M YSTERY SOLVED
Tail trouble for lizards
Salamanders and lizards can regrow their
tails but not to equal perfection.
While a regenerated salamander tail
closely mimics the original, bone and all, a
lizard’s replacement is filled with cartilage
and lacks nerve cells, or neurons. That
contrast is due to differences between
stem cells in the animals’ spinal cords,
researchers report online August 13 in the
Proceedings of the National Academy of
Sciences. When a salamander loses its tail,
its neural stem cells can develop into any
type of nervous system cell. But through
evolution, lizard neural stem cells “have
lost this ability,” says Thomas Lozito, a
biologist at the University of Pittsburgh.
Lozito and colleagues wondered if something about the biology of the lizard’s tail
was keeping its stem cells from becoming
neurons. So the team implanted neural
stem cells from an axolotl salamander
(Ambystoma mexicanum) into the tail
stumps of five mourning geckos (
Lepido-dactylus lugubris). Some of the salamander
cells became neurons in the regrown tails,
showing that the problem is with the lizard
stem cells. The finding suggests that scientists would have to alter only the lizard
stem cells, instead of other parts of the tail,
to regrow a more complete appendage.
Lozito is using lizards as “a stepping
stone” to one day coax stem cells in mammals to regenerate body parts.
Egyptian tomb held 3,200-year-old cheese
What may be the oldest known slab of solid cheese, dated to roughly 3,200 years
ago, has been found in an ancient Egyptian tomb.
Made from a mixture of cow milk and either sheep or goat milk, the cheese filled
Pregnant women’s use of opioids is on the rise
a broken clay jar unearthed from a 13th century B.C. tomb for Ptahmes, mayor of the
ancient city of Memphis, researchers report in the Aug. 21 Analytical Chemistry.
Chemist Enrico Greco and colleagues used mass spectrometry to analyze the
antique cheese — now a white, soapy lump weighing several hundred grams.
Besides milk and whey proteins, the cheese contains remnants of bacteria that
cause brucellosis infections, adding to evidence
that ancient Egyptians grappled with the dis-
ease, says Greco, who did the work while at the
University of Catania in Italy. Cheese making
predates the new find by more than 4,000 years
(SN: 1/26/13, p. 16). Archaeologists in 2014
reported finding 3,600-year-old curds draped
around the necks of Bronze Age mummies in
China. “There are other samples of dairy prod-
ucts in the literature, but not solid cheeses in
the strict sense,” Greco says. — Cassie Martin
The rate of opioid use among pregnant women more than quadrupled, from
1.5 to 6.5 per 1,000 women, from 1999 to 2014, according to records on hospital
deliveries in 27 states and the District of Columbia. That’s about 5,461 women versus 24,715 women, the U.S. Centers for Disease Control and Prevention reports in
the first study to look at opioid use in pregnant women by state. Vermont had the
highest rate in 2014: 48.6 per 1,000 women. Washington, D.C., had the lowest rate
at 0.7 per 1,000 women, CDC researchers report in the Aug. 10 Morbidity and
Mortality Weekly Report. Taking opioids during pregnancy, especially in the last
trimester, increases the risk of preterm birth, stillbirth and infant opioid withdrawal (SN: 6/10/17, p. 16). “This analysis is a stark reminder that the U.S. opioid
crisis is taking a tremendous toll on families,” says study coauthor and epidemiologist Jean Ko. — Leah Rosenbaum
This preserved solid cheese, found
in an ancient Egyptian tomb, shows
signs of contamination with bacteria
that cause the disease brucellosis.
No nerve In lizard and salamander tail cross
sections (left column), cartilage is shown as green
and a spinal cord with nerve cells is red. A lizard’s
regenerated tail (right column) is mostly cartilage,
but a salamander’s is cartilage and new nerve cells.
2006 2004 2008 20122014 2010
Rate of opioid use among U. S. pregnant women, 1999 to 2014
SOURCE: S.C. HAIGH T ET AL/ MM WR 2018