The Rate-Limiting Step

Must. Go. Faster.
Must. Go. Faster.

That's the basic mantra I repeat to myself as I perch next to the microscope, rapidly scanning root systems, typing data into the computer, and plunging root samples into chemical buffers.

There's a basic principle in biochemistry which says, essentially, that a reaction can only go as fast as its slowest step.

It follows the same idea as the old phrase, "A chain is only as strong as its weakest link." Or, in Bay Area lingo, you'll only get to SF from the East Bay as fast as traffic on the Bay Bridge will let you, no matter how clear highways like the 580, 680, and all the other 80's are. The rate at which cars can squeeze through the narrow trans-bay span becomes the rate-limiting step to transportation.

These days, I'm the rate-limiting step.

As always here at Landcare, I've had terrific help with my harvest. The seedlings must be carted in from the glasshouse, measured, and washed clean of dirt before I can inspect their root systems under the microscope. (We're also taking soil samples in case we want to do some further genetic and biochemical analysis.) K. works as efficiently as always, preparing the seedlings two-at-a-time and stashing them in water-filled plastic cups to await my attentions.

It takes about fifteen minutes for me to process a seedling, so I'm expecting to spend about 100 hours on the microscope while here at Landcare. Together with the time required to extract DNA (and make backup copies of the samples I'll be carting back stateside in case of issues with United States border security), I'm expecting to be rather tight on time on this trip.

As of end-of-day on Saturday, I'm through 152 of ~500 seedlings, optimistically on track to make my Tuesday flight. I've tallied 55,176 root tips, and taken 1,374 DNA samples.

Still, I haven't looked in the greenhouse at those ominous rows of Douglas-fir seedlings awaiting their turn to face the wash-and-clip treatment. When I think of heading out there tomorrow to survey progress and collect more samples, I can't help but remember a recent conversation with K.:

"So does it look like we're making any progress," I ask K. as she returns from the greenhouse with the latest tray of seedlings.

She pauses for a moment. "Err.... No."

I sigh, then grab the latest batch of washed seedlings and head back to the microscope.