Do Your Pearly Whites Shine Into Your Ancestor's Past?

Hooked For a Bite

Prior to last week, only one gene was confirmed to influence the structure of teeth in the human body. Today, we now know 18 genes well enough to pin what they influence in teeth, whether it be size or shape. This was achieved through the collection of data from almost 900 volunteers from Columbia who had dental plaster casts made of their teeth, which then got turned into 3D scans. Dental crown measurements were taken from this and the data was analyzed. It was found during the course of the studies that there was one gene believed to be carried over from Neanderthals. The Neanderthal gene variant linked to teeth was only found in people of European descent, and results in thinner incisors. This was done through comparison of SNPs, which was done based on the tooth phenotype displayed, as well as GWAS associations. I think this is a cool look into anthropology, and helps make progress in our understanding of the human genome, but I quite honestly see not value in this work beyond that and possibly coming up with new genome comparison and analysis methods.

Links

https://www.usnews.com/news/health-news/articles/2024-12-17/scientists-identify-genes-that-shape-peoples-teeth

https://www.cell.com/current-biology/fulltext/S0960-9822(24)01568-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982224015689%3Fshowall%3Dtrue

Find Out Why All Dentists are Having Trouble Falling Asleep

Teeth are well known to paleontologist for their prevalence and insight into the fossil record. Recently, geneticists are starting to starting to take notice as well.

Researchers at Trinity College Dublin have found two human teeth dating back some 4,000 years ago, and found that the microbiome of the mouth they came from was also remarkabley preserved. This allowed them to study the bacteria present and compare it to typical microbiomes of human oral cavities today. Not a huge surprise, but it was very different. The researchers were able to identify what bacteria was present from the perserved DNA profiles on the teeth.

The insights it gave them was that typical microbiomes in mouths 4,000 years ago may have been much more diverse than today. Although the teeth studied were over colonized by one bacteria S. mutans, demonstrating a pre-disease state, the fact that there was more biodiversity on the ancient teeth than our own is cause for concern. Like our guts, bacterial diversity is usually better and prevents overgrowth of disease causing strains. This pointed them to our changing diet, and the growing abundance of processed sugary foods some of us enjoy eating day to day. It is interesting to see Genetics having utility in archeology. Perhaps rock-lovers may soon be recruiting more DNA lovers for their specimen studies.

Posted by Michael Breslin

https://phys.org/news/2024-03-genetic-secrets-year-teeth-illuminate.html

https://www.sciencedaily.com/releases/2024/03/240327124735.htm

Genes are Key to Oral Health & Beyond

In a groundbreaking study encompassing over half a million participants, researchers embarked on a quest to unravel the intricate relationship between genetics and dental health. This study, published in Nature Communications and backed by data from sources like as the UK Biobank and the Gene-Lifestyle Interactions in Dental Endpoints consortium, supported by NIDCR, revealed 47 distinct genetic loci intricately linked to dental caries. Remarkably, among these findings were not only reaffirmations of previously known genetic influencers of dental health but also the discovery of novel genetic factors shaping oral well-being.Beyond its genetic revelations, the study uncovered compelling associations between dental health and a myriad of lifestyle factors, including smoking habits, educational attainment, and personality traits. Furthermore, intriguing connections emerged between oral health and systemic metrics such as cardiovascular and metabolic parameters, unveiling the profound interconnectedness between oral and overall health. I chose this article because among my generation, there has definitely been an uptick in individuals who receive veneers, which are fake teeth. Formerly used as replacement teeth, veneers are typically yellow to match existing teeth in a person's mouth. However, I noticed that a lot of the people nowadays with the veneers not only do an entire teeth replacement, but they end up choosing the straightest, whitest and overall most until set of teeth they could find. I always have wondered how bad their teeth could've been to drive them to make such a drastic change to their appearance. This article shows how so many genes come into play regarding how some peoples' teeth are. I liked this article because it highlights the reasons why someones teeth can become so damaged and how taking good care of your teeth and just your mouth in general can improve your quality of life. 

