On Thu, 18 Mar 1999, Michael J. Lyon, Ph.D. wrote:

> Molecular Probes has introduced a new fluorchrome, Alexa.  Has anyone used any of the different conjugates or the new Alexa 488 signal amplification kit for fluorescein conjugate probes?  What were your results?  MP says they are much more photostable. Any comments welcome.
> 
  The Molecular Probes literature does not give any indication
  of what Alexa is - just says how good it is for everything.
  The use of a secret substance in research cannot be justified
  (what decent journal would publish your results?). With all
  the fuss about reagents for diagnostic use it is also difficult
  to imagine anyone daring to use a completely unknown labelling
  reagent in a clinical lab. One is left wondering who Molecular
  Probes expects the customers to be! Their catalogue is full of
  structural formulas and other information about their other
  fluorochromes. Why keep this one secret? Until they give some
  simple information about their Alexa label, they cannot seriously
  expect anyone to buy it. After all, there is no shortage of
  fluorescent labelling compounds whose chemistry is fully disclosed
  and discussed in textbooks and peer-reviewed journals.

 John A. Kiernan,
 Department of Anatomy & Cell Biology,
 The University of Western Ontario,
 LONDON,  Canada  N6A 5C1