AP Biology class blog for discussing current research in Biology

Tag: cell comunication

Memory Card Plugged in for Future Generations of Bacteria?

E. coli BacteriaHave you ever thought about the ability of being born with knowledge? It sounds like a plot out of a science fiction novel, yet recent research discovered that Escherichia coli (E. coli) bacteria, despite not having a brain, are able to remember past encounters with nutrients and pass this information down to their future offspring. This discovery not only surprises microbial behavior scientists but also reveals the challenge behind the fight against antibiotic resistance.

Swarming of Bacteria
George O’Toole, a microbiologist at Dartmouth College, explains that while “we typically think of microbes as single-celled organisms,” they actually operate in collective units or swarms. Interestingly, when they move in swarms, they become stronger against Antibiotics because there are more of them close together. According to this article from Missouri Department of Health and Senior Services that explain what is Antibiotic resistance, the reason E. coli bacteria become stronger against antibiotics when they are close together in swarms is due to their biological mutations, DNA exchange, and rapid reproductions. Mutations are essential to evolution, they can bring genetic variation (good or bad) to a specie. Because of the vast number of bacteria present and their high reproduction rate, many mutations can occur in a swarm of bacteria. Through random mutations and selection, bacteria can develop defense mechanisms against antibiotics. After some bacteria have developed some anti-antibiotic genes, bacteria will actively swap bits of DNA among both related or unrelated species. Thus, antibiotic-resistant genes will spread rapidly among a swarm of bacteria and can can even be incorporated into other species of bacteria. Finally, given the fast reproduction speed of bacteria, it does not take long for the antibiotic-resistant bacteria to fill up a huge portion of the bacteria population, therefore disabling/nerfing the effects antibiotic drugs.

Collective Memory of E. coli
A team of scientists, as reported in the Proceedings of the National Academy of Sciences USA, found that E. coli bacteria swarms have a form of memory that correspond to their exposure to nutrients. This experiment, led by Souvik Bhattacharyya from the University of Texas at Austin, observed unusual patterns in E. coli colonies. Through deeper examination with his science team, they concluded that these bacteria acted differently because of their previous experiences. Specifically, bacteria from colonies that had swarmed before were more likely to swarm again. This behavior was passed down to their descendants for four generations, suggesting a genetic memory of past actions in the bacteria.

Diagram of a gene on a chromosome CRUK 020.svg
By Cancer Research UK – Original email from CRUK, CC BY-SA 4.0, Link

Genes that are Responsible for this Behavior:
Further investigation was conducted to this phenomenon concluded that two genes responsible for iron uptake and regulation is the keys to bacteria’s memory. Bacteria with lower levels of iron, an essential nutrient for them, are more likely to move collectively(in swarms) to find environments with higher level of iron concentration. In addition to the past research that shown that many bacteria can remember and pass to their offspring of the description of their physical surroundings, this study suggests that bacterial can also remember and pass to their offspring about nutrients’ presence. This ability of bacteria to remember and pass on knowledge about physical surroundings and nutrient existence demonstrates bacteria’s evolution journey. 

This research increases our understanding of microbial life, showing that bacteria like E. coli can remember more the physical environments and can also recall the presence of nutrients. These memories will affect their decisions on where to settle and can increase their chances of surviving and fitness. O’Toole believes that this mechanism of bacterial memory is probably not exclusive to E. coli; it can actually be a common mechanism that exists among many different types of bacteria. The insights gained from studying these E. coli at a molecular level can provide valuable context for the development of antibiotics, offering new approaches as traditional antibiotics will eventually lose their effectiveness. 

Connection to AP Bio
In AP Biology, we’ve learned about Cell Signaling molecules and mechanisms used by organisms. Bacteria can also communicate amongst them when they are close together through a process called Quorum Sensing. Bacteria will secrete small chemical signaling molecules which will be detected by other bacteria nearby using their receptors. Through Quorum Sensing, bacteria are able communicate with others of their kind, sharing information about bacteria density and adjust gene expression accordingly. In addition, we will also be covering information about DNA, Heredity, and Evolution during this year in AP biology, which are also significant themes in this post. Numerous mutations will occur in swarms of bacteria due to their large number, this mutation of their DNA can occasionally cause significant change. If this change is extremely positive and can do this bacteria good, through natural selection, this gene will be kept and pass on to future generations of bacteria so that more and more bacteria will have this trait. This is the reason behind my antibiotics are slowly losing their functions. More and more bacteria have mutated and can resist the effects of antibiotic drugs.

What are your thoughts?
A couple of years ago, I often watched cartoons that portrays a type of technology that can give knowledge and pass memory to a newborn baby. I thought that it was a fascinating and unrealistic idea. However, during my research, I surprisingly found out that bacteria seemed to have this ability to pass on their memories to their offspring. What are your views about bacteria’s ability to memorize and pass their memories on to future generations? Do you think this experiment is helpful to future development of antibiotics? Feel free to leave a comment below and we can discuss more about this topic! For more information on this post, go to for the latest research and updates.

Individual Cells Move Differently When They Are Together

In a groundbreaking study, researchers have unveiled that a protein crucial for powering movement in individual cells operates distinctly when cells collaborate in groups. Cells engage in intricate pushing and pulling interactions with each other and surrounding tissues during processes such as embryonic organ formation, wound healing, pathogen pursuit, and cancer dissemination. The investigation, led by researchers at NYU Grossman School of Medicine, focused on a cluster of 140 cells known as the primordium, observing how these cells generate forces while adhering to each other during movement in zebrafish embryos—a model organism highly valued for its transparency and shared cellular mechanisms with humans.

The study reveals the role of a protein called RhoA, a primary structured protein, in propelling the group forward during embryonic development. As cells strive to move, they extend protrusions and utilize them to anchor onto nearby tissues before retracting them, a process analogized to the casting out and hauling in of an anchor.

Blood Anemia.jpg

In AP Biology, delving into the intricacies of the RhoA protein offers a compelling view of the relationship between structure and function in molecular biology. The distinct domains within RhoA, such as the GTPase domain, Switch I and II regions, insert region, and C-terminal hypervariable region, serve as structural modules that underpin its role as a molecular switch in cellular signaling. The GTPase domain’s proficiency in binding and hydrolyzing GTP is pivotal, causing RhoA’s influence on the cytoskeleton and, consequently, cellular processes like shape modulation, adhesion, and motility. The activation and inactivation, regulated by proteins like guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), displays these cell signaling pathways. RhoA’s dysregulation is a key player in diseases, displaying its integral contribution to maintaining cellular homeostasis. RhoA protein is a monomeric protein, meaning it does not have a quaternary structure.

Senior study author Holger Knaut, PhD, an associate professor in the Department of Cell Biology at NYU Langone Health, expressed surprise at the finding, stating, “This finding surprised us because we had no reason to suspect that the RhoA machinery required to move groups of cells would be different from that used by single cells.”

Prior research had indicated that single cells move forward by activating RhoA at their rear ends, initiating a process involving the motor protein non-muscle myosin II, resulting in cell constriction and detachment from the underlying surface.

Contrary to this, the current study revealed that cells in the primordium activate RhoA in pulses at the front of the cells, where it performs a dual role. At the front tip, RhoA stimulates the outward growth of the cell skeleton (actin meshwork), forming protrusions that grip the surface. Simultaneously, at the base of these protrusions, RhoA triggers non-muscle myosin II to pull on the actin meshwork, retracting the protrusions. This coordinated action propels the cell group forward, akin to the movement of a banana slug along the ground.

Dr. Knaut emphasized, “Our findings suggest that RhoA-induced actin flow on the basal sides of cells constitutes the motor that pulls the primordium forward, a scenario that likely underlies the movement of many cell groups.” He added that while the machinery suggests similarities in the movement of single cells and cell groups, RhoA contributes differently in each case.

Dr. Knaut also noted that a deeper understanding of the mechanisms by which cell groups move holds potential in halting the spread of cancer. He remarked, “The machinery suggests that the movement of single cells and groups of cells is similar, but that RhoA contributes to that machinery differently in each case. Within moving cell groups, RhoA generates actin flow directed toward the rear to propel the group forward.” The study’s findings could guide the design of treatments aiming to block the action of proteins implicated in the spread of cancer.

I personally never knew, especially before taking AP Biology, that cells move together. I did know that they always work together, but not necessarily that they coordinate their movements as a collective entity. It’s fascinating to learn about the intricate processes that govern cellular behavior.

I’ve been particularly intrigued by the role of proteins in these cellular functions. For instance, considering the RhoA protein, what would happen if it misfolded or denatured within our bodies? How would our body react to such a disruption? My assumption is that the consequences could be severe, possibly even leading to a breakdown in essential cellular activities. Could it be so detrimental that it might result in death? I’m curious to hear your thoughts on this matter.

I’ve been contemplating the impact of extreme heat on protein structure. If the RhoA protein were to misfold or denature due to high temperatures, it seems logical that our cells might struggle to move effectively within the body. The idea that external factors like heat could influence such fundamental cellular processes is both intriguing and concerning.

I’m curious about the specific gene responsible for coding the RhoA protein. Are there any specific diseases associated with mutations in this gene? It seems like understanding the genetic aspect could provide further insights into potential health implications.



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