RESUMEN
Bioseston is a heterogeneous assemblage of bacterioplankton, phytoplankton, zooplankton, and planktonic debris. A detailed knowledge of biosestons is essential for understanding the dynamics of trophic flows in marine ecosystems. The distributional features of seston biomass in plankton (micro- and mesoplankton) in the Southwest Atlantic Ocean (Rio de Janeiro State, Brazil) were analyzed using stratified samples gathered to a depth of 2,400 m during night time. The horizontal pattern of biomass distribution was analyzed vis-a-vis station depth during both wet and dry periods, with higher values recorded in the continental shelf than in the slope, confirming the terrestrial contribution of nutrient sources to the marine environment. This horizontal variation reinforces the occurrence of seasonal vortices in Cabo Frio and Cabo de São Tomé on the central coast of Brazil. Environmental variables reflect the hydrological signatures of the water masses along the Brazilian coast. The largest seston biomass was related to high temperatures, salinities, and low inorganic nutrient concentrations in tropical and South Atlantic central waters. The observed distribution patterns suggest that seston biomass in plankton in the region may be structured based on partitioned horizontal and vertical habitats and food resources.
Asunto(s)
Biomasa , Plancton , Estaciones del Año , Océano Atlántico , Brasil , Plancton/crecimiento & desarrollo , Plancton/clasificación , Plancton/fisiología , Animales , Ecosistema , Fitoplancton/clasificación , Fitoplancton/crecimiento & desarrollo , Fitoplancton/fisiología , Análisis Espacio-TemporalRESUMEN
Biofilms are important to the virulence of human pathogenic fungi, and some molecules have been found to play key roles in the growth and regulation of fungal biofilms. Farnesol, one of these molecules, is well-described for some microorganisms but is still scarcely known for Rhodotorula spp. This study aimed to evaluate the influence of farnesol on the biofilm of R. mucilaginosa. Initially, screening with 0.2 mM to 2.1 mM of farnesol was evaluated against planktonic forms. A concentration of this compound was then chosen and evaluated for its effect on biofilm in formation and on preformed biofilm after 24, 48 and 72 hours. The impact of farnesol was evaluated by colony-forming units (CFU) counts, determination of metabolic activity and quantification of total biomass. In the presence of 0.9 mM, farnesol was able to decrease the CFU number, at 48 hours, when the biofilm was in formation, although it did not affect the preformed biofilms. Thus, our results show that farnesol exerts a modulating activity during biofilm formation for R. mucilaginosa, with this compound reducing the metabolic activity and total biomass of the biofilms.
Asunto(s)
Farnesol , Rhodotorula , Biopelículas , Farnesol/farmacología , Humanos , Plancton/fisiologíaRESUMEN
Evidence indicates that migratory fish reproduce in the middle Uruguay River, but the location of spawning sites remains unknown. To identify spawning sites in the basin, fish eggs and larvae were sampled monthly between October 2016 and January 2017. The sampling was carried out in three sections along the middle Uruguay River, covering two environments: the main channel and the mouth of tributaries (Comandaí, Ijuí, and Piratinim rivers). A total of 11,519 eggs and 3,211 larvae were captured, belonged to ten migratory species. Eggs and larvae of migratory fishes, were widely distributed, with predominance of segmented eggs, and larvae in yolk-sac and pre-flexion stages, with higher densities near the confluence with the Piratinim River. Larvae assemblages showed spatial variation, indicating that spawning sites differ among migratory species. This study provides new information about fish reproduction in the middle Uruguay River, revealing that migratory species spawn in different localities along the main channel and tributaries. This region may function as a critical site for fish reproduction, although it is currently threatened by the risk of hydropower expansion, emphasizing the need for measures that preserve their environmental conditions, hydrological connectivity and ecological functions.(AU)
