Breeding performance of the Barn Swallow (Hirundo rustica) in a North African urban area: what are the impacts of climatic conditions and insecticide applications?

La présente étude analyse les effets des conditions climatiques (température, précipitations et vitesse des vents) et de l’activité anthropique (traitements aux insecticides) sur la taille de ponte, le nombre d’oeufs éclos et la productivité totale de l’Hirondelle rustique dans un milieu urbain Nord-Africain (Guelma, Algérie). Les résultats ont démontré que les conditions climatiques n’affectent pas clairement les paramètres de reproduction de cet Hirundinidé, contrairement aux traitements insecticides des bâtiments de nidification. Les trois paramètres étudiés ont tous subi une importante diminution au fur et à mesure de la progression de la saison de reproduction. Le nombre d’oeufs éclos et la productivité totale ont été plus grands pour la première ponte que pour la seconde. Cette productivité a nettement diminuée en 2013 par comparaison à 2012. La poursuite des recherches sur d’autres facteurs environnementaux comme : (i) la disponibilité des insectes ; (ii) l’activité agricole et (iii) les événements météorologiques défavorables, s’avère une piste incontournable pour la mise en oeuvre de mesures de gestion visant l’amélioration des conditions locales de reproduction de cette population urbaine Nord-Africaine.The present study examined the effects of climate conditions (temperature, precipitation and wind speed) and human activity (insecticide treatment) on clutch size, number of hatchlings and total productivity of the Barn Swallow in a North African urban area (Guelma, Algeria). Our results demonstrated that climatic conditions did not clearly affect reproductive parameters of this Hirundinidae, unlike insecticide treatments inside nesting-buildings. A seasonal decline of the three studied parameters was recorded. The number of hatchlings and total productivity were greater for first than for second clutches. Likewise, productivity significantly decreased in 2013 compared to 2012. Further research on other environmental factors such as: (i) insect availability; (ii) agricultural activity and (iii) adverse weather events, are an essential track for the implementation of management measures to improve local breeding conditions of this North African urban population

Estivation-responsive microRNAs in a hypometabolic terrestrial snail

When faced with extreme environmental conditions, the milk snail (Otala lactea) enters a state of dormancy known as estivation. This is characterized by a strong reduction in metabolic rate to <30% of normal resting rate that is facilitated by various behavioural, physiological, and molecular mechanisms. Herein, we investigated the regulation of microRNA in the induction of estivation. Changes in the expression levels of 75 highly conserved microRNAs were analysed in snail foot muscle, of which 26 were significantly upregulated during estivation compared with controls. These estivation-responsive microRNAs were linked to cell functions that are crucial for long-term survival in a hypometabolic state including anti-apoptosis, cell-cycle arrest, and maintenance of muscle functionality. Several of the microRNA responses by snail foot muscle also characterize hypometabolism in other species and support the existence of a conserved suite of miRNA responses that regulate environmental stress responsive metabolic rate depression across phylogeny

Moroccan rock phosphate solubilization during a thermo-anaerobic grassland waste biodegradation process

In order to investigate the presence of thermo-tolerant rock phosphate (RP) solubilizing anaerobic microbes during the fermentation process, we used grassland as sole organic substrate to evaluate the RP solubilization process under anaerobic thermophilic conditions. The result shows a significant decrease of pH from 6.5 to 4.8, and solubilizing from 7 to 15.8% of the phosphorus from the RP in the reactors after 90 days of incubation at 45°C. In these conditions, the organic acids produced were qualitatively and quantitatively identified as: acetic, butyric and propionic acids. This biological RP solubilization is due to the presence of a single thermo-tolerant bacterium isolated and identified as Bacillus subtilis from the anaerobic reactors. This B. subtilis strain was shown to be able to solubilize RP in liquid cultures containing insoluble RP as sole phosphate source. The mechanisms involved in these weathering processes confirmed the production of organic acids which were identified and quantified. This study is expected to lead to the development of novel, non-polluting farming practices by entering in the formulation of novel multi-functional biofertilizer by inoculating this thermo-tolerant phosphate-solubilizing bacterium into agricultural wastes as a practical and environmental strategy.Key words: Grassland, phosphate, solubilization, Bacillus subtilis, thermo-anaerobic conditions

Synthesis and biological evaluation of novel N-phenyl ureidobenzenesulfonate derivatives as potential anticancer agents. Part 2. Modulation of the ring B

DNA double strand-breaks (DSBs) are the most deleterious lesions that can affect the genome of living beings and are lethal if not quickly and properly repaired. Recently, we discovered a new family of anticancer agents designated as N-phenyl ureidobenzenesulfonates (PUB-SOs) that are blocking the cells cycle progression in S-phase and inducing DNA DSBs. Previously, we have studied the effect of several modifications on the molecular scaffold of PUB-SOs on their cytocidal properties. However, the effect of the nature and the position of substituents on the aromatic ring B is still poorly studied. In this study, we report the preparation and the biological evaluation of 45 new PUB-SO derivatives substituted by alkyl, alkoxy, halogen and nitro groups at different positions on the aromatic ring B. All PUB-SOs were active in the submicromolar to low micromolar range (0.24–20 μM). The cell cycle progression analysis showed that PUB-SOs substituted at position 2 by alkyl, halogen or nitro groups or substituted at position 4 by a hydroxyl group arrest the cell cycle progression in S-phase. Interestingly, all others PUB-SOs substituted at positions 3 and 4 arrested the cell cycle in G2/M-phase. PUB-SOs arresting the cell cycle progression in S-phase also induced the phosphorylation of H2AX (γH2AX) which is indicating the generation of DNA DSBs. We evidenced that few modifications on the ring B of PUB-SOs scaffold lead to cytocidal derivatives arresting the cell cycle in S-phase and inducing γH2AX and DSBs. In addition, this study shows that these new anticancer agents are promising and could be used as alternative to circumvent some of the biopharmaceutical complications that might be encountered during the development of PUB-SOs

MicroRNAs regulate survival in oxygen-deprived environments

Some animals must endure prolonged periods of oxygen deprivation to survive. One such extreme model is the northern crayfish (Orconectes virilis), that regularly survives year-round hypoxic and anoxic stresses in its warm stagnant summer waters and in its cold, ice-locked winter waters. To elucidate the molecular underpinnings of anoxia resistance in this natural model, we surveyed the expression profiles of 76 highly conserved microRNAs in crayfish hepatopancreas and tail muscle from normoxic, acute 2 h anoxia, and chronic 20 h anoxia exposures. MicroRNAs are known to regulate a diverse array of cellular functions required for environmental stress adaptations, and here we explored their role in anoxia tolerance. The tissue-specific anoxia responses observed herein, with 22 anoxia-responsive microRNAs in the hepatopancreas and only four in muscle, suggest that microRNAs facilitate a reprioritization of resources to preserve crucial organ functions. Bioinformatic microRNA target enrichment analysis predicted that the anoxia-downregula

Determinants of nesting success in Turtle doves (Streptopelia turtur) in a North-African agricultural area

Connaître les effets des facteurs écologiques sur le succès de la reproduction de l’avifaune migratrice nicheuse est primordial particulièrement dans les milieux artificialisés. Nous avons étudié, au moyen de régressions de Poisson, l’influence de l’emplacement des nids sur les arbres, de la proximité aux cultures céréalière et aux points d’eau sur le nombre de jeunes à l’envol par nid (N=207), en tenant compte de possibles différences phénologiques et spatiales entre les cinq vergers étudiés. Le meilleur modèle, sélectionné sur la base du critère d’Akaike, montre des effets linéaires positifs de la distance du nid au tronc et aux plus proches cultures céréalières, et un effet quadratique de la hauteur du nid (avec un optimum à 1,6m). Dans les orangeraies de Guelma, le positionnement des nids et leur proximité aux cultures céréalières ont une incidence directe sur la productivité totale des Tourterelles des bois. La poursuite des recherches sur d’autres supports de nidification (arbres fruitiers et forestiers) s’avère nécessaire pour : (i) évaluer leur importance pour la reproduction de l’espèce et (ii) connaître l’effet des variables environnementales sur le maintien de l’espèce.Determining the effects of environmental factors on nesting success of migrant and breeding game birds is paramount especially in man-made environments. Using Poisson regression, we investigated the influence on the number of chicks fledged per nest (N = 207) of nest placement, proximity of cereal crops and water sources, taking into account possible phenological and spatial differences between the five studied orchards. The best model, selected by Akaike criterion, shows positive linear effects of distance from the nest to the trunk, to closest cereal crops and a quadratic effect of nest height (with an optimum at 1.6m). In Guelma’s orange groves, nest placement and proximity to cereal crops have a direct impact on the productivity of Turtle doves. Further researches on other tree species (fruit and forest ones) are necessary to: (i) assess their importance for breeding Turtle doves and (ii) determine the effect of environmental variables on the maintenance of the species

The role of MEF2 transcription factors in dehydration and anoxia survival in Rana sylvatica skeletal muscle

The wood frog (Rana sylvatica) can endure freezing of up to 65% of total body water during winter. When frozen, wood frogs enter a dormant state characterized by a cessation of vital functions (i.e., no heartbeat, blood circulation, breathing, brain activity, or movement). Wood frogs utilize various behavioural and biochemical adaptations to survive extreme freezing and component anoxia and dehydration stresses, including a global suppression of metabolic functions and gene expression. The stress-responsive myocyte enhancer factor-2 (MEF2) transcription factor family regulates the selective expression of genes involved in glucose transport, protein quality control, and phosphagen homeostasis. This study examined the role of MEF2A and MEF2C proteins as well as select downstream targets (glucose transporter-4, calreticulin, and muscle and brain creatine kinase isozymes) in 40% dehydration and 24 h anoxia exposure at the transcriptional, translational, and post-translational levels using qRT-PCR, immunoblotting, and subcellular localization. Mef2a/c transcript levels remained const

The hibernating South American marsupial, Dromiciops gliroides, displays torpor-sensitive microRNA expression patterns

When faced with adverse environmental conditions, the marsupial Dromiciops gliroides uses either daily or seasonal torpor to support survival and is the only known hibernating mammal in South America. As the sole living representative of the ancient Order Microbiotheria, this species can provide crucial information about the evolutionary origins and biochemical mechanisms of hibernation. Hibernation is a complex energy-saving strategy that involves changes in gene expression that are elicited in part by microRNAs. To better elucidate the role of microRNAs in orchestrating hypometabolism, a modified stem-loop technique and quantitative PCR were used to characterize the relative expression levels of 85 microRNAs in liver and skeletal muscle of control and torpid D. gliroides. Thirty-nine microRNAs were differentially regulated during torpor; of these, 35 were downregulated in liver and 11 were differentially expressed in skeletal muscle. Bioinformatic analysis predicted that the downregulated liver microRNAs were associated with activation of MAPK, PI3K-Akt and mTOR pathways, suggesting their importance in facilitating marsupial torpor. In skeletal muscle, hibernation-responsive microRNAs were predicted to regulate focal adhesion, ErbB, and mTOR pathways, indicating a promotion of muscle maintenance mechanisms. These tissue-specific responses suggest that microRNAs regulate key molecular pathways that facilitate hibernation, thermoregulation, and prevention of muscle disuse atrophy.Link_to_subscribed_fulltex