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Are there no beneficial mutations?

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  • #76
    Source: https://www.sciencealert.com/researchers-have-found-a-brand-new-way-that-squid-can-edit-rna



    Squids Can Edit Their RNA in an Unprecedented Way, Scientists Discover

    When it comes to squids, you just can't keep them down.

    Not just because they're slippery, but also because they have an incredible genetic editing ability - it lets them tweak their own RNA long after it's left the nucleus.


    Here's what that means. Genes, in humans at least, mostly stay unchanging until they're recombined and passed onto the next generation.

    This is the same for our messenger RNA (mRNA). Helpful molecules read our DNA, create short little RNA messages, and send them outside the nucleus to tell the rest of the cell which proteins need to be built.

    Once that mRNA has exited the nucleus, it's thought the genetic information it carries can't be messed with much - but new research has shown that in squid nerves, this isn't the case.

    "We are showing that squid can modify the RNAs out in the periphery of the cell," says Marine Biological Laboratory (MBL), Woods Hole geneticist Joshua Rosenthal.

    "It works by this massive tweaking of its nervous system," Rosenthal told Wired. "Which is a really novel way of going through life."

    The team took nerves from specimens of adult male longfin inshore squid (Doryteuthis pealeii), and analysed the protein expression, as well as the squids' transcriptome, which is similar to a genome, but for mRNA.


    They found that in squid nerves (or neurons), the mRNA was being edited outside of the nucleus, in a part of the cell called the axon.

    This mRNA editing allows the squids to finely tune the proteins they produce at local sites (see diagram below). With this finding, squids have become the only creatures we know of that can do this.

    Squid RNA Editing Graphical Abstract ver. 3
    (Vallecillo-Viejo et al., Nucleic Acids Research, 2020)

    This isn't the first time squids have shown off their genetic editing prowess, though. Back in 2015, a similar team at MBL discovered that squids edit their mRNA inside their nucleus to an incredibly large degree – orders of magnitude more than what happens in humans.

    "We thought all the RNA editing happened in the nucleus, and then the modified messenger RNAs are exported out to the cell," Rosenthal explains.

    But the team showed that although editing is happening in both, it occurs significantly more outside the nucleus in the axon, rather than inside the nucleus.

    So, why do squids bother? Why do they need to change their mRNA so much? Well, we don't yet know, but the research team has some ideas.


    Octopus, cuttlefish and squids all use mRNA editing to diversify the proteins produced in the nervous system. This could be one of the reasons why these creatures are so much smarter than other invertebrates.

    "The idea that genetic information can be differentially edited within a cell is novel and extends our ideas about how a single blueprint of genetic information can give rise to spatial complexity," the team writes in their new paper.

    "Such a process could fine-tune protein function to help meet the specific physiological demands of different cellular regions."

    Although right now this is just an interesting genetics study into squids, the researchers think that eventually, this type of system might be able to help treat neurological disorders that include axon dysfunction.

    CRISPR has completely changed the game when it comes to editing the DNA inside our cells, and RNA is significantly less permanent and therefore editing it could be less dangerous.

    "RNA editing is a hell of a lot safer than DNA editing," Rosenthal told Wired.

    "If you make a mistake, the RNA just turns over and goes away."

    The research has been published in Nucleic Acids Research.

    © Copyright Original Source

    Glendower: I can call spirits from the vasty deep.
    Hotspur: Why, so can I, or so can any man;
    But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

    go with the flow the river knows . . .

    Frank

    I do not know, therefore everything is in pencil.

    Comment


    • #77
      Another example of a mutation that is beneficial, possibly even essential for our survival, later leading to problems.


      Source: Humans Might Be So Sickly Because We Evolved to Avoid a Single Devastating Disease


      Hundreds of thousands of years ago, our ancestors evolved a simple trick that could have helped thwart a major infectious disease. It probably saved our skins, but the change was far from a perfect solution.

      New research has uncovered evidence that mutations arising between 600,000 and 2 million years ago were part of a complex of adaptations that may have inadvertently made us prone to inflammatory diseases and even other pathogens.

