A novel pathway producing dimethylsulphide in bacteria is widespread in soil environments

The volatile compound dimethylsulphide (DMS) is important in climate regulation, the sulphur cycle and signalling to higher organisms. Microbial catabolism of the marine osmolyte dimethylsulphoniopropionate (DMSP) is thought to be the major biological process generating DMS. Here we report the discovery and characterisation of the first gene for DMSP-independent DMS production in any bacterium. This gene, mddA, encodes a methyltransferase that methylates methanethiol (MeSH) and generates DMS. MddA functions in many taxonomically diverse bacteria including sediment-dwelling pseudomonads, nitrogen-fixing bradyrhizobia and cyanobacteria, and mycobacteria, including the pathogen Mycobacterium tuberculosis. The mddA gene is present in metagenomes from varied environments, being particularly abundant in soil environments, where it is predicted to occur in up to 76% of bacteria. This novel pathway may significantly contribute to global DMS emissions, especially in terrestrial environments, and could represent a shift from the notion that DMSP is the only significant precursor of DMS

Distribution patterns of riodinid butterflies (Lepidoptera: Riodinidae) from southern Brazil

Background: The aim of this study was to synthesize the knowledge of Riodinidae butterflies (Lepidoptera: Papilionoidea) in Rio Grande do Sul state (RS), southern Brazil, evaluating the role of climatic, topographic, and vegetational variables on the observed patterns of occurrence and distribution of these butterflies in the Pampa and Atlantic Forest biomes. The records of riodinid butterflies in RS were collected from published studies and the examination of museum collections in Brazil. Results: A total of 97 taxa of Riodinidae were recorded, distributed in 92 municipalities. The NMDS analysis and the Constrained Analysis of Principal Coordinates grouped the municipalities according to the phytogeographic regions and biomes - Pampa and Atlantic Forest domains - in which the species records were made. Distance from the ocean, precipitation and temperature were the environmental variables which most contributed to explain the distribution patterns of these butterflies. The multivariate Mantel correlogram suggests that over short distances, the composition of species shows significant levels of spatial autocorrelation, and as geographic distance increases, these levels tend to present negative values. Conclusions: The results suggest that the observed distribution pattern of Riodinidae in the different biomes and phytogeographic regions in the extreme southern Brazil could be explained by climatic, environmental variables and geographic distance

Paleodistributions and Comparative Molecular Phylogeography of Leafcutter Ants (Atta spp.) Provide New Insight into the Origins of Amazonian Diversity

The evolutionary basis for high species diversity in tropical regions of the world remains unresolved. Much research has focused on the biogeography of speciation in the Amazon Basin, which harbors the greatest diversity of terrestrial life. The leading hypotheses on allopatric diversification of Amazonian taxa are the Pleistocene refugia, marine incursion, and riverine barrier hypotheses. Recent advances in the fields of phylogeography and species-distribution modeling permit a modern re-evaluation of these hypotheses. Our approach combines comparative, molecular phylogeographic analyses using mitochondrial DNA sequence data with paleodistribution modeling of species ranges at the last glacial maximum (LGM) to test these hypotheses for three co-distributed species of leafcutter ants (Atta spp.). The cumulative results of all tests reject every prediction of the riverine barrier hypothesis, but are unable to reject several predictions of the Pleistocene refugia and marine incursion hypotheses. Coalescent dating analyses suggest that population structure formed recently (Pleistocene-Pliocene), but are unable to reject the possibility that Miocene events may be responsible for structuring populations in two of the three species examined. The available data therefore suggest that either marine incursions in the Miocene or climate changes during the Pleistocene—or both—have shaped the population structure of the three species examined. Our results also reconceptualize the traditional Pleistocene refugia hypothesis, and offer a novel framework for future research into the area

Varying constants, Gravitation and Cosmology

Fundamental constants are a cornerstone of our physical laws. Any constant varying in space and/or time would reflect the existence of an almost massless field that couples to matter. This will induce a violation of the universality of free fall. It is thus of utmost importance for our understanding of gravity and of the domain of validity of general relativity to test for their constancy. We thus detail the relations between the constants, the tests of the local position invariance and of the universality of free fall. We then review the main experimental and observational constraints that have been obtained from atomic clocks, the Oklo phenomenon, Solar system observations, meteorites dating, quasar absorption spectra, stellar physics, pulsar timing, the cosmic microwave background and big bang nucleosynthesis. At each step we describe the basics of each system, its dependence with respect to the constants, the known systematic effects and the most recent constraints that have been obtained. We then describe the main theoretical frameworks in which the low-energy constants may actually be varying and we focus on the unification mechanisms and the relations between the variation of different constants. To finish, we discuss the more speculative possibility of understanding their numerical values and the apparent fine-tuning that they confront us with.Comment: 145 pages, 10 figures, Review for Living Reviews in Relativit

A NEW SPECIES OF ACTINOTE HUBNER FROM THE EASTERN ANDES OF ECUADOR (LEPIDOPTERA: NYMPHALIDAE: HELICONIINAE)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)A new species of Actinote Hubner, A. kennethi Freitas, Willmott and Hall (Lepidoptera: Nymphalidae: Heliconiinae), is described from Cloud forest habitats in eastern Ecuador. Molecular sequence data and morphological characters both indicate that the new taxon is closely related to Actinote g. genitrix d'Almeida, 1922, from southeastern Brazil, and the Venezuelan Actinote genitrix costae Neild, 2008. Based on the Substantial geographic isolation of these taxa, observed morphological differences and mtDNA sequence divergence, we argue for the treatment of the new Ecuadorian Actinote taxon as a distinct species.11114756National Geographic Society [5751-96]Sigma XiNational Science Foundation [0103746, 0639977, 0639861, 0527441]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundo de Apoio ao Ensino a Pesquisa e a Extensao [1659/04]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)National Geographic Society [5751-96]National Science Foundation [0103746, 0639977, 0639861, 0527441]CNPq [CNPq]FAPESP [FA-PESP]FAPESP [98/05101-8]Fundo de Apoio ao Ensino a Pesquisa e a Extensao [1659/04]CNPq [300315/2005-8