Secretogranin II: Relative Amounts and Processing to Secretoneurin in Various Rat Tissues

Abstract: Secretoneurin is a 33-amino-acid peptide produced in vivo from secretogranin II. An antiserum raised against this peptide recognizes both the free peptide and its precursors. By HPLC and radioimmunoassay we characterized the immunoreactive molecules and determined the levels of immunoreactivity in various rat organs. In adrenal medulla and to a lesser degree in the anterior pituitary processing of secretogranin II to secretoneurin was very limited, whereas in all other organs studied (brain, intestine, endocrine pancreas, thyroid gland, and posterior pituitary) a high degree of processing was apparent. Thus, practically all of the immunoreactivity was present as free secretoneurin. This was also true for serum. When the total amount of secretoneurin immunoreactivity was calculated for the various organs, the largest pools in descending order were in the intestine, CNS, anterior pituitary, pancreas, and adrenal gland. This makes it likely that secretoneurin in serum is mainly derived from the intestine. The high degree of processing of secretogranin II in most organs is consistent with the concept that this protein acts as a precursor of a functional peptide, i.e., secretoneurin.     

EXPOSE, an Astrobiological Exposure Facility on the International Space Station - from Proposal to Flight

Following an European Space Agency announcement of opportunity in 1996 for ”Externally mounted payloads for 1st utilization phase” on the International Space Station (ISS), scientists working in the fields of astrobiology proposed experiments aiming at long-term exposure of a variety of chemical compounds and extremely resistant microorganisms to the hostile space environment. The ESA exposure facility EXPOSE was built and an operations´ concept was prepared. The EXPOSE experiments were developed through an intensive pre-flight experiment verification test program. 12 years later, two sets of astrobiological experiments in two EXPOSE facilities have been successfully launched to the ISS for external exposure for up to 1.5 years. EXPOSE-E, now installed at the balcony of the European Columbus module, was launched in February 2008, while EXPOSE-R took off to the ISS in November 2008 and was installed on the external URM-D platform of the Russian Zvezda module in March 2009.     

A Solution‐Processable Polymer Photocatalyst for Hydrogen Evolution from Water

Direct photocatalytic water splitting is an attractive strategy for clean energy production, but multicomponent nanostructured systems that mimic natural photosynthesis can be difficult to fabricate because of the insolubility of most photocatalysts. Here, a solution‐processable organic polymer is reported that is a good photocatalyst for hydrogen evolution from water, either as a powder or as a thin film, suggesting future applications for soluble conjugated organic polymers in multicomponent photocatalysts for overall water splitting.     

Comparison and confirmation of SNP-bud burst associations in European beech populations in Germany

European beech (Fagus sylvatica L.) is one of the most important forest tree species in Central Europe. Climate change scenarios predict an increase in annual mean temperatures that may cause earlier bud burst in spring, potentially leading to an increased late frost-risk. Despite the ecologic and economic importance of beech, knowledge about the molecular basis of bud burst is still scarce in this species. Here, an association analysis was used to detect SNPs that are significantly associated with beech bud burst. A translocation experiment was established with progenies of six different beech populations from three widely separated regions in Northeast, Central, and Southwest Germany. In total, 600 individuals of the translocation experiment were genotyped using a set of 46 SNPs located in bud burst candidate genes. The association analysis revealed seven SNPs significantly associated with bud burst, each SNP explaining only a few percent of the observed phenotypic variation. Since the same SNP set was used in a previous association analysis with European beech, we were able to compare and confirm significant associations between SNPs and bud burst in distinct beech populations growing in different environments.     

Long-wavelength absorbing and fluorescent chameleon labels for proteins, peptides, and amines

Long-wavelength absorbing labels that change their color and fluorescence upon conjugation to proteins and other biomolecules provide two critical advantages over the wealth of conventional amine-reactive labels. At first, the progress of the labeling reaction can be monitored continuously either visually or by spectrometry without prior purification. Then, the labeled biomolecule can be investigated with red or near-infrared light, which minimizes background interference in biological samples. These unique characteristics are met by a group of long-wavelength absorbing cyanine dyes carrying a reactive chloro substituent for nucleophilic substitution with primary amines, which is accompanied by a color change from green to blue. In addition to this so-called chameleon effect, the dyes display an increase in fluorescence during the labeling reaction. Despite their structural similarity, the reactivity of the dyes differs strongly. The fastest labeling kinetics is observed with dye S 0378 as its five-membered ring affords a stabilizing effect on the intermediate carbocation during an S(N)1-type of nucleophilic substitution. The reaction mechanism of the amine-reactive cyanine dyes provides a blueprint for the design of future long-wavelength absorbing chameleon dyes.     

Platelet-derived Growth Factor-mediated Induction of the Synaptic Plasticity Gene Arc/Arg3.1

Platelet-derived growth factor (PDGF) is a pleiotropic protein with critical roles in both developmental as well as pathogenic processes. In the central nervous system specifically, PDGF is critical for neuronal proliferation and differentiation and has also been implicated as a neuroprotective agent. Whether PDGF also plays a role in synaptic plasticity, however, remains poorly understood. In the present study we demonstrated that in the rat hippocampal neurons PDGF regulated the expression of Arc/Arg3.1 gene that has been implicated in both synapse plasticity and long term potentiation. Relevance of these findings was further confirmed in vivo by injecting mice with intracerebral inoculations of PDGF, which resulted in a rapid induction of Arc in the hippocampus of the injected mice. PDGF induced long term potentiation in rat hippocampal slices, which was abolished by PDGF receptor-tyrosine kinase inhibitor STI-571. We also present evidence that PDGF-mediated induction of Arc/Arg3.1 involved activation of the MAPK/ERK (MEK) pathway. Additionally, induction of Arc/Arg3.1 also involved the upstream release of intracellular calcium stores, an effect that could be blocked by thapsigargin but not by EGTA. Pharmacological approach using inhibitors specific for either MAPK/ERK phosphorylation or calcium release demonstrated that the two pathways converged downstream at a common point involving activation of the immediate early gene Egr-1. Chromatin immunoprecipitation assays demonstrated the binding of Egr-1, but not Egr-3, to the Arc promoter. These findings for the first time, thus, suggest an additional role of PDGF, that of induction of Arc.     

