| Parichy Lab |
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| Overview | |
nutria mutants are dwarfed by their wild-type siblings. We are seeking the molecular and cellular bases for these defects in growth and proportions.
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| 1. nutria corresponds to trpm7 | |
We cloned the nutria mutant in collaboration with the Cornell and Henion labs. We identified the affected gene as trpm7, encoding a dual function cation channel and kinase.
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| 2. trpm7 functions in kidney | ||||
In situ hybridization reveals trpm7 expression in kidney as well as the corpuscles of stannius that regulate calcium levels... |
...and trpm7 mutants develop kidney stones, shown below with green fluorescence. | |||
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| 3. Skeletal patterning requires trpm7 | |
Skeletal development is severely perturbed in trpm7 mutants. Larvae are stained for bone and cartilage.
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| 4. Ossification timing requires trpm7 as well | ||
In zebrafish and other vertebrates, bones are either endochondral, developing through a cartilage intermediate, or intramembraneous, developing without a cartilage intermediate. In trpm7 mutants, clearing and staining reveals that endochondral ossification is accelerated (red labels) whereas intramembraneous ossification is delayed (green labels).
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| 5. Quantitative analyses demonstrate different effects of trpm7 mutation on different types of bone | |
| The difference between bone types is especially clear when we quantify ossification timing for many different bones. Shown below are ossification sequences for 87 bones in wild-type and mutant larvae. In the mutant, endochondral bones (red connectors) ossify earlier whereas intramembraneous bones (green connectors) ossify later, as compared to wild-type. Color coding of individual bones corresponds to where they are located in the fish. | |
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| 5. Current studies |
| We are now working to identify when trpm7 is required, how trpm7-dependent cation homeostasis and kidney function affects bone development, and which molecular pathways are involved. |
