| Summary: | 碩士 === 慈濟大學 === 分子生物暨人類遺傳學系碩士班 === 100 === The placement of many visceral organs is left-right (L/R) asymmetry in
vertebrates. For example, heart and liver are in the left site and pancreas is in the right
site. In zebrafish, laterality establishment requires laterality organ, identified as
Kupffer’s vesicle (KV). The lumen of the KV forms from a group of noninvoluting
Dorsal Forerunner Cells (DFC). The notch signaling has been shown to affect L/R
asymmetry in mice. It is been also reported that, in deltaD zebrafish mutant, gut
laterality was abnormal, but the heart jogging was not affected. We used mind bomb
(mib) mutant fish for inhibiting notch signal pathway and found abnormal patterning
of visceral organs including the gut laterality and heart looping. Some expression of a
laterality gene, spaw, became bilateral. The expression of lefty1, a molecular barrier at
midline, was disrupted. Furthermore, cilia length in KV were shorter in the mib
mutants. In addition, we also used morpholino (MO) to knockdown deltaA ligand. In
the morphants, abnormal L/R asymmetry of the gut and heart was also observed.
Expression pattern of spaw was changed. The midline structure, indicated by the
expression of no tail (ntl), was affected. However, different from mib mutants, cilia
length of the morphants was normal but the number was reduced. We also found the
area of KV was reduced significantly in the morphants. Notably, we did find the DFC
morphology was disorganized in the morphants at 90% epiboly stage. In summary,
notch signaling may control L/R axis determination in different steps.
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