Horizontal Gene Transfer: How parasites control insect host behavior

Published recently in the journal Current Biology, research from a study conducted by the RIKEN Center for Biosystems Dynamic Research has revealed that parasites likely manipulate the behavior of their host organisms using horizontal gene transfer. 

In general, many parasites control their hosts to ensure the survival and reproduction of their species. One example of such a parasitic species is the horsehair worm, born in water but migrating to dry land using aquatic insects. After being eaten by a mantis (terrestrial insect), the worm grows within the host, beginning to manipulate its behavior. Once fully matured, the horsehair worm prompts the insect host to jump into the water and drown to its death, allowing the parasite to complete its life cycle and reproduce. 

Interestingly, previous studies have indicated that the horsehair worm likely manipulates the host’s biological pathways to increase movement towards the light (and approach water) by mimicking molecules found in the hosts’ central nervous system. To better understand how they developed such a mimicry mechanism, researchers analyzed the whole-body gene expression in a Chordodes horsehair worm before, during, and after host manipulation. From this study, researchers found over 3,000 genes that were expressed more during manipulation and 1,500 that were expressed less. In contrast, gene expression in the mantis brain did not change whatsoever, indicating that the parasites were producing proteins that would manipulate the host nervous system. After further analysis, interestingly, it was found that over 1,400 hairworm genes that matched those found in their mantis hosts were absent in species with different hosts. From these findings, researchers concluded that the identified mimicry genes (linked with neuromodulation, light attraction, and circadian rhythms) were likely the results of multiple horizontal gene-transfer events from various mantis species during the evolution of horsehair worm species.

Considering that horizontal gene transfer is far more common in prokaryotes, it was rather interesting to see an application of this phenomenon in eukaryotic species. This was especially the case since it is a primary way through which bacteria evolve antibiotic resistance. In that sense, horsehair worms would likely make ideal model organisms to study the mechanism by which horizontal gene transfer occurs and allows molecular mimicry, advancing current scientific understanding of evolutionary adaptation.

Click here to view the ScienceDaily article release

Click here for more information regarding this research study

Is you brain controlling your face shape and behavior?

Turns out our brains might have even more control over us than we think. Based on a study led by LU Leuven and Stanford, our brain might be controlling more than our movements but our personalities and behaviors. They identified over 76 overlapping genetic locations that shape both our faces and brain, which can easily debunk several persistent pseudoscientific claims related to our face and what it says about us. Although there were already suspicions of this link, this thought was purely based on model organism researches and clinical knowledge of extremely rare conditions. Joint senior for this study, Professor Peter Claes said it all began when they, “set out to map the genetic link between individuals’ face and brain shape much more broadly, and for commonly occurring genetic variation in the larger, non-clinical population. In these previous studies, we analyzed 3D images of faces and linked several data points on these faces to genetic information to find correlations.”

For this newfound discovery, they relied on previous studies that provided them with 20,000 MRI brain scans and genetic information. The focus was placed "on variations in the folded external surface of the brain," this allowed for the identification of 472 genomic locations that have shaped our brains; meanwhile, 76 of these genomic locations are linked to the face shape.

Fortunately, by them doing further research on this genetic link, they discovered there was no genetic link with behavior or neuropsychiatric disorders. "Our results confirm that there is no genetic evidence for a link between someone’s face and that individual’s behavior. Therefore, we explicitly dissociate ourselves from pseudoscientific claims to the contrary. For instance, some people claim that they can detect aggressive tendencies in faces by means of artificial intelligence. Not only are such projects completely unethical, but they also lack a scientific foundation," Professor Claes clarifies. This is a very interesting study. Our brain is already so powerful, to think that it'll be strong enough to have such a genetic hold on us would honestly be very surprising.

Links:

https://scitechdaily.com/genetic-link-discovered-between-face-and-brain-shape/

https://www.nature.com/articles/s41588-021-00827-w

Collective behavior and genes

 

In nature, animals live or travel in groups for many reasons. While this serves many evolutionary and survival advantages for a species, why do animals choose to live in groups? In the article, "Genetic control of collective behavior", a group of researchers at Harvard investigated this question to understand if genes play a role in guiding collective behavior. They began this research by focusing on mutations in genes associated with social behavior, such as autism or schizophrenia. Researchers observed that group behavior was altered in fish that specific gene mutations linked to human neuropsychiatric diseases. For example, zebrafish are found in groups or schools. Mutations affecting a group of fish show some fish were either scattered or separated from the group.

This article highlights some of the most common neuropsychiatric conditions that we see in society. The research talked about in the article mentioned earlier has allowed us to understand neuropsychiatric disorders on a deeper level. Especially for understanding how these diseases originate and impact behavior in affected individuals. Known how behavior can be affected can help with the management and treatment as well. Furthermore, by linking genes related to these conditions can help us get a step closer to possible cures. 

Another Excuse to Skip the Gym Today?

Are you one of those people who will find any excuse to avoid getting in a workout?  Well, this behavior might actually be in your genes.  According to researchers, anywhere from 20% to 60% of physical activity tendencies can be passed down to the next generation.  They found that the genes that control dopamine levels may effect a person's attitude toward exercise, whether they love it or hate it.  Dopamine is a neurotransmitter that effects a person's drive, pleasure, and reward centers of the brain.  So in conjunction with other behavioral traits and social influences there can be an indirect effect on levels of physical activity.

As someone who absolutely loves exercise it made me wonder if there were any genetic links to why that is.  After reading about the study it makes a lot of sense that it would be related to neurotransmitters that effect mood and motivation.  I've grown to love it so much because it's an escape, or an outlet, to clear things from my mind that are bothering me and to release negative feelings..

Genes underlying dogs' social ability revealed

According to a study done by Linköping University, the social ability of dogs is affected by genes that also seems to influence the way they behave with humans. The scientists involved in the research have found a relationship between five different genes and the ability of dogs to interact with humans.

Of all the domesticated animals, dogs are the oldest. Over thousands of years, they have adapted to a life among humans; through developed unique abilities to communicate and cooperate with humans. In this respect, they are widely superior to their wild ancestors, the wolves. If a dog was facing a difficult task, it'd most likely seek a human, apparently to solicit help. In similar situations, wolves generally attempt to solve the problem themselves.

"Our findings are the first to reveal genes that can have caused the extreme change in social behavior, which has occurred in dogs since they were domesticated," says Per Jensen, professor of ethology, who is the leader of the research group.

In the new study, the researchers wanted to study the behavior of the dogs by presenting them with an tough situation; opening a tight lid to obtain a treat. The participants included almost 500 beagles all with similar early exposure to humans. The scientists used video recordings to quantify the willingness of the dogs to seek physical contact with a person in the room when the problem turned out to be too difficult.The DNA of the dogs were also examined. By using a method called genome-wide association study or GWAS, the researchers examined a large number of genetic variants throughout the genome. GWAS can be used to find out if a particular genetic variant is more common among individuals with a particular trait, such as contact seeking behavior in this case. It turned out that the contact seeking dogs more often carried certain genetic variants.

I'm surprised to learn that behavior can be a result of a gene. This brings in the idea of nature vs. nurture which I find to be an interesting topic.

Why do we kill? Controversial study blames our distant ancestors

Recently, an experiment was conducted by José Gomez, Evolutionary Biologist at the University of Granada, to determine whether or not lethal violence was something that specific species of animals were predisposed to due to ancestors and evolutionary reasons, or if it was something they acquired individually.
Data from over one-thousand different species was collected to gain further insight into how many of these animals were killed by a member of the same species. A pattern emerged between animals that lived in groups and animals that lived on their own, showing that territorial group animals displayed higher incidents of lethal violence than animals that slightly isolated themselves from others of the same species.

