Snippets Jan 16

This worm lost a quarter of its DNA

Inspecting the tiny roundworms Caenorhabditis briggsae (C briggsae) and Caenorhabditis nigoni (C nigoni) through a microscope, you'd have trouble telling them apart. Both are about a millimetre long and transparent. The key distinction between the two nematodes is their sex lives. Sex in C nigoni takes place between a male and a female. But only a small minority of C briggsae are males. The rest are hermaphroditic females that reproduce by self-fertilising or selfing. This sexual switch may have caused profound changes at the genetic level for C briggsae. In a study published in the journal Science, biologists reported that C briggsae lost thousands of genes - a staggering quarter of its genome - since it diverged from C nigoni a million years ago.

In their study, the biologists compared C briggsae and C nigoni, and discovered that C briggsae has about 7,000 fewer genes. Digging into a specific example of what C briggsae lost when it dumped all those genes, the researchers studied male secreted short genes, which have been found in all studied Caenorhabditis species except those with selfing hermaphrodites.

4D physics in two dimensions

For the first time, physicists have built a 2D experimental system that allows them to study the physical properties of materials that were theorised to exist only in 4D space. A team of researchers from USA, Switzerland and Israel have demonstrated that the behaviour of particles of light can be made to match predictions about the 4D version of the 'quantum Hall effect' in a 2D array of 'waveguides'.

A paper describing the research appeared in the journal  Nature  along with a paper from a separate group from Germany that has shown that a similar mechanism can be used to make a gas of ultracold atoms exhibit 4D quantum Hall physics as well.

When Will Humans Live on Mars?

Up until very recently, space travel and exploration has been an activity that only government-funded mega-ventures have been capable of taking part in. Advancements in aeronautics and space engineering have opened the door for private companies to enter this arena, and VICE spinoff Motherboard's documentary When Will Humans Live on Mars? profiles some of the leading companies working to make space more accessible. As has often been the case throughout history, the drive to make a buck is the primary intent of what the filmmakers coin 'Space 2.0'. It also offers insights into the growing space tourism industry. To watch, visit

The key molecule in cell fate regulation

One of the most important steps for understanding our brains is the regulation of the development of neurons and glial cells from a common progenitor neural cell. Unlocking the specifics of this 'neuron–glial cell-fate switch' is perhaps crucial to understanding how a functional nervous system is built.

In this light, researchers from India and Belgium have discovered a key molecule called Dmrt5 involved in this cell fate regulation. While studying the mouse's hippocampus, scientists had previously shown the role of another molecule - Lhx2 - in this decision. They had demonstrated that higher levels of Lhx2 promoted the production of neurons and suppressed the production of glial cells in the mouse's brain, whereas lower levels of Lhx2 had the opposite effect.

Now, they have shown that Dmrt5 can also mimic Lhx2 to produce the same effects of increasing production of neurons and suppressing the production of glial cells. They also observed that both Lhx2 and Dmrt5 were seen to compensate for each other's loss in the mouse's hippocampus. The findings could be an important step towards unravelling the neuron-glial cell-fate switch.

Odd directional preference

Scientists analysing results of spinning protons striking different sized atomic nuclei at the Relativistic Heavy Ion Collider (RHIC) found an odd directional preference in the production of neutrons.

Imagine playing a game of billiards, putting a bit of counter-clockwise spin on the cue ball and watching it deflect to the right as it strikes its target ball. Now imagine your counter-clockwise spinning cue ball striking a bowling ball instead, and deflecting more strongly - but to the left - when it strikes the larger mass.

This what the scientists noticed when analysing results of spinning protons striking different sized atomic nuclei. Neutrons produced when a spinning proton collides with another proton come out with a slight rightward-skew preference. But when the spinning proton collides with a larger nucleus, the neutrons' direction switches to the left.

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