News & Views in 1999

The first opening of the Bering Strait would have had profound biogeographical and climatic consequences. The date of that event is now firmly pushed further back in time.

The broad spectra of radioactive β-decay energies led to the discovery of the neutrino in the 1930s. There was also speculation that the shape of the spectrum could be used to measure a possible neutrino mass. In 1991, it was predicted that there should be ripples in the spectra called ‘β-environmental fine structure’ or BEFS. These ripples have been measured in a new experiment, which may eventually transcend the massive-neutrino controversy in that BEFS can be used to probe the atomic structure of many solids.

To survive in the wild it's important to be able to distinguish particular sounds from the background noise. But how do animals do this? A study of animal noises and their responses to them indicates that a phenomenon known as 'comodulation masking release' may be responsible for filtering naturally occurring sounds.

The first step in signalling through the transforming growth factor (TGF)-β pathway involves phosphorylation of either Smad2 or Smad3 by an activated type-I receptor kinase. How do TGF-β, the receptor and the Smad manage to meet up? The answer is a newly discovered ‘anchor’ protein termed SARA, which recruits the Smads to the TGF-β receptor.

To maintain the integrity of the genome, nuclear division (mitosis) must not occur if the DNA is damaged. To prevent this, Cdc25, an essential regulator of mitosis, is inactivated, and we now know how. DNA damage activates Chk1, which adds a phosphate group to Cdc25. This creates a binding site for Rad24, which then transports Cdc25 out of the nucleus where it cannot drive the cells into mitosis.

Daedalus suggests a solution to the radio noise from telecommunication satellite systems, and the problem they create for radioastronomers. For example, the 66 satellites of the Iridium system now entering service could collectively form a ‘very long baseline interferometer’ which could be made wonderfully directional — transmitting to and receiving from just few square metres around a specific ground station. Radiotelescopes elsewhere would detect nothing.

In genomic imprinting, one copy of a gene is switched off depending on whether it came from the father or mother. One explanation centres on the competing interests of the two parents. Another now brings in sex-associated differences in the offspring.

Contaminant transport in ground water is a contentious issue — especially when it comes to possible movement of radionuclides from nuclear test sites or storage facilities. Analyses carried out in Nevada now implicate colloids in the movement of plutonium from a nuclear detonation site. The case, however, has yet to be clinched, and the broader interest in this example lies in the questions it raises about identifying colloid-associated transport in general.

Many plants rely on herbivores to disperse their seeds. The plants present the seeds in a bright, tasty packaging, tempting herbivores to eat them. But what happens if the herbivore is then eaten by a predator? A study of fruit-eating lizards in the Canary Islands suggests that viable seeds can be ingested by the predator and taken on to new locations.

Plants have developed many mechanisms to fend off invaders, but the bugs are fighting back. In a series of reports, several groups describe how a viral protein, the helper component protease, is able to paralyse a plant defence mechanism that normally acts against viruses.

The life cycle of corals combines a dispersal, larval phase with a sedentary, adult phase. Larvae must find somewhere to settle down, and this process is termed recruitment. In the most comprehensive study yet, carried out on the Great Barrier Reef, one group has shown that recruitment rates vary substantially in various parts of the reef, and do not tally with adult abundances.

How strong is the bond formed between a protein and its ligand? Individual protein-ligand pairs can be pulled apart experimentally, and the force required to do so measured using atomic force microscopy. But, according to a new study, that's not the end of the story — the strength of the bond may also depend on how hard and fast you pull.

Because one of the enzymes that is needed to make chlorophyll requires light, a seedling that is grown in the dark (and is therefore etiolated) will have problems when it finally emerges into the sunshine — it will not have enough chlorophyll to protect it from the harmful effects of too much light. However, the enzyme that presents the plant with this dilemma, protochlorophyllide oxidoreductase, also gives it the solution.