Scientists then concluded that the more violent the species' ancestor was, the higher the chance of that species being lethally violent. According to the lethal violent rates in human ancestors, chimps, and bonobos, it was predicted that 2% of human deaths would be caused by other humans. Since primates live in groups that have a history of violence, the human rate of lethal violence was calculated using records from 50,000-10,000 years ago (hunter-gatherer time) and compared them to today's data. The percentage climbed to 12% as human settlements evolved and culture influenced violence.
Scientists not being able to clearly differentiate types of lethal violence when comparing species, as well as gathering a sufficient amount of data, created a hurdle in the experiment and the margin of error was taken into consideration by workers, with the intention of diving into more species in the future. The addition of more species, strengthens the validity of data and can aid in gathering a more solidified correlation. Identifying a correlation in behavior  of animals through genetics is an essential factor in gaining an understanding of the human race in relation to evolution and why humans do what they do.
http://www.sciencemag.org/news/2016/09/why-do-we-kill-controversial-study-blames-our-distant-ancestors

Genes underlying dogs' social ability revealed

Dogs were the first animal to be domesticated by humans, and it may have been as early as 16,000 years ago. In these thousands of years spent together, both species have co evolved and changed their relationship from what it started out as.  Dogs were first domesticated by early humans to serve as a wet nurse and help care for young babies while the parents were off hunting and gathering.  Since then, dogs have developed much better abilities to communicate and cooperate with humans.  Dogs often times come to humans for help, whereas their ancestral wolf would rather find solutions on its own.  A new study published in Scientific Reports searched for any relationship between this change in behavior and the genetic makeup of the dogs.

human and puppy bonding together

The study observed 500 beagles with previous experience around humans, and then presented the beagles with a problem. The problem was to open a sealed container that has food in it, and when they accepted it was too difficult, they observed if the beagles turned to human contact to solve the problem.  Of the 500 beagles studied, 200 of them were selected to have their DNA studied using a genome-wide association study (GWAS). The GWAS is able to find out if a particular gene variant is present in the dogs who exhibit a specific trait. A direct correlation was found using this method which determined that there actually were gene variants for the dogs who seeked human contact. Further support for this hypothesis would be if they performed this experiment on different dog breeds and still got similar results.

link to full article

Diversity of Autism Seen with Siblings

Autism is considered to be a complex disorder in brain development. Those who have autism usually experience difficulties with social interactions. Autism can even effect motor skills and health related thing such as gastrointestinal disturbances. The brain of a person diagnosed with autism acts differently than the brain of someone who does not have autism. Autism can causes its limitations but also it is known that a person suffering from autism may excel in skills such as math, or art to a higher level than someone without autism. It is a widely studied disorder that is still revealing new information on the effects of autism.

Two brothers both have autism yet behave differently.

Recently, genetic testing has been preformed on families that have more than one child with autism. It was found that siblings with autism

do not share the same genetic risk factors and are as distinct in their behavior as any brothers and sisters.

In this study 85 families who have two children diagnosed with autism were tested. By using whole genome sequencing technology the children's genome was mapped to identify every inch of their DNA to determine the relationship between the DNA of both children. It was found that only about 30 percent of the siblings shared the same genetic mutations while the remaining 70 percent did not. This is quite shocking because even in very closely related individuals the cause of autism and how the autism affects their behaviors are different. Those who shared the genetic mutations with their sibling showed similar behavior in their habits or skills compared to those that didn't have the same mutation. This study shows how diverse autism can be and why it is so difficult to understand. The study shows potential but needs to be expanded to more families to obtain a more accurate understanding of what it means to share or not share the genetic mutations. Hopefully in the future this kind of genetic mapping will help doctors determine a families risk of conceiving another child with the same disorder. Autism has a "mind of its own" so to speak, it causes different people to behave differently and with more genetic research the hope is to determine how the disorder does this and if anything can be done about it.

Not Magic, CADM2 is Why You Lost Your Virginity

Just today, Nature Genetics posted a "HUUUUGGEE" article as bernie would say with "25,000 participants, aged 40 to 69, from the UK Biobank, a national project that collected the DNA and personal information of half a million people in the UK from 2006 to 2010."

What did they find?  38 genetics variants that aren't magical at all, but are inherited and play a role into when people have sex for the first time. Contrary to previous belief, not all of them are linked with puberty.

Genes, such as CADM2, a risk taking gene has been found as a determinant factor in timing of one's first event so to speak. These genes is correlated with the age when Women had their first child as well as amount of children they had over their lifetime.

Environmental influences are not discredited by any means, as this study does acknowledge their role.

I found this interesting, because the argue of who we are because of nature vs nurture is not one which I believed to be applicable in the case of losing one's virginity. 

There are many cultural expectations with reproductions, which may be derived from genetics. This is a fascinating preliminary genetic analysis of a behavior that has taken place from the beginning of time.

This study will definitely advance a new viewpoint of science research, supplying answers in the form of genes for common practices that may be viewed as 

Perhaps now, genetics of rituals or other practiced mannerisms may be viewed analytically for genetic causation? Or does the persist of cultural behaviors weed out genes that don't possess similar genes deemed "right" by the society? 

Nature vs. Nurture, man..... 

Observing Bad Behavior can Cause Bad Behavior

Teens witness bad behavior through all types of ways. Whether they see it through video games, movies, or any type of social media they are exposed to it. Research was conducted to see if whether teens seeing bad behavior, such as drug or alcohol use, causes them to behave badly. The research was conducted by the Duke University lab. Most people understand bad behavior being copied, but it is not common though that the child may have a gene causing them to do so. The research found that there is a risk-taking gene that is associated with a sensitivity to substance abuse exposure.

I was surprised by the research. I knew that there are inherited traits when it comes to alcoholism, and addiction, but not just be observance. I think that it is interesting to learn that a gene can cause oversensitivity to topics such as seeing someone do drugs or drink. I knew that children from “broken” families tend to act out, but again I did not think there was a gene associated with that behavior. I would like to see more on this research as it advances.  

Epigenetic Marks Tied to Homosexuality

In a recent study of male twins, nine methylation sites helped researchers predict a person's sexual orientation. Throughout the study, it had been examined its genome and determining whether the individuals are methylated can peg sexual orientation with nearly 70 percent accuracy. The idea of epigenetics influencing sexual orientation had been proposed several years ago, but had been more recently examined in today's generation. Researchers had found that methylation status of nine regions in the genome could identify sexual orientation with a significant percent accuracy. Margaret McCarthy, a scientist at the University of Maryland School of Medicine stated, "This study provides a major step forward in our understanding of how the brain can be affected by factors outside of the genome. It is also possible that the experience of being a homosexual or a heterosexual has itself impacted the epigenetic profile. But regardless of when, or even how, these epigenetic changes occur, their findings demonstrate a biological basis to partner preference". It is also true that pinpointing the exact origins of this biological basis is a thorny issue. More work must be done to uncover the functional significance of the methylation profiles. Some scientists expressed caution in interrupting early data from a small study.

Additionally, twin studies and family trees provide strong evidence that sexual orientation is at least partially genetic. When one identical twin is gay, there is about 20% chance that the other will be as well. Due to the fact that this rate is not 100%, it is thought that environmental factors play a role as well and this can be characterized as the 'older brother effect', which is that chance is a man being gay increases by 33% for each older brother he has. This reason is not clear, but one hypothesis holds that the mother's immune system begins to react against male antigens and alter the fetus's development. In my opinion, I think a genome being able to tell if a person is homosexual or heterosexual is absolutely outrageous. I always believed a persons sexuality preference is their personal desire, not determined from a gene in your brain. I also think that the topic is not researched enough where it can prove this theory to be accurate.  

Link to article:

http://www.the-scientist.com/?articles.view/articleNo/44201/title/Epigenetic-Marks-Tied-to-Homosexuality/

Link to alternative article:

http://www.nature.com/news/epigenetic-tags-linked-to-homosexuality-in-men-1.18530

When it comes to mating behavior of the ruff its all in the genes

Using Genome sequences, researchers at the University of Sheffield have identified a 'super gene' that  determines the mating behaviors of certain ruff birds.  The ruff birds display three distinct types of mating behaviors: territorial males, non-territorial 'satellite' males, and 'cross dressing' males which mimic females.  A team of researchers identified a 'super gene' that contains a hundred or more genes which encodes for these distinct mating behaviors.  The researchers state the gene was created several million years ago due to chromosomal rearrangement which allowed the female mimics to coevolve with the territorial males.  They further state the alternative form of the super gene combined to give rise to the satellite males; the super gene encodes for multiple traits including hormones, feathering, color and size.

This article provides an interesting example of how genes can directly influence the behavior of animals and how the two ( genetics and behavior) are not mutually exclusive.  Furthermore this article also provides an excellent example of how evolution propagates the selection of advantageous  genes and how those genes are passed from one generation to the next.        

