The present and future of the international wine industry

Wine production is both art and science, a blend of individual creativity and innovative technology. But wine production is also business, with economic factors driving manufacturing practices. To be successful in the modern marketplace, a winemaker must integrate the artistic and economic aspects of wine production, and possess a solid understanding of the intrinsic and extrinsic factors that underlie purchase motivation.     

Functional improvement of dystrophic muscle by myostatin blockade

Mice and cattle with mutations in the myostatin (GDF8) gene show a marked increase in body weight and muscle mass, indicating that this new member of the TGF-beta superfamily is a negative regulator of skeletal muscle growth. Inhibition of the myostatin gene product is predicted to increase muscle mass and improve the disease phenotype in a variety of primary and secondary myopathies. We tested the ability of inhibition of myostatin in vivo to ameliorate the dystrophic phenotype in the mdx mouse model of Duchenne muscular dystrophy (DMD). Blockade of endogenous myostatin by using intraperitoneal injections of blocking antibodies for three months resulted in an increase in body weight, muscle mass, muscle size and absolute muscle strength in mdx mouse muscle along with a significant decrease in muscle degeneration and concentrations of serum creatine kinase. The functional improvement of dystrophic muscle by myostatin blockade provides a novel, pharmacological strategy for treatment of diseases associated with muscle wasting such as DMD, and circumvents the major problems associated with conventional gene therapy in these disorders.     

Microbiology: eukaryotic diversity in Spain's River of Fire

The Rio Tinto, known by the Phoenicians as 'Ur-yero', or 'River of Fire', because of its deep red colour and high acidity, flows through the world's largest pyritic belt in southwestern Spain. Surprisingly, eukaryotic microbes are the principal contributors of biomass in this hostile river, which has a pH of 2 and contains much higher concentrations of heavy metals than are typically found in fresh waters. Here we show that the Rio Tinto shows an unexpected degree of eukaryotic diversity and includes new lineages that we have identified by sequence analysis of genes encoding small-subunit ribosomal RNAs. The diversity of these eukaryotes is much greater than that of prokaryotes, whose metabolism is responsible for the extreme environment.     

A complex systems science perspective on wireless networks

The paper targets a future world where all wireless networks are self-organising entities and in which the predominant mode of spectrum access is dynamic. The paper explores whether the behaviour of a collection of autonomous self-organising wireless systems can be treated as a complex system and whether complex systems science can shed light on the design and deployment of these networks. The authors focus on networks that self-organise from a frequency perspective to understand the behaviour of a collection of wireless self-organising nodes. Each autonomous network is modelled as a cell in a lattice and follows a simple set of self-organisation rules. Two scenarios are considered, one in which each cell is based on cellular automata and which provides an abstracted view of interference and a second in which each cell uses a self-organising technique which more accurately accounts for interference. The authors use excess entropy to measure complexity and in combination with entropy gain an understanding of the structure emerging in the lattice for the self-organising networks. The authors show that the self-organising systems presented here do exhibit complex behaviour. Finally, the authors look at the robustness of these complex systems and show that they are robust against changes in the environment.     

Phylogenetic relationship of the Brasilian leptodactylid frog generaCraspedoglossa,Cycloramphus andZachaenus

Summary Based on immunological comparisons of the serum albumins ofCraspedoglossa andZachaenus with antisera to albumin of several species ofCycloramphus, it is concluded that morphological and biochemical evolutionary rates have not been comparable within the study group. Taken together, the morphological and biochemical information demonstrate that whileZachaenus is a genetic member of theCycloramphus lineage, it has attained generic status.This study was supported by NSF grant No. DEB78-23396, the Amazon Ecosystem Research Program, Smithsonian Institution, the Fluid Research Fund, Smithsonian Institution, and the Museu de Zoologia da Universidade de São Paulo.The authors gratefully acknowledge the following colleagues for their help in procuring frog samples: R.I. Crombie, M.C. Duchêne, F.I. McCullough, F.C. do Val and P.E. Vanzolini.     

