“The dragons must save themselves,” Wind Blossom pronounced. Tieran bit back a retort as he noticed the look of intense concentration on her face.
“Are you saying that they will build an immunity?” Emorra asked as Wind Blossom’s silence lengthened. “But we have no way of knowing the mortality rate of this infection.”
“We do not know enough about this illness,” Wind Blossom declared. “The people in the future know about it, but we do not.”
She paused to let the others comment, but Tieran and Emorra only nodded in wary agreement.
“We know how to alter the genetic code of the dragons, and we know how to create specimens and map genetic material, but they do not.”
Again, she paused for comment and again, there was none.
“They cannot bring their knowledge to us without also bringing the infection itself,” Wind Blossom continued. “So we must bring our knowledge to them.”
“But M’hall said the dragonriders couldn’t-” Tieran protested.
At the same time Emorra cried, “That would infect our dragons, too!”
Wind Blossom rapped the chalk on the blackboard, the noise echoing harshly around the room, until the other two were silent.
“We will teach them,” she declared. “We will teach them how to collect specimens, use the mapper, and construct genetic code.”
Tieran sat back again in his chair, his brows furrowed thoughtfully. Beside him, Emorra gnawed her lip unconsciously, her eyes closed in concentration.
“You mean we’ll make classrooms?” Tieran asked after a while. “To teach people chemistry, biology, and technology?”
He shook his head. “I don’t see how we can do it.”
Wind Blossom frowned at him. “Teach them how to identify the infection and how to engineer an antigen,” she said. “That is not hard.”
“So you mean to explain everything in layman terms,” Emorra said. She cocked her head in consideration. “It could work.”
Tieran gave Wind Blossom a penetrating stare. “It bothers me that there has never been a report of illness in the fire-lizards. I thought it was an axiom that an ecosystem will always evolve.”
“You’re saying that something should have come up in eight years?” Emorra asked, frowning in disbelief.
“No, in fifty years,” Tieran answered. “In the same time, we’ve had a major epidemic nearly wipe us humans out, and yet the fire-lizards, dragons, watch-whers, wherries, and, for all I know, tunnel-snakes seem not to have suffered from any form of viral, bacterial, or fungal assaults.”
“I see what you mean,” Emorra replied.
“You are forgetting Pernese genetic code,” Wind Blossom said, shaking her head in disappointment.
“No, I’m-” Tieran said hotly, only to cut himself off. “Oh,” he admitted, going slowly pink, “I am.”
“What about it?” Emorra asked, looking from Tieran to Wind Blossom and back for an explanation. Wind Blossom gestured to Tieran to answer.
Tieran took a breath. “Well, you have to remember how Pernese genetic code differs from ours.”
“Mmm?” Emorra murmured, gesturing for him to continue.
“Well, our genetic code is composed of two strands of DNA joined in a double helix,” Tieran said. “Whereas Pernese genetic code is composed of three strands of what we call PNA joined in a twisted triangle.
“Two of the strands complement the major strand,” he went on. He walked up to the blackboard and gestured to Wind Blossom, who surrendered the chalk. With a nod of thanks, Tieran turned to the blackboard and began to draw. He drew a series of triangles stacked on top of each other, each twisted slightly out of line with the one preceding it. The corners of the triangles he filled in with dots. He proceeded to label the dots: A, A’, N; B, N, B’; C, C’, N.
On another part of the board he drew the long-familiar double helix of DNA, creating a twisted ladder and labeling the “rungs” on one half of the ladder, A, C, G, T while labeling the other side of the ladder T, G, C, A.
Tieran jabbed a finger at each of the letters in turn. “A stands for adenine, C for cytosine, G for guanine, and T for thymine.
“They are grouped in threes and each group of three is called a codon,” he said. “Each codon codes either an amino acid or is a special marking signifying the start or end of a genetic sequence.
“Because there are four possible amines taken three at a time, there are sixty-four possible variations, but terrestrial DNA only encodes twenty amino acids along with one start and one stop codon.”
“I remember now,” Emorra said. “It always seemed wasteful.”
“It allows room for expansion,” Tieran said. “It also allows for errors or mutations to creep in. Typically there are six to seven hundred mutations in each newborn.”
“So that’s why we get sick,” Emorra remarked.
“More because the viruses and bacteria that attack us mutate than because of our mutations,” Tieran replied. “But sometimes it is our mutations that cause problems.”
He turned to the twisted triangle of the Pernese genetic code.
“Here, A, B, and C are only simple names for the different Pernese amines that make up their genetic material,” Tieran said. He pointed to the dot marked A’. “A-prime, here, is merely the amine that binds to A, and so on for B-prime and C-prime.”
“So what’s N?” Emorra asked. “Null?”
“Exactly,” Tieran agreed. “One of the fundamental differences between Pernese genetic material and terrestrial DNA is that instead of having two strands that are mirror images of each other, PNA has a main strand and two other strands that alternately mirror the main strand.”
“So does PNA have four pairs in a codon?” Emorra asked.
Tieran shook his head. “No, just three like our DNA.”
Emorra raised her eyebrows at that. “So that means that PNA can only code twenty-seven variations.”
“That’s right,” Tieran said. “Of course, we only need twenty-two out of the sixty-four that can be coded with DNA, so PNA is actually more efficient.”
“They code twenty amino acids?” Emorra asked, looking at Wind Blossom.
“No, they code twenty-three amino acids,” Wind Blossom corrected.
“They also code two different START and STOP sequences,” Tieran remarked. “That leaves no spare codings.”
“The combination of the three strands makes it harder for PNA to be split,” Wind Blossom said.
“Wouldn’t that be bad?” Emorra asked. “As I recall, whenever genetic material is accessed, the strands are separated and a segment is copied.”
“That’s not exact,” Wind Blossom replied chillingly. “But it is sufficient for our current discussion.” She waved for Tieran to continue. Stifling an impulse to argue with her, he turned back to Emorra.
“The fact that Pernese genetic material-”
“Didn’t you say to call it PNA?” Emorra interjected.
“-PNA, then, is harder to separate means that mutations in the PNA are less likely than in terrestrial DNA,” Tieran said. He looked at Wind Blossom and asked, “Is that why you think there haven’t been any illnesses? Because PNA is so much less prone to mutations than DNA?”
“It is just as prone,” Wind Blossom corrected. “However, the rate is slower.”
Tieran waved away the correction as meaningless.
“There is a big difference,” Wind Blossom persisted. “It means that over time, PNA will have mutations.”
“It still means that in the same period of time there will be more mutations in DNA than in PNA,” Emorra said, coming to Tieran’s defense.
“That’s not all,” Tieran said. “The very resistance to change means that PNA is less able to deal with unwanted mutations.”
“Oh, I think PNA deals with mutations quite admirably,” Wind Blossom said dryly.