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When you just can’t find anyone to hang out with on a Friday night, it might not be a comfort to know that bacteria may have you beat when it comes to a social life.

“We now know that bacteria can lead complex social lives, communicating and cooperating within multicellular groups,” says Sam Brown, professor in the School of Biological Sciences and a member/past director of Georgia Tech’s Center for Microbial Dynamics and Infection (CMDI).

Getting out and about in the microbial world leaves bacteria facing challenges such as competition from other bacteria, threats from bacteria-eating viruses, drugs that target them, and starvation when they can’t find a host organism. Brown and his fellow CMDI scientists now want to know how bacteria modify their behaviors in response to their social and physical environments.

Two new grants totaling nearly $1.5 million will give them that chance.

One of the grants, a National Science Foundation award, focuses on how bacteria use clustered regularly interspaced short palindromic repeats — better known as CRISPR, a cellular immune system that helps bacteria ward off threats. CRISPR is perhaps best known as a gene editing tool.

The NSF grant also includes Rachel Kuske, professor in the School of Mathematics and a CMDI member, and Edze Westra, Professor of Microbiology at the University of Exeter in the United Kingdom. The NSF is partnering with the UK’s Biotechnology and Biological Sciences Research Council (BBSRC) for this grant.

The other grant from the Army Research Office (ARO) will study quorum sensing, a form of cell-to-cell communication, to determine how bacteria use it to “count” cells so that collective behavior can be turned on.

Both grants can help CMDI understand microbial behavior in ways that could eventually lead to manipulating or controlling bacteria, says Steve Diggle, CMDI director and a professor in the School of Biological Sciences.

“We are delighted by these new grants as they align closely with the core mission of CDMI because they will advance our understanding of microbial interactions, behaviors, and community dynamics,” Diggle says. “The knowledge generated could have transformative impacts on both academic research and practical applications.”

CRISPR protections, but only in a crowd

Brown wants to make it clear that he and his colleagues won’t be doing any CRISPR gene editing themselves. “Our questions are more basic, focused on how the ‘inventors’ of CRISPR, bacteria, use this system to protect themselves from infection by phages (viruses that attack bacteria) and other molecular parasites of cells,” Brown says.

CRISPR’s role is to recognize and cut out specific sequences of foreign DNA within bacteria. Yet what Brown calls the “dirty secret” of microbiology is that lab bacteria rarely use CRISPR to deal with novel viruses.

“Instead, they use the simple trick of deleting the surface receptors that the virus uses to gain entry to the cell,” he explains. Previous work by CMDI Early Career Award Fellow Ellinor Alseth found an answer to this puzzle: bacteria are more likely to use CRISPR as an immune mechanism when they are living in a multi-species community. What Brown hopes to decipher are the molecular and ecological mechanisms that determine how life in a community can activate CRISPR functions.

“We further aim to build mathematical models of community dynamics, capturing both species interactions and evolutionary changes in a focal species undergoing viral attack,” Brown says. “This will have applied significance by helping the design of more robust microbial communities.”

Quorum sensing = a bacterial census

Regarding the ARO grant, Brown says the standard view for quorum sensing is that bacteria use those signals as a way of counting cells. When the extracellular signal is above a certain threshold, the population is “quorate” (that is, reaches a certain number of cells), and collective behaviors can be turned on.

Yet an increasing body of theory, along with experiments in Brown’s lab and others, has challenged this view “by highlighting that quorum sensing behaviors can also be shaped by the physical environment, such as diffusion, flow rate, and containment,” he says.

Also, behaviors are not “turned on” in a threshold manner with increasing density. “In a high density ‘quorate’ environment, not all cells are expressing canonical quorum sensing-controlled behaviors. These challenges leave us with limited understanding of the functional roles of QS.”

“By examining the balance between intracellular mechanisms and multicellular behaviors, we will obtain a more comprehensive understanding of how bacteria collaborate and respond collectively to their environment,” Diggle adds.

Charles Darwin said that evolution was constantly happening, causing animals to adapt for survival. But many of his contemporaries disagreed. If evolution is always causing things to change, they asked, then how is it that two fossils from the same species, found in the same location, can look identical despite being 50 million years apart in age?

