Conséquences démographiques du sida en Abidjan : 1986-1992

Les statistiques de l'état civil et des formations sanitaires sont notoirement peu utilisées en Afrique pour étudier les tendances de la mortalité. L'étude d'Abidjan montre que c'est une situation très regrettable, car ces statistiques peuvent fournir de précieux renseignements sur l'état sanitaire de la population. Dans le cas présent, l'analyse fine des tendances de la mortalité, couplée avec l'analyse des causes de décès dans les hôpitaux, révèle assez précisément les conséquences démographiques du sida dans la capitale de la Côte d'Ivoire, malgré l'imperfection des données. Les estimations indiquent que près de 25 000 personnes seraient décédées du sida entre 1986 et 1992, les sept premières années de l'épidémie, ce qui confirme qu'Abidjan est une des villes les plus touchées au monde par cette troublante épidémie. Ce sont surtout les jeunes de sexe masculin qui ont été les plus touchés, dans toutes les couches de la société. Un modèle a permis de reconstruire la dynamique de l'épidémie, qui montre que le premier pic des infections se serait produit vers 1987. On peut s'attendre à une moyenne d'environ 7 000 cas de sida par an dans la ville jusqu'à l'an 2000, ce qui aura des conséquences importantes sur l'utilisation des infrastructures hospitalières. L'importance numérique de ces estimations souligne l'urgence de renforcer la lutte contre l'épidémie de sida en Côte d'Ivoire et dans le monde. (Résumé d'auteur

Relationships between physiological characteristics and trace metal body burdens of banded garden spiders Argiope trifasciata (Araneae, Araneidae)

Banded garden spiders (Argiope trifasciata) were collected at the Ballona Wetlands, a metal contaminated salt marsh. The relationship between spider body size and individual metal loads was investigated. Biochemical markers were identified in spider fecal material and found to correlate to body metal levels. Body metal dry weight concentrations of Cd, Cr, Cu, Zn and total metals in female A. trifasciata exhibited distinct patterns of spatial and annual variation during 2006 and 2007. Spider body size was homogeneous across sites in both years, while increased Cd and Cr concentrations were sometimes associated with a reduction in spider size, though the influence of Cr was quite minor. Spiders with higher body Cu levels showed a reduction in peak area for hypoxanthine and an un-identified component in fecal material chromatograms. Spatial and annual differences in metal bioaccumulation are likely mediated by variation in site-specific environmental parameters and rainfall, while the negative relationships between body size and metal levels are presumably a consequence of a spider\u27s expenditure of energy for metal tolerance mechanisms vs. foraging and growth. Finally, correlating body metal levels with excreta products constitutes a novel method to non-invasively predict metal levels in spiders

Microbial community drivers of PK/NRP gene diversity in selected global soils

Background The emergence of antibiotic-resistant pathogens has created an urgent need for novel antimicrobial treatments. Advances in next-generation sequencing have opened new frontiers for discovery programmes for natural products allowing the exploitation of a larger fraction of the microbial community. Polyketide (PK) and non-ribosomal pepetide (NRP) natural products have been reported to be related to compounds with antimicrobial and anticancer activities. We report here a new culture-independent approach to explore bacterial biosynthetic diversity and determine bacterial phyla in the microbial community associated with PK and NRP diversity in selected soils. Results Through amplicon sequencing, we explored the microbial diversity (16S rRNA gene) of 13 soils from Antarctica, Africa, Europe and a Caribbean island and correlated this with the amplicon diversity of the adenylation (A) and ketosynthase (KS) domains within functional genes coding for non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), which are involved in the production of NRP and PK, respectively. Mantel and Procrustes correlation analyses with microbial taxonomic data identified not only the well-studied phyla Actinobacteria and Proteobacteria, but also, interestingly, the less biotechnologically exploited phyla Verrucomicrobia and Bacteroidetes, as potential sources harbouring diverse A and KS domains. Some soils, notably that from Antarctica, provided evidence of endemic diversity, whilst others, such as those from Europe, clustered together. In particular, the majority of the domain reads from Antarctica remained unmatched to known sequences suggesting they could encode enzymes for potentially novel PK and NRP. Conclusions The approach presented here highlights potential sources of metabolic novelty in the environment which will be a useful precursor to metagenomic biosynthetic gene cluster mining for PKs and NRPs which could provide leads for new antimicrobial metabolites

