It Takes Two: A Year of Twin-formation and the Effects
of Spaceflight on Individuals
What could twins tell us about the effects of spaceflight on humans? NASA
hopes to find out. In a world as diverse as ours, it can be easy to forget that
most humans are approximately 99.5 percent genetically identical. Identical, or
“monozygotic,” twins are nearly 100 percent identical. What accounts for the
differences we know exist? The remaining 0.5 percent of genetic real estate,
which on the surface seems like a small amount, codes nearly all the
characteristics that make us unique individual humans.
The complexity of individual differences makes it difficult for scientists to
predict responses to disease, treatments or environmental stressors that apply
across the entire human population. This is especially relevant to scientists
studying the effects of spaceflight on the human body. Spaceflight may magnify
the difference between individuals because it exposes crew members to stressors
such as radiation, microgravity, isolation, confinement, and altered light/dark
cycles. If this might be true for individuals who are genetically different,
what does this mean for twins who are nearly identical?
A DNA double helix carries the codes for regulating
the activities of cells. Differences in DNA, RNA and proteins are what make
individuals unique.
Image Credit: Jonathan Bailey, NHGRI
Image Credit: Jane Ades, NHGRI
A telomere is the end of a chromosome that protects
the interior of a chromosome from damage during cell division. Each time a cell
divides, telomeres become shorter. Eventually, telomeres become so short that
the cell dies or becomes cancerous.
Image Credit: Darryl Leja, NHGRI
A study new to NASA, which will take place throughout NASA’s one-year
mission beginning in March 2015, should help scientists better understand
the impacts of spaceflight on the human body through the study
of a pair of identical twins. Astronaut Scott Kelly will
spend one year in low-Earth orbit aboard the International
Space Station while retired astronaut Mark Kelly, his
identical twin, will remain on Earth. The twins’ similarity provides scientists
with a reduced number of variables and an ideal control group, both important to
scientific investigation. Study investigations will be selected as part of the
Human
Exploration Research Opportunities solicitation developed and managed by
NASA’s Human
Research Program and the National Space Biomedical Research Institute.
While the study is a supplemental objective of the one-year
mission, it will support the overarching mission investigations that will
likely center around medical concerns such as increased intracranial pressure
associated with microgravity, behavioral health and performance issues
associated with prolonged isolation, challenges associated with exposure to the
space radiation environment, various physiological changes like bone
and muscle loss, changes in the sensorimotor
system, and changes to nutritional status.
The twin study will also introduce to space physiology a rapidly growing
field of research called –omics. Omics is a broad area of biological and
molecular studies that, in general, means the study of the entire complement of
biomolecules, like proteins (proteomics); metabolites, the end products of
metabolism, (metabolomics); or genes (genomics).
“The term –omics means ‘everything’,” says NASA astronaut Kate Rubins, Ph.D.
“For example, rather than observing a few genes at a time as researchers did in
the early 1990s, scientists in the field of genomics investigate the activity of
all of the genes in the genome simultaneously. It’s like taking a snapshot of
all of the activity inside a cell.”
NASA’s solicitation
for proposals related to –omics studies of the twins was released in July
2013 and closed in September 2013. Selections will take place in January 2014.
NASA expects to fund up to ten investigations.
“This study will allow us the opportunity to form a team of experts that
collectively will cover all disciplines within the –omics field,” says Graham
Scott, Ph.D. and chief scientist at the National Space Biomedical Research
Institute. “By conducting an integrated –omics study, we can simultaneously
overlay what we observe in the DNA, RNA, proteins and metabolites and form a
rich picture of what is going on with Scott [Kelly] as opposed to Mark.”
The twins’ –omics responses will reveal to researchers what impact
spaceflight has on humans at the biomolecular level. They should also shed new
light on whether individuals are more susceptible to certain adverse conditions
which could threaten their health and, ultimately, the mission.
The investigations could also include a study of the length of the twins’
telomeres, the caps at the end of chromosomes that protect its most important
parts. Each time a cell replicates, its telomeres slightly shorten, although an
enzyme called telomerase can partially repair the telomeres—especially when we
are young.
“This shortening is associated with aging and stress,” says Rubins.
