Can understanding squid life-history strategies and recruitment improve management?

Current views of the links between life-history strategies and recruitment processes in fish are contrasted with the pattern emerging for squid. A general perspective is that the roles of space and time are reversed inthe two groups, suggesting that management strategies also should differ. The space/time reversal appears to be more marked in the wide-ranging commercial ommastrephids than in the loliginids, which are morelocalized and have less extreme strategies. Fish have large energy reserves and efficient lifestyles, allowing stocks to produce numerous co-existing year-classes; as larvae surviving a wide range of potentially limiting conditions in different years, they store genetic diversity and stabilize recruitment in time. Squid are primarily annual species, so stocks can only achieve such diversity and stabilization by spawning microcohortsthroughout the year to disperse widely in space into equally variable microhabitats. This behaviour would link recruitment more tightly to environmental variability. The population dynamics and the tactics usedappear quite complex, possibly including kinship, school cohesion and cannibalism

The impact of environmental gradients on the early life inshore migration of the short-finned squid Illex illecebrosus

Recruitment of the short-finned squid Illex illecebrosus to adult feeding grounds on the shelf off eastern Canada constitutes an important transition from warm food-limited Gulf Stream waters to cold and productive slope and coastal waters. The impact of such gradients was addressed by analysing the gladius growth of 1585 juvenile squid collected across the Gulf Stream and shelf/slope fronts during research cruises conducted between 1979 and 1989. Temperature- and size-specific growth potential, as estimated by a bioenergetics model, were compared to measured gladius growth rates and revealed that young Illex were energetically expensive and food-limited in Gulf Stream waters (their hatching environment). Growth condition improved inshore, where metabolic costs decreased and more food became available. Similar patterns were observed when size-specific growth rates of squid caught across the temperature and food gradients were directly compared.In addition, transport processes in the Gulf Stream and slope water played an important role in providing access and retention in favourable areas. Juvenile onshore migration seems to be driven by elevated foodrequirements and involves physiological adaptations to compensate for decreasing temperatures. The individual “success” in terms of growth and survival may depend, however, on access to concentrated patches offood which, in turn, will be determined by timing and the transport dynamics of the main water masses

The importance of metagenomic surveys to microbial ecology: or why Darwin would have been a metagenomic scientist

Scientific discovery is incremental. The Merriam-Webster definition of 'Scientific Method' is "principles and procedures for the systematic pursuit of knowledge involving the recognition and formulation of a problem, the collection of data through observation and experiment, and the formulation and testing of hypotheses". Scientists are taught to be excellent observers, as observations create questions, which in turn generate hypotheses. After centuries of science we tend to assume that we have enough observations to drive science, and enable the small steps and giant leaps which lead to theories and subsequent testable hypotheses. One excellent example of this is Charles Darwin's Voyage of the Beagle, which was essentially an opportunistic survey of biodiversity. Today, obtaining funding for even small-scale surveys of life on Earth is difficult; but few argue the importance of the theory that was generated by Darwin from his observations made during this epic journey. However, these observations, even combined with the parallel work of Alfred Russell Wallace at around the same time have still not generated an indisputable 'law of biology'. The fact that evolution remains a 'theory', at least to the general public, suggests that surveys for new data need to be taken to a new level

The Enhancer of Trithorax and Polycomb Corto Interacts with Cyclin G in Drosophila

BACKGROUND: Polycomb (PcG) and trithorax (trxG) genes encode proteins involved in the maintenance of gene expression patterns, notably Hox genes, throughout development. PcG proteins are required for long-term gene repression whereas TrxG proteins are positive regulators that counteract PcG action. PcG and TrxG proteins form large complexes that bind chromatin at overlapping sites called Polycomb and Trithorax Response Elements (PRE/TRE). A third class of proteins, so-called "Enhancers of Trithorax and Polycomb" (ETP), interacts with either complexes, behaving sometimes as repressors and sometimes as activators. The role of ETP proteins is largely unknown. METHODOLOGY/PRINCIPAL FINDINGS: In a two-hybrid screen, we identified Cyclin G (CycG) as a partner of the Drosophila ETP Corto. Inactivation of CycG by RNA interference highlights its essential role during development. We show here that Corto and CycG directly interact and bind to each other in embryos and S2 cells. Moreover, CycG is targeted to polytene chromosomes where it co-localizes at multiple sites with Corto and with the PcG factor Polyhomeotic (PH). We observed that corto is involved in maintaining Abd-B repression outside its normal expression domain in embryos. This could be achieved by association between Corto and CycG since both proteins bind the regulatory element iab-7 PRE and the promoter of the Abd-B gene. CONCLUSIONS/SIGNIFICANCE: Our results suggest that CycG could regulate the activity of Corto at chromatin and thus be involved in changing Corto from an Enhancer of TrxG into an Enhancer of PcG