Survival of <i>Escherichia coli</i> under Nutrient-Deprived Conditions: Effect on Cell Envelope Subproteome

In the aquatic ecosystems, microorganisms are exposed to seasonal and circadian cycles. Abiotic factors (e.g. low temperature, nutrient deprivation) can cause morphological and physiological changes in bacteria, thereby facilitating cell survival. While representing the interface between the cells and external environment, the cell envelope plays a major role in bacterial response to stress and characterization of the changes it undergoes can help to understand the adaptation process. In this study, analysis of the morphological and physiological changes as well as variations in protein composition of the Escherichia coli cell envelope was carried out for populations maintained for 21 days under nutrient deprivation and suboptimal temperatures (4°C and 20°C). It was found that the absence of nutrients led to a temperature-dependent reduction of cell culturability but had no effect on cell viability and integrity. The concentration of membrane proteins playing the key roles in cellular transport, maintenance of cell structure or bioenergetics processes remained mainly unchanged. In contrast, the level of several proteins such as the elongation factor EFTu 1, components of Bam complex or proteins implicated in chemotaxis was altered, thus indicating that cells were readily responding and adapting to stress

Hepatic and Intestinal Multidrug Resistance-Associated Protein 2: Transcriptional and Post-transcriptional Regulation by Xenobiotics

We are daily exposed to a large number of pharmacological drugs, environmental pollutants, and natural toxins, which represent a potential toxic insult. The organism possesses a sophisticated system of detoxification particularly expressed in the liver, intestine, and kidney. This system consists of intracellular biotransformation enzymes that convert the toxins into more hydrophilic derivatives followed by their elimination through membrane transporters. Multidrug resistance-associated protein 2 (MRP2, ABCC2) is an important member of the ATP-binding cassette (ABC) superfamily of transporters localized at the apical membrane of polarized cells, such as hepatocytes, enterocytes, and renal tubular cells. MRP2 is proposed as a major actor in the elimination of endo- and xenobiotics, mainly conjugated with glucuronic acid, glutathione, and sulfate. The small intestine and the liver constitute relevant detoxification organs expressing MRP2 and therefore preventing absorption and promoting the hepatobiliary clearance of xenobiotics. MRP2 expression and/or function can be modulated by therapeutic drugs, herbal products, dietary compounds, and environmental pollutants. Consequently, MRP2 modulation could cause changes in tissue exposure, with potential toxicological and pharmacological consequences. This chapter reviews the information available on the role of hepatic and intestinal MRP2 in detoxification processes, and their regulation by xenobiotics, considering in particular its toxicological relevance

A influência de um campo magnético estático no escoamento sanguíneo com nanopartículas magnéticas

De forma a realizar estudos de escoamentos em microcanais e avaliar a influência das nanopartículas, sob a ação de um campo magnético estático, na espessura da camada de plasma, foram produzidas nanoparticulas de óxido de ferro por síntese solvotérmica, sendo posteriormente colocadas em suspensão num fluido fisiológico constituído por eritrócitos. Verificou-se que as nanopartículas com características magnéticas proporcionam a diminuição da espessura da camada de plasma, um comportamento contrário ao observado com nanopartículas sem características magnéticas.Os autores agradecem à FCT, COMPETE, QREN e União Europeia (FEDER) pelo financiamento através dos seguintes projetos: PTDC/SAU-BEB/105650/2008, PTDC/SAU-BEB/108728/2008, PTDC/EMEMFE/ 099109/2008, PEst-C/EQB/LA0020/2011 e PTDC/SAU-ENB/116929/2010

Sensory deprivation in Staphylococcus aureus

Bacteria use two-component systems (TCSs) to sense and respond to environmental changes. The core genome of the major human pathogen Staphylococcus aureus encodes 16 TCSs, one of which (WalRK) is essential. Here we show that S. aureus can be deprived of its complete sensorial TCS network and still survive under growth arrest conditions similarly to wild-type bacteria. Under replicating conditions, however, the WalRK system is necessary and sufficient to maintain bacterial growth, indicating that sensing through TCSs is mostly dispensable for living under constant environmental conditions. Characterization of S. aureus derivatives containing individual TCSs reveals that each TCS appears to be autonomous and self-sufficient to sense and respond to specific environmental cues, although some level of cross-regulation between non-cognate sensor-response regulator pairs occurs in vivo. This organization, if confirmed in other bacterial species, may provide a general evolutionarily mechanism for flexible bacterial adaptation to life in new niches.This work was supported by the Spanish Ministry of Economy and Competitiveness grants BIO2011-30503-C02-02, BIO2014-53530-R, SAF2014-56716-REDT, and RTC-2015-3184-1. J.V. was supported by Ramon y Cajal (RYC-2009-03948) contract from the Spanish Ministry of Economy and Competitiveness

