Jacob,
Although the use of patch-clamp pipettes and micromanipulators come to
mind, I just wonder about what would happen to the pipette and the
fluid in it when you flash-froze it. Nonetheless, the idea of a means
to transfer small crystals easily and quickly has some merit. In
another incarnation many years ago, I dabbled in developmental
biology. To select out small invertebrate eggs (from sea urchins and
sand dollars), which were about 80-100 microns in diameter, we used a
"braking pipette" to them pick them up, one at a time. Even smaller
single amoeba cells (like amoeba) can be handled in this way. While
you could attach one to a micromanipulator, I always used it by hand
as it was much faster.
There are several different types, and they could be used to handle
objects/cells as small as 20 microns in diameter. A Google book
search will bring up Methods in Cell Physiology, Volume 1 by David M.
Prescott,1964. See Chapter 8, page 128, (G. E. Stone and I. L.
Cameron) for a description of one style of braking pipette. The
primary concept is that a narrow constriction/aperture within the
pipette causes enough air flow resistance to increase markedly the
amount of suction needed to move a small volume of liquid. Hence, we
could "mouth pipette" single cells trivially without sucking them
clear through the pipette or taking in too much fluid. For those who
have done "wet" mounts of crystals in capillaries, we know how
difficult it can be to control the suction.
We made our braking pipettes out of two pieces: (1) a sampling
capillary with one end pulled the make the narrow aperture and (2) a
holder made out of a cut-off Pasteur pipette. The sampling capillary
was placed inside the cut-off Pasteur pipette so the sampling tip
stuck out. Then the junction was sealed with the old main-stay:
sealing wax. Attaching a tube to the other end of the Pasteur pipette
allowed for mouth pipetting. It's about a 10 min job to prepare.
Cheers,
Michael
Also see: Lloyd Claff, C. ''Braking'' Pipettes Science, Volume 105,
Issue 2717, pp. 103-104
****************************************************************
R. Michael Garavito, Ph.D.
Professor of Biochemistry & Molecular Biology
513 Biochemistry Bldg.
Michigan State University
East Lansing, MI 48824-1319
Office: (517) 355-9724 Lab: (517) 353-9125
FAX: (517) 353-9334 Email: garav...@msu.edu
****************************************************************
On Mar 27, 2009, at 12:34 PM, Jacob Keller wrote:
I think Dr. Loll has expressed my reasons for my original
suggestion. When there are skins, evaporation, etc., "crystal
catching" can be a real pain, and then you break your best crystal...
What if you could just go up to your intended crystal and vacuum it
up, and whisk it away to the dewar?
Jacob
----- Original Message -----
From: Patrick Loll
To: CCP4BB@JISCMAIL.AC.UK
Sent: Friday, March 27, 2009 8:35 AM
Subject: [ccp4bb] Fwd: [ccp4bb] Crystal vacuum cleaner
Pretty cool, but the examples shown are all gigantic. Having just
spent a frustrating several hours chasing 5 um crystals, I'd give
half my kingdom for a simple way to catch THOSE little buggers (damn
you, surface tension!).
Begin forwarded message:
From: Patrick Shaw Stewart <patr...@douglas.co.uk>
Date: March 27, 2009 8:41:53 AM EDT
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] Crystal vacuum cleaner
Reply-To: Patrick Shaw Stewart <patr...@douglas.co.uk>
Jacob
Have you seen the Crystal Catcher system, developed in Japan?
http://adsabs.harvard.edu/abs/2008APExp...1c7002K
Some of us saw it at a recent IUCr meeting, but I don’t know anyone
who has tried it with their own proteins
Patrick
---------------------------------------------------------------------------------------
Patrick J. Loll, Ph. D.
Professor of Biochemistry & Molecular Biology
Director, Biochemistry Graduate Program
Drexel University College of Medicine
Room 10-102 New College Building
245 N. 15th St., Mailstop 497
Philadelphia, PA 19102-1192 USA
(215) 762-7706
pat.l...@drexelmed.edu
