Research ArticleBIOPHYSICS

Weak magnetic fields alter stem cell–mediated growth

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Science Advances  30 Jan 2019:
Vol. 5, no. 1, eaau7201
DOI: 10.1126/sciadv.aau7201
  • Fig. 1 WMFs alter planarian regeneration.

    (A) Composite image illustrating Schmidtea mediterranea amputation scheme. (B) Temporal analyses of 200 μT WMF exposure on anterior blastema size. Each row represents an experimental group of pharynx fragments that were exposed at the indicated times and scored at 3 dpa. The length of each bar is the duration of 200 μT exposure. Red bars, blastema inhibition (Student’s t test against 45 μT; P ≤ 0.05). Gray bars, no effect. n ≥ 12 for all conditions. (C and D) Blastema size following 200 μT exposure versus untreated and 45 μT controls. Arrowheads indicate presence (solid) or lack (open) of blastema. Scale bars, 200 μm. One-way analysis of variance (ANOVA) with Tukey’s multiple comparison test; n ≥ 24. (E) Blastema size following exposure to different field strengths. Student’s t test against 45 μT; n ≥ 16. Red bars, reduced blastema size. Green bar, increased blastema size. Gray bars, no effect. For all: **P < 0.01, ***P < 0.001, and ****P < 0.0001; error bars are SEM; anterior is up; and animals scored at 3 dpa.

  • Fig. 2 WMFs affect ROS levels during early regeneration.

    (A and B) Pharmacological ROS inhibition using 10 μM diphenyleneiodonium chloride (DPI) scored at 3 dpa. Student’s t test; n ≥ 20. Scale bars, 200 μm. DMSO, dimethyl sulfoxide. (C) Anterior ROS accumulation detection 1 hpa using the general oxidative stress indicator dye 5-(and-6)-chloromethyl-2′,7′-dicholorodihydrofluorescein diacetate (CM-H2DCFDA). One-way ANOVA with Tukey’s multiple comparison test; n ≥ 15. Scale bars, 200 μm. (D) RNAi of SOD imaged 3 dpa. Student’s t test against 45 μT; n ≥ 10. Scale bars, 100 μm. Red bar, reduced blastema size. Green bar, increased blastema size. Gray bar, no effect. For all: Solid arrowheads indicate normal blastemas; open arrowheads, lack of blastema; and double arrowheads, increased blastema; **P < 0.01 and ****P < 0.0001; error bars are SEM; and anterior is up.

  • Fig. 3 WMF effects on new tissue growth are caused by changes in both Hsp70 expression and proliferation.

    (A and B) Hsp70 RNAi scored at 3 dpa. Student’s t test; n ≥ 15. Arrowheads indicate presence (solid) or lack (open) of blastema. Control RNA: Venus-GFP. Scale bars, 200 μm. (C) Untreated intact animal whole-mount in situ hybridization (WISH) with the Hsp70 probe (n = 13). Scale bar, 200 μm. (D) Effects on Hsp70 expression visualized by WISH at 3 dpa. The anterior region is shown (n ≥ 5). Scale bars, 100 μm. (E) Phospho–histone H3 (pH3) staining of whole regenerates at 4 hpa. Only the anterior region is shown in the images. One-way ANOVA with Tukey’s multiple comparison test; n ≥ 6. Scale bars, 50 μm. For all: DPI used at 10 μM; **P < 0.01, ***P < 0.001, and ****P < 0.0001; error bars are SEM; and anterior is up.

  • Fig. 4 WMFs affect stem cell regulation during early regeneration.

    (A and B) Fluorescence in situ hybridization at 3 dpa to examine (A) the stem cell population (Piwi probe; n ≥ 6) and (B) stem cell differentiation (AGAT probe; n ≥ 5). The anterior region is shown. DPI used at 10 μM. Top panels are significantly different from bottom panels (Student’s t test; P ≤ 0.01). Scale bars, 50 μm. (C) Model for WMF effects on radical pair recombination. (D) Proposed pathway for 200 μT WMF effects on planarian regeneration.

Supplementary Materials

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Magnetic field enclosure (MagShield) setup.
    • Fig. S2. Loss of SOD rescues 200 μT WMF exposure by increasing levels of ROS.

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