title: Biphasic and triphasic dose responses in zebrafish embryos to low-dose 150 kV X-rays with different levels of hardness.
abstract: The in vivo low-dose responses of zebrafish (Danio rerio) embryos to 150 kV X-rays with different levels of hardness were examined through the number of apoptotic events revealed at 24 h post fertilization by vital dye acridine orange staining. Our results suggested that a triphasic dose response was likely a common phenomenon in living organisms irradiated by X-rays, which comprised an ultra-low-dose inhibition, low-dose stimulation and high-dose inhibition. Our results also suggested that the hormetic zone (or the stimulation zone) was shifted towards lower doses with application of filters. The non-detection of a triphasic dose response in previous experiments could likely be attributed to the use of hard X-rays, which shifted the hormetic zone into an unmonitored ultra-low-dose region. In such cases where the subhormetic zone was missed, a biphasic dose response would be reported instead.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Hong Kong.
authors.forename: Eva Yi
authors.initials: EY
authors.lastname: Kong
authors.affiliation: Department of Biomedical Sciences, City University of Hong Kong, Hong Kong State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong bhcheng@cityu.edu.hk peter.yu@cityu.edu.hk.
authors.forename: Shuk Han
authors.initials: SH
authors.lastname: Cheng
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Hong Kong State Key Laboratory in Marine Pollution, City University of Hong Kong, Hong Kong bhcheng@cityu.edu.hk peter.yu@cityu.edu.hk.
authors.forename: Kwan Ngok
authors.initials: KN
authors.lastname: Yu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004625:Embryo, Nonmammalian / Q000528:radiation effects*; D005260:Female; D006244:Hardness; D008297:Male; D014965:X-Rays; D015027:Zebrafish / Q000196:embryology*