Question

Some species of finches have more robust beaks in order to crush seeds available in their environment. Recent data show that their BMP4 expression in the developing beak is initiated sooner than other species, resulting in more tissue growth during embryogenesis.

First, indicate whether this is an example of heterotopy, heterochrony, heterometry, or heterotypy, defining your chosen term (3 pts). Second, describe how you might use the chicken embryo as a model system to test the hypothesis that this earlier timing of BMP4 expression is responsible for more robust beaks in some species of finches. Be sure to provide a brief description of the relevant technique(s), and to include at least one control (6 pts).

Answer 1

1. Heterometry: it is the phenomenon which d describes, happening of developmental changes based on the amount of expression of particular genes and the proteins produced by those genes. Heterometry is seen in different species of Galapagos finches.

2. Analysis in chicken embryo model

Cloning of BMP4 gene

BMP4 gene should be amplified , carried in to suitable viral vector and transferred to E coli cell and cultured. The correct E coli colony should be selected using the proper antibiotic. Finally the BMP4 gene copies should be isolated from the E coli.

Transfection of BMP4 gene to chicken embryo

Include two groups of chicken embryo three each, control group and test group. To test group embryos transfect the cloned BMP4 gene. Transfection can be done by liposomal or electroporation method.To the control group embryos administer the transfection buffer.

Now check the time and length of beak development in both the group of embryos. If in the test group beak has started developing earlier we can conclude that BMP4 gene could induce early development of beak.