“Hey!” Sam said, “I don’t like very nearly getting killed on a regular basis, either! It’s not like I go out of my way to find these problems!”
“Sometimes it sure seems like you do…”
Sam said, “I’m all right you know. But thanks for your concern.”
“I knew you were all right. Takes more than an evil mythical creature from Japan to kill you. Besides, you’re here to talk to me about the dog, aren’t you?”
Sam’s eyes widened. “You got the results!”
Aliana ignored him. It wasn’t every day that she had him desperate for something she had. “Let me guess, you picked up the dog while being chased by the evil monster?”
Sam said, “You know, you’d be surprised by how right you are.”
“No, I wouldn’t.”
Sam felt a lump in his throat. “You knew?”
“Not at first. But I did as soon as you mentioned being chased by some evil monster.”
Sam grinned. “Hey, you don’t think I’m crazy?”
“Sure I do, Sam. But in this case, you might be right.”
“What did you find?”
Aliana said, “Tell me about the dog. It’s really smart, isn’t it?”
“Aliana, just tell me what you know about the dog.”
“It’s a chimera.”
“From Japan?”
“No. A chimera was traditionally any sort of mythical beast that shares the spliced DNA of two or more species. Of course, with modern medicine, as well as strange chance occurrences, these two different genetic strands can naturally bind together.”
“You’re saying it’s no longer mythical?”
Aliana said, “Hell, it’s not even science fiction anymore.”
“How does it work?”
“Basically, an animal chimera occurs when a single organism becomes composed of two or more different populations of genetically distinct cells that originated from different zygotes involved in sexual reproduction. If the different cells have emerged from the same zygote, the organism is called a mosaic.”
“Zygotes?” Sam asked. “In English, please!”
“A zygote is the union of the sperm cell and the egg cell to achieve fertilization. As the egg is fertilized, the zygote begins as a single cell but divides rapidly in the days following fertilization. After this two-week period of cell division, the zygote eventually becomes an embryo.”
“I still don’t get it,” Sam said. “How does the single egg split into two distinctly different species?”
“Not all chimeras include different species. The most common human chimeras shared cells with distinct DNA from two or more people.”
“How does that happen?”
“Naturally, or through artificial assistance?”
Sam said, “Both.”
Aliana said, “The primary cause of chimerism in humans is during a bone marrow transplant. If a person required a bone marrow transplant, the donor’s erythropoietin — the cells that are responsible for producing new red blood cells — have a distinctly different DNA than the receiving person. As a consequence, the recipient becomes a chimera, having his or her normal DNA and someone else’s DNA in their bloodstream.”
Sam’s eyes narrowed. “But some people can be chimeras from birth?”
“Yes. When a mother is carrying fraternal twins, there is a high likelihood that one of the embryos might die very early in the pregnancy. It’s been estimated that this might happen as much as 20–30 percent of the time in the case of fraternal twins. Of course, it happens so early that the mother never realizes her loss. Instead, the other embryo can absorb some cells from the deceased one. The resulting baby ends up with two sets of DNA.”
“And artificially?” Sam asked.
“In research, chimeras are artificially produced by selectively transplanting embryonic cells from one organism onto the embryo of another, and allowing the resultant blastocyst — that’s one of the earliest cells to develop in the embryo — to develop as two or more distinctive DNA sets.”
Sam swallowed. “And scientists are actually doing this sort of stuff?”
“Yes,” Aliana replied. “And they have been since the early eighties!”
“You’re kidding me.”
“No. In fact, one of the earliest primate chimeras artificially produced were the rhesus monkey twins, Roku and Hex, with each having six genomes. They were created by mixing cells from four totipotent blastocysts, totipotent meaning an immature stem cell capable of developing into any cell in the body. The experiment kind of failed, because the cells never fused, but they formed individual organs with unique DNA.”
“Did anyone successfully develop an artificial chimera with more than one species?”
“They sure did. In 1984, the Institute of Animal Physiology in Cambridge, England successfully developed a Geep, by combining sheep embryos with goat embryos. But that’s not where the research ended.” There was something exciting, yet simultaneously disturbing about her enthusiasm.
Sam said, “Go on.”
“In August 2003, researchers at the Shanghai Second Medical University in China reported that they had successfully fused human skin cells and rabbit ova to create the first human chimeric embryos. The embryos were allowed to develop for several days in a laboratory setting, and then destroyed to harvest the resulting stem cells. In 2007, scientists at the University of Nevada School of Medicine created a sheep whose blood contained 15 % human cells and 85 % sheep cells.” She started to explain where current research was going, but Sam stopped her.
“Aliana… what other animals does the dog share its DNA with?”
Sam could imagine Aliana smiling as she answered him. “Not just the dog.”
Sam took a deep breath. “The dog shares DNA with the monster!”
“Exactly.”
“And what is the monster?”
“The deadliest of all creatures on Earth — homo sapiens.”
Sam stared at Caliburn trying to picture it as a chimera with shared human DNA. “There’s a man with dog DNA out there?”
“Not just dog DNA. Both creatures have a third DNA type.”
Sam couldn’t believe what he was hearing. “What’s the third type?”
“Octopus.”
“An octopus?” Sam closed his eyes for a moment, trying to picture the near mythical creature. “So I’m being hunted by man with octopus’s arms, and the whipping tail of a golden retriever?”
“Something like that…”
Sam stared a Caliburn. “But the dog looks normal. I mean, I’m looking at him right now, and even after being told that he’s part human, part octopus, he still looks just like any other dog.”
Caliburn shifted his gaze to meet Sam’s, recognizing the conversation had turned toward him.
Sam patted the dog, and said, “It’s okay, we’re just talking about how unique you are.”
Caliburn seemed to accept that, and rolled onto his back, with his tail somehow wagging side to side in the typically dangerous whipping fashion of a golden retriever.
Aliana said, “What are you trying to ask, Sam?”
Sam said, “I want to know why it doesn’t have a face of a man, and eight arms and legs like an octopus.”
Aliana laughed. “Chimerism is almost always undetectable without DNA tests. The exception to this is if they exhibit abnormalities such as male and female or hermaphrodite characteristics or uneven skin pigmentation.”
The skin pigmentation comment jogged Sam’s memory about Caliburn’s chameleon like camouflage in the T-Bird. “We got attacked by a group of highly trained mercenaries today.”
“A typical day in the Sam Reilly office.” Despite the humor in her statement, her voice had a steely cold edge to it.
Sam said, “The dog was in the car at the time. When we tried to escape, we couldn’t find him. It wasn’t until a good ten minutes after we had left the scene of the attack that Caliburn seemingly appeared out of thin air.”