Gardner, Timothy S., Charles R. Cantor, and James J. Collins. "Construction of a genetic toggle switch in Escherichia coli." Nature 403, no. 6767 (2000): 339-342. The authors demonstrated the ability to create a stable toggle switch that could be controlled via external signals. The toggle switch consisted of two genes, each transcribing a repressor that inhibits the other gene’s promoter. That is, the expression of repressor 1 inhibited promoter 1 and therefore the transcription of repressor 2. With the brief introduction of an external inducer, repressor 1 would be inhibited, causing promoter 1 to transcribe repressor 2 to inhibit promoter 2. This idea worked in both directions. The external inducer for one repressor was chemical, IPTG, and the other was thermal, the application of heat. Once toggled, the switch was stable and would not randomly flip states. The state of the switch was visualized by Green Fluorescent Protein being transcribed downstream of one of the repressors, with the on state being fluorescent, and the off state indicated by the lack of fluorescence. Switches are the fundamental unit of electrical engineering, allowing the creation of Boolean logic gates which form the foundation of all modern digital computation. This paper was one of the first examples of the design of a non-naturally derived genetic network for basic logic. Elowitz, Michael B., and Stanislas Leibler. "A synthetic oscillatory network of transcriptional regulators." Nature 403, no. 6767 (2000): 335-338. Using a similar approach to the toggle switch, here an oscillating pathway was designed through the repression of three promoters, and dubbed the “Repressilator”. Rather than the stable states produced by mutual repression between gene... ... middle of paper ... ...lso designed to bind with nickel nitrilotriacetic acid-conjugated gold particles (NiNTA-AuNPs) via histidine side-chains on the amyloid monomers. Using the gold nanoparticle bound fibrils they were able to produce a conductive biofilm. They also created fibrils that bound quantum dots (QDs), and were able to modulate the fluorescence properties of the QDs by patterning QD bound monomers with the gold nanoparticle bound monomers, demonstrating an avenue for tuning attributes such as fluorescence intensity and lifespan. This research uses synthetic biology to achieve nanoscale synthesis of amyloid fibrils that can interface with inorganic materials such as gold and zinc. Fine grained control over the production of versatile scaffolding opens a huge range of possible applications in biofabrication, with the potential for major impact in both industry and medicine.
al. (1994) explain that a complementary DNA for GFP produces a fluorescent product when expressed in E. coli cells as the expression of GFP can be used to monitor gene expression and protein localization in living things. In this experiment, the heat shock method will be used to deliver a vector (plasmid) of GFP to transform and grow E. coli bacteria. Four plates containing Luria Bertani (LB) broth and either –pGLO or +pGLO will have E. coli bacteria added to it. The plate containing –pGLO (no pGLO) and LB will show growth as ampicillin will be present killing bacteria but no glowing because no arabinose will be present for glowing to be activated, the same result will be seen in the plate containing +pGLO, LB and ampicillin.
coli after addition of inducer IPTG at different times. We can see from the graph that it does not cut the X axis at time 0. This is due to the fact that the lac operon was not induced by IPTG due to lack of time. The graph cuts the X axis at roughly 1 and a half minutes after adding IPTG. This indicates the time where lac operon was first induced because there was beta-galactosidase produced. From here we can deduce that production of beta-galactosidase does not take place immediately after adding IPTG but rather takes a while for all the expression staged to be passed by lac operon in order to produce beta galactosidase. From the graph we can see that for the control no beta galactosidase was produced. This is because the control contains water and the repressor was allowed to bind to the operator, causing the transcription process to initiate due to RNA polymerase II not binding to the operator. There is a positive linear relationship between the time of induction with IPTG and the amount of beta-galactosidase production in the tubes. IPTG acts as an inducer, stopping the repressor protein to bind to the operator region by binding to the repressor protein, This causes the lac operon to be
E. coli produces very rapidly; a single microscopic cell can divide to form a visible colony with millions of cells overnight (phschool.com). It is the preferred bacteria in most laboratories because it grows fast and easy, and can obtain energy from a wide variety of sources. Since the birth of molecular cloning, E. coli has been used as a host for introduced DNA sequences (biotechlearn.org.nz). In 1973, Boyer and Cohen showed that two short pieces of DNA could be cut and pasted together, and returned to E.coli.
Takahashi, Y., et al. “Analysis of Promoter binding by the E2F and pRB Families In Vivo: Distinct E2F Proteins Mediate Activation and Repression.” Genes 14 (2000): 804-816.
It is now possible to control specific cell types with high temporal and spatial precision in
Transcription factors are proteins that help turn specific genes "on" or "off" by binding to nearby DNA.
Circadian rhythms are endogenous and self sustaining in all animals and plants. These rhythms are present in the absence of environment clues such as light, temperature and social clues. In absence of clues, animals free run in constant darkness due to programmed genetic interactions. Some of the genes involve in this processes are Per, Clock and Cry. The expressions of these genes are tightly regulated at molecular level by proteins which bind to promoters and repressors to create a rhythm throughout the day. For example, bmal and clock bind to ebox region to produce cry and mper proteins (Hong and Chong, 2007). These proteins are concentration dependant which means high level binds to repressor region to avoid further transcription. Such oscillations work on close to 24 hour cycle in animals and plants. These processes occur without any environmental clues. In case the environment clues are introduced to animals, they tend to synchronize internal clock with external signals. One such example of synchronization is shown in dorsophilia which increase Tim protein at night and the presence of external light decrease the production of Tim protein. This results into phase delay in dorsophilia (Leuloup and Goldbeter, 2001).
Trafton, A. (2013, June 23). MIT News. Enhancing RNA Interference, pp. 1-2. Retrieved 12 16, 2013, from http://web.mit.edu/newsoffice/2013/enhancing-rna-interference-0623.html
Encyclopaedia of Molecular Cell biology and molecular medicine, Robert Meyers, 2004, Wiley (page 221/426/385/416/237/ 2224/5321/5414/8869)
46- Kozak M. Rethinking some mechanisms invoked to explain translational regulation in eukaryotes. Gene. 2006; 382: 1-11.
Web. 19 Apr. 2013. "Genetic Engineering." GRACE Communications Foundation. N.p., n.d. Web.
New Scientist 212.2835 (2011): 6. Academic Search Complete. Web. The Web. The Web.
Research done by Figueroa et al. (2013) has turned up an advance in the method of non-viral gene delivery utilizing gold nanoparticles (AuNP). In their work they have developed an exceptionally efficient way of transfection by experimentally improving certain desirable traits of the gold nanoparticle polyamidoamine (AuPAMAM) c...
Many gene transcription is either elevator or decrease in expression as adaptive response to contamination, in order to maintain the homeostasis. For example, one such is the response
Genetic Engineering is the deliberate alteration of an organism's genetic information (Lee 1). The outcome scientists refer to as successful entitles the living thing’s ability to produce new substances or perform new functions (Lee 1). In the early 1970’s, direct manipulation of the genetic material deoxyribonucleic acid (DNA) became possible and led to the rapid advancement of modern biotechnology (Lee 1).