      An international team of researchers compared around a thousand human genomes with a few from our extinct cousins, the Neanderthals and Denisovans, to fill in missing details on the evolution of a family of chemicals that coat the human body's cells.

      Sialic acids are a diverse group of carbohydrates that blossom like leaves from the tips of proteins covering the surfaces of human cells.

      This canopy of sugars is typically the first thing you'd bump into if you were the size of a virus or bacterium, so it's no surprise that these chemicals serve as a security badge, identifying friend from foe.

      Changes in sialic acid markers can give rise to a number of diseases. But it was one specific change particular to all humans that the researchers here were most keen to gain an understanding of.

      Most mammals – including closely related apes – have a compound called N-glycolylneuraminic acid, or Neu5Gc. We've known for some time that the gene for this version of sialic acid is broken in us, leaving its precursor form, N-acetylneuraminic acid (Neu5Ac), to do its job.

      Researchers previously speculated that this mutation was selected for in humans to make it harder for devastating malarial parasites such as Plasmodium knowlesi to latch onto red blood cells.

      It's a swap that other animals – including a number of birds, bats, and even whales – have also evolved on their own.

      Since chimpanzees retain the gene for Neu5Gc, the mutation must have occurred within the past 6 million years or so, sometime after we parted ways from one another.

      This window can now be narrowed down even further. This most recent study shows Neanderthals and Denisovans share our variant of sialic acid, meaning the change happened before our branch of the family tree separated roughly 400,000 to 800,000 years ago.

      Sialic acid markers are only part of the story, though. To differentiate between cells that belong to us from possible invaders, our immune cells are armed with a scanning chemical called sialic acid-binding immunoglobulin-type lectins. Or Siglecs for short.

      When an inspection occurs, if a cell's sialic acid marker isn't up to scratch, it's curtains for that cell. Naturally, any changes to our sialic acid name-tag would imply our system of Siglecs would have needed adjusting as well.

      Sure enough, on further investigation the researchers found significant mutations among a cluster of Siglec genes that are common to humans and their ilk, but not great apes.

      Not all of these versions are found on immune cells, either. According to the study, some are found on other tissues, such as the brain, placenta, and gut.

      This radical rewiring of our immune system is no small thing. If the malaria-hypothesis carries weight, it would have given Neu5Ac humans living in areas prone to the parasitic disease a huge advantage over their Neu5Gc relatives.

      But it might have been a big price to pay. A decade ago, researchers from the same team suggested the mutation would have separated our ancestral communities, potentially preventing them from reproducing.

      In other words, our species' lineage might have splintered as a result of this complex of immune mutations, possibly occurring with the emergence of Homo erectus a little more than 2 million years ago.

      But there are other consequences of the change we're still experiencing today.

      Siglec expression is linked with conditions such as asthma and Alzheimer's disease, raising the possibility that protection from a devastating disease put us at risk of other conditions.

      As for that swap in sialic acid, it might have provided a new opportunity for a slew of other pathogens.

      A wide variety of viruses and bacteria gain entry to our cells by grabbing onto the fuzz of sialic acid, many of which infect humans but not apes. Many, such as cholera, smallpox, influenza, and coronaviruses, are far from trivial.

      "Most coronaviruses infect cells in two steps – first by recognising abundant sialic acids as binding sites to gain a foothold, and then seeking out the higher affinity protein receptors like ACE2," physician Ajit Varki told Science magazine's Ann Gibbons.

      Strangely, a human-like elimination of the NeuA5c gene in mice gives them a boost in running ability, and in activating other parts of their immune system. Given the new cognitive and physical talents emerging in humans a couple of million years ago, asthma and cholera might well have been worth the swap.

      Evolution gets the job done. But nobody said it was perfect.



      Source

      © Copyright Original Source



      "Evolution gets the job done. But nobody said it was perfect." I can't remember who coined the description of biology being "gloriously messy" but that is exactly what it is -- especially when you are limited to modifying and adapting existent material.

      In any case, the entire paper, "Multiple Genomic Events Altering Hominin SIGLEC Biology and Innate Immunity Predated the Common Ancestor of Humans and Archaic Hominins" can be read HERE. This is the abstract from it:

      Human-specific pseudogenization of the CMAH gene eliminated the mammalian sialic acid (Sia) Neu5Gc (generating an excess of its precursor Neu5Ac), thus changing ubiquitous cell surface “self-associated molecular patterns” that modulate innate immunity via engagement of CD33-related-Siglec receptors. The Alu-fusion-mediated loss-of-function of CMAH fixed ∼2–3 Ma, possibly contributing to the origins of the genus Homo. The mutation likely altered human self-associated molecular patterns, triggering multiple events, including emergence of human-adapted pathogens with strong preference for Neu5Ac recognition and/or presenting Neu5Ac-containing molecular mimics of human glycans, which can suppress immune responses via CD33-related-Siglec engagement. Human-specific alterations reported in some gene-encoding Sia-sensing proteins suggested a “hotspot” in hominin evolution. The availability of more hominid genomes including those of two extinct hominins now allows full reanalysis and evolutionary timing. Functional changes occur in 8/13 members of the human genomic cluster encoding CD33-related Siglecs, all predating the human common ancestor. Comparisons with great ape genomes indicate that these changes are unique to hominins. We found no evidence for strong selection after the Human–Neanderthal/Denisovan common ancestor, and these extinct hominin genomes include almost all major changes found in humans, indicating that these changes in hominin sialobiology predate the Neanderthal–human divergence ∼0.6 Ma. Multiple changes in this genomic cluster may also explain human-specific expression of CD33rSiglecs in unexpected locations such as amnion, placental trophoblast, pancreatic islets, ovarian fibroblasts, microglia, Natural Killer(NK) cells, and epithelia. Taken together, our data suggest that innate immune interactions with pathogens markedly altered hominin Siglec biology between 0.6 and 2 Ma, potentially affecting human evolution.

      I'm always still in trouble again

      "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
      "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
      "Of course, human life begins at fertilization that’s not the argument." --Tassman

      Comment


      • #78
        Originally posted by lee_merrill View Post
        Not if you can argue that degradative mutations predominate in selection.


        No, Behe doesn't call any modification "degrading". He says that most variations that increase fitness are degradative.

        Blessings,
        Lee
        Well, ah . . . your loaded question is trappy and misleading, The following may be helpful if you read the whole reference, which I dought you will.

        Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871823/



        The population genetics of mutations: good, bad and indifferent
        Laurence Loewe1,2,* and William G. Hill1

        ABSTRACT
        Population genetics is fundamental to our understanding of evolution, and mutations are essential raw materials for evolution. In this introduction to more detailed papers that follow, we aim to provide an oversight of the field. We review current knowledge on mutation rates and their harmful and beneficial effects on fitness and then consider theories that predict the fate of individual mutations or the consequences of mutation accumulation for quantitative traits. Many advances in the past built on models that treat the evolution of mutations at each DNA site independently, neglecting linkage of sites on chromosomes and interactions of effects between sites (epistasis). We review work that addresses these limitations, to predict how mutations interfere with each other. An understanding of the population genetics of mutations of individual loci and of traits affected by many loci helps in addressing many fundamental and applied questions: for example, how do organisms adapt to changing environments, how did sex evolve, which DNA sequences are medically important, why do we age, which genetic processes can generate new species or drive endangered species to extinction, and how should policy on levels of potentially harmful mutagens introduced into the environment by humans be determined?

        Keywords: deleterious and advantageous mutations, distribution of mutational effects, linkage, background selection, Muller's ratchet, evolution
        Go to:

        1. INTRODUCTION
        Mutations are one of the fundamental forces of evolution because they fuel the variability in populations and thus enable evolutionary change. Based on their effects on fitness, mutations can be divided into three broad categories: the ‘good’ or advantageous that increase fitness, the ‘bad’ or deleterious that decrease it and the ‘indifferent’ or neutral that are not affected by selection because their effects are too small. While this simplistic view serves well as a first rule of thumb for understanding the fate of mutations, research in recent decades has uncovered a complex web of interactions. For example, (i) the effects of mutations often depend on the presence or absence of other mutations, (ii) their effects can also depend on the environment, (iii) the fate of mutations may depend on the size and structure of the population, which can severely limit the ability of selection to discriminate among the three types (making all seem nearly ‘indifferent’), and (iv) mutations' fate can also depend on the fate of others that have more pronounced effects and are in close proximity on the same chromosome.

        A major theoretical goal in the study of the population genetics of mutations is to understand how mutations change populations in the long term. To this end, we have to consider many features of evolution and extant populations at both the phenotypic and molecular level, and ask how these can be explained in terms of rates and kinds of mutations and how they are affected by the forces that influence their fates.

        We have increasing amounts of information at our disposal to help us answer these questions. The continuous improvement of DNA sequencing technology is providing more detailed genotypes on more species and observations of more phenomena at the genomic level. We are also gaining more understanding of the processes that lead from changes at the level of genotypes through various intermediate molecular changes in individuals to new visible phenotypes. Use of this new knowledge presents both opportunities and challenges to our understanding, and new methods have been developed to address them.

        Brian Charlesworth has been at the forefront of many of the developments in the population genetics of mutations, both in the collection and analysis of new data and in providing new models to explain the observations he and others have made. This themed issue of Phil. Trans. R. Soc. B is dedicated to him to mark his 65th birthday. The authors of the accompanying papers have individually made important contributions to the field and have been directly associated with or indirectly influenced by his work.

        In this collection of papers, various aspects are considered in detail, and in this introduction, we aim to provide an overview as a basis for the in-depth treatments that follow. We outline some of the theories that serve as the quantitative basis for more applied questions and have been developed with the main aims of: (i) measuring the rates at which different types of mutations occur in nature, (ii) predicting quantitatively their subsequent fate in populations, and (iii) assessing how they affect some properties of populations and therefore could be used for inference. The subsequent papers are broadly arranged in a continuum from specific questions of basic parameter estimation (strength of mutation, selection, recombination), via those that contribute a combination of biological theories and data on these parameters, to those which mostly address broader biological theories.

        There is an enormous range of mutational effects on fitness, and wide differences exist in the strength of other evolutionary forces that operate on populations. This generates an array of complex phenomena that continues to challenge our capacity to mechanistically understand evolution. To make problems tractable, theoreticians have divided the parameter space into smaller regions such that specific simplifying assumptions can be made. These typically comprise assuming the absence of particular events (e.g. no recombination) or the presence of particular equilibria (e.g. mutation-selection balance). Subsequently, new theories are often developed in which these assumptions are relaxed so as to narrow the gap to reality, typically including more interactions between various evolutionary forces, albeit at the cost of becoming less tractable to analysis.

        © Copyright Original Source

        Glendower: I can call spirits from the vasty deep.
        Hotspur: Why, so can I, or so can any man;
        But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

        go with the flow the river knows . . .

        Frank

        I do not know, therefore everything is in pencil.

        Comment


        • #79
          Originally posted by lee_merrill View Post
          But I need specific references!

          Blessings,
          Lee
          Need reputable peer reviewed references, and not Behe with a religous agenda.
          Glendower: I can call spirits from the vasty deep.
          Hotspur: Why, so can I, or so can any man;
          But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

          go with the flow the river knows . . .

          Frank

          I do not know, therefore everything is in pencil.

          Comment


          • #80
            Originally posted by rogue06 View Post
            I was switching through the channels this morning and as I came to one of the local religious channels I noticed that the host of the show was talking to a man wearing a lab coat. Since folks don't generally go around wearing lab coats it caught my interest so I stopped to see what was going on.




            15. And the one that gets evolution deniers all worked up are the various mutations that confer resistance to malaria. Nearly everyone is aware of the sickle cell allele which confers resistance to malarial infections if you carry one copy of the allele but causes sickle cell anemia if you carry two copies. It's a good example of balancing selection. And even those with sickle cell anemia are considerably more likely to survive long enough to reproduce than those suffering from malaria.

            What many are not aware of is that there are other alleles which confer resistance. The HbC variant for hemoglobin confers a 29% reduction in risk for malarial infection if you have one copy but a 93% risk reduction if you have two copies. The anemia resulting from the double copy of this gene variant is very mild in contrast to the debilitating effects of sickle cell.

            Then there is the various types of Thalassemia. While they all have negative effects (bone deformities, and cardiovascular illness like anemia) it also confers a degree of protection against malaria (specifically, malaria caused by the protozoan parasite Plasmodium falciparum) and those with β-thalassemia apparently have some protection against coronary heart disease.

            Finally, a single genetic mutation protects some African children from the deadly symptoms of malaria. The mutation occurs in the gene NOS2 that encodes an enzyme to produce the gas nitric oxide -- something that is present throughout the human body. The mutation is a polymorphism, a single letter change in DNA. It causes cells to ramp up production of the gas, which is thought to protect people against malaria.

            Children in Tanzania and Kenya who have the mutation are much less likely to develop the disease than children who do not, with one study discovering that those with the mutation living in Tanzania were nearly 90% less likely to develop severe malaria than individuals without the mutation.
            Researchers have discovered something similar among DNA variants that allowed our ancestors to survive the Black Death (which reduced the world's population from roughly 475 million down to 350 to 375 million and retuned periodically to kill millions more over the centuries) are linked to several diseases today.


            Source: Autoimmune diseases tied to genes of Black Death survivors, study says


            The Black Death, the 14th-century bubonic plague that killed some 1 in 3 people in Europe and an estimated 200 million across the world, has left another long-lasting mark: on the immune systems of people living today.

            Four DNA variants appear to have helped boost survival rates from the plague — caused by a bacterium, “Yersinia pestis,” carried by small mammals and their fleas — in the mid-1300s and in recurring bouts of plague in later centuries, according to a recent study published in the journal Nature.

            Researchers from the University of Chicago, McMaster University in Ontario and the Pasteur Institute in Paris say at least two of those variants associated with surviving the Black Death can be linked to autoimmune conditions common in modern society — including Crohn’s disease and rheumatoid arthritis.

            Hendrik Poinar, a professor of anthropology at McMaster University and senior co-author on the study, said in the release that the research offered insight into “how pandemics can modify our genomes but go undetected in modern populations.”

            Poinar noted that while the genes “provided tremendous protection during hundreds of years of plague epidemics,” they are linked to autoimmune disorders. “A hyperactive immune system may have been great in the past but in the environment today it might not be as helpful,” he said.

            Having “two copies of a specific variant of one gene in particular, ERAP2, was strongly associated with surviving the plague,” according to a video published by the University of Chicago to explain the findings. People who survived the Black Death eventually passed the genetic variant to their children. Individuals who inherited such mutations were about 40 percent more likely to survive the plague, the research found.

            Luis Barreiro, a professor of genetic medicine at the University of Chicago, said in a release on the study that the group’s findings served as “evidence that this one single disease event was enough to lead to selection in the human immune system.”

            Barreiro said the findings were one of a kind. “This is, to my knowledge, the first demonstration that indeed, the Black Death was an important selective pressure to the evolution of the human immune system,” he said.

            The medieval plague remains a topic of fascination among researchers and historians due to its “extensive demographic impact and long-lasting consequences,” the study notes, some 700 years after the deadliest pandemic recorded in history.

            Researchers involved in the study analyzed high-quality genetic variation in more than 200 DNA samples extracted from the bones or teeth of individuals from Denmark and London who lived before the plague, died of it or lived between one and two generations after it swept the world.

            There are different clinical forms of plague, though the most common are bubonic, pneumonic and septicemic, according to the Centers for Disease Control and Prevention. The Black Death, also referred to as the Pestilence, was a bubonic plague pandemic. Symptoms included skin tissue darkened by gangrene and swelling of lymph nodes, or buboes — the source of the term “bubonic.”

            The plague strain eventually evolved into a less-dangerous variety, and today the protective variant is present in about 45 percent of British people, according to the 1000 Genomes database, Science Magazine reported in a write-up of the study. Deadly plague outbreaks remain a threat in some areas, but prevention and treatment methods have improved drastically, especially through the use of antibiotics.

            The findings have raised the question: Will the coronavirus pandemic have a big impact on human evolution?

            Fortune magazine reported that Barreiro is not convinced. The Black Death was far deadlier, he said, killing on scale orders of magnitude beyond the effects of covid-19, and had a more devastating effect on the young, killing people before they could pass on their genes.



            Source

            © Copyright Original Source



            The entire paper, Evolution of immune genes is associated with the Black Death can be read by clicking the link while the abstract is also available below


            Abstract

            Infectious diseases are among the strongest selective pressures driving human evolution1,2. This includes the single greatest mortality event in recorded history, the first outbreak of the second pandemic of plague, commonly called the Black Death, which was caused by the bacterium Yersinia pestis3. This pandemic devastated Afro-Eurasia, killing up to 30–50% of the population4. To identify loci that may have been under selection during the Black Death, we characterized genetic variation around immune-related genes from 206 ancient DNA extracts, stemming from two different European populations before, during and after the Black Death. Immune loci are strongly enriched for highly differentiated sites relative to a set of non-immune loci, suggesting positive selection. We identify 245 variants that are highly differentiated within the London dataset, four of which were replicated in an independent cohort from Denmark, and represent the strongest candidates for positive selection. The selected allele for one of these variants, rs2549794, is associated with the production of a full-length (versus truncated) ERAP2 transcript, variation in cytokine response to Y. pestis and increased ability to control intracellular Y. pestis in macrophages. Finally, we show that protective variants overlap with alleles that are today associated with increased susceptibility to autoimmune diseases, providing empirical evidence for the role played by past pandemics in shaping present-day susceptibility to disease.



            Last edited by rogue06; 11-03-2022, 07:29 AM.

            I'm always still in trouble again

            "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
            "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
            "Of course, human life begins at fertilization that’s not the argument." --Tassman

            Comment


            • #81
              Are you aware of the beneficial mutation observed during an experiment being run by the Discovery Institute?
              Last edited by Roy; 11-03-2022, 08:29 AM.
              Jorge: Functional Complex Information is INFORMATION that is complex and functional.

              Mountain Man: First of all, the Bible is a fixed document.
              Mountain Man on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
              Mountain Man on climate change: Looking at the historical temperature data in my region over the past ten years shows that temperatures have been stable ...

              Comment


              • #82
                I probably should include this one as well, which I posted about in 2017


                Originally posted by rogue06 View Post
                It appears that the people who live in the Quebrada Camarones region of Chiles Atacama desert have evolved a mutation that allows them to drink the water with high levels of arsenic (over 100 times the World Health Organizations safe limit) in it without ill effect.

                Source: Human adaptation to arsenic in Andean populations of the Atacama Desert


                Abstract

                Objectives
                Quebrada Camarones, in the Atacama Desert, has the highest arsenic levels in the Americas (>1,000 µg/L). However, the Camarones people have subsisted in this adverse environment during the last 7,000 years and have not presented any epidemiological emergencies. Therefore, to solve this conundrum we compared the frequencies of four protective genetic variants of the AS3MT gene associated with efficient arsenic metabolization, between the living populations of Camarones and two other populations historically exposed to lower levels of arsenic.


                Materials and Methods
                The Chilean selected population samples come from Quebrada Camarones (n = 50) and the Azapa Valley (n = 47) in the north and San Juan de la Costa (n = 45) in southern Chile. The genotyping was conducted using PCR-RFLP. We compared the genotypic and allelic frequencies, and estimated the haplotype frequencies in the AS3MT gene.


