The top three news stories of the week, as chosen by our resident students. This week’s top stories include trees as a possible replacement for street lights, a new type of stem cell and a new link between diet and immunity.

By Nicholus Joab Mukhwana

Trees as future self-powered street lights

Scientists at the Massachusetts Institute of Technology (MIT) have engineered plants that can produce enough light to read a book. They exploited the luciferin-luciferase, a natural system that is used by a wide range of organisms such as bacteria, dinoflagellates and some insects like fireflies to produce glowing light. In the presence of oxygen, luciferase catalyses the oxidation of an organic molecule called luciferin. In the firefly luciferase-luciferin reaction pathway luciferase catalyses the oxidation of D-luciferin to generate yellow-green photoemission in the presence of ATP, Mg2+, and O2.

The researchers designed three different chemically interacting nanoparticles with controlled size and surface charge targeting specific compartments of the leaf for light production while limiting the toxicity caused by the accumulation of substrates and byproducts. Firefly luciferase (a monomeric 61 kDa) was immobilised onto maleimide-functionalized 7 nm silica nanoparticles (SNP-Luc,) to increase its stability within a living plant and help it penetrate plant cell wall efficiently while intact. Luciferin was supplied in poly (lactic-co-glycolic acid) (PLGA) nanoparticle to limit its toxicity due to its accumulation in a free environment.

Finally, Chitosan tripolyphosphate (CS) carriers were used to release coenzyme A (CoA), which regenerated luciferase activity via a reaction with dehydroluciferyl-adenylate, an active inhibitor of light production. SNP-Luc was designed to enter leaf mesophyll cells and stomatal guard cells and localise near the organelles, chloroplasts, and mitochondria, where ATP generation is highest. PLGA-LH2 and CS-CoA which are larger were meant to be retained within the leaf mesophyll intercellular spaces as releasing the reagents to be subsequently transported through the cell walls and membranes.

By injecting these nanoparticles into the leaves of watercress plant and optimising the interactions, they were able to generate plants that produced light for almost four hours. These are fascinating findings, and further research could lead the application of bioluminescent plants in lighting homes and streets. Don’t we fantasise about seeing glowing trees instead of streetlamps or a pot plant replacing the desk lamp? The outcome could cut down the carbon emissions by a significant percentage. You can read more about the publication by following this link.


An illustration of the mechanism of nanoparticles leading to the production of light in nanobionic light-emitting plants. Image sourced from Kwak et al. published in Nano Letters


The discovery of human skeletal stem cells

Scientists from the University of Pennsylvania, Philadelphia, USA have reported the discovery of human skeletal stems cells that could revolutionise the treatment of bone fractures and age-related osteoporosis among the older adults.

By using the genetic signature of skeletal stem cells initially identified in the mouse by Single-Cell Transcriptome Analysis of Growth Plate and Diaphysis, the researchers were able to isolate human skeletal stem cells from foetal bones and the adipose tissue with similar progenitor markers. These stem cells were able to differentiate into bone (marker Lin- PDPN+ CD146+)  and cartilage (marker Lin- PDPN+ CD146 ¯) tissues. Researchers further established that these skeletal stem cells undergo clonal expansion in bone injury or fracture. Unlike the mesenchymal stem cells that can also differentiate into fat, muscle, connective tissue, and blood vessels, these skeletal stem cells were only able to form bone and cartilage tissue. The discovery may present a solution to the challenge presented by application mesenchymal stem/stromal cells tissue in stem cell therapy because they also differentiate into other unwanted tissues when injected in human.

The best part of the discovery is that these stem cells can be isolated from the adipose tissue which is readily available from liposuction procedures. The finding presents a milestone in the treatment of bone fractures and osteoporosis in seniors. You can read more about the research work from here.

An illustration of the skeletal stem cells lineage as published by Chan et al. in Cell. 


The link between metabolism and immunity

One of the non-invasive obesity treatment has been the targeting of inducers of satiety by the drug to promote weight loss and consequently mitigate obesity-associated diseases like diabetes mellitus and hypertension.  Nucleobindin-2 (Nucb2) is one of the genes thought to induce satiety, causing weight loss, and thus improving insulin sensitivity.  However, a group of researchers at Yale University have discovered an exciting function of Nucleobindin-2 (Nucb2) gene using deletion mutants in a mouse model.

Nucb2 deletion did not affect food intake or adiposity; instead, it caused insulin resistance in mice fed on a high-fat diet. Interestingly, the loss of Nucb2 in mouse macrophages followed by high-fat diet feeding led to inflammation and insulin resistance. It then follows that Nucb2 controls inflammation by regulating macrophage activation in adipose tissue.

Insulin resistance is highly linked to obesity and results indiabetes. Further studies could establish the possibilities of targeting Nucb2 by drug therapy to reduce insulin resistance in obesity and prevent diabetes. Detailed information on this research can be found by clicking here.

A figure summarising the effects of Nucb2 knock-out in mice as published in Cell Reports. The image was sourced from Ravussin et al.