Men only think about "one thing", but is it really their fault?

        Don't worry boys; this study is not specifically about you. Male nematodes have a newly found pair of neurons in their brain.  Female worms do not have these neurons, which gives male worms extra brain cells. These neurons, "MCMs", enable male nematodes to have a higher recollection of sex and to desire it more.  MCMs stand for mystery cells of the male. Being sex-driven is not entirely in the control of male nematodes. In this experiment male worms possessing these "mystery cells of the male" and hermaphrodite worms were deprived of food and mating. After being conditioned to associate high salt concentration with sex and low concentration with food, the nematodes were set forth to pick one environment or the other. When finally given the free will to move into one of the new spaces, the male worms chose the environment with more salt. The male worms could have chosen to move towards food but they preferred being able to mate. Male nematodes desired sex more than their own survival (being able to eat after being starved). The hermaphrodite worms chose the lower concentration of salt associated with food. Another study was done with male nematodes that lacked the "mystery cells of the male". These males chose the food over mating. The MCMs must control the male nematodes' constant desire for sex.
      The difference in behavior is what has scientists and many others intrigued. Even a small worm can help us to comprehend the way humans behave. More studies like this one can add insight about gender identification, and sexuality in humans. Other studies are also being done to help us understand the behavior and genetic connections behind human sexual orientation. With each study, we are getting closer to breaking ground on why males and females behave so differently. I think this discovery is very interesting.  I did not expect the reason male nematodes to have extra brain cells. It might be far-stretched, but maybe there could be a similar explanation for human sexuality.
For the full article, visit here!

Altering Mosquito's Sense of Smell

On a hot summer day, hiking through a wet area, you find yourself being a plate of food for mosquitoes. By the end of the trip, you are covered in bug bites and the all you can think about it is cursing those damn mosquitoes. In a ScienceDaily article, it was reported that researchers have developed a way to alter an insect's sense of smell. Ocro was identified to be a gene that contributed to odor sensing in mosquitoes. When this gene was silenced, mosquitoes had difficulty sensing odors. Furthermore, the study showed that mosquitoes did not hold a preference toward a certain species (including humans). However, mosquitoes were shown to land on DEET (main component in bug repellent) covered subjects, but quickly fly away. Therefore, this indicates that there are multiple mechanism involved with sensing odors. All in all, orco was shown to interfere with an insect's receptors on sensing smells. As a result, future studies will dive deeper into understanding the other mechanisms involved with certain repellents and why mosquitoes prefer humans.

The Genetically Engineered Mosquito

The sense of smell is such an important way to retrieve information from our surroundings. It only took one gene to confuse a mosquito from its normal behavior. I believe that even though there is a genetically modified version of the mosquitoes that has no preference to humans, it would not survive in the wild due to the fact that humans are the most accessible type of nutrient for mosquitoes. Mosquitoes continue to favor Human for a reason. That is why the genes for this specific affinity were passed down. It was favorable to them, and those that could better sense Human odor better, survived more easily. 

Nicotine response genetics in the zebrafish

 



Tobacco use is predicted to result in over 1 billion deaths worldwide by the end of the 21^st century. How genetic variation contributes to the observed differential predisposition in the human population to drug dependence is unknown.Tobacco is a carrier for the highly addictive drug nicotine. Once your body gets a taste for nicotine, it can quickly become a life-long addiction, with extremely fatal consequences. Nicotine is the main drug in all forms of tobacco. Nicotine acts as both a stimulant and a sedative. It is one of the most heavily used addictive drugs in the U.S. The zebrafish is an emerging vertebrate model system for understanding the genetics of behavior. They developed a nicotine behavioral assay in zebrafish and applied it in a forward genetic screen using gene-breaking transposon mutagenesis. We show this insertional method generates mutant alleles that are reversible through Cre-mediated recombination, representing a conditional mutation system for the zebrafish. The combination of this reporter-tagged insertional mutagen approach and zebrafish provides a powerful platform for a rich array of questions amenable to genetic-based scientific inquiry, including the basis of behavior, epigenetics, plasticity, stress, memory, and learning. Looking at the figures below, the zebra fish were quite changed by the nicotine. 

Study Reveals that Hormones Influence Genes Controlling Gender Expression in Mice

The Scientist magazine and LiveScience.com both recently reported on a study conducted by Nirao Shah and his team at the University of California which was published this past Thursday in the journal Cell. The study suggested that when sex hormones turn genes in the brain on or off, certain behaviors are altered. The researchers focused on 16 genes in the hypothalamus of the mouse brain that are expressed differently between males and females and affected by the presence of sex hormones such as testosterone, estrogen and progesterone. Looking specifically at these 16 hormone-reactive genes, the researchers observed mice which lacked one of the genes to see if they demonstrated any abnormalities in some specific sexual or parental behavior. Female mice which lacked Cckar, a gene which influences feeding and metabolism, were far less responsive to the advances of males while their maternal instincts to care for and protect their pups remained normal. Females lacking Irs4, a gene affecting maternal protective instincts, were less defensive against intruders in the nest and less watchful of straying pups. Males missing the Tytl4 gene which regulates mating behavior still acted as normal males and impregnated females but their mating strategies were slightly altered. Male mice without the Brsr3 gene were more aggressive sexually and in defense against other males. Many researchers are already aware of the impact sex hormones have on behavior but little is understood about the mechanisms behind this process. This research suggests that certain behaviors can be traced to genetics. It may also suggest that hormones and genes in human brains react to construct certain behaviors and further study in this area could also help explain why certain mental illnesses such as autism and ADHD may affect females and males disproportionally.

Nature and Nurture: The Role of Epigenetic “Marks” on Chromosomes in Mental Illnesses

Recent research has shown that a person’s experiences may contribute to mental illness by causing epigenetic changes (as opposed to simply genetic influences), which turn genes "on" or "off" without changing the genes themselves. The causes for neurological problems like addiction, depression, autism, schizophrenia, and the like seem to be mostly genetic, but the addition of environmental factors such as drug use or high amounts of stress in a person’s lifetime play an equally strong role. The way our experiences are processed in the brain has to do with nerve cells, which exchange information by releasing and identifying chemicals called neurotransmitters. It has been discovered that neurotransmitters can activate or inhibit different nerve cells and then switch a group of responsive genes on or off -- over time, the particular genes a neurotransmitter affects can help in predicting how a nerve cell will respond to an experience, which then determines how an individual behaves.

[caption id="attachment_2748" align="alignright" width="239" caption="Image source: Nestler, Eric J. "Hidden Switches in the Mind." Scientific American Dec. 2011: 79. Print."][/caption]

However, the aforementioned effects of neurotransmitters on behavior are not permanent, which is why the role of epigenetic marks are so interesting in that they do cause more lasting behavioral changes. Essentially, these marks are chemical tags that are located on either DNA or histone proteins around which DNA is normally wrapped on genes, and they influence how tightly packed chromatin should be. (The more tightly wrapped DNA strands are around histone proteins, the more inactive genes are and the less likely they are to turn on. When a protein needs to be made, however, the section of DNA the gene that is needed to create it is on unfurls slightly so that it can be transcibed into a strand of RNA and the encoded protein can be produced.) These epigenetic changes are made by different enzymes, some of which add chemical tags, and others which remove them; researcher C. David Allis calls them the "writers" and "erasers," respectively, of the epigenetic code.

Studies have been done showing the impact of epigenetic markers on various types of behavior, including maternal behavior. These studies were conducted with rats and showed that epigenetically-affected behavior can be passed down in generations by affecting only the pups', or baby rats', brains because they are born with methyl marks on particular genes that enhance sensitivity to stress and if they are raised by relaxed, nurturing mothers, these methyl groups disappear and they are calmer pups and later, parents; however, if they are raised by passive, fearful mothers, then their genes actually acquire more methyl groups, and they grow up to be similarly passive, fearful parents themselves. Using this information is and will continue to be important in the future to improve methods for treating various psychiatric problems by developing drugs and attempting to ascertain to what degree epigenetic changes that occur with these psychiatric conditions are heritable.

For more information about the article used as the primary source for this post, listen to the author's own thoughts about it.