NEWS AND VIEWS mice have up to 30% fewer DRG neurons kinson's diseases, raising the possibility adult? The answer is probably that they and 30% of DRG neurons normally ex­ that failure of autocrine survival signalling act locally to regulate the survival and press TrkB, the subset of neurons that fail could contribute to degenerative neuro­ plasticity of axon terminals16,17. Consis­ to survive in the BDNF null mice might logical disease. Lastly, it will be of great tent with this view, anti-NGF antibodies normally depend on an autocrine BDNF interest to find out whether the types of prevent collateral sprouting but do not loop. Importantly, DRG neurons from adult neurons that are normally able to induce death of adult DRG neurons17. the BDNF null mice were used to confirm promote their own survival by an auto­ The relative importance of autocrine that the effect of the antisense oligo­ crine mechanism are better able to survive and target-derived survival signalling in nucleotides depended on the expression and regenerate their axons after injury. the nervous system may not become clear of BDNF and that the oligonucleotides The findings of Acheson et al. suggest a for some time, but some basic mechanistic were not nonspecifically toxic. Taken simple explanation as to why developing questions can be addressed in the near together, these results indicate that a sensory neurons switch from a target­ future. For instance, does the autocrine subset of adult sensory neurons can sus­ derived to an autocrine supply of survival Iigandlreceptor interaction require that tain their own survival in vitro, and prob­ factors. In accord with the neurotrophic the ligand is first secreted, or can it act ably also in vivo, by an autocrine loop. hypothesis, a competition for target­ intracellulariy? Can a cell regulate the They also suggest that survival signalling derived survival signals may initially help type of interactions that occur by pref­ continues to be essential for adult as well to match the numbers of neurons and· erentially sorting ligands or receptors to as developing cells14 . target cells. The survival of the winning specific cellular locations? And can elec­ What of other kinds of neurons? Auto­ neurons may then be stabilized in adult­ trical activity regulate the autocrine crine signalling may help to promote the hood by autocrine mechanisms to ensure 100p18? Whatever the answers, this much survival of some developing neurons prior their preservation for the lifetime of the is already clear: unlike good marks­ ll to target innervation ; furthermore, organism; glial cells, which develop for manship, understanding neuronal survival neurotrophins and their receptors are co­ the most part after target innervation, may sometimes require focusing away localized in a number of other types of may provide additional survival factors from the target. 0 neurons in the adult peripheral and cen­ (ref. 15; A. Meyer-Franke and B. Banes, tral nervous systems. As Acheson et al. unpublished observations). John V. Heymach Jr and Barbara A. Barres point out, these neuronal populations If adult sensory neurons do not need are in the Department of Neurobiology, include those involved in amyotrophic target-derived neurotrophic signals to Stanford University School of Medicine, lateral sclerosis, and Alzheimer's and Par- survive, what do such signals do in the Stanford, California 94305, USA. OBITUARY-----------------------------------------------------------------, William Alfred Fowler (1911-95) WILLIAM Alfred Fowler, who shared the paper which became familiarly known as 1960 the first steps of what became 1983 Nobel prize for physiCS, died on 14 B2FH. The paper showed how by nuclear known as nuclear chronology, a topic in March in Pasadena, California, at the age reactions in stars, occurring at increas­ which Fowler always remained active of 83. He received his undergraduate ing temperatures throughout stellar down the years. In 1964 came the theory education at Ohio State University, mov­ evolution, it was possible to build all of supernovae, with an attempt to com­ ing in 1936 as a graduate student to the bine the ideas on nucleosynthesis of California Institute of Technology, where B2FH with the astrophysical evolution of he spent the rest of his research career. supernovae up to the moment of their Fowler began his career by measuring explosion. In 1967, in collaboration with beta-ray spectra with the aim of deter­ R. V. Wagoner and myself, he devel­ mining the form of the weak nuclear oped what became known as Big Bang interaction, This led naturally, after the nucleosynthesis; and in 1975 he was end of the Second World War, to deter­ the senior author, in collaboration with mining experimental cross-sections for E. R. Caughlin and B. A. Zimmerman, of nuclear reactions of interest to astro­ another far-ranging work on thermo­ physics, a field in which for many years nuclear reactions in stars. This provided the Kellogg Radiation Laboratory at the basic information on nuclear reaction California Institute of Technology played rates that was encyclopaedic for almost a unique role. all reactions up to relative atomic mass In a monumental sequence of papers, about 25, an immense improvement on Fowler and his colleagues in the Kellogg what had been available at the com­ Radiation Laboratory provided the mencement of Fowler's work. essential experimental basis for the pro­ The technical description of a man's cesses known nowadays as hydrogen­ Willy Fowler, who died this month. career unfortunately says little of what he burning, the P-P chain (both these pro­ was really like. Known everywhere as cesses are catalytic cycles that convert the chemical elements starting from 'Willy', there can have been few scientists hydrogen to helium) and the carbon­ hydrogen, Broadly speaking, the lighter who have been so widely liked on the nitrogen cycle, work that was cited in the elements and the transition elements entire international stage. He will be Nobel prize award of later years. up to nickel were synthesized in charged greatly missed. From 1953 onwards, Fowler turned his particle reactions, and heavier elements, Willy Fowler is survived by his second attention increasingly to the great com­ from relative atomic mass about 60 wife, Mary Dutcher Fowler, and his two plex of nuclear reactions that charac­ upwards, in neutron reactions, although daughters by his first wife. Fred Hoyle terize the later stages of stellar evolution. nuclides of low natural abundance often Together with Geoffrey and Margaret departed from this simple model. He and Sir Fred Hoyle was formerly the Director of Burbidge and myself, he was co-author in I developed a number of spin-offs from the Institute of Theoretical Astronomy, 1957 of a seminal paper in this field, a B2FH in later years. These included in Cambridge, UK. 406 NATURE· VOL 374 . 30 MARCH 1995 .