Non‐Visual Mate Choice Ability in a Cavefish (Poecilia mexicana) is not Mechanosensory

One of the most important decisions any female has to make is selecting a mate. In many animals, this involves a strong visual component, but in cave‐dwelling fishes, mate preferences have to be exercised in darkness. In a cave‐dwelling Poeciliid fish, the cave molly (Poecilia mexicana), visual mate choice is still possible because they have functional, albeit reduced eyes. In a previous laboratory study, it was documented that females prefer larger males in light and in darkness. In the present study, we investigated the role of the mechanosensory lateral line in this mate preference. We temporarily knocked out the lateral line using antibiotics. We found that even in the functional absence of the lateral line, females showed a clear preference for larger males, indicating that the lateral line is not crucial for mate choice. This points toward a strong role of chemical communication in cave molly mate choice.     

Different Effects of Nonintercalative Antitumor Drugs on DNA Triple Helix Stability: SN-18071 Promotes Triple Helix Formation

Abstract

The interaction of the nonintercalating bisquaternary ammonium heterocyclic drugs SN- 18071 and SN-6999 with a DNA triple helix has been studied using thermal denaturation and CD spectroscopy. Our data show, that both minor groove binders can bind to the triple helix of poly(dA)-2poly(dT) under comparable ionic conditions, but they influence the stability of the triplex relative to the duplex structure of poly(dA)-poly(dT) in a different manner. SN- 18071, a ligand devoid of forming hydrogen bonds, can promote triplex formation and thermally stabilizes it up to 500 mM Na+ concentration. SN-6999 destabilizes the triplex to duplex equibilirium whereas it stabilizes the duplex. The binding constant of SN-18071 is found to be greater than that to the duplex. The stabilizing effect of SN-18071 is explained by electrostatic inetractions of three ligand molecules with the three grooves of the triple stranded structure. From the experiments it is concluded that SN-6999 binds to the triplex minor groove thereby destabilizing the triplex similar as previously reported for netropsin.     

Ex Vivo - Growth Response of Porcine Small Intestinal Bacterial Communities to Pharmacological Doses of Dietary Zinc Oxide

Piglets were fed diets containing 57 (low) or 2425 (high) mg zinc from analytical grade zinc oxide (ZnO) ·kg⁻¹ feed. Digesta samples from the stomach and jejuna of 32, 39, 46 and 53 d old animals (n  = 6 per group) were incubated in media containing 80, 40, 20 and 0 µg·mL⁻¹ soluble zinc from ZnO. Turbidity was recorded for 16 h and growth parameters were calculated. Additionally, DNA extracts of selected samples were analyzed via qPCR for different bacterial groups. Samples from animals fed the low dietary zinc concentration always showed highest rate of growth and lowest lag times in media without added zinc. However, media supplemented with zinc displayed highest growth rates and lowest lag time in the high dietary zinc group. Specific growth rates and lag time showed significant differences on day 32 and 39 of age, but rarely on days 46 and 53 of age. Bacterial growth in digesta samples from the high dietary zinc group was less influenced by zinc and recovered growth more rapidly than in the low dietary zinc group. Specific growth rates and bacterial cell numbers from qPCR results showed that lactobacilli were most susceptible to zinc, while bifidobacteria, enterobacteria and enterococci exhibited increased growth rates in samples of animals from the high dietary zinc treatment. No treatment related differences were observed for clostridial cluster IV and the Bacteroides-Prevotella-Porphyromonas cluster. The diversity of enterobacteria after incubation was always higher in the high dietary zinc treatment or in medium supplemented with 80 µg·mL⁻¹ soluble ZnO. This study has shown that a pharmacological dosage of ZnO leads to a reduced ex vivo- bacterial growth rate of bacteria from the stomach and jejunum of weaned piglets. In view of the rapid bacterial adaptation to dietary zinc, the administration of ZnO in feeds for weaned piglets might only be beneficial in a short period after weaning.     

High Calcium Bioglass Enhances Differentiation and Survival of Endothelial Progenitor Cells,Inducing Early Vascularization in Critical Size Bone Defects

Early vascularization is a prerequisite for successful bone healing and endothelial progenitor cells (EPC), seeded on appropriate biomaterials, can improve vascularization. The type of biomaterial influences EPC function with bioglass evoking a vascularizing response. In this study the influence of a composite biomaterial based on polylactic acid (PLA) and either 20 or 40% bioglass, BG20 and BG40, respectively, on the differentiation and survival of EPCs in vitro was investigated. Subsequently, the effect of the composite material on early vascularization in a rat calvarial critical size defect model with or without EPCs was evaluated. Human EPCs were cultured with β-TCP, PLA, BG20 or BG40, and seeding efficacy, cell viability, cell morphology and apoptosis were analysed in vitro. BG40 released the most calcium, and improved endothelial differentiation and vitality best. This effect was mimicked by adding an equivalent amount of calcium to the medium and was diminished in the presence of the calcium chelator, EGTA. To analyze the effect of BG40 and EPCs in vivo, a 6-mm diameter critical size calvarial defect was created in rats (n = 12). Controls (n = 6) received BG40 and the treatment group (n = 6) received BG40 seeded with 5×10⁵ rat EPCs. Vascularization after 1 week was significantly improved when EPCs were seeded onto BG40, compared to implanting BG40 alone. This indicates that Ca²⁺ release improves EPC differentiation and is useful for enhanced early vascularization in critical size bone defects.     