                Results
                We found higher frequencies of the protective variants in those people from Camarones than in the other two populations. The haplotype estimation showed that the combination of protective variants of CTTA is very frequent in Camarones (68%) and Azapa (48%), but extremely low in San Juan de la Costa (8%). Also, the C variant associated with toxicity risks in the SNP Met287Thr had a lower frequency in Camarones (1%) and is higher in the other populations.

                Discussion
                The higher frequency of protective variants in both northern Chilean populations indicates a long exposure to naturally arsenic-contaminated water sources. Our data suggest that a high arsenic metabolization capacity has been selected as an adaptive mechanism in these populations in order to survive in an arsenic-laden environment.



                Source

                © Copyright Original Source



                As an article in New Scientist explains:

                The body uses an enzyme called AS3MT to incorporate arsenic in two compounds, monomethylarsonic (MMA) acid and dimethylarsinic (DMA) acid. People who metabolise arsenic more efficiently convert more of it into the less toxic, more easily expelled DMA.

                Mario Apata of the University of Chile in Santiago and his colleagues looked at variations in the gene coding for AS3MT in nearly 150 people from three regions of the country. They found higher frequencies of the protective variants in people from Camarones: 68 per cent there had them, as opposed to just 48 and 8 per cent of people in the other two. Our data suggest that a high arsenic metabolization capacity has been selected as an adaptive mechanism in these populations in order to survive in an arsenic-laden environment, the researchers conclude (American Journal of Physical Anthropology, doi.org/bz4s).

                The variants that protect the Camarones people are called single nucleotide polymorphisms changes in a single DNA letter of the genetic code. Anthropologist Lorena Madrigal of the University of South Florida in Tampa says these are such tiny mutations that they arent telling us exactly how the changes affect the enzyme molecule and its detoxifying effects.

                Previous studies found similar mutations in the AS3MT gene that contribute to improved arsenic metabolisation in Vietnam and Argentina. Sequencing the entire chromosomal region around this gene could reveal more, but theres still a long way to go before we fully understand the molecular mechanism for how arsenic resistance works.

                Though its a fascinating example of what appears to be contemporary evolution in humans, it also underscores the water quality problems that many populations face, says Madrigal. And many may not be able to evolve to deal with it.

                I'm always still in trouble again

                "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
                "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
                "Of course, human life begins at fertilization that’s not the argument." --Tassman

                Comment


                • #83
                  Originally posted by rogue06 View Post
                  I probably should include this one as well, which I posted about in 2017
                  I wonder if those variants exist in Bangladesh.
                  Jorge: Functional Complex Information is INFORMATION that is complex and functional.

                  Mountain Man: First of all, the Bible is a fixed document.
                  Mountain Man on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
                  Mountain Man on climate change: Looking at the historical temperature data in my region over the past ten years shows that temperatures have been stable ...

                  Comment


                  • #84
                    Originally posted by Roy View Post
                    I wonder if those variants exist in Bangladesh.
                    I've heard that portions of the country have water with a high arsenic content, are those drinking it suffering no deleterious effects?

                    I'm always still in trouble again

                    "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
                    "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
                    "Of course, human life begins at fertilization that’s not the argument." --Tassman

                    Comment


                    • #85
                      Originally posted by rogue06 View Post
                      I've heard that portions of the country have water with a high arsenic content, are those drinking it suffering no deleterious effects?
                      No, they're suffering lots of deleterious effects. Those variants would, if they exist there, be highly favoured.

                      (The problem is not that the water there has a high arsenic content, it's that dense populations are using so much water that wells are having to be deepened into arsenic bearing strata.)
                      Last edited by Roy; 11-05-2022, 09:22 AM.
                      Jorge: Functional Complex Information is INFORMATION that is complex and functional.

                      Mountain Man: First of all, the Bible is a fixed document.
                      Mountain Man on covid-19: We're talking about an illness with a better than 99.9% rate of survival.
                      Mountain Man on climate change: Looking at the historical temperature data in my region over the past ten years shows that temperatures have been stable ...

                      Comment


                      • #86
                        Originally posted by Roy View Post
                        No, they're suffering lots of deleterious effects. Those variants would, if they exist there, be highly favoured.

                        (The problem is not that the water there has a high arsenic content, it's that dense populations are using so much water that wells are having to be deepened into arsenic bearing strata.)
                        It goes to show that just because an organism (in this case, us) has a need for some sort of mutation doesn't mean it will take place.

                        I'm always still in trouble again

                        "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
                        "Overall I would rate the withdrawal from Afghanistan as by far the best thing Biden's done" --Starlight
                        "Of course, human life begins at fertilization that’s not the argument." --Tassman

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                        • #87
                          An article discussing several beneficial mutations in humans, including a few not previously mentioned

                          Source: 8 Genetic Mutations That Can Give You 'Superpowers'


                          More than 99 percent of your genetic information is exactly the same as every other person on the planet. Your genes determine your skin colour, sex, and hair colour and whether or not you have certain genetic diseases.

                          But it's in that less than 1 percent that things get interesting. Specific genetic variations allow some of us to acquire certain - dare we say super - qualities. Here are the ways our genes can predispose us to have special abilities.

                          ACTN3 and the super-sprinter variant

                          We all have a gene called ACTN3, but certain variants of it help our bodies make a special protein called alpha-actinin-3. This protein controls fast-twitch muscle fibres, the cells responsible for the speedy tensing and flexing of the muscles involved in sprinting or weight-lifting.

                          This discovery, which happened around 2008 when geneticists studying elite sprinters and power athletes found that very few among them had two defective ACTN3 copies, is what led to the gene being dubbed the 'sports gene'.

                          Among the general population, however, some 18 percent of us are completely deficient in the speedy-muscle-contracting protein - we inherited two defective copies of ACTN3.

                          hDEC2 and the super-sleeper mutation

                          Imagine if you could feel totally energised on just 4 hours of sleep each night. Some people are naturally that way.

                          These people are called 'short-sleepers', and scientists are only recently uncovering what exactly predisposes them to be this way.

                          For the most part, researchers believe that the capabilities are connected to specific genetic mutations, and have publicly identified one on the hDEC2 gene.

                          That means that short-sleeping habits can run in the family, and scientists hope to one day learn how to harness this ability so it can be used to help people switch up their sleeping routines.

                          TAS2R38 and the supertaster variant

                          About a quarter of the population tastes food way more intensely than the rest of us.

                          These 'super tasters' are more likely to put milk and sugar in bitter coffee, or avoid fatty foods. The reason for their reaction, scientists think, is programmed into their genes, specifically one called TAS2R38, the bitter-taste receptor gene.

                          The variant responsible for super tasting is known as PAV, while the variant responsible for below-average tasting abilities is known as AVI.

                          LRP5 and the unbreakable mutation

                          Brittle bones pose a big problem. Researchers have identified a genetic mutation on the LRP5 gene that regulates bone-mineral density, which can cause brittle, weak bones.

                          So far, scientists have identified multiple mutations to the LRP5 gene that appear to be linked with bone conditions, including juvenile primary osteoporosis and osteoporosis-pseudoglioma syndrome.

                          But a different type of mutation on the same gene could also have the opposite effect, giving some people extremely dense bones that are practically unbreakable.

                          The malaria-protecting variant

                          People who are carriers for sickle-cell disease - meaning that they have one sickle gene and one normal haemoglobin gene - are more protected against malaria than those who are not.

                          Though blood disorders are not necessarily 'super', this information may influence more innovative malaria treatments down the road.

                          CETP and the low-cholesterol mutation

                          Although environment - including what we eat - can influence cholesterol levels, genetics play a big role, too.

                          Mutations in a gene responsible for producing a protein called cholesteryl ester transfer protein (CETP) result in a deficiency of that protein. CETP deