The Power of ‘Junk’
||The genome of a South American species of opossum is proving useful in comparative studies with the human genome.
Thanks to new genetic findings in marsupials,
researchers have learned that most innovations
leading to the human genome sequence lie in areas that until recently were labeled “junk” DNA. An international team supported
by NHGRI announced in the May 10 issue of Nature the publication of the first genome sequence of a marsupial—specifically,
one belonging to a South American species of opossum. By comparing the marsupial genome to genomes of non-marsupials, like humans, researchers are able to understand better the way mammalian
genomes have evolved over millions
of years. The key finding from the comparison: the vast majority of recent genetic innovation in our genome lies not in protein-coding genes, but in regions that don’t contain genes at all, leading to their “junk” moniker. Marsupials are the closest living
relatives of placental mammals, offering a unique view of our own genome’s evolution.
More Testing Needed
Two recent findings from NIH researchers point to worrisome rates in necessary testing and treatment. In an online report in the journal
, researchers, led by NCI’s Dr. Nancy
Breen, showed that after rapid increases in reported use of mammography by women in the U.S. since 1987, the percentage of women 40 and older who reported having a mammogram
within the last 2 years slipped from 70 percent in 2000, to 66 percent in 2005. Though this is a relatively small decline, researchers said the drop is still cause for concern because it signals
a change in direction. The findings were based on a survey of about 10,000 U.S. women over age 40 conducted by the CDC.
And Treatment, Too
Meanwhile, a recent survey conducted by NIDA and NIAAA showed that only 8 percent of people
identified as drug abusers and fewer than 40 percent of those diagnosed with drug dependence
have ever had any kind of intervention or treatment. These survey results, published in the May issue of the Archives of General Psychiatry,
also show that rates of drug abuse and dependence are generally higher among certain populations, including men, respondents ages 18 to 44 years and people who have never married. Researchers said these findings suggest certain groups are more vulnerable and should therefore be targeted for early intervention efforts.
Defining Bipolar Disorder
In the same issue of the Archives of General Psychiatry,
an NIMH-funded study reported that bipolar disorder may be both inaccurately characterized
and improperly treated. Using data from a nationwide survey of mental disorders among 9,282 Americans ages 18 and older, researchers
determined that the illness may be more accurately characterized as a “spectrum” disorder
because it manifests itself in multiple ways. And while the study showed most respondents with the illness reported receiving treatment of some kind, not everyone received treatment considered
optimal for bipolar disorder. Up to 97 percent of those who had some type of bipolar illness said they had coexisting psychiatric conditions—
like anxiety, depression or substance abuse disorders—and many received treatment for these conditions instead of for bipolar disorder.
The study points to the need for better screening tools and procedures for identifying the disorder, researchers said.
However, this month NIMH also reported more positive news for bipolar disorder. Research published
online in Molecular Psychiatry revealed results from the first genome-wide study of the illness. It showed that the likelihood of developing
the disorder depends in part on combined, small effects of variations in many different genes in the brain, none of which is powerful enough to cause the disease by itself. Targeting
the enzyme produced by one of these genes, called DGKH, could lead to the development of new, more effective medicines.
Visualizing the ‘Claw’
Finally, electron tomography, an advanced imaging
technique, has allowed NCI researchers to visualize an “entry claw,” a structure formed between the human immunodeficiency virus and the cell that it infects. This ability to see virus-host interaction at the molecular level not only gives researchers insight into how HIV and related
viruses interact with proteins on the surface of cells and enter the host cells to integrate their DNA, but also gives clues as to how to improve the design of anti-HIV therapy. Further, it demonstrates
that tools like electron tomography have the potential to help scientists see the subcellular
effects of many different diseases, including
cancer. The findings were published in the May 4 issue of PLoS Pathogens. —