Biodiversity and biogeography of phages in modern stromatolites and thrombolites

Viruses, and more particularly phages (viruses that infect bacteria), represent one of the most abundant living entities in aquatic and terrestrial environments. The biogeography of phages has only recently been investigated and so far reveals a cosmopolitan distribution of phage genetic material (or genotypes). Here we address this cosmopolitan distribution through the analysis of phage communities in modern microbialites, the living representatives of one of the most ancient life forms on Earth. On the basis of a comparative metagenomic analysis of viral communities associated with marine (Highborne Cay, Bahamas) and freshwater (Pozas Azules II and Rio Mesquites, Mexico) microbialites, we show that some phage genotypes are geographically restricted. The high percentage of unknown sequences recovered from the three metagenomes (>97%), the low percentage similarities with sequences from other environmental viral (n = 42) and microbial (n = 36) metagenomes, and the absence of viral genotypes shared among microbialites indicate that viruses are genetically unique in these environments. Identifiable sequences in the Highborne Cay metagenome were dominated by single-stranded DNA microphages that were not detected in any other samples examined, including sea water, fresh water, sediment, terrestrial, extreme, metazoan-associated and marine microbial mats. Finally, a marine signature was present in the phage community of the Pozas Azules II microbialites, even though this environment has not been in contact with the ocean for tens of millions of years. Taken together, these results prove that viruses in modern microbialites display biogeographical variability and suggest that they may be derived from an ancient community.     

Reconstitution of a microtubule plus-end tracking system in vitro

The microtubule cytoskeleton is essential to cell morphogenesis. Growing microtubule plus ends have emerged as dynamic regulatory sites in which specialized proteins, called plus-end-binding proteins (+TIPs), bind and regulate the proper functioning of microtubules. However, the molecular mechanism of plus-end association by +TIPs and their ability to track the growing end are not well understood. Here we report the in vitro reconstitution of a minimal plus-end tracking system consisting of the three fission yeast proteins Mal3, Tip1 and the kinesin Tea2. Using time-lapse total internal reflection fluorescence microscopy, we show that the EB1 homologue Mal3 has an enhanced affinity for growing microtubule end structures as opposed to the microtubule lattice. This allows it to track growing microtubule ends autonomously by an end recognition mechanism. In addition, Mal3 acts as a factor that mediates loading of the processive motor Tea2 and its cargo, the Clip170 homologue Tip1, onto the microtubule lattice. The interaction of all three proteins is required for the selective tracking of growing microtubule plus ends by both Tea2 and Tip1. Our results dissect the collective interactions of the constituents of this plus-end tracking system and show how these interactions lead to the emergence of its dynamic behaviour. We expect that such in vitro reconstitutions will also be essential for the mechanistic dissection of other plus-end tracking systems.     

Incipient speciation by divergent adaptation and antagonistic epistasis in yeast

Establishing the conditions that promote the evolution of reproductive isolation and speciation has long been a goal in evolutionary biology. In ecological speciation, reproductive isolation between populations evolves as a by-product of divergent selection and the resulting environment-specific adaptations. The leading genetic model of reproductive isolation predicts that hybrid inferiority is caused by antagonistic epistasis between incompatible alleles at interacting loci. The fundamental link between divergent adaptation and reproductive isolation through genetic incompatibilities has been predicted, but has not been directly demonstrated experimentally. Here we empirically tested key predictions of speciation theory by evolving the initial stages of speciation in experimental populations of the yeast Saccharomyces cerevisiae. After replicate populations adapted to two divergent environments, we consistently observed the evolution of two forms of postzygotic isolation in hybrids: reduced rate of mitotic reproduction and reduced efficiency of meiotic reproduction. This divergent selection resulted in greater reproductive isolation than parallel selection, as predicted by the ecological speciation theory. Our experimental system allowed controlled comparison of the relative importance of ecological and genetic isolation, and we demonstrated that hybrid inferiority can be ecological and/or genetic in basis. Overall, our results show that adaptation to divergent environments promotes the evolution of reproductive isolation through antagonistic epistasis, providing evidence of a plausible common avenue to speciation and adaptive radiation in nature.