Some proteins keep “living fossil” pre-sequence

The sequences of hydrophobic segments of exported bacterial proteins, some serine proteinases and all known plastocyanins are examined in order to find out subsequences differing in amino acid composition and primary structure regularities. It is established that the extension in protein precursor, cleaved by a proteolysis (so-called P-sequence), demonstrates a higher share of usual amino acids (Thr, Pro, Ala, Ser, Arg, Gly, Leu, Val, Glu, Asp) and more clearly expressed periodicity compared to the mature protein (M-sequence). The obtained results confirm the conception of primitive proteins comprising a small number of amino acids realized a preferable bonding (between identical and very similar in structure-function-evolution sense).     

Does intra-individual major histocompatibility complex diversity keep a golden mean?

An adaptive immune response is usually initiated only if a major histocompatibility complex (MHC) molecule presents pathogen-derived peptides to T-cells. Every MHC molecule can present only peptides that match its peptide-binding groove. Thus, it seems advantageous for an individual to express many different MHC molecules to be able to resist many different pathogens. However, although MHC genes are the most polymorphic genes of vertebrates, each individual has only a very small subset of the diversity at the population level. This is an evolutionary paradox. We provide an overview of the current data on infection studies and mate-choice experiments and conclude that overall evidence suggests that intermediate intra-individual MHC diversity is optimal. Selective forces that may set an upper limit to intra-individual MHC diversity are discussed. An updated mathematical model based on recent findings on T-cell selection can predict the natural range of intra-individual MHC diversity. Thus, the aim of our review is to evaluate whether the number of MHC alleles usually present in individuals may be optimal to balance the advantages of presenting an increased range of peptides versus the disadvantages of an increased loss of T-cells.     

Can China's supply of scientific talent keep up with demand?

Opportunities for scientists abound as China sets its sights on joining the global biotech sector.     

Will phenotypic plasticity affecting flowering phenology keep pace with climate change?

Rising temperatures have begun to shift flowering time, but it is unclear whether phenotypic plasticity can accommodate projected temperature change for this century. Evaluating clines in phenological traits and the extent and variation in plasticity can provide key information on assessing risk of maladaptation and developing strategies to mitigate climate change. In this study, flower phenology was examined in 52 populations of big sagebrush (Artemisia tridentata) growing in three common gardens. Flowering date (anthesis) varied 91 days from late July to late November among gardens. Mixed‐effects modeling explained 79% of variation in flowering date, of which 46% could be assigned to plasticity and genetic variation in plasticity and 33% to genetics (conditional R² = 0.79, marginal R² = 0.33). Two environmental variables that explained the genetic variation were photoperiod and the onset of spring, the Julian date of accumulating degree‐days >5 °C reaching 100. The genetic variation was mapped for contemporary and future climates (decades 2060 and 2090), showing flower date change varies considerably across the landscape. Plasticity was estimated to accommodate, on average, a ±13‐day change in flowering date. However, the examination of genetic variation in plasticity suggests that the magnitude of plasticity could be affected by variation in the sensitivity to photoperiod and temperature. In a warmer common garden, lower‐latitude populations have greater plasticity (+16 days) compared to higher‐latitude populations (+10 days). Mapped climatypes of flowering date for contemporary and future climates illustrate the wide breadth of plasticity and large geographic overlap. Our research highlights the importance of integrating information on genetic variation, phenotypic plasticity and climatic niche modeling to evaluate plant responses and elucidate vulnerabilities to climate change.     

Is subarctic forest advance able to keep pace with climate change?