Evidências indicam que os peixes migradores se reproduzem no médio rio Uruguai, mas a localização dos locais de desova ainda permanece desconhecida. Para identificar estes locais, foram realizadas mensalmente entre outubro de 2016 e janeiro de 2017, amostragens de ovos e larvas de peixes em três seções ao longo do médio rio Uruguai, cobrindo dois ambientes: o canal principal e a foz dos afluentes (rios Comandaí, Ijuí e Piratinim). Foram capturados 11.519 ovos e 3.211 larvas, pertencentes a dez espécies migradoras. Ovos e larvas de peixes migradores, foram amplamente distribuídos, com predomínio de ovos segmentados e larvas em estágios de larval-vitelino e pré-flexão, com maiores densidades próximo à confluência com o rio Piratinim. As assembleias de larvas mostraram variação espacial, indicando que os locais de desova diferem entre as espécies migradoras. Este estudo fornece novas informações sobre a reprodução de peixes no médio rio Uruguai, revelando que espécies migradoras desovam em diferentes localidades ao longo do canal principal e afluentes. Esta região pode funcionar como um local crítico para a reprodução de peixes, embora atualmente esteja ameaçada pelo risco de expansão da energia hidrelétrica, enfatizando a necessidade de medidas que preservem suas condições ambientais, conectividade hidrológica e funções ecológicas.(AU)
Asunto(s)
Plancton/fisiología , Migración Animal/fisiología , Peces , BrasilRESUMEN
Humans live in symbiosis with a diverse community of microorganisms, which has evolved to carry out many specific tasks that benefit the host, including protection against invading pathogens. Within the chemical diversity of the gastrointestinal tract, small molecules likely constitute chemical cues for the communication between the microbiota and pathogens. Therefore, we sought to investigate if molecules produced by the human gut microbiota show biological activity against the human pathogen Vibrio cholerae. To probe the effects of the gut metabolome on V. cholerae, we investigated its response to small-molecule extracts from human feces, from a complex bacterial community cultivated in vitro, and from culture supernatants of Enterocloster citroniae, Bacteroides thetaiotaomicron, and Bacteroides vulgatus. Using RNA sequencing, we determined the impact of the human gut metabolome on V. cholerae global gene expression. Among the genes downregulated in the presence of the fecal extract, the most overrepresented functional category was cell motility, which accounted for 39% of repressed genes. Repression of V. cholerae motility by the fecal extract was confirmed phenotypically, and E. citroniae extracts reproduced this phenotype. A complex in vitro microbial community led to increased motility, as did extracts from B. vulgatus, a species present in this community. Accordingly, mucin penetration was also repressed by fecal and E. citroniae extracts, suggesting that the phenotypes observed may have implications for host colonization. Together with previous studies, this work shows that small molecules from the gut metabolome may have a widespread, significant impact on microbe-microbe interactions established in the gut environment.
Asunto(s)
Bacterias/química , Bacterias/metabolismo , Microbioma Gastrointestinal , Metaboloma , Vibrio cholerae/crecimiento & desarrollo , Adulto , Bacterias/clasificación , Bacterias/genética , Heces/química , Heces/microbiología , Femenino , Regulación Bacteriana de la Expresión Génica , Humanos , Interacciones Microbianas , Plancton/genética , Plancton/fisiología , Vibrio cholerae/genética , Vibrio cholerae/fisiologíaRESUMEN
Following the appearance of several antimicrobial agents to control the spread of infections, two major challenges have emerged: (i) the occurrence and blowout of multiresistant bacteria and the increase of chronic diseases and (ii) difficult-to-eradicate infections. In this study, we tested five benzoylthiourea derivatives for their ability to inhibit and stop bacterial growth and evaluated the possible influence of 1,2,4-triazolyl-benzoylthiourea derivative 4 on the formation and eradication of Staphylococcus aureus biofilms. Benzoylthiourea derivatives 4, 6, 10, 11 and 13 were obtained in one or two steps with low cost and subjected to tests to identify their minimum inhibitory concentration (MIC) and minimum bactericidal concentration. In vitro tests were also performed to assess their effects on biofilm formation and in preformed biofilms and scanning electron microscopy was used to visualize the effects on biofilm formation. The 1,2,4-triazolyl-benzoylthiourea derivative 4 showed bacteriostatic activity against the S. aureus HU25 clinical strain with an MIC of 16 µg ml-1 , which is below the toxic concentration (at 2500 µg ml-1 , 62·25% of the cells remained viable). Compound 4 also effectively prevented biofilm formation at the three subinhibitory concentrations tested (1/2 MIC, 1/4 MIC and 1/8 MIC) as confirmed by scanning electron microscopy. For breakdown of formed biofilms, the main influence was at a subinhibitory concentration (1/2 MIC). These findings make compound 4 a strong candidate for studies on the development of new antimicrobial and antibiofilm agents.
