Enhancement of Chlorella vulgaris harvesting via the electro-coagulation-flotation (ECF) method.

This article explores the potential of using an electro-coagulation-flotation (ECF) harvester to allow flotation of microalgae cells for surface harvesting. A response surface methodology (RSM) model was used to optimize ECF harvesting by adjusting electrode plate material, electrode plate number, charge of the electrodes, electrolyte concentration, and pH value of the culture solution. The result revealed that three aluminum electrode plates (one anode and two cathodes), brine solution (8 g/L), and acidity (pH = 4) of culture solution (optimized ECF harvester) The highest flocculant concentration was measured at 2966 mg/L after 60 min and showed a 79.8 % increase of flocculation concentration. Such results can provide a basis for designing a large-scale microalgae harvester for commercial use in the future.

Maximization of cell growth and lipid production of freshwater microalga Chlorella vulgaris by enrichment technique for biodiesel production.

Chlorella vulgaris was cultivated under limitation and starvation and under controlled conditions using different concentrations of nitrate (NaNO3) and phosphate (K2HPO4 and KH2PO4) chemicals in modified Bold basal medium (BBM). The biomass and lipid production responses to different media were examined in terms of optical density, cell density, dry biomass, and lipid productivity. In the 12-day batch culture period, the highest biomass productivity obtained was 72.083 mg L-1 day-1 under BBM - NcontrolPlimited condition. The highest lipid content, lipid concentration, and lipid productivity obtained were 53.202 %, 287.291 mg/L, and 23.449 mg L-1 day-1 under BBM - NControlPDeprivation condition, respectively. Nitrogen had a major effect in the biomass concentration of C. vulgaris, while no significant effect was found for phosphorus. Nitrogen and phosphorus starvation was found to be the strategy affecting the lipid accumulation and affected the lipid composition of C. vulgaris cultures.

Combined effects of land reclamation, channel dredging upon the bioavailable concentration of polycyclic aromatic hydrocarbons (PAHs) in Victoria Harbour sediment, Hong Kong.

The up-to-date concentration of polycyclic aromatic hydrocarbons (PAHs) in sediment materials of Victoria Harbour was investigated so as to evaluate the pollution potential associated with the reclamation projects in Hong Kong. A total of 100 sediment samples were collected at 20 locations. Except the control point in reservoir, the PAHs concentrations were detectable levels all sites (131-628.3ng/g, dw) and such values were higher than Dutch Target and Intervention Values (the New Dutch standard in 2016). The PAHs concentration indicating that construction waste and wastewater discharges were the main pollutant sources. Results of correlation in single cell gel electrophoresis assay (comet assay) studies also revealed that the PAHs concentration was highly correlated (<0.01) with DNA migration (i.e. the length of tail moment of fish cells) in 5mg/ml of PAHs. The above observation indicates that the PAHs present in the sediment may substantially effect the marine ecosystem. Although the dredged sediment can be a useful sea-filling material for land reclamation; however, the continuing leaching of PAHs and its impact on the aquatic environment need to be studied further.

Monitoring and assessment of heavy metal contamination in a constructed wetland in Shaoguan (Guangdong Province, China): bioaccumulation of Pb, Zn, Cu and Cd in aquatic and terrestrial components.

The objective of this study is to evaluate the current status of heavy metal concentrations in constructed wetland, Shaoguan (Guangdong, China). Sediments, three wetland plants (Typha latifolia, Phragmites australis, and Cyperus malaccensis), and six freshwater fish species [Carassius auratus (Goldfish), Cirrhinus molitorella (Mud carp), Ctenopharyngodon idellus (Grass carp), Cyprinus carpio (Wild common carp), Nicholsicypris normalis (Mandarin fish), Sarcocheilichthys kiangsiensis (Minnows)] in a constructed wetland in Shaoguan were collected and analyzed for their heavy metal compositions. Levels of Pb, Zn, Cu, and Cd in sediments exceeded approximately 532, 285, 11, and 66 times of the Dutch Intervention value. From the current study, the concentrations of Pb and Zn in three plants were generally high, especially in root tissues. For fish, concentrations of all studied metals in whole body of N. mormalis were the highest among all the fishes investigated (Pb 113.4 mg/kg, dw; Zn 183.1 mg/kg, dw; Cu 19.41 mg/kg, dw; 0.846 mg/kg, dw). Heavy metal accumulation in different ecological compartments was analyzed by principle component analysis (PCA), and there is one majority of grouped heavy metals concentration as similar in composition of ecological compartment, with the Cd concentration quite dissimilar. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation by constructed wetland is still in early stage and needs more attention in gene manipulation area.

Cultivation of Chlorella vulgaris in Column Photobioreactor for Biomass Production and Lipid Accumulation.

Microalgae have been used as energy resources in recent decades to mitigate the global energy crisis. As the demand for pure microalgae strains for commercial use increases, designing an effective photobioreactor (PBR) for mass cultivation is important. Chlorella vulgaris, a local freshwater microalga, was used to study the algal biomass cultivation and lipid production using various PBR configurations (bubbling, air-lift, porous air-lift). The results show that a bubbling column design is a better choice for the cultivation of Chlorella vulgaris than an air-lift one. The highest biomass concentration in the bubbling PBR was 0.78 g/L while the air-lift PBR had a value of 0.09 g/L. Key operating parameters, including draft-tube length and bubbling flowrate, were then optimized based on biomass production and lipid yield. The highest lipid content was in the porous air-lift PBR and the air-lift PBR with shorter draft tube (35 cm) was also better than a longer one (50 cm) for algal cultivation, but the microalgae attachment on the inner tube of PBR always occurred. The highest biomass concentration could be produced under the highest gas flowrate of 2.7 L/min, whereas the lowest dry cell mass was under the lowest gas flowrate of 0.2 L/min.

Scenedesmus quadricauda for Nutrient Removal and Lipid Production in Wastewater.

Scenedesmus quadricauda, a local freshwater microalga, was used to treat primary settled and filtrate wastewater and to produce algal lipid. For the primary settled wastewater, the maximum biomass concentrations of acclimated and unacclimated microalgae were 0.995 g/L and 0.940 g/L, respectively. Over 90% orthophosphate and 95% ammonia nitrogen in the acclimated and unacclimated cultures, respectively, were removed after five days. The lipid contents of the microalgae were higher than 13% in all cultures. The highest growth rate occurred in the 25% filtrate culture. Over 80% phosphate was removed under the 25% and 50% filtrate cultures within six days, while over 90% ammonia nitrogen was removed within five days under both conditions. The lipid content was the highest (18.1%) under the 50% filtrate condition. C16:0, C18:2n6, and C18:3n3 were dominant fatty acids. In conclusion, S. quadricauda is a viable candidate for wastewater treatment and lipid production.

Comparative assessment of water quality parameters of mariculture for fish production in Hong Kong Waters.

The objective of the study is to evaluate the effect of fish cultivation on water quality in fish culture zone (FCZ) and analysed by Principle Component Analysis (PCA). 120 surface water samples were collected from Hong Kong Waters (60 samples in Victoria Harbour and another 60 in Ma Wan FCZ). Significant difference was found in dissolved oxygen (MW: 59.6%; VH: 81.3%), and Escherichia coli (MW: 465 CFU/100 ml; VH: 162.5 CFU/100 ml). Three principle components are responsible for water quality variations in the studying sites. The first component included E. coli (0.625) and dissolved oxygen (0.701). The second included E. coli (0.387) and ammonical-nitrogen (0.571). The third included E. coli (0.194) and ammonical-nitrogen (0.287). This framework provides information to assess the relative contribution of eco-aquaculture to nutrient loads and the subsequent risk of eutrophication. To conclude, a rigorous monitoring of water quality is necessary to assess point and nonpoint source pollution. Besides, appropriate remediation techniques should be used to combat water pollution and achieve sustainability.

Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China.

The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication.

Neural stem cells harvested from live brains by antibody-conjugated magnetic nanoparticles.

It stems from the magnetism: The extraction of stem/progenitor cells from the brain of live animals is possible using antibodies conjugated to magnetic nanoparticles (Ab-MNPs). The Ab-MNPs are introduced to a rat's brain with a superfine micro-syringe. The stem cells attach to the Ab-MNPs and are magnetically isolated and removed. They can develop into neurospheres and differentiate into different types of cells outside the subject body. The rat remains alive and healthy.

Mixed arbuscular mycorrhizal (AM) fungal application to improve growth and arsenic accumulation of Pteris vittata (As hyperaccumulator) grown in As-contaminated soil.

A greenhouse pot experiment was conducted to study the effects of three types of single inoculum [indigenous mycorrhizas (IM) isolated from As mine, Glomus mosseae (GM) and Glomus intraradices (GI)] and two types of mixed inoculum (mixed with IM and either GM or GI) on the growth response of Pteris vittata (hyperaccumulator) and Cynodon dactylon (non-hyperaccumulator) at three levels of As concentrations (0, 100 and 200mgkg(-1)). Both mycorrhizal plants exhibited significantly higher biomass, and N and P accumulation in its tissue than the control. Among the mycorrhizal inoculum, the mixed inoculum IM/GM promoted substantially higher mycorrhizal colonization and arsenate reductase activity in P. vittata than C. dactylon, among all As levels. The portion of Paris arbuscular mycorrhizal structure (observed in colonized roots) together with the highest As translocation factor of 10.2 in P. vittata inoculated with IM/GM was also noted. It was deduced that IM/GM inoculum may be the best choice for field inoculation at any contaminated lands as the inoculum exhibited better adaptation to variable environmental conditions and hence benefited the host plants.

Ceftriaxone ameliorates motor deficits and protects dopaminergic neurons in 6-hydroxydopamine-lesioned rats.

Parkinson's disease is caused by the degeneration of dopaminergic neurons in substantia nigra. There is no current promising treatment for neuroprotection of dopaminergic neurons. Ceftriaxone is a beta-lactam antibiotic and has been reported to offer neuroprotective effects (Rothstein, J.-D., Patel, S., Regan, M.-R., Haenggeli, C., Huang, Y.-H., Bergles, D.-E., Jin, L., Dykes, H.-M., Vidensky, S., Chung, D.-S., Toan, S.-V., Bruijn, L.-I., Su, Z.-Z., Gupta, P., and Fisher, P.-B. (2005) Beta-lactam antibiotics offer neuroprotection by increasing glutamate transporter expression Nature433, 73-77). In the present study, efficacy of ceftriaxone in neuroprotection of dopaminergic neurons and amelioration of motor deficits in a rat model of Parkinson's disease were investigated. Ceftriaxone was administrated in 6-hydroxydopamine-lesioned rats. Using behavioral tests, grip strength and numbers of apomorphine-induced contralateral rotation were declined in the ceftriaxone-treated group. More importantly, cell death of dopaminergic neurons was found to decrease. In addition, both the protein expression and immunoreactivity for GLT-1 were up-regulated. The present results strongly indicate that ceftriaxone is a potential agent in the treatment of Parkinson's disease.

Potential application of induced pluripotent stem cells in cell replacement therapy for Parkinson's disease.

Parkinson's disease (PD), a common degenerative disease in humans, is known to result from loss of dopamine neurons in the substantia nigra and is characterized by severe motor symptoms of tremor, rigidity, bradykinsia and postural instability. Although levodopa administration, surgical neural lesion, and deep brain stimulation have been shown to be effective in improving parkinsonian symptoms, cell replacement therapy such as transplantation of dopamine neurons or neural stem cells has shed new light on an alternative treatment strategy for PD. While the difficulty in securing donor dopamine neurons and the immuno-rejection of neural transplants largely hinder application of neural transplants in clinical treatment, induced pluripotent stem cells (iPS cells) derived from somatic cells may represent a powerful tool for studying the pathogenesis of PD and provide a source for replacement therapies in this neurodegenerative disease. Yamanaka et al. [2006, 2007] first succeeded in generating iPS cells by reprogramming fibroblasts with four transcription factors, Oct4, Sox2, Klf4, and c-Myc in both mouse and human. Animal studies have further shown that iPS cells from fibroblasts could be induced into dopamine neurons and transplantation of these cells within the central nervous system improved motor symptoms in the 6-OHDA model of PD. More interestingly, neural stem cells or fibroblasts from patients can be efficiently reprogrammed and subsequently differentiated into dopamine neurons. Derivation of patient-specific iPS cells and subsequent differentiation into dopamine neurons would provide a disease-specific in vitro model for disease pathology, drug screening and personalized stem cell therapy for PD. This review summarizes current methods and modifications in producing iPS cells from somatic cells as well as safety concerns of reprogramming procedures. Novel reprogramming strategies that deter abnormal permanent genetic and epigenetic alterations are essential for propagating clinically-qualified iPS cells. Future investigations into cell transforming and reprogramming processes are needed to generate the disease-specific iPS cells for personalized regeneration medicine of PD patients by disclosing detailed reprogramming mechanisms.

Downregulation of glial glutamate transporters after dopamine denervation in the striatum of 6-hydroxydopamine-lesioned rats.

Overactivity of glutamatergic neurotransmission in the basal ganglia is known to be closely related to the onset and pathogenesis of Parkinson's disease. Glutamate homeostasis around glutamatergic synapses is tightly regulated by two groups of glutamate transporters: glial glutamate transporters GLT1 (EAAT2) and GLAST (EAAT1), and neuronal glutamate transporter EAAC1. In order to investigate the changes of glutamate transporters after the onset of Parkinson's disease, unilateral 6-hydroxydopamine-lesioned rat, an animal model of Parkinson's disease, was employed. By immunofluorescence and Western blot analyses, GLT1 and GLAST proteins were significantly reduced in the striatum with lesion. No change in GLT1 and GLAST protein was found in the substantia nigra. The reduction of GLT1 protein in the striatum was more prominent than that of GLAST protein (approximately 40% vs. 20%). In addition, EAAC1 protein was found to be increased in the substantia nigra pars reticulata of the lesioned rats but not in the striatum. The present results indicate that reductions of GLT1 and GLAST may impair glutamate homeostasis around glutamatergic synapses in the striatum and contribute to over-spills of glutamate in the system. An increase in the EAAC1 level in the substantia nigra pars reticulata may increase GABA synthesis and enhance GABAergic neurotransmission. These results indicate that there are differential and distinct modulations of glutamate transporters after dopamine denervation in the 6-hydroxydopamine-lesioned rat.

Electroacupuncture inhibits cyclooxygenase-2 up-regulation in rat spinal cord after spinal nerve ligation.

Electroacupuncture (EA) has long been used to treat pain including neuropathic pain, but its mechanisms remain to be delineated. Since cyclooxygenase-2 (COX-2) has been reported to increase in the spinal dorsal horn following spinal nerve ligation (SNL) and it may play a role in the neuropathic pain, we hereby tested the hypothesis that EA may affect COX-2 expression and hence neuropathic nociception after SNL. The results showed that EA (2 Hz) can significantly reduce mechanical and thermal hypersensitivity following lumbar L5 SNL in rats. Immunostaining demonstrated suppression of COX-2 expression in the spinal L4-L6 dorsal horn after EA. The present results suggest that EA may alleviate neuropathic hypersensitivity by, at least partially, inhibiting COX-2 expression in the spinal cord.

5-HT excites globus pallidus neurons by multiple receptor mechanisms.

Anatomical and neurochemical studies indicated that the globus pallidus receives serotonergic innervation from raphe nuclei but the membrane effects of 5-HT on globus pallidus neurons are not entirely clear. We address this question by applying whole-cell patch-clamp recordings on globus pallidus neurons in immature rat brain slices. Under current-clamp recording, 5-HT depolarized globus pallidus neurons and increased their firing rate, an action blocked by both 5-HT(4) and 5-HT(7) receptor antagonists and attributable to an increase in cation conductance(s). Further experiments indicated that 5-HT enhanced the hyperpolarization-activated inward conductance which is blocked by 5-HT(7) receptor antagonist. To determine if 5-HT exerts any presynaptic effects on GABAergic and glutamatergic inputs, the actions of 5-HT on synaptic currents were studied. At 10 microM, 5-HT increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) but had no effect on both the frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs). However, 5-HT at a higher concentration (50 microM) decreased the frequency but not the amplitude of the mIPSCs, indicating an inhibition of GABA release from the presynaptic terminals. This effect was sensitive to 5-HT(1B) receptor antagonist. In addition to the presynaptic effects on GABAergic neurotransmission, 5-HT at 50 microM had no consistent effects on glutamatergic neurotransmission, significantly increased the frequency of miniature excitatory postsynaptic currents (mEPSCs) in 4 of 11 neurons and decreased the frequency of mEPSCs in 3 of 11 neurons. In conclusion, we found that 5-HT could modulate the excitability of globus pallidus neurons by both pre- and post-synaptic mechanisms. In view of the extensive innervation by globus pallidus neurons on other basal ganglia nuclei, this action of 5-HT originated from the raphe may have a profound effect on the operation of the entire basal ganglia network.

The proNGF-p75NTR-sortilin signalling complex as new target for the therapeutic treatment of Parkinson's disease.

Growing evidence has shown that the p75 neurotrophin receptor (p75NTR) may play important roles in controlling neuronal survival or cell apoptosis within the central nervous system in development, and in pathological or neural injury. Recent studies have further revealed that p75NTR acts as a "molecular signal switch" that determines cell death or survival by three processes. First, pro-nerve growth factor (proNGF) triggers cell apoptosis by its high affinity binding to p75NTR, while NGF induces neuronal survival with low-affinity binding. Second, p75NTR mediates cell death by combining with co-receptor sortilin, whereas it promotes neuronal survival through combination with proNGF. Third, release of the intracellular domain chopper or cleavaged "short p75NTR" can independently initiate neuronal apoptosis. We have identified the cell self-destructive proNGF-p75NTR-sortilin signalling apparatus assembled in ventral tier dopamine neurons of the substantia nigra pars compacta, suggesting that p75NTR signalling might be involved in selective cell death mechanisms of substantia nigra neurons or disease progression of Parkinson's disease (PD). In addition, experimental manipulation of p75NTR benefited cell survival of cholinergic or motor neurons and improved disease progression of the neurodegenerative diseases Alzheimer's disease and Amyotrophic lateral sclerosis. The proNGF-p75NTR-sortilin signalling complex may thus provide new target for neuroprotection of substantia nigra neurons and the therapeutic treatment of PD.

Angiomodulatory and neurological effects of ginsenosides.

Panax ginseng C.A. Meyer, one of the most popular and valued herbs, has been used extensively in traditional Chinese medicine for thousands of years. More than thirty ginsenosides, the pharmacologically active ingredients in ginseng, have been identified with various sugar moieties attached at the C-3, C-6 and C-20 positions of the steroidal skeleton. We herein review the current literature on the pharmacological effects of ginsenosides on the modulation of angiogenesis, dysregulations of which contribute towards many pathological conditions. Regarding the adaptogenic property of ginseng, the effects of ginsenosides on central nervous system are also discussed. Recent researches have pointed to the steroid hormone receptors as the target molecules to elicit the diverse cellular and physiological activities of ginseng. We believe that understanding the interaction between ginsenosides and various steroid hormone receptors may provide clues to unravel the secret of ginseng.

Neuroprotective effects of ginsenoside-Rg1 in primary nigral neurons against rotenone toxicity.

Ginsenoside-Rg1, the pharmacologically active component isolated from ginseng, demonstrated neuroprotective effects on primary cultured rat nigral neurons against rotenone toxicity. Rotenone, a common household pesticide known for its specific and irreversible mitochondria complex I inhibition, has been suggested to be the causal agent of Parkinson's disease (PD) by inducing degeneration of cells in the substantial nigra. The present study demonstrated that co-treatment of rotenone and Rg1 could reduce rotenone-induced cell death by 58% (SEM=+/-5.60; N=3). Rotenone-induced mitochondria membrane potential (MMP, DeltaPsim) depletion was restored and elevated by at least 38% (SEM=+/-2.15; N=3) by Rg1. In addition, Rg1 prevented cytochrome c release from the mitochrondrial membrane and increased the phosphorylation inhibition of the pro-apoptotic protein Bad through activation of the PI3K/Akt pathway. The protective effects of Rg1 was blocked by glucocorticoid receptor antagonist RU486, indicating that the action of Rg1 is mediated through glucocorticoid receptor (GR). In conclusion, Rg1 inhibits the mitochondrial apoptotic pathway and increases the survival chance of the primary cultured nigral neurons against rotenone toxicity. Thus, Rg1 and its related compounds may be developed as protective agents against neurodegenerative diseases induced by mitochondrial toxins.