Jumping genes, or transposons, are small pieces of DNA that
have the unusual ability to copy and insert themselves in random places within
a genome. These genes—long known as junk DNA—were thought to be nothing more than
genomic parasites, but research is beginning to show their importance in
evolution.
Most cells in our body contain DNA, a molecule composed of a
double helix that carries the genetic instructions required for life. (Mature
red blood cells are the only ones that lack DNA, having gotten rid of it to
pack themselves full of more hemoglobin, an iron-rich protein). For cells to
access the information contained in DNA, they must transcribe it onto a related
molecule called RNA. Despite that the same DNA is in almost every cell, not
every cell is expressed in the same way, otherwise we would be one giant blob
of undifferentiated matter.
Jumping genes were first discovered by geneticist Barbara
McClintock in the 1940s. At the time, most scientists dismissed them, but McClintock
suggested they might play a regulatory role by determining which genes are
turned on and when.
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| Barbara McClintock |
Transposons have been found to jump across plants, animals
and fungi as well. The process is known as horizontal transfer, as opposed to
the normal parent-offspring transfer, and has had an enormous impact on
mammalian evolution. For example, 25% of the genome of cows and sheep is
derived from jumping genes.
One such jumping gene is called LINE1, abundant in almost
all genomes of mammals. It’s repeated half a million times in the human genome,
making up nearly a fifth of the DNA in every cell. Studies of mouse embryos
have shown that LINE1 is especially active during early development of the
organism, suggesting that the segment might play a key role in coordinating the
formation of cells. Researchers believe that LINE1 RNA particles act as a
molecular “glue,” switching off the two-cell stage of early development and
jump-starting it to the next phase.
There are many different types of jumping genes, including
some that drive the evolution of genomes, thereby creating more genetic
diversity in a species.
In my book COLD HORIZON, Lindsey Coulson is a chemist who studies jumping genes.
Two years ago, Lindsey Coulson lost her sister on K2, the
second highest mountain on earth. Searching for answers, she sets out to climb
the Savage Mountain. Mountaineer and freelance writer Ty Galloway has assembled
a small team to conquer K2 and welcomes the esteemed climber. But K2 is a force
unto itself, as is Lindsey. Both will test his limits. Both will test his
heart.
“Blending romance, suspense, adventure, and action, it
really was a great thrill ride of a book and one that I gladly recommend.” ~ Jamie,
The Romance Studio
Excerpt from Cold Horizon
Lindsey scooped more snow into the pan and set it atop the
stove. Ty was all business with her, giving no indication that they were more
than friends. A few times she had to stop herself from touching him, or leaning
into him, or standing too close. Not that there was any big reason to keep it a
secret. Still, she was tempted to kiss Galloway in full view of Fiske if only
to get the jerk off her case.
“Ty, you still planning to go to the South Pole?” Beck
asked.
“Maybe. It depends on my schedule.” He drank from his water
bottle, flinching from the hot liquid.
“You wanna go?”
“I’m interested. Let me know when/if you settle on a date.
Maybe you should come too, Lindsey.”
“Why’s that?” she asked.
“It’s the last great frontier. A real feather in any
explorer’s cap.”
“I thought space was the last frontier,” Packer said from
his spot just outside their circle.
Beck ripped open the wrapper on a candy bar. “We’re nearly
in space on this mountain.”
Packer laughed. “That’s for damned sure.”
Fiske took a bite of a power bar. “Mountains are more
difficult,” he said around the food in his mouth. “The South Pole is just
dragging a sled for miles.”
“It’s all about the mind, Fiske.” Beck broke off a piece of
chocolate and popped it in his mouth.
“Seeing if you have the mental capacity
to do it.”
Was it Lindsey’s imagination, or did Beck’s voice hold a
hint of sarcasm?
If Fiske noticed, he gave no indication, and said, “I think
it a waste of time. Climbing has better goals. Will you climb while you are
there?”
Ty shook his head. “No. It would be a trek across ice.”
Beck’s attention shifted to her. “So, what do you think?”
If for no other reason than to irritate Fiske, she answered,
“I’ve always wanted to visit Antarctica.”
Ty gave her a sidelong glance, a wicked gleam in his eyes. “Then
you should come.”
She smiled and looked away before she did a happy jig over
the open invitation.
Packer moved to stand beside her and said, “But please, by
all that’s holy, don’t go near any strange creatures and try to study their
DNA. We all know what happened in ‘The Thing.’”
“Because that was a completely true story,” Ditch said in a
dry tone.
“Did you know that the dot on an ‘i’ is called a tittle?”
Packer chuckled.
“Do you get whiplash?”
“From what?”
“Your ADD,” Ditch said.
Lindsey looked over her shoulder at Packer. “That movie
wasn’t really that farfetched. The alien functioned like a virus, infecting its
host and taking over. Viruses like to jump around, and we humans are ripe for
the picking because we like to take a lot of risks. We eat things we probably
shouldn’t, and we poke around in places where maybe we should stay away.”
Packer’s eyes widened. “Like here?”
Lindsey smiled. “We do like to push those boundaries. It’s
evolution, baby.”
Copyright ©
2019 K. McCaffrey LLC
COLD HORIZON is available in ebook and print.
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