Primary and secondary defences of squid to cruising and ambush fish predators : variable tactics and their survival value

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Animal Behaviour 81 (2011): 585-594, doi:10.1016/j.anbehav.2010.12.002.Longfin squid (Loligo pealeii) were exposed to two predators, bluefish (Pomatomus saltatrix) and summer flounder (Paralichthys dentatus), representing cruising and ambush foraging tactics, respectively. During 35 trials, 86 predator–prey interactions were evaluated between bluefish and squid, and in 29 trials, 92 interactions were assessed between flounder and squid. With bluefish, squid predominantly used stay tactics (68.6%, 59/86) as initial responses. The most common stay response was to drop to the bottom, while showing a disruptive body pattern, and remain motionless. In 37.0% (34/92) of interactions with flounder, squid did not detect predators camouflaging on the bottom and showed no reaction prior to being attacked. Squid that did react, used flee tactics more often as initial responses (43.5%, 40/92), including flight with or without inking. When all defence behaviours were considered concurrently, flight was identified as the strongest predictor of squid survival during interactions with each predator. Squid that used flight at any time during an attack sequence had high probabilities of survival with bluefish (65%, 20/31) and flounder (51%, 18/35). The most important deimatic/protean behaviour used by squid was inking. Inking caused bluefish to startle (deimatic) and abandon attacks (probability of survival = 61%, 11/18) and caused flounder to misdirect (protean) attacks towards ink plumes rather than towards squid (probability of survival = 56%, 14/25). These are the first published laboratory experiments to evaluate the survival value of antipredator behaviours in a cephalopod. Results demonstrate that squid vary their defence tactics in response to different predators and that the effectiveness of antipredator behaviours is contingent upon the behavioural characteristics of the predator encountered.This study was funded by the Woods Hole Oceanographic Institution Sea Grant Program, the Massachusetts Marine Fisheries Institute, the University of Massachusetts and the Five College Coastal and Marine Sciences Program. R. T. Hanlon acknowledges partial support from ONR grant N000140610202 and the Sholley Foundation

Characterisation of the microbiome along the gastrointestinal tract of growing turkeys

The turkey microbiome is largely understudied, despite its relationship with bird health and growth, and the prevalence of human pathogens such as Campylobacter spp. In this study we investigated the microbiome within the small intestine (SI), caeca (C), large intestine (LI) and cloaca (CL) of turkeys at 6, 10 and 16 weeks of age. Eight turkeys were dissected within each age category and the contents of the SI, C, LI and CL were harvested. 16S rDNA based QPCR was performed on all samples and samples for the 4 locations within 3 birds/age group were sequenced using ion torrent-based sequencing of the 16S rDNA. Sequencing data showed on a genus level, an abundance of Lactobacillus, Streptococcus and Clostridium XI (38.2, 28.1 and 13.0% respectively) irrespective of location and age. The caeca exhibited the greatest microbiome diversity throughout the development of the turkey. PICRUSt data predicted an array of bacterial function, with most differences being apparent in the caeca of the turkeys as they matured. QPCR revealed that the caeca within 10 week old birds, contained the most Campylobacter spp. Understanding the microbial ecology of the turkey gastrointestinal tract is essential in terms of understanding production efficiency and in order to develop novel strategies for targeting Campylobacter spppublishersversionPeer reviewe

Kinetic and structural characterization of NUDT15 and NUDT18 as catalysts of isoprene pyrophosphate hydrolysis

Isoprene pyrophosphates play a crucial role in the synthesis of a diverse array of essential nonsterol and sterol biomolecules and serve as substrates for posttranslational isoprenylation of proteins, enabling specific anchoring to cellular membranes. Hydrolysis of isoprene pyrophosphates would be a means to modulate their levels, downstream products, and protein isoprenylation. While NUDIX hydrolases from plants have been described to catalyze the hydrolysis of isoprene pyrophosphates, homologous enzymes with this function in animals have not yet been reported. In this study, we screened an extensive panel of human NUDIX hydrolases for activity in hydrolyzing isoprene pyrophosphates. We found that human nucleotide triphosphate diphosphatase NUDT15 and 8-oxo-dGDP phosphatase NUDT18 efficiently catalyze the hydrolysis of several physiologically relevant isoprene pyrophosphates. Notably, we demonstrate that geranyl pyrophosphate is an excellent substrate for NUDT18, with a catalytic efficiency of 2.1 × 105 m−1·s−1, thus making it the best substrate identified for NUDT18 to date. Similarly, geranyl pyrophosphate proved to be the best isoprene pyrophosphate substrate for NUDT15, with a catalytic efficiency of 4.0 × 104 M−1·s−1. LC–MS analysis of NUDT15 and NUDT18 catalyzed isoprene pyrophosphate hydrolysis revealed the generation of the corresponding monophosphates and inorganic phosphate. Furthermore, we solved the crystal structure of NUDT15 in complex with the hydrolysis product geranyl phosphate at a resolution of 1.70 Å. This structure revealed that the active site nicely accommodates the hydrophobic isoprenoid moiety and helped identify key binding residues. Our findings imply that isoprene pyrophosphates are endogenous substrates of NUDT15 and NUDT18, suggesting they are involved in animal isoprene pyrophosphate metabolism

