Question

SAR/MAR sequences were postulated to form the bases of these radial loops.  SAR/MAR sequences were defined experimentally by one approach for SARs and by a different experimental approach for MARs. This question is about our experimental foundation for thinking about models for chromosome folding and nuclear organization as discussed in class which lead to the idea of a radial loop model of chromosome origination.

i.  What approach was used for SARs?

ii.  What approach was used for MARs?

Answer 1

Small-scale studies have suggested that NaCl extracted nuclear matrix preparations will identify MARs that are associated with transcriptionally active regions. Similarly, since LIS disrupts transcription complexes, the SARs thus isolated were expected to support an indirect function, such as potentiation, to spatially poise rather than direct the interaction of the nuclear scaffold with the transcription factory. To test these relationships, the analysis of nuclear scaffold/matrix profiles relative to expressed and silent genes was undertaken.