Interactive Effects of Ceftriaxone and Chitosan Immobilization on the Production of Arachidonic Acid by and the Microbiome of the Chlorophyte Lobosphaera sp. IPPAS C-2047

Pharmaceuticals including antibiotics are among the hazardous micropollutants (HMP) of the environment. Incomplete degradation of the HMP leads to their persistence in water bodies causing a plethora of deleterious effects. Conventional wastewater treatment cannot remove HMP completely and a promising alternative comprises biotechnologies based on microalgae. The use of immobilized microalgae in environmental biotechnology is advantageous since immobilized cultures allow the recycling of the microalgal cells, support higher cell densities, and boost tolerance of microalgae to stresses including HMP. Here, we report on a comparative study of HMP (exemplified by the antibiotic ceftriaxone, CTA) removal by suspended and chitosan-immobilized cells of Lobosphaera sp. IPPAS C-2047 in flasks and in a column bioreactor. The removal of CTA added in the concentration of 20 mg/L was as high as 65% (in the flasks) or 85% (in the bioreactor). The adsorption on the carrier and abiotic oxidation were the main processes contributing 65-70% to the total CTA removal, while both suspended and immobilized cells took up 25-30% of CTA. Neither the immobilization nor CTA affected the accumulation of arachidonic acid (ARA) by Lobosphaera sp. during bioreactor tests but the subsequent nitrogen deprivation increased ARA accumulation 2.5 and 1.7 times in the suspended and chitosan-immobilized microalgae, respectively. The study of the Lobosphaera sp. microbiome revealed that the immobilization of chitosan rather than the CTA exposure was the main factor displacing the taxonomic composition of the microbiome. The possibility and limitations of the use of chitosan-immobilized Lobosphaera sp. IPPAS C-2047 for HMP removal coupled with the production of valuable long-chain polyunsaturated fatty acids is discussed.

Failure of Micractinium simplicissimum Phosphate Resilience upon Abrupt Re-Feeding of Its Phosphorus-Starved Cultures

Microalgae are naturally adapted to the fluctuating availability of phosphorus (P) to opportunistically uptake large amounts of inorganic phosphate (P_i) and safely store it in the cell as polyphosphate. Hence, many microalgal species are remarkably resilient to high concentrations of external P_i. Here, we report on an exception from this pattern comprised by a failure of the high P_i-resilience in strain Micractinium simplicissimum IPPAS C-2056 normally coping with very high P_i concentrations. This phenomenon occurred after the abrupt re-supplementation of P_i to the M. simplicissimum culture pre-starved of P. This was the case even if P_i was re-supplemented in a concentration far below the level toxic to the P-sufficient culture. We hypothesize that this effect can be mediated by a rapid formation of the potentially toxic short-chain polyphosphate following the mass influx of P_i into the P-starved cell. A possible reason for this is that the preceding P starvation impairs the capacity of the cell to convert the newly absorbed P_i into a "safe" storage form of long-chain polyphosphate. We believe that the findings of this study can help to avoid sudden culture crashes, and they are also of potential significance for the development of algae-based technologies for the efficient bioremoval of P from P-rich waste streams.

Sunscreen Effect Exerted by Secondary Carotenoids and Mycosporine-like Amino Acids in the Aeroterrestrial Chlorophyte Coelastrella rubescens under High Light and UV-A Irradiation

The microalga Coelastrella rubescens dwells in habitats with excessive solar irradiation; consequently, it must accumulate diverse compounds to protect itself. We characterized the array of photoprotective compounds in C. rubescens. Toward this goal, we exposed the cells to high fluxes of visible light and UV-A and analyzed the ability of hydrophilic and hydrophobic extracts from the cells to absorb radiation. Potential light-screening compounds were profiled by thin layer chromatography and UPLC-MS. Coelastrella accumulated diverse carotenoids that absorbed visible light in the blue-green part of the spectrum and mycosporine-like amino acids (MAA) that absorbed the UV-A. It is the first report on the occurrence of MAA in Coelastrella. Two new MAA, named coelastrin A and coelastrin B, were identified. Transmission electron microscopy revealed the development of hydrophobic subcompartments under the high light and UV-A exposition. We also evaluate and discuss sporopollenin-like compounds in the cell wall and autophagy-like processes as the possible reason for the decrease in sunlight absorption by cells, in addition to inducible sunscreen accumulation. The results suggested that C. rubescens NAMSU R1 accumulates a broad range of valuable photoprotective compounds in response to UV-A and visible light irradiation, which indicates this strain as a potential producer for biotechnology.

All common bipedal gaits emerge from a single passive model

In this paper, we systematically investigate passive gaits that emerge from the natural mechanical dynamics of a bipedal system. We use an energetically conservative model of a simple spring-leg biped that exhibits well-defined swing leg dynamics. Through a targeted continuation of periodic motions of this model, we systematically identify different gaits that emerge from simple bouncing in place. We show that these gaits arise along one-dimensional manifolds that bifurcate into different branches with distinctly different motions. The branching is associated with repeated breaks in symmetry of the motion. Among others, the resulting passive dynamic gaits include walking, running, hopping, skipping and galloping. Our work establishes that the most common bipedal gaits can be obtained as different oscillatory motions (or nonlinear modes) of a single mechanical system with a single set of parameter values. For each of these gaits, the timing of swing leg motion and vertical motion is matched. This work thus supports the notion that different gaits are primarily a manifestation of the underlying natural mechanical dynamics of a legged system. Our results might explain the prevalence of certain gaits in nature, and may provide a blueprint for the design and control of energetically economical legged robots.

Pregnancy-associated ectopic decidua

Extrauterine formation of decidua of stromal cells has been well described, particularly in the cervix and ovary. Sporadic reports have documented decidua formation of peritoneal surfaces and lymph nodes as well as ovarian ectopic decidua in pregnant patients. The apparent hormonal mechanism of this phenomenon suggests a relationship to endometriosis. Between 1983 and 1986, tissue from 10 pregnant patients (acquired from nine at cesarean section and from one at appendectomy) demonstrated submesothelial decidua formation in the form of microscopic nodules and diffuse cell arrangements in an edematous stroma. Some cases showed mild chronic inflammation. An intracytoplasmic lipofusin-type pigment was observed in one case. Four cases had diffuse omental involvement: two with small amounts of free peritoneal blood and two with peritoneal adhesions. Three cases were associated with paratubal cysts: two of these occurred in the uterine and appendiceal serosa, respectively, and one case showed involvement of a retroperitoneal lymph node associated with a pheochromocytoma. No specific gross observations were noted at surgery. There was no prior or subsequent evidence of endometriosis. A review of 958 elective tubal ligations performed between 1983 and 1985 demonstrated 52 examples (5.5%) of serosal decidua formation. Ectopic stromal decidua formation in pregnancy is: (a) a physiologic phenomenon related to the possible specialized sensitivity of the superficial coelomic stroma to progesterone; and (b) diffusely distributed in the peritoneum although it is a clinicopathologic process distinct from endometriosis.

Cutaneous cholesterol emboli with infarction clinically mimicking heparin necrosis--a case report

Cutaneous necrosis secondary to anticoagulation (heparin and warfarin) and cholesterol (atheromatous) emboli can be similar clinically and histologically. A unique case is reported of cholesterol emboli clinically mimicking heparin necrosis. The patient was a 57 year old white male who underwent coronary angioplasty and was treated with intravenous heparin. Shortly after he developed large ecchymotic areas at the level of the umbilicus and distally which progressed to eschar. Renal failure ensued and he died secondary to stress ulcers. Cholesterol emboli were demonstrated in small muscular arteries of the dermis and panniculus along with a full thickness infarct. Because of the increasing popularity of angioplasty utilizing a retrograde femoral approach plus heparin anticoagulation, it is important to recognize the difficulty in making a clinical diagnosis when cutaneous necrosis supervenes. An incisional biopsy of the skin is recommended.