These tiny fish are helping scientists understand how the human brain processes sound.
- Fragile X syndrome is a genetic disorder caused by changes in a gene that scientists call the "fragile X mental retardation 1 (FMR1)" gene. People who have FXS or autism often struggle with sensitivity to sound.
- According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain.
- Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information.
By disrupting a specific gene in Zebrafish, we're able to better understand the same disruption of that gene in humans with FXS or autism.
Credit: slowmotiongli on Adobe Stock<p>"Loud noises often cause sensory overload and anxiety in people with autism and Fragile X syndrome -- sensitivity to sound is common to both conditions," <a href="https://www.sciencedaily.com/releases/2020/11/201110102527.htm" target="_blank">Dr. Constantin explained to Science Daily</a>.</p><p><strong>How do zebrafish relate to humans with autism? </strong></p><p>According to the research team, FXS is caused by the disruption of a gene. By disrupting that same gene in zebrafish larvae, they can examine the effects and begin to understand more about this disrupted gene in the human brain. </p><p>The thalamus, according to Dr. Constantin, works as a control center, relaying sensory information from around the body to different parts of the brain. The hindbrain then coordinates different behavioral responses. Using the different sound tests, the team was able to study the whole brain of the zebrafish larvae under microscopes and see the activity of each brain cell individually. </p><p>According to Dr. Constantin, the research team recorded the brain activity of zebrafish larvae while showing them movies or exposing them to bursts of sound. The movies stimulated movement, a reaction to the visual stimuli that was the same for fish with the Fragile X mutation and those without. However, when the fish were given a burst of white noise, there was a dramatic difference in the brain activity of the fish with the Fragile X mutation.<br></p><p>After seeing how the noise radically affected the fish brain, the team designed a range of 12 different volumes of sound and found the Fragile X model fish could hear much quieter volumes than the control fish. </p><p>"The fish with Fragile X mutations had more connections between different regions of their brain and their responses to the sounds were more plentiful in the hindbrain and thalamus," <a href="https://www.sciencedaily.com/releases/2020/11/201110102527.htm" target="_blank">said Dr. Constantin</a>.</p><p>Essentially, the fish with Fragile X mutation had more connections between the regions of their brain and so their responses to the sounds were more notable. </p><p><strong>Understanding how this gene disruption works in zebrafish will give us a better understanding of sound hypersensitivity in humans with FXS or autism.</strong> </p><p>"How our neural pathways develop and respond to the stimulation of our senses gives us insights into which parts of the brain are used and how sensory information is processed," Dr. Constantin said.</p><p>Using the zebrafish, Dr. Constantin and the team were able to gather insights into which parts of the brain are used to process sensory information. </p><p>"We hope that by discovering fundamental information about how the brain processes sound, we will gain further insights into the sensory challenges faced by people with Fragile X syndrome and autism."</p>
A new study tracks the human-dog relationship through DNA.
- The earliest dog, not wolf, found so far comes from over 15,000 years ago.
- A new study tracks the travel and development of dogs since the end of the Ice Age.
- Insights are derived by comparing ancient canine DNA with ancient human DNA.
DNA gets around<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDY2NDU3NC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxNzkyNH0.K0JEM0y89zL-HIr_8Z_iPW-ypbebDjFBNjXAkPraqok/img.jpg?width=980" id="de25c" class="rm-shortcode" data-rm-shortcode-id="3bec27e152f342b23e248227e2697222" data-rm-shortcode-name="rebelmouse-image" />
Assyrian dog relief
Credit: Wikimedia Commons<p>The research is the product of a collaboration between Larson and paleogenomicist <a href="https://www.crick.ac.uk/research/find-a-researcher/pontus-skoglund" target="_blank">Pontus Skoglund</a> of the UK's Francis Crick Institute. Skoglund is an expert in canine evolution, working with teams at both institutions as well as the University of Vienna.</p><p>The researchers analyzed DNA from over 2,000 sets of canine skeletal remains, some of which dated back as far as 11,000 years. Working with ancient DNA from Siberia, Europe, and the Near East, the researchers were able to add 27 newly sequenced dog genomes to the previously sequenced five.</p><p>The researchers compared the canine DNA to the genomes of 17 human individuals who lived during the same time frames in search of common influences that might further establish their connection. Indeed, correspondences were seen that reflected the impacts of humans bringing their dogs along with them as they migrated around the world.</p><p>They found that Swedish farmers and their dogs are both descended from canines of the Near East, suggesting that man and dog followed the development of agriculture together through Europe. On the other hand, German farmers 7,000 years ago came from the Near East, but their dogs didn't.</p>
Lineages intersect<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDY2NDU3OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY1MjE0NDc3OH0.XLvmAchMESbLY0beM-j1NTR80JGvAWOsqzJeXjH6JGI/img.jpg?width=980" id="af19d" class="rm-shortcode" data-rm-shortcode-id="7ade8431e978b8bd5adfcecaa06697c7" data-rm-shortcode-name="rebelmouse-image" />
Credit: Sabine Schönfeld/Adobe Stock<p>Based on their analysis, the scientists assert that by 11,000 years ago, just after the Ice age, there were already five distinct families (or lineages) of dogs, so the German remains were no outlier. These lineages eventually developed into later lines.</p><p>Some of this occurred through interbreeding with other dogs and also through mating with their wild wolf cousins. Comparisons between ancient dog and wolf DNA revealed a surprise: Wolves picked up DNA from dogs, but, at least judging by the remains available, there was little or no gene flow back in the other direction. Larson <a href="https://www.sciencemag.org/news/2020/10/how-dogs-tracked-their-humans-across-ancient-world" target="_blank">suggests</a> to Science that the evidence may have been tampered with, so to speak — if a dog started behaving like a wolf, its human may well have simply gotten rid of it. </p><p><a href="https://www.crick.ac.uk/research/find-a-researcher/anders-bergstrom" target="_blank">Anders Bergström</a> is the lead author of the study, and he <a href="https://www.crick.ac.uk/news/2020-10-29_study-of-ancient-dog-dna-traces-canine-diversity-to-the-ice-age" target="_blank" rel="noopener noreferrer">points out</a> a mystery it reveals: "If we look back more than four or five thousand years ago, we can see that Europe was a very diverse place when it came to dogs. Although the European dogs we see today come in such an extraordinary array of shapes and forms, genetically they derive from only a very narrow subset of the diversity that used to exist." Why — and how — one line of dogs so dominated early Europe as to wipe out other lineages remains a mystery. The researchers found no human development that mirrors, or could explain, this event.</p>
A dog's life<p>It's fun to realize that ancient dog lineages persist to this day. It turns out Chihuahuas have traces of ancient American dogs, and Huskies bear traces of their cold-weather ancestors. Skoglund tells Science that on any given day in a modern dog park, you may be looking at lineages that date back 11,000 years.</p><p>It's likely that subsequent research will reveal even more. Says co-author and University of Vienna group leader Ron Pinhasi, "Just as ancient DNA has revolutionized the study of our own ancestors, it's now starting to do the same for dogs and other domesticated animals. Studying our animal companions adds another layer to our understanding of human history."</p>
"Such studies will lead to a better understanding of brain development in both autistic and typical individuals."
- Autism spectrum disorder (ASD) is a neurodevelopmental condition that can cause significant social, communication, and behavioral challenges.
- Although a diagnosis of autism can typically be made around the age of 2, the average age for diagnosis in the United States is after 4 years old.
- A new study shows that the atypical development of autism in human brain cells starts at the very earliest stages of brain organization, which can happen as early as the third week of pregnancy.
Nerve cells in the autistic brain differ before birth, new research finds<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="97bc70ff8b04dcea1a5e712e3789a970"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/JPO-uOPK5RI?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p><a href="https://www.sciencedaily.com/releases/2020/08/200824091958.htm" target="_blank" rel="noopener noreferrer">A new study</a> shows that the atypical development of autism in human brain cells starts at the very earliest stages of brain organization, which can happen as early as the <a href="https://www.enfagrow.com.sg/my-pregnancy/development/per-month/baby-brain-development-during-pregnancy#:~:text=Your%20developing%20baby's%20brain%20development%20technically%20begins%20during%20the%20third,%2C%20hindbrain%2C%20and%20spinal%20cord." target="_blank">third week of pregnancy</a>.</p><p>The study was performed by scientists at King's College London and Cambridge University. </p><p><strong>The study used induced pluripotent stem cells to recreate the development of each sample in the womb.<br></strong>The researchers isolated hair samples from nine autistic people and six typical people. By treating the cells with an array of growth factors, the scientists were able to drive the hair cells to become nerve cells (or neurons), much like those found in either the cortex or the midbrain region.</p><p>These induced pluripotent stem cells (referred to as IPSCs) retain the genetic identity of the person from which they came, and the cells restart their development as it would have happened in the womb. This provides a look into that person's brain development.</p><p>At various stages, the researchers examined the developing cells' appearance and sequenced their RNA to see which genes the cells were expressing. On day 9 of the study, developing neurons from typical people formed "neural rosettes" (an intricate, dandelion-like shape indicative of typically developing neurons). Cells from autistic people formed smaller rosettes (or did not form any rosettes at all), and key developmental genes were expressed at lower levels.</p><p>Days 21 and 35 of the study showed cells from typical and autistic people differed significantly in a number of ways, proving that the makeup of neurons in the cortex differs in the autistic and typically developing brains.</p><p>John Krystal, Ph.D., Editor-in-Chief of Biological Psychiatry, <a href="https://www.sciencedaily.com/releases/2020/08/200824091958.htm" target="_blank">explains</a>: "The emergence of differences associated with autism in these nerve cells shows that these differences arise very early in life."</p><p><strong>Along with the variations, there were some things that proved similar.<br></strong>Additionally, cells directed to develop as midbrain neurons (a brain region that's not implicated in autism dysfunction) showed only negligible differences between typical and autistic individuals. The similarities are just as important as the differences, as they mark how the autistic brain and typical brain develop uniquely from the earliest stages of growth.</p><p>"The use of iPSCs allows us to examine more precisely the differences in cell fates and gene pathways that occur in neural cells from autistic and typical individuals. These findings will hopefully contribute to our understanding of why there is such diversity in brain development," said Dr. Dr. Deepak Srivastava, who supervised the study.</p><p><strong>The intention of this study is not to find ways to "cure" autism, but to better understand the key genetic components that contribute to it.<br></strong>Simon Baron-Cohen, Ph.D., Director of the Autism Research Centre at Cambridge and the study's co-lead, added that "some people may be worried that basic research into differences in the autistic and typical brain prenatally may be intended to 'prevent,' 'eradicate,' or 'cure' autism. This is not our motivation, and we are outspoken in our values in standing up against eugenics and in valuing neurodiversity. Such studies will lead to a better understanding of brain development in both autistic and typical individuals."</p>
The sudden prevalence of an artery in the forearm is evidence that we're still very much a work in progress.
- Australian scientists see signs of accelerating human evolution.
- Exhibit A is the rapid rise in the prevalence of the median artery in adults.
- Other emerging traits, like shorter baby jaws, support their finding.
The rise of the median artery<p>The study was authored by scientists from <a href="https://www.flinders.edu.au" target="_blank">Flinders University</a> and the <a href="https://www.adelaide.edu.au/front/international.html?adobe_mc_sdid=SDID%3D6F3F7FE9AFD60DD6-7758ADFFE05FB639|MCORGID%3DBA023B045D5A83160A495E49%40AdobeOrg|TS%3D1602523779&adobe_mc_ref=https%3A%2F%2Fwww.google.com%2F" target="_blank">University of Adelaide</a> in South Australia. It's published in the <a href="https://onlinelibrary.wiley.com/doi/10.1111/joa.13224" target="_blank">Journal of Anatomy</a>.<br></p><p>The median artery supplies blood to a fetus' forearm in the womb during early gestation. It <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6327784/" target="_blank">typically</a> atrophies and is replaced by the radial and ulna arteries before birth. Few adults have historically had all three arteries — median, radial, and ulna — but this has been changing. </p><p>The study's senior author <a href="https://www.adelaide.edu.au/directory/maciej.henneberg" target="_blank">Maciej Henneberg</a> <a href="https://news.flinders.edu.au/blog/2020/10/08/forearm-artery-reveals-human-evolution-continues/" target="_blank">says</a>, "This is micro evolution in modern humans and the median artery is a perfect example of how we're still evolving because people born more recently have a higher prevalence of this artery when compared to humans from previous generations."</p><p>The phenomenon was first noticed in the 18th century, and a study of the artery's persistence was conducted in 1995. The more recent study extends that work, finding that the occurrence of the artery trio is accelerating.</p><p>"The prevalence was around 10% in people born in the mid-1880s compared to 30% in those born in the late 20th century," says lead author <a href="https://medicalsciences.med.unsw.edu.au/people/dr-teghan-lucas" target="_blank" rel="noopener noreferrer">Teghan Lucas</a>, "so that's a significant increase in a fairly short period of time, when it comes to evolution."</p><p>Why this is occurring isn't clear. "This increase could have resulted from mutations of genes involved in median artery development or health problems in mothers during pregnancy, or both actually," says Lucas.</p><p>However, she says, one thing is clear: "If this trend continues, a majority of people will have median artery of the forearm by 2100."</p><span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="1ad42f2dbdf44fb8ce1468e6bb53bab3"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/zIb9mymN80o?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
(Fore)armed with insight<p>The researchers tracked the presence the median artery in cadavers. They examined the 78 upper limbs obtained from Australians who died between 2015 and 2016. The deceased were from 51 to 101 years of age at death. In 26 of the limbs, the median artery was present.</p><p>Says Henneberg, "We've collected all the data published in anatomical literature and continued to dissect cadavers donated for studies in Adelaide, and we found about one third of Australians have the median artery in their forearm and everyone will have it by the end of the century if this process continues."</p><p>The scientists' conclusion is that we're evolving more quickly now than at any point in the last 250 years of study.</p>
Modern crops have been optimized for a lot of things, but not for climate change.
- Growers are struggling to protect their crops from failure as conditions change due to global warming.
- Modern crops lack the fortifying genetic diversity of their ancestors.
- Scientists publish a new guide for strengthening crops through the reintroduction of wild-variety traits based on the latest science.
The problem with domestication<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3NjU0Ny9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNzA2MDc2NX0.T41B0nuT0RnVyd_oFrmcCQMf6ZT6FpG2Gmrx9TCZ-mI/img.jpg?width=980" id="e86ad" class="rm-shortcode" data-rm-shortcode-id="19f58b1f2f0ba8c2295c824ff73514a5" data-rm-shortcode-name="rebelmouse-image" alt="plants" />
Credit: Markus Spiske/Unsplash<p>"When plants were domesticated," <a href="https://www.port.ac.uk/news-events-and-blogs/news/scientists-help-reboot-50-years-of-plant-advice" target="_blank">says</a> Dr. Perez-Barrales, one of the study's authors, "they were artificially selected for a specific desirable trait. Artificial selection and farming have led to quality improvements in foods such as meat, milk, and fruit. However, over hundreds of years, there has been a negative impact to this process — a reduction in plant genetic diversity."</p><p>This lack of diversity could spell doom for crops as the conditions in which they grow are impacted by climate change. Scientists believe that a plant's natural genetic makeup, which evolved in response to its surrounding conditions, makes it more likely to be able to continue to adapt. Domesticated crops may lack such flexibility.</p><p>According to Dr. Perez-Barrales, "Climate change is altering the way crops behave." Unfortunately, she adds, "Crops have lost so much genetic diversity they are less able to adapt and respond to climate change. Scientists are now looking at wild crop relatives to see what traits can be improved to make crops better adapted to the current environmental challenges."</p><p>This revisiting of crops' ancestors is very much on the mind of the new study's authors.</p>
A break from past practices<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQ3NjU2NS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMDIyMTEyOX0.vW6NyWC1Ey0uKeNKbBzcV99cyUEwECUpIwjOR-0Z09Q/img.jpg?width=980" id="e3743" class="rm-shortcode" data-rm-shortcode-id="70f3d0885d71401c00ba9329a6b480c5" data-rm-shortcode-name="rebelmouse-image" alt="farmer spraying fields" />
Credit: ittipon/Shutterstock/Big Think<p>The researchers began with a re-visiting of <a href="https://www.jstor.org/stable/1218252?seq=1" target="_blank">guidelines</a> published in 1971 to see how they might be modified. Says Perez-Barrales, "The classification developed in the early 1970s needed to be updated, and in effect rebooted, to integrate this modern information."</p><p>The study's lead author <a href="https://www.kew.org/science/our-science/people/juan-viruel" target="_blank">Juan Viruel</a> of Kew Garden explains, "With this information we can better select the wild species to improve our crops. It is an invaluable checklist for plant breeders and will help production of crops in a more sustainable way."</p><p>Those earlier guidelines also endorse the use of pesticides, now understood to harm fauna and leave fields toxic. The new study suggests a more benign, forward-looking way to deal with pests, says Perez-Barrales: "An alternative for plant breeders is to use wild crop relatives and use the natural genetic variation in those species that protects them against the natural enemies."</p>