Daily Archives: 20 April 2012

Friday Coffee Break

by Jeremy Yoder


Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

From Jon: Many kids diagnosed with attention-deficit hyperactivity disorder may be having trouble sleeping, instead.

“No one is saying A.D.H.D. does not exist, but there’s a strong feeling now that we need to rule out sleep issues first,” said Dr. Merrill Wise, a pediatric neurologist and sleep medicine specialist at the Methodist Healthcare Sleep Disorders Center in Memphis.

The symptoms of sleep deprivation in children resemble those of A.D.H.D. While adults experience sleep deprivation as drowsiness and sluggishness, sleepless children often become wired, moody and obstinate; they may have trouble focusing, sitting still and getting along with peers. [Links sic.]

From Sarah: Fencing off a Hawaiian peninsula to keep out non-native predators—including cats, dogs, and, yes, mongooses—is letting native birds and other species recover.

“The fence is doing its job,” said Eric VanderWerf, a biologist who, with his wife, Lindsay C. Young, is studying populations of albatrosses and shearwaters on a grant from the Packard Foundation. “The cats and mongooses were killing 15 percent of the chicks every year, and now they’re all gone.”

Each week, Dr. VanderWerf drives from Honolulu to check a system of 1,100 traps, cameras and poisoned-bait stations for any indication that a predator may have sneaked in. [Link sic.]

From Devin: A new review of computer simulation methods in ecology suggests it’s better to pair complex simulations with simpler mathematical models.
The increasing use of computer simulation by theoretical ecologists started a move away from models formulated at the population level towards individual-based models. However, many of the models studied at the individual level are not analysed mathematically and remain defined in terms of a computer algorithm. This is not surprising, given that they are intrinsically stochastic and require tools and techniques for their study that may be unfamiliar to ecologists. Here, we argue that the construction of ecological models at the individual level and their subsequent analysis is, in many cases, straightforward and leads to important insights.
And from Jeremy: biochemists have synthesized new DNA-like molecules, based on different structural components, that can store and replicate genetic information.

[Vitor] Pinheiro created his XNAs by tweaking a natural enzyme called DNA polymerase, which copies DNA. It ‘reads’ a piece of DNA, grabs nearby bases, and assembles a matching strand. If you set the polymerase loose upon its own gene, you can get the enzyme to make more copies of itself.

Here’s the clever bit. DNA polymerase is normally very fussy about the bases it grabs. It only selects ones with a deoxyribose sugar so that it assembles DNA, rather than any other nucleic acid. But Pinheiro evolved the enzyme so that it prefers to use the building blocks of his XNAs instead.