RESUMO
SARGASSUM SEAWEED AS SAULTS THE FRENCH WEST INDIES. Since 2011, Martinique and the islands of Guadeloupe have been affected by repeated groundings, culminating in an exceptional wave in 2018. While the sargassum ( Sargassum natans and S. fluitans ) involved in these phenomena are neither toxic nor urticating, indirect toxicity linked to the presence of microorganisms and heavy metals (arsenic, mercury, etc.) in sargassum clusters has been described. Similarly, after a 24 to 48 hours stay on the shore, sargassum algae enter a putrefaction cycle responsible to produce hydrogen sulfide (H2S) and ammonia (NH3). The acute toxicity of these gases is well known. However, very few data are available on the clinical effects of prolonged exposure to low doses of H2S and NH3. Our team has recently described the syndromic features of chronic exposure, supposing for deleterious effects on the cardiovascular, respiratory and neurological systems.
ALGUES SARGASSES À L'ASSAUT DES ANTILLES. Depuis 2011, la Martinique et les îles de la Guadeloupe sont touchées par des échouements à répétition d'algues sargasses qui ont culminé avec une vague exceptionnelle en 2018. Si les sargasses (Sargassum natans et S. fluitans) impliquées dans ces phénomènes ne sont ni toxiques ni urticantes, une toxicité indirecte liée à la présence de micro-organismes et de métaux lourds (arsenic, mercure ) dans les amas de sargasses est décrite. De même, après un séjour de vingt-quatre à quarante-huit heures sur le littoral, les algues sargasses entrent dans un cycle de putréfaction responsable de la production d'hydrogène sulfuré (H2S) et d'ammoniac (NH3). La toxicité aiguë de ces gaz est bien connue. Il existe en revanche très peu de données disponibles sur les effets cliniques d'une exposition prolongée à de faibles doses d'H2S ou NH3. Notre équipe a récemment décrit le tableau syndromique de l'exposition chronique et suppose des effets délétères sur le système cardiovasculaire, respiratoire et neurologique.
Assuntos
Sargassum , Alga Marinha , Humanos , Sulfeto de Hidrogênio/intoxicação , Sulfeto de Hidrogênio/toxicidade , Guadalupe/epidemiologia , Martinica/epidemiologia , Amônia/toxicidade , Índias Ocidentais/epidemiologia , Exposição Ambiental/efeitos adversosRESUMO
The objective of this work is to present the key elements in the design of emergency management and response plans in scenarios where there has been loss of containment of chemical agents of acute effect focused in the protection of not routinely exposed in a determined occupational environment. To this purpose, a validation of the current criteria for the management of accidental releases is carried out, taking into account hypothetical risk scenarios. The essential elements of the emergency management system are stated, from a systemic perspective and the corresponding risk control actions; recommendations for their implementation are showed, taking as prototype hydrogen sulfide, a highly toxic gas. Non controlled emissions of toxic gases of acute effect from an occupational standpoint represents a priority because of their human and financial high toll. Design and implementation of an appropriate emergency plan for uncontrollable emissions of toxics chemical agents must be addressed.
Assuntos
Gases/toxicidade , Exposição Ocupacional/prevenção & controle , Indústria de Petróleo e Gás , Gestão de Riscos/normas , Planejamento em Desastres/normas , Humanos , Sulfeto de Hidrogênio/toxicidade , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/normas , Fatores de TempoRESUMO
Sargassum constitutes an ancient marine ecosystem that circulates clockwise on the Atlantic Ocean. Upon 2011, the pelagic seaweed which is the main component of sargassum started to reach beaches on 19 Caribbean countries, with environmental, health and economic impacts that need to be addressed urgently.
El sargazo es un ecosistema marino milenario que circula en el sentido de las manecillas del reloj en el Océano Atlántico. A partir de 2011, el alga flotante que lo compone ha comenzado a recalar en playas de 19 países del Caribe, con consecuencias ambientales, sanitarias y económicas que deben atenderse con urgencia.
Assuntos
Praias , Ecossistema , Sulfeto de Hidrogênio/toxicidade , Sargassum/crescimento & desenvolvimento , Oceano Atlântico , Região do Caribe , Exposição Ambiental , Gases/toxicidade , Sargassum/química , Movimentos da ÁguaRESUMO
Resumen El sargazo es un ecosistema marino milenario que circula en el sentido de las manecillas del reloj en el Océano Atlántico. A partir de 2011, el alga flotante que lo compone ha comenzado a recalar en playas de 19 países del Caribe, con consecuencias ambientales, sanitarias y económicas que deben atenderse con urgencia.
Abstract Sargassum constitutes an ancient marine ecosystem that circulates clockwise on the Atlantic Ocean. Upon 2011, the pelagic seaweed which is the main component of sargassum started to reach beaches on 19 Caribbean countries, with environmental, health and economic impacts that need to be addressed urgently.
Assuntos
Praias , Ecossistema , Sargassum/crescimento & desenvolvimento , Sulfeto de Hidrogênio/toxicidade , Movimentos da Água , Oceano Atlântico , Região do Caribe , Sargassum/química , Exposição Ambiental , Gases/toxicidadeRESUMO
Vale dos Vinhedos appellation of origin has a very recent history as industrial wine making region. In this study we investigated the genetic and phenotypic variability of Saccharomyces cerevisiae strains isolated from South-Brazilian vineyards in order to evaluate strain fermentation aptitude and copper and sulphites tolerance. Merlot grape bunches were collected from three vineyards and yeast isolation was performed after single bunch fermentation. High genotypic variability was found and most of the genotypes revealed to be vine-specific. No industrial strain dissemination was present in the sampled vineyards, although it has been wildly reported in traditional winemaking countries. From the phenotypic traits analysis these Brazilian native strains showed good fermentation performances, good tolerance to sulphites and, in particular, a high copper tolerance level. Copper is the most important metal in the formulation of fungicides against downy mildew (Plasmopara viticola), one of the most harmful disease of the vines, and other fungal pests. The high tolerance to copper suggests an environmental adaptation to the strong use of copper-based fungicides, requested by the wet subtropical climate.
Assuntos
Variação Genética , Genótipo , Fenótipo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/fisiologia , Agricultura , Brasil , Cobre/toxicidade , Sulfato de Cobre/toxicidade , DNA Fúngico/genética , Tolerância a Medicamentos , Fazendas , Fermentação , Fungicidas Industriais/química , Fungicidas Industriais/toxicidade , Genes Fúngicos , Mapeamento Geográfico , Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/toxicidade , Cinética , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/isolamento & purificação , Dióxido de Enxofre/toxicidade , Vitis/química , Vitis/microbiologia , Vinho/microbiologiaRESUMO
To cope with toxic levels of H2S, the plant pathogens Xylella fastidiosa and Agrobacterium tumefaciens employ the bigR operon to oxidize H2S into sulfite. The bigR operon is regulated by the transcriptional repressor BigR and it encodes a bifunctional sulfur transferase (ST) and sulfur dioxygenase (SDO) enzyme, Blh, required for H2S oxidation and bacterial growth under hypoxia. However, how Blh operates to enhance bacterial survival under hypoxia and how BigR is deactivated to derepress operon transcription is unknown. Here, we show that the ST and SDO activities of Blh are in vitro coupled and necessary to oxidize sulfide into sulfite, and that Blh is critical to maintain the oxygen flux during A. tumefaciens respiration when oxygen becomes limited to cells. We also show that H2S and polysulfides inactivate BigR leading to operon transcription. Moreover, we show that sulfite, which is produced by Blh in the ST and SDO reactions, is toxic to Citrus sinensis and that X. fastidiosa-infected plants accumulate sulfite and higher transcript levels of sulfite detoxification enzymes, suggesting that they are under sulfite stress. These results indicate that BigR acts as a sulfide sensor in the H2S oxidation mechanism that allows pathogens to colonize plant tissues where oxygen is a limiting factor.
Assuntos
Agrobacterium tumefaciens/genética , Dioxigenases/genética , Transferases/genética , Xylella/genética , Agrobacterium tumefaciens/metabolismo , Dioxigenases/química , Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/toxicidade , Hipóxia/genética , Hipóxia/metabolismo , Óperon/genética , Oxigênio/metabolismo , Plantas/genética , Plantas/microbiologia , Estresse Fisiológico/genética , Sulfetos/química , Transferases/química , Xylella/metabolismoRESUMO
Replicated ecological gradients are prime systems to study processes of molecular evolution underlying ecological divergence. Here, we investigated the repeated adaptation of the neotropical fish Poecilia mexicana to habitats containing toxic hydrogen sulphide (H2 S) and compared two population pairs of sulphide-adapted and ancestral fish by sequencing population pools of >200 individuals (Pool-Seq). We inferred the evolutionary processes shaping divergence and tested the hypothesis of increase of parallelism from SNPs to molecular pathways. Coalescence analyses showed that the divergence occurred in the face of substantial bidirectional gene flow. Population divergence involved many short, widely dispersed regions across the genome. Analyses of allele frequency spectra suggest that differentiation at most loci was driven by divergent selection, followed by a selection-mediated reduction of gene flow. Reconstructing allelic state changes suggested that selection acted mainly upon de novo mutations in the sulphide-adapted populations. Using a corrected Jaccard index to quantify parallel evolution, we found a negligible proportion of statistically significant parallel evolution of Jcorr = 0.0032 at the level of SNPs, divergent genome regions (Jcorr = 0.0061) and genes therein (Jcorr = 0.0091). At the level of metabolic pathways, the overlap was Jcorr = 0.2545, indicating increasing parallelism with increasing level of biological integration. The majority of pathways contained positively selected genes in both sulphide populations. Hence, adaptation to sulphidic habitats necessitated adjustments throughout the genome. The largely unique evolutionary trajectories may be explained by a high proportion of de novo mutations driving the divergence. Our findings favour Gould's view that evolution is often the unrepeatable result of stochastic events with highly contingent effects.
Assuntos
Adaptação Fisiológica/genética , Ecossistema , Evolução Molecular , Sulfeto de Hidrogênio/toxicidade , Poecilia/genética , Animais , Fluxo Gênico , Variação Genética , Genética Populacional , Polimorfismo de Nucleotídeo Único , Densidade Demográfica , Seleção Genética , Análise de Sequência de DNARESUMO
BACKGROUND: Fishes show an amazing diversity in hearing abilities, inner ear structures, and otolith morphology. Inner ear morphology, however, has not yet been investigated in detail in any member of the diverse order Cyprinodontiformes. We, therefore, studied the inner ear of the cyprinodontiform freshwater fish Poecilia mexicana by analyzing the position of otoliths in situ, investigating the 3D structure of sensory epithelia, and examining the orientation patterns of ciliary bundles of the sensory hair cells, while combining µ-CT analyses, scanning electron microscopy, and immunocytochemical methods. P. mexicana occurs in different ecotypes, enabling us to study the intra-specific variability (on a qualitative basis) of fish from regular surface streams, and the Cueva del Azufre, a sulfidic cave in southern Mexico. RESULTS: The inner ear of Poecilia mexicana displays a combination of several remarkable features. The utricle is connected rostrally instead of dorso-rostrally to the saccule, and the macula sacculi, therefore, is very close to the utricle. Moreover, the macula sacculi possesses dorsal and ventral bulges. The two studied ecotypes of P. mexicana showed variation mainly in the shape and curvature of the macula lagenae, in the curvature of the macula sacculi, and in the thickness of the otolithic membrane. CONCLUSIONS: Our study for the first time provides detailed insights into the auditory periphery of a cyprinodontiform inner ear and thus serves a basis--especially with regard to the application of 3D techniques--for further research on structure-function relationships of inner ears within the species-rich order Cyprinodontiformes. We suggest that other poeciliid taxa, or even other non-poeciliid cyprinodontiforms, may display similar inner ear morphologies as described here.