Fire and herbivory drive fungal and bacterial communities through distinct above- and belowground mechanisms.

Fire and herbivory are important natural disturbances in grassy biomes. Both drivers are likely to influence belowground microbial communities but no studies have unravelled the long-term impact of both fire and herbivory on bacterial and fungal communities. We hypothesized that soil bacterial communities change through disturbance-induced shifts in soil properties (e.g. pH, nutrients) while soil fungal communities change through vegetation modification (biomass and species composition). To test these ideas, we characterised soil physico-chemical properties (pH, acidity, C, N, P and exchangeable cations content, texture, bulk density, moisture), plant species richness and biomass, microbial biomass and bacterial and fungal community composition and diversity (using 16S and ITS rRNA amplicon sequencing, respectively) in six long-term (18 to 70 years) ecological research sites in South African savanna and grassland ecosystems. We found that fire and herbivory regimes profoundly modified soil physico-chemical properties, plant species richness and standing biomass. In all sites, an increase in woody biomass (ranging from 12 to 50%) was observed when natural disturbances were excluded. The intensity and direction of changes in soil properties were highly dependent on the topo-pedo-climatic context. Overall, fire and herbivory shaped bacterial and fungal communities through distinct driving forces: edaphic properties (including Mg, pH, Ca) for bacteria, and vegetation (herbaceous biomass and woody cover) for fungi. Fire and herbivory explained on average 7.5 and 9.8% of the fungal community variability, respectively, compared to 6.0 and 5.6% for bacteria. The relatively small changes in microbial communities due to natural disturbance is in stark contrast to dramatic vegetation and edaphic changes and suggests that soil microbial communities, having evolved with disturbance, are resistant to change. This represents both a buffer to short-term anthropogenic-induced changes and a restoration challenge in the face of long-term changes.

[Laryngeal amyloidosis: a clinical case and review of literature]. / Amyloïdose laryngée: revue de la littérature et cas clinique.

Amyloidosis consists of different forms of systemic or isolated organ lesions characterised by fibrillary protein deposits in extra-cellular tissue. The isolated involvement of the larynx is the most frequent form in the ENT sphere. We present a clinical case of a 67 year-old woman addressed for a sub-acute laryngitis resistant to conservative treatment, and finally diagnosed with laryngeal amyloidosis. We reviewed its physiopathology, the scientific literature as well as the different possibilities of management. Laryngeal amyloidosis is rare. A thorough additional work-up for the research of multifocal or systemic forms is highly recommended. The treatment aims at a minimal invasive endoscopic surgery with functional organ preservation.

Paediatric liver transplanted patients and prevalence of hepatitis E virus.

BACKGROUND: Hepatitis E is an emerging disease in developed countries and is usually asymptomatic, particularly in children. Chronic infection is possible in immunocompromised individuals. In the context of a liver transplant, it can simulate a rejection. In this case, antiviral therapy may be considered, thus highlighting the need to diagnose hepatitis E virus (HEV) infection in this population. OBJECTIVES: Given the lack of data in France, we have studied the the prevalence of antibodies to HEV in the paediatric liver transplant population. STUDY DESIGN: This was a retrospective study, carried out in Lyon between 1st January 2010 and 31 May 2013. HEV serology (anti-HEV IgM &IgG) and HEV PCR were studied in 96 children who had undergone liver transplants (84 isolated liver and 12 combined liver and kidney transplants). RESULTS: Eight patients (8.3%; 62.5% girls; mean age:12.3 years) were HEV seropositive. The mean period since their transplantation was 10 years (range:2-21.8 years). Biliary atresia was the principal indication for transplantation. Seven of these eight children had received liver transplants. There were no differences between the epidemiological and clinical data concerning these patients and the remainder of the study population, particularly with respect to immunosuppression(7/8 tacrolimus; 50% dual immunosuppression). No cases of chronic hepatitis E were found, but 1/8 had chronic cytolysis(EBV&adenovirus infection). In all the patients tested(4/8), seroconversion had occurred after the transplant. There was no significant differences between the age groups in this study. CONCLUSIONS: This study showed that in France, the prevalence of antibodies to HEV in paediatric liver and combined liver and kidney transplant patients is 8.3%, as has been found by other European authors.

An extraordinary case of an intracranial foreign body after a gunshot to the head.

