in control and 6-OHDA treated axons. DA-GFP cultures (Top panels) grown in microdevices and transduced with MitoDsRed2 (Middle panels) were imaged 30 minutes after treatment with 6-OHDA. Resulting kymographs are shown below. For additional clarity tracks of moving particles are depicted in the bottom panels: blue lines denote anterograde movement and red lines indicate retrograde trafficking. Scale bar indicates 10 μm. Quantification of C) moving mitochondria (n = 4–5 devices per group with 4–5 axons analyzed per device) and D) mitochondrial speeds. The latter were calculated as described [10] (n = 60–80 mitochondria per group). In C and D, data are represented as mean ± SEM, * + indicates p < 0.05 versus control and 6-OHDA in somal compartment.](https://www.researchgate.net/profile/Shelly-Sakiyama-Elbert/publication/262781334/figure/fig1/AS:196143490310144@1423775660192/6-OHDA-rapidly-decreases-mitochondrial-movement-in-DA-axons-A-Diagram-of-microdevice-B_Q320.jpg)
![6-OHDA rapidly decreases mitochondrial movement in non-DA axons. A) Axonal movement of mitochondria in control and 6-OHDA treated axons. Non-GFP positive axons (non-DA; Top panels) that were labeled with MitoDsRed2 (Middle panels) were selected for imaging 30 minutes after treatment with 6-OHDA. Resulting kymographs are shown below. For additional clarity tracks of moving particles are depicted in the bottom panels: blue lines denote anterograde movement and red lines indicate retrograde trafficking. Scale bar indicates 10 μm. Quantification of B) moving mitochondria in both anterograde and retrograde directions (n = 3–4 devices per group from with 3–5 axons analyzed per device) and C) mitochondrial speeds of motile mitochondria. The latter were calculated as described [10] (n = 90–120 mitochondria per group). In B and C, data are represented as mean ± SEM, *: indicate p < 0.05 versus control.](https://www.researchgate.net/profile/Shelly-Sakiyama-Elbert/publication/262781334/figure/fig2/AS:196143490310147@1423775660238/6-OHDA-rapidly-decreases-mitochondrial-movement-in-non-DA-axons-A-Axonal-movement-of_Q320.jpg)