Recent climate warming and scenarios for further warming have led to expectations of rapid movement of ecological boundaries. Here we focus on the circumarctic forest–tundra ecotone (FTE), which represents an important bioclimatic zone with feedbacks from forest advance and corresponding tundra disappearance (up to 50% loss predicted this century) driving widespread ecological and climatic changes. We address FTE advance and climate history relations over the 20th century, using FTE response data from 151 sites across the circumarctic area and site‐specific climate data. Specifically, we investigate spatial uniformity of FTE advance, statistical associations with 20th century climate trends, and whether advance rates match climate change velocities (CCVs). Study sites diverged into four regions (Eastern Canada; Central and Western Canada and Alaska; Siberia; and Western Eurasia) based on their climate history, although all were characterized by similar qualitative patterns of behaviour (with about half of the sites showing advancing behaviour). The main associations between climate trend variables and behaviour indicate the importance of precipitation rather than temperature for both qualitative and quantitative behaviours, and the importance of non‐growing season as well as growing season months. Poleward latitudinal advance rates differed significantly among regions, being smallest in Eastern Canada (~10 m/year) and largest in Western Eurasia (~100 m/year). These rates were 1–2 orders of magnitude smaller than expected if vegetation distribution remained in equilibrium with climate. The many biotic and abiotic factors influencing FTE behaviour make poleward advance rates matching predicted 21st century CCVs (~10³–10⁴ m/year) unlikely. The lack of empirical evidence for swift forest relocation and the discrepancy between CCV and FTE response contradict equilibrium model‐based assumptions and warrant caution when assessing global‐change‐related biotic and abiotic implications, including land–atmosphere feedbacks and carbon sequestration.     

Slick science: will new BP funds keep Gulf genomics afloat?

Funding injections by British Petroleum this summer are fueling studies in the Gulf Coast, raising hopes that the Deepwater Horizon oil spill might provide answers to long-standing questions on the nature of cellular toxicity. Rebecca Alvania investigates.     

Can increased muscle ROS scavenging keep older animals young and metabolically fit?

Insulin resistance and lipid accumulation occur with aging, perhaps due to mitochondrial dysfunction. In this issue of Cell Metabolism (Lee et al., 2010), older mice overexpressing mitochondrial targeted catalase had reduced muscle mitochondrial oxidative damage, lower intramuscular lipid, and improved insulin sensitivity, suggesting that enhanced ROS scavenging prevents age-associated mitochondrial impairments and insulin resistance.     

Can macaroni penguins keep up with climate- and fishing-induced changes in krill?

Macaroni penguins have evolved to cope with the highly variable conditions of the Southern Ocean. However, changes in prey supply and patchiness potentially associated with changes in climate and krill fishing activity may be occurring too rapidly for the penguins to adapt. We use a stochastic dynamic programming model to examine how changes in both the mean and patchiness of krill supply may affect the foraging decisions, and therefore breeding success, of female macaroni penguins at South Georgia. We predict that rapid changes in the mean supply of prey will have more of an effect on the condition of the female and chick than changes in prey patchiness, and that changes in foraging behavior compensate for changes in prey up to a threshold point, beyond which breeding success is likely impacted. In particular, we predict that the location of the threshold is affected by whether or not the penguins are adapted to the prey environment in which they are foraging, with the female and chick receiving on average 20% less of their daily energetic requirement if the female is not foraging optimally.     

Is the secret for a successful aging to keep track of cancer pathways?

A successful aging could be gained by life satisfaction, social functioning, or psychological resources and, definitely, by increasing resistance to diverse age‐related pathologies. Nowadays, cancer can be considered an age‐related disease since the incidence of most cancers increases with age, rising more rapidly beginning in midlife. Although adults with extended longevity are less likely to develop cancer, it is now emerging that aging and cancer share common molecular links, and thus targeting these mechanisms may be suitable to treat multiple disorders, for the prolonging of healthy aging. At present, one of the cornerstones of antiaging is hormone‐replacement therapy to treat diseases associated with a state of age‐related sex‐hormone deficiency in women and men; however, many studies question the relationship of hormone replacement to cancer recurrence. Here, we discuss signaling and metabolic molecular crossroad linking aging and cancer. This is useful to argue about the current knowledge of prolongevity and druggable targets and to motivate specific intervention strategies that could modify practices of the aging population, activating multiple longevity pathways but keeping track of cancer pathways, thereby potentially preserving health status.     

