Tracing the start of COVID-19 in GA

At a time when COVID-19 appears to be receding in much of Georgia, it’s worth revisiting the start of the pandemic in early 2020. Emory virologist Anne Piantadosi and colleagues have a paper in Viral Evolution on the earliest SARS-CoV-2 genetic sequences detected in Georgia. Analyzing relationships between those virus sequences and samples from other states and countries can give us an idea about where the first COVID-19 infections in Georgia came from. We can draw Read more

Reddit as window into opioid withdrawal strategies

Drug abuse researchers are using the social media site Reddit as a window into the experiences of people living with opioid addiction. Abeed Sarker in Emory's Department of Biomedical Informatics has a paper in Clinical Toxicology focusing on the phenomenon of “precipitated withdrawal,” in collaboration with emergency medicine specialists from Penn, Rutgers and Mt Sinai. Precipitated withdrawal is a more intense form of withdrawal that can occur when someone who was using opioids starts medication-assisted treatment Read more

CROI: HIV cure report and ongoing research

The big news out of CROI (Conference on Retroviruses and Opportunistic Infections) was a report of a third person being cured of HIV infection, this time using umbilical cord blood for a hematopoetic stem cell transplant. Emory’s Carlos del Rio gave a nice overview of the achievement for NPR this morning. As del Rio explains, the field of HIV cure research took off over the last decade after Timothy Brown, known as “the Berlin patient,” Read more

neural tube defects

Flexibility and forgiveness during embryonic development

Geneticist Tamara Caspary’s laboratory has a recent paper in the journal Development showing how a developing mammalian embryo can correct a mispatterned neural tube over time. Former Genetics + Molecular Biology graduate student Chen-Ying Su, now a postdoctoral fellow at the Fred Hutchinson Cancer Research Center in Seattle, is the first author of the paper.

A molecule called “Sonic Hedgehog” is needed for proper patterning of the brain, spinal cord and eyes – it provides signals to the cells in the embryo, telling them what to become. Mutations that enhance Sonic Hedgehog signaling can lead to neural tube defects, some of the most common birth defects in humans, while those that diminish it can lead to holoprosencephaly, malformations of the brain and face. However, the majority of neural tube defects such as spina bifida do not come solely as a result of genetics – doctors think that getting enough (and possibly, not too much) of the B vitamin folic acid can prevent most of them.

Red = motor neuron precursor, green = later motor neuron marker
Mutation of Arl13b causes expansion of motor neurons (B and J)
Later deletion causes temporary expansion (C), corrected two days later (K)

Su and her colleagues examined mouse development in a situation where patterning of the neural tube is disrupted for a short time, because of a deletion in a gene (Arl13b), which helps to carry out Sonic Hedgehog’s instructions.

If Arl13b is not working starting from the beginning of development, embryos have an expansion of motor neurons, at the expense of other types of cells. The mutation leads to an open neural tube as well as abnormal eye, heart and limb development. However, if the deletion of Arl13b occurs on the ninth day, the embryo can recover proper patterning over the next few days. Mouse pregnancies last roughly three weeks.

Caspary says that while the relationship between Hedgehog signaling and neural tube defects is complicated, her lab’s recent work “does help define the time window during which we could non-surgically correct neural tube defects in utero.”

“In addition, it points to the importance of what we call “plasticity”- that cells can make incorrect decisions and correct them if still in a competency window, much like we think of adolescence,” she says. “It hints at the promise of stem cell research, that cells might be coaxed into other fates even though they start expressing tissue-specific markers. And it shows that the embryo is still much better at it than we are in a tissue culture dish.”

Posted on by Quinn Eastman in Uncategorized 1 Comment