Question

One of the big surprises to come out of comparative genomic studies of certevrages has been the finding of Ultra-conserved noncoding elements. Describe 2 hypotheses that could account for these and briefly describe how you would test the hypotheses.

thank you!

Answer 1

Answer:

The extremely conserved DNA segments showing hundred percent similarity over 200 base pairs is ultra concerved segment. In human genome over 481 such sequences are seen. Of that over half are not transcribed.

Several hypothesis have been put forward for ultraconserved non coding elements.

a) strong negative selection pressure hypothesis

Vital gene regulatory information lies within this segments.

b) reduced mutation rate hypothesis

This suggest, these sequences are in hyper repaired form or hypomutable state.

The first hypothesis can be tested by the gene sequence of segmental duplication and copy number variants. Here the extra segments or copy number variants wont hold ultra concerved non coding regions and there for, they are of reduced fitness.

Also we can test by removing some such ultra conserved segments in experimental animals. And look for functional role of these regions invivo.

The second hypothesis can be tested by inducing mutation in ultraconserved non coding region. Then prevent any repair process by inhibiting DNA repair enzymes. This can be done in experimental animal and tested invivo. In case if hypothesis is true, animal will show decreased survival or defective offspring or no offspring.