Meeting Reports 302 7th International Conference on Plant Pathogenic Bacteria:

Z. Klement, M. Hevesi, S. Sale, Zs. Rozsnyay, and J. Ndmeth 303 Regio Meeting on Plant Molecular Genetics at Freiburg:

L. Otten

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Schedule of Events Meetings Workshops

Positions Available

Author Index Vols. 1--7

Cis a n d T r a n s

ISPMB Elections

T he Board of Directors of the ISPMB has 16 elected members rep- resenting North America (6), Europe and the MidEast (7), and the Far East (3). The composition of thepresent board is shown on

the back cover. The terms of Lous van Vloten-Doting and Masahiro Sugiu ra expire at the end of 1989. Acting as a nominating committee, the Board will propose three candidates for each seat. A ballot for the election is enclosed with this issue of the Reporter.

Loose Expressions

E nglish, the principal vehicle of scientific communication for the last four decades, is a forgiving language: a misplaced comma or non- idiomatic construction may sound strange to an anglophone, but

the meaning need be no less clear. Problems in scientific communication arise not so much from dangling participles as from imprecision, a sin of which anglophones and non-anglophones are equally guilty.

Sometimes the precise meaning of terms becomes obscured by dilu- tion: a word or phrase with a specific denotation becomes a "buzz word"

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and is extended to wider and even contradictory meanings. People feeling no anxiety say they are anxious to see us; anticipate is used to mean expect; and flight attendants assure us that the airplane will take off momentarily. Such dilutions of meaning are also a phenomenon in molecular biology.

A Gene Is Not a Protein

The terms for genes and gene products are frequently used inter- changeably, sometimes without loss of meaning but at other times ca u sing serious ambiguity. In an article I was reading the other day, there was a diagram of plasmids labelled with "CAT", "GUS', and "NPTII," abbreviations for chloramphenicol transacetylase, b-glucuronidase, and neomycin phosphotransferase II, respectively. No great intellectual exertion is required for me to understand that the plasmids contain the genes for CAT, GUS, or NPTII. Further on I read that "GUS was cloned into Nicotiana tabacum and the F 1 plants were found to contain GUS." Now I am in treacherous seas: tobacco was transformed with the gene for b-glucuronidase, but what has been detected in the Fl's--b-glucuronidase or the gene for b-glucuronidase? Still further on I find "GUS" used to denote b-glucuronidase and the gene for b-glucuronidase in consecutive sentences. From the context I infer the author's meaning: the gene forb- glucuronidase was detected by Southern blots whereas the activity of b- glucuronidase was detected enzymatically. I have better usesof my time than to struggle with the author's intentions.

Microbiologists solved this problem years ago: genes and gene products not only have different names, their symbols are different in kind: the gene lacZ codes for the protein LacZ. Symbols for gene products come in different colors, but can never be confused with gene symbols first three letters, lower case; additional characters capital- ized; all italicized, no space (Demerec et al., 1966). If we plant types would only pay attention to our bacterial elders, I should be spared wrestling with the kinds of ambiguities noted above: uidA is the canoni- cal symbol for the gene coding for GUS, just as cam codes for CAT and kan codes for NPTII (Bachmann, 1983; Berg et al., 1975; Neidhard t et al., 1987).

G e n e E x p r e s s i o n

Having revealed a testy disposition, I may as well let it all hang out. Every high school student knows that genes are coded in DNA (and sometimes RNA) and that gene products are proteins (and sometimes

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RNA). Now ask the person at the next desk what is meant by gene expression? Genetic types will speak of the phenotype of the gene; molecu- lar types will say that gene expression refers to the appearance of thegene product. The question is good for five minutes of useful discussion. Whatever differences in nuance, the term gene expression has a special importance to geneticists and molecular biologists alike.

I read that "rbcS-3A is expressed in mesophyll but not in epidermis". Crystal clear. Without the concept of gene expression (and gene symbols), we should have to write, "products of a member of the family of genes coding for the small subunit of ribulose-bisphosphate carboxylase accu- mulate in the mesophyll but not in the epidermis." Well, almost crystal clear. Further information would be needed to tell us whether the expression of rbcS-3A was measured by the accumulation of its tran- scripts or of its protein product, but we'll save that for another time.

More serious consequences arise from a growing tendency to extend the term expression to mean simply the appearance of a protein. Cells are said to "express" phaseolin, coat protein, phytochrome. Can I say that my reticulocytes "express" hemoglobin? IfIgo into the sun, does my skin

continued on p. 311

Appoin tments and Awards

Andre T. Jagendorf of Cornell University (USA) received the Barnes Award andSharon Long of Stanford University (USA) received the Charles Albert Shull Awardfrom the American Society of Plant Physiologists.

Robert Symonds of the University of Adelaide (Australia) was elected Fellow of the Royal Society.

Don Weeks Director, Center for Biotechnology

and Professor of Biochemistry and Biological Science University of Nebraska, Lincoln (USA)