Diet of the invasive sea slug Pleurobranchaea maculata in Patagonian coastal waters

High densities of the invasive sea slug, Pleurobranchaea maculata, have been detected on the Argentinean coast, but studies on the species’ adaptation have been absent until now. Stomach contents of P. maculata in two sampling sites located at Golfo Nuevo, Patagonia Argentina, revealed animals as a major prey, but surprisingly algae ingestion on both sampling sites was abundant. This fact was not reported in previous studies that described opportunistic carnivorous feeding habits of species belonging to the genus Pleurobranchaea. Significant differences in the species prey items were found between sampling sites; however, sedentary polychaetes were the main consumed group at both sites. These results are useful to understand the adaptation of this invasive species in Argentinean waters and to monitor future changes in the benthic communities colonised by P. maculata.     

From amino alcohol to aminopolyol: one-pot multienzyme oxidation and aldol addition

In this work, the successful coupling of enzymatic oxidation and aldol addition reactions for the synthesis of a Cbz-aminopolyol from a Cbz-amino alcohol was achieved for the first time in a multienzymatic one-pot system. The two-step cascade reaction consisted of the oxidation of Cbz-ethanolamine to Cbz-glycinal catalyzed by chloroperoxidase from the fungus Caldariomyces fumago and aldol addition of dihydroxyacetone phosphate to Cbz-glycinal catalyzed by rhamnulose-1-phosphate aldolase expressed as a recombinant enzyme in Escherichia coli, yielding (3R,4S)-5-{[(benzyloxy)carbonyl]amino}-5-deoxy-1-O-phosphonopent-2-ulose. Tools of enzymatic immobilization, reactor configurations, and modification of the reaction medium were applied to highly increase the production of the target compound. While the use of soluble enzymes yielded only 23.6 % of Cbz-aminopolyol due to rapid enzyme inactivation, the use of immobilized ones permitted an almost complete consumption of Cbz-ethanolamine, reaching Cbz-aminopolyol yields of 69.1 and 71.9 % in the stirred-tank and packed-bed reactor, respectively. Furthermore, the reaction production was 18-fold improved when it was catalyzed by immobilized enzymes in the presence of 5 % (v/v) dioxane, reaching a value of 86.6 mM of Cbz-aminopoliol (31 g/L).     

Two-dimensional boron nitride structures functionalization: first principles studies

Density functional theory calculations have been performed to investigate two-dimensional hexagonal boron nitride (2D hBN) structures functionalization with organic molecules. 2x2, 4x4 and 6x6 periodic 2D hBN layers have been considered to interact with acetylene. To deal with the exchange-correlation energy the generalized gradient approximation (GGA) is invoked. The electron-ion interaction is treated with the pseudopotential method. The GGA with the Perdew-Burke-Ernzerhoff (PBE) functionals together with van der Waals interactions are considered to deal with the composed systems. To investigate the functionalization two main configurations have been explored; in one case the molecule interacts with the boron atom and in the other with the nitrogen atom. Results of the adsorption energies indicate chemisorption in both cases. The total density of states (DOS) displays an energy gap in both cases. The projected DOS indicate that the B-p and N-p orbitals are those that make the most important contribution in the valence band and the H-s and C-p orbitals provide an important contribution in the conduction band to the DOS. Provided that the interactions of the acetylene with the 2D layer modify the structural and electronic properties of the hBN the possibility of structural functionalization using organic molecules may be concluded.     

A new formulated stable papin-pectin aerosol spray for skin wound healing

A new spray-on topical wound debrider composition consisting of 0.1% w/v papain immobilized in 6% w/v pectin gel was formulated for skin wound healing. The stability of the enzyme activity of this new formulated spray was compared with the 0.1% w/v papain in water solution at the refrigerated temperature of 4 and 75°C. Two aerosol propellants, air and nitrogen, were evaluated for their efficacy. The new formulated spray was then evaluated for its thermal stability under air and N₂ at 75°C. All enzyme activity of papain was measured with a spectrophotometer using casein as a substrate at 37°C and in 0.1 M phosphate buffer at pH 6, as well as trichloral acetic acid to separate the product of casein hydrolysis. All the evaluations showed the new aerosol spray formulation to be far better than the liquid formulation in storage stability and thermal stability at 75°C under atmospheric or higher pressures. The new formulation was tested in a rabbit experiment to evaluate the effectiveness of wound healing. As compared to untreated wound, the formulated spray clearly was superior, yielding a 20% more healing progress in the first 4 days alone.     

Undaria pinnatifida exudates trigger shifts in seawater chemistry and microbial communities from Atlantic Patagonian coasts

Biological Invasions - The invasive kelp Undaria pinnatifida has spread from northeastern Asia to temperate coastal environments worldwide, with profound effects on colonized ecosystems. In this...