Can mangroves keep pace with contemporary sea level rise? A global data review

Coastal vegetated wetlands such as mangrove forests provide multiple ecosystem services, though are potentially threatened by contemporary accelerated sea level rise (SLR), in addition to other immediate threats such as agriculture and coastal development. Several studies have revealed that mangroves are able to adapt to, and keep pace with local relative SLR through vertical surface elevation change (SEC), however data are lacking, with often only surface accretion rate (SAR) data available. We systematically review published studies of SEC and SAR from globally distributed monitoring sites using meta-analysis, and compare them with the Intergovernmental Panel on Climate Change Fifth Assessment Report (IPCC AR5) SLR scenarios. Hydro-geomorphic setting plays an important role, with basin mangroves potentially less vulnerable to SLR through land building processes. We find that SAR in both basin and fringe mangroves can cope with low SLR scenario (RCP 2.6) throughout the 100 years projection period. However, SAR can only keep pace with high SLR scenario (RCP 8.5) up to year 2070 and 2055 in basin and fringe mangrove settings respectively. These were associated with potential sediment accumulation of 41 cm and 29 cm respectively from the baseline. Mangrove degradation promoted lowering trends of SEC, while mangrove management such as rehabilitation practice stimulated positive trends of SEC. Mangrove ecosystems may be vulnerable to contemporary SLR in small island locations such as the Caribbean, East Africa and parts of the Indo-Pacific that are dominated by fringe mangroves and where SEC cannot keep pace with both low and high IPCC AR5 SLR scenarios. A global expansion of current mangrove surface elevation monitoring effort is urgently needed in order to better assess the vulnerability of mangroves, and the factors affecting their resiliency in the face of rising sea levels.     

Pores formed by Baxα5 relax to a smaller size and keep at equilibrium

Pores made by amphipathic cationic peptides (e.g., antimicrobials and fragments of pore-forming proteins) are typically studied by examining the kinetics of vesicle leakage after peptide addition or obtaining structural measurements in reconstituted peptide-lipid systems. In the first case, the pores have been considered transient phenomena that allow the relaxation of the peptide-membrane system. In the second, they correspond to equilibrium structures at minimum free energy. Here we reconcile both approaches by investigating the pore activity of the α5 fragment from the proapoptotic protein Bax (Baxα5) before and after equilibrium of peptide/vesicle complexes. Quenching assays on suspensions of large unilamellar vesicles suggest that in the presence of Baxα5, the vesicles maintain a leaky state for hours under equilibrium conditions. We proved and analyzed stable pores on single giant unilamellar vesicles (GUVs) in detail by monitoring the entrance of dyes added at different times after incubation with the peptide. When the GUVs came in contact with Baxα5, leakage started stochastically, was delayed for various periods of time, and in the majority of cases proceeded rapidly to completion. After hours in the presence of the peptide, the same individual GUVs that refilled completely at first instance maintained a porated state, which could be observed in subsequent leak-in events for serially added dyes. However, these long-term pores were smaller in size than the initial equilibration pores. Stable pores were also detected in GUVs made in the presence of Baxα5. The latter pores can be considered equilibrium states and may correspond to structures measured previously in bilayer stacks. Although pore formation may occur as a kinetic process, equilibrium pores may also be functionally relevant structures, especially in highly regulated systems such as the apoptotic mitochondrial pores induced by Bax.     

Colour learning in two behavioural contexts: how much can a butterfly keep in mind?

Here we examine the ability of butterflies to learn colour cues in two different behavioural contexts, nectar foraging and oviposition, more or less simultaneously. We first trained female Battus philenor (Papilionidae) butterflies to associate a given colour with the presence of host plant leaf extract and assayed their colour preference; we then trained a subset of these butterflies to associate a second colour with the presence of sucrose solution and assayed colour preference once more. When offered an array of four unscented and unrewarding coloured models, ‘single-trained’ butterflies consistently alighted most frequently on their oviposition training colour. Green-trained butterflies landed on nontrained colours only about 4% of the time, while butterflies trained to red, yellow or blue made about 23% of their landings on nontrained colours; of those nontrained landings, most were on green. The majority of ‘dual-trained’ butterflies made the greatest number of visits to both training colours in the appropriate behavioural context; that is, they probed the models of their sucrose-associated colour and alighted on the models of their oviposition-associated colour. Landings or probes on nontrained colours in one context were consistently biased towards what was learned in the alternative context, suggesting an information-processing constraint in the butterflies. This paper provides a clear demonstration that butterflies can learn in two behavioural contexts within a short span of time. A capacity for such dual conditioning presumably permits female butterflies to forage effectively for egg-laying sites and nectar resources even when those activities are intermingled in time. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.       

