Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

The recognition that ultraviolet radiation has harmful effects on the skin has led to the commercial development of inorganic and synthetic organic UV filters that can reduce the negative effects of exposure to sunlight. In addition, moisturizing chemicals are extensively used in personal care products to improve the ability of skin to retain water. Whilst current UV filter and moisturizing chemicals have clear beneficial qualities, they may also have adverse effects such as contact sensitivity, oestrogenicity and even tumorigenic effects on human skin. Furthermore, the accumulation of these chemicals in the aquatic environment could be potentially harmful. Consequently, there is interest in exploiting safer alternatives derived from biological sources, especially from photosynthetic organisms such as cyanobacteria which have developed mechanisms for coping with high UV irradiation and desiccation. In order to overcome the detrimental effects of UV radiation, these microorganisms produce UV screening compounds such as mycosporine-like amino acids and scytonemin, which are good candidates as alternatives to current synthetic UV filters. In addition, extracellular substances produced by some extremophilic species living in hyper-arid habitats have a high water retention capacity and could be used in cosmetic products as moisturizers. In this review, we present an overview of the literature describing the potential of cyanobacterial metabolites as an alternative source for sunscreens and moisturizers

Applications of Microalgal Biotechnology for Disease Control in Aquaculture

Aquaculture industries, and in particular the farming of fish and crustaceans, are major contributors to the economy of many countries and an increasingly important component in global food supply. However, the severe impact of aquatic microbial diseases on production performance remains a challenge to these industries. This article considers the potential applications of microalgal technology in the control of such diseases. At the simplest level, microalgae offer health-promoting benefits as a nutritional supplement in feed meal because of their digestibility and high content of proteins, lipids and essential nutrients. Furthermore, some microalgal species possess natural anti-microbial compounds or contain biomolecules that can serve as immunostimulants. In addition, emerging genetic engineering technologies in microalgae offer the possibility of producing 'functional feed additives' in which novel and specific bioactives, such as fish growth hormones, anti-bacterials, subunit vaccines, and virus-targeted interfering RNAs, are components of the algal supplement. The evaluation of such technologies for farm applications is an important step in the future development of sustainable aquaculture

Molecular structure of photosynthetic microbial biofuels for improved engine combustion and emissions characteristics.

The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as bioethanol and fatty acid methyl esters, have been developed primarily as drop-in replacements for existing fossil fuels, based on their physical properties and autoignition characteristics under specific combustion regimes. However, advances in the genetic engineering of microalgae and cyanobacteria, and the application of synthetic biology approaches offer the potential of designer strains capable of producing hydrocarbons and oxygenates with specific molecular structures. Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion. This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes

Detection and Enhancement of Ketocarotenoid Accumulation in the Newly Isolated Sarcinoid Green Microalga Chlorosarcinopsis PY02

The sarcinoid alga PY02 is a newly isolated soil alga native to western Thailand. In this study PY02 is described, the carotenoid profile of the green and red forms of the algal cells are compared, and the effect of nitrogen reduction and media volume on ketocarotenoid production are reported. Partial sequences of the genes from elongation factor Tu (tufA) and 18S rRNA reveal that the alga is from theChlorosarcinopsisgenus. Growth studies demonstrated thatChlorosarcinopsisPY02 is capable of photoautotrophic, heterotrophic and mixotrophic growth. A gradual change in colony colour from green to red was observed over a period of four weeks under mixotrophic conditions. Pigment analysis of lyophilized red cells using ultrahigh performance liquid chromatography (UPLC) with Photo Diode Array Detection (PDA), showed for the first time that an alga from the genusChlorosarcinopsisis capable of producing ketocarotenoids such as adonixanthin and 3-OH-echinenone, with canthaxanthin as the dominant pigment. Interestingly, a reduction of nitrogen in the medium exerts a positive effect on the rate of colour change from one month to less than seven days. Enhancements of the canthaxanthin content from 520 to 1504 or 1427 µg·gDW-1were detected under 50% and 10% nitrogen content, respectively. An increase of 16% in biomass production of PY02 was unexpectedly detected from a 50% nitrogen reduction under mixotrophic culture. Notably, in liquid mixotrophic media with volumes of 15, 30 and 60 mL, the lowest volume produced a significantly higher biomass and canthaxanthin content

Combustion and emissions characterization of terpenes with a view to their biological production in cyanobacteria

In developing future fuels there is an opportunity to make use of advances in many fields of science and engineering to ensure that such fuels are sustainable in both production and utilization. One such advance is the use of synthetic biology to re-engineer photosynthetic micro-organisms such that they are able to produce novel hydrocarbons directly from CO2. Terpenes are a class of hydrocarbons that can be produced biologically and have potential as liquid transport fuels. This paper presents experimental studies on a compression ignition engine and spark ignition engine in which the combustion and emissions of 12 different terpenes that could potentially be produced by cyanobacteria were assessed as single components and blends with fossil diesel and fossil gasoline. The 12 terpenes were chosen to explore how small changes to the molecular structure of geraniol (a terpene most easily produced by cyanobacteria) impact on combustion and emissions. Furthermore, the toxicity of some of the best performing terpenes were assessed using the model cyanobacterium Synechocystis sp. PCC6803 (hereafter, Synechocystis) as a prelude to a metabolic engineering programme. The compression ignition engine tests were carried out at constant injection timing and constant ignition timing, and the spark ignition engine tests were conducted at a constant spark timing and a constant lambda value of 1. Of the terpenes tested in the compression ignition engine, geranial and farnesene were found to be the best performing single component fuels in terms of combustion and emissions. In blends with fossil diesel, the presence of geranial or farnesene did not have a significant effect on combustion phasing up to a terpene content of 20% (wt/wt), though levels of NOx and CO did increase. In the spark ignition engine experiments of terpene and fossil gasoline blends, citronellene and linalool were found to be soluble in fossil gasoline and combusted in a steady manner up to a terpene content of 45% and 65% (wt/wt) respectively. Of those terpenes with the most potential as either diesel or gasoline fuels, geraniol and geranial were found to be the most toxic to Synechocystis, with farnesene and linalool less toxic and citronellene having no detrimental effect. Addition of n-dodecane to the cultures was found to ameliorate the toxic effects of all five terpenes

