657 research outputs found
Sort by
Neurogenomic mechanisms of social plasticity
Get PDFGroup-living animals must adjust the expression of their social behaviour to changes in their social environment and to transitions between life-history stages, and this social plasticity can be seen as an adaptive trait that can be under positive selection when changes in the environment outpace the rate of genetic evolutionary change. Here, we propose a conceptual framework for understanding the neuromolecular mechanisms of social plasticity. According to this framework, social plasticity is achieved by rewiring or by biochemically switching nodes of a neural network underlying social behaviour in response to perceived social information. Therefore, at the molecular level, it depends on the social regulation of gene expression, so that different genomic and epigenetic states of this brain network correspond to different behavioural states, and the switches between states are orchestrated by signalling pathways that interface the social environment and the genotype. Different types of social plasticity can be recognized based on the observed patterns of inter- versus intra-individual occurrence, time scale and reversibility. It is proposed that these different types of social plasticity rely on different proximate mechanisms at the physiological, neural and genomic level.Fundação para a Ciência e a Tecnologia fellowships: (SFRH/BD/89072/2012, SFRH/BD/44848/2008); FCT grant: (EXCL/BIA-ANM/0549/2012)
Tigers of Sundarbans in India: Is the Population a Separate Conservation Unit?
Get PDFThe Sundarbans tiger inhabits a unique mangrove habitat and are morphologically distinct from the recognized tiger subspecies in terms of skull morphometrics and body size. Thus, there is an urgent need to assess their ecological and genetic distinctiveness and determine if Sundarbans tigers should be defined and managed as separate conservation unit. We utilized nine microsatellites and 3 kb from four mitochondrial DNA (mtDNA) genes to estimate genetic variability, population structure, demographic parameters and visualize historic and contemporary connectivity among tiger populations from Sundarbans and mainland India. We also evaluated the traits that determine exchangeability or adaptive differences among tiger populations. Data from both markers suggest that Sundarbans tiger is not a separate tiger subspecies and should be regarded as Bengal tiger (P. t. tigris) subspecies. Maximum likelihood phylogenetic analyses of the mtDNA data revealed reciprocal monophyly. Genetic differentiation was found stronger for mtDNA than nuclear DNA. Microsatellite markers indicated low genetic variation in Sundarbans tigers (He= 0.58) as compared to other mainland populations, such as northern and Peninsular (Hebetween 0.67- 0.70). Molecular data supports migration between mainland and Sundarbans populations until very recent times. We attribute this reduction in gene flow to accelerated fragmentation and habitat alteration in the landscape over the past few centuries. Demographic analyses suggest that Sundarbans tigers have diverged recently from peninsular tiger population within last 2000 years. Sundarbans tigers are the most divergent group of Bengal tigers, and ecologically non-exchangeable with other tiger populations, and thus should be managed as a separate "evolutionarily significant unit" (ESU) following the adaptive evolutionary conservation (AEC) concept.Wildlife Institute of India, Dehra Dun (India)
Social Eavesdropping in Zebrafish: Tuning of Attention to Social Interactions
Get PDFGroup living animals may eavesdrop on signalling interactions between conspecifics in order to collect adaptively relevant information obtained from others, without incurring in the costs of first-hand information acquisition. This ability (aka social eavesdropping) is expected to impact Darwinian fitness, and hence predicts the evolution of cognitive processes that enable social animals to use public information available in the environment. These adaptive specializations in cognition may have evolved both at the level of learning and memory mechanisms, and at the level of input mechanisms, such as attention, which select the information that is available for learning. Here we used zebrafish to test if attention in a social species is tuned to the exchange of information between conspecifics. Our results show that zebrafish are more attentive towards interacting (i.e. fighting) than towards non-interacting pairs of conspecifics, with the exposure to fighting not increasing activity or stress levels. Moreover, using video playbacks to manipulate form features of the fighting fish, we show that during the assessment phase of the fight, bystanders' attention is more driven by form features of the interacting opponents; whereas during the post-resolution phase, it is driven by biological movement features of the dominant fish chasing the subordinate fish.FCT fellowship: (SFRH/BD/33280/2007), Champalimaud Neuroscience Programme
Dilp8 requires the neuronal relaxin receptor Lgr3 to couple growth to developmental timing
