Papers by Keyword: Euglena gracilis

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Authors: Kazunari Ozasa, Jee Soo Lee, Simon Song, Masahiko Hara, Mizuo Maeda
Abstract: On-chip cytotoxicity sensing for liquid substances was investigated by using the microbial chemotaxis of Euglena gracilis. The Euglena cells were confined in a closed-type micro-aquarium in a PDMS microchip, and the micro-aquarium was isolated from two microchannels to flow test and reference liquid substances. Small molecules of liquids permeated into PDMS and diffused into the water in the micro-aquarium, and thus, the chemical concentration gradient of test liquids was built in the micro-aquarium. The negative chemotactic movements of Euglena cells were observed for ethanol down to 0.5% within 2-5 min after the injection of diluted ethanol into one of the separated microchannels (counter reference = pure water). On the other hand, when 0.5% H2O2 was introduced as a test liquid (counter reference = pure water), the Euglena cells fell into continuous rotation instead of single step turning and/or straight forward swimming. As a result, total swimming activity in the micro-aquarium decreased even after H2O2 flow was switched back to water. The observation shows that the types of cytotoxic effects can be identified through the cell movement analysis.
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Authors: Alex Mason, Kazunari Ozasa, Olga Korostynska, Ismini Nakouti, Montserrat Ortoneda-Pedrola, Mizuo Maeda, Ahmed Al-Shammaa
Abstract: Euglena is a naturally occurring algae which can be found in any fresh water source.It is non-toxic, easy to handle, visualize and relatively resilient to variation in environment.This, along with the relatively large size of Euglena, means it can be readily used as a modelfor environmental monitoring of other smaller pathogenic micro-organisms (e.g. Escherichiacoli ). Currently the behavior of Euglena is observed through the use of an optical microscopefor sensing purposes. However, this method su ers from following major pitfalls: (1) the sizeand expense of the microscope; (2) the small observation volume (approx. 1 L); (3) the imageprocessing requirements and (4) need for a skilled human operator to acquire those images. Byusing electromagnetic (EM) wave technology in the GHz frequency range we seek to overcomethese challenges, since it has been demonstrated by the authors to be cost e ective, have alarge sensing volume (> 100L) and produce comparatively simple output data. Furthermoreit is possible to use simple software algorithms to process the sensor output data, and providereal-time information on Euglena gracilis viability and quantity. This paper shows proof ofconcept work to verify the feasibility of the proposed EM wave technology as an alternative tothe current optical microscopy methods.
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Authors: Kazunari Ozasa, Jee Soo Lee, Simon Song, Mizuo Maeda
Abstract: We developed the real-time analysis of chemotactic motion of microbial cells (Euglena gracilis), for on-chip cytotoxicity sensing for environmental chemical substances. The Euglena cells were confined in a closed-type micro-aquarium in a PDMS microchip, and their movements were taken by a CMOS video camera. When 1.5%-H2O2 was introduced into a microchannel running aside of the micro-aquarium, the H2O2 molecules permeated into the micro-aquarium by diffusion through porous PDMS wall, and the cells fell into continuous rotation instead of single step turning and/or straightforward swimming. Such an abnormal swimming behavior is the result of metabolic disturbing effects evoked by radical oxygen species released from H2O2. In order to sensing the metabolic disturbing effects, we achieved real-time categorization of the swimming traces into straightforward swimming or continuous rotation; firstly the swimming traces in the video image were sectioned into squares, and then the aspect ratio and filling factor for each square were calculated. High aspect ratio or small filling factor corresponded to straightforward swimming, whereas low aspect ratio and high filling factor to continuous rotation. This motion analysis enables to measure the metabolic disturbing effects on swimming Euglena cells quantitatively, which is important to detect unidentified toxic substances in environments.
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