Well, Ellen, the opinion of us in Agilent is that if you're wanting to make a
judgement of the
diffraction qualities (resolution limit, mosaicity and unit cell, etc.) of
(putative) protein crystals,
in situ, then don't bother with visible light at all: instead use X-rays !!
For this reason, we've
developed the PX Scanner system. With the development of ever brighter
microfocus sources,
increasingly sensitive / extremely low noise CCD area detectors and the
availability of 'X-ray friendly'
crystallisation plates, the capability of the PX Scanner for high throughput
crystal screening work
has never been higher.
All are Welcome.
Best Regards,
Marcus Winter (Agilent Technologies)
http://www.chem.agilent.com/en-US/products-services/Instruments-Systems/X-Ray-Crystallography/PX-Scanner/Pages/default.aspx
-----Original Message-----
From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Ellen
Gualtieri
Sent: Thursday, February 20, 2014 5:14 PM
To: [email protected]
Subject: Re: [ccp4bb] identifying protein crystals via visible light only?
Hi Richard and All,
At Formulatrix we haven't yet seen an algorithm that can come even close to
what the human brain can do for drop scoring. Crystals come in too many shapes,
sizes, plates, and confusing backgrounds making automated detection
extraordinarily difficult. Because of this, we have found users will not trust
or use an automated scoring algorithm for visible light. Plus, these algorithms
usually only reliably pick out the easy crystals which a human can usually do
in a flash by just looking at 96 thumbnails. If there is a an algorithm out
there that is successful with visible light crystal detection, we would love to
hear about it.
Indeed, as Jose and Zhijie points out, when you factor in additional detection
technologies like UV and SHG (Second Harmonic Generation a.k.a. SONICC) then
image processing can start to be helpful. In this case, however, Formulatrix
only uses image processing to resort the images to put drops most likely to
contain crystals at the top of the list. We call this auto scoring but it's
really auto sorting. We never pitch this as infallibly able to score drops,
because it certainly isn’t.
Interestingly, the additional information from UV or SHG combined with auto
scoring doesn't necessarily reduce the time looking at drops. Yes, you can find
the easy crystals much faster with these techniques. But, what we see instead
is we are giving users even more information to look through and the advantage
isn’t a time savings for looking at drops. Instead, you find smaller crystals
and find crystals you otherwise would have missed. This gives you more hits
that you can optimize sooner.
We would love to hear further opinions, especially contrarian, from the
community on this topic.
