Using metabarcoding to compare the suitability of two blood‐feeding leech species for sampling mammalian diversity in North Borneo

The application of high‐throughput sequencing (HTS) for metabarcoding of mixed samples offers new opportunities in conservation biology. Recently, the successful detection of prey DNA from the guts of leeches has raised the possibility that these, and other blood‐feeding invertebrates, might serve as useful samplers of mammals. Yet little is known about whether sympatric leech species differ in their feeding preferences, and whether this has a bearing on their relative suitability for monitoring local mammalian diversity. To address these questions, we collected spatially matched samples of two congeneric leech species Haemadipsa picta and Haemadipsa sumatrana from lowland rainforest in Borneo. For each species, we pooled ~500 leeches into batches of 10 individuals, performed PCR to target a section of the mammalian 16S rRNA locus and undertook sequencing of amplicon libraries using an Illumina MiSeq. In total, we identified sequences from 14 mammalian genera, spanning nine families and five orders. We found greater numbers of detections, and higher diversity of OTUs, in H. picta compared with H. sumatrana, with rodents only present in the former leech species. However, comparison of samples from across the landscape revealed no significant difference in mammal community composition between the leech species. We therefore suggest that H. picta is the more suitable iDNA sampler in this degraded Bornean forest. We conclude that the choice of invertebrate sampler can influence the detectability of different mammal groups and that this should be accounted for when designing iDNA studies.     

Dual RNA-Seq of Human Leprosy Lesions Identifies Bacterial Determinants Linked to Host Immune Response

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Myeloid Cells Restrict MCMV and Drive Stress-Induced Extramedullary Hematopoiesis through STAT1

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Biosynthesis of homoarginine (hArg) and asymmetric dimethylarginine (ADMA) from acutely and chronically administered free <Emphasis Type="SmallCaps">l</Emphasis>-arginine in humans

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthesis, whereas l-arginine (Arg) and l-homoarginine (hArg) serve as substrates for NO synthesis. ADMA and other methylated arginines are generally believed to exclusively derive from guanidine (N ^G)-methylated arginine residues in proteins by protein arginine methyltransferases (PRMTs) that use S-adenosylmethionine (SAM) as the methyl donor. l-Lysine is known for decades as a precursor for hArg, but only recent studies indicate that arginine:glycine amidinotransferase (AGAT) is responsible for the synthesis of hArg. AGAT catalyzes the formation of guanidinoacetate (GAA) that is methylated to creatine by guanidinoacetate methyltransferase (GAMT) which also uses SAM. The aim of the present study was to learn more about the mechanisms of ADMA and hArg formation in humans. Especially, we hypothesized that ADMA is produced by N ^G-methylation of free Arg in addition to the known PRMTs-involving mechanism. In knockout mouse models of AGAT- and GAMT-deficiency, we investigated the contribution of these enzymes to hArg synthesis. Arg infusion (0.5 g/kg, 30 min) in children (n = 11) and ingestion of high-fat protein meals by overweight men (n = 10) were used to study acute effects on ADMA and hArg synthesis. Daily Arg ingestion (10 g) or placebo for 3 or 6 months by patients suffering from peripheral arterial occlusive disease (PAOD, n = 20) or coronary artery disease (CAD, n = 30) was used to study chronic effects of Arg on ADMA synthesis. Mass spectrometric methods were used to measure all biochemical parameters in plasma and urine samples. In mice, AGAT but not GAMT was found to contribute to plasma hArg, while ADMA synthesis was independent of AGAT and GAMT. Arg infusion acutely increased plasma Arg, hArg and ADMA concentrations, but decreased the plasma hArg/ADMA ratio. High-fat protein meals acutely increased plasma Arg, hArg, ADMA concentrations, as well as the plasma hArg/ADMA ratio. In the PAOD and CAD studies, plasma Arg concentration increased in the verum compared to the placebo groups. Plasma ADMA concentration increased only in the PAOD patients who received Arg. Our study suggests that in humans a minor fraction of free Arg is rapidly metabolized to ADMA and hArg. In mice, GAMT and N ^G-methyltransferases contribute to ADMA and hArg synthesis from Arg, whereas AGAT is involved in the synthesis of hArg but not of ADMA. The underlying biochemical mechanisms remain still elusive.     

Moss δ13C: an accurate proxy for past water environments in polar regions

Increased aridity is of global concern. Polar regions provide an opportunity to monitor changes in bioavailable water free of local anthropogenic influences. However, sophisticated proxy measures are needed. We explored the possibility of using stable carbon isotopes in segments of moss as a fine‐scale proxy for past bioavailable water. Variation in δ¹³C with water availability was measured in three species across three peninsulas in the Windmill Islands, East Antarctica and verified using controlled chamber experiments. The δ¹³C from Antarctic mosses accurately recorded long‐term variations in water availability in the field, regardless of location, but significant disparities in δ¹³C between species indicated some make more sensitive proxies. δ¹³C_SUGAR derived from living tissues can change significantly within the span of an Antarctic season (5 weeks) in chambers, but under field conditions, slow growth means that this technique likely represents multiple seasons. δ¹³C_CELLULOSE provides a precise and direct proxy for bioavailable water, allowing reconstructions for coastal Antarctica and potentially other cold regions over past centuries.     

Identifying the molecular and cellular signature of cardiac dilation following myocardial infarction

Establishing molecular and cellular indicators that reflect the extent of dilation of the left ventricle (LV) after myocardial infarction (MI) may improve diagnostic and prognostic capabilities. We queried the Mouse Heart Attack Research Tool (mHART) 1.0 for day 7 post-MI mice (age 3–9 months, untreated males and females) with serial echocardiographic data at days 0, 1, and 7 (n = 51). Mice were classified into two subgroups determined by a median fold change of 1.6 in end-diastolic dimensions (EDD) normalized to pre-MI values; n = 26 fell below (moderate; mean of 1.42 ± 0.01) and n = 25 fell above this cut-off (extreme; mean of 1.79 ± 0.01; p < 0.001 vs. moderate). Plasma proteomic profiling of 34 analytes measured at day 7 post-MI from male mice (n = 12 moderate and 12 extreme) were evaluated as the test dataset, and receiver operating curve (ROC) analysis was used to assess strength of biomarkers. Females (n = 6 moderate and 9 extreme) were used as the validation dataset. Both by t-test and characteristic (ROC) curve analysis, lower macrophage inflammatory protein-1 gamma (MIP-1γ), lymphotactin, and granulocyte chemotactic protein-2 (GCP-2) were identified as plasma indicators for dilation status (p < 0.05 for all). Macrophage numbers were decreased and complement C5, laminin 1, and Ccr8 gene levels were significantly higher in the LV infarcts of the extreme dilation group (p < 0.05 for all). A composite panel including plasma MIP-1γ, lymphotactin, and GCP-2, and LV infarct Ccr8 and macrophage numbers strongly mirrored LV dilation status (AUC = 0.92; p < 0.0001). Using the mHART 1.0 database, we determined that a failure to mount sufficient macrophage-mediated inflammation was indicative of exacerbated LV dilation.     

Development of novel liver X receptor modulators based on a 1,2,4-triazole scaffold

Liver?X?Receptor (LXR) agonists have been reported as a potential treatment for atherosclerosis, Alzheimer’s disease and hepatitis C virus (HCV) infection. We have designed and synthesized a series of potent compounds based on a 1,2,4-triazole scaffold as novel LXR modulators. In cell-based cotransfection assays these compounds generally functioned as LXR agonists and we observed compounds with selectivity towards LXRα (7-fold) and LXRβ (7-fold) in terms of potency. Assessment of the effects of selected compounds on LXR target gene expression in HepG2 cells revealed that compounds 6a-b and 8a-b behaved as inverse agonists on FASN expression even though they were agonists in the LXRα and LXRβ cotransfection assays. Interestingly, these compounds had no effect on the expression of SREBP-1c confirming a unique LXR modulator pharmacology. Molecular docking studies and evaluation of ADME properties in-silico show that active compounds possess favorable binding modes and ADME profiles. Thus, these compounds may be useful for in vivo characterization of LXR modulators with unique profiles and determination of their potential clinical utility.     

Hydration changes accompanying the binding of minor groove ligands with DNA

4',6-diamidino-2-phenylindole (DAPI), netropsin, and pentamidine are minor groove binders that have terminal -C(NH2)2+ groups. The hydration changes that accompany their binding to the minor groove of the (AATT)2 sequence have been studied using the osmotic stress technique with fluorescence spectroscopy. The affinity of DAPI for the binding site decreases with the increasing osmolality of the solution, resulting in acquisition of 35+/-1 waters upon binding. A competition fluorescence assay was utilized to measure the binding constants and hydration changes of the other two ligands, using the DNA-DAPI complex as the fluorescence reporter. Upon their association to the (AATT)2 binding site, netropsin and pentamidine acquire 26+/-3 and 34+/-2 additional waters of hydration, respectively. The hydration changes are discussed in the context of the terminal functional groups of the ligands and conformational changes in the DNA.