Get PDFHow different organs in the body sense growth perturbations in distant tissues to coordinate their size during development is poorly understood. Here we mutate an invertebrate orphan relaxin receptor gene, the Drosophila Leucine-rich repeat-containing G protein-coupled receptor 3 (Lgr3), and find body asymmetries similar to those found in insulin-like peptide 8 (dilp8) mutants, which fail to coordinate growth with developmental timing. Indeed, mutation or RNA intereference (RNAi) against Lgr3 suppresses the delay in pupariation induced by imaginal disc growth perturbation or ectopic Dilp8 expression. By tagging endogenous Lgr3 and performing cell type-specific RNAi, we map this Lgr3 activity to a new subset of CNS neurons, four of which are a pair of bilateral pars intercerebralis Lgr3-positive (PIL) neurons that respond specifically to ectopic Dilp8 by increasing cAMP-dependent signalling. Our work sheds new light on the function and evolution of relaxin receptors and reveals a novel neuroendocrine circuit responsive to growth aberrations.FCT Investigator Programme: (PD/BD/52421/2013), FCT fellowship: (SFRH/BPD/94112/2013, SFRH/BD/94931/2013, SFRH/BPD/74313/2010), CONICET and UNS, CONICET fellowship, CEDOC, N.P. Rotstein and L.E. Politi
Studies in the mouse model identify strain variability as a major determinant of disease outcome in Leishmania infantum infection
Get PDFVisceral leishmaniasis is a severe and potentially fatal disease caused by protozoa of the genus Leishmania, transmitted by phlebotomine sandflies. In Europe and the Mediterranean region, L. infantum is the commonest agent of visceral leishmaniasis, causing a wide spectrum of clinical manifestations, including asymptomatic carriage, cutaneous lesions and severe visceral disease. Visceral leishmaniasis is more frequent in immunocompromised individuals and data obtained in experimental models of infection have highlighted the importance of the host immune response, namely the efficient activation of host's macrophages, in determining infection outcome. Conversely, few studies have addressed a possible contribution of parasite variability to this outcome.No funders or funding refered in the paper
The value of the spineless monkey orange tree (Strychnos madagascariensis) for conservation of northern sportive lemurs (Lepilemur milanoii and L. ankaranensis)
Get PDFTree hollows provide shelters for a large number of forest-dependent vertebrate species worldwide. In Madagascar, where high historical and ongoing rates of deforestation and forest degradation are responsible for a major environmental crisis, reduced availability of tree hollows may lead to declines in hollow-dwelling species such as sportive lemurs, one of the most species-rich groups of lemurs. The identification of native tree species used by hollow-dwelling lemurs may facilitate targeted management interventions to maintain or improve habitat quality for these lemurs. During an extensive survey of sportive lemurs in northern Madagascar, we identified one tree species, Strychnos madagascariensis
(Loganiaceae), the spineless monkey orange tree, as a principal sleeping site of two species of northern sportive lemurs, Lepilemur ankaranensis and L. milanoii (Lepilemuridae). This tree species
represented 32.5% (n=1 50) of the 458 sleeping sites recorded. This result suggests that S. madagascariensis may be valuable for the conservation of hollow-dwelling lemurs.FCT grant: (SFRH/BD/64875/2009), GDRI Madagascar, the Laboratoire d’Excellence (LABEX) entitled TULIP
(ANR-1 0-LABX-41 ), the Rufford Small Grant Foundation grant: (10941 -1), Instituto Gulbenkian de Ciência, the LIA BEEG-B (Laboratoire International Associé - Bioinformatics, Ecology, Evolution, Genomics and Behaviour) (CNRS), National Science Foundation grant: (DEB-1 25791 6)
Differences in larval nutritional requirements and female oviposition preference reflect the order of fruit colonization of Zaprionus indianus and Drosophila simulans
Get PDFSpecies coexist using the same nutritional resource by partitioning it either in space or time, but few studies explore how species-specific nutritional requirements allow partitioning. Zaprionus indianus and Drosophila simulans co-exist in figs by invading the fruit at different stages; Z. indianus colonizes ripe figs, whereas D. simulans oviposits in decaying fruit. Larvae feed on yeast growing on the fruit, which serves as their primary protein source. Because yeast populations increase as fruit decays, we find that ripe fruit has lower protein content than rotting fruit. Therefore, we hypothesized that Z. indianus and D. simulans larvae differ in their dietary requirements for protein. We used nutritional geometry to assess the effects of protein and carbohydrate concentration in the larval diet on life history characters in both species. Survival, development time, and ovariole number respond differently to the composition of the larval diet, with Z. indianus generally performing better across a wider range of protein concentrations. Correspondingly, we found that Z. indianus females preferred to lay eggs on low protein foods, while D. simulans females chose higher protein foods for oviposition when competing with Z. indianus. We propose the different nutritional requirements and oviposition preference of these two species allows them to temporally partition their habitat.Ph.D. and PDSE scholarships from CNPq and Capes: (proc. 140903/2010-0 and proc. BEX
