SAS Frontiers
Less Sleep Means Less Learning
In the May/June issue of the Journal of Learning,
SAS biologist Ted Abel explains that if
a mouse sleeps after completing a task, it will remember
the task much better than a mouse that doesn’t sleep. “Memory
consolidation happens over a period of hours after training
for a task, and certain cellular processes have to occur
at precise times,” he said. “We set out to pinpoint
the specific window of time and area of the brain that are
sensitive to sleep deprivation after learning.”
Sleep deprivation during a five-hour window immediately
following learning impairs spatial orientation and recognition
of physical surroundings, known as contextual memory. Recollection
of facts or events, known as cued memory, was not affected.
Because the hippocampus is key to contextual memory, the
findings provide evidence that sleep helps regulate neuronal
function in that part of the brain. Biology major Elizabeth
Heller, C’02, was a co-author of the study.
Enzyme Could Treat Sex Disorders
The enzyme arginase II, which can short circuit a biochemical
pathway leading to sexual arousal in men, is also present
in women. And it might be a promising target for new remedies
to treat sexual dysfunction in women.
Scientists from Penn with colleagues from two other universities
have mapped out arginase II’s three dimensional structure,
easing the job of creating drugs to disable it. The findings
appeared in the July 22 issue of Biochemistry. “We
identified the enzyme in the male genitalia six years ago,” lead
scientist David Christianson said. “Since
then, we’ve wondered whether arginase might also be
present in the female genitalia, and if so, whether it might
similarly play a role in female sexual dysfunction.” In
studies with female rabbits, the researchers found the enzyme
in their genitalia. Healthy sexual function relies on a biochemical
cascade as carefully orchestrated as any courtship ritual.
That complex chemistry is sometimes derailed by arginase.
Unlike Viagra, which was developed for erectile dysfunction,
remedies that put arginase out of commission may offer hope
for both sexes. “We’ve wondered whether arginase
inhibitors could enhance smooth muscle relaxation in the
female genitalia, leading to sexual arousal,” stated
Christianson, the Roy and
Diana Vagelos Professor in Chemistry and Chemical Biology. “It now appears
that this might be the case.”
Kids Not Meeting Expectations? Try Religion.
Recent studies have identified how religion can keep disadvantaged
youths out of trouble, especially in the inner city. Now
a study from Penn’s Center for Research on Religion
and Urban Civil Society (CRRUCS) shows that religion can
benefit “advantaged” suburban youths too. Mark
Regnerus, a visiting CRRUCS fellow, identified teens
who failed to live up to expectations despite their privilege
and compared the effect of religion in their lives with the
effect of religious influences on young people who managed
to stay out of trouble. His study, Living Up to Expectations:
How Religion Alters the Delinquent Behavior of Low-Risk Adolescents,
shows that ining a church helps kids steer clear of drinking,
drugs, and other problems because they tap into the support
systems of fellow churchgoers. “Both lower church attendance
and lesser importance of religion in adolescents’ lives
proved to be effective identifiers of those youth who failed
to meet expectations . . . in spite of being considered at
low risk to do so,” Regnerus said.
Big Babies: How Long Is Childhood?
Life may be going faster, but childhood seems to be slowing
down. So says the University of Chicago’s National
Opinion Research Center in a study designed by Penn’s
Network on Transitions to Adulthood. “Adulthood is
occurring much later than it did a few decades ago,” when
it was thought to happen at age 21, says network president Frank
Furstenberg, the Zellerbach Family Professor of
Sociology.
The voting age has dropped from 21 to 18, puberty is coming
earlier, and the
age at which citizens can be tried as adults has been lowered in most states.
But these numbers don’t tell the whole story, says Furstenberg. “Not
only do young people think these events should occur later, but everyone else
has shifted their standards as well.” The study’s criteria for
adulthood—completed education, full-time employment, financial independence,
marriage, children, and a few more—are all coming later in life, at around
26. “What’s mainly driving this is that
you cannot get a full-time job at 20 anymore,” he points out, not to
mention a discouraging rate of divorce. As childhood gets longer, “the
burden on the family is growing tremendously. Childbearing and child raising
are becoming more demanding. The family is assuming a heavy, heavy burden.”
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