Specificity of a milk clotting enzyme extracted from the thistleCynara cardunculus L.: Action on oxidised insulin and k-casein

Summary K-casein and oxidised insulin were digested with an acid protease extracted fromCynara cardunculus L. The fragments produced were isolated and characterised. In k-casein cleavage occured specifically at Phe 105-Met 106 bond. In oxidised insulin seven fragments were obtained and cleavage was found to occur at the carboxylic side of (Phe, Leu, He)-X, where X was preferentially Val or Tyr. The results obtained with insulin B chain suggest thatCynara cardunculus L. protease possesses a greater specificity than other acid proteases reported.     

Mapping the Polarity Interactome

Interactions between proteins are an essential part of biology, and the desire to identify these interactions has led to the development of numerous technologies to systematically map protein–protein interactions at a large scale. As in most cellular processes, protein interactions are central to the control of cell polarity, and a full understanding of polarity will require comprehensive knowledge of the protein interactions involved. At its core, cell polarity is established through carefully regulated mutually inhibitory interactions between several groups of cortical proteins. While several interactions have been identified, the dynamics and molecular mechanisms that control these interactions are not well understood. Cell polarity also needs to be integrated with cellular processes including junction formation, cytoskeletal organization, organelle positioning, protein trafficking, and functional specialization of membrane domains. Moreover, polarized cells need to respond to external cues that coordinate polarity at the tissue level. Identifying the protein–protein interactions responsible for integrating polarity with all of these processes remains a major challenge, in part because the mechanisms of polarity control vary in different contexts and with developmental times. Because of their unbiased nature, systematic large-scale protein–protein interaction mapping approaches can be particularly helpful to identify such mechanisms. Here, we discuss methods commonly used to generate proteome-wide interactome maps, with an emphasis on advances in our understanding of cell polarity that have been achieved through application of such methods.     

Testing Wallace's intuition: water type,reproductive isolation and divergence in an Amazonian fish

Alfred Russel Wallace proposed classifying Amazon rivers based on their colour and clarity: white, black and clear water. Wallace also proposed that black waters could mediate diversification and yield distinct fish species. Here, we bring evidence of speciation mediated by water type in the sailfin tetra (Crenuchus spilurus), a fish whose range encompasses rivers of very distinct hydrochemical conditions. Distribution of the two main lineages concords with Wallace's water types: one restricted to the acidic and nutrient‐poor waters of the Negro River (herein Rio Negro lineage) and a second widespread throughout the remaining of the species’ distribution (herein Amazonas lineage). These lineages occur over a very broad geographical range, suggesting that despite occurring in regions separated by thousands of kilometres, individuals of the distinct lineages fail to occupy each other's habitats, hundreds of metres apart and not separated by physical barrier. Reproductive isolation was assessed in isolated pairs exposed to black‐water conditions. All pairs with at least one individual of the lineage not native to black waters showed significantly lower spawning success, suggesting that the water type affected the fitness and contributed to reproductive isolation. Our results endorse Wallace's intuition and highlight the importance of ecological factors in shaping diversity of the Amazon fish fauna.     

Long‐term monitoring of shrub species translocation in degraded Neotropical mountain grassland

The introduction of plant species is a central topic in restoration ecology research. It is an effective technique to restore degraded ecosystems that present low resilience, such as the rupestrian grasslands. Once implemented, the transplantation of native species is monitored only in the short term, whereas long‐term monitoring should be preferred to identify potential changes in the restoration results. Our study is the first assessment of the transplantation success of 10 native shrub species in a degraded area of rupestrian grasslands, 8.5 years after transplantation. Survival, growth, and recruitment were assessed in 2004, 2008, and 2012. For all species, survival, growth, and recruitment varied over time. Although some species exhibited great mortality during the last 4 years, they also showed a great resprouting ability. Our results highlighted a trade‐off between survival and recruitment capacity. Most of the studied species showed remarkable ability to adapt to the extreme environment of the degraded area, persisting either through surviving or recruiting new individuals. We list nine native species, which are well appropriated for rupestrian grasslands restoration. In constrained environments, survival and resistance should represent criteria to select species for restoration project rather than fast growth and ground cover.     

Genetic variation and divergence of Leuciscus pyrenaicus and L. carolitertii (Pisces, Cyprinidae)

The taxonomy of the genus Leuciscus in the Iberian Peninsula has been presented on the basis of morphological analysis. Two species are believed to occur in Portuguese inland waters, L. carolitertii , the northern basins chub, and L. pyrenaicus , which was described for the Tejo and southern basins. Since only slight differences in the meristic and morphometric characters are observed, the distinction between the two species has been made previously mainly on the basis of osteology. In order to investigate the patterns of genetic differentiation between these species, 24 sites were sampled for both species, and examined electrophoretically for the study of variation at 27 presumptive loci. The results pointed to different levels of population differentiation among drainages and support the recognition of the species level for L. pyrenaicus and L. carolitertii. Our results also suggested that the distribution area of L. pyrenaicus is probably restricted to Tejo and to the small drainages near Tejo, while L. carolitertii seems to have a widespread distribution area, including Lima, Douro, Vouga, Mondego, Guadina and Sado drainages. Moreover, concerning the southern populations, Mira and Arade, the surprisingly high level of differentiation observed at several loci, supports the existence of a further species occurring in these small drainages. The evolutionary aspects related to that differentiation are discussed.     

New types of biorelevantα-functional carboxylic acids and their application for peptide modification

Summary New methodology for the preparation of L-isoserine and its incorporation into N- and C-terminal position of peptides is described. Furthermore, the new protective group strategy allows regioselective functional group manipulation in multifunctional amino acids like serine and isoserine.     

Network analyses support the role of prey preferences in shaping resource use patterns within five animal populations

Individual variation is an inherent aspect of animal populations and understanding the mechanisms shaping resource use patterns within populations is crucial to comprehend how individuals partition resources. Theory predicts that differences in prey preferences among consumers and/or differences in the likelihood of adding new resources to their diets are key mechanisms underlying intrapopulation variation in resource use. We developed network models based on optimal diet theory that simulate how individuals consume resources under varying scenarios of individual variation in prey preferences and in the willingness of consuming alternate resources. We then investigated how the structure of individual–resource networks generated under each model compared to the structure of observed networks representing five classical examples of individual diet variation. Our results support the notion that, for the studied populations, individual variation in prey preferences is the major factor explaining patterns in individual–resource networks. In contrast, variation in the willingness of adding prey does not seem to play an important role in shaping patterns of resource use. Individual differences in prey preferences in the studied populations may be generated by complex behavioral rules related to cognitive constraints and experience. Our approach provides a pathway for mapping foraging models into network patterns, which may allow determining the possible mechanisms leading to variation in resource use within populations.