The obesity and inflammatory marker haptoglobin attracts monocytes via interaction with chemokine (C-C motif) receptor 2 (CCR2)

Background

Phylogeographic reconstruction of some bacterial populations is hindered by low diversity coupled with high levels of lateral gene transfer. A comparison of recombination levels and diversity at seven housekeeping genes for eleven bacterial species, most of which are commonly cited as having high levels of lateral gene transfer shows that the relative contributions of homologous recombination versus mutation for Burkholderia pseudomallei is over two times higher than for Streptococcus pneumoniae and is thus the highest value yet reported in bacteria. Despite the potential for homologous recombination to increase diversity, B. pseudomallei exhibits a relative lack of diversity at these loci. In these situations, whole genome genotyping of orthologous shared single nucleotide polymorphism loci, discovered using next generation sequencing technologies, can provide very large data sets capable of estimating core phylogenetic relationships. We compared and searched 43 whole genome sequences of B. pseudomallei and its closest relatives for single nucleotide polymorphisms in orthologous shared regions to use in phylogenetic reconstruction.

Results

Bayesian phylogenetic analyses of >14,000 single nucleotide polymorphisms yielded completely resolved trees for these 43 strains with high levels of statistical support. These results enable a better understanding of a separate analysis of population differentiation among >1,700 B. pseudomallei isolates as defined by sequence data from seven housekeeping genes. We analyzed this larger data set for population structure and allele sharing that can be attributed to lateral gene transfer. Our results suggest that despite an almost panmictic population, we can detect two distinct populations of B. pseudomallei that conform to biogeographic patterns found in many plant and animal species. That is, separation along Wallace's Line, a biogeographic boundary between Southeast Asia and Australia.

Conclusion

We describe an Australian origin for B. pseudomallei, characterized by a single introduction event into Southeast Asia during a recent glacial period, and variable levels of lateral gene transfer within populations. These patterns provide insights into mechanisms of genetic diversification in B. pseudomallei and its closest relatives, and provide a framework for integrating the traditionally separate fields of population genetics and phylogenetics for other bacterial species with high levels of lateral gene transfer.     

Different spore structures in sympatric Isoetes histrix populations and their relationship with gross morphology, chromosome number, and ribosomal nuclear ITS sequences

Traditionally, megaspores have supplied the most relevant character for the taxonomy of Isoetes at several systematic levels, including discriminant features usually used in species identification and diagnosis. Isoetes histrix Bory is a terrestrial circum-Mediterranean quillwort characterized by dark, shiny, and persistent phyllopodia with megaspore sporangia completely covered by a velum and tuberculate megaspores. Specimens of this species from Sardinian temporary wetlands showed the sympatric presence of two kinds of individuals with correlated variation in size, ornamentation, and radial ridges of megaspores, and in ornamentation of microspores. However, they showed the same diploid chromosome number (2n = 20), ITS ribotype, and macromorphological feature. No intermediate individuals, showing mixed characters of each spore types as well as malformed or aborted spores have been detected. These results suggest that the gene flow between both kinds of I. histrix plants is heavily restricted, if not limited at all. On the basis of the cytogenetic and molecular uniformity detected in I. histrix in this study, genomic incompatibilities do not seem to be the main reasons involved in the maintenance of the two kinds of I. histrix individuals. Prezygotic barriers involving changes in phenology (e.g. spore maturation) or differential gamete dispersal should be further assessed to gain insights in this topic. The presence of two kinds of individuals in I. histrix differing in significant spore features used in quillwort taxonomy, whatsoever the causes involved in its origin, could be the basis of an incipient differentiation process upon which selective pressures could ultimately lead to speciation.     

Boyer's Reaction and Transetherification: Mechanism and New Perspectives

The progress and stereochemistry of Boyer's reaction were analyzed using several simple, chiral, alcoholic substrates, a variable amount of BiBr₃ and different solvents. Basic solvents inhibit the reaction, while cyclohexane works very well; thus, it was our choice for the present study. In contrast to previous works, BiBr₃ behaves as a true catalyst, being not consumed during the reaction. Although poisoning of the catalyst occurs to some extent, it does not prejudice the reaction yields (>90%). Gas chromatography/mass spectrometry (GC–MS) monitoring of the reaction revealed that, for example, in the presence of alcohol rac-1 , isomeric ethers 4 transetherificate to 3 . We propose a unifying mechanistic model for both Boyer's and transetherification reactions, in which the electronic properties of n‐adducts intermediates, formed by combination of bismuth(III) of BiBr₃ and oxygen atoms of alcohols and ethers, play the key role for both the reactivity and the stereochemical outcome of the reaction. Chirality 28:269–275, 2016. © 2016 Wiley Periodicals, Inc.