Leishmania exosomes modulate innate and adaptive immune responses through effects on monocytes and dendritic cells

We investigated the properties of leishmania exosomes with respect to influencing innate and adaptive immune responses. Exosomes from Leishmania donovani modulated human monocyte cytokine responses to IFN-γ in a bimodal fashion by promoting IL-10 production and inhibiting that of TNF-α. Moreover, these vesicles were inhibitory with respect to cytokine responses (IL-12p70, TNF-α, and IL-10) by human monocyte-derived dendritic cells. Exosomes from wild-type (WT) L. donovani failed to prime monocyte-derived dendritic cells to drive the differentiation of naive CD4 T cells into IFN-γ-producing Th1 cells. In contrast, vesicles from heat shock protein (HSP)100(-/-) L. donovani showed a gain-of-function and proinflammatory phenotype and promoted the differentiation of naive CD4 lymphocytes into Th1 cells. Proteomic analysis showed that exosomes from WT and HSP100(-/-) leishmania had distinct protein cargo, suggesting that packaging of proteins into exosomes is dependent in part on HSP100. Treatment of C57BL/6 mice with WT L. donovani exosomes prior to challenge with WT organisms exacerbated infection and promoted IL-10 production in the spleen. In contrast, HSP100(-/-) exosomes promoted spleen cell production of IFN-γ and did not adversely affect hepatic parasite burdens. Furthermore, the proparasitic properties of WT exosomes were not species specific because BALB/c mice exposed to Leishmania major exosomes showed increased Th2 polarization and exacerbation of disease in response to infection with L. major. These findings demonstrate that leishmania exosomes are predominantly immunosuppressive. Moreover, to our knowledge, this is the first evidence to suggest that changes in the protein cargo of exosomes may influence the impact of these vesicles on myeloid cell function.     

Regulation of murine placentogenesis by the retroviral genes Syncytin-A,Syncytin-B and Peg10

The murine placenta has a trichorial structure with two multinucleated syncytiotrophoblast (SCT) layers representing a barrier between the maternal and fetal blood system. Genes of endogenous retroviruses and retrotransposon-derived paternally expressed genes (Peg), remnants of past infections and integrations in the genome, have essential functions in placentogenesis. Previous studies showed that the envelope genes Syncytin-A and Syncytin-B were essential for cell–cell fusion of the SCT. The goal of this study was to analyze the temporal localization and expression of nine genes throughout placental development from embryonic day (E)8.5 to E18.5 using in situ-hybridization and absolute RNA-quantification. These included a comparison of previously characterized genes from the labyrinth Syncytin-A, Syncytin-B, Gcm1, the junctional zone PL-1, PL-2, Plf, Tpbpa with two further characterized genes Peg10 and Tpbpb. Syncytin-A and Syncytin-B RNA localized to SCT-I and SCT-II, respectively. Peg10 RNA localized to all extraembryonic tissues, specifically to the parietal and sinusoidal TGC of the labyrinth layer, which is in contact with SCT-I and the maternal blood. All three retroviral/retrotransposon-derived genes showed the highest expression at E16.5, but Peg10 with 188,917.1 molecules/ng cDNA was 208-fold and 106.8-fold higher expressed than Syncytin-A and Syncytin-B, respectively. Tpbpb localized to the junctional zone and showed the highest expression at E16.5 along with PL-2, Plf, Tpbpa, but not PL-1, which decreased in expression at E10.5. To investigate a role of Syncytin-A, Syncytin-B and Peg10 in cell–cell fusion, we established a cell culture system with fractionated primary trophoblasts from murine placentae. Culturing trophoblasts for up to 72 h partly resembled trophoblast development in vivo according to the nine marker genes. Knockdown of Syncytin-A demonstrated a functional regulation of cell–cell fusion, where knockdown of Peg10 showed no involvement in cell fusion. Due to the expression of Peg10 in TGCs, we propose an essential functional role in the fetal–maternal blood system.     

Expression of Multiple Sexual Signals by Fathers and Sons in the East-Mediterranean Barn Swallow: Are Advertising Strategies Heritable?

The level of expression of sexually selected traits is generally determined by genes, environment and their interaction. In species that use multiple sexual signals which may be costly to produce, investing in the expression of one sexual signal may limit the expression of the other, favoring the evolution of a strategy for resource allocation among signals. As a result, even when the expression of sexual signals is condition dependent, the relative level of expression of each signal may be heritable. We tested this hypothesis in the East-Mediterranean barn swallow (Hirundo rustica transitiva), in which males have been shown to express two uncorrelated sexual signals: red-brown ventral coloration, and long tail streamers. We show that variation in both signals may partially be explained by age, as well as by paternal origin (genetic father-son regressions), but that the strongest similarity between fathers and sons is the relative allocation towards one trait or the other (relative expression index), rather than the expression of the traits themselves. These results suggest that the expression of one signal is not independent of the other, and that genetic strategies for resource allocation among sexual signals may be selected for during the evolution of multiple sexual signals.