The Geodia cydonium galectin exhibits prototype and chimera-type characteristics and a unique sequence polymorphism within its carbohydrate recognition domain

The ancestral galectin from the sponge Geodia cydonium (GCG) is classified on a structural basis to the prototype subfamily, whereas its carbohydrate-binding specificity is related to that of the mammalian chimera-type galectin-3. This dual coordination reveals GCG as a potential precursor of the later evolved galectin subfamilies, which is reflected in the primary structure of the protein. This study provides evidence that GCG is the LECT1 gene product, while neither a previously described LECT2 gene nor a functional LECT2 gene product was found in the specimen under investigation. The electrophoretically separated protein isomers with apparent molecular masses of 13, 15, and 16 kDa correspond to variants of the LECT1 protein-exhibiting peptide sequence polymorphisms that concern critical positions of the carbohydrate recognition domain (13 kDa: Leu51, Asn55, His130, Gly137; 15 kDa: Ser51, Asn55, Asn130, Gly137; 16 kDa: Ser51, Tyr55, Asn130, Glu137). Four residues, highly conserved in the galectin family, are substituted. None of the residues claimed to be involved in interactions with GalNAcalpha1-3 moieties at an extended binding subsite of galectin-3 was identified in the corresponding positions of GCG. Apparently, the substitutions do not confer distinct binding characteristics to the GCG variants as evidenced by binding studies with a recombinantly expressed 15-kDa isoform. The natural isoforms as well as the recombinant 15-kDa isoform oligomerize by the formation of non-covalent heteromeric or homomeric complexes. A phosphorylation of the galectin was confirmed neither by mass spectrometry nor by alkaline phosphatase treatment combined with isoelectric focusing.     

Dynamics of the formin for3p in actin cable assembly

BACKGROUND: Formins are a conserved family of actin nucleators responsible for the assembly of diverse actin structures such as cytokinetic rings and filopodia. In the fission yeast Schizosaccharomyces pombe, the formin for3p is necessary for the formation of actin cables, which are bundles of short parallel actin filaments that regulate cell polarity. These filaments are largely organized with their barbed ends facing the cell tip, where for3p is thought to function in their assembly. RESULTS: Here, using a functional for3p-3GFP fusion expressed at endogenous levels, we find that for3p localizes to small dots that appear transiently at cell tips and then move away on actin cables at a rate of 0.3 microm/s. These movements were dependent on the continuous assembly of actin in cables, on the ability of for3p to bind actin within its FH2 domain, and on profilin and bud6p, two formin binding proteins that promote formin activity. Bud6p transiently colocalizes with for3p at the cell tip and stays behind at the cell tip when for3p detaches. CONCLUSIONS: These findings suggest a new model for actin cable assembly: a for3p particle is activated and promotes the assembly of a short actin filament at the cell tip for only seconds. For3p and the actin filament may then be released from the cell tip and carried passively into the cell interior by retrograde flow of actin filaments in the cable. These studies reveal a complex and dynamic cycle of formin regulation and actin cable assembly in vivo.     

Molecular and phenotypic divergence in the bluethroat (Luscinia svecica) subspecies complex

Subspecies complexes may provide valuable insights into the early stages of the speciation process. The bluethroat (Luscinia svecica) consists of many morphologically distinct subspecies that differ most strikingly in the ornamental colour pattern of the male throat. We investigated the genetic and phenotypic differentiation in this subspecies complex, using (i) microsatellite genotyping (11 loci) of a sample of 364 individuals from bluethroat populations in Europe and Asia, and (ii) spectrometric and morphological measurements of a sample of 131 museum skin specimens. Population genetic analyses, based on microsatellite allele frequency variation, revealed a slight but significant overall population differentiation (F(ST) = 0.042). There was a well-differentiated southern group of subspecies with white or no throat spots and a less-differentiated northern group of chestnut-spotted populations. Phylogenetic analyses indicated that the southern all-blue and white-spotted forms are ancestral to the chestnut-spotted subspecies. In addition to the qualitative variation in throat plumage pattern already described in the literature, we found significant quantitative variation among subspecies in hue, chroma and brightness of the ultraviolet (UV)/blue throat coloration, and this variation seemed to be unrelated to the phylogenetic distance between subspecies.     

Intracellular trafficking of interleukin-1 receptor I requires Tollip

Interleukin-1 receptor (IL-1RI) is a master regulator of inflammation and innate immunity. When triggered by IL-1beta, IL-1RI aggregates with IL-1R-associated protein (IL-1RAcP) and forms a membrane proximal signalosome that potently activates downstream signaling cascades. IL-1beta also rapidly triggers endocytosis of IL-1RI. Although internalization of IL-1RI significantly impacts signaling, very little is known about trafficking of IL-1RI and therefore about precisely how endocytosis modulates the overall cellular response to IL-1beta. Upon internalization, activated receptors are often sorted through endosomes and delivered to lysosomes for degradation. This is a highly regulated process that requires ubiquitination of cargo proteins as well as protein-sorting complexes that specifically recognize ubiquitinated cargo. Here, we show that IL-1beta induces ubiquitination of IL-1RI and that via these attached ubiquitin groups, IL-1RI interacts with the ubiquitin-binding protein Tollip. By using an assay to follow trafficking of IL-1RI from the cell surface to late endosomes and lysosomes, we demonstrate that Tollip is required for sorting of IL-1RI at late endosomes. In Tollip-deficient cells and cells expressing only mutated Tollip (incapable of binding IL-1RI and ubiquitin), IL-1RI accumulates on late endosomes and is not efficiently degraded. Furthermore, we show that IL-1RI interacts with Tom1, an ubiquitin-, clathrin-, and Tollip-binding protein, and that Tom1 knockdown also results in the accumulation of IL-1RI at late endosomes. Our findings suggest that Tollip functions as an endosomal adaptor linking IL-1RI, via Tom1, to the endosomal degradation machinery.     

The role of domain redundancy in genetic robustness against null mutations

A key question in molecular genetics is why severe gene mutations often do not result in a detectable abnormal phenotype. Alternative networks are known to be a gene compensation mechanism. Gene redundancy, i.e. the presence of a duplicate gene (or paralog) elsewhere in the genome, also underpins many cases of gene dispensability. Here, we investigated the role of partial duplicate genes on dispensability, where a partial duplicate is defined as a gene that has no paralog but which codes for a protein made of domains, each of which belongs to at least another protein. The rationale behind this investigation is that, as a partial duplicate codes for a domain redundant protein, we hypothesised that its deletion might have a less severe phenotypic effect than the deletion of other genes. This prompted us to (re)address the topic of gene dispensability by focusing on domain redundancy rather than on gene redundancy. Using fitness data of single-gene deletion mutants of Saccharomyces cerevisiae, we will show that domain redundancy is a compensation mechanism, the strength of which is lower than that of gene redundancy. Finally, we shall discuss the molecular basis of this new compensation mechanism.     

Overstimulation of PrPC signaling pathways by prion peptide 106-126 causes oxidative injury of bioaminergic neuronal cells

Transmissible spongiform encephalopathies, also called prion diseases, are characterized by neuronal loss linked to the accumulation of PrP(Sc), a pathologic variant of the cellular prion protein (PrP(C)). Although the molecular and cellular bases of PrP(Sc)-induced neuropathogenesis are not yet fully understood, increasing evidence supports the view that PrP(Sc) accumulation interferes with PrP(C) normal function(s) in neurons. In the present work, we exploit the properties of PrP-(106-126), a synthetic peptide encompassing residues 106-126 of PrP, to investigate into the mechanisms sustaining prion-associated neuronal damage. This peptide shares many physicochemical properties with PrP(Sc) and is neurotoxic in vitro and in vivo. We examined the impact of PrP-(106-126) exposure on 1C11 neuroepithelial cells, their neuronal progenies, and GT1-7 hypothalamic cells. This peptide triggers reactive oxygen species overflow, mitogen-activated protein kinase (ERK1/2), and SAPK (p38 and JNK1/2) sustained activation, and apoptotic signals in 1C11-derived serotonergic and noradrenergic neuronal cells, while having no effect on 1C11 precursor and GT1-7 cells. The neurotoxic action of PrP-(106-126) relies on cell surface expression of PrP(C), recruitment of a PrP(C)-Caveolin-Fyn signaling platform, and overstimulation of NADPH-oxidase activity. Altogether, these findings provide actual evidence that PrP-(106-126)-induced neuronal injury is caused by an amplification of PrP(C)-associated signaling responses, which notably promotes oxidative stress conditions. Distorsion of PrP(C) signaling in neuronal cells could hence represent a causal event in transmissible spongiform encephalopathy pathogenesis.     

Curcumin modulates drug metabolizing enzymes in the female Swiss Webster mouse

Curcumin, the yellow pigment found in turmeric, exhibits potent chemopreventative properties in both in vivo and in vitro cancer models. We hypothesized that this effect may occur via curcumin-mediated changes in enzymes involved in both carcinogen bioactivation and estrogen metabolism. Female Swiss Webster mice were treated with either curcumin (200 mg/kg or 400 mg/kg, p.o.) or vehicle control for 1 or 2 weeks. The results demonstrated that curcumin had no effect on the catalytic activities of ovarian aromatase, hepatic catechol-O-methyltransferase or hepatic UDP-glucuronosyltransferase. However, both doses of curcumin caused a 25% decrease in CYP1A catalytic activity, but not polypeptide levels, following 2 weeks of treatment. Additionally, following 2 weeks of curcumin at 400 mg/kg, there was a 20% decrease in the catalytic activity and a 28% decrease in polypeptide levels of CYP3A. While 2 weeks of curcumin treatment (400 mg/kg) caused a 20% increase in glutathione S-transferase activity, there was no parallel increase in hepatic stores of the co-factor glutathione. In conclusion small changes in CYP1A, CYP3A and GST following long term treatment (2 weeks) suggest that the combination of all three metabolic pathways may play a small role in curcumin's chemopreventative action.     

French Experience of 2009 A/H1N1v Influenza in Pregnant Women

Background

The first reports on the pandemic influenza 2009 A/H1N1v from the USA, Mexico, and Australia indicated that this disease was associated with a high mortality in pregnant women. The aim of this study was to describe and compare the characteristics of severe critically ill and non-severe pregnant women with 2009 A/H1N1v-related illness in France.

Methodology/Principal Findings

A national registry was created to screen pregnant women with laboratory-confirmed 2009 A/H1N1v influenza. Three hundred and fifteen patients from 46 French hospitals were included: 40 patients were admitted to intensive care units (severe outcomes), 111 were hospitalized in obstetric or medical wards (moderate outcomes), and 164 were outpatients (mild outcomes). The 2009 A/H1N1v influenza illness occurred during all pregnancy trimesters, but most women (54%), notably the severe patients (70%), were in the third trimester. Among the severe patients, twenty (50%) underwent mechanical ventilation, and eleven (28%) were treated with extracorporeal membrane oxygenation. Three women died from A/H1N1v influenza. We found a strong association between the development of a severe outcome and both co-existing illnesses (adjusted odds ratio [OR], 5.1; 95% confidence interval [CI], 2.2–11.8) and a delay in oseltamivir treatment after the onset of symptoms (>3 or 5 days) (adjusted OR, 4.8; 95% CI, 1.9–12.1 and 61.2, 95% CI; 14.4–261.3, respectively). Among the 140 deliveries after 22 weeks of gestation known to date, 19 neonates (14%) were admitted to a neonatal intensive care unit, mainly for preterm delivery, and two neonates died. None of these neonates developed 2009 A/H1N1v infection.

Conclusions

This series confirms the high incidence of complications in pregnant women infected with pandemic A/H1N1v observed in other countries but depicts a lower overall maternal and neonatal mortality and morbidity than indicated in the USA or Australia. Moreover, our data demonstrate the benefit of early oseltamivir treatment in this specific population.     

Nodular Worm Infection in Wild Chimpanzees in Western Uganda: A Risk for Human Health?

This study focused on Oeosophagostomum sp., and more especially on O. bifurcum, as a parasite that can be lethal to humans and is widespread among humans and monkeys in endemic regions, but has not yet been documented in apes. Its epidemiology and the role played by non-human primates in its transmission are still poorly understood. O. stephanostomum was the only species diagnosed so far in chimpanzees. Until recently, O. bifurcum was assumed to have a high zoonotic potential, but recent findings tend to demonstrate that O. bifurcum of non-human primates and humans might be genetically distinct. As the closest relative to human beings, and a species living in spatial proximity to humans in the field site studied, Pan troglodytes is thus an interesting host to investigate. Recently, a role for chimpanzees in the emergence of HIV and malaria in humans has been documented. In the framework of our long-term health monitoring of wild chimpanzees from Kibale National Park in Western Uganda, we analysed 311 samples of faeces. Coproscopy revealed that high-ranking males are more infected than other individuals. These chimpanzees are also the more frequent crop-raiders. Results from PCR assays conducted on larvae and dried faeces also revealed that O. stephanostomum as well as O. bifurcum are infecting chimpanzees, both species co-existing in the same individuals. Because contacts between humans and great apes are increasing with ecotourism and forest fragmentation in areas of high population density, this paper emphasizes that the presence of potential zoonotic parasites should be viewed as a major concern for public health. Investigations of the parasite status of people living around the park or working inside as well as sympatric non-human primates should be planned, and further research might reveal this as a promising aspect of efforts to reinforce measures against crop-raiding.