Cannabinoid biosynthesis using non-canonical enzymes

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Leptin Resistance in Vagal Afferent Neurons Inhibits Cholecystokinin Signaling and Satiation in Diet Induced Obese Rats

Background and Aims: The gastrointestinal hormone cholecystokinin (CCK) plays an important role in regulating meal size and duration by activating CCK1 receptors on vagal afferent neurons (VAN). Leptin enhances CCK signaling in VAN via an early growth response 1 (EGR1) dependent pathway thereby increasing their sensitivity to CCK. In response to a chronic ingestion of a high fat diet, VAN develop leptin resistance and the satiating effects of CCK are reduced. We tested the hypothesis that leptin resistance in VAN is responsible for reducing CCK signaling and satiation. Results: Lean Zucker rats sensitive to leptin signaling, significantly reduced their food intake following administration of CCK8S (0.22 nmol/kg, i.p.), while obese Zucker rats, insensitive to leptin, did not. CCK signaling in VAN of obese Zucker rats was reduced, preventing CCK-induced up-regulation of Y2 receptor and down-regulation of melanin concentrating hormone 1 receptor (MCH1R) and cannabinoid receptor (CB1). In VAN from diet-induced obese (DIO) Sprague Dawley rats, previously shown to become leptin resistant, we demonstrated that the reduction in EGR1 expression resulted in decreased sensitivity of VAN to CCK and reduced CCK-induced inhibition of food intake. The lowered sensitivity of VAN to CCK in DIO rats resulted in a decrease in Y2 expression and increased CB1 and MCH1R expression. These effects coincided with the onset of hyperphagia in DIO rats. Conclusions: Leptin signaling in VAN is required for appropriate CCK signaling and satiation. In response to high fat feeding

The effects of culture conditions on the biomass and protein yield of spirulina

This study sought to optimize conditions for culturing spirulina in terms of the nitrogen, carbon, and light sources. Spirulina was batch cultured for 7 days under different culture conditions. Results showed that urea can be used as cheaper and more ava

Speech-to-sign language virtual avatar translation

Effective communication is a fundamental human right, and it is essential for individuals who are deaf or hard of hearing to have access to the same information as hearing individuals. The communication barriers faced by hearing-impaired individuals have become increasingly evident, particularly in online settings such as virtual classrooms and video conferences. In response, this project proposes a speech-to-sign language virtual avatar translator that can be integrated into popular virtual communication platforms such as Zoom and Microsoft Teams. The proposed solution utilizes artificial intelligence and natural language processing techniques to convert spoken language into real-time sign language, thus providing hearing-impaired individuals with a means to communicate and comprehend information more effectively in online settings. A user study involving 73 students was conducted to evaluate the effectiveness and usability of the proposed solution and has shown success in demonstrating high levels of accuracy and user satisfaction. The working system offers a promising approach to enhancing the accessibility of virtual communication platforms for the hearing-impaired and has the potential to improve the educational experiences of a marginalized group of students.Bachelor of Engineering (Electrical and Electronic Engineering

A biorefinery for Nannochloropsis: induction, harvesting, and extraction of EPA-rich oil and high-value protein

Microalgae have been studied as biofactories for almost four decades. Yet, even until today, many aspects of microalgae farming and processing are still considered exploratory because of the uniqueness of each microalgal species. Thus, it is important to develop the entire process of microalgae farming: from culturing to harvesting, and down to extracting the desired high-value products. Based on its rapid growth and high oil productivities, Nannochloropsis sp. is of particular interest to many industries for the production of high-value oil containing omega-3 fatty acids, specifically eicosapentaenoic acid (EPA), but also several other products. This review compares the various techniques for induction, harvesting, and extraction of EPA-rich oil and high-value protein explored by academia and industry to develop a multi-product Nannochloropsis biorefinery. Knowledge gaps and opportunities are discussed for culturing and inducing fatty acid biosynthesis, biomass harvesting, and extracting EPA-rich oil and high-value protein from the biomass of Nannochloropsis sp

Development of high‐level omega‐3 eicosapentaenoic acid (EPA) production from Phaeodactylum tricornutum