Asunto(s)
Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Tiourea/farmacología , Antibacterianos/síntesis química , Antibacterianos/química , Humanos , Pruebas de Sensibilidad Microbiana , Plancton/efectos de los fármacos , Plancton/crecimiento & desarrollo , Plancton/fisiología , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/crecimiento & desarrollo , Staphylococcus aureus/fisiología , Tiourea/químicaRESUMEN
Microbial communities within oxygen minimum zones (OMZs) are crucial drivers of marine biogeochemical cycles; however, we still lack an understanding of how these communities are distributed across an OMZ. We explored vertical (from 5 to 500 m depth) and horizontal (coast to open ocean) distribution of bacterioplankton and its relationships with the main oceanographic conditions in three transects of the tropical Mexican Pacific OMZ. The distribution of the microbial diversity and the main clades changed along the transition from oxygen-rich surface water to the OMZ core, demonstrating the sensitivity of key bacterial groups to deoxygenation. The euphotic zone was dominated by Synechococcales, followed by Flavobacteriales, Verrucomicrobiales, Rhodobacterales, SAR86, and Cellvibrionales, whereas the OMZ core was dominated by SAR11, followed by SAR406, SAR324, SAR202, UBA10353 marine group, Thiomicrospirales and Nitrospinales. The marked environmental gradients along the water column also supported a high potential for niche partitioning among OMZ microorganisms. Additionally, in the OMZ core, bacterial assemblages from the same water mass were more similar to each other than those from another water mass. There were also important differences between coastal and open-ocean communities: Flavobacteriales, Verrucomicrobiales, Rhodobacterales, SAR86, and Cellvibrionales were more abundant in coastal areas, while Synechococcales, SAR406, SAR324, SAR202, UBA10353 marine group, and Thiomicrospirales were more abundant in the open ocean. Our results suggest a biogeographic structure of the bacterioplankton in this OMZ region, with limited community mixing across water masses, except in upwelling events, and little dispersion of the community by currents in the euphotic zone.
Asunto(s)
Fenómenos Fisiológicos Bacterianos , Microbiota/fisiología , Plancton/fisiología , Agua de Mar/microbiología , México , Oxígeno/análisis , Océano Pacífico , Clima TropicalRESUMEN
Guanabara Bay is a tropical estuarine ecosystem that receives massive anthropogenic impacts from the metropolitan region of Rio de Janeiro. This ecosystem suffers from an ongoing eutrophication process that has been shown to promote the emergence of potentially pathogenic bacteria, giving rise to public health concerns. Although previous studies have investigated how environmental parameters influence the microbial community of Guanabara Bay, they often have been limited to small spatial and temporal gradients and have not been integrated into predictive mathematical models. Our objective was to fill this knowledge gap by building models that could predict how temperature, salinity, phosphorus, nitrogen and transparency work together to regulate the abundance of bacteria, chlorophyll and Vibrio (a potential human pathogen) in Guanabara Bay. To that end, we built artificial neural networks to model the associations between these variables. These networks were carefully validated to ensure that they could provide accurate predictions without biases or overfitting. The estimated models displayed high predictive capacity (Pearson correlation coefficients ≥0.67 and root mean square errorâ¯≤â¯0.55). Our findings showed that temperature and salinity were often the most important factors regulating the abundance of bacteria, chlorophyll and Vibrio (absolute importance ≥5) and that each of these has a unique level of dependence on nitrogen and phosphorus for their growth. These models allowed us to estimate the Guanabara Bay microbiome's response to changes in environmental conditions, which allowed us to propose strategies for the management and remediation of Guanabara Bay.