The Effect of Visible Light on Cell Envelope Subproteome during Vibrio harveyi Survival at 20 °C in Seawater

A number of Vibrio spp. belong to the well-studied model organisms used to understand the strategies developed by marine bacteria to cope with adverse conditions (starvation, suboptimal temperature, solar radiation, etc.) in their natural environments. Temperature and nutrient availability are considered to be the key factors that influence Vibrio harveyi physiology, morphology, and persistence in aquatic systems. In contrast to the well-studied effects of temperature and starvation on Vibrio survival, little is known about the impact of visible light able to cause photooxidative stress. Here we employ V. harveyi ATCC 14126T as a model organism to analyze and compare the survival patterns and changes in the protein composition of its cell envelope during the long-term permanence of this bacterium in seawater microcosm at 20 °C in the presence and absence of illumination with visible light. We found that V. harveyi exposure to visible light reduces cell culturability likely inducing the entry into the Viable but Non Culturable state (VBNC), whereas populations maintained in darkness remained culturable for at least 21 days. Despite these differences, the starved cells in both populations underwent morphological changes by reducing their size. Moreover, further proteomic analysis revealed a number of changes in the composition of cell envelope potentially accountable for the different adaptation pattern manifested in the absence and presence of visible light

Nuevas cepas de Staphylococcus aureus y sus usos

[EN] Disclosed are mutant strains of Staphylococcus aureus with multiple inactivated TCS systems. The invention relates to mutant strains of S. aureus deprived of all non-essential two-component signal systems (TCSs) and even the essential WalKR system, to intermediate mutants deprived of a number of TCSs, and to the uses thereof as a research and biotechnology platform. The mutants deprived of all non-essential TCSs are viable, stable in laboratory growth conditions, genetically modifiable, and capable of expressing heterologous proteins. The mutants enable individual analysis of each TCS, the use thereof as a target, and individual complementation of same, and allow information concerning perception systems that can be used for biotechnology applications based on or directed to S. aureus, such as identifying new antimicrobials, to be obtained.[ES] Nuevas cepas de Staphylococcus aureus y sus usos. La invención proporciona cepas mutantes de S. aureus desprovistas de todos los sistemas de señales de dos componentes (TCSs) no esenciales e incluso del sistema esencial wal KR, los mutantes intermedios desprovistos de un número de TCSs y sus usos como plataforma de investigación y biotecnológica. Los mutantes desprovistos de todos los TCSs no esenciales son viables, estables en condiciones de crecimiento de laboratorio, genéticamente modificables y capaces de expresar proteínas heterólogas. Tenerlos permite el análisis individual y la utilización como diana de cada TCS, su complementación individual y obtener información sobre los sistemas de percepción que pueden ser útiles para aplicaciones biotecnológicas basadas en o dirigidas a S. aureus, tales como la identificación de nuevos antimicrobianos.Peer reviewedUniversidad Pública de Navarra, Consejo Superior de Investigaciones Científicas (España)E Solicitud de patente europe

Nuevas cepas de Staphylococcus aureus y sus usos

[EN] Disclosed are mutant strains of Staphylococcus aureus with multiple inactivated TCS systems. The invention relates to mutant strains of S. aureus deprived of all non-essential two-component signal systems (TCSs) and even the essential WalKR system, to intermediate mutants deprived of a number of TCSs, and to the uses thereof as a research and biotechnology platform. The mutants deprived of all non-essential TCSs are viable, stable in laboratory growth conditions, genetically modifiable, and capable of expressing heterologous proteins. The mutants enable individual analysis of each TCS, the use thereof as a target, and individual complementation of same, and allow information concerning perception systems that can be used for biotechnology applications based on or directed to S. aureus, such as identifying new antimicrobials, to be obtained.[ES] Nuevas cepas de Staphylococcus aureus y sus usos. La invención proporciona cepas mutantes de S. aureus desprovistas de todos los sistemas de señales de dos componentes (TCSs) no esenciales e incluso del sistema esencial wal KR, los mutantes intermedios desprovistos de un número de TCSs y sus usos como plataforma de investigación y biotecnológica. Los mutantes desprovistos de todos los TCSs no esenciales son viables, estables en condiciones de crecimiento de laboratorio, genéticamente modificables y capaces de expresar proteínas heterólogas. Tenerlos permite el análisis individual y la utilización como diana de cada TCS, su complementación individual y obtener información sobre los sistemas de percepción que pueden ser útiles para aplicaciones biotecnológicas basadas en o dirigidas a S. aureus, tales como la identificación de nuevos antimicrobianos.Peer reviewedUniversidad Pública de Navarra, Consejo Superior de Investigaciones Científicas (España)A1 Solicitud de patente con informe sobre el estado de la técnic

Analysis of Vibrio harveyi adaptation in sea water microcosms at elevated temperature provides insights into the putative mechanisms of its persistence and spread in the time of global warming

Discovering the means to control the increasing dissemination of pathogenic vibrios driven by recent climate change is challenged by the limited knowledge of the mechanisms in charge of Vibrio spp. persistence and spread in the time of global warming. To learn about physiological and gene expression patterns associated with the long-term persistence of V. harveyi at elevated temperatures, we studied adaptation of this marine bacterium in seawater microcosms at 30 °C which closely mimicked the upper limit of sea surface temperatures around the globe. We found that nearly 90% of cells lost their culturability and became partly damaged after two weeks, thus suggesting a negative impact of the combined action of elevated temperature and shortage of carbon on V. harveyi survival. Moreover, further gene expression analysis revealed that major adaptive mechanisms were poorly coordinated and apparently could not sustain cell fitness. On the other hand, elevated temperature and starvation promoted expression of many virulence genes, thus potentially reinforcing the pathogenicity of this organism. These findings suggest that the increase in disease outbreaks caused by V. harveyi under rising sea surface temperatures may not reflect higher cell fitness, but rather an increase in virulence enabling V. harveyi to escape from adverse environments to nutrient rich, host-pathogen associations.This work was supported by the Spanish Ministry of Economy and Competitiveness grant CGL2015-70929-R, Ikerbasque (Basque Foundation for Science) and pre-doctoral grants PRE-2013-1-901 (I.M.) from the Basque Government and PIF15/101 (E.O.) from the University of the Basque Country. A.E.-C. is funded by ISCIII of the MINECO (Ref: PT17/0009/0019) and cofinanced by FEDER

Analysis of Vibrio harveyi adaptation in sea water microcosms at elevated temperature provides insights into the putative mechanisms of its persistence and spread in the time of global warming

Discovering the means to control the increasing dissemination of pathogenic vibrios driven by recent climate change is challenged by the limited knowledge of the mechanisms in charge of Vibrio spp. persistence and spread in the time of global warming. To learn about physiological and gene expression patterns associated with the long-term persistence of V. harveyi at elevated temperatures, we studied adaptation of this marine bacterium in seawater microcosms at 30 °C which closely mimicked the upper limit of sea surface temperatures around the globe. We found that nearly 90% of cells lost their culturability and became partly damaged after two weeks, thus suggesting a negative impact of the combined action of elevated temperature and shortage of carbon on V. harveyi survival. Moreover, further gene expression analysis revealed that major adaptive mechanisms were poorly coordinated and apparently could not sustain cell fitness. On the other hand, elevated temperature and starvation promoted expression of many virulence genes, thus potentially reinforcing the pathogenicity of this organism. These findings suggest that the increase in disease outbreaks caused by V. harveyi under rising sea surface temperatures may not reflect higher cell fitness, but rather an increase in virulence enabling V. harveyi to escape from adverse environments to nutrient rich, host-pathogen associations.This work was supported by the Spanish Ministry of Economy and Competitiveness grant CGL2015-70929-R, Ikerbasque (Basque Foundation for Science) and pre-doctoral grants PRE-2013-1-901 (I.M.) from the Basque Government and PIF15/101 (E.O.) from the University of the Basque Country. A.E.-C. is funded by ISCIII of the MINECO (Ref: PT17/0009/0019) and cofinanced by FEDER

Análisis funcional de la regulación mediada por RNA antisentidos en Staphylococcus aureus

Póster presentado en el XXIII Congreso Nacional de Microbiología (SEM), celebrado en Salamanca del 11 al 14 de julio de 2011.Peer Reviewe