Impact of incubation conditions on protein and C-Phycocyanin recovery from Arthrospira platensis post- pulsed electric field treatment

Pulsed electric field (PEF) was conducted for the extraction of proteins/C-Phycocyanins from Arthrospira platensis. The cyanobacterial suspension was treated with 1 μs long pulses at an electric field strength of 40 kV·cm−1 and a treatment energy of 114 kJ·kgsus−1 and 56 kJ·kgsus−1. For benchmarking, additional biomass was processed by high pressure homogenization. Homogeneity of the suspension prior to PEF-treatment influenced the protein/C-phycocyanin extraction efficiency. Stability of C-Phycocyanin during post-PEF incubation time was affected by incubation temperature and pH of the external medium. Biomass concentration severely affect proteins/C-Phycocyanins extraction yield via PEF-treatment. The optimum conditions for extraction of proteins/ C-Phycocyanin was obtained at 23 °C while incubating in pH 8-buffer. The energy demand for PEF-Treatment amounts to 0.56 MJ·kgdw−1 when processing biomass at 100 gdw·kgsus−1. PEF treatment enhances the protein/CPhycocyanin extraction yield, thus, it can be suggested as preferential downstream processing method for the production of C-Phycocyanin from A. platensis biomass

Impact of incubation conditions on protein and C-Phycocyanin recovery from Arthrospira platensis post- pulsed electric field treatment

Pulsed electric field (PEF) was conducted for the extraction of proteins/C-Phycocyanins from Arthrospira platensis. The cyanobacterial suspension was treated with 1 μs long pulses at an electric field strength of 40 kV·cm−1 and a treatment energy of 114 kJ·kgsus−1 and 56 kJ·kgsus−1. For benchmarking, additional biomass was processed by high pressure homogenization. Homogeneity of the suspension prior to PEF-treatment influenced the protein/C-phycocyanin extraction efficiency. Stability of C-Phycocyanin during post-PEF incubation time was affected by incubation temperature and pH of the external medium. Biomass concentration severely affect proteins/C-Phycocyanins extraction yield via PEF-treatment. The optimum conditions for extraction of proteins/ C-Phycocyanin was obtained at 23 °C while incubating in pH 8-buffer. The energy demand for PEF-Treatment amounts to 0.56 MJ·kgdw−1 when processing biomass at 100 gdw·kgsus−1. PEF treatment enhances the protein/CPhycocyanin extraction yield, thus, it can be suggested as preferential downstream processing method for the production of C-Phycocyanin from A. platensis biomass

Biological signalling supports biotechnology – Pulsed electric fields extract a cell-death inducing factor from Chlorella vulgaris

Compared to mechanical extraction methods, pulsed electric field (PEF) treatment provides an energy-efficient and gentle alternative. However, the biological processes involved are poorly understood. The unicellular green microalga Chlorella vulgaris was used as model organism to investigate the effect of PEF treatment on biological cells. A viability assay using fluorescein diacetate measured by flow cytometry was established. The influence of developmental stage on viability could be shown in synchronised cultures when applying PEF treatment with very low specific energies where one part of cells undergoes cell death, and the other part stays viable after treatment. Reactive oxygen species generation after similar low-energy PEF treatment could be shown, indicating that PEFs could act as abiotic stress signal. Most importantly, a cell-death inducing factor could be extracted. A water-soluble extract derived from microalgae suspensions incubated for 24 h after PEF treatment caused the recipient microalgae to die, even though the recipient cells had not been subjected to PEF treatment directly. The working model assumes that low-energy PEF treatment induces programmed cell death in C. vulgaris while specifically releasing a cell-death inducing factor. Low-energy PEF treatment with subsequent incubation period could be a novel biotechnological strategy to extract soluble proteins and lipids in cascade process

Protein recovery assisted by pulsed electric field treatment from microalgae Chlorella vulgaris and Artrospira platensis

One of the major global challenges of the 21st century is the sustainable supply of the growing world population with food, raw materials and energy. Microalgae cultivated outside farmland under photoautotrophic conditions are a suitable source of renewable raw biomass. By adequate processing of microalgae biomass, products with unique properties can be used as food and feed supplements, in cosmetics and agriculture. The best known examples are dyes astaxanthin, phycocyanin and ß-carotene as well as polyunsaturated fatty acids (PUFA). In spite of this appeal the worldwide production of dry microalgae biomass is only few thousand tonnes per year. This is due to the high investment costs in photo-bioreactors (PBR) and the high energy consumption during down-stream processing of microalgae biomass. To reduce these costs, new technologies and processing methods are required. A suitable alternative to mechanical disruption approaches is the pulsed electric field (PEF) treatment. The extraction efficiency is lower compared to mechanical disruption methods, but the biomass separability is maintained since the morphology of the cells barely changes. In this study we evaluated the potential of PEF treatment for protein and phycocyanin recovery from Chlorella vulgaris and Arthrospira platensis respectively. It is assumed that irreversible electroporation of the cell membrane and the subsequent increased permeabilization are the main effects which allows proteins and other ingredients to pass through the membrane. We observed in our study that efficient protein extraction after PEF treatment requires an incubation step and the progress and kinetics of this outflow is dependent on the biomass concentration and the incubation temperature. The impairment of the molecular outflow at higher temperature (50 °C) and at higher biomass concentration are hints for two different effects. Beside diffusion in a chemical gradient a second biological, enzyme-regulated process within the PEF-treated biomass that facilitates release of proteins from the cells, was considered. This presentation will give an overview about the various factors, such as the post PEF treatment incubation parameters, which have an impact on protein release, as it could be possible to optimize the incubation in order to obtain higher yields

Targeting surface nucleolin with a multivalent pseudopeptide delays development of spontaneous melanoma in RET transgenic mice

<p>Abstract</p> <p>Background</p> <p>The importance of cell-surface nucleolin in cancer biology was recently highlighted by studies showing that ligands of nucleolin play critical role in tumorigenesis and angiogenesis. By using a specific antagonist that binds the C-terminal tail of nucleolin, the HB-19 pseudopeptide, we recently reported that HB-19 treatment markedly suppressed the progression of established human breast tumor cell xenografts in the athymic nude mice without apparent toxicity.</p> <p>Methods</p> <p>The <it>in vivo </it>antitumoral action of HB-19 treatment was assessed on the spontaneous development of melanoma in the RET transgenic mouse model. Ten days old RET mice were treated with HB-19 in a prophylactic setting that extended 300 days. In parallel, the molecular basis for the action of HB-19 was investigated on a melanoma cell line (called TIII) derived from a cutaneous nodule of a RET mouse.</p> <p>Results</p> <p>HB-19 treatment of RET mice caused a significant delay in the onset of cutaneous tumors, several-months delay in the incidence of large tumors, a lower frequency of cutaneous nodules, and a reduction of visceral metastatic nodules while displaying no toxicity to normal tissue. Moreover, microvessel density was significantly reduced in tumors recovered from HB-19 treated mice compared to corresponding controls. Studies on the melanoma-derived tumor cells demonstrated that HB-19 treatment of TIII cells could restore contact inhibition, impair anchorage-independent growth, and reduce their tumorigenic potential in mice. Moreover, HB-19 treatment caused selective down regulation of transcripts coding matrix metalloproteinase 2 and 9, and tumor necrosis factor-α in the TIII cells and in melanoma tumors of RET mice.</p> <p>Conclusions</p> <p>Although HB-19 treatment failed to prevent the development of spontaneous melanoma in the RET mice, it delayed for several months the onset and frequency of cutaneous tumors, and exerted a significant inhibitory effect on visceral metastasis. Consequently, HB-19 could provide a novel therapeutic agent by itself or as an adjuvant therapy in association with current therapeutic interventions on a virulent cancer like melanoma.</p

Distinct Roles of Estrogen Receptor-α and β in the Modulation of Vascular Inducible Nitric-Oxide Synthase in Diabetes

Estrogen is known to affect vascular function and diabetes development, but the relative contribution of estrogen receptor (ER) isoforms is unclear. The aim of this study was to determine how individual ER isoforms modulate inflammatory enzymes in the vascular wall of control and streptozotocin (STZ)-injected rodents. Primary cultures of rat aortic smooth muscle cells (SMCs) were stimulated with inflammatory agents in the presence or absence of increasing concentrations of the ERα and ERβ-selective agonists 4,4′,4′′-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol (PPT) and diarylpropionitrile (DPN), respectively. The production of inducible nitric-oxide synthase (iNOS), a classical indicator of vascular inflammation, was significantly reduced by PPT in control but not diabetic SMCs, whereas it was further enhanced by DPN treatment in both groups. This distinct action profile was not related to changes in ER transcriptional activity. However, extracellular signal-regulated kinase 1/2 signaling was activated by DPN but not by PPT in cytokine-treated SMCs. In cultured aortic rings from both normoglycemic and STZ-diabetic mice, pharmacological activation of ERα attenuated cytokine-driven iNOS induction by 30 to 50%. Vascular iNOS levels were decreased consistently when adding 1 nM 17β-estradiol to aortic tissues from ERβ- but not ERα-knockout mice. These findings suggest a possible role for ERα-selective ligands in reducing vascular inflammatory responses under normo- and hyperglycemic conditions