Gene regulation in mammals is exceedingly complex and undoubtedly involves use of transcriptional factors. mSEC has been known to be involved in controlling the proliferation of osteoblast precursors in bone. Students designed experiments to determine properties of mSEC.
In Experiment 1, purified mSEC was delivered orally to mice in varying doses once a day for four days. An assay was then used to check for osteoblast proliferation (Table I). As a negative control, solution containing no mSEC was also injected in a group of control mice.
| [mSEC] delivered | Day 1 | Day 2 | Day 3 | Day 4 |
| 10 mg/ml | 4 | 3 | 3 | 3 |
| 5 mg/ml | 3 | 4 | 3 | 2 |
| 1 mg/ml | 4 | 3 | 2 | 2 |
| 100 μg/ml | 3 | 3 | 4 | 3 |
| 10 μg/ml | 4 | 3 | 3 | 1 |
| CONTROL | 3 | 4 | 3 | 3 |
Table I
A similar experiment is conducted in a tissue culture system in which osteoblasts were grown on a Petri dish (Table II). mSEC was then added and proliferation was measured by the same assay as in Experiment I. As with Experiment I, mSEC was added daily for a total of four days.
| [mSEC] delivered | Day 1 | Day 2 | Day 3 | Day 4 |
| 10 μg/ml | 5 | 13 | 10 | 11 |
| 5 μg/ml | 4 | 11 | 10 | 10 |
| 1 μg/ml | 5 | 8 | 6 | 7 |
| 100 ng/ml | 3 | 6 | 6 | 7 |
| 10 ng/ml | 4 | 4 | 3 | 4 |
| CONTROL | 3 | 4 | 3 | 3 |
In humans, mSEC levels are most likely to be high during:
I. Fasting
II. Gestation
III. Puberty
I only |
|
III only |
|
II and III |
|
I, II and III |