Antagonistic Regulation

Hematopoetic stem cells are pluripotent, that is, a single type of cell can commit to a variety of fates. In the bone marrow, hematopoetic stem cells differentiate into cell lineages that comprise our blood. Lymphocytes, polymorphonuclear leukocytes, platelets and erythrocytes all descend from the same type of cell. Both synergistic and antagonistic gene expressions govern these fate determining events.

At the fork in the road where a common lymphoid progenitor, a descendant of hematopoetic stem cells, commits to either a B-cell or a T-cell lineage, the relationship between Pax 5 and Notch 1 is best described as antagonistic. Expression of Pax 5 both commits a common lymphoid progenitor to the B-cell lineage and inactivates Notch 1 signaling. Conversely, active Notch 1 signaling commits a common lymphoid progenitor to the T-cell lineage and inhibits the expression of Pax 5.

Is it a good idea to remain close friends with people you’ve dated? I thought about this today at the post office. Because tax day falls on a Sunday this year, we’ve been given a reprieve until the 17th. Extra time notwithstanding, I put off doing an old girlfriend’s taxes until the final weekend. This sunny Saturday morning I found myself standing in line with about twenty other procrastinators waiting for a post date stamp. Yeah, not only did I complete her taxes, I mailed them for her as well. Sucker, I know. In my defense, I get some free food (Honestly, is there any better kind?) and sincere appreciation. If for a brief moment we were to put consideration of food aside, feeling relevant and appreciated is probably my main motivation in life.

But is this determining motivation, especially when it relates to women I’ve dated, somehow inhibiting other fates? I got a message from a friend the other day saying that I shouldn’t get “hung up” on my recent ex; that I should move on. Funny, I thought I had. I guess, objectively one could say that I haven’t. I haven’t gone on any dates and nobody has caught my eye. But for the most part, I’ve never gone on dates. I’ve either been involved with someone or I’ve been alone. And because of that, the qualities that attracted me to them romantically still have validity even after the romance has ended. I’m fortunate to know and to have been with caring, intelligent and funny women who challenge my assumptions and motivate me towards better things. I’d be less if I did not still count them among my friends.

Don’t get me wrong, when you’ve been in love it’s not easy to back off and as Akon raps, “respect boundaries.” But, as difficult as it is, it is also a committed step in this fate determining event.

I did an out-and-back on the bike path. At mile 11, I stopped and walked it in. Right calf cramp or slight pull. When is this thing going to heal? 39˚F, sunny with winds from the NW @ 12 mph.