Asunto(s)
Monitoreo del Ambiente/métodos , Microbiota/fisiología , Redes Neurales de la Computación , Plancton/fisiología , Bahías/química , Bahías/microbiología , Brasil , Modelos BiológicosRESUMEN
Foodborne microbial diseases are still considered a growing public health problem worldwide despite the global continuous efforts to ensure food safety. The traditional chemical and thermal-based procedures applied for microbial growth control in the food industry can change the food matrix and lead to antimicrobial resistance. Moreover, currently applied disinfectants have limited efficiency against biofilms. Therefore, antimicrobial photodynamic therapy (aPDT) has become a novel alternative for controlling foodborne pathogenic bacteria in both planktonic and sessile states. The use of aPDT in the food sector is attractive as it is less likely to cause antimicrobial resistance and it does not promote undesirable nutritional and sensory changes in the food matrix. In this review, aspects on the antimicrobial photodynamic technology applied against foodborne pathogenic bacteria and studied in recent years are presented. The application of photodynamic inactivation as an antibiofilm strategy is also reviewed.
Asunto(s)
Bacterias/efectos de la radiación , Infecciones Bacterianas/terapia , Fotoquimioterapia , Plancton/efectos de la radiación , Animales , Bacterias/efectos de los fármacos , Bacterias/genética , Infecciones Bacterianas/microbiología , Fenómenos Fisiológicos Bacterianos/efectos de los fármacos , Fenómenos Fisiológicos Bacterianos/efectos de la radiación , Biopelículas/efectos de los fármacos , Biopelículas/efectos de la radiación , Humanos , Fármacos Fotosensibilizantes/farmacología , Plancton/efectos de los fármacos , Plancton/genética , Plancton/fisiologíaRESUMEN
Background: : There is evidence that drinking water could be a source of infections with pathogenic nontuberculous mycobacteria (NTM) potentially risky to human health. The aim was to investigate the resistance of two NTM isolated from drinking water, Mycobacterium gordonae and Mycobacterium chubuense, at different concentrations of chlorine (as sodium hypochlorite), used in drinking water sanitation. Methods: : The NTM were grown in suspension and in biofilms and were challenged with biocide for 10 and 60 min. Results: To obtain 7-log reduction from the initial population of M. chubuense, in the planktonic state, there were necessary 20 ppm of chorine and 60 min of exposure. The same effect was achieved in M. gordonae with 10 ppm for the same period. The maximum reduction of both NTM in biofilm was 3-log reduction and was achieved using 30 ppm for 60 min. The chlorine susceptibility of cells in biofilms was significantly lower than that of planktonic cells. The results highlight the resistance of both NTM to the concentrations used in routine water sanitation (0.2 ppm according to Argentine Food Code). Differences in chlorine resistance found between the two NTM in planktonic growth decrease when they are grown in biofilm. Conclusion: This suggests that current water disinfection procedures do not always achieve effective control of NTM in the public supply system, with the consequent health risk to susceptible population, and the need to take into account biofilms, because of their deep consequences in the way to analyze the survival of prokaryotic cells in different environments.