Sources

1. https://www.nidcr.nih.gov/news-events/nidcr-news/2019/genes-are-key-oral-health-beyond

2. https://www.queencreekcompletedental.com/blog/2021/08/20/can-bad-teeth-run-in-the-family/

Hypodontia of Maxillary Lateral Incisors

 Hypodontia, also known as tooth agenesis, is a frequent variation found in dental development and could occur as a part of a syndrome or in a nonsyndromic form. Genetic factors are a major component of the formation of these teeth in terms of size and shape. This particular study focuses on a specific variant of MSX1 (MSX1 rs8670). A sample of patients with isolated, maxillary, lateral incisor agenesis and matched controls had the measurements and morphology of their teeth noted. The methods of this analysis were: genotyping the MSX1 rs8670 genetic variant and morphometric measurements with a 2D image analysis. They were both performed for 26 hypodontia patients and 26 matched controls. This genotyping showed that the presence of the T allele increased the risk of upper lateral incisor agenesis to about 6.9 times the risk of individuals without the allele. There were also easily identifiable morphological differences between hypodontia patients and controls and between the unilateral and bilateral agenesis cases. Of all the teeth affected by hypodontia, the crown of the bucco-lingual dimension was the most affected. There was also evidence indicating that there was significant variation in the crown shape with the Carabelli trait of the upper first molars. The overall findings conclude that the MSX1 rs8670 variant does have associations with variations of the morphological outcomes in dentition. However, epigenetic and environmental factors interact with this variant to cause the variation in morphology, not just the variant itself.

The article highlights how genetics is intertwined with environmental factors, creating variation in morphology; in this case, specifically teeth. This demonstrates that a reliance on a singular factor for an outcome is not very common. Further linking of factors are needed to truly understand the observable traits in an individual, beyond just one or the other. I find the results of this analysis to be a beneficial supplement in studying similar variants in dentition in future analysis.

Link to the article “Genetic and Morphological Variation in Hypodontia of

Maxillary Lateral Incisors”: https://doi.org/10.3390%2Fgenes14010231

another related article: https://doi.org/10.1177/154405910808700715

Extinct Ancestor to Orangutan Opens up Doors for Further Human Evolution Research

Ancient protein sequencing has been used to determine the genetic position of the Gigantopithecus blacki. It revealed that the orangutan is its closest living relative. This is the first time that genetic information this old has been able to be used from such a warm, damp environment. This is important because primates are closely related to humans, meaning it may be possible to retrieve similar information on the evolutionary line leading to humans. We used to only be able to go back about 400,000 years, but now it may be possible to trace human evolution as far back as two million years. The sequencing of proteins from dental enamel also proved to be useful when studying lineage of species, when there is no surviving DNA. Only a few jaws, but a lot of teeth were found from this species. This protein sequencing of the enamal showed that the orangutan and Gigantopithecus blacki split up about 12 million years ago. Mass spectrometry was used to analyze these protein sequences. Because there are not a lot of fossils found from Gigantopithecus blacki, a lot of speculation surrounds what its physical characteristics may have been.

A lot is already known about the evolution of a lot of animals and of humans, but there is still so much missing. When new fossils are found and they are sequenced to find out which species they are closest related to, a whole new door is opened. From there other lineages can be mapped out and we can get a clearer understanding of how evolution occurred. What's even more interesting about this case, is that the way these fossils were sequenced opened up new possibilities for the sequencing of future fossils from extinct human species. Now more questions about the evolution of humans can be answered.

Link:
https://www.sciencedaily.com/releases/2019/11/191113153053.htm

Related Article:
https://healthsciences.ku.dk/newsfaculty-news/2019/11/extinct-giant-ape-directly-linked-to-the-living-orangutan/

The Gumboot Chiton's Magnetic Teeth May Be Key for Nanoscale Technology

The gumboot chiton (Cryptochiton stelleri), a species of mollusks found along the shores of California, have teeth made from magnetite. Magnetite is a magnetic material made of iron found on Earth's crust, but only a few animals are able to produce it. Gumboot chitons scrape algae off ocean rocks using their magnetic teeth, but not much is known of the biomechanisms behind the production of their teeth. Chitons have dozens of rows teeth with each cusp made of magnetite, but after scraping rock for long periods of time, the teeth begin to wear which are then replaced by new teeth.
A gumboot chiton (left), also known as the "wandering meatloaf", with its teeth (right).


A research team lead by Michiko Nemoto of Okayama University and David Kisailus of UC Riverside recently discovered how the mollusk is able to produce magnetite teeth. While researchers would usually look toward specific genes in their genome, the research team actually examined the chiton's transcriptome, the set of all mRNA molecules expressed from the genes. In the developing teeth region of the RNA transcripts, they found ferritin, an iron-storing protein. In the mineralized teeth region, they found a large amount of mitochondria that provide the energy needed to transform the molecules into magnetite. A new protein was even discovered which they identified as radular teeth matrix protein1.

I stumbled upon these unique creatures when I was looking for genetic articles on teeth. My interest in dentistry brought me here, but it was exciting to read about these new discoveries and how they are being brought into the light of engineering. Next-generation electronics require nanoscale energy, and by studying gumboot chitons, researchers are closer to developing nanaoscale energy sources since knowing how to control biological magnetite is essential to the process. I was also fascinated by the fact that the research team looked into the transcriptome instead of the genome. Some of my past blog posts looked into researchers who would study specific genes in the genome to find what they were looking for, but the research team in this article examined the transcriptome because they thought it would be easier to look at the regions that are actually expressed.

Links to Sources:
https://news.ucr.edu/articles/2019/01/31/magnetic-teeth-hold-promise-materials-and-energy
https://www.nature.com/articles/s41598-018-37839-2

Genetics behind defects of Canine Enamel

A study from the University of Helinski determined that humans and dogs share the same two genes that may be the cause of their enamel issues. Two genes, ENAM and ACP4, were previously linked in humans for their cause in enamel disorders were also found in multiple types of dogs. The disorder, Amelogenisis imperfect (AI), is what is known in humans to cause the hereditary disorders of the enamel. This disorder is linked with 10 genes including ACP4 and ENAM. The disorder can cause physical and dental harm to both dogs and humans. Mutations or defects in these two genes can cause  developmental issues in the thickness of the enamel, quality or even absence of it entirely. The ENAM mutation controls the protein, Enamelin, which controls whether the teeth receive the correct amount of thickness of enamel. The ACP4 mutation is controlled by the phosphatase enzyme which we think controls cellular differentiation and mineralisation however this data is not fully clear yet.

Dogs with the ACP4 mutation did show thin enamel and a slight mineralisation disorder. 

Due to dogs having the same primary and permanent types of teeth and similar numbers of teeth I think this is a very useful study to conduct. Previously, most of these cases remained undiagnosed but now we have a chance to learn more about the causes of these mutations and exactly what they control. This is both great for the human as well as there best friend, the dog for there overall health.

The first sequencing of "Streptococcus sobrinus"

A team of  Illinois Bioengineering researchers from the University of Illinois, led by, Assistant Professor Paul Jensen, sequenced the genome of three different strains of Streptococcus sobrinus. This bacteria is of the coccus (plural cocci) that have a spherically round shape. They can be found in different configurations. Alone as one coccus, diplococci as a pair. streptococci as a chain, staphylococci in a pyramid like structure, and so on. Streptococcus sobrinus is in a chain structure (as seen in figure 1), this bacteria is known for accelerated tooth decay in certain individuals. The S. mutans forms tartar on the teeth and uses the sugars we eat and creates it into acid, which becomes to strong for out teeth and then decalcifies it. 
S. sobrinus is a rare bacteria, as it is not present in all humans, and has been difficult for Jensen to work with. With working with the S. mutan strains they were able to get to the elusive S. sobrinus. Jensen states "Although it is rare, S. sobrinus produces acid more quicklu and is associated with the poorest clinical outcomes, especially among children, if S. sobrinus is present along with S. mutans, you're at risk for rampant tooth decay, which means there's some level of communication or synergy between the two that we don't understand yet."
This squencing has paved the road to a better understanding of the interactions between these two strains and how they create a devastating combo. What is known so far from Jensen is that " S. mutans bacteria sends out feelers in the form of a peptide to find out how many other S. mutans cells are nearby." the moment that there are enough they go on the offensive and begin to harm a persons mouth. This creates an imbalance of "good' bacteria to "bad" bacteria.

Reference:
1 -  https://bioengineering.illinois.edu/news/article/27184
2- https://mra.asm.org/content/7/3/e00804-18

'Jaws' May Help Humans Grow New Teeth, Shark Study Suggests

A study has been done to help identify the network of genes that allows sharks to develop and regenerate their teeth throughout their lifetime. The genes allow the sharks to replace rows of their teeth using what they call "a conveyer belt-like system". Scientists have known for awhile that some fish have the ability to do this but didn't exactly understand how it happened. But a research team from the University of Sheffield's Department of Animal and Plant Sciences, led by Dr. Gareth Fraser have pin-pointed out a special set of epithelial cells form called, dental lamina. The dental lamina is responsible for the regeneration of tooth development in the sharks throughout their lifetime. 

Humans have a set of cells which causes the reproduction of replacement teeth, but only two sets are formed, baby teeth and your adult teeth. Dr. Fraser actually stated that although sharks are seen to be fearsome creatures, but one of the main reasons that they are successful predators is because of their sharp teeth that regenerate quickly and are replaced before they are able to decay.

I think this is actually a really great finding which if it became fully developed could really help a lot of people. I know that some teeth decay and fall out but if this were to continue, people could regularly replace those fallen out teeth if that were to happen. It would definitely have to be tested and thought out properly before it goes through. I can see how this research can be bad in some ways for dentists. I know that I am hoping to go to dental school after college and you have to learn about how to implant new teeth if one were to fall out, so that would take money away from the dentistry world. 

Will We Never Have To Worry About Losing Teeth Again?

A study from the University of Sheffield has identified a set of genes responsible for the continuous replacement of teeth seen in sharks.  These genes are responsible for the formation and operation of special cells called the dental lamina that from new teeth - the same cells that form baby teeth and adult teeth in humans.  Because the study showed that these genes have been conserved over hundreds of millions of years, they predict that these same genes made the first vertebrate teeth, and are also responsible for the production of human teeth.

A catshark

The study, which analyzed the teeth of catshark embryos, also found that these genes were activated when the shark's teeth first form, when they emerge, and when the shark needs new teeth.  They hope that the discovery of these genes will lead to new treatments for tooth loss in humans.
What it sounds like to me is that they hope to find a way to reactivate these genes so that lost teeth can be replaced.  If they can figure out how to do this, it would put a lot of dentists out of work, because who cares about toothcare when bad teeth can be automatically replaced?  Seriously though, that probably wouldn't happen, because the treatment would probably be really expensive, at least at first, and in all likelihood would need to be reapplied for every tooth lost.  Still, the idea of regaining good, strong, real teeth when some are lost is appealing.  Though denture-making companies will lose some business.

Can teeth really show us evidence of plague?

Eske Willerslev and his colleagues, at the University of Copenhagen, in Denmark, began studying DNA from bacteria on teeth that caused plague during the Bronze Age and Iron Age. This time was marked between 4,800 and 3,000 years ago. Willerslev concluded the early plague germ, Yersinia pestis, was spread from person to person among the herders migrating across Europe and Asia during the Bronze Age. Coughing could have spread the plague, and if the germ caused a lung infection, the illness was considered pneumonic plague. If the blood of an individual became infected, it was considered septicemic plague.

            Willerslev and his team identified Y. pestis DNA on teeth from Bronze and Iron Age individuals. The DNA pieces showed up in seven of the 101 people. Two people with the strain were from Russia roughly 4,800 years ago. Another was from North Central Europe, 4,500 years ago. The third infected person examined was in West Asia from almost 4,200 years ago. Several more teeth collected were from Siberia and Poland and were 3,700 to 4,000 years old. The last sample was from an individual who lived in Armenia 3,000 years ago.

            From the evidence Willerslev and his team gathered, it is clear the germ spread over a wide area and for a large amount of time. Further investigation was concluded of the entire genome in the Bronze Age DNA. The analysis showed the earlier germ lacked the gene, which was present in the Iron Age individual. This gene allowed bacterium to survive in a flea’s gut. The plague germ would have been able to spread via flea bites at some point during 3,700 and 3,000 years ago.

            The biologists have compared plague DNA in one of the oldest Bronze Age individuals and the most recent Bronze Age individual and concluded both lacked a form of one plague gene that keeps an infected persons immune system from attacking the disease. This suggests that the earlier forms of the germ would have been vulnerable to attacks by the immune system. 

            One reason I found this article to be interesting was due to the time periods Willerslev and his team worked with. They collected and screened 89 billion pieces of DNA from teeth of individuals from the Bronze and Iron Age. That was almost 5,000 years ago! It is fascinating to know a scientist can pull ancient DNA from teeth of individuals that lived thousands of years ago. Another captivating point in the article mentioned this disease took over even when there really was no urbanization. But certainly this plague evolved and survived longer than expected. 

Dino-Chicken--Not of the Nugget Variety

With the recent Jurassic World movie, even this generation's young people know about the disastrous outcome of when scientists "play god" and create a park full of dinosaurs. Despite this, dinosaur breeding may be closer than one may think. The Indominous rex was one of the unlikely stars of the recent Jurrasic World movie, for a good reason. While fossilized dinosaur DNA that is still viable has yet to be found, remnants of the prehistoric code that existed in dinosaurs still exists in chickens today. Quoted in an article on livescience, James Horner, the inspiration for the original Jurassic Park's Alan Grant, says, "Chickens and all birds are carrying much bigger chunks of dinosaur DNA than we are ever likely to find in the fossil record." He believes that, because DNA tends to come apart after a cell dies, there wouldn't be anything left after millions of years.
However, in a bird, there may be enough groundwork and prehistoric DNA that they could be essentially reverted to resemble a dinosaur. It's already been proven that birds can be transgenically created to have teeth and a team from Yale and Harvard recently retro-engineered a bird's beak to look like a dinosaur-looking mouth. Horner believes that all that is left is to recreate the tails and transform the wings back into an arm and hand. He admits a miniature dinosaur may be about ten years off.
While this is scary, much like Grant I would love my own miniature pet dinosaur, but I do believe this whole exercise would anger people who are traditionally against GMOs. This involved completely modifying an organism to create something completely different which leaves a weird taste in my mouth.