News & Views in 1999

From remote measurements taken by an aircraft over the Arctic, it seems that bromine (chemical species of which destroy ozone) may occur in significant amounts in the troposphere there. It is thought that natural processes at the sea- or ice-surface create the bromine in molecular form, and the authors propose a mechanism whereby it is lofted into the troposphere. How important tropospheric bromine might be globally remains to be seen.

The number of harmful mutations that arise in each generation has been measured, and it is surprisingly high. This supports one theory of why evolution favours sexual reproduction, but the consequences for human health are unclear.

A new type of organic solid-state laser is promised by research into zeolitic microcrystals. By trapping individual organic dye molecules in the nanometre cavities of the zeolite, researchers have been able to produce microlasers only 8 μm in diameter. Such tiny lasers could be used as bright pixels for displays or in optical sensing and communication.

New measurements of polarized radio emission from a barred spiral galaxy have allowed researchers to determine the galactic magnetic field, and to link it to interstellar gas flow in the bar region. Their results suggest that magnetic stress may be an efficient way of fuelling the supermassive black hole thought to exist in the active galactic nucleus of many galaxies.

For a year now, marine biologists have been gathering data from a new satellite-borne sensor that delivers information on the distribution and abundance of phytoplankton in the world's oceans. The instrument is known as the Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS), and in December last year oceanographers met to take stock of the results it has provided.

Exploration of the 'brain pan', a layer of cultured brain cells in a petri dish, is this week taken further. Daedalus reckons he has now invented the ultimate neural net computer, which can be educated, and in more sophisticated forms equipped with sound and vision inputs, and hydraulic outputs.

During development, some neurons can change their sensitivity to neurotransmitters such as GABA. At birth, these neurons contain high concentrations of Cl⁻ ions, which means that GABA excites them. But just a week after birth, they contain much less intracellular Cl⁻, and GABA is inhibitory. The protein responsible for this switch has now been identified, and is shown to be a K⁺/Cl⁻co-transporter called KCC2.

Seismic tomography, a technique for imaging Earth's deep interior, is becoming ever more refined. The latest work tracks the subduction of a lithospheric slab below Siberia down to 2,800 km beneath the Earth's surface and back to Jurassic times.

The giant white clams of Sagami Bay, Japan, live at depths of more than 1,100 metres. Their spawning has been recorded on video and, remarkably, has been subject to experiment, which seems to show that the timing of spawning is controlled by slight increases in water temperature.

A cell's response to stress is often linked to protein synthesis and folding. These responses must have been conserved through evolution — otherwise, how would multicellular organisms ever have arisen? An evolutionary link has now been found in the form of a newly cloned mammalian stress-response protein called PERK. This protein has features of two gene products that are involved in the stress response in yeast.

Three recent papers have demonstrated the existence of ‘ferroelectric’ ice, in which some of the dipolar water molecules are aligned. The evidence came from experiments with normal ice, either grown on a substrate or doped with impurities, and although it resolves the debate about whether such ice exists, it reopens the thermodynamic question of whether nature prefers order at low temperatures.

Telomeres, the ends of chromosomes, present cells with a problem -- they can trigger DNA-damage responses and may become degraded or fuse with one another. To prevent this, telomeres are complexed with proteins. One such protein -- the Oxytricha telomere end-binding protein -- has now been crystallized, and the structure shows how it is exquisitely tailored for its job.

Hydrogenases are bacterial enzymes that catalyse the production or consumption of hydrogen. They come in two forms, one of which — iron-only hydrogenase -- has defied structure determination until now. Two groups however have cracked the problem and have produced structures of the enzyme from two different bacteria.

When taking a long journey, you may use a train to cover most of the distance then a bus to complete the trip. In the same way, vesicles may be carried around the cell mainly by microtubules, then finish their journey on actin filaments. For the first time, these two processes are shown to link directly by the interaction of a kinesin motor with a myosin motor.

Physicists have actively manipulated the shape of a quantum wavefunction, demonstrating an unprecedented amount of control over the quantum state. In an experiment last year, researchers used a variant of quantum holography to measure the wavefunction of an atomic electron. Now they have applied this technique to produce any desired wavefunction of the atomic electron via a feedback loop.

The social instincts of a colourful coral reef fish, known as the Moorish idol, are the subject of a posthumous paper by Konrad Lorenz. It describes Lorenz's observations between 1976 and 1978 of how Moorish idols develop from typical antisocial teenagers into fully integrated members of aquarium society.

Mouse brain cells can grow and divide in vitro. This prompts Daedalus to suggest that the hit-and-miss business of psychoactive drug design could be transformed by experiments on cultured brain cells in a petri dish. That would reduce the need for tests on animals and humans.

Neurophysiologist