"Frameshift" - читать интересную книгу автора (Sawyer Robert J.)

Chapter 10

Pierre had searched long and hard for an area to specialize in. His first instinct had been to do research directly into Huntington’s disease, but ever since the Huntington’s gene had been discovered, many scientists were concentrating on that. Naturally, Pierre hoped they would find a cure — and soon enough to help him, of course, if it turned out that he himself did have the disease. But Pierre also knew of the need for objectivity in science: he couldn’t afford to piss away what time he might have left chasing slim leads that would probably amount to nothing-leads that someone without Huntington’s would know enough to abandon, but that he, out of desperation, might devote far too much time to.

Pierre decided instead to concentrate on an area most other geneticists were by and large ignoring, in hopes that such territory would be more likely to yield a breakthrough that might indeed get him a Nobel Prize. He centered his research on the so-called junk DNA, or introns: the 90 percent of the human genome that did not code for protein synthesis.

Exactly what all that DNA did do no one was quite sure. Some parts seemed to be foreign sequences from viruses that had invaded the genome in the past; others were endlessly stuttering repeats — ironically, similar in structure to the very unusual gene that caused Huntington’s; others still were deactivated leftovers from our evolutionary past. Most geneticists felt the Human Genome Project could be completed much more quickly if the junk nine-tenths were simply ignored. But Pierre harbored the suspicion that there was something significant coded in some as yet undeciphered way into that mess of nucleotides.

His new research assistant, a UCB grad student named Shari Cohen, did not agree.

Shari was tiny and always immaculately dressed, a porcelain doll with pale skin and lustrous black hair — and a giant diamond engagement ring.

“Any luck at the library?” asked Pierre.

She shook her head. “No, and I’ve got to say this seems like a long shot, Pierre.” She spoke with a Brooklyn accent. “After all, the genetic code is simple and well understood.”

And so, indeed, it seemed to be. Four bases made up the rungs of the DNA ladder: adenine, cytosine, guanine, and thymine. Each of those was a letter in the genetic alphabet. In fact, they were usually referred to simply by their initial letters: A, C, G, and T. Those letters combined together to form the three-letter words of the genetic language.

“Well,” said Pierre, “consider this: the genetic alphabet has four letters, and all its words are three letters long. So, how many possible words does the genetic language have?”

“Four to the third,” said Shari, “which is sixty-four.”

“Right,” said Pierre. “Now, what do these sixty-four words actually do?”

“They specify the amino acids to be used in protein synthesis,” replied Shari. “The word AAA specifies lysine, AAC specifies asparagine, and so on.”

Pierre nodded. “And how many different amino acids are used in making proteins?”

“Twenty.”

“But you said there are sixty-four words in the genetic vocabulary.”

“Well, three of the words are punctuation marks.”

“But even taking those into account, that still leaves sixty-one words to express only twenty concepts.” He moved across the room and pointed to a wall chart labeled “The Genetic Code.”

Shari came over to stand next to him. “Well, just as in English, the genetic language has synonyms.” She pointed at the first box on the chart.

“GCA, GCC, GCG, and GCT all specify the same amino acid, alanine.”

“Right. But why do these synonyms exist? Why not just use twenty words, one for each amino?”

Shari shrugged. “It’s probably a safety mechanism, to reduce the likelihood of transcription errors garbling the message.”

Pierre waved at the chart. “But some aminos can be specified by as many as six different words, and others by only one. If synonyms protected against transcription errors, surely you’d want some for every word.

Indeed, if you were designing a sixty-four-word code simply for redundancy, you might devote three words apiece to each of the twenty amino acids, and use the four remaining words for punctuation marks.”

Shari shrugged. “I guess. But the DNA system wasn’t designed; it evolved.”

“True, true. Still, nature tends to come up with optimized solutions through trial and error. Like the double helix itself — remember how Crick and Watson knew they’d found the answer to how DNA was put together?

It wasn’t because their version was the only possible one. Rather, it was because it was the most beautiful one. Why would some aspects of DNA be absolutely elegant, while others, including something as important as the actual genetic code, be sloppy? My bet is that God or nature, or whatever it was that put DNA together, is not sloppy.”

“Meaning?” said Shari.

“Meaning maybe the choice of which synonym is used when specifying an amino acid actually encodes additional information.”

Shari’s delicate eyebrows went up. “Like, if we’re an embryo, insert this amino, but if we’ve already been born, don’t insert it!” She clapped her hands together. The mystery of how cells differentiated throughout the development of a fetus still hadn’t been solved.

Pierre held up his hand. “It can’t be anything as direct as that, or geneticists would have noticed it long ago. But the choices of synonyms over a long stretch of DNA — be it in the active portions, or in the introns — might indeed be significant.”

“Or,” said Shari, now pouting slightly at having her idea rejected, “it might not.”

Pierre smiled. “Sure. But let’s find out, one way or the other.”

A Sunday morning.

Molly Bond loved going over to San Francisco — loved its seafood restaurants, its neighborhoods, its hills, its cable cars, its architecture.

The street Molly was on was deserted; not surprising, given how early it was. Molly had come to San Francisco to attend the Unitarian fellowship there; she wasn’t particularly religious, and had found the hypocrisy of most of the clergy she’d met in her life unbearable, but she did enjoy the Unitarian approach, and today’s guest speaker — an expert on artificial intelligence — sounded fascinating.

Molly had parked a few blocks from the fellowship hall. The meeting didn’t start until nine o’clock; she thought she might go into McDonald’s for an Egg McMuffin beforehand — her one vice that she periodically but only halfheartedly tried to break was her fondness for fast food. As she headed along a steeply angled sidewalk approaching the restaurant, she noticed an old man up ahead at the side of the road in a black trench coat.

The man was bent over, poking with a walking stick at something lying at the base of a tree.

Molly continued along, enjoying the crisp early-morning air. The sky was cloudless, a pristine bowl of blue arching over the stuccoed buildings.

She was now only a dozen paces or so from the man in black. His trench coat was an expensive London Fog model, and his black shoes had recently been polished. The man was eighty if he was a day, but tall for a man that age. He was wearing a navy blue watch cap that pressed his ears against his head. He also had the collar of his trench coat turned up, but his neck was thick, with loose folds of skin hanging from it. The old guy was too absorbed in what he was doing to notice her approach. Molly heard a small whimpering sound. She looked down and her mouth dropped in horror. The black-clad man was poking at a cat with his stick.

The cat had obviously been hit by a car and left to die. Its coat, mottled white, black, orange, and cream, was smeared down the entire left side with blood. It had clearly been hit some time ago — much of the blood had dried to a brown crust — but it was still oozing thick red liquid from one long cut. One of the cat’s eyes had popped partway from its skull and was clouded over in tones of bluish gray.

“Hey!” Molly shouted at the man in black. “Are you crazy? Leave that poor thing alone!”

The man must have stumbled on the cat by accident, and had apparently been enjoying the pathetic cries it made each time he jabbed it with his stick. He turned to face Molly. She was disgusted to see that his ancient bone-white penis, erect, was protruding from his unzipped trousers, and that his other hand had been on it. “Blyat!” cried the man in an accented voice, his dark eyes narrowing to slits. “Blyat!”

“Get out of here!” Molly yelled. “I’m going to call the police!”

The man snapped “Blyat” at her once more, then hobbled away. Molly thought about going after him and detaining him until the police could arrive, but the very last thing in the world she wanted to do was touch the vile character. She loomed in to look at the cat. It was in terrible shape; she wished she knew a way to put it quickly out of its misery, but anything she might try would probably just torture the poor creature more. “There, there,” she said in soothing tones. “He’s gone. He won’t bother you anymore.” The cat moved slightly. Its breathing was ragged.

Molly looked around; there was a pay phone at the end of the block. She hurried over to it, called directory assistance, and asked for the SPCA emergency number. She then dialed that. “There’s a cat dying at the side of the road,” she said. She craned her neck to see the street signs. “It’s just off the sidewalk on Portola Drive, a half block up from the corner of Swanson. I think it was hit by a car, perhaps an hour or two ago… No, I’ll stay with the animal, thanks. Thanks ever so — and please hurry.”

She sat cross-legged on the sidewalk next to the cat, wishing she could find it in her heart to stroke the poor animal’s fur, but it was too disgusting to touch. She looked down the street, furious and distraught.

The black-clad old man was gone.