Intermediate targets (IT) can modify the morphology of an entrance wound, the trajectory of the bullet, and contaminate the path with fragments or material from the target. The penetration into the body of big fragments or even of an entire IT is exceptional and only rarely reported in the literature. The interpretation of a gunshot wound after contact of the bullet with IT can sometimes be very tricky as the classical morphology can be missing. The presented case is a rare example of atypical entrance wound and path due to a surprising intermediate target of a gunshot fired against the head.

Factors affecting visualization of postmenopausal ovaries: descriptive study from the multicenter United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS).

OBJECTIVE: Transvaginal sonography (TVS) is core to any ovarian cancer screening strategy. General-population screening involves older postmenopausal women in whom ovarian visualization is difficult because of decreasing ovarian size and lack of follicular activity. We report on factors affecting the visualization of postmenopausal ovaries in the multicenter United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). METHODS: The UKCTOCS is a randomized controlled trial of 202 638 postmenopausal women with 50 639 women in the ultrasound scan arm. TVS is the primary screening modality in the ultrasound scan arm. Age, education, ethnicity, body mass index (BMI), previous pelvic surgery, lifestyle and reproductive factors, and a personal/family history of cancer were assessed for their effects on ovarian visualization at the initial TVS. RESULTS: Between 11 June 2001 and 18 August 2007, 43 867 women underwent TVS. The median age and BMI of the women were 60.6 (interquartile range (IQR), 9.9) years and 25.7 (IQR, 5.8), respectively. The right ovary was visualized in 29 297 (66.8%) and the left ovary was visualized in 28 726 (65.5%). Visualization of ovaries decreased with previous hysterectomy (odds ratio (OR) = 0.534; 95% CI, 0.504-0.567), previous tubal ligation (OR = 0.895; 95% CI, 0.852-0.940), increasing age (OR = 0.953; 95% CI, 0.950-0.956), unilateral oophorectomy (OR = 0.224; 95% CI, 0.186-0.269) and being overweight (OR = 0.918; 95% CI, 0.876-0.962) or obese (OR = 0.715; 95% CI, 0.677-0.755). Increased visualization was observed with a history of infertility (OR = 1.134; 95% CI, 1.005-1.279) and increasing age (in years) at menopause (OR = 1.005; 95% CI, 1.001-1.009). CONCLUSIONS: Several factors affect the visualization of postmenopausal ovaries. Their impact needs to be taken into consideration when developing quality assurance for ovarian ultrasound scanning or comparing study results as their prevalence may differ between populations.

Antidote treatment for cyanide poisoning with hydroxocobalamin causes bright pink discolouration and chemical-analytical interferences.

Here we report the case of a 70-year-old woman who committed suicide by cyanide poisoning. During resuscitation cares, she underwent an antidote treatment by hydroxocobalamin. Postmortem investigations showed marked bright pink discolouration of organs and fluids, and a lethal cyanide blood concentration of 43 mg/L was detected by toxicological investigation. Discolouration of hypostasis and organs has widely been studied in forensic literature. In our case, we interpreted the unusual pink coloration as the result of the presence of hydroxocobalamin. This substance is a known antidote against cyanide poisoning, indicated because of its efficiency and poor adverse effects. However, its main drawback is to interfere with measurements of many routine biochemical parameters. We have tested the potential influence of this molecule in some routine postmortem investigations. The results are discussed.

[Correction of the congenital malformations of the front chest wall by the modelling technique of sternochondroplasty: technique and results on a series of 14 cases]. / Correction des déformations congénitales de la paroi thoracique antérieure par la technique de la sternochondroplastie modelante: technique et résultats à propos d'une série de 14 cas.

In the congenital malformations of the front chest wall showing depression or protrusion, the cardiorespiratory disorders are inconstant and often not linked with the distortion. On the other hand psychoaffective repercussions are major in adolescents and young adults justifying recourse to surgery with morphological and aesthetic aiming. The authors present the technique of modelling sternochondroplasty by raising with osteosynthesis by slide fastener-handle of Martin-Borrelly, applied to the correction of congenital malformation of the front chest wall in young adult, both of protrusion (pectus carinatum), of thoraxes in funnel (pectus excavatum) types or of mixed types (pectus arcuatum). This surgical replanning intervention is carried out by under-mammary way and aims at reestablishing a normal anatomy of the front chest wall. It leads to a genuine wide sternochondrocostal volet, which is stabilised by a specific, multipurpose, adaptable and reliable osteosynthesis equipment. The results obtained on a series of 14 cases are good or excellent in 86% of the cases and stable over time in the absence of major complications. A good cooperation of the patient is essential to obtain a good result in particular via the continuation of musculation exercises after assembly consolidation, possibly associated with remote mammary plastic surgery in the event of hypoplasia or of associated mammary agenesia.

