The Zn2+ Complex of 1,4,7,10-Tetraazacyclododecane as an Artificial Nucleobase

{2-Deoxy-3-O-[2-cyanoethoxy(diisopropylamino)phosphino]-5-O-(4,4′-dimethoxytrityl)-α-D- erythro-pentofuranosyl}-N-{2-[4,7,10-tris(2,2,2-trifluoroacetyl)-1,4,7,10-tetraazacyclododecan-1- yl]ethyl}acetamide (1) was prepared and incorporated into a 2′-O-methyl oligoribonucleotide. The hybridization of this oligonucleotide with complementary 2′-O-methyl oligoribonucleotides incorporating one to five uracil bases opposite to the azacrown structure was studied in the absence and presence of Zn²⁺. Introduction of Zn²⁺ moderately stabilized the duplex with U-bulged targets.     

Mammalian and Malaria Parasite Cyclase-associated Proteins Catalyze Nucleotide Exchange on G-actin through a Conserved Mechanism

Cyclase-associated proteins (CAPs) are among the most highly conserved regulators of actin dynamics, being present in organisms from mammals to apicomplexan parasites. Yeast, plant, and mammalian CAPs are large multidomain proteins, which catalyze nucleotide exchange on actin monomers from ADP to ATP and recycle actin monomers from actin-depolymerizing factor (ADF)/cofilin for new rounds of filament assembly. However, the mechanism by which CAPs promote nucleotide exchange is not known. Furthermore, how apicomplexan CAPs, which lack many domains present in yeast and mammalian CAPs, contribute to actin dynamics is not understood. We show that, like yeast Srv2/CAP, mouse CAP1 interacts with ADF/cofilin and ADP-G-actin through its N-terminal α-helical and C-terminal β-strand domains, respectively. However, in the variation to yeast Srv2/CAP, mouse CAP1 has two adjacent profilin-binding sites, and it interacts with ATP-actin monomers with high affinity through its WH2 domain. Importantly, we revealed that the C-terminal β-sheet domain of mouse CAP1 is essential and sufficient for catalyzing nucleotide exchange on actin monomers, although the adjacent WH2 domain is not required for this function. Supporting these data, we show that the malaria parasite Plasmodium falciparum CAP, which is entirely composed of the β-sheet domain, efficiently promotes nucleotide exchange on actin monomers. Collectively, this study provides evidence that catalyzing nucleotide exchange on actin monomers via the β-sheet domain is the most highly conserved function of CAPs from mammals to apicomplexan parasites. Other functions, including interactions with profilin and ADF/cofilin, evolved in more complex organisms to adjust the specific role of CAPs in actin dynamics.     

Matrix Metalloproteinases -8 and -9 and Tissue Inhibitor of Metalloproteinase-1 in Burn Patients. A Prospective Observational Study

IntroductionMatrix metalloproteinases (MMPs) -8 and -9 are released from neutrophils in acute inflammation and may contribute to permeability changes in burn injury. In retrospective studies on sepsis, levels of MMP-8, MMP-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) differed from those of healthy controls, and TIMP-1 showed an association with outcome. Our objective was to investigate the relationship between these proteins and disease severity and outcome in burn patients.MethodsIn this prospective, observational, two-center study, we collected plasma samples from admission to day 21 post-burn, and burn blister fluid samples on admission. We compared MMP-8, -9, and TIMP-1 levels between TBSA<20% (N = 19) and TBSA>20% (N = 30) injured patients and healthy controls, and between 90-day survivors and non-survivors. MMP-8, -9, and TIMP-1 levels at 24-48 hours from injury, their maximal levels, and their time-adjusted means were compared between groups. Correlations with clinical parameters and the extent of burn were analyzed. MMP-8, -9, and TIMP-1 levels in burn blister fluids were also studied.ResultsPlasma MMP-8 and -9 were higher in patients than in healthy controls (P<0.001 and P = 0.016), but only MMP-8 differed between the TBSA<20% and TBSA>20% groups. MMP-8 and -9 were not associated with clinical severity or outcome measures. TIMP-1 differed significantly between patients and controls (P<0.001) and between TBSA<20% and TBSA>20% groups (P<0.002). TIMP-1 was associated with 90-day mortality and correlated with the extent of injury and clinical measures of disease severity. TIMP-1 may serve as a new biomarker in outcome prognostication of burn patients.     

Plaque2.0—A High-Throughput Analysis Framework to Score Virus-Cell Transmission and Clonal Cell Expansion

Classical plaque assay measures the propagation of infectious agents across a monolayer of cells. It is dependent on cell lysis, and limited by user-specific settings and low throughput. Here, we developed Plaque2.0, a broadly applicable, fluorescence microscopy-based high-throughput method to mine patho-biological clonal cell features. Plaque2.0 is an open source framework to extract information from chemically fixed cells by immuno-histochemistry or RNA in situ hybridization, or from live cells expressing GFP transgene. Multi-parametric measurements include infection density, intensity, area, shape or location information at single plaque or population levels. Plaque2.0 distinguishes lytic and non-lytic spread of a variety of DNA and RNA viruses, including vaccinia virus, adenovirus and rhinovirus, and can be used to visualize simultaneous plaque formation from co-infecting viruses. Plaque2.0 also analyzes clonal growth of cancer cells, which is relevant for cell migration and metastatic invasion studies. Plaque2.0 is suitable to quantitatively analyze virus infections, vector properties, or cancer cell phenotypes.     

Glacial survival or late glacial colonization? Phylogeography of the root vole (Microtus oeconomus) in north‐west Norway

Aim It has been proposed that the root vole subspecies, Microtus oeconomus finmarchicus, survived the last glacial period on islands on the north‐west coast of Norway. The Norwegian island of Andøya may have constituted the only site with permanent ice‐free conditions. Geological surveys and fossil finds from Andøya demonstrate that survival throughout the last glacial maximum was probably possible for some plants and animals. In this study we aim to infer the recent evolutionary history of Norwegian root vole populations and to evaluate the glacial survival hypothesis. Methods DNA sequence variation in the mitochondrial cytochrome b gene was studied in 46 root voles from 19 localities. Location Northern Fennoscandia and north‐west Russia with a focus on islands on the north‐west coast of Norway. Results The phylogeographical analyses revealed two North European phylogroups labelled ‘Andøya’ and ‘Fennoscandia’. The Andøya phylogroup contained root voles from the Norwegian islands of Andøya, Ringvassøya and Reinøya and two localities in north‐west Russia. The Fennoscandian phylogroup encompassed root voles from the three Norwegian islands of Kvaløya, Håkøya and Arnøya and the remaining specimens from Norway, northern Sweden and Finland. Nucleotide diversity within the Andøya and Fennoscandian phylogroups was similar, ranging from 0.5% to 0.7%. Main conclusions Both our genetic data and previously published morphological data are consistent with in situ glacial survival of root voles on Andøya during the last glacial maximum. However, the level of genetic diversity observed in the extant island populations, the past periods of severe climatic conditions on Andøya and the ecology of the root vole are somewhat difficult to reconcile with this model. A biogeographical scenario involving late glacial recolonization along the northern coasts of Russia and Norway therefore represents a viable alternative. Our results demonstrate that complex recolonization and extinction histories can generate intricate phylogeographical patterns and relatively high levels of genetic variation in northern populations.     

Effects of streptozotocin-induced diabetes and physical training on gene expression of titin-based stretch-sensing complexes in mouse striated muscle

In striated muscle, a sarcomeric noncontractile protein, titin, is proposed to form the backbone of the stress- and strain-sensing structures. We investigated the effects of diabetes, physical training, and their combination on the gene expression of proteins of putative titin stretch-sensing complexes in skeletal and cardiac muscle. Mice were divided into control (C), training (T), streptozotocin-induced diabetic (D), and diabetic training (DT) groups. Training groups performed for 1, 3, or 5 wk of endurance training on a motor-driven treadmill. Muscle samples from T and DT groups together with respective controls were collected 24 h after the last training session. Gene expression of calf muscles (soleus, gastrocnemius, and plantaris) and cardiac muscle were analyzed using microarray and quantitative PCR. Diabetes induced changes in mRNA expression of the proteins of titin stretch-sensing complexes in Z-disc (MLP, myostatin), I-band (CARP, Ankrd2), and M-line (titin kinase signaling). Training alleviated diabetes-induced changes in most affected mRNA levels in skeletal muscle but only one change in cardiac muscle. In conclusion, we showed diabetes-induced changes in mRNA levels of several fiber-type-biased proteins (MLP, myostatin, Ankrd2) in skeletal muscle. These results are consistent with previous observations of diabetes-induced atrophy leading to slower fiber type composition. The ability of exercise to alleviate diabetes-induced changes may indicate slower transition of fiber type.     

Gene, phenotype and function: GLABROUS1 and resistance to herbivory in natural populations of Arabidopsis lyrata

The molecular genetic basis of adaptive variation is of fundamental importance for evolutionary dynamics, but is still poorly known. Only in very few cases has the relationship between genetic variation at the molecular level, phenotype and function been established in natural populations. We examined the functional significance and genetic basis of a polymorphism in production of leaf hairs, trichomes, in the perennial herb Arabidopsis lyrata. Earlier studies suggested that trichome production is subject to divergent selection. Here we show that the production of trichomes is correlated with reduced damage from insect herbivores in natural populations, and using statistical methods developed for medical genetics we document an association between loss of trichome production and mutations in the regulatory gene GLABROUS1. Sequence data suggest that independent mutations in this regulatory gene have provided the basis for parallel evolution of reduced resistance to insect herbivores in different populations of A. lyrata and in the closely related Arabidopsis thaliana. The results show that candidate genes identified in model organisms provide a valuable starting point for analysis of the genetic basis of phenotypic variation in natural populations.     

Human Adenosine A2A Receptor Binds Calmodulin with High Affinity in a Calcium-Dependent Manner

Understanding how ligands bind to G-protein-coupled receptors and how binding changes receptor structure to affect signaling is critical for developing a complete picture of the signal transduction process. The adenosine A2A receptor (A2AR) is a particularly interesting example, as it has an exceptionally long intracellular carboxyl terminus, which is predicted to be mainly disordered. Experimental data on the structure of the A2AR C-terminus is lacking, because published structures of A2AR do not include the C-terminus. Calmodulin has been reported to bind to the A2AR C-terminus, with a possible binding site on helix 8, next to the membrane. The biological meaning of the interaction as well as its calcium dependence, thermodynamic parameters, and organization of the proteins in the complex are unclear. Here, we characterized the structure of the A2AR C-terminus and the A2AR C-terminus-calmodulin complex using different biophysical methods, including native gel and analytical gel filtration, isothermal titration calorimetry, NMR spectroscopy, and small-angle X-ray scattering. We found that the C-terminus is disordered and flexible, and it binds with high affinity (K_d = 98 nM) to calmodulin without major conformational changes in the domain. Calmodulin binds to helix 8 of the A2AR in a calcium-dependent manner that can displace binding of A2AR to lipid vesicles. We also predicted and classified putative calmodulin-binding sites in a larger group of G-protein-coupled receptors.