Life Expectancy and Education: Evidence from the Cardiovascular Revolution

This paper exploits the unexpected decline of deaths from cardiovascular diseases since the 1970s as a large positive health shock that affected predominantly old-age mortality; i.e., the fourth stage of the epidemiological transition. Using a differences-in-differences estimation strategy, we find that U.S. states with higher levels of cardiovascular-disease mortality prior the 1970s experienced greater increases in adultlife expectancy and higher education enrollment. Our estimates suggest that the cardiovascular revolution caused an increase in life expectancy of 1.5 years and an increase in education enrollment of 9 percentage points, i.e. 52 percent of the observed increase from 1960 to 2000

A Genome-Wide Collection of Mos1 Transposon Insertion Mutants for the C. elegans Research Community

Methods that use homologous recombination to engineer the genome of C. elegans commonly use strains carrying specific insertions of the heterologous transposon Mos1. A large collection of known Mos1 insertion alleles would therefore be of general interest to the C. elegans research community. We describe here the optimization of a semi-automated methodology for the construction of a substantial collection of Mos1 insertion mutant strains. At peak production, more than 5,000 strains were generated per month. These strains were then subject to molecular analysis, and more than 13,300 Mos1 insertions characterized. In addition to targeting directly more than 4,700 genes, these alleles represent the potential starting point for the engineered deletion of essentially all C. elegans genes and the modification of more than 40% of them. This collection of mutants, generated under the auspices of the European NEMAGENETAG consortium, is publicly available and represents an important research resource

Sex differential in mortality trends of old-aged Danes: a nation wide study of age, period and cohort effects

Objective Over the last half century the mortality rates in Denmark for females above age 80 have declined dramatically whereas the decline for males have been modest, resulting in a change in sex-ratio for centenarians from 2 to 5. Here we investigate whether this mortality pattern is mainly explained by period effects, cohort effects or both. This can provide clues for where to search for causes behind the changes in sex differential in mortality seen in many Western countries during the last decades. Methods Age-period-cohort study of mortality for all Danish women and men aged 79–98 during the period 1949–2006. Outcome measures Relative risks for deaths and second order differences for exploration of the nonlinear variation. Results Both the overall trends in mortality differences and the fluctuations in mortality for both men and women were better explained by period effects than by cohort effects. The observed rates were better described by the age, period and cohort model than by other models. Conclusions Our results suggest that causes for both the overall increased difference in mortality and the short term fluctuations in mortality rates are primarily to be found in the period dimension. Cohort effects on the mortality of the oldest Danish women and men played a significant but minor role compared to period effects

Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures

Topological insulators are characterized by a nontrivial band topology driven by the spin-orbit coupling. To fully explore the fundamental science and application of topological insulators, material realization is indispensable. Here we predict, based on tight-binding modeling and first-principles calculations, that bilayers of perovskite-type transition-metal oxides grown along the [111] crystallographic axis are potential candidates for two-dimensional topological insulators. The topological band structure of these materials can be fine-tuned by changing dopant ions, substrates, and external gate voltages. We predict that LaAuO$_3$ bilayers have a topologically-nontrivial energy gap of about 0.15 eV, which is sufficiently large to realize the quantum spin-Hall effect at room temperature. Intriguing phenomena, such as fractional quantum Hall effect, associated with the nearly-flat topologically-nontrivial bands found in $e_g$ systems are also discussed.Comment: Main text 11 pages with 4 figures and 1 table. Supplementary materials 4 pages with 2 figure