Eventually your telomeres shorten to the point that they no longer protect
the chromosomes and the cell will either die or potentially malfunction,
possibly causing cancer or other diseases. The space environment may also
directly damage the telomeres or somehow affect the activity of telomerase, both
of which may cause telomeres to shorten prematurely. The difference in the
length of the twin’s telomeres after Scott’s year in space may provide valuable
data about the effects of spaceflight on humans.
“These –omics- and telomere-focused investigations will allow us to identify
specific biological pathways that are being affected by spaceflight,” says
Scott. “If we can understand what pathways are being affected and how they
correlate to the physiology of the astronaut, we are on the road to designing
individualized biological countermeasures for each astronaut.”
This is critical when it comes to long-duration missions like those to
asteroids and Mars as long-term exposure to radiation and microgravity will
amplify the effects of spaceflight even further.
Ultimately, the fact that the Kelly twins are nearly genetically identical in
that small 0.5 percent window that makes most of us different will help NASA
understand the specific biological effects of spaceflight. Their similarities
may potentially enhance individual astronaut performance and safety now and
years into the future.
NASA, NSBRI Select 26 Proposals to Support Crew Health
on Deep Space Missions
NASA's Human Research Program (HRP) and the National Space Biomedical
Research Institute (NSBRI) will fund 26 proposals to help investigate questions
about astronaut health and performance on future deep space exploration
missions. This research may help protect astronauts as they venture farther into
the solar system than ever before to explore an asteroid and, eventually,
Mars.
The selected proposals are from 16 institutions in eight states and will receive a total of about $17 million during a one- to three-year period. The 26 projects were selected from 123 proposals received in response to the research announcement "Research and Technology Development to Support Crew Health and Performance in Space Exploration Missions." Science and technology experts from academia and government reviewed the proposals. NASA will manage 21 of the projects and NSBRI will manage five.
The selected proposals will investigate the impact of the space environment on various aspects of astronaut health, including visual impairment, behavioral health, bone loss, cardiovascular alterations, human factors and performance, neurobehavioral and psychosocial factors, sensorimotor adaptation and the development and application of smart medical systems and technology.
HRP and NSBRI research provides knowledge and technologies that may improve human health and performance during space exploration. They also develop potential countermeasures for problems experienced during space travel. The organizations' goals are to help astronauts complete their challenging missions successfully and preserve their long-term health.
HRP quantifies crew health and performance risks during spaceflight and develops strategies that mission planners and system developers can use to monitor and mitigate the risks. These studies often lead to advancements in understanding and treating illnesses in patients on Earth.
NSBRI is a NASA-funded consortium of institutions studying health risks related to long-duration spaceflight. The Institute's science, technology and education projects take place at approximately 60 institutions across the United States.
For a complete list of the selected principal investigators, organizations and proposals, visit:
For information about NASA's Human Research Program, visit:
For information about NSBRI's science, technology and education programs, visit:
For information about NASA and agency programs, visit:
The selected proposals are from 16 institutions in eight states and will receive a total of about $17 million during a one- to three-year period. The 26 projects were selected from 123 proposals received in response to the research announcement "Research and Technology Development to Support Crew Health and Performance in Space Exploration Missions." Science and technology experts from academia and government reviewed the proposals. NASA will manage 21 of the projects and NSBRI will manage five.
The selected proposals will investigate the impact of the space environment on various aspects of astronaut health, including visual impairment, behavioral health, bone loss, cardiovascular alterations, human factors and performance, neurobehavioral and psychosocial factors, sensorimotor adaptation and the development and application of smart medical systems and technology.
HRP and NSBRI research provides knowledge and technologies that may improve human health and performance during space exploration. They also develop potential countermeasures for problems experienced during space travel. The organizations' goals are to help astronauts complete their challenging missions successfully and preserve their long-term health.
HRP quantifies crew health and performance risks during spaceflight and develops strategies that mission planners and system developers can use to monitor and mitigate the risks. These studies often lead to advancements in understanding and treating illnesses in patients on Earth.
NSBRI is a NASA-funded consortium of institutions studying health risks related to long-duration spaceflight. The Institute's science, technology and education projects take place at approximately 60 institutions across the United States.
For a complete list of the selected principal investigators, organizations and proposals, visit:
For information about NASA's Human Research Program, visit:
For information about NSBRI's science, technology and education programs, visit:
For information about NASA and agency programs, visit:
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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