Antiviral CD4+ memory T cells are IL-15 dependent

Survival and intermittent proliferation of memory CD4+ and CD8+ T cells appear to be controlled by different homeostatic mechanisms. In particular, contact with interleukin (IL)-15 has a decisive influence on memory CD8+ cells, but not memory CD4+ cells. Past studies of memory CD4+ cells have relied heavily on the use of naturally occurring memory phenotype (MP) cells as a surrogate for antigen (Ag)-specific memory cells. However, we show here that MP CD4+ cells contain a prominent subset of rapidly proliferating major histocompatibility complex (MHC) II–dependent cells. In contrast, Ag-specific memory CD4 cells have a slow turnover rate and are MHC II independent. In irradiated hosts, these latter cells ignore IL-15 and expand in response to the elevated levels of IL-7 in the lymphopenic hosts. In contrast, in normal nonlymphopenic hosts where IL-7 levels are low, memory CD4 cells are heavily dependent on IL-15. Significantly, memory CD4+ responsiveness to endogenous IL-15 reflects marked competition from other cells, especially CD8+ and natural killer cells, and increases considerably after removal of these cells. Therefore, under normal physiological conditions, homeostasis of CD8+ and CD4+ memory cells is quite similar and involves IL-15 and IL-7

The spectral energy distribution of D-type symbiotic stars: the role of dust shells

We have collected continuum data of a sample of D-type symbiotic stars. By modelling their spectral energy distribution in a colliding-wind theoretical scenario we have found the common characteristics to all the systems: 1) at least two dust shells are clearly present, one at \sim 1000 K and the other at \sim 400 K; they dominate the emission in the IR; 2) the radio data are explained by thermal self-absorbed emission from the reverse shock between the stars; while 3) the data in the long wavelength tail come from the expanding shock outwards the system; 4) in some symbiotic stars, the contribution from the WD in the UV is directly seen. Finally, 5) for some objects soft X-ray emitted by bremsstrahlung downstream of the reverse-shock between the stars are predicted. The results thus confirm the validity of the colliding wind model and the important role of the shocks. The comparison of the fluxes calculated at the nebula with those observed at Earth reveals the distribution throughout the system of the different components, in particular the nebulae and the dust shells. The correlation of shell radii with the orbital period shows that larger radii are found at larger periods. Moreover, the temperatures of the dust shells regarding the sample are found at 1000 K and <=400 K, while, in the case of late giants, they spread more uniformly throughout the same range.Comment: 14 pages, 7 figures, 5 tables. Accepted for publication in MNRA

Shock fronts in the symbiotic system BI Crucis

We investigate the symbiotic star BI Crucis through a comprehensive and self-consistent analysis of the spectra emitted in three different epochs: 60's, 70's, and late 80's. In particular, we would like to find out the physical conditions in the shocked nebula and in the dust shells, as well as their location within the symbiotic system, by exploiting both photometric and spectroscopic data from radio to UV. We suggest a model which, on the basis of optical imaging, emission line ratios and spectral energy distribution profile, is able to account for collision of the winds, formation of lobes and jets by accretion onto the WD, as well as for the interaction of the blast wave from a past, unrecorded outburst with the ISM. We have found that the spectra observed throughout the years show the marks of the different processes at work within BI Cru, perhaps signatures of a post-outburst evolution. We then call for new infrared and millimeter observations, potentially able to resolve the inner structure of the symbiotic nebula.Comment: 13 pages, 9 figures, 2 tables; accepted for publication in MNRA

Comparative analysis of the relative fragmentation stabilities of polymorphic alpha-synuclein amyloid fibrils

The division of amyloid fibril particles through fragmentation is implicated in the progression of human neurodegenerative disorders such as Parkinson’s disease. Fragmentation of amyloid fibrils plays a crucial role in the propagation of the amyloid state encoded in their three-dimensional structures and may have an important role in the spreading of potentially pathological properties and phenotypes in amyloid-associated diseases. However, despite the mechanistic importance of fibril fragmentation, the relative stabilities of different types or different polymorphs of amyloid fibrils toward fragmentation remain to be quantified. We have previously developed an approach to compare the relative stabilities of different types of amyloid fibrils toward fragmentation. In this study, we show that controlled sonication, a widely used method of mechanical perturbation for amyloid seed generation, can be used as a form of mechanical perturbation for rapid comparative assessment of the relative fragmentation stabilities of different amyloid fibril structures. This approach is applied to assess the relative fragmentation stabilities of amyloid formed in vitro from wild type (WT) α-synuclein and two familial mutant variants of α-synuclein (A30P and A53T) that generate morphologically different fibril structures. Our results demonstrate that the fibril fragmentation stabilities of these different α-synuclein fibril polymorphs are all highly length dependent but distinct, with both A30P and A53T α-synuclein fibrils displaying increased resistance towards sonication-induced fibril fragmentation compared with WT α-synuclein fibrils. These conclusions show that fragmentation stabilities of different amyloid fibril polymorph structures can be diverse and suggest that the approach we report here will be useful in comparing the relative stabilities of amyloid fibril types or fibril polymorphs toward fragmentation under different biological conditions