Anecdotal , Historical and Critical Commentaries on Genetics The Joys of Truly Joint Research , With the Great Translocation Hunt

Within-laboratory collaborative projects wherein each worker performs the technique he or she does best are common nowadays. Opportunities for projects wherein everyone does everything are less common, but these projects bring their own satisfactions; the Great Translocation Hunt is presented as an example. LARGE laboratories with graduate students and postdoctoral fellows working on interwoven projects is the norm nowadays, but it was not always so; through most of the history of genetics, one could expect to train no more than, say, five youngsters throughout one’s entire career. (There were of course exceptions– Morgan’s original Fly Room, for example.) Of course, by or before the end of our training, we are supposed to have developed into independent scientists, capable not only of performing our procedures reliably but also of planning and interpreting them ourselves. But we still need someone to talk to; and, although of course good conversations can occur between levels, the best ones are between peers. To pick one example, only between peers can one gripe freely. Griping up risks being taken seriously and labeled a complainer; griping down should not be done. One reason why not is that griping is often about other people. Gripes about people can be let off to lay people or peers in different scientific areas, but scientific gripes require a peer with sufficient understanding of the problem to be sympathetic but not concerned. Another example is constructive criticism of one’s ideas, hypotheses, and interpretations; here, it’s fine to ask up, but what if there is no ‘‘up’’? A peer is the best one can do, and the more senior one gets, the harder it is to obtain helpful criticism. Working in an interwoven project has its pros and cons. Yes, there are peers to talk the trivia over with, but getting a group all of whom pull their own weight is rare; this inequality creates a tension I prefer to avoid, and this is one reason why I normally work alone on my projects. The exceptions, however, are projects where there is a single line of experimentation that needs more than two hands to handle the load; everyone is doing the same thing at any point, and inequalities are less of a problem (as long as n is greater than 2). When this works, there is no (scientific) joy greater. I have been privileged to share in four such projects during my career. The first and third were with Bruce Baker [the meiotic mutant hunt (Baker and Carpenter 1972) and the mitotic defects of those meiotic mutants (Baker et al. 1978)], the fourth was with Fotos Kafatos (eventually published as Barrio et al. 1999), getting the mutations for what would eventually be named salr (spalt related) as well as spalt, and the second, the Great Translocation Hunt led by Dan L. Lindsley and Larry Sandler (Lindsley et al. 1972), which involved the massed might of both the Sandler and Lindsley laboratories, is the subject of this article. Background: Dan Lindsley and Larry Sandler met in Ed Novitski’s lab, Dan as a postdoc and Larry as a graduate student. Apparently they immediately began doing joint projects (the various compound X papers); certainly they worked well together and enjoyed doing so, because later they went on sabbaticals together whenever they could. In fact, Larry had just returned from one such (with Nicoletti and Trippa as well as Dan in Rome, isolating recessive autosomal meiotic mutations from wild-caught flies, Sandler et al. 1968) when I joined Bruce for what we laughingly thought was a summer’s side project in 1969—inducing X-linked meiotic mutants with the then brand-new chemical mutagen EMS (Baker and Carpenter 1972). Bruce already had a thesis project (pal, paternal loss, Baker 1975) when we started this highly successful project, but when it Author e-mail: [email protected] Genetics 182: 929–934 (August 2009) came time to write his thesis the pal project still had a few large experiments outstanding so he defended the mutant hunt instead, and a year later I defended the analysis of the unique female meiotic mutant nod (no distributive disjunction). The rest of the female meiotics were recombination defective and interesting in their own right, but the existence of nod settled a controversy: if one can get a mutant defective in distributive disjunction, then the distributive system (a system for getting correct meiosis I segregation even when chiasmata are absent) does exist (Carpenter 1973). But the Rome experience had not satisfied Dan and Larry’s need for joint science; and, after all, waiting seven years to get together with your most important colleague is rather a long time. Dan had realized that, if enough translocations could be induced and mapped, deficiencies and the reciprocal duplications of various sizes could be synthesized at will by meiotic segregation whether or not they were viable—and that viability information would