PAIN with and without PAR: variants for third-spin assisted heteronuclear polarization transfer

In this article, we describe third-spin assisted heteronuclear recoupling experiments, which play an increasingly important role in measuring long-range heteronuclear couplings, in particular ¹⁵N–¹³C, in proteins. In the proton-assisted insensitive nuclei cross polarization (PAIN-CP) experiment (de Paëpe et al. in J Chem Phys 134:095101, 2011), heteronuclear polarization transfer is always accompanied by homonuclear transfer of the proton-assisted recoupling (PAR) type. We present a phase-alternating experiment that promotes heteronuclear (e.g. ¹⁵N → ¹³C) polarization transfer while simultaneously minimizing homonuclear (e.g.¹³C → ¹³C) transfer (PAIN without PAR). This minimization of homonuclear polarization transfer is based on the principle of the resonant second-order transfer (RESORT) recoupling scheme where the passive proton spins are irradiated by a phase-alternating sequence and the modulation frequency is matched to an integer multiple of the spinning frequency. The similarities and differences between the PAIN-CP and this het-RESORT experiment are discussed here.     

Anchoring and ordering NGS contig assemblies by population sequencing (POPSEQ)

Next‐generation whole‐genome shotgun assemblies of complex genomes are highly useful, but fail to link nearby sequence contigs with each other or provide a linear order of contigs along individual chromosomes. Here, we introduce a strategy based on sequencing progeny of a segregating population that allows de novo production of a genetically anchored linear assembly of the gene space of an organism. We demonstrate the power of the approach by reconstructing the chromosomal organization of the gene space of barley, a large, complex and highly repetitive 5.1 Gb genome. We evaluate the robustness of the new assembly by comparison to a recently released physical and genetic framework of the barley genome, and to various genetically ordered sequence‐based genotypic datasets. The method is independent of the need for any prior sequence resources, and will enable rapid and cost‐efficient establishment of powerful genomic information for many species.     

Adjustment of photosynthetic activity to drought and fluctuating light in wheat

Drought is a major cause of losses in crop yield. Under field conditions, plants exposed to drought are usually also experiencing rapid changes in light intensity. Accordingly, plants need to acclimate to both, drought and light stress. Two crucial mechanisms in plant acclimation to changes in light conditions comprise thylakoid protein phosphorylation and dissipation of light energy as heat by non-photochemical quenching (NPQ). Here, we analyzed the acclimation efficacy of two different wheat varieties, by applying fluctuating light for analysis of plants, which had been subjected to a slowly developing drought stress as it usually occurs in the field. This novel approach allowed us to distinguish four drought phases, which are critical for grain yield, and to discover acclimatory responses which are independent of photodamage. In short-term, under fluctuating light, the slowdown of NPQ relaxation adjusts the photosynthetic activity to the reduced metabolic capacity. In long-term, the photosynthetic machinery acquires a drought-specific configuration by changing the PSII-LHCII phosphorylation pattern together with protein stoichiometry. Therefore, the fine-tuning of NPQ relaxation and PSII-LHCII phosphorylation pattern represent promising traits for future crop breeding strategies.     

Kmasker plants – a tool for assessing complex sequence space in plant species

Many plant genomes display high levels of repetitive sequences. The assembly of these complex genomes using short high‐throughput sequence reads is still a challenging task. Underestimation or disregard of repeat complexity in these datasets can easily misguide downstream analysis. Detection of repetitive regions by k‐mer counting methods has proved to be reliable. Easy‐to‐use applications utilizing k‐mer counting are in high demand, especially in the domain of plants. We present Kmasker plants, a tool that uses k‐mer count information as an assistant throughout the analytical workflow of genome data that is provided as a command‐line and web‐based solution. Beside its core competence to screen and mask repetitive sequences, we have integrated features that enable comparative studies between different cultivars or closely related species and methods that estimate target specificity of guide RNAs for application of site‐directed mutagenesis using Cas9 endonuclease. In addition, we have set up a web service for Kmasker plants that maintains pre‐computed indices for 10 of the economically most important cultivated plants. Source code for Kmasker plants has been made publically available at https://github.com/tschmutzer/kmasker . The web service is accessible at https://kmasker.ipk-gatersleben.de .     

Serum levels of the adipokine chemerin are increased in preeclampsia during and 6 months after pregnancy

Preeclampsia is a serious cardiovascular complication in pregnancy which is associated with an increased future metabolic and cardiovascular risk for mother and newborn. Recently, chemerin was introduced as a novel adipokine inducing insulin resistance in vitro and in vivo. In the current study, we investigated serum concentrations of chemerin by ELISA in control and preeclampsia patients during pregnancy (Control: n=37, preeclampsia: n=37) and 6 months after delivery (Control: n=35, preeclampsia: n=36). Furthermore, the association between chemerin and markers of renal function, glucose and lipid metabolism, as well as inflammation was studied in pregnant patients. Median maternal chemerin concentrations were significantly elevated in preeclampsia patients (249.5 [range: 123.1-366.9] μg/l) as compared to controls (204.8 [138.5-280.8] μg/l) (p<0.001). Furthermore, chemerin serum levels positively correlated with blood pressure, creatinine, free fatty acids, cholesterol, triglycerides (TG), leptin, adiponectin, and C-reactive protein in univariate analyses. In multivariate analyses, TG and leptin remained independently associated with circulating chemerin. Interestingly, median chemerin concentrations 6 months after delivery remained significantly higher in former preeclampsia patients (196.0 [119.8-368.7] μg/l) as compared to controls (152.2 [102.8-216.4] μg/l). Taken together, maternal chemerin serum concentrations are significantly increased in preeclampsia during and after pregnancy. Furthermore, TG and leptin are independent predictors of circulating chemerin during pregnancy.