Fish cognition: what can we learn, and what do they need to learn?

Fish provide a wonderful opportunity to explore processes that shape and select cognitive ability. In this presentation, I will illustrate three aspects of work that my colleagues and I have used to investigate fish learning and memory over the last decade. First, I will discuss how comparing different populations sampled from contrasting habitats allows differences in cognitive ability to be related to the evolutionary ecology of the fish. I will use examples that have investigated how differences in learning ability between populations of the same species can arise. Here, the examples will be taken from the ubiquitous three‐spined stickleback, and a Panamanian poecilid, Brachyraphis .
The second approach has used fish cognition as a tool to quantify behaviour to enable assessment of different aspects of fish welfare. For example, the recent work investigating pain perception in trout required the use of a learning task to quantify how fish behaviour was modified after noxious stimulation. Ways in which these, and similar, processes can be used in future studies of fish welfare will be discussed.
The final part of the presentation will consider recent work that addresses the problems of releasing hatchery‐reared fish for restocking purposes. Although a common practice, most of the hatchery‐reared fish die shortly after they are released. Much of the observed mortality apparently stems from the fishes' inexperience with a variable environment. Experiments with juvenile cod and brown trout suggest that both age, and the early rearing environment, have profound effects on fish learning and behaviour. I will discuss how simple modifications to current rearing practices may have large beneficial effects on the post‐release survival of hatchery‐reared fish.     

Archaea: what can we learn from their sequences?

Gene-by-gene and traditional biochemical approaches continue to reveal surprising molecular features in the archaeal domain. In addition, the complete sequencing of several archaeal genomes has further confirmed the phenotypic coherence of these micro-organisms at the molecular level. Nevertheless, the phylogeny of Archaea and the nature of the last universal common ancestor are still matters for debate.     

Malaria in pregnancy and the endemicity spectrum: what can we learn?

The increased susceptibility of pregnant women to malaria infection has long been recognized, but the magnitude of the disease burden in this particular group, together with the pathophysiology of maternal malaria and the specific difficulties in treatment, have only recently been the focus of research. Most research on maternal malaria has derived from sub-Saharan Africa where transmission is high, whereas most of the studies on the treatment of malaria and the effect of non-falciparum species has been conducted in low-transmission areas of Asia. In this paper, we attempt to improve our understanding of the disease and its mechanisms from observed differences and similarities between contrasting areas of transmission, and to identify priorities for future research.     

Phylloquinone, what can we learn from plants?

The plant plasma membrane contains redox proteins able to mediate a trans-membrane electron flow. This electron flow might be responsible for the generation of the active oxygen species observed as a reaction to pathogen attack or stress. Vitamin K1 could be identified as a possible lipid soluble electron carrier in plant plasma membrane preparations. Such a function would be analogous to coenzyme Q in animal plasma membranes. What we are going to outline in this contribution is a concept of how the electron transport system of the plant plasma membrane could interact with quinones, thus contributing to the metabolism of free radicals in plants.     

Spatial pattern in Antarctica: what can we learn from Antarctic bacterial isolates?

A range of small- to moderate-scale studies of patterns in bacterial biodiversity have been conducted in Antarctica over the last two decades, most suggesting strong correlations between the described bacterial communities and elements of local environmental heterogeneity. However, very few of these studies have advanced interpretations in terms of spatially associated patterns, despite increasing evidence of patterns in bacterial biogeography globally. This is likely to be a consequence of restricted sampling coverage, with most studies to date focusing only on a few localities within a specific Antarctic region. Clearly, there is now a need for synthesis over a much larger spatial to consolidate the available data. In this study, we collated Antarctic bacterial culture identities based on the 16S rRNA gene information available in the literature and the GenBank database (n > 2,000 sequences). In contrast to some recent evidence for a distinct Antarctic microbiome, our phylogenetic comparisons show that a majority (~75 %) of Antarctic bacterial isolates were highly similar (≥99 % sequence similarity) to those retrieved from tropical and temperate regions, suggesting widespread distribution of eurythermal mesophiles in Antarctic environments. However, across different Antarctic regions, the dominant bacterial genera exhibit some spatially distinct diversity patterns analogous to those recently proposed for Antarctic terrestrial macroorganisms. Taken together, our results highlight the threat of cross-regional homogenisation in Antarctic biodiversity, and the imperative to include microbiota within the framework of biosecurity measures for Antarctica.     

Understanding variation in human fertility: what can we learn from evolutionary demography?

