Pigs as Organ Donors: Index #9

A new study, published in Nature Biomedical Engineering, has brought xenotransplantation (from pigs to humans) one tiny step closer to reality.

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🧬Featured Research

100+ Promoters Dissected with Base-Pair Resolution (Open Access)

During my time at Caltech, I contributed to a study (led by Bill Ireland and Suzy Beeler) that was published in eLife this week. In this study, Bill and Suzy created an experimental tool, called Reg-Seq, that combines massively parallel assays with mass spectrometry to determine the nucleotide-by-nucleotide contribution to DNA binding energy for 100+ promoters. With this method, we can determine where transcription factors (activators and repressors) cling to DNA, and then use this information to design new promoters with predictable expression levels. There is also a suite of online resources that we created, including code, tutorials, and an interactive figure so that you can look at the data for 100+ E. coli promoters yourself.

Genetic Overhaul Brings Pigs Closer to Viable Organ Donors

Xenotransplantation (taking an organ from one animal to give to another) is an ever-present theme in fiction; it appears in writings by Kazuo Ishiguro and Neal Shusterman, for example. A new study, published in Nature Biomedical Engineering, has brought xenotransplantation (from pigs to humans) one tiny step closer to reality. Luhan Yang (co-founder of a xenotransplantation company) and George Church’s group collaborated on the study. The researchers first deactivated all porcine endogenous retroviruses in pigs, which is crucial to prevent cross-species transmission of the virus (which is infectious to humans). Then, they engineered the pigs to express nine human transgenes that “enhance the pigs’ immunological compatibility and blood-coagulation compatibility with humans”. Fiction is one step closer to reality.

CRISPR Detects Malaria, Including Asymptomatic Cases (Open Access)

The World Health Organization estimates that there were 228 million cases of malaria in 2018. Rapid, easy testing for malaria could go a long way in combatting this global threat (which has likely killed more people than any disease in human history). A new CRISPR-based system, developed by the Collins lab at MIT, can be used to diagnose the “four major pathogenic Plasmodium species”, and it can do it in 60 minutes with an astounding sensitivity. In the case of Plasmodium falciparum, they could detect a single parasite in about three microliters of blood. The study was published in PNAS. Read the Wyss Institute news piece, too.

Artificial Cells “Talk” to Mammalian Neighbors (Open Access)

Artificial cells are lipid spheres, usually packed with some protein and DNA, that can be programmed to carry out a simple task, like glow green or produce a protein from a DNA template. From a historical perspective, artificial cells have been quite simple until recently. Now, new research has taken these protean cells one step further, demonstrating the creation of artificial cells that can chemically communicate with mammalian cells under physiological conditions. Researchers in Trento, Italy and Alberta, Canada created the cells from POPC (a type of phospholipid) and cholesterol and packaged them with DNA templates to synthesize a neurotrophic factor. When these artificial cells sense a specific small molecule in their environment, they switch on their genetic program, synthesize the neurotrophic factor, and “send it” to a neighboring neuron, triggering neuronal differentiation. This study was published in Science Advances.

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September 17-21 was National Postdoc Appreciation Week, so instead of a thread on new research findings, I am instead sharing some important thoughts on the value of postdoctoral researchers. Check it out 👇