Phaeodactylum tricornutum is a lipid-rich marine diatom that contains a high level of omega-3 polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA). In an effort to reduce costs for large-scale cultivation of this microalga, this study first established a New BBM medium (0.3 x strength BBM with only 3% of the initial phosphate level) to replace the traditional F/2 medium. Phaeodactylum tricornutum could grow in extremely low phosphate concentrations (25\ua0µM), without compromising the EPA content. In the presence of sea salts, silicate addition was not necessary for high rate growth, high EPA content or lipid accumulation in this species. Using urea as the sole nitrogen source tended to increase EPA contents per dry biomass (by 24.7%) while not affecting growth performance. The use of sea salts, rather than just sodium chloride led to significantly improved biomass yields (20% increase) and EPA contents of total fatty acid (46-52% increase), most likely because it supplied sufficient essential elements such as magnesium. A salinity level of 35 led to significantly higher biomass yields compared to 20, but salinity had no significant influence on EPA content. EPA became the dominant fatty acid with average levels of 51.8% of total fatty acids during the exponential growth phase at 20 ppt in New BBM medium with sea salts

Effective harvesting of Nannochloropsis microalgae using mushroom ahitosan: a pilot-scale study

For efficient downstream processing, harvesting remains as one of the challenges in producing Nannochloropsis biomass, a microalga with high-value omega-3 oils. Flocculation is an effective, low-energy, low-cost method to harvest microalgae. Chitosan has been shown to be an effective food-grade flocculant; however, commercial chitosan is sourced from crustaceans, which has disadvantages including concerns over heavy-metal contamination. Thus, this study tests the flocculation potential of mushroom chitosan. Our results indicate a 13% yield of chitosan from mushroom. The identity of the prepared chitosan was confirmed by Fourier-transform infrared (FTIR) spectroscopy. Furthermore, results show that mushroom chitosan can be an alternative flocculant with >95% flocculation efficiency when tested in 100-mL jar and 200-L vertical column photobioreactor. Applications in a 2000-L raceway pond demonstrated that thorough mixing of mushroom chitosan with the algal culture is required to achieve efficient flocculation. With proper mixing, mushroom chitosan can be used to produce food-grade Nannochloropsis biomass suitable for the production of vegan omega-3 oils as a fish oil alternative

Cold and dark treatments induce omega-3 fatty acid and carotenoid production in Nannochloropsis oceanica

Nannochloropsis is one of the most-studied microalgae because of its high eicosapentaenoic acid (EPA) content and high-value carotenoids. However, during large-scale farming, decreased EPA productivity of Nannochloropsis oceanica BR2 was observed when cultured during the summer season (≥30 °C). We hypothesized that short low temperature treatments and membrane biosynthesis during reduced light exposure may increase EPA yields. Thus, we investigated the effect of 3-day cold or dark treatments on N. oceanica BR2 nutritional composition by measuring fatty acid and carotenoid profiles. Indeed, treated samples contained increased levels of polyunsaturated fatty acids including EPA and carotenoids violaxanthin and zeaxanthin. Tunnelling electron microscopy showed increased an chloroplast size and an increased number of thylakoid membranes in treated samples, visualizing how cells adapt to these environmental changes. The present study provides a practical strategy on how heat-stressed Nannochloropsis cultures can be subjected to short 3-day treatments before harvesting to enable high-value biomass production

Efficient harvesting of Nannochloropsis microalgae via optimized chitosan-mediated flocculation

Food-grade rather than synthetic or chemical flocculants are needed for microalgae harvesting by settling, if used for food products. Chitosan is effective in harvesting freshwater microalgae, but it is expensive and typically not suitable for marine microalgae like Nannochloropsis. To minimize costs for food-grade flocculation, a number of potentially important parameters are considered, including chitosan solubility and optimized chitosan-mediated flocculation of Nannochloropsis sp. BR2 by a five-factor central composite design experiment. Results show that an optical density (440 nm) of 2 (0.23 g dry weight L-1), initial pH of 6, final pH of 10, and 22 ppm chitosan with a viscosity of 1808 cP provide optimum flocculation efficiency, which is predicted to be in the range of 97.01% to 99.93%. These predictions are verified on 4.5 and 8 L Nannochloropsis sp. BR2 cultures