SummaryAs discussed on the homepage, sufferers of osteogenesis imperfecta (OI) exhibit a wide variety of symptoms with variations in severity. As a review, these symptoms may include any, several or all of the following: increased susceptibility to bone fracture, hearing loss, spinal deformities, blue sclera, shortened stature, bowed arms and legs, ligamentous laxity and dentinogenesis imperfecta. The severity of symptoms will depend on what type of osteogenesis imperfecta the patient is diagnosed with. [15] |
Image credit: Jorde et al. [12]
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X-ray images illustrating lower-extremity bowing in a 7-year-old female patient. Image credit: Radiographics [16]
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Experimental approachA broad objective of OI research is to elucidate the molecular mechanisms involved in human bone development as they relate to COL1A1. However, I want to focus on the following experimental questions:
Model organismUsing phylogenetic analysis, mice (Mus musculus) and zebrafish (Danio rerio) were chosen as two of my top candidates to perform OI research [2,3]. To review the phylogenetic analysis, please click here. Ultimately, I selected Danio rerio due to several clear advantages. This model organism is not as costly or time-intensive due to a shorter generation time in which many embryos can be produced. Additionally, mutagenesis is highly reliable and the embryos produced are transparent, which allows for easier visual screening. This property is especially valuable in bone research in particular because it reduces the need for expensive and time-consuming x-ray technology. |
Zebrafish COL1a1 proteinUsing BLAST, I determined that zebrafish COL1a1 is 77.7% similar to human COL1A1; there are 20 collagen domains while only 12 are present in the human homolog. Experimental designIn order to appropriately address the two questions I presented in the "Experimental Approach" section, I have designed the following experimental set-up. I propose the genetic engineering of several col1a1 mutants whose tail and bone phenotypes would be observed and scored. Following this, I suggest microarray experiments be performed to observe how protein expression levels are affected within the mutant fish as compared to wild-type. This would allow further investigation into how col1a1 may be interacting within its protein network. |
Above is an image of a wild type zebra fish (F) and a heterozygous chihuahua mutant. The chihuahua mutant displays defective bone growth that can be likened to OI and was discovered in 2003. It was later determined that this mutant has a mutation in col1a1. [10] Image credit: Fisher et al.
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