Insect diversity of a Costa Rican dry forest: why keep it,and how?

The dry forest of the 108 km2 Santa Rosa National Park in northwestern Costa Rica contains as many as 13 000 species of insects (including 3140 species of moths and butterflies) sustained by and sustaining about 700 species of plants and 400 species of vertebrates. These insects require explicit conservation attention. They are more than just decorations on the plants; rather, they are the building blocks and glue for much of the habitat. They are the food for much of the carnivore community, and the insect species are not merely interchangeable bits of nutrients. They are major killers of seeds, and thereby influence both the plant species composition of a habitat and prevent the better competitors from taking it over. They are the primary pollinators and are specific enough to be neither interchangeable nor replaceable with other animals; the seeds resulting from their pollination activities are major animal foods in the habitat. They are a diverse, puzzling, complex, intrinsically attractive, and major part of the intellectual display offered by tropical wildlands, the display that will be the eventual foundation for most of the reason why tropical wildlands will be retained as such in the future.
The retention and maintenance of insect species richness in a tropical wildland is strongly rooted in the preservation of plant species richness, in maintaining habitat mosaics (different members of which are used by a given insect in different seasons), in preserving a large diversity of habitats, and in recognizing the threat posed by insect crop associates in nearby agricultural lands.     

Cyclism revisited: extinction and ‘Achilles’ Heels' keep diversification in check on macroevolutionary time scales

Mass extinctions of varying magnitude prune the continuous diversification predicted by Darwinian evolutionary processes. They are caused by events that are too rare to become adaptatively accommodated. Their effects depend not only on the nature and magnitude of the triggering event but also on the state of the biosphere at the particular time. This is most clearly shown by the existence of Golden Ages preceding all Phanerozoic mass extinctions. These coincide with greenhouse periods, in which doomed clades gave rise to heteromorphs, deviating in strange ways from established bauplans. When critically examined, the seemingly ‘decadent’ morphologies of Schindewolf's ‘typolytic stages’ turn out to have been highly functional. The paradoxical link between adaptive peaks and evolutionary failure can now be explained. Specialisation tends to increase vulnerability (1) by narrowing niches and (2) by the retention of clade-specific conservative features that happen to become fatal Achilles’ Heels for entire clades in the face of a particular perturbation. Following extinctions, the availability of open niches favoured relatively rapid diversification of more innovative clades and their rise to ecological dominance (Schindewolf's ‘typogenetic stage’). Although the long-term changes can be observed only in the fossil record, Golden Biotopes in the present biosphere show that the Darwinian process may also be promoted by ecological isolation. As a result, clade histories do resemble individual biographies, but for ecological rather than orthogenetic reasons. This insight may help us to deal with the present mass extinction caused by our own species.     

Into the world of steroids: A biochemical “keep in touch” in plants and animals

Evolution of steroids such as sex hormones and ecdysteroids occurred independently in the animal and plant kingdoms. Plants use phytoecdysteroids (PEs) to control defense interactions with some predators; furthermore, PEs can exert beneficial influence on many aspects of mammalian metabolism. Endocrine disrupting compounds such as the estrogen agonist bisphenol A (BPA) are widespread in the environment, posing a potential hormonal risk to animals and plants. Adverse BPA effects on reproductive development and function are coupled with other toxic effects. BPA bioremediation techniques could be developed by exploiting some tolerant plant species.Key words: androgens, endocrine disrupting compounds, bisphenol A, estrogens, hormone receptors, phytoecdysteroids