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(6)
Mechanism 6
is definedbythe
α
values ranging from 183
◦
to 267
◦
and
indicates that both
TL
and
TR
decreases;
(7)
Mechanism 7
is definedbythe
α
values ranging from 267
◦
to 273
◦
and
indicates that
TL
does not change although
TR
decreases; and
(8)
Mechanism 8
is definedbythe
α
values ranging from 273
◦
to 357
◦
and
indicates that
TL
increases even though
TR
decreases.
Note that
Mechanisms 9
is not shown above because it is defined not by
α
but by
the values of ∆
TL
and ∆
TR
both being zero.
Since there are 5 vectors per
TL-TR
trajectory, there are a total of 5
5
,
725 =
28
,
625 values of
α
to be calculated. These values are calculated using the formula
given in the previous section and displayed in Table 12.1. The rows numbered 1
through 5 refer to the 5 time intervals and the columns numbered 1 through 8 refer
to the mechanisms of controlling mRNA levels. Due to a large number of genes
involved, we used the normal approximation approach, leading to the results that
the observed proportions for Mechanisms 1, 2, 3, 4, 6, 7, and 8 are significantly
different from the expected except for Mechanism 5. In other words, all of the 8
mechanisms are observed to occur in budding yeast cells under the experimental
conditions employed, except Mechanisms 5 and 9.
×
Table 12.1. The frequency distributions of the 8 modules of RNA metabolism (defined in the leg-
end to Fig. 12.2) as the functions of the 5 time periods following the glucose-galactose shift.If the
angles are randomly distributed over 360
◦
, the expected distributions can be calculated as shown
in the 8
th
row. The
p
-values for the difference between the observed and the expected distri-
butions are given in the last row.
The differences are all significant, except for Mechanism 5.
The numbers in Table 12.1 represent the frequencies of the different mech-
anisms that occur in budding yeast during one of the five time intervals. Thus,
during the first time interval (
i.e.
, from 0 to 5 minutes), no gene experienced (or ex-
hibited) Mechanism 1; 142 genes experienced Mechanism 2; 234 genes exhibited
Mechanism 3; 3,470 genes experienced Mechanism 4; 96 experienced Mecha-
nism 5; 1,732 genes experienced Mechanism 6; 12 genes experienced Mechanism
7; and 39 experienced Mechanism 8. If the various mechanisms occur randomly
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