Déterminisme des Coassements des Anoures de la ferme piscicole du Parc National du Banco (Côte d\'Ivoire)

Les facteurs déterminant les activités de coassements des anoures de la ferme piscicole du Parc National du Banco ont été étudiés. Une prospection acoustique basée sur l\'enregistrement standardisé des chants des grenouilles, a permis d\'inventorier, pendant quatre cycles nycthéméraux, 14 espèces réparties en 8 genres et 4 familles. La famille des Hyperoliidae avec 7 espèces est la plus diversifiée. Parmi les espèces recensées, une seule (Phrynobatrachus accraensis), a son pic d\'activité à 6 heures. Son rythme d\'activité de chants est influencé par la température de l\'air et l\'intensité lumineuse. Les Bufonidae, Hyperoliidae et Ranidae constituent une communauté aux moeurs nocturnes dont les pics de coassements se situent entre 21 heures et 24 heures. L\'humidité relative de l\'air conditionne leurs comportements. Par ailleurs, la majorité des espèces a une forte activité de coassement en saison de pluies. Nos résultats qui sont parmi les premiers concernant les communautés d\'Anoures du Parc National du Banco, permettront d\'élaborer une stratégie pour leur échantillonnage et leur protection.The factors determining the calling activities of anuran community in the Banco National Park fish farm have been studied. The standard acoustic encounter survey based on listening calling males permitted to inventory 14 species, 8 genera and 4 families, during four circadian cycles. The family of Hyperoliidae is diversified the most (7 species). Only one diurnal species (Phrynobatrachus accraensis) was observed, with a peak of activity at 6 hours. Its daily calling activity is influenced by the temperature of the air and the light intensity. The Bufonidae, Hyperoliidae and Ranidae families are nocturnal community. Their peaks of activity varied between 21 hours and 24 hours. The relative humidity of the air determined the behavior of these families. In addition, most of the species have a strong calling activity during the rainy season. Our results should permit to elaborate a standard method for amphibians survey in the Park. Keywords: Calling activity, Temporal variation, Amphibian, Banco National Park, West Africa.Sciences & Nature Vol. 5 (1) 2008: pp. 71-7

Expression and cytosolic assembly of the S-layer fusion protein mSbsC-EGFP in eukaryotic cells

BACKGROUND: Native as well as recombinant bacterial cell surface layer (S-layer) protein of Geobacillus (G.) stearothermophilus ATCC 12980 assembles to supramolecular structures with an oblique symmetry. Upon expression in E. coli, S-layer self assembly products are formed in the cytosol. We tested the expression and assembly of a fusion protein, consisting of the mature part (aa 31–1099) of the S-layer protein and EGFP (enhanced green fluorescent protein), in eukaryotic host cells, the yeast Saccharomyces cerevisiae and human HeLa cells. RESULTS: Upon expression in E. coli the recombinant mSbsC-EGFP fusion protein was recovered from the insoluble fraction. After denaturation by Guanidine (Gua)-HCl treatment and subsequent dialysis the fusion protein assembled in solution and yielded green fluorescent cylindric structures with regular symmetry comparable to that of the authentic SbsC. For expression in the eukaryotic host Saccharomyces (S.) cerevisiae mSbsC-EGFP was cloned in a multi-copy expression vector bearing the strong constitutive GPD1 (glyceraldehyde-3-phosophate-dehydrogenase) promoter. The respective yeast transfomants were only slightly impaired in growth and exhibited a needle-like green fluorescent pattern. Transmission electron microscopy (TEM) studies revealed the presence of closely packed cylindrical structures in the cytosol with regular symmetry comparable to those obtained after in vitro recrystallization. Similar structures are observed in HeLa cells expressing mSbsC-EGFP from the Cytomegalovirus (CMV IE) promoter. CONCLUSION: The mSbsC-EGFP fusion protein is stably expressed both in the yeast, Saccharomyces cerevisiae, and in HeLa cells. Recombinant mSbsC-EGFP combines properties of both fusion partners: it assembles both in vitro and in vivo to cylindrical structures that show an intensive green fluorescence. Fusion of proteins to S-layer proteins may be a useful tool for high level expression in yeast and HeLa cells of otherwise instable proteins in their native conformation. In addition the self assembly properties of the fusion proteins allow their simple purification. Moreover the binding properties of the S-layer part can be used to immobilize the fusion proteins to various surfaces. Arrays of highly ordered and densely structured proteins either immobilized on surfaces or within living cells may be advantageous over the respective soluble variants with respect to stability and their potential interference with cellular metabolism

Carbon-nanoparticle-triggered acute lung inflammation and its resolution are not altered in PPARγ-defective (P465L) mice.