Decades of research on human fertility has presented a clear picture of how fertility varies, including its dramatic decline over the last two centuries in most parts of the world. Why fertility varies, both between and within populations, is not nearly so well understood. Fertility is a complex phenomenon, partly physiologically and partly behaviourally determined, thus an interdisciplinary approach is required to understand it. Evolutionary demographers have focused on human fertility since the 1980s. The first wave of evolutionary demographic research made major theoretical and empirical advances, investigating variation in fertility primarily in terms of fitness maximization. Research focused particularly on variation within high-fertility populations and small-scale subsistence societies and also yielded a number of hypotheses for why fitness maximization seems to break down as fertility declines during the demographic transition. A second wave of evolutionary demography research on fertility is now underway, paying much more attention to the cultural and psychological mechanisms underpinning fertility. It is also engaging with the complex, multi-causal nature of fertility variation, and with understanding fertility in complex modern and transitioning societies. Here, we summarize the history of evolutionary demographic work on human fertility, describe the current state of the field, and suggest future directions.     

Cellulose: To depolymerize… or not to?

Oxidation of the primary OH groups in cellulose is a pivotal reaction both at lab and industrial scale, leading to the value-added products, i.e. oxidized cellulose which have tremendous applications in medicine, pharmacy and hi-tech industry. Moreover, the introduction of carboxyl moieties creates prerequisites for further cellulose functionalization through covalent attachment or electrostatic interactions, being an essential achievement designed to boost the area of cellulose-based nanomaterials fabrication. Various methods for the cellulose oxidation have been developed in the course of time, aiming the selective conversion of the OH groups. These methods use: nitrogen dioxide in chloroform, alkali metal nitrites and nitrates, strong acids alone or in combination with permanganates or sodium nitrite, ozone, and sodium periodate or lead (IV) tetraacetate. In the case of the last two reagents, cellulose dialdehydes derivatives are formed, which are further oxidized by sodium chlorite or hydrogen peroxide to form dicarboxyl groups. A major improvement in the cellulose oxidation was represented by the introduction of the stable nitroxyl radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). However, a major impediment for the researchers working in this area is related with the severe depolymerisation occurred during the TEMPO-mediated conversion of CH₂OH into COOH groups. On the other hand, the cellulose depolymerisation represent the key step, in the general effort of searching for alternative strategies to develop new renewable, carbon-neutral energy sources. In this connection, exploiting the biomass feed stocks to produce biofuel and other low molecular organic compounds, involves a high amount of research to improve the overall reaction conditions, limit the energy consumption, and to use benign reagents. This work is therefore focused on the parallelism between these two apparently antagonist processes involving cellulose, building a necessary bridge between them, thinking how the reported drawbacks of the TEMPO-mediated oxidation of cellulose are heading towards to the biomass valorisation, presenting why the apparently undesired side reactions could be turned into beneficial processes if they are correlated with the existing achievements of particular significance in the field of cellulose conversion into small organic compounds, aiming the general goal of pursuing for alternatives to replace the petroleum-based products in human life.     

What can we learn by studying enzymes in non-aqueous media?

What is the role of water in enzyme structure and function? One approach to answers should come from studies in which the amount of water present is a variable. In the absence of bulk liquid water, effective monitoring of enzyme action requires an alternative fluid medium through which substrates and products may be transported. The past 20 years have seen quite extensive study of enzyme behaviour when reactants are transferred via a bulk phase that is an organic liquid, a supercritical fluid or a gas. Some lipases, at least, remain highly active with only a few, if any, residual water molecules. Many enzymes seem to require larger amounts of water, but still not a liquid water phase. There are hysteresis effects on both the amount of bound water and the observed catalytic activity. Increasing hydration promotes mobility of the enzyme molecule, as revealed by various techniques, and there are correlations with catalytic activity. There are other plausible roles for hydration, such as opening up proton conduction pathways.     

To model or not to model?

In theory, the combination of mathematical modeling with experimental studies can be a powerful and compelling approach to understanding cell biology. In practice, choosing appropriate problems, identifying willing and able collaborators, and publishing the resulting research can be remarkably challenging. To provide perspective on the question of whether and when to combine modeling and experiments, a panel of experts at the 2010 ASCB Annual Meeting shared their personal experiences and advice on how to use modeling effectively.     

To charge or not to charge?

The ability to engineer proteins with increased thermostability will profoundly broaden their practical applications. Recent experimental results show that optimization of charge-charge interactions on the surface of proteins can be a useful strategy in the design of thermostable enzymes. Results also indicate a possibility that such optimized interactions provide structural determinants for enhanced stability of proteins from thermophilic organisms. In this article, the general strategy for design of thermostable proteins and perspectives for future studies are discussed.