News & Views in 1999

How do growing axons in the central nervous system navigate through the jungle of cells that they encounteren routeto their targets? They are influenced by attractive and repulsive factors. One such factor, known as Derailed, is now shown to cause axon growth cones to head towards the so-called anterior commissure. It does so by repelling those axons that contain it from the posterior commissure.

The cochlea, found deep in the inner ear, detects sounds using an elaborately tuned basilar membrane. This membrane divides the cochlea lengthways into two fluid-filled compartments. To find out how fluid dynamics in these compartments affect hearing, scientists would like to measure the fluid flow and, although technically difficult, this has finally been done.

The formation of crust at mid-ocean ridges is generally thought to involve the ascent and melting of mantle rocks, which erupt as basalt magmas and create crust. But evidence from an ophiolite — a ridge fragment preserved on land — points to the existence of a different process. It involves incursion of sea water into the top of the mantle, and repetitive melting of rocks to create andesite magma.

The ability of a growing fetus to accept foreign tissue as part of itself could be exploited to create mixed species. The most challenging mixture would be an animal-plant hybrid, which would allow ‘little green men’ to photosynthesize once the problem of a common sap and blood supply is solved.

Flowering plants are comparative newcomers in evolutionary terms, but identifying their origins and the relationships between the 250,000 or so living species remains one of evolutionary biology's big questions. Two studies have taken the approach of multigene analysis to map out the deepest branches of the flowering-plant evolutionary tree.

As genome sequences become more widely available we need to be able to translate the information into protein function. Traditional approaches involve working out the functions of small groups of proteins involved in specific biological processes. But a new approach has been developed in the budding yeastSaccharomyces cerevisiae, to generate thousands of mutants and then screen them for function.

A long-standing ecological puzzle is why plant communities don't consist of a single competitively dominant species. A new model shows that plankton diversity can be maintained by the population dynamics that result from species competing for resources.

Charley Steinberg: A self-effacing influence in genetics and immunology, said by Richard Feynman to be the smartest guy he had ever met.

Some quantum states are hard to create and maintain, but are a valuable resource for computing. Twenty-first century entrepreneurs could make a fortune selling disposable quantum states.

Clouds of hydrogen gas moving at unusually high velocities have long puzzled astronomers, who have proposed two competing theories to explain their origins. New measurements showing surprisingly different compositions for two nearby clouds are likely to increase the debate rather than lessen it.

The precursor of the gas dimethylsulphide (DMS) is produced by phytoplankton. Oceanic emissions of this compound put sulphur into the atmosphere, where it is thought to exert a cooling effect on climate. A new study shows that the depth of surface-layer ocean mixing, which itself depends on climatic factors such as wind and temperature, seems to be a determinant of the level of DMS production.

As techniques to sequence and map genomes and chromosomes improve, we should be able to learn more about our evolutionary history and what the genomes of our ancestors might have looked like. Three studies illustrate the potential of these approaches, comparing the genomes of 15 primate species with those of species from four non-primate orders to try and work out which are the ancestral mammalian genes.

Organ transplantation remains a difficult procedure that is especially dogged by the problem of immunological rejection. Daedalus plans to circumvent this hurdle by injecting large cohorts of fetuses with each others' cells, so making their organs compatible in adult life and revolutionizing transplant procedures.

All known methods to increase lifespan come at a price. Usually, the costs are problems in development and fertility. But mutant mice have now been generated that live almost one-third longer than normal yet with no apparent side effects. These mice contain mutations in the gene that encodes a protein called p66^shc, which is thought to be involved in the response to oxidative DNA damage.

Evidence for tectonic activity under the ocean comes from molten rocks that erupt at mid-ocean ridges. Chemical differences between volcanic rocks found at the ridge and nearby support a passive model of mantle flow whereby magma rises to the surface in response to the plates moving apart.

The ATP synthase enzyme catalyses the production of ATP from ADP and inorganic phosphate. It does so using a clever internal rotary mechanism, the latest insight into which is now reported. Using sophisticated NMR and chemical probes, one group has uncovered structural changes in a critical subunit that could drive the rotation.

Microporous materials can now be designed from first principles. A new metal-organic framework has a crystalline structure that is twice as porous as most zeolites, which are currently the catalysts of choice for many industrial processes and domestic water softeners.

Guido Pontecorvo: Founder of modern genetics, who studied the structure and organization of genes.