Everything changed in the past 40 years, when an explosion of evolutionary studies proved that evolution can and does occur rapidly — even from one generation to the next. Evolutionary biologists were thrilled, but the findings reinforced the same paradox: If evolution can happen so fast, then why do most species on Earth continue to appear the same for many millions of years?

This is known as the paradox of stasis, and James Stroud, assistant professor in the School of Biological Sciences at the Georgia Institute of Technology, set out to investigate it. He conducted a long-term study in a community of lizards, measuring how evolution unfolds in the wild across multiple species. In doing so, he may have found the answer to one of evolution’s greatest challenges.

His research was published as the cover story in the Proceedings of the National Academy of Sciences.

Read the full feature in the GT Research newsroom.

Charles Darwin said that evolution was constantly happening, causing animals to adapt for survival. But many of his contemporaries disagreed. If evolution is always causing things to change, they asked, then how is it that two fossils from the same species, found in the same location, can look identical despite being 50 million years apart in age?

Everything changed in the past 40 years, when an explosion of evolutionary studies proved that evolution can and does occur rapidly — even from one generation to the next. Evolutionary biologists were thrilled, but the findings reinforced the same paradox: If evolution can happen so fast, then why do most species on Earth continue to appear the same for many millions of years?

This is known as the paradox of stasis, and James Stroud, assistant professor in the School of Biological Sciences at the Georgia Institute of Technology, set out to investigate it. He conducted a long-term study in a community of lizards, measuring how evolution unfolds in the wild across multiple species. In doing so, he may have found the answer to one of evolution’s greatest challenges.

His research was published as the cover story in the Proceedings of the National Academy of Sciences.

Read the full feature in the GT Research newsroom.

Mosquitoes are some of the fastest-flying insects. Flapping their wings more than 800 times a second, they achieve their speed because the muscles in their wings can flap faster than their nervous system can tell them to beat.

This asynchronous beating comes from how the flight muscles interact with the physics of the insect’s springy exoskeleton. This decoupling of neural commands and muscle contractions is common in only four distinct insect groups.

For years, scientists assumed these four groups evolved these ultrafast wingbeats separately, but research from the Georgia Institute of Technology and the University of California, San Diego (UC San Diego) shows that they evolved from a single common ancestor. This discovery demonstrates evolution has repeatedly turned on and off this particular mode of flight. The researchers developed physics models and robotics to test how these transitions could occur.

Read the full feature in the GT Research newsroom.

Mary K. Holder, a senior academic professional in the School of Psychology and associate director of Georgia Tech’s Undergraduate Program in Neuroscience, is adding a new title to her CV: President of the Atlanta chapter of the Society for Neuroscience (ACSFN).

Holder will serve a three-year term for the organization, founded in 1976 to bring together neuroscientists working in the Atlanta area. The chapter promotes research and public understanding of the brain and nervous system by recognizing promising students and sponsoring lectures. The Society also organizes events such as Brain Awareness Month and the Atlanta Brain Bee, an annual competition for middle school and high school students who are tested on their knowledge of the brain and nervous system.

“I was surprised and honored to be asked to serve as the President for the ACSFN,” Holder says. “It’s an exciting opportunity to serve the greater Atlanta neuroscience community. I’m also a bit nervous as well, as I’ve never had this type of leadership position. I know that I’ll be relying a lot upon the council members of the ACSFN to help things run smoothly.”

One of Holder’s goals involves boosting the Society’s outreach to local and area K-12 schools, which were impacted by Covid-19 shutdowns — a time that the Georgia Tech neuroscience community also began talking more about the impact of historic exclusion, marginalization, and structural inequities in society and science, Holder says.

“One of the things I hope to accomplish as the new president of the Atlanta chapter is to foster meaningful engagements and partnerships so that outreach becomes something more authentic and collaborative,” she says. “I would love to be able to further support the winners of the Atlanta Brain Bee to go to the national competition without experiencing a financial burden.” Holder added that helping with competition fees would require increases in donations to the chapter.

About Mary Holder and Georgia Tech Neuroscience

Holder, a Georgia Tech alumna (B.S. PSYC ‘04 with High Honors), received her Ph.D. in Neuroscience in 2011 from the University of Maryland. Her research interests include neuroendocrinology, psychopharmacology, and behavioral neuroscience.

Since Georgia Tech began offering a neuroscience undergraduate degree in 2017, Holder notes that the Institute has experienced tremendous growth within the discipline. There are now approximately 500 neuroscience majors, and nearly 300 have graduated.

“In the past few years, we have made remarkable progress in our curriculum and course offerings to give a true Georgia Tech flavor to the neuroscience education for students,” she says. “Beyond the major itself, which is housed within the College of Sciences, there are neuroscientists all over campus.”

GTNeuro, a grassroots effort over many years, led to the hiring of faculty researching the brain, as well as the creation of the undergraduate neuroscience program. It also led to the September announcement of the Neuro Next Initiative, a foundational, interdisciplinary program to lead in research related to neuroscience, neurotechnology, and society.

“The Neuro Next Initiative should foster some fascinating opportunities for supporting collaborative research, educational missions, and public engagement,” Holder says. “I’m excited to see how the neuroscience programs and research will continue to grow and expand here. I think these new initiatives represent amazing opportunities for our students.”

Stephen (Nick) Housley, a postdoctoral scholar in the School of Biological Sciences, is the first recipient of an early career award through the Jack and Dana McCallum Neurorehabilitation Program.

Housley, who received his Ph.D. in Applied Physiology at Georgia Tech in 2020, has been awarded a Jack and Dana McCallum Early Career Award for postdoctoral researchers. The goal of the program is to strengthen research in neurorehabilitation and the relationship between Georgia Tech and Emory University. The program supports graduate students and will now also support some postdoctoral scholars through Early Career Awards.

Housley’s research intersects neuroscience and cancer biology. “I am genuinely honored to have my work recognized and acknowledged through [this] support,” Housley says. “The sort of high-reward studies that I pursue are often perceived as risky. Having this support will enable me to pursue ambitious projects and expand on the breadth of studies.”

The new award from alumnus and College of Sciences Advisory Board member Jack McCallum, M.D., Ph.D. (BIO ‘66) is part of a $1 million gift committed in 2022 for the creation of the Jack and Dana McCallum Neurorehabilitation Training Program facilitated by Georgia Tech and in partnership with Emory University and The Shepherd Center’s Crawford Research Institute. This funding will be used over the next two years to support graduate student, postdoctoral and faculty research, as well as train new scientists in neurorehabilitation.

The McCallum Family Foundation has previously provided scholarships to reward outstanding undergraduate students for their academic excellence and performance in Georgia Tech research labs. The McCallum scholarships enable undergraduates to engage in research earlier in their academic careers than many colleges and universities. And scientific research is a defining characteristic of the undergraduate experience in the School of Biological Sciences at Georgia Tech, where young undergraduate researchers are provided access to experienced faculty mentors and research labs with cutting-edge equipment, which are critical to their training as scientists.

About Stephen Housley

Stephen (Nick) Housley is a clinician-scientist focused on cancer neurobiology with specialty training in treating neurological disorders. Housley is also a fellow in both the Sensorimotor Integration Lab and the Integrated Cancer Research Center at Georgia Tech.

Housley’s research centers on how the nervous system, cancer, and its treatment interact in mammalian systems. “My research interests rest on my recent discoveries that securely establish the existence of reciprocal interactions between cancer, cancer treatment and the nervous system,” he explains. “In addition, my other area of study centers on how the nervous and musculoskeletal systems interact to encode sensorimotor information, and how integration in the mammalian spinal cord results in physiologically relevant movement.”

As part of his research into cancer neurobiology, Housley is also developing therapeutic nanohydrogels: microscopic polymer-based particles that may serve as next-generation drug delivery vehicles. “I have been exploring the use of my nanohydrogel platform to deliver therapeutic payloads to solid tumor cancers,” he says.

Housley wishes to thank M.G. Finn, who serves as professor and chair of the School of Chemistry and Biochemistry at Georgia Tech and James A. Carlos Family Chair for Pediatric Technology, for Finn’s mentorship and support of nanohydrogel research. Housley also thanks Timothy Cope and John McDonald, both professors in the School of Biological Sciences, “who provided the intellectual and practical environments focused on neuroscience and cancer biology. Their support enabled me to pursue a new research field at the intersection of both — namely, cancer neurobiology,” Housley adds.