BACKGROUND: The alveolar macrophage (AM) - first line of innate immune defence against pathogens and environmental irritants - constitutively expresses peroxisome-proliferator activated receptor γ (PPARγ). PPARγ ligand-induced activation keeps the AM quiescent, and thereby contributes to combat invaders and resolve inflammation by augmenting the phagocytosis of apoptotic neutrophils and inhibiting an excessive expression of inflammatory genes. Because of these presumed anti-inflammatory functions of PPARγ we tested the hypothesis, whether reduced functional receptor availability in mutant mice resulted in increased cellular and molecular inflammatory response during acute inflammation and/or in an impairment of its resolution. METHODS: To address this hypothesis we examined the effects of a carbon-nanoparticle (CNP) lung challenge, as surrogate for non-infectious environmental irritants, in a murine model carrying a dominant-negative point mutation in the ligand-binding domain of PPARγ (P465L/wt). Animals were instilled intratracheally with Printex 90 CNPs and bronchoalveolar lavage (BAL) was gained 24 h or 72 h after instillation to investigate its cellular and protein composition. RESULTS: Higher BAL cell numbers - due to higher macrophage counts - were found in mutants irrespective of treatment. Neutrophil numbers in contrast were slightly lower in mutants. Intratracheal CNP instillation resulted in a profound recruitment of inflammatory neutrophils into the alveolus, but genotype related differences at acute inflammation (24 h) and resolution (72 h) were not observed. There were no signs for increased alveolar-capillary membrane damage or necrotic cell death in mutants as determined by BAL protein and lactate-dehydrogenase content. Pro-inflammatory macrophage-derived cytokine osteopontin was higher, but galectin-3 lower in female mutants. CXCL5 and lipocalin-2 markers, attributed to epithelial cell stimulation did not differ. CONCLUSIONS: Despite general genotype-related differences, we had to reject our hypothesis of an increased CNP induced lung inflammation and an impairment of its resolution in PPARγ defective mice. Although earlier studies showed ligand-induced activation of nuclear receptor PPARγ to promote resolution of lung inflammation, its reduced activity did not provide signs of resolution impairment in the settings investigated here.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Harmonic Generation from Relativistic Plasma Surfaces in Ultra-Steep Plasma Density Gradients

Harmonic generation in the limit of ultra-steep density gradients is studied experimentally. Observations demonstrate that while the efficient generation of high order harmonics from relativistic surfaces requires steep plasma density scale-lengths ($L_p/\lambda < 1$) the absolute efficiency of the harmonics declines for the steepest plasma density scale-length $L_p \to 0$, thus demonstrating that near-steplike density gradients can be achieved for interactions using high-contrast high-intensity laser pulses. Absolute photon yields are obtained using a calibrated detection system. The efficiency of harmonics reflected from the laser driven plasma surface via the Relativistic Oscillating Mirror (ROM) was estimated to be in the range of 10^{-4} - 10^{-6} of the laser pulse energy for photon energies ranging from 20-40 eV, with the best results being obtained for an intermediate density scale-length

Female home range size is regulated by resource distribution and intraspecific competition: a long-term field study

The size of an individual’s home range is an important feature, influencing reproduction and survival, but it can vary considerably among both populations and individuals. The factors accounting for such variation are still poorly understood, and comprehensive long-term field studies considering various environmental factors that influence home range size are rare. We investigated the effects of seasonality, availability of food, cover, number of direct neighbours and the relative individual body mass on home range sizes in 125 adult female striped mice, Rhabdomys pumilio, in South Africa from 2004 to 2008. We used radiotelemetry to estimate home range sizes, trapping to determine the number of direct neighbours, and plant surveys in every home range to determine availability of food and cover. Home ranges were smaller when food quantity was high, many territorial neighbours were present, females had a relatively small body mass and during the nonbreeding season. We conclude that the availability of food resources and intraspecific competition are the main factors influencing home range size in female striped mice. Females enlarged their home ranges when territorial neighbours were few, and there was a significant positive correlation between home range size and quantity of food plants. This indicates that home range size might not reflect the minimal trade-off between access to resources that allow for a female’s survival and lowest cost for defending and foraging in that area. Instead, we propose a hypothesis for future research that female striped mice occupy areas several times larger than needed to improve their fitness by providing resources for future offspring

Editorial: radioimmunotherapy—translational opportunities and challenges

It has become evident that radiotherapy has both, immune suppressive, and immune activating properties (1). This is why this important component of cancer treatment should be combined with immune therapies to shift the balance toward immune activation against tumor cells. During the last decade a manifold of pre-clinical work was put into investigation of combination of radiotherapy either with additional immune stimulants such as cytokines or vaccines or in combination with antibodies that target immune suppressive molecules such as immune checkpoint inhibitors. Luckily, some of these approaches are currently tested in clinical trials, high lightening the huge translational opportunities by examination of modes of action of radiotherapy in combination with immunotherapy; named in this special issue radioimmunotherapy. However, one has always to keep in mind that many challenges do still exist such as what is the best sequence and timing of joint applications, what are the best immunotherapy approaches, how to overcome tumor resistances, what about healthy tissue cytotoxicity, or which biomarkers or matrices of biomarkers are most beneficial for patients stratification, just to mention the most burning ones. The articles in this special issue grab many of these challenges