the Female Body GOVERNING

284
ingrid holme
is debatable. Prestigious science journals, such as Nature, portray
X-inactivation using metaphors, such as shutting up the X or A gene
that gags the X chromosome keeps females alive that lend support to
the binary sex model (Clarke, 2001). The popular and scientifi c media
coverage of X chromosome inactivation has a penchant to use verbs and
nouns associated with sound, such as “shutting up,” “a molecular gagging
order,” “muffl es,” and “silence,” to describe the research, expanding the
metaphor of DNA as information to the area of oral communication.
Verbs, such as silencing and gagging indicate a situation where genes are
either “silenced” or “vocal” and either “passive” or “active.”
However, these metaphors do not do proper justice to the active
processes involved in the inactivation of the second X chromosome.
Researchers now recognize the second X chromosome is inactivated into
a Barr body at the 64-cell stage of the human female fetus. Evidence
from studies of mice has shown that the fi rst step of X chromosome
inactivation is the methylation (i.e., tip-ex) of most of its genes, through
the production of RNA from the Xist gene. The second step is the modifi
cation of the histones, which causes the X chromosome to condense.
Within one to two cell cycles most of the genes on the X chromosome
seem silenced. The newfound importance given to chromosomal RNA
in this mechanism is typical of the change from genetics to genomics.
Genes can no longer be viewed as complete and self-standing DNA
sequences or the fi rst step of the linear dogma that understands DNA
to code for RNA, which codes for proteins. Instead, DNA is increasingly
analyzed within an interactive structural cellular network, in which
factors such as chromosomal RNAs play an important part. Metaphors
with connotations of abrupt events such as “gagging” do not do justice
to this interactive and processional nature of inactivation.
Furthermore, current research has revealed that the X chromosome
is not simply “gagged” but that 19% or one-fi fth of the second X chromosome
is active (Graves, 2000). Those remaining active genes could
result in double dosage of gene products, thus, the genetic difference
created by the inactivation of the X chromosome should not only be seen
as one of different gene products, but as one of different levels of gene
product. Currently these genes are called “escapees,” which brings into
mind improper and unnecessary entities. However, the importance of
these active genes is illustrated by Turner’s syndrome. This is a condition
where a person has only one X chromosome—no second X chromosome
or Y chromosome (X-O). These people are generally women of short
stature, who lack some factors connected with reproduction and who
may have poor spatial ability attributed to the nondominant (usually
the right) hemisphere (e.g., Netley & Rovet, 1982). Turner’s syndrome