Co-Transport of Polycyclic Aromatic Hydrocarbons by Motile Microorganisms Leads to Enhanced Mass Transfer under Diffusive Conditions.

The environmental chemodynamics of hydrophobic organic chemicals (HOCs) are often rate-limited by diffusion in stagnant boundary layers. This study investigated whether motile microorganisms can act as microbial carriers that enhance mass transfer of HOCs through diffusive boundary layers. A new experimental system was developed that allows (1) generation of concentration gradients of HOCs under the microscope, (2) exposure and direct observation of microorganisms in such gradients, and (3) quantification of HOC mass transfer. Silicone O-rings were integrated into a Dunn chemotaxis chamber to serve as sink and source for polycyclic aromatic hydrocarbons (PAHs). This resulted in stable concentration gradients in water (>24 h). Adding the model organism <i>Tetrahymena pyriformis</i> to the experimental system enhanced PAH mass transfer up to hundred-fold (benzo­[a]­pyrene). Increasing mass transfer enhancement with hydrophobicity indicated PAH co-transport with the motile organisms. Fluorescence microscopy confirmed such transport. The effective diffusivity of <i>T. pyriformis</i>, determined by video imaging microscopy, was found to exceed molecular diffusivities of the PAHs up to four-fold. Cell-bound PAH fractions were determined to range from 28% (naphthalene) to 92% (pyrene). Motile microorganisms can therefore function as effective carriers for HOCs under diffusive conditions and might significantly enhance mobility and availability of HOCs

Timing of embryonic quiescence determines viability of embryos from the calanoid copepod, Acartia tonsa (Dana)

<div><p>Like 41 other calanoid copepods, <i>Acartia tonsa</i>, are capable of inducing embryonic quiescence when experiencing unfavorable environmental conditions. The ecdysone-signaling cascade is known to have a key function in developmental processes like embryogenesis and molting of arthropods, including copepods. We examined the role of <i>ecdysteroid-phosphate phosphatase</i> (<i>EPPase</i>), <i>ecdysone receptor</i> (<i>EcR</i>), <i>ß fushi tarazu transcription factor 1</i> (<i>ßFTZ-F1</i>), and the <i>ecdysteroid-regulated early gene E74</i> (<i>E74</i>), which represent different levels of the ecdysone-signaling cascade in our calanoid model organism. Progression of embryogenesis was monitored and hatching success determined to evaluate viability. Embryos that were induced quiescence before the gastrulation stage would stay in gastrulation during the rest of quiescence and exhibited a slower pace of hatching as compared to subitaneous embryos. In contrast, embryos developed further than gastrulation would stay in gastrulation or later stages during quiescence and showed a rapid pace in hatching after quiescence termination. Expression patterns suggested two peaks of the biological active ecdysteroids, 20-hydroxyecdysone (20E). The first peak of 20E was expressed in concert with the beginning of embryogenesis originating from yolk-conjugated ecdysteroids, based on <i>EPPase</i> expression. The second peak is suggested to originate from <i>de novo</i> synthesized 20E around the limb bud stage. During quiescence, the expression patterns of <i>EPPase</i>, <i>EcR</i>, <i>ßFTZ-F1</i>, and <i>E74</i> were either decreasing or not changing over time. This suggests that the ecdysone-signaling pathway play a key role in the subitaneous development of <i>A</i>. <i>tonsa</i> embryogenesis, but not during quiescence. The observation is of profound ecological and practical relevance for the dynamics of egg banks.</p></div

Role of PACAP and VIP Signalling in Regulation of Chondrogenesis and Osteogenesis

Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are multifunctional proteins that can regulate diverse physiological processes. These are also regarded as neurotrophic and anti-inflammatory substances in the CNS, and PACAP is reported to prevent harmful effects of oxidative stress. In the last decade more and more data accumulated on the similar function of PACAP in various tissues, but its cartilage- and bone-related presence and functions have not been widely investigated yet. In this summary we plan to verify the presence and function of PACAP and VIP signalling tool kit during cartilage differentiation and bone formation. We give evidence about the protective function of PACAP in cartilage regeneration with oxidative or mechanically stress and also with the modulation of PACAP signalling in vitro in osteogenic cells. Our observations imply the therapeutic perspective that PACAP might be applicable as a natural agent exerting protecting effect during joint inflammation and/or may promote cartilage regeneration during degenerative diseases of articular cartilage

Eggs of the copepod Acartia tonsa Dana require hypoxic conditions to tolerate prolonged embryonic development arrest

Additional file 1. Raw data and calculations for all experiments as well as an overview of experiments in this study

