Team:SCAU-China/SafetyPage

MESEG

Safety

Safety is the first priority. SCAU-CHINA always pays attention to safety.



Biosafety
(cell fixation and semi permeable membrane)

Similarly, we also pay great attention to biosafety in order to prevent gene leakage. We hope to use sodium alginate embedding method for cell fixation. Sodium alginate as a carrier has good activity and good mass transfer effect, but alginate gel is low in mechanical strength and easy to break. It is easy to dissolve in solution containing high concentration phosphate and K+, Na+, Mg2+ and other cations (Zhang Changli et al., 2013). With the deepening of research, polyvinyl alcohol (PVA) was introduced into sodium alginate embedding method, which can ensure the excellent mass transfer performance of sodium alginate and enhance the mechanical strength of immobilized pellets (Xue Liang et al., 2009). We will use PVA and sodium alginate mixed fixation. In addition, we also designed a device in which we also installed cellulose acetate semi permeable membrane. Cellulose acetate semipermeable membrane due to its pore size (5 μm) which is smaller than the cell size of Chlamydomonas reinhardtii (10 μm). It is non-toxic to cells, so it is used to prevent cells from escaping and maintain the relative stability of the internal environment of the device. For more information, see the hardware page.




Biosafety (kill switch)

We also designed the suicide pathway, but for various reasons, we failed to carry out experimental verification.

Figure 1: Design of suicide switch


Due to the less attenuation of long wavelength light such as near-infrared light compared with short wavelength light in the environment, and because plants mainly use red light and blue violet light, infrared light has little effect on the growth of Chlamydomonas reinhardtii. So we choose near-infrared light as the trigger factor. In the device, we will use filters to filter out near-infrared light. Once the algal cells leaked into the environment, near-infrared light transformed Bphp1 into PR state and induced heterodimerization with Ppsr2. The nuclear localization signal (NLS) fused with Ppsr2 contributes to the translocation of heterodimers to the nucleus. The Bphp1 fusion interacts with tetO DNA repeats through the fused TetR. VP16 fused with Ppsr2 recruits the transcription initiation complex and triggers the transcription of suicide genes such as Staphylococcus aureus ribonuclease. Relevant regulatory elements have been successfully verified in mammals (Kaberniuk et al., 2016).




Biosafety (organisms)

We selected the single-cell green algae--Chlamydomonas reinhardtii CMJ30 strain, which has no pathogenicity to human body and exists in natural water. Relevant tests are strictly standardized in the laboratory to prevent the leakage of engineered Chlamydomonas reinhardtii . We also used yeast strain BY4741 and Escherichia coli DH-5α strain in the project. They were strictly operated in the hood in the laboratory without any leakage. Please refer to the security form for more details.




Lab safety

In the laboratory, we pay close attention to the use of toxic reagents, such as nucleic acid dyes. We strictly follow the experimental operation specifications. There has never been a laboratory safety accident. The laboratory is equipped with safety equipment for different situations, eye and whole-body shower, fire extinguisher and first-aid box, and emergency exit. Please refer to the security form for more details.




Covid-19

From May 2021 to June, the outbreak of COVID-19 delta variant virus occurred in Guangzhou China. Fortunately, under the leadership of the government and the Communist Party of China, we have successfully overcome the epidemic. During the epidemic, we kept social distance, insisted on wearing masks, and actively cooperated with large-scale nucleic acid testing to ensure our own safety.




References

  1. Kaberniuk, A.A., Shemetov, A.A., and Verkhusha, V.V. (2016). A bacterial phytochrome-based optogenetic system controllable with near-infrared light. NAT METHODS 13, 591-597.
  2. 薛亮, 黄祖新, 罗招城, 曹翠辉, 陈由强, and 陈如凯. (2009). 海藻酸钠-PVA固定化酿酒酵母制备工艺的优化. 酿酒科技, 27-30.
  3. 张长利, 王景晶, and 杨宏. (2013). 细胞固定化技术研究进展及其在水处理领域的应用. 水处理技术 39, 1-4.