Pluripotent mouse embryonic stem cells maintain their identity throughout virtually infinite cell divisions. This phenomenon, referred to as self-renewal, depends on a network of sequence-specific ...transcription factors (TFs) and requires daughter cells to accurately reproduce the gene expression pattern of the mother. However, dramatic chromosomal changes take place in mitosis, generally leading to the eviction of TFs from chromatin. Here, we report that Esrrb, a major pluripotency TF, remains bound to key regulatory regions during mitosis. We show that mitotic Esrrb binding is highly dynamic, driven by specific recognition of its DNA-binding motif and is associated with early transcriptional activation of target genes after completion of mitosis. These results indicate that Esrrb may act as a mitotic bookmarking factor, opening another perspective to molecularly understand the role of sequence-specific TFs in the epigenetic control of self-renewal, pluripotency and genome reprogramming.
A carcass is defined as a temporary resource that can support high levels of diversity compared to other resources. The level of diversity often depends on the environmental conditions in which the ...corpse is found. Calliphoridae (Diptera) are the most important necrophagous insects used in forensic investigations because this family is common, widespread, abundant, and usually the first to colonize a corpse. However, understanding the processes responsible for variation in calliphorid species abundance and richness along gradients in ecology remains a key challenge. In this study, we analyzed the influence of altitude on the abundance and diversity of Calliphoridae species in corpses at three different altitudes (400, 900, and 1500 m a.s.l.) in a mountainous area of southeastern Spain. The results revealed a gradient of decreasing abundance with increasing altitude. An altitudinal substitution of species was observed, with Chrysomya albiceps being found at the lowest altitude and Calliphora vicina at the highest altitude. Seasonal variation was also noted, with Ch. albiceps being the dominant species in the warmer months and C. vicina being the dominant species in winter. Our results confirm the importance of Calliphorids as seasonal, altitudinal, and environmental indicators, given the wide distribution and abundance of this family. This information is of great interest on the interpretation of data in forensic practice.
The general aim of this work has been to check the ecological impact of metals on the Ebro river basin. In order to evaluate this, metal behavior considering water, sediment as well as metal ...bioaccumulation in fish has been studied. Total concentrations of metals, as well as the potentially bioavailable fraction of metals in sediment has also been analyzed by the application of the sequential extraction method (BCR method). In order to evaluate the influence of metal pollution on the river ecological status, according to the Water Framework Directive (WFD), diverse biological indices such as macroinvertebrates (IBMWP), diatoms (IPS) and macrophytes (IVAM), have been considered from an integrated point of view. Considering both water and sediment, metals which contributed in higher extend to the reduction of biological quality have been demonstrated to be Pb and Zn, as they presented a negative influence on macroinvertebrates, diatoms and macrophytes communities. As and Cr that seemed to have a significant influence on macroinvertebrates and diatoms too, while Ni negatively influenced only diatom communities. This study also demonstrated that monitoring programs only based on total metal determination in water are inefficient, as metals present even at undetectable concentrations in water are strongly accumulated in fish. Moreover, the high concentrations of Hg found in sediments indicated that this river basin may present pollution problems regarded to this metal, as demonstrated by the high Hg levels found in fish.
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•Hg, Cr, Zn, and Cu in sediments could reach values of concern although in water were undetectable.•BCR method allows distinguish between geological and anthropic pollution of metals.•Undetected Hg, Cd and Cr water concentrations are not guarantee of no bioaccumulation in fish.•Diatoms presented higher sensitivity to metals compared with macroinvertebates and macrophytes.•Pb, Zn, As, Cr and Ni seem to contribute in higher extend in the reduction of biological quality.
The aim of this work is to predict the bioavailability of the Potentially Toxic Elements (PTEs) Cd, Pb, Hg, Ni, Cu, Zn, As, Cr and Se in 6 sites within the Ebro River basin. In situ Diffusive ...gradient in thin-films (DGTs) and classical sampling have been used and compared. The potentially bioavailable fractions of each PTE was estimated by modelling their chemical speciation using three programs (WHAM 7.0, Visual MINTEQ 3.1 and Bio-met), following the suggestions published in recent European regulations. Results of the equilibrium-based models WHAM 7.0 and Visual MINTEQ 3.1 indicate that As, Cd, Ni, Se and Zn, predominate as free metals ions or forming inorganic soluble complexes. Copper, Pb and Hg bioavailability is conditioned by their affinity to dissolved humic substances. According to Visual MINTEQ 3.1, Cr is subjected to redox reactions, being Cr (VI) present (at low concentrations) in the studied rivers. According to Bio-met model, the bioavailability of Cu and Zn is highly influenced by soluble organic matter and water hardness, respectively. For most PTEs, the bioavailability estimated by deploying DGTs in river waters tends to be slightly lower than the estimation obtained with speciation models, since in real conditions more environmental factors take place comparing to the finite number of parameters considered in models.
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•Bio-met predictions for Zn and Cu are in agreement, with DGTs results.•WHAM 7.0 is useful when speciation is driven by dissolved organic matter (i.e. Cu).•Both WHAM 7.0 and Visual MINTEQ bring similar predictions for Zn, Ni, Cd and Hg.•Visual MINTEQ is useful for Cr and As speciation because considers redox reactions.
Mitotic bookmarking transcription factors (BFs) maintain the capacity to bind to their targets during mitosis, despite major rearrangements of the chromatin. While they were thought to propagate gene ...regulatory information through mitosis by statically occupying their DNA targets, it has recently become clear that BFs are highly dynamic in mitotic cells. This represents both a technical and a conceptual challenge to study and understand the function of BFs: First, formaldehyde has been suggested to be unable to efficiently capture these transient interactions, leading to profound contradictions in the literature; and second, if BFs are not permanently bound to their targets during mitosis, it becomes unclear how they convey regulatory information to daughter cells. Here, comparing formaldehyde to alternative fixatives we clarify the nature of the chromosomal association of previously proposed BFs in embryonic stem cells: While ESRRB can be considered as a canonical BF that binds at selected regulatory regions in mitosis, SOX2 and POU5F1 (also known as OCT4) establish DNA sequence-independent interactions with the mitotic chromosomes, either throughout the chromosomal arms (SOX2) or at pericentromeric regions (POU5F1). Moreover, we show that ordered nucleosomal arrays are retained during mitosis at ESRRB bookmarked sites, whereas regions losing transcription factor binding display a profound loss of order. By maintaining nucleosome positioning during mitosis, ESRRB might ensure the rapid post-mitotic re-establishment of functional regulatory complexes at selected enhancers and promoters. Our results provide a mechanistic framework that reconciles dynamic mitotic binding with the transmission of gene regulatory information across cell division.
According to the European Water Framework Directive (WFD), assessment of surface water status is based on ecological and chemical status that is not always in coherence. In these situations, ...ecotoxicity tests could help to obtain a better characterization of the ecosystems. The general aim of this work is to design a methodology to study the ecotoxicological status of freshwater systems. This could be useful and complementary to ecological status, for a better ecological characterization of freshwater systems. For this purpose, sediments from thirteen sampling sites within the Ebro river watershed (NE Spain) were collected for ecotoxicity characterization. The ecotoxicity of pore water has been evaluated employing the test organisms Vibrio fischeri, Pseudokirschneriella subcapitata and Daphnia magna, while whole sediment ecotoxicity was evaluated using Vibrio fischeri, Daphnia magna, Nitzschia palea and Chironomus riparius. An analysis of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) was performed to evaluate the sediment toxicity associated to bioavailable metals. Moreover, data about priority pollutants defined by the WFD in water, sediment and fish as well as data of surface water status of each sampling point were provided by the Monitoring and Control Program of the Ebro Water bodies. In general terms, whole sediment bioassays have shown more toxicity than pore water tests. Among the different organisms used, P. subcapitata and C. riparius were the most sensitive in pore water and whole sediment, respectively. Our evaluation of the ecotoxicological status showed high coincidences with the ecological status, established according to the WFD, especially when ecosystem disruption due to numerous stressors (presence of metals and organic pollution) was observed. These results allow us to confirm that, when chemical stressors affect the ecosystem functioning negatively, an ecotoxicological approach, provided by suitable bioassays in pore water and whole sediment, could detect these changes with accurate sensitivity.
•Whole sediment bioassays have shown more sensitivity than pore water tests.•Ecotoxicity approach has been in agreement with the ecological status in the most polluted sites.•A toolbox of ecotoxicity tests has shown a high potential to complement the ecological status of rivers.
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•Pest densities in melon fields were similar with and without the use of pesticides.•Natural enemy abundance was higher in unsprayed versus conventional fields.•Orius spp. was the ...dominant predator most likely controlling key pest species.•Conservation biological control could be a viable alternative to pesticides in this system.
Pest control in Mediterranean open-field melon crops currently relies on repeated pesticide applications. A lack of IPM programs that take into account naturally occurring biological control agents in the crop could be due, in part, to a lack of knowledge of the natural enemies associated with melon and their pest control potential. We estimated the abundance of pests and natural enemies in fields managed with a conventional insecticide regime (CPR) and a ‘no insecticide’ regime (NPR), with all fields receiving fungicide applications (sulphur or triadimenol), as required. In a two-year study, six melon fields were sampled periodically during spring and early summer by visual observations of leaves and the extraction of arthropods from flowers using Berlese funnels. The most abundant phytophagous arthropods on melon leaves were thrips (38.9% of total counts), aphids (31.5%), spider mites (26.8%) and whiteflies (2.8%). Aphis gossypii was significantly more abundant in CPR than in NPR fields, whereas whiteflies and thrips had similar abundance in the two treatments. Spider mites were more abundant in NPR than in CPR fields. The main groups of natural enemies on leaves were Orius spp. (76.1% of total counts), phytoseiids (7.4%), predatory thrips (7.1%) and cecidomyiids (5.6%), and all were significantly more abundant in NPR than in CPR fields. The primary predators in flowers were Orius spp. (67.4%) and Aeolothrips spp. (32.6%), and both were significantly more abundant in NPR than in CPR fields. Orius spp. was inferred to be the primary biological control agent of aphids, as few aphids were mummified by parasitoids. The control of aphids by Orius spp. was probably mediated by apparent competition with thrips, which are a preferred prey of Orius spp. In summary, elimination of pesticides from the management regime enhanced the abundance of natural enemies in the melon crop, and natural biological control limited pest infestations in NPR fields as well as did broad-spectrum insecticides in CPR fields. Therefore, IPM strategies for melon production should consider conservation of natural biological control agents as an effective alternative to conventional regimes that rely primarily upon insecticides.
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