Host manipulation by Ligula intestinalis: a cause or consequence of parasite aggregation?

Previous investigations suggest that the infection of the cyprinid roach, Rutilus rutilus, with the larval plerocercoid forms of the cestode, Ligula intestinalis, creates behavioural and morphological changes in the fish host, potentially of adaptive significance to the parasite in promoting transmission to definitive avian hosts. Here we consider whether these behavioural changes are important in shaping the distribution of parasite individuals across the fish population. An examination of field data illustrates that fish infected with a single parasite were more scarce than expected under the negative binomial distribution, and in many months were more scarce than burdens of two, three or more, leading to a bimodal distribution of worm counts (peaks at 0 and >1). This scarcity of single-larval worm infections could be accounted for a priori by a predominance of multiple infection. However, experimental infections of roach gave no evidence for the establishment of multiple worms, even when the host was challenged with multiple intermediate crustacean hosts, each multiply infected. A second hypothesis assumes that host manipulation following an initial single infection leads to an increased probability of subsequent infection (thus creating a contagious distribution). If manipulated fish are more likely to encounter infected first-intermediate hosts (through microhabitat change, increased ingestion, or both), then host manipulation could act as a powerful cause of aggregation. A number of scenarios based on contagious distribution models of aggregation are explored, contrasted with alternative compound Poisson models, and compared with the empirical data on L. intestinalis aggregation in their roach intermediate hosts. Our results indicate that parasite-induced host manipulation in this system can function simultaneously as both a consequence and a cause of parasite aggregation. This mutual interaction between host manipulation and parasite aggregation points to a set of ecological interactions that are easily missed in most experimental studies of either phenomenon.

Dimerization of the 3'UTR of bicoid mRNA involves a two-step mechanism.

The proper localization of bicoid (bcd) mRNA requires cis-acting signals within its 3' untranslated region (UTR) and trans-acting factors such as Staufen. Dimerization of bcd mRNA through intermolecular base-pairing between two complementary loops of domain III of the 3'UTR was proposed to be important for particle formation in the embryo. The participation in the dimerization process of each domain building the 3'UTR was evaluated by thermodynamic and kinetic analysis of various mutated and truncated RNAs. Although sequence complementarity between the two loops of domain III is required for initiating mRNA dimerization, the initial reversible loop-loop complex is converted rapidly into an almost irreversible complex. This conversion involves parts of RNA outside of domain III that promote initial recognition, and dimerization can be inhibited by sense or antisense oligonucleotides only before conversion has proceeded. Injection of the different bcd RNA variants into living Drosophila embryos shows that all elements that inhibit RNA dimerization in vitro prevent formation of localized particles containing Staufen. Particle formation appeared to be dependent on both mRNA dimerization and other element(s) in domains IV and V. Domain III of bcd mRNA could be substituted by heterologous dimerization motifs of different geometry. The resulting dimers were converted into stable forms, independently of the dimerization module used. Moreover, these chimeric RNAs were competent in forming localized particles and recruiting Staufen. The finding that the dimerization domain of bcd mRNA is interchangeable suggests that dimerization by itself, and not the precise geometry of the intermolecular interactions, is essential for the localization process. This suggests that the stabilizing interactions that are formed during the second step of the dimerization process might represent crucial elements for Staufen recognition and localization.

Selection of genomic target RNAs by iterative screening.

A growing number of proteins are known to exert their regulatory or biological functions via RNA binding. In some cases genetic interactions allow us to infer candidate targets for RNA directed regulation, but in many other cases identification of potential regulatory targets is problematic. We have developed an in vitro biochemical screen, SETIS (SElection of <> Target RNAs by Iterative Screening) that allows screening of a major portion of the genome for identification of potential targets for RNA binding proteins.

Cyanide stimulated dissociation of chloride from the catalytic center of oxidized cytochrome c oxidase.