Regulation of the DNA Damage Response and Gene Expression by the Dot1L Histone Methyltransferase and the 53Bp1 Tumour Suppressor

Dot1L, a histone methyltransferase that targets histone H3 lysine 79 (H3K79), has been implicated in gene regulation and the DNA damage response although its functions in these processes remain poorly defined.Using the chicken DT40 model system, we generated cells in which the Dot1L gene is disrupted to examine the function and focal recruitment of the 53Bp1 DNA damage response protein. Detailed kinetic and dose response assays demonstrate that, despite the absence of H3K79 methylation demonstrated by mass spectrometry, 53Bp1 focal recruitment is not compromised in these cells. We also describe, for the first time, the phenotypes of a cell line lacking both Dot1L and 53Bp1. Dot1L⁻/⁻ and wild type cells are equally resistant to ionising radiation, whereas 53Bp1⁻/⁻/Dot1L⁻/⁻ cells display a striking DNA damage resistance phenotype. Dot1L and 53Bp1 also affect the expression of many genes. Loss of Dot1L activity dramatically alters the mRNA levels of over 1200 genes involved in diverse biological functions. These results, combined with the previously reported list of differentially expressed genes in mouse ES cells knocked down for Dot1L, demonstrates surprising cell type and species conservation of Dot1L-dependent gene expression. In 53Bp1⁻/⁻ cells, over 300 genes, many with functions in immune responses and apoptosis, were differentially expressed. To date, this is the first global analysis of gene expression in a 53Bp1-deficient cell line.Taken together, our results uncover a negative role for Dot1L and H3K79 methylation in the DNA damage response in the absence of 53Bp1. They also enlighten the roles of Dot1L and 53Bp1 in gene expression and the control of DNA double-strand repair pathways in the context of chromatin

Age at Menarche and Time Spent in Education: A Mendelian Randomization Study.

Menarche signifies the primary event in female puberty and is associated with changes in self-identity. It is not clear whether earlier puberty causes girls to spend less time in education. Observational studies on this topic are likely to be affected by confounding environmental factors. The Mendelian randomization (MR) approach addresses these issues by using genetic variants (such as single nucleotide polymorphisms, SNPs) as proxies for the risk factor of interest. We use this technique to explore whether there is a causal effect of age at menarche on time spent in education. Instruments and SNP-age at menarche estimates are identified from a Genome Wide Association Study (GWAS) meta-analysis of 182,416 women of European descent. The effects of instruments on time spent in education are estimated using a GWAS meta-analysis of 118,443 women performed by the Social Science Genetic Association Consortium (SSGAC). In our main analysis, we demonstrate a small but statistically significant causal effect of age at menarche on time spent in education: a 1 year increase in age at menarche is associated with 0.14 years (53 days) increase in time spent in education (95% CI 0.10-0.21 years, p = 3.5 × 10-8). The causal effect is confirmed in sensitivity analyses. In identifying this positive causal effect of age at menarche on time spent in education, we offer further insight into the social effects of puberty in girls

Contribution for the derivation of a soil screening value (SSV) for uranium, using a natural reference soil

In order to regulate the management of contaminated land, many countries have been deriving soil screening values (SSV). However, the ecotoxicological data available for uranium is still insufficient and incapable to generate SSVs for European soils. In this sense, and so as to make up for this shortcoming, a battery of ecotoxicological assays focusing on soil functions and organisms, and a wide range of endpoints was carried out, using a natural soil artificially spiked with uranium. In terrestrial ecotoxicology, it is widely recognized that soils have different properties that can influence the bioavailability and the toxicity of chemicals. In this context, SSVs derived for artificial soils or for other types of natural soils, may lead to unfeasible environmental risk assessment. Hence, the use of natural regional representative soils is of great importance in the derivation of SSVs. A Portuguese natural reference soil PTRS1, from a granitic region, was thereby applied as test substrate. This study allowed the determination of NOEC, LOEC, EC20 and EC50 values for uranium. Dehydrogenase and urease enzymes displayed the lowest values (34.9 and ,134.5 mg U Kg, respectively). Eisenia andrei and Enchytraeus crypticus revealed to be more sensitive to uranium than Folsomia candida. EC50 values of 631.00, 518.65 and 851.64 mg U Kg were recorded for the three species, respectively. Concerning plants, only Lactuca sativa was affected by U at concentrations up to 1000 mg U kg1. The outcomes of the study may in part be constrained by physical and chemical characteristics of soils, hence contributing to the discrepancy between the toxicity data generated in this study and that available in the literature. Following the assessment factor method, a predicted no effect concentration (PNEC) value of 15.5 mg kg21dw was obtained for U. This PNEC value is proposed as a SSV for soils similar to the PTRS1