..... After going through immigration, the small group of Americans gathered under the clock in the Charles DeGaul international terminal to wait for Prof. Bengston. "Hey, I got to sit next to a couple of unusual guys," began Mary Lou. "Long ago they had been college roommates, and they were on their way to attend a convention here. A guy, who insisted I call him Dr. V, sat on one side of me. It seemed like I've known him all my life. On the other side, was a really handsome doctor who sure looked like Eric Forrester, but he had the name of Dr. Romance. And get this - he's a gynecologist!" "Well, let me tell you a better one," Cheryl chimed in, circumnavigating Mary Lou's reference to a soap opera character. "I sat between two other doctors - Smith, a psychiatrist, and Jones, a proctologist. They said they were specialists in odds and ends!" Soon, the jovial group was ensconced in a small hotel: Cheryl and Mary Lou were settled in room #1 and the guys in a couple of other rooms. They then decided that next on their agenda was a four block walk past Notre Dame and over the bridge to the University to meet their host. Prof. Cluseau showed them their lab "hang-out" that they could use during their stay. It was a small, rather antiquated and dusty set of rooms up under the 5th floor eaves of the Pasteur Institute.

..... To her delight, Mary Lou managed to get Jimmy to help her, while the others worked together on a project requiring more hands. The two-some were setting up a demonstration that would prove that the gal-operon was being transferred from one strain of E.coli to another. To nail it down, they wanted to tag the two cultures with a gene that was independent of the gal-operon. They chose resistance to the antibiotic tetracycline. This way they could unambiguously show that the transduction went into a genetic "background" that was tetracyline sensitive (tet^S). So they looked around the lab and "borrowed" two cultures: one was E.coli (lambda) and was gal⁺ and tetracyline resistant (tet^R), and the other was lambda-free, tet^S, but streptomycin resistant (str^R), and had a lot of other different auxotrophic mutations. They were only interested in the fact that the cells were gal^-, and were not concerned with the fact that these cells were also unable to make threonine, tryptophan, histidine, arginine, methionine, leucine, proline, and several other amino acids and bases. All they had to remember to do was add all those nutrients to the medium so that the cells would grow. Once the lysogenic culture was growing well, Jimmy shined a very strong UV light at the culture, while Mary Lou plugged her ears thinking that something might explode since she had heard that this UV-induction would cause the bacteria to burst.

..... Then the lysate was treated with chloroform, and the supernate was mixed with the growing culture of the gal^- cells, serially diluted and then plated on MacConkey plates that contained the sugar galactose AND streptomycin. Even Mary Lou paid attention when Prof. Bengston described how the str would prevent any of the lambda donors from growing, and the special type of agar would detect any transductants because the colonies would grow up red. That was because when E.coli metabolize a sugar, they make lots of different organic acids, which lower the pH and, since there is a pH indicator in MacConkey agar, the colonies turn red. So if any colonies can use galactose, they grow as red colonies. Any cells that were not infected with lambda-dg would grow up a pale pink. (MacConkey agar has all the amino acids and bases in it, by the way.)

..... Now it should be pointed out that because Mary Lou was continually sneezing from the dusty venue, she finally asked for permission to leave. This would allow her to search out Nirvana Crump at her fashion house, which was only a couple of Metro stops away.

..... After she left, Jimmy considered making a control MacConkey plate with both streptomycin and tetracyline in it.

..... In her new dress from the K-Mart sale rack back in Las Vegas' Fashion Show Mall (very similar to the design of Norfolk's MacArthur Center), Mary Lou got off the Metro, and on the way up to street level she saw a sign written in five languages: "Beware of Pick-Pockets!" She reached into her dress pocket and extracted her room key and tightly held it with its tag imprinted with a big "1". She then sashayed up the avenue toward Nirvana's place, where, along the way, she saw a notice that an afternoon show was about to start. Ah, there was the N. Crump sign, but the sidewalk was roped off, and she could not get near the main door because of throngs of gawking people. But she saw a few people slipping into a side door and decided to follow their lead. While it would be daunting for most people without at least a rough knowledge of French to find their ways, Mary Lou marched confidently on through back corridors until she came to a door through which most of the crowd was going. Alas, it was a dressing room and not where she wanted to be. She ducked out to tried another door. "Oh, the show must have started," she thought to herself when she saw it was dark except for a few spotlights. There seemed to be an aisle down which she could walk. Lots of flask bulbs popped blinding her so that she couldn't see at all where she was walking. Fearing herself lost, she retreated, and - to make the story short - finally found a door to the seating area. There she sat in her reserved seat next to Nirvana, who was trying to hold back laughter. "Did I miss anything?" Mary Lou whispered to her hostess. "Not much, only the first one - a real master-piece," replied Nirvana. "Oh, here comes the next presentation."

..... The next morning, to the Americans' surprise, a note arrived from Nirvana inviting them to banquet that evening at her apartment. For the remainder of the morning and early that afternoon, the group worked in lab, again leaving Mary Lou to fend for herself. Jimmy checked in on the experiment done with her. He was happy to find a few red colonies on the MacConkey plates, and went to tell the others that he and Mary Lou had completed their part of the exhibit they were putting together. When Jason and Cheryl came over to look, they told Jimmy that he had made a beautiful exhibit. "But what are these plates over here?" Cheryl asked. "Oh," Jimmy confessed, "it was something that didn't work right. Those are some colonies - both red and pale pink - that grew up on media that contained both str and tet."

..... Jason looked curiously at the plates, and walked away silently. Then he turned around and asked Cheryl and Jimmy to help him test those colonies for some of the other background genetic characteristics of the receiving strain. Of course all of the red colonies were now gal⁺, and all of the pink colonies were gal^-, but had the gal^- colonies picked any other genes? What they found was that the pink colonies were a very strange and mixed batch. Some were now threonine⁺, or proline⁺, etc. It was as if lambda had become a generalized transducing phage.

..... They then turned their attention to the gal⁺ recipients. Those were also a mixed bag of "plusses", which not only received the gal-operon, but one of the hundreds of other genes also. This called for a sit-down and a good "think" at one of the local bistros.

..... Prof. Cluseau, an avid follower of the continuing battles between Nirvana Crump and her "ex", the famous Ronald, invited himself to the dinner at the Crump apartment. There, over a preliminary glass of wine, Nirvana rose to toast a very famous young woman. Everyone was shocked when she turned and raised her glass to Mary Lou. "Allow me to show you the front page of the fashion section in today's Le Monde." There, big as life, was a quarter-page photo of Mary Lou, clutching her "1" and trapsing down the runway in her K-Mart special. "I think little more than a brief translation need be said." Rough translation: "Finally the House of Crump produces a practical dress that most French women wouldn't be embarrassed to wear. Already orders for 20,000 were placed in the first hour after the showing. Orders continue to flood in." And what a surprise it was to Cheryl, who was tapped on the shoulder by the proctologist, Dr. Jones, who raised his glass in toast: "Bottoms up!"

..... Later the merry conversation digressed to the more prosaic scientific level. Prof. Cluseau wondered aloud whether or not the auspicious surroundings had inspired these young people. "You know, my young friends, it was in that very laboratory that lysogeny was discovered. That lab, and one at Cal Tech, can be said to have started the modern field of virology. Now I am wondering what of consequence you have discovered." What had they discovered? Hint: it was not that lambda is a generalized transducer - it was found not to be. But how could all those various mutations in the recipient cells be reversed one at a time.

As the group saw the sights of Paris, Cluseau put a couple of graduate students on the problem and found themselves even in deeper mystery. They took a look at only one type of reverse mutation. They isolated all the pro⁺ that they could find, and then mapped the location of that pro⁺ in each of the clones. What they found was that the pro⁺ was not where the pro-operon usually resided. In fact, each of the many reversed-mutants seemed to have pro⁺ in different places, and every single clone was tet^R! What befuddlement! What is going on? HELP! (Hint: think: "Nobel Prize!")

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