Help asked for Sorting large diatoms

David Galbraith galbraith at
Sat Sep 1 13:17:46 EDT 2007

Hi Machteld:

I see Asterionella is about 5 microns wide by 100 microns long.  This 
will be a challenge!

I would try the 200 and 400 micron tips, noting that you will have to 
reduce the system pressure considerably as well as the piezo 
actuation frequency to obtain droplets.  You may also need to modify 
the deflection plate assembly and observation point to figure out the 
drop delay and obtain sort streams.  The general flow issues are 
described in our publication: HARKINS KR, GALBRAITH DW (1987) FACTORS 
BIOLOGICAL PARTICLES CYTOMETRY 8 (1): 60-70.  We also have a MoFLo, 
so please feel free to contact us with specific questions. Regarding 
detection and discrimination of various green algae and diatoms, 
chlorophyll autofluorescence provides a robust signal that is 
excitable at most laser wavelengths. I would employ a log signal in 
exploring this for discrimination, combined with log side and/or 
forward scatter.

Best wishes,

David Galbraith

At 12:07 AM 8/31/2007, Rijkeboer, Machteld wrote:

>Dear All,
>I have a question concerning counting and also sorting large 
>freshwater diatoms (like Asterionella formosa). We apply a MoFLo 
>with 70, 100 mhu nozzletip. We also have a 200 and 400 mhu tip, but 
>lack the experience using them.
>So I am asking you: is there someone with experience on sorting 
>large particles (>100 mhu). We want the algae to stay alive
>And how about discriminating between green algae and diatoms from 
>natural waters. (we may apply 3 lasers: 488 nm, 633 and the last one 
>can be adjusted to any colour we like)
>I am not very experienced in flow cytometry yet, so I like to 
>communicate with people about this subject.
>Machteld Rijkeboer
>Ms. Machteld Rijkeboer
>Centre for Limnology
>Rijksstraatweg 6
>3631 AC Nieuwersluis
>The Netherlands
>tel:+31 ( 0)294239334

David W. Galbraith
Professor of Plant Sciences
& Professor, Bio5 Institute
University of Arizona
Office: 341 Keating Building

Mailing address:
BIO5 Institute
The University of Arizona
1657 E. Helen St.
Tucson, AZ 85721-0240

Tel: (520) 621-9153
Fax: (520) 626-4824
Email: galbraith at  
-------------- next part --------------
HTML attachment scrubbed and removed

More information about the Cytometry mailing list