Strand orientation and GC skew

Question

[A_heath]

Hi all,

I have a question regarding the meaning of GC skew. In the bilbiography, I found this:

"GC skew graph segregates the genome into two regions: one with an excess of G over C corresponding to the leading strand, and the other with an excess of C over G corresponding to the lagging strand." from this article.

Based on this, I should have a sense strand with a +GC skew and the anti-sense strand with a -GC skew.

I used CGView to create a map of an assembly, and the result is displayed below:

As you can see, the strands do not have a uniform GC Skew. Is this normal? If not, is the problem coming from the assembly itself?

The species of this genome is Mycoplasma pneumoniae.

Thank you so much for your help on this!