Closed JulietteB-cri closed 3 years ago
JulietteB-cri
commented
3 years ago Meile, S., Kilcher, S., Loessner, M. J., & Dunne, M. (2020). Reporter Phage-Based Detection of Bacterial Pathogens: Design Guidelines and Recent Developments. Viruses, 12(9), 944.
JulietteB-cri
commented
3 years ago Teresa R. de Kievit, Barbara H. Iglewski
(https://iai.asm.org/content/68/9/4839#sec-1)
24/03/2021
This review is studying some pathogenic relationships focusing on bacteria with a quorum-sensing system.
Quorum sensing (QS) Cell-to-cell communication so-called quorum-sensing can be defined as the capacity to detect the cell density and as a response to regulate gene expression. Many species of bacteria has this system, for example Gram-negative bacteria (below).
Gram-negative bacteria They are mostly using N-acyl homoserine lactones (AHL) as a signalling molecule. ==> when AHL in high concentration, they can induce gene expression by binding to and activating a transcriptional activator (R protein)
Biosensors: usually QS-controlled promoter fused to a reporter (e.g lux operon). These strains lacks the AHL synthase meaning that promoter activity depends on exogenous AHL.
AHL molecule signal molecules interacts and modulate the host immune response.
EXPLOITING BACTERIAL QUORUM SENSING
CONCLUSION:
JulietteB-cri
commented
3 years ago https://mmbr.asm.org/content/mmbr/77/1/73.full.pdf
Exploiting Quorum Sensing To Confuse Bacterial Pathogens (LaSarre et al. 2013)
JulietteB-cri
commented
3 years ago Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4718764/pdf/nihms732216.pdf
One sentence summary: The authors developed two genetic gene circuits able to kill efficiently E.coli, they can be reprogrammable to for example modify their killing mechanism.
Goal: design a system that can passively activate a biocontainment system (kill switch) for engineered microbes.
How does it work? It uses a small molecule-binding TF to create a survival state i.e where a specific environmental signal will determine/influences the repression of toxin production. When the environmental signal is lost, the system switches to the death mode (production of toxin killing the cell). It uses toggle switch architecture (LacI and TetR mutual repression system) to make the kill switch more robust.
Details & Construction Alteration of the RBS strengths of LacI and TetR in order to favour TetR expression in a single-copy plasmid. aTc - TetR inhibitor- is needed to maintain the survival state, it will be used to block toxin expression (and therefore cell death)
This induced death was increased by combining control of toxin expression and targeting essential protein degradation.
Goal: Construct a hybrid transcription factor design to extend the modularity of the system.
How does it work? The systems use hybrid LacI-GalR family TFs to expand the range and complexity of environmental signals used to define biocontainment conditions.
- Details & Construction
Both kill switch systems showed reduced killing efficiency over time. (escaped ones mainly showed inactivating mutations in the toxin genes). Proposition of the authors adding some additional killing systems into the circuits could reduce the decrease in killing efficiency.
Sabu, C., Henna, T. K., Raphey, V. R., Nivitha, K. P., & Pramod, K. (2019). Advanced biosensors for glucose and insulin. Biosensors and Bioelectronics, 141, 111201.
24/03/2021
Review of the different types of biosensors for glucose and insulin continuous monitoring.
Glucose and insulin are two central indicators to monitor & control the diabete - a chronic metabolic disorder. Insulin has a key role in glucose metabolism. Main way to diagnose it is to estimate the glucose concentration in the blood.
An “uncountable number of biosensors” have been developed to monitor continuously glucose and insulin levels.
Different types of glucose biosensor:
Note. A lot has already been done in this field -and some new nanotechnologies are being developed, are really precise, reliable & efficient. It could be interesting some applications of multisensors to another field (e.g plant diseases)