Listening In on the Past: What Can Otolith δ18O Values Really Tell Us about the Environmental History of Fishes?

Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory data gathered from a decade using archival tags to study the behaviour of adult plaice (Pleuronectes platessa L.) in the North Sea. Based on the tag-derived monthly distributions of the fish and corresponding temperature and salinity estimates modelled across three consecutive years, we first predicted annual otolith δ18O values for three geographically discrete offshore sub-stocks, using three alternative plausible scenarios for otolith growth. Comparison of predicted vs. measured annual δ18O values demonstrated >96% correct prediction of sub-stock membership, irrespective of the otolith growth scenario. Pronounced inter-stock differences in δ18O values, notably in summer, provide a robust marker for reconstructing broad-scale plaice distribution in the North Sea. However, although largely congruent, measured and predicted annual δ18O values of did not fully match. Small, but consistent, offsets were also observed between individual high-resolution otolith δ18O values measured during tag recording time and corresponding δ18O predictions using concomitant tag-recorded temperatures and location-specific salinity estimates. The nature of the shifts differed among sub-stocks, suggesting specific vital effects linked to variation in physiological response to temperature. Therefore, although otolith δ18O in free-ranging fish largely reflects environmental temperature and salinity, we counsel prudence when interpreting otolith δ18O data for stock discrimination or temperature reconstruction until the mechanisms underpinning otolith δ18O signature acquisition, and associated variation, are clarified

Effects of adult exposure to bisphenol A on genes involved in the physiopathology of rat prefrontal cortex

Several neurological and behavioral dysfunctions have been reported in animals exposed to bisphenol A (BPA). However, little is known about the impact of adult exposure to BPA on brain physiopathology. Here, we focused on prefrontal cortex (PFC) of rats, because it is an important area for cognitive control, complex behaviors and is altered in many psychopathologies. Gamma-aminobutyric acid (GABA) and serotonin (5-HT) systems are essential for PFC function. Therefore, we examined the effects of adult exposure to BPA on 5α-Reductase (5α-R) and cytochrome P450 aromatase (P450arom), enzymes that synthesize GABAA receptor modulators, and tryptophan hydroxylase (Tph), the rate-limiting enzyme in 5-HT biosynthesis. To gain better understanding of BPA’s action in the adult PFC, 84 genes involved in neurotoxicity were also analysed. Adult male and female rats were subcutaneously injected for 4 days with 50 µg/kg/day, the current reference safe dose for BPA. mRNA and protein levels of 5α-R, P450arom and Tph were quantified by real-time RT-PCR and Western blot. Genes linked to neurotoxicity were analyzed by PCR-Array technology. Adult exposure to BPA increased both P450arom and Tph2 expression in PFC of male and female, but decreased 5α-R1 expression in female. Moreover, we identified 17 genes related to PFC functions such as synaptic plasticity and memory, as potential targets of BPA. Our results provided new insights on the molecular mechanisms underlying BPA action in the physiopathology of PFC, but also raise the question about the safety of short-term exposure to it in the adulthood.This research was supported by grants from Ministerio de Ciencia e Innovación (BFU2008-05340) and by the Junta de Andalucía (CTS202-Endocronología y Metabolismo)

Cell Culture Replication of a Genotype 1b Hepatitis C Virus Isolate Cloned from a Patient Who Underwent Liver Transplantation

The introduction of the genotype 2a isolate JFH1 was a major breakthrough in the field of hepatitis C virus (HCV), allowing researchers to study the complete life cycle of the virus in cell culture. However, fully competent culture systems encompassing the most therapeutically relevant HCV genotypes are still lacking, especially for the highly drug-resistant genotype 1b. For most isolated HCV clones, efficient replication in cultured hepatoma cells requires the introduction of replication-enhancing mutations. However, such mutations may interfere with viral assembly, as occurs in the case of the genotype 1b isolate Con1. In this study, we show that a clinical serum carrying a genotype 1b virus with an exceptionally high viral load was able to infect Huh7.5 cells. Similar to previous reports, inoculation of Huh7.5 cells by natural virus is very inefficient compared to infection by cell culture HCV. A consensus sequence of a new genotype 1b HCV isolate was cloned from the clinical serum (designated Barcelona HCV1), and then subjected to replication studies. This virus replicated poorly in a transient fashion in Huh7.5 cells after electroporation with in vitro transcribed RNA. Nonetheless, approximately 3 weeks post electroporation and thereafter, core protein-positive cells were detected by immunofluorescence. Surprisingly, small amounts of core protein were also measurable in the supernatant of electroporated cells, suggesting that HCV particles might be assembled and released. Our findings not only enhance the current method of cloning in vitro HCV replication-competent isolates, but also offer valuable insights for the realization of fully competent culture systems for HCV