Asunto(s)
Biopelículas/efectos de los fármacos , Desinfectantes/farmacología , Mycobacterium/efectos de los fármacos , Micobacterias no Tuberculosas/efectos de los fármacos , Hipoclorito de Sodio/farmacología , Desinfección , Mycobacterium/crecimiento & desarrollo , Mycobacterium/fisiología , Micobacterias no Tuberculosas/crecimiento & desarrollo , Micobacterias no Tuberculosas/fisiología , Plancton/efectos de los fármacos , Plancton/fisiologíaRESUMEN
The present study aimed to investigate the inhibitory effect of a bacterial biosurfactant (TIM96) on clinical strains of Trichosporon. Additionally, the effect of TIM96 on the ergosterol content, cell membrane integrity, and the hydrophobicity of planktonic cells was assessed. The inhibitory activity of TIM96 against Trichosporon biofilms was evaluated by analyzing metabolic activity, biomass and morphology. MIC values ranged from 78.125 to 312.5 µg ml-1 for TIM96; time-kill curves revealed that the decline in the number of fungal cells started after incubation for 6 h with TIM96 at both MIC and 2×MIC. The biosurfactant reduced the cellular ergosterol content and altered the membrane permeability and the surface hydrophobicity of planktonic cells. Incubation at 10×MIC TIM96 reduced cell adhesion by up to 96.89%, thus interfering with biofilm formation. This concentration also caused up to a 99.2% reduction in the metabolic activity of mature biofilms. The results indicate potential perspectives for the development of new antifungal strategies.
Asunto(s)
Antifúngicos/farmacología , Bacillus subtilis/metabolismo , Adhesión Celular/efectos de los fármacos , Lipopéptidos/farmacología , Trichosporon/efectos de los fármacos , Antifúngicos/metabolismo , Biopelículas/crecimiento & desarrollo , Lipopéptidos/biosíntesis , Plancton/efectos de los fármacos , Plancton/metabolismo , Plancton/fisiología , Tensoactivos/farmacología , Trichosporon/metabolismo , Trichosporon/fisiologíaRESUMEN
AIM: To synthesize, characterize and evaluate the antimicrobial and antibiofilm activities of novel nanocomposites containing silver nanoparticles (AgNPs) associated or not to ß-calcium glycerophosphate. MATERIALS & METHODS: These nanocomposites were produced through a 'green' route using extracts of different parts of pomegranate. Antimicrobial and antibiofilm properties against Candida albicans and Streptococcus mutans were determined by the minimum bactericidal/fungicidal concentration and biofilm density after treatments. RESULTS: All extracts used were successful in producing AgNPs. Composites made with peel extracts showed the highest antimicrobial and antibiofilm activity against both microorganisms tested and performed similarly or even better than chlorhexidine. CONCLUSION: AgNPs associated or not to calcium glycerophosphate produced by a 'green' process may be a promising novel antimicrobial agent against oral microorganisms.
Asunto(s)
Antiinfecciosos/farmacología , Biopelículas/efectos de los fármacos , Candida albicans/efectos de los fármacos , Glicerofosfatos/química , Nanopartículas del Metal/química , Nanocompuestos/química , Plata/farmacología , Streptococcus mutans/efectos de los fármacos , Antiinfecciosos/química , Clorhexidina/farmacología , Humanos , Lythraceae/química , Nanocompuestos/microbiología , Plancton/efectos de los fármacos , Plancton/fisiología , Extractos Vegetales/química , Hojas de la Planta/química , Semillas/química , Plata/químicaRESUMEN
AIM: This study examined the antifungal activity of the combination of tyrosol and farnesol against Candida albicans and Candida glabrata in the planktonic state or forming biofilms. METHODS AND RESULTS: The effect of drug association against Candida planktonic cells was assessed by the fractional inhibitory concentration index. Mono- and dual-species biofilms were developed during 24 h and then treated with the compounds for 3 days, with two daily treatments of 1 min each. After, the total biomass, metabolic activity and the number of cultivable cells were quantified. Planktonic cells of the two species showed a similar susceptibility to the drug combination, however, a synergistic effect was only verified for C. glabrata. Regarding biofilm susceptibility, significant reductions in C. glabrata biomass, metabolism of C. albicans and mixed biofilms, and cultivable cells of single biofilms were verified for the drug combination, indicating an additive effect. For all other experiments, the effects were classified as indifferent. CONCLUSION: The combined use of tyrosol and farnesol was advantageous for some of the analysed parameters against Candida species. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings may contribute to the development of oral care products containing tyrosol and farnesol to combat oral infections caused by Candida species.
Asunto(s)
Antifúngicos/farmacología , Biopelículas/efectos de los fármacos , Candida albicans/efectos de los fármacos , Candida glabrata/efectos de los fármacos , Farnesol/farmacología , Alcohol Feniletílico/análogos & derivados , Plancton/efectos de los fármacos , Candida albicans/genética , Candida albicans/fisiología , Candida glabrata/genética , Candida glabrata/fisiología , Sinergismo Farmacológico , Pruebas de Sensibilidad Microbiana , Alcohol Feniletílico/farmacología , Plancton/genética , Plancton/fisiologíaRESUMEN
Determining statistical patterns irrespective of interacting agents (i.e. macroecology) is useful to explore the mechanisms driving population fluctuations and extinctions in natural food webs. Here, we tested four predictions of a neutral model on the distribution of community fluctuations (CF) and the distributions of persistence times (APT). Novel predictions for the food web were generated by combining (1) body size-density scaling, (2) Taylor's law and (3) low efficiency of trophic transference. Predictions were evaluated on an exceptional data set of plankton with 15 years of weekly samples encompassing c. 250 planktonic species from three trophic levels, sampled in the western English Channel. Highly symmetric non-Gaussian distributions of CF support zero-sum dynamics. Variability in CF decreased while a change from an exponential to a power law distribution of APT from basal to upper trophic positions was detected. Results suggest a predictable but profound effect of trophic position on fluctuations and extinction in natural communities.
Asunto(s)
Extinción Biológica , Cadena Alimentaria , Plancton/fisiología , Inglaterra , Modelos Biológicos , Océanos y Mares , Dinámica PoblacionalRESUMEN
Copepods are aquatic microcrustaceans and represent the most abundant metazoans on Earth, outnumbering insects and nematode worms. Their position of numerical world predominance can be attributed to three principal radiation events, i.e. their major habitat shift into the marine plankton, the colonization of freshwater and semiterrestrial environments, and the evolution of parasitism. Their variety of life strategies has generated an incredible morphological plasticity and disparity in body form and shape that are arguably unrivalled among the Crustacea. Although their chitinous exoskeleton is largely resistant to chemical degradation copepods are exceedingly scarce in the geological record with limited body fossil evidence being available for only three of the eight currently recognized orders. The preservation of aquatic arthropods in amber is unusual but offers a unique insight into ancient subtropical and tropical ecosystems. Here we report the first discovery of amber-preserved harpacticoid copepods, represented by ten putative species belonging to five families, based on Early Miocene (22.8 million years ago) samples from Chiapas, southeast Mexico. Their close resemblance to Recent mangrove-associated copepods highlights the antiquity of the specialized harpacticoid fauna living in this habitat. With the taxa reported herein, the Mexican amber holds the greatest diversity of fossil copepods worldwide.
Asunto(s)
Ámbar , Copépodos/fisiología , Fósiles , Plancton/fisiología , Animales , Evolución Biológica , Ecosistema , México , Simbiosis , HumedalesRESUMEN
AIM: This study aims to understand which Candida orthopsilosis protein aids fungus adaptation upon its switching from planktonic growth to biofilm. MATERIALS & METHODS: Ion mobility separation within mass spectrometry analysis combination were used. RESULTS: Proteins mapped for different biosynthetic pathways showed that selective ribosome autophagy might occur in biofilms. Glucose, used as a carbon source in the glycolytic flux, changed to glycogen and trehalose. CONCLUSION: Candida orthopsilosis expresses proteins that combine a variety of mechanisms to provide yeasts with the means to adjust the catalytic properties of enzymes. Adjustment of the enzymes helps modulate the biosynthesis/degradation rates of the available nutrients, in order to control and coordinate the metabolic pathways that enable cells to express an adequate response to nutrient availability.
