Commentary on Baverstock; the gene; an appraisal.

I argue that Baverstock's demotion of the gene in favour of the cellular phenotype is still too limited, and that phenotypes must be considered at multiple irreducible levels. I emphasise process thinking and the significance of agency in living systems.

Temporal effects of dehydroepiandrosterone sulfate on memory formation in day-old chicks.

Dehydroepiandrosterone sulfate (DHEAS) has been shown to enhance memory retention in different animal models and in various learning paradigms. In the present study, we investigated the effect of peripherally administered DHEAS on the acquisition, consolidation and retention of memory using a weak version of the one-trial passive avoidance task in day-old chicks. Intraperitoneally administered DHEAS (20 mg/kg) either 30 min before or 30 min and 4.5 h after training on the weakly aversive stimulus, enhanced recall at 24 h following training, suggesting a potentiation of not only the acquisition but also the early and late phases of memory consolidation. In contrast, when DHEAS was administered at 30 min prior to the 24 h retention test there was no memory enhancement, indicating a lack of effect on memory retrieval. Memory recall was unaltered when DHEAS was administered at 30 min before training in a control group trained on a strongly aversive stimulus, confirming memory-specific effects. Interestingly, the memory enhancement appeared to be sex-specific as male chicks showed higher recall than females. These findings provide further evidence that DHEAS enhances memory and may be involved in the temporal cascade of long-term memory formation.

The peptide sequence Arg-Glu-Arg, present in the amyloid precursor protein, protects against memory loss caused by A beta and acts as a cognitive enhancer.

Amino acid sequences containing the palindromic tripeptide RER, matching amino acids 328-330 of the amyloid precursor protein APP, when injected intracerebrally prior to or just after training, protect against memory loss induced by amyloid-beta (A beta) in a one-trial passive avoidance task in the young chick. RER also acts as a cognitive enhancer, strengthening memory for a weak version of the task. N-terminal acylation of RER protects it against rapid degradation, and AcRER is effective in restoring memory if administered peripherally. Biotinylated RER binds to chick neuronal perikarya in an APP-displaceable manner via 66 and approximately 110 kDa neuronal cell membrane proteins. We suggest that RER binding is likely to exert effects on memory retention via receptor-mediated events that include activation of second messenger pathways. These findings suggest that RER and its derivatives may offer a novel approach to enhancing the neuroprotective effects of APP and alleviating the effects of memory loss in the early stages of Alzheimer's disease.

How to (or not to) communicate science.

Protagonists for 'the public understanding of science' still sometimes fail to recognize that there is also a need for 'the scientists' understanding of the public' and that for most of science most of the time we are all public. 'Science' is communicated to 'the public' through popular books, museums, TV, the Internet, but far too often the present state of scientific belief is presented uncritically as the onward march of truth as discovered by Euro-American males. This has contributed to a widespread public concern, if not mistrust, in many areas of science, not least genetics and neuroscience. Although researchers often criticize the media for misrepresenting their work, the hype and simplifications often begin with the press releases put out by the researchers, their institutions and the scientific journals themselves. I conclude by looking more optimistically at the ways in which, by bringing natural science into theatre, novels and other art forms, the fragmentation of our culture may be diminished.

Communication: from neurons to people; from present to future.

From its emergence out of organic chemistry and physiology a century ago, the history of biochemistry is one of shifting research agendas. For organic chemists, the questions were those of structure and composition, while for physiologists, they were questions of function. The dynamic biochemistry of the mid-20th century centred on catalysis, energy flow and metabolism. The emergence of molecular biology ('practising biochemistry without a licence') introduced information in place of energy as an organizing cellular principle, but in doing so forgot dynamics. For Crick's Central Dogma, information -- signals -- flowed in one direction only. Now, proteomics is enabling molecular biologists to rediscover biochemistry once more. Signalling -- the processes of communication across space and time -- occurs at all biological levels. I will review them, and their potential future. Will the metaphor of signalling provide a new organizing principle, one that recognizes the essentially interactive nature of information flow within metabolic webs?: I discuss first, the conservation of signalling molecules at the cellular level over evolutionary time; secondly, the supracellular level of physiological signalling in multicellular organisms -- hormones and neurons; thirdly, supraorganismic signalling and communication -- from pheromones to speech; and finally, signalling and reception within and outside the biochemical community - how do we/can we communicate with one another and the rest of the world?

Dehydroepiandosterone and its sulphate enhance memory retention in day-old chicks.

We report the presence of dehydroepiandosterone (DHEA) and DHEA sulphate (DHEA-S) in the day-old-chick brain, and their possible role in memory formation. DHEA and DHEA-S were present in the brain at higher concentrations than in the plasma. Radioimmunoassay examination of the intermediate medial hyperstriatum ventrale 5 or 30 min after training or the lobus parolfactorius 60 or 120 min after training on the passive avoidance task did not show learning-related differences in absolute levels of DHEA or DHEA-S. However, bilateral intracerebral injections of DHEA or DHEA-S before or after training on the weak passive avoidance task enhanced recall 24 h after training. Memory retention was enhanced by administration of DHEA and DHEA-S 15 min before training or 30 and 60 but not 180 min after training. Neurosteroids are present in high concentrations in regions of the chick brain known to be associated with learning and memory for an aversive one-trial task. Our study demonstrates that memory retention for this task is enhanced by administration of the neurosteroids DHEA-S and DHEA. These findings provide additional evidence that these neurosteroids have memory-enhancing properties and, thus, if common to other tasks and species, that DHEA-S and DHEA may constitute potential therapeutic tools for the treatment of cognitive deficits.