A note on RFLP probes: their dissemination and utilization

--J. L. Bennetzen

In our laboratory, we have made extensive use of the maize restriction fragment length polymorphism (RFLP) probes isolated and mapped by the Burr laboratory at Brookhaven, the Helentjaris laboratory at Native Plants (Inc.), and the Hoisington laboratory at the University of Missouri, Columbia. We have obtained most of these cloned probes directly from Dr. Hoisington, who has generously volunteered to operate a clearinghouse for these materials. Due to the numerous and continuing requests for these probes from a variety of sources and the large size of the RFLP library so far assembled, Dr. Hoisington's laboratory can take quite a while to send out the material and must forward it with only a minimum amount of descriptive information. This has led to a number of problems. For instance, most of the RFLP probes hybridize to two or more fragments on gel blot hybridization analysis, regardless of the restriction enzymes employed. This is presumably due, in part, to the predicted polyploid origin of the maize genome and, in part, to the routine presence of multicopy gene families in eukaryotes. In general, only one of these two or more bands is associated with a polymorphism in the mapping inbreds employed by Dr. Hoisington. This RFLP is then mapped and the clone designated as a marker for a specific chromosomal segment. However, anyone receiving this probe and employing it in a linkage analysis may actually be following a polymorphism for one of the unmapped bands.

Dr. Hoisington has all of the information in his notebooks regarding the number of bands any probe hybridizes to, their approximate size with specific restriction enzymes, and the identity of the polymorphic band mapped. Anyone wishing to make use of this information is allowed free access to all these notebooks upon visiting Dr. Hoisington's lab, but the material is too voluminous to send out along with each of several hundred RFLP probes. Moreover, Dr. Hoisington has not had the personnel available even to fully assemble this information in an easily digested form.

I would like to propose that a handling fee be required to obtain RFLP probes along with all of the pertinent information allowing the material's optimal utilization. This information would include probe source, probe size, probe cloning enzymes, and a digitized reproduction of the hybridization patterns observed for the probe with the inbreds and restriction enzymes employed by Dr. Hoisington in his mapping studies. Dr. Hoisington has both the data and the technology to provide this information but lacks the delegated personnel. A handling fee of $20 per clone (prepaid) would allow the hiring of a full-time technical assistant dedicated exclusively to the assembly and provision of RFLP clones and accompanying information. Compared to the current process, delivery of materials would be accelerated and their utility greatly enhanced. As a secondary but perhaps significant outcome, a handling fee would discourage requests by "collectors" with little or no immediate need for the probes. Finally, this fee would relieve Dr. Hoisington's lab of the burden of materials expense, postage costs, and personnel commitment that they have, to date, generously provided to the maize genetics community. The $20 handling charge would, of course, be waived in case of need. This fee level is half the amount charged by the American Type Culture Collection (ATCC) for microbial stocks.

For the long term, it would be most desirable to obtain commitment for the support of a maize RFLP supply house from federal or charitable sources. However, since such support is neither clearly available nor on the near horizon, I feel that charging an RFLP probe handling fee would be a valuable interim (preferably) or final solution to the current problems associated with the broad dissemination and efficient utilization of maize RFLP probes.

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

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