Structure and application of antifreeze proteins from Antarctic bacteria

Indexación: Web of Science; Scopus.Background: Antifreeze proteins (AFPs) production is a survival strategy of psychrophiles in ice. These proteins have potential in frozen food industry avoiding the damage in the structure of animal or vegetal foods. Moreover, there is not much information regarding the interaction of Antarctic bacterial AFPs with ice, and new determinations are needed to understand the behaviour of these proteins at the water/ice interface. Results: Different Antarctic places were screened for antifreeze activity and microorganisms were selected for the presence of thermal hysteresis in their crude extracts. Isolates GU1.7.1, GU3.1.1, and AFP5.1 showed higher thermal hysteresis and were characterized using a polyphasic approach. Studies using cucumber and zucchini samples showed cellular protection when samples were treated with partially purified AFPs or a commercial AFP as was determined using toluidine blue O and neutral red staining. Additionally, genome analysis of these isolates revealed the presence of genes that encode for putative AFPs. Deduced amino acids sequences from GU3.1.1 (gu3A and gu3B) and AFP5.1 (afp5A) showed high similarity to reported AFPs which crystal structures are solved, allowing then generating homology models. Modelled proteins showed a triangular prism form similar to β-helix AFPs with a linear distribution of threonine residues at one side of the prism that could correspond to the putative ice binding side. The statistically best models were used to build a protein-water system. Molecular dynamics simulations were then performed to compare the antifreezing behaviour of these AFPs at the ice/water interface. Docking and molecular dynamics simulations revealed that gu3B could have the most efficient antifreezing behavior, but gu3A could have a higher affinity for ice. Conclusions: AFPs from Antarctic microorganisms GU1.7.1, GU3.1.1 and AFP5.1 protect cellular structures of frozen food showing a potential for frozen food industry. Modeled proteins possess a β-helix structure, and molecular docking analysis revealed the AFP gu3B could be the most efficient AFPs in order to avoid the formation of ice crystals, even when gu3A has a higher affinity for ice. By determining the interaction of AFPs at the ice/water interface, it will be possible to understand the process of adaptation of psychrophilic bacteria to Antarctic ice.https://microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0737-

Formulation effects on the lubricity of o/w emulsions used as oil well working fluids

In oil well drilling, completion, and maintenance operations, the rotating pipe bears against the side of the hole at numerous points, giving rise to two main friction manifestations known as torque and drag. Torque refers to the pipe resistance to rotation and drag to hoisting and lowering. Excessive torque and drag can cause unacceptable loss of power making oil well operations less efficient, especially in high-angle and extended-reach wells. In these cases, lubricity becomes one of the main functions of the fluid. In the oil industry, there are oil well working fluids of different nature, classified according to the external phase as water-based fluids (WBFs), oil-based fluids, and pneumatic or gas-based fluid systems. Within WBFs, there are oil-in-water (O/W) emulsions, developed as a technological solution for oil well operations in low-pressure reservoirs. In this work, tribological properties of O/W emulsions have been studied as a function of their physicochemical formulation, especially oil type (nonaromatic mineral oil [NAM-oil], diesel) and surfactant concentration (1, 2% w/v) along with the oil/water ratio (70/30, 50/50) as formulation variables. The lubrication performance was established by measuring the coefficient of friction (CF), and optical microscopy imaging in conjunction with optical surface profilometry was used to evaluate antiwear properties. Additionally, contact angle measurements were performed to correlate the wettability phenomenon with the lubricity of O/W emulsions. Based on the results, it was established that with the surfactants mixture used in this study, the oil type does not have a significant effect on the CF of O/W emulsions, due to the similar wettability behavior observed at the metal surface. However, NAM-oil/W emulsions have better antiwear properties than the diesel/W emulsions. Also, the lubricity performance and antiwear properties of O/W emulsions are affected by oil/water ratio and surfactants mixture concentration, showing a systemic interaction between these two parameters

Formulation effects on the lubricity of o/w emulsions used as oil well working fluids

In oil well drilling, completion, and maintenance operations, the rotating pipe bears against the side of the hole at numerous points, giving rise to two main friction manifestations known as torque and drag. Torque refers to the pipe resistance to rotation and drag to hoisting and lowering. Excessive torque and drag can cause unacceptable loss of power making oil well operations less efficient, especially in high-angle and extended-reach wells. In these cases, lubricity becomes one of the main functions of the fluid. In the oil industry, there are oil well working fluids of different nature, classified according to the external phase as water-based fluids (WBFs), oil-based fluids, and pneumatic or gas-based fluid systems. Within WBFs, there are oil-in-water (O/W) emulsions, developed as a technological solution for oil well operations in low-pressure reservoirs. In this work, tribological properties of O/W emulsions have been studied as a function of their physicochemical formulation, especially oil type (nonaromatic mineral oil [NAM-oil], diesel) and surfactant concentration (1, 2% w/v) along with the oil/water ratio (70/30, 50/50) as formulation variables. The lubrication performance was established by measuring the coefficient of friction (CF), and optical microscopy imaging in conjunction with optical surface profilometry was used to evaluate antiwear properties. Additionally, contact angle measurements were performed to correlate the wettability phenomenon with the lubricity of O/W emulsions. Based on the results, it was established that with the surfactants mixture used in this study, the oil type does not have a significant effect on the CF of O/W emulsions, due to the similar wettability behavior observed at the metal surface. However, NAM-oil/W emulsions have better antiwear properties than the diesel/W emulsions. Also, the lubricity performance and antiwear properties of O/W emulsions are affected by oil/water ratio and surfactants mixture concentration, showing a systemic interaction between these two parameters

Is there a pre-Cretaceous source rock in the Colombia Putumayo Basin? Clues from a study of crude oils by conventional and high resolution geochemical methods

A geochemical characterization of sixteen crude oil samples from the Putumayo Basin, southern Colombia, was carried out. This basin is located to the north of Ecuador’s Oriente Basin, one of the most prolific hydrocarbon basins in South America. Regardless of the fact that these two basins seem to share the same geological evolution, the volume of hydrocarbon reserves found in the Oriente Basin is five times greater than in the Putumayo Basin. This represents an exploratory opportunity to the extent that a better understanding of the petroleum system processes in the Putumayo Basin can be achieved. Newly available geochemical technology shows evidence that these crude oils originated from Late Cretaceous source rocks. The novel application of an age-related biomarker, the C25- highly branched isoprenoid, has constrained the age of the principal source of all these oils as Late Cretaceous or younger. Advanced geochemical technologies, such as compound specific isotope analyses of biomarkers (CSIA-B) and diamondoids (CSIA-D), and quantitative extended diamondoid analysis (QEDA), have confirmed, repeatedly, that the oil samples are all related to the same source with minor facies variations. The integration of these results with geological data suggests the presence of a very efficient petroleum system, characterized by an alternating sequence of soçurce and reservoir rocks. Thermal maturity of the oils from biomarker and diamondoid parameters ranges from well before the peak of hydrocarbon expulsion to the beginning of the late hydrocarbon generation phase. The aerial distribution of these maturity parameters suggests the existence of two, or possibly three, pods of active source rocks, located to the southwest and to the east of the basin, and possibly to the north. This would modify the classic hydrocarbon migration model for the Putumayo Basin, increasing the hydrocarbon potential of the basin. Given the low level of thermal maturity documented in the Cretaceous sequence that has been drilled, the possibility to evaluate the presence of a very reactive kerogen with hydrocarbon expulsion thresholds at lower temperatures is proposed

MgO-mediated activation of active carbon as an affordable strategy to “in situ” degradation of lindane in contaminated soils

The accumulation in soil landfills of toxic and persistent lindane, widely used as an insecticide, triggers the risk of leaching with the concomitant contamination of surrounding rivers. Thus, viable remediation to eliminate in situ high concentrations of lindane in soil and water becomes an urgent demand. In this line, a simple and costeffective composite is proposed, including the use of industrial wastes. It includes reductive and non-reductive base-catalyzed strategies to remove lindane in the media. A mixture of magnesium oxide (MgO) and activated carbon (AC) was selected for that purpose. The use of MgO provides a basic pH. In addition, the specific selected MgO forms double-layered hydroxides in water which permits the total adsorption of the main heavy metals in contaminated soils. AC provides adsorption microsites to hold the lindane and a reductive atmosphere that was increased when combined with the MgO. These properties trigger highly efficient remediation of the composite. It permits a complete elimination of lindane in the solution. In soils doped with lindane and heavy metals, it produces a rapid, complete, and stable elimination of lindane and immobilization of the metals. Finally, the composite tested in lindane-highly contaminated soils permits the “in situ” degradation of nearly 70% of the initial lindane. The proposed strategy opens a promising way to face this environmental issue with a simple, costeffective composite to degrade lindane and fix heavy metals in contaminated soils

Relative importance of environment, human activity and spatial situation in determining the distribution of terrestrial mammal diversity in Argentina

We recorded the number of terrestrial mammal species in each Argentinian province, and the number of species belonging to particular groups (Marsupialia, Placentaria, and among the latter, Xenarthra, Carnivora, Ungulates and Rodentia). We performed multiple regressions of each group’s SR on environmental, human and spatial variables, to determine the amounts of variation explained by these factors. We then used a variance partitioning procedure to specify which proportion of the variation in SR is explained by each of the three factors exclusively and which proportions are attributable to interactions between factors

Geographical gradients in Argentinean terrestrial mammal species richness and their environmental correlates.

We analysed the main geographical trends of terrestrial mammal species richness (SR) in Argentina, assessing how broad-scale environmental variation (defined by climatic and topographic variables) and the spatial form of the country (defined by spatial filters based on spatial eigenvector mapping (SEVM)) influence the kinds and the numbers of mammal species along these geographical trends. We also evaluated if there are pure geographical trends not accounted for by the environmental or spatial factors. The environmental variables and spatial filters that simultaneously correlated with the geographical variables and SR were considered potential causes of the geographic trends. We performed partial correlations between SR and the geographical variables, maintaining the selected explanatory variables statistically constant, to determine if SR was fully explained by them or if a significant residual geographic pattern remained. All groups and subgroups presented a latitudinal gradient not attributable to the spatial form of the country. Most of these trends were not explained by climate.We used a variation partitioning procedure to quantify the pure geographic trend (PGT) that remained unaccounted for. The PGT was larger for latitudinal than for longitudinal gradients. This suggests that historical or purely geographical causes may also be relevant drivers of these geographical gradients in mammal diversity

Existence and approximation of fixed points of right Bregman nonexpansive operators

We study the existence and approximation of fixed points of right Bregman nonexpansive operators in reflexive Banach space. We present, in particular, necessary and sufficient conditions for the existence of fixed points and an implicit scheme for approximating them

In vitro assessment of antagonistic activities of isolates from gilthead seabream (Sparus aurata) gastrointestinal tract fed microalgae supplemented diet

The use of probiotics has emerged as a sustainable alternative to antibiotics in the control of infectious diseases, favouring fish health management, growth performance and feed utilisation, among others. microalgae represent an interesting source of nutrients and functional ingredients for aquafeeds. However, their digestibility is often limited by the presence of anti-nutritional factors or absence of appropriate enzymatic activities in the fish gastrointestinal tract (GIT). The aims of the present work were to isolate potential probiotics from the GIT of Sparus aurata fed with a diet containing 25 % microalgae and characterize their antagonism against fish pathogens. Altogether, 117 strains were isolated from juvenile seabream (146.8 ± 16.4 g) and screened for hydrolytic enzyme activities. Results showed that 48 %, 41 %, 77 % and 30 % of isolates were able to hydrolyse protein, lipids, collagen and starch, respectively. Moreover, 46 %, 8 % and 57 % of isolates exhibited the ability to degrade phytate, tannins and cellulose, respectively. Based on these results, a total of 32 isolates were selected for inhibitory activity against several fish pathogens assessment. Inhibition against Aeromonas hydrophila and Vibrio anguillarum was detected in 38 % of the isolates, whilst 44 % and 47 % inhibited P damselae subsp. damselae and P. damselae subsp. piscicida, respectively. Inhibition abilities were detected in the isolates when tested against Tenacibaculum species. Thus, 56 % inhibited Tenacibaculum maritimum; 63 % T. soleae and 22 % T. gallaecium. Overall, results showed that three strains display ability to hydrolyse 4 of the assayed substrates and produce inhibition against 8 fish pathogens, and two strains are capable to hydrolyse 5 substrates and inhibit 8 fish pathogens. Selected strains show characteristics to be considered for further characterization as potential probiotics in gilthead seabream aquaculture and microalgae-supplemented aquafeeds.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Medication Non-Adherence in Rheumatology, Oncology and Cardiology: A Review of the Literature of Risk Factors and Potential Interventions

Medication adherence is directly associated with health outcomes. Adherence has been reviewed extensively; however, most studies provide a narrow scope of the problem, covering a specific disease or treatment. This project’s objective was to identify risk factors for non-adherence in the fields of rheumatology, oncology, and cardiology as well as potential interventions to improve adherence and their association with the risk factors. The project was developed in three phases and carried out by a Steering Committee made up of experts from the fields of rheumatology, oncology, cardiology, general medicine, and hospital and community pharmacy. In phase 1, a bibliographic review was performed, and the articles/reviews were classified according to the authors’ level of confidence in the results and their clinical relevance. In phase 2, 20 risk factors for non-adherence were identified from these articles/reviews and agreed upon in Steering Committee meetings. In phase 3, potential interventions for improving adherence were also identified and agreed upon. The results obtained show that adherence is a dynamic concept that can change throughout the course of the disease, the treatments, and other factors. Educational interventions are the most studied ones and have the highest level of confidence in the authors’ opinion. Information and education are essential to improve adherence in all patients