A comparison of bovine cytochrome c oxidase isolated in the presence and the absence of chloride salts reveals that only enzyme isolated in the presence of chloride salts is a mixture of a complex of oxidized enzyme with chloride (CcO.Cl) and chloride-free enzyme (CcO). Using a spectrophotometric method for chloride determination, it was shown that CcO.Cl contains one chloride ion that is released into the medium by a single turnover or by cyanide binding. Chloride is bound slowly within the heme a(3)-Cu(B) binuclear center of oxidized enzyme in a manner similar to the binding of azide. The pH dependence of the dissociation constant for the formation of the CcO.Cl complex reveals that chloride binding proceeds with the uptake of one proton. With both forms of the enzyme the dependence of the rate of reaction for cyanide binding upon cyanide concentration asymptotes a limiting value indicating the existence of an intermediate. With CcO.Cl this limiting rate is 10(3) higher than the rate of the spontaneous dissociation of chloride from the binuclear center and we propose that the initial step is the coordination of cyanide to Cu(B) and in this intermediate state the rate of dissociation of chloride is substantially enhanced.

Extensive tissue-specific variation of allelic methylation in the Igf2 gene during mouse fetal development: relation to expression and imprinting.

The imprinted Igf2 gene is active only on the paternal allele in most tissues. Its imprinting involves a cis-acting imprinting-control region (ICR) located upstream of the neighboring and maternally expressed H19 gene. It is thought that differential methylation of the parental alleles at the ICR is crucial for parental imprinting of both genes. Differentially methylated regions (DMRs) have also been identified within the Igf2 gene and their differential methylation is thought to be established during early development. To gain further insight into the function of these DMRs, we performed a quantitative analysis of their allelic methylation levels in different tissues during fetal development and the postnatal period in the mouse. Surprisingly, we found that the methylation levels of Igf2 DMRs vary extensively during fetal development, mostly on the expressed paternal allele. In particular, in skeletal muscle, differential allelic methylation in both DMR 1 and DMR 2 occurs only after birth, whereas correct paternal monoallelic expression is always observed, including in the embryonic stages. This suggests that differential methylation in the DMR 1 and DMR 2 of the Igf2 gene is dispensable for its imprinting in skeletal muscle. Furthermore, progressive methylation of the Igf2 paternal allele appears to be correlated with concomitant postnatal down-regulation and silencing of the gene. We discuss possible relations between Igf2 allelic methylation and expression during fetal development.

H19 gene expression is up-regulated exclusively by stabilization of the RNA during muscle cell differentiation.

H19 is a paternally imprinted gene whose expression produces a 2.4 kb RNA in most tissues during development and in mammalian myoblastic cell lines upon differentiation. Deletion of the active maternal allele of H19 and its flanking regions in the mouse leads to biallelic methylation and loss of imprinting of the neighbouring Igf2 gene. The function of H19 RNA remains unknown and, although polysome-associated, the absence of a conserved open reading frame suggests that it does not encode a protein product. We describe a novel post-transcriptional regulation of H19 gene expression which, in spite of this lack of coding capacity, is dependent on translational activity. We show that stabilization of the RNA is solely responsible for its accumulation during in vitro muscle cell differentiation. This conclusion is based on the finding that inhibition of protein synthesis results in a dramatic destabilization of H19 RNA in proliferating mouse C2C12 myoblastic cells but not in differentiated cells, and on run-on experiments which showed that the rate of transcription of H19 RNA remains constant during muscle cell differentiation. This mechanism could also be involved in H19 gene expression during mouse development in addition to its transcriptional activation which we have shown to occur.

Susceptibilidad ante diferentes antimicrobianos en aislamientos de escherichia coli de infecciones urinarias ambulatorias en Santiago / Susceptibility to different antimicrobial agents in isolated escherichia coli of ambulatory urinary infections in Santiago

La resistencia antibiótica es un problema frecuente en aislamientos de E. coli asociados a infecciones del tracto urinario (ITU). Para evaluar la magnitud actual de este problema en Santiago se analizaron los perfiles de resistencia antibiótica de 173 muestras de E. coli provenientes de diferentes pacientes afectados por ITU e identificadas en un laboratorio que atiende exclusivamente pacientes ambulatorios. Los resultados indicaron un alto porcentaje de resistencia ante Ampicilina (45,6 por ciento), Trimetroprim-Sulfametoxazol (STX) (33,5 por ciento) y Cefalotina (20,8 por ciento). La resistencia antibiótica fue infrecuente para los ácidos Nalidíxico y Pipemidico (<10 por ciento cada uno) y marginal ante Ciprofloxacina, Cefuroxima, Gentamicina, y Nitrofurantoina (<3 por ciento cada uno). Todos los aislamientos fueron susceptibles ante Cefotaxima y Amikacina. Un 41 por ciento de los aislamientos fue totalmente susceptible, un 18,9 por ciento multiresistente. Las combinaciones prevalentes de resistencia fueron Ampicilina-STX (15,1 por ciento) y Ampicilina-Cefalotina (7,8 por ciento). Todos los aislamientos resistentes a Ciprofloxacina fueron multiresistentes

pcdr, a novel gene with sexually dimorphic expression in the pigment cells of the Drosophila eye.

We report the molecular cloning and characterization of pcdr (pigment cell dehydrogenase reductase), a Drosophila visual system-specific gene with novel properties of spatial, temporal and sexual regulation. Short chain dehydrogenase/reductases are a family of proteins that catalyze mechanistically conserved dehydrogenase/reductase reactions in a wide range of cells and tissues. These enzymes are required in a variety of reactions ranging from steroid metabolism and prostaglandin synthesis to alcohol detoxification. The Drosophila pcdr gene encodes a new member of this family, displaying 42% amino acid sequence identity to the mammalian prostaglandin dehydrogenase. pcdr expression is restricted to the visual system with very high levels found in the pigment cells. Interestingly, expression of pcdr mRNA is sexually dimorphic with males showing higher levels of expression than females. This sexual dimorphism is under the control of the sex differentiation cascade as transformer and transformer 2 mutations shift females to a male-like level of expression. Finally, we demonstrate that a region of 335 nucleotides including sequences upstream and just downstream of the transcription start is sufficient to reproduce the normal expression pattern.

Molecular cloning and bacterial expression of a general odorant-binding protein from the cabbage armyworm Mamestra brassicae.

A cDNA clone encoding a general odorant-binding protein (GOBP2) was isolated from antennal RNA of Mamestra brassicae by reverse transcription-PCR (RT-PCR) and RACE-PCR. The cDNA encoding the GOBP2 was further used for bacterial expression. Most of the recombinant GOBP2 (>90%) was found to be insoluble. Purification under denaturing conditions consisted of solubilisation of inclusion bodies, affinity chromatography, refolding and gel filtration. The refolded rGOBP2 was cross-reactive with a serum raised against the GOBP2 of the Lepidoptera Antheraea polyphemus. The purified refolded rGOBP2 was further characterised by native PAGE, IEF, N-terminal sequencing, and two-dimensional NMR. A functional characterisation of the rGOBP2 was carried out by testing its ability to bind pheromone compounds. The yields of production and purification fulfil the requirements of structural studies.

DNA topoisomerase I: customs officer at the border between DNA and RNA worlds?

DNA topoisomerase I is required for the normal development of multicellular organisms, probably because it plays a role in controlling gene activity, in addition to its function in relieving tortional stress during DNA replication and transcription. The discovery of DNA topoisomerase I as a specific kinase that phosphorylates serine-arginine rich (SR) splicing factors may provide new insights into their precise function in regulating gene expression. It is clear that the splicing factors phosphorylated by DNA topoisomerase I can modulate gene expression by changing the splicing pattern of structural genes. Studies of the splicing mechanism suggest that the phosphorylation of serine residues of SR proteins contribute to their activity. As this phosphorylation can be accomplished by several kinases, it remains to be determined whether phosphorylation by DNA topoisomerase I protein kinase is the limiting step in regulating this process. The availability of specific inhibitors of DNA topoisomerase I, structurally related to the alkaloid camptothecin, have made it possible to address this question experimentally. These inhibitors, which hold great promise as antineoplastic drugs, lead to specific inhibition of SR protein phosphorylation in cultured cells. This observation will hopefully lead to improved understanding of the mechanism by which these drugs act at cellular level.

The expression of E.coli threonyl-tRNA synthetase is regulated at the translational level by symmetrical operator-repressor interactions.

Threonyl-tRNA synthetase from Escherichia coli represses the translation of its own mRNA by binding to the operator region located upstream from the ribosome binding site. The operator contains two stemloop structures which interact specifically with the homodimeric enzyme. Here, we provide in vitro and in vivo evidence that these two stem-loop structures are recognized by the enzyme in an analogous way and mimic the anticodon arm of E.coli tRNA(Thr). Determination of the stoichiometry of the different RNA-threonyl-tRNA synthetase complexes reveals that two tRNA(Thr) molecules bind to the enzyme whereas only one thrS operator interacts with the homodimeric enzyme. A model is presented in which the two anticodon-like domains of the operator bind symmetrically to the two tRNA(Thr) anticodon recognition sites (one per subunit) of the dimeric threonyl-tRNA synthetase. Although symmetrical operator-repressor interactions in transcriptional control are widespread, this report stresses the importance of such interactions in translational regulation of gene expression.