be interesting. It had long been known that small (a salivary chromosome number division or so) deficiencies could be recovered relatively easily though large ones were not recovered; either the genome is peppered with genes that must be present in two doses for viability, so any large deficiency will take out at least one such gene, or else all or most genes have small effects on viability when present in only one dose, cumulatively, so that the larger the deficiency, the lower its viability. With enough translocations one could march along a chromosome arm making deficiencies and duplications that were absolutely adjacent, guaranteed to identify all genes whose dosage mattered to the phenotype of the fly (a number of such genes were already known), and, just possibly, build a resource useful to the fly community in general. But to get that many translocations needed many hands, so the plan of joining laboratories was born: first the La Jolla group came up to Seattle for the summer of 1970 and we all induced and scored for translocations, then we separated and both groups did translocation cytology during the autumn, then the Seattle group went down to La Jolla for 4 weeks over Christmas to score the crosses generating the deficiencies and duplications, followed by data analysis and writing. But first, a digression on how this setup works. How the translocations were used: Take three Y-autosome translocations (Figure 1) with autosomal breakpoints A, B, and C that are near each other; cross them as heterozygotes in all combinations. Translocation heterozygotes give many kinds of gametes, and there were enough markers in the crosses so that all types of segregation were scorable, but the important progeny are shown in Figure 1: the autosomal deficiency between the breakpoints of A and B and its exact duplication, the exactly adjacent deficiency between B and C and its exact duplication, and the sum deficiency and its exact duplication between A and C. Not shown are the euploid sibs against which the viability of the aneuploids is measured. These aneuploids are also duplicated or deficient for Y chromosome material, but Y-material aneuploidy has negligible effect on viability so can be ignored. There is one small caveat about the sum deficiencies: they may be slightly smaller than just adding the effects of the two component deficiencies, because the middle (B) breakpoint may be slightly larger than a point—in particular, the juxtaposition of Y heterochromatin and autosomal euchromatin will usually give some inactivation of the euchromatin from position-effect variegation. Fortunately, this did not complicate analyzing the results. This distinguishes between the above two alternatives: if larger deficiencies die because they delete a gene required in two doses, then every lethal sum deficiency will have one or both component deficiencies lethal too, whereas if cumulative effects of many genes cause the sum deficiency lethality, then cases where the sum deficiency is lethal but both component deficiencies are viable should exist. How the translocations were made: So the La Jolla group drove to Seattle for the summer, bringing a newlypurchased Zeiss Ultraphot light microscope; the stocks needed to induce and balance Y-autosome translocations had been mailed ahead for expansion. But the stock building had been a bit last minute—probably the whole idea had been a bit last minute—and Dan just barely had various versions of the necessary stocks built; he had not had time to see which were the healthiest. Sets of these stocks were handed out to us grad students; I received the second-chromosome stocks to baby and expand. However, although I had been handling flies for a year by then, all that work had been on the X; the second chromosome and its balancers were new to me. And, in 1970, there was no easy way to look anything up! The book by Bridges and Brehme (1944) was unobtainable and out of date anyway, Lindsley and Grell (1968) was not available yet (at least in the Sandler laboratory, though I bought my own copy soon after), and of course FlyBase was not yet remotely conceived of. The only way to find things out was to ask someone more experienced—and I did not think I needed to. After all, all the stocks were Curly (Cy), I could see the curved wings, and I must have thought that 2L12R Cy, SM1 Cy, and CyO were just three different attempts to make the same stock rather than the reality, three different secondchromosome balancers so that the one that made the best stock could be chosen for use. CyO was the best available second-chromosome balancer at the time but it also has the lowest fertility, SM1 is intermediate, and 2L12R Cy is the most fertile but the poorest balancer. Since I thought those three bottles were different isolates of the same stock, and since none of them were going particularly well, I merged them, and I did succeed in expanding the result as a healthy stock. I was quite proud of my accomplishment until Dan asked 930 A. T. C. Carpenter