12281/12-3 respectively)
Multifaceted Role of Heme during Severe Plasmodium falciparum Infections in India
Get PDFSeveral immunomodulatory factors are involved in malaria pathogenesis. Among them, heme has been shown to play a role in the pathophysiology of severe malaria in rodents, but its role in human severe malaria remains unclear. Circulating levels of total heme and its main scavenger, hemopexin, along with cytokine/chemokine levels and biological parameters, including hemoglobin and creatinine levels, as well as transaminase activities, were measured in the plasma of 237 Plasmodium falciparum-infected patients living in the state of Odisha, India, where malaria is endemic. All patients were categorized into well-defined groups of mild malaria, cerebral malaria (CM), or severe noncerebral malaria, which included acute renal failure (ARF) and hepatopathy. Our results show a significant increase in total plasma heme levels with malaria severity, especially for CM and malarial ARF. Spearman rank correlation and canonical correlation analyses have shown a correlation between total heme, hemopexin, interleukin-10, tumor necrosis factor alpha, gamma interferon-induced protein 10 (IP-10), and monocyte chemotactic protein 1 (MCP-1) levels. In addition, canonical correlations revealed that heme, along with IP-10, was associated with the CM pathophysiology, whereas both IP-10 and MCP-1 together with heme discriminated ARF. Altogether, our data indicate that heme, in association with cytokines and chemokines, is involved in the pathophysiology of both CM and ARF but through different mechanisms.Indo-French Centre for the Promotion of Advanced Research; Associated International Laboratory Systems; Immunology and Genetics of Infectious Diseases; Department of Biotechnology from the Ministry of Science and Technology of India; Tata Institute of Fundamental Research intramural funds; Université Lille 1 (doctoral contract); IFCPAR (Raman-Charpak award); College Doctoral Lille Nord de France (AAP n10 award); Fondation des Treilles; Conseil Régional du Nord-Pas de Calais
Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback
Get PDFSister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC), is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response resulting in abnormal mitotic exit after a short delay. Quantitative live-cell imaging approaches combined with mathematical modeling indicate that weak SAC activation upon cohesion loss is caused by weak signal generation. This is further attenuated by several feedback loops in the mitotic signaling network. We propose that multiple feedback loops involving cyclin-dependent kinase 1 (Cdk1) gradually impair error-correction efficiency and accelerate mitotic exit upon premature loss of cohesion. Our findings explain how cohesion defects may escape SAC surveillance.Fundação para a Ciência e Tecnologia PhD scholarship: (SFRH/BD/52438/2013); Boehringer Ingelheim Fonds PhD fellowship program and EPSRC; Marie Curie Career Integration Grant: (MCCIG321883/CCC); EMBO Installation Grant: (IG2778); BBSRC sLoLa: (BB/MM00354X/1)
Species differential regulation of COX2 can be described by an NFκB-dependent logic AND gate
Get PDFThere are no funders and sponsors indicated explicitly in the document. The upload is composed by two files: the main article and supplementary materials (both in pdf format).Cyclooxygenase 2 (COX2), a key regulatory enzyme of the prostaglandin/eicosanoid pathway, is an important target for anti-inflammatory therapy. It is highly induced by pro-inflammatory cytokines in a Nuclear factor kappa B (NFκB)-dependent manner. However, the mechanisms determining the amplitude and dynamics of this important pro-inflammatory event are poorly understood. Furthermore, there is significant difference between human and mouse COX2 expression in response to the inflammatory stimulus tumor necrosis factor alpha (TNFα). Here, we report the presence of a molecular logic AND gate composed of two NFκB response elements (NREs) which controls the expression of human COX2 in a switch-like manner. Combining quantitative kinetic modeling and thermostatistical analysis followed by experimental validation in iterative cycles, we show that the human COX2 expression machinery regulated by NFκB displays features of a logic AND gate. We propose that this provides a digital, noise-filtering mechanism for a tighter control of expression in response to TNFα, such that a threshold level of NFκB activation is required before the promoter becomes active and initiates transcription. This NFκB-regulated AND gate is absent in the mouse COX2 promoter, most likely contributing to its differential graded response in promoter activity and protein expression to TNFα. Our data suggest that the NFκB-regulated AND gate acts as a novel mechanism for controlling the expression of human COX2 to TNFα, and its absence in the mouse COX2 provides the foundation for further studies on understanding species-specific differential gene regulation.There are no funders and sponsors indicated explicitly in the document.info:eu-repo/semantics/publishedVersio