Protein Kinase C Iota Regulates Pancreatic Acinar-to-Ductal Metaplasia

Pancreatic acinar-to-ductal metaplasia (ADM) is associated with an increased risk of pancreatic cancer and is considered a precursor of pancreatic ductal adenocarcinoma. Transgenic expression of transforming growth factor alpha (TGF-α) or K-rasG12D in mouse pancreatic epithelium induces ADM in vivo. Protein kinase C iota (PKCι) is highly expressed in human pancreatic cancer and is required for the transformed growth and tumorigenesis of pancreatic cancer cells. In this study, PKCι expression was assessed in a mouse model of K-rasG12D-induced pancreatic ADM and pancreatic cancer. The ability of K-rasG12D to induce pancreatic ADM in explant culture, and the requirement for PKCι, was investigated. PKCι is elevated in human and mouse pancreatic ADM and intraepithelial neoplastic lesions in vivo. We demonstrate that K-rasG12D is sufficient to induce pancreatic ADM in explant culture, exhibiting many of the same morphologic and biochemical alterations observed in TGF-α-induced ADM, including a dependence on Notch activation. PKCι is highly expressed in both TGF-α- and K-rasG12D-induced pancreatic ADM and inhibition of PKCι significantly reduces TGF-α- and K-rasG12D-mediated ADM. Inhibition of PKCι suppresses K-rasG12D–induced MMP-7 expression and Notch activation, and exogenous MMP-7 restores K-rasG12D–mediated ADM in PKCι-depleted cells, implicating a K-rasG12D-PKCι-MMP-7 signaling axis that likely induces ADM through Notch activation. Our results indicate that PKCι is an early marker of pancreatic neoplasia and suggest that PKCι is a potential downstream target of K-rasG12D in pancreatic ductal metaplasia in vivo

Interactions between Casein Kinase Iε (CKIε) and Two Substrates from Disparate Signaling Pathways Reveal Mechanisms for Substrate-Kinase Specificity

Members of the Casein Kinase I (CKI) family of serine/threonine kinases regulate diverse biological pathways. The seven mammalian CKI isoforms contain a highly conserved kinase domain and divergent amino- and carboxy-termini. Although they share a preferred target recognition sequence and have overlapping expression patterns, individual isoforms often have specific substrates. In an effort to determine how substrates recognize differences between CKI isoforms, we have examined the interaction between CKIepsilon and two substrates from different signaling pathways.CKIepsilon, but not CKIalpha, binds to and phosphorylates two proteins: Period, a transcriptional regulator of the circadian rhythms pathway, and Disheveled, an activator of the planar cell polarity pathway. We use GST-pull-down assays data to show that two key residues in CKIalpha's kinase domain prevent Disheveled and Period from binding. We also show that the unique C-terminus of CKIepsilon does not determine Dishevelled's and Period's preference for CKIepsilon nor is it essential for binding, but instead plays an auxillary role in stabilizing the interactions of CKIepsilon with its substrates. We demonstrate that autophosphorylation of CKIepsilon's C-terminal tail prevents substrate binding, and use mass spectrometry and chemical crosslinking to reveal how a phosphorylation-dependent interaction between the C-terminal tail and the kinase domain prevents substrate phosphorylation and binding.The biochemical interactions between CKIepsilon and Disheveled, Period, and its own C-terminus lead to models that explain CKIepsilon's specificity and regulation

Comparison of polypeptides that bind the transferrin receptor for targeting gold nanocarriers

The ability to target therapeutic agents to specific tissues is an important element in the development of new disease treatments. The transferrin receptor (TfR) is one potential target for drug delivery, as it expressed on many dividing cells and on brain endothelium, the key cellular component of the blood-brain barrier. The aim of this study was to compare a set of new and previously-described polypeptides for their ability to bind to brain endothelium, and investigate their potential for targeting therapeutic agents to the CNS. Six polypeptides were ranked for their rate of endocytosis by the human brain endothelial cell line hCMEC/D3 and the murine line bEnd.3. One linear polypeptide and two cyclic polypeptides showed high rates of uptake. These peptides were investigated to determine whether serum components, including transferrin itself affected uptake by the endothelium. One of the cyclic peptides was strongly inhibited by transferrin and the other cyclic peptide weakly inhibited. As proof of principle the linear peptide was attached to 2nm glucose coated gold-nanoparticles, and the rate of uptake of the nanoparticles measured in a hydrogel model of the blood-brain barrier. Attachment of the TfR-targeting polypeptide significantly increased the rates of endocytosis by brain endothelium and increased movement of nanoparticles across the cells

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta