Restructuring of the sponge microbiome favors tolerance to ocean acidification.

Ocean acidification is increasing and affects many marine organisms. However, certain sponge species can withstand low-pH conditions. This may be related to their complex association with microbes. We hypothesized that species with greater microbial diversity may develop functional redundancy that could enable the holobiont to survive even if particular microbes are lost at low-pH conditions. We evaluated the effects of acidification on the growth and associated microbes of three ubiquitous Mediterranean sponges by exposing them to the present pH level and that predicted for the year 2100. We found marked differences among the species in the acquisition of new microbes, being high in Dysidea avara, moderate in Agelas oroides and null in Chondrosia reniformis; however, we did not observe variation in the overall microbiome abundance, richness or diversity. The relative abilities to alter the microbiomes contributes to survivorship in an OA scenario as demonstrated by lowered pH severely affecting the growth of C. reniformis, halving that of A. oroides, and unaffecting D. avara. Our results indicate that functional stability of the sponge holobiont to withstand future OA is species-specific and is linked to the species' ability to use horizontal transmission to modify the associated microbiome to adapt to environmental change.

Detrimental effects of ocean acidification on the economically important Mediterranean red coral (Corallium rubrum).

The mean predicted decrease of 0.3-0.4 pH units in the global surface ocean by the end of the century has prompted urgent research to assess the potential effects of ocean acidification on the marine environment, with strong emphasis on calcifying organisms. Among them, the Mediterranean red coral (Corallium rubrum) is expected to be particularly susceptible to acidification effects, due to the elevated solubility of its Mg-calcite skeleton. This, together with the large overexploitation of this species, depicts a bleak future for this organism over the next decades. In this study, we evaluated the effects of low pH on the species from aquaria experiments. Several colonies of C. rubrum were long-term maintained for 314 days in aquaria at two different pH levels (8.10 and 7.81, pHT ). Calcification rate, spicule morphology, major biochemical constituents (protein, carbohydrates and lipids) and fatty acids composition were measured periodically. Exposure to lower pH conditions caused a significant decrease in the skeletal growth rate in comparison with the control treatment. Similarly, the spicule morphology clearly differed between both treatments at the end of the experiment, with aberrant shapes being observed only under the acidified conditions. On the other hand, while total organic matter was significantly higher under low pH conditions, no significant differences were detected between treatments regarding total carbohydrate, lipid, protein and fatty acid composition. However, the lower variability found among samples maintained in acidified conditions relative to controls, suggests a possible effect of pH decrease on the metabolism of the colonies. Our results show, for the first time, evidence of detrimental ocean acidification effects on this valuable and endangered coral species.

Sensitivity effects in Uk'37 paleotemperature estimation by chemical ionization mass spectrometry.

Analysis of C37 alkenone mixtures by gas chromatography (GC) with flame ionization detection (FID) and GC coupled to mass spectrometry (GC/MS) in the chemical ionization mode (CI) shows that the later is useful for paleotemperature estimation when ammonia is used as reagent gas. Conversely, the use of isobutane gives rise to Uk'37 readings that are dependent on the amount of C37 alkenones introduced in the system, being unreliable for paleoclimatic studies. However, ammonia CI GC/MS may produce Uk'37 measurements that deviate from those obtained by GC-FID, the method calibrated for temperature estimation from algal cultures and marine sedimentary data. The differences result from changes in relative sensitivity between the di- and triunsaturated alkenones and depend on the instrument used and operational conditions. This problem is solved in the present study by determination of the response factor linear equations for each alkenone and their average relative sensitivity (R) using mixtures of known composition. These parameters allow the transformation of the GC/MS readings into the GC-FID equivalents using the following equation: UG = R x UM/(1 - UM(1 - R)). Examples of the suitability of this approach are given.

Clinical and non-invasive evaluation of 12% ammonium lactate emulsion for the treatment of dry skin in atopic and non-atopic subjects.

Clinical dryness of the leg skin is a common problem among dermatological patients. The efficacy and safety of 12% ammonium lactate emulsion (Keratisdin) for the treatment of dry skin on the legs of atopic and non-atopic subjects has been assessed by clinical criteria and by five different non-invasive methods. These methods measure biophysical parameters such as electrical capacitance of stratum corneum, skin surface lipids, transepidermal water loss (TEWL), skin surface topography (scanning electron microscopy and image analysis) as well as the biomechanical properties of the skin. Treatment with the test emulsion significantly reduced the severity scores for dryness, desquamation and pruritus when measured 15 days later. All patients tested showed a significant increase in electrical capacitance, skin surface lipids, extensibility and firmness of the skin, and an improvement in the skin barrier function and skin surface topography. This study showed that non-invasive techniques are excellent complementary tools in clinical studies.

The inhibitory effect of some amphoteric surfactants on the irritation potential of alkylsulphates.

Synopsis The physico-chemical and biological properties of an amphoteric/anionic system and its behaviour against a proteinic support have been thoroughly investigated. A considerable inhibition of adsorption of SLS (sodium lauryl sulphate) on human callus caused by the presence of definite amounts of AABet (alkyl-amido-betaines) in the treatment bath is observed. These physico-chemical results are in agreement with those obtained by some in vivo biological tests. A mechanism of the process via the formation of mixed micelles is postulated emphasizing the stability of such systems as a function of pH, the influence of the chain length of the amphoteric surfactant and the molar relative ratio SLS/AABet. Consequently, our work offers the possibility of a wide applicability of the synergic mixtures of both types of surfactants to inhibit considerably skin irritation of cosmetic finished products.

Human irritant response to different qualities and concentrations of cocoamidopropylbetaines: a possible model of paradoxical irritant response.

Cocoamidopropylbetaines are surfactants frequently used in cosmetics. We have evaluated the irritant capacity of 3 different qualities of cocoamidopropylbetaine, using the following method: patch tests have been carried out with 5 different dilutions in 67 patients and the results read at 2 days by noninvasive methods (direct visualization, transepidermal water loss (TEWL), laser Doppler flowmetry (LDF)). The results with the 3 methods were concordant. However, the results with the different concentrations were paradoxical, as irritancy did not increase at higher concentrations. We have tried to explain this by the fact that these substances contain by-products (free amidoamine and sodium monochloroacetate), the concentrations tested all being above the critical micelle concentration and therefore containing both micelles and monomer. Finally, we believe that noninvasive methods such as TEWL and LDF could be of great use in the evaluation of irritant contact dermatitis.

Applications of ternary systems in specific cosmetic formulations.

Synopsis The study of ternary systems leads to the understanding of the physico-chemical aspect and allows the contribution of the different components to a cosmetic formulation to be developed. The present investigation was centred in the zone of transparent get belonging to a previously studied ternary system containing a broad variety of different structural compositions. The possibility of including an active sunscreen as well as the ability to increase the water content of the gel was studied. The microscopical study of the compositions with polarized light allowed us to assign the corresponding different structures. A correlation between these structures and their physico-chemical properties, with special emphasis to rheology, has been established.

Use of microemulsions as vehicles for nucleophilic reagents in cosmetic formulations.

Synopsis The modifications of chemical reactivity induced in the human hair during its treatment with oxidative (H(2)O(2)) or reductive (HSO(3)Na) agents via a micellar or a microemulsion system have been investigated. For this purpose, phase diagrams of micellar solutions and microcmulsions with H(2)O(2) or NaSO(3)H have been made in order to find out the corresponding areas of solubility. The properties of conductivity, surface tension and light scattering of various monophasic compositions as a function of their water content, have been studied. As a result of the chemical reactivity data of human hair obtained through the reaction of H(2)O(2) or HSO(3)Na via a micellar or a microemulsion system, it appears reasonable to predict a more effective reaction of such agents with cystine residues existing in keratinic substrates, particularly when they are applied via a microemulsion. The decrease of the water content of the compositions considered, increases chemical reactivity of the keratinic proteins favouring the formation of cysteine and of cysteic acid in the reductive or oxidative treatments respectively.

Physico-chemical modifications of liposome structures through interaction with surfactantsy.

Synopsis The liposome-surfactant interaction has been studied in this paper through the disrupting effect caused by surfactant molecules on large unilamellar vesicles prepared by reverse-phase evaporation. This process leads, in the end, to the rupture of such structures and to the solubilization of the phospholipidic components, via mixed surfactant-phospholipid micelle formation. This phenomenon is described by a three-stage model and characterized by two parameters: the highest surfactant/phospholipid ratio that can exist in a vesicle (R(e sat)) and the lowest surfactant/phospholipid ratio required to keep the lipid and surfactant in the form of mixed micelles (R(e sat)). These parameters have been determined by spectrophotometry and (31)P NMR spectroscopy, obtaining results in a good agreement with both techniques. The surfactants tested have been: sodium dodecyl sulfate (SDS), sodium laurylether sulfate (SLES), N-hexadecyl-trimethylammonium bromide (HTAB), octylphenol series (8-20 EO) and alkylbetaines(C-10, C-12 and C-14). Different R(e sat) and R(e sol) values have been obtained for each of the surfactants. This has permitted a study of the solubilizing capacity versus the phospholipidic bilayer of the different surfactants as a function of their structure.