Asunto(s)
Biopelículas/crecimiento & desarrollo , Candida/metabolismo , Candida/fisiología , Metaboloma/fisiología , Plancton/crecimiento & desarrollo , Aminoácidos/biosíntesis , Aminoácidos/genética , Candida/genética , Candida/crecimiento & desarrollo , Carbono/metabolismo , Ciclo del Ácido Cítrico , Proteínas Fúngicas/biosíntesis , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/fisiología , Regulación Fúngica de la Expresión Génica/genética , Regulación Fúngica de la Expresión Génica/fisiología , Ontología de Genes , Glucosa/metabolismo , Glucógeno/metabolismo , Glucólisis , Análisis de Flujos Metabólicos , Redes y Vías Metabólicas/genética , Redes y Vías Metabólicas/fisiología , Metaboloma/genética , Familia de Multigenes , Plancton/metabolismo , Plancton/fisiología , Proteoma/genética , Proteoma/metabolismo , Proteoma/fisiología , Trehalosa/metabolismoRESUMEN
Changes of the plankton community in a shallow, subtropical lagoonal system and its relation to environmental conditions were investigated during an annual cycle to provide information on its spatial and seasonal variation pattern. The study carried out at four sites (three in the Peixe lagoon and one in the Ruivo lagoon), which are located in the Lagoa do Peixe National Park, southern Brazil. The system has a temporary connection to the Atlantic Ocean by a narrow channel. The phytoplankton density was higher in the Peixe lagoon whereas the specific richness was higher in the Ruivo lagoon which is also a site with the lower salinity. The phytoplankton biomass near the channel showed seasonal variation with the highest value in fall and lowest in winter. Zooplankton richness was inversely correlated with salinity, and had the highest values in the Ruivo lagoon. Ordination analysis indicated seasonal and spatial patterns in plankton community in this lagoonal system, related to variation in salinity. In addition, the wind action and precipitation were important factors on the spatial and seasonal salinity changes in the lagoon with direct influence on the plankton community dynamics.
Asunto(s)
Biomasa , Plancton/clasificación , Brasil , Plancton/fisiología , Densidad de Población , Dinámica Poblacional , Estaciones del AñoRESUMEN
The generation of a new antifungal against Candida albicans biofilms has become a major priority, since biofilm formation by this opportunistic pathogenic fungus is usually associated with an increased resistance to azole antifungal drugs and treatment failures. Miltefosine is an alkyl phospholipid with promising antifungal activity. Here, we report that, when tested under planktonic conditions, miltefosine displays potent in vitro activity against multiple fluconazole-susceptible and -resistant C. albicans clinical isolates, including isolates overexpressing efflux pumps and/or with well-characterized Erg11 mutations. Moreover, miltefosine inhibits C. albicans biofilm formation and displays activity against preformed biofilms. Serial passage experiments confirmed that miltefosine has a reduced potential to elicit resistance, and screening of a library of C. albicans transcription factor mutants provided additional insight into the activity of miltefosine against C. albicans growing under planktonic and biofilm conditions. Finally, we demonstrate the in vivo efficacy of topical treatment with miltefosine in the murine model of oropharyngeal candidiasis. Overall, our results confirm the potential of miltefosine as a promising antifungal drug candidate, in particular for the treatment of azole-resistant and biofilm-associated superficial candidiasis.
Asunto(s)
Antifúngicos/farmacología , Biopelículas/efectos de los fármacos , Candida albicans/efectos de los fármacos , Candidiasis Bucal/tratamiento farmacológico , Fosforilcolina/análogos & derivados , Plancton/efectos de los fármacos , Animales , Biopelículas/crecimiento & desarrollo , Candida albicans/genética , Candida albicans/crecimiento & desarrollo , Candida albicans/metabolismo , Candidiasis Bucal/microbiología , Candidiasis Bucal/patología , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismo , Farmacorresistencia Fúngica/genética , Fluconazol/farmacología , Expresión Génica , Ratones , Pruebas de Sensibilidad Microbiana , Mutación , Fosforilcolina/farmacología , Plancton/fisiología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Resultado del TratamientoRESUMEN
Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole.