今年诺贝尔奖得主Jack Szostak回忆导师吴瑞的文章

　　

　　Jack Szostak从1974年到1979年，随吴瑞做的研究生，并留在吴瑞实验室做了博士后。

　　1979年，27岁的Szostak到哈佛大学医学院附属癌症研究所任助理教授、独立领导实验室。1980年，他在会上听过Elizabeth Blackburn报告后，与她合作。他当时正在奇怪为什么不能在酵母细胞稳定地转染和维持线性DNA。当他将Blackburn在四膜虫中发现的CCCCAA序列接到DNA末端后，成功地稳定转染了酵母。这篇1982发表于Cell杂志的文章，为2009年诺贝尔奖委员会引述。

　　这篇文章一个意义是说明末端序列的重要性，而且在不同生物有保守性。另外，对于Szostak 的研究初衷来说，是可以解决一个技术问题，这个发现成为制造酵母人工染色体（yeast artificial chromosome）的一个重要步骤，这不仅对于研究酵母的科学家有用，其后还为包括人类在内的基因组研究起了作用。Szostak的科学贡献不仅限于此，有些科学家可以认为他的其他研究贡献大于此。

　　Szostak在癌症研究所任职几年后，他长期在麻省总医院（MGH）的分子生物学系工作。这个因为 公开推广乙醚做麻醉剂而开创现代外科新时代的医院不仅支持应用研究，也长期支持对生命科学的基础研究。

　　Szostak的科学训练，主要在吴瑞实验室进行。2008年吴瑞教授去世后，他曾撰文悼念。

 

　　Szostak JW, Blackburn EH. Cloning yeast telomeres on linear plasmid vectors. Cell 1982; 29:245-255.

 

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Ray Wu, as remembered by a former student

Jack Szostak

　　Some 35 years ago, I had the good fortune to be accepted into Ray Wu’s lab as a graduate student. Ray was already well known for his pioneering studies in DNA sequencing, and his lab was quietly humming with the excitement of the new approaches being developed for DNA labeling, sequencing and synthesis. Looking back, I am somewhat surprised that Ray accepted me into his lab-I was not a chemistry or biochemistry student, and I was transferring from another Department where I had become disillusioned with the prospects for completing a thesis project (of my own naïve design). I’d like to briefly recount the story of how I came to work for Ray, as I think it sheds some light on his personality, in particular the importance that he placed on the support and teaching of young, inexperienced students. If he saw potential in someone, he would do whatever it took to provide the opportunities and resources for that person to develop as a scientist.

John Stiles, a fellow graduate student, and I had come up with what was, in 1973, a technically challenging but novel approach to the detection of a specific mRNA. The idea was based on the recent completion of a short stretch of the DNA sequence of the yeast iso-cytochrome c gene, which had been determined by the remarkable strategy of sequencing the protein products of a series of frameshift mutants (in Fred Sherman’s lab, in nearby Rochester, N.Y.). We felt that it should be possible to chemically synthesize a DNA probe that would allow us to detect the gene and its mRNA by hybridization. But how could we actually do this?

The genetic tools for the project were available in Fred Sherman’s lab, but the chemical synthesis of DNA oligonucleotides was still a significant undertaking back then. Looking around at the Cornell faculty of the time, it seemed to us that Prof. Wu’s laboratory was the best and probably the only place that this project could be carried out. But would the famous Prof. Wu listen to a couple of unknown graduate students pushing a wild plan? It was with some trepidation that John and I went to see Prof. Wu, and nervously tried to explain the idea we had come up with. Fortunately, Ray was indeed intrigued by the idea. Although our proposal must have seemed somewhat obvious to him, Ray smiled and nodded and said that it sounded “very interesting” (only later would I learn what high praise this was coming from Ray Wu!). Eventually, Ray agreed to help us carry out our plan, and to arrange the necessary collaboration with Fred Sherman.

It took a bit more time to persuade Ray to accept me as a transfer student so that I could do the synthetic part of the project in his lab. Transferring students between departments was not common practice, and Ray was reluctant to cause offence by seeming to poach another Professor’s student. My total lack of experience in the necessary chemistry may also have made him hesitate. I never knew exactly what negotiations took place behind-the-scenes, but eventually the bureaucratic barriers seemed to melt away, and perhaps worn down by my persistence Ray decided to give me a chance. Thus on a typically cold, snowy Ithaca day on January, 1974, I found myself in Ray’s lab, faced with the challenge of learning enough basic organic chemistry to chemically synthesize the 15-mer oligonucleotide that we needed.

To put that adventure into context, and to give a bit of the flavor of working in Ray’s lab at the time, it may be worth mentioning some of the lab activities that were needed to reach our goals. The enzymes needed to manipulate DNA, such as the polynucleotide kinase used for end-labeling were not commercially available and were purified by the members of Ray’s lab. Later, when restriction enzymes were discovered, we all took turns purifying the enzymes we most wanted. Even simple reagents such as γ-32P-ATP could not be purchased but had to be made in the lab. We had a special little isolated room in the basement of Wing Hall where we handled larger quantities of radioactivity. Once a month, we received 100 mCi of 32P-phosphate, and one of our less pleasant lab jobs, done by all in rotation, was to use this to enzymatically generate the γ-32P-ATP we all needed to label DNA and RNA fragments. Sequencing bits of RNA required a special high voltage apparatus for paper electrophoresis, with the constant danger of fire should the paper dry out, not to mention the possible electrocution of careless students. The synthesis lab was in a separate room due to the fishy smell of pyridine. The facility was small, and as I recall our most advanced analytical method was thin-layer chromatography, but it allowed us to make a few oligonucleotides. Of course what made everything work, and what made Ray’s lab such a great place to be, was that he had marshaled the entire array of resources required to participate in the emerging field of molecular biology. Whenever important new methods were developed elsewhere, Ray seemed to know the people involved, and made sure the methods were imported to his lab. The first cloning vectors, the first restriction enzymes, the latest sequencing methods - Ray made sure we had all of these. I always felt that Ray had provided us with an environment where we could do anything, limited only by our imagination and ability, and never by physical resources.

Ray’s unobtrusive day-to-day management style complemented this general atmosphere of scientific freedom. There was no micro-management, and he generally allowed people to explore their own ideas. Because he was never harshly critical, people felt free to be creative and try out their own ideas. Of course, Ray was always pleased to hear of some new advance emerging from within the lab, and he was always there in case advice was needed.

To get me started on my project, Ray assigned me to work with one of his chemistry postdocs, Chander Bahl, from whom I was to learn the necessary skills. Over the next year, I am afraid I did not make a great impression on Ray, as I struggled with the synthesis. During that year, Ray exhibited his characteristic patience, and was always supportive and sympathetic, and never critical of my lack of progress.

Finally, however, Ray realized that I needed more help if I was to complete the synthesis of the oligonucleotide. Far from feeling that everything had to be learned and completed in his lab, he immediately called his good friend and colleague Dr. Saran Narang, at the National Research Council of Canada. Ray and Saran arranged for me to travel to Ottawa, where I would spend two weeks getting intensive training. This was a wonderful thing to do, and a great and lasting lesson to me: one should never waste time by struggling endlessly at a difficult task when what you really need to do is to seek out the best expertise available and simply ask for help. The strategy worked, and on my return to Cornell I was able to compete the synthesis, and shortly thereafter John and I were able to radioactively label our synthetic piece of DNA and use it to detect the cytochrome c gene in yeast genomic DNA, as well as the corresponding mRNA in total RNA isolated from yeast.

One way that Ray influenced the directions his lab took was by selecting the students and postdocs who would join his lab. Around 1976-1977, Ray invited Rodney Rothstein to join the lab as a postdoctoral fellow. Rod had been a graduate student with Fred Sherman, and his arrival was therefore a continuation of the lab’s ongoing collaboration and exchange of ideas and personnel with the Sherman lab. Rod brought the new concepts and methods of yeast genetics to Ray’s lab. The timing was perfect, because methods for introducing DNA into yeast had just been developed in the nearby lab of Gerry Fink. This confluence of genetics and molecular biology was stimulating and, I believe, influenced many people from Ray’s lab and in the Cornell community. Ray loved having many different scientific threads woven together in his lab, which was a truly inter- disciplinary scientific environment.

After Rod’s arrival, I arranged to stay on in Ray’s lab as a postdoctoral fellow, instead of following the usual course of moving on to a new lab to learn new skills. This was an unusual step, but Ray was happy to have me stay, on the condition that I work on something completely different and thereby learn something new. This was easy. I was able to learn yeast genetics from Rod, and we began our collaborative studies on recombination in yeast while we were postdocs together in Ray’s lab. Both of us continued this line of research for many years thereafter. Ray, exhibiting his typical generosity of spirit, allowed us to take our projects with us when we left. He never competed with his former students, preferring to see them develop their independent research careers.

Ray had a small office, piled high with books and papers, with a door that opened directly into the lab. This afforded Ray the great advantage of being able to casually talk to people in the lab as he was going in or out of his office, and he could easily come out to ask about our progress whenever the mood struck him. However, his proximity to the lab did have a cost. Rod and I often talked about new ideas, and our discussions sometimes grew overly excited - I remember that on occasion Ray would emerge from his office into the lab to see what all the excitement was, and gently ask us to keep the noise level down to a more reasonable level.

After I left Ray’s lab in 1979, I, of course, saw him much less frequently. I returned to Cornell five or six times over the next twenty five years, and it was always a pleasure to meet with Ray and to be able to tell him about the latest results from my own lab as well as hearing about the developments in his. I was impressed when, during the later ‘80s and early ‘90s, he began to switch the direction of his laboratory research over to the molecular biology of rice, a field in which his lab became highly productive. This was also the period when Ray became heavily involved with the CUSBEA program and with science in China. 1998 brought Ray’s 70th birthday, and a memorable Symposium in Ray’s honor, attended by former students from around the world. Also there were Ray’s wife Christina and son Albert, whom I had not seen since the lab dinners at Ray’s house that brought a touch of family warmth to students far from home. Some years later there was a delightful luncheon in Boston attended by Ray and his family, and a number of his former students - Ray liked to keep in touch with us and keep track of our progress. I also remember a discussion in his office just three years ago–Ray would have been 76, but he was still fully engaged in his rice work, full of new ideas to pursue, and still interested in hearing about other things. Ray was not an effusive person; his manner was quiet and reserved.

His highest form of praise was that something you had said or done was “very interesting”. Ray had a remarkable number of students and postdocs who went on to do independent work that was indeed very interesting, and I know that he was in fact proud of all of us. I know equally that we are all grateful to have trained under and learned from such a wonderful scientist and person.
 
 Science in China C Vol. 52 (2): 108-110, 2009

 
 
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