Hamid, Hafizah A (2015) A Role for Heme oxygenase-1 in Embryonic Development. PhD thesis, Victor Chang Cardiac Research Institute & Faculty of Medicine, UNSW Australia.
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Hafizah Hamid _PhD Thesis UNSW 2015.pdf Download (4MB) | Preview |
Abstract
Heme oxygenase-1 (HMOX1) is a stress-induced protein that degrades heme to carbon monoxide (CO), iron and biliverdin, which is subsequently reduced to bilirubin. HMOX1 deficiency is associated with decreased embryonic survival and previous studies report that exogenous CO attenuates this fetal loss. This PhD project aimed to determine: (i) the effects of HMOX1, O2 concentration and CO on in vitro development of pre-implantation embryos; (ii) the developmental stage at which HMOX1 deficiency impacts embryonic survival in vivo; and (iii) how HMOX1 deficiency may cause embryonic lethality in vivo. A new method for genotyping pre-implantation mouse embryos was first established to genotype pre-implantation mouse embryos obtained from Hmox1+/- x Hmox1+/- matings. In vitro culturing of pre-implantation embryos at varying O2 concentrations found wild-type blastocysts developed more efficiently in 6% O2 than in 1% or 21% O2. However, Hmox1–/– blastocysts developed normally irrespective of the O2 concentration used. Furthermore, using immunocytochemistry and bilirubin analysis, active HMOX1 was found to be present from zygote to blastocyst, co-localized with ferroportin 1 and increased under 1% and 21% O2. Additionally, exposure to 250 ppm CO decreased Hmox1+/+ and Hmox1 /– blastocyst development. In vivo embryonic survival was assessed by mating Hmox1+/– x Hmox1+/– mice, yielding 5.1% Hmox1–/– live births. Hmox1-/- embryonic survival followed expected Mendelian distribution up to E13.5 but significantly decreased at E14.5 to E19.5. At E13.5, morphological examination found Hmox1-/- embryos were smaller in size than Hmox1+/+ embryos, and preliminary histological examination suggested that Hmox1-/- embryos had disorganized trabeculation in their hearts, when compared to Hmox1+/+ and Hmox1+/- embryos. FACS analysis revealed Hmox1-/- fetal livers were contained fewer live cells but did not have defective erythroid and macrophage populations. At E14.5, Hmox1-/- embryos showed substantial necrosis. This PhD project presents in vitro and in vivo evidence to support a crucial role for HMOX1 in late, but not early, embryonic development. It demonstrates that HMOX1 is not essential for mouse embryonic development until E14.5. This study also reveals HMOX1 may play an important role in the embryonic development of the heart.
| Item Type: | Thesis (PhD ) |
|---|---|
| Additional Information: | Supervisor: Stocker, Roland, Victor Chang Cardiac Research Institute, Faculty of Medicine, UNSW. This work can be used in accordance with the Creative Commons BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). |
| Subjects: | R Medicine > R Medicine (General) |
| Depositing User: | Repository Administrator |
| Date Deposited: | 28 Apr 2016 06:22 |
| Last Modified: | 28 Apr 2016 06:28 |
| URI: | https://eprints.victorchang.edu.au/id/eprint/425 |
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