The Hyalella (Crustacea: Amphipoda) species cloud of the ancient Lake Titicaca originated from multiple colonizations

The final publication is available at Elsevier via https://doi.org/10.1016/j.ympev.2018.03.004. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12–20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.Natural Sciences and Engineering Research Council || Discovery Grant 2012-327509Natural Sciences and Engineering Research Council || Discovery Grant 386591-2010Natural Sciences and Engineering Research Council || Undergraduate Student Research AwardsNatural Sciences and Engineering Research Council || Postdoctoral FellowshipCatholic University of Temuco, Research Direction || Limnology Project DGI-DCA 2007-01, Project MECESUP UCT 080

Isohexide derivatives from renewable resources as chiral building blocks

The combination of rapidly depleting fossil resources and growing concerns about greenhouse gas emissions and global warming have stimulated extensive research on the use of biomass for energy, fuels, and chemicals.[1] Although biobased chemicals have the potential to reduce the amount of fossil feedstock consumed in the chemical industry today, the most abundant type of biobased feedstock, that is, carbohydrates, is often unsuitable for current high-temperature industrial chemical processes. Compared to hydrophobic aliphatic or aromatic feedstocks with a low degree of functionalization, carbohydrates such as polysaccharides are complex, overfunctionalized hydrophilic materials. One approach to overcome these drawbacks is to reduce the number of functional groups, resulting in more stable, industrially applicable bifunctional biobased building blocks,[2] such as furan-2,5-dicarboxylic acid,[3] levulinic acid,[4] and isosorbide.[5] Isosorbide (1,4:3,6-dianhydrosorbitol) is a rigid bicyclic diol that is derived from sorbitol and can ultimately be obtained from glucose-based polysaccharides such as starch and cellulose.[6] Apart from isosorbide, in which the hydroxyl groups on C2 and C5 are in the exo and endo positions, respectively, two other isohexides are known (Figure 1): the symmetrical endo-endo isomer isomannide (1,4:3,6-dianhydromannitol) and the exo-exo isomer isoidide (1,4:3,6-dianhydroiditol), derived from d-mannitol and l-iditol, respectively

A CRISPR-Cas system enhances envelope integrity mediating antibiotic resistance and inflammasome evasion

Clustered, regularly interspaced, short palindromic repeats-CRISPR associated (CRISPR-Cas) systems defend bacteria against foreign nucleic acids, such as during bacteriophage infection and transformation, processes which cause envelope stress. It is unclear if these machineries enhance membrane integrity to combat this stress. Here, we show that the Cas9-dependent CRISPR-Cas system of the intracellular bacterial pathogen Francisella novicida is involved in enhancing envelope integrity through the regulation of a bacterial lipoprotein. This action ultimately provides increased resistance to numerous membrane stressors, including antibiotics. We further find that this previously unappreciated function of Cas9 is critical during infection, as it promotes evasion of the host innate immune absent in melanoma 2/apoptosis associated speck-like protein containing a CARD (AIM2/ASC) inflammasome. Interestingly, the attenuation of the cas9 mutant is complemented only in mice lacking both the AIM2/ASC inflammasome and the bacterial lipoprotein sensor Toll-like receptor 2, but not in single knockout mice, demonstrating that Cas9 is essential for evasion of both pathways. These data represent a paradigm shift in our understanding of the function of CRISPR-Cas systems as regulators of bacterial physiology and provide a framework with which to investigate the roles of these systems in myriad bacteria, including pathogens and commensals

Revista mexicana de psicología

The folate analogues methotrexate, aminopterin and pyrimethamine were toxic when fed in a blood meal to adult buffalo flies (Haematobia irritans exigua), but aminopterin caused greater mortality than methotrexate, while trimethoprim was not toxic to adult flies. This is the first recorded instance of mortality in adult insects caused by ingestion of folate analogues. In order to investigate the mechanism of this toxicity, the dihydrofolate reductase (DHFR) gene was cloned from adult buffalo fly cDNA using a PCR-based approach. The full-length DHFR coding sequence (BF-DHFR) was 887 bp and contained an open reading frame encoding a protein of 188 amino acids. The deduced protein sequence identities between BF-DHFR and the other known insect DHFR sequences were: Drosophila melanogaster, 75%; Aedes albopictus, 54%; Heliothis virescens, 43%. The BF-DHFR gene has a single 52 bp intron, an organization more similar to Dipteran species (Drosophila and Aedes).The cDNA encoding BF-DHFR was inserted into an Escherichia coli expression vector and the recombinant protein was expressed to levels representing about 25% of total cell protein. The active enzyme was purified by affinity chromatography on methotrexate-agarose and displayed a relatively low affinity (IC = 30 nM) for methotrexate

Genome-wide study identifies two loci associated with lung function decline in mild to moderate COPD

Accelerated lung function decline is a key COPD phenotype; however, its genetic control remains largely unknown. We performed a genome-wide association study using the Illumina Human660W-Quad v.1_A BeadChip. Generalized estimation equations were used to assess genetic contributions to lung function decline over a 5-year period in 4,048 European American Lung Health Study participants with largely mild COPD. Genotype imputation was performed using reference HapMap II data. To validate regions meeting genome-wide significance, replication of top SNPs was attempted in independent cohorts. Three genes (TMEM26, ANK3 and FOXA1) within the regions of interest were selected for tissue expression studies using immunohistochemistry. Two intergenic SNPs (rs10761570, rs7911302) on chromosome 10 and one SNP on chromosome 14 (rs177852) met genome-wide significance after Bonferroni. Further support for the chromosome 10 region was obtained by imputation, the most significantly associated imputed SNPs (rs10761571, rs7896712) being flanked by observed markers rs10761570 and rs7911302. Results were not replicated in four general population cohorts or a smaller cohort of subjects with moderate to severe COPD; however, we show novel expression of genes near regions of significantly associated SNPS, including TMEM26 and FOXA1 in airway epithelium and lung parenchyma, and ANK3 in alveolar macrophages. Levels of expression were associated with lung function and COPD status. We identified two novel regions associated with lung function decline in mild COPD. Genes within these regions were expressed in relevant lung cells and their expression related to airflow limitation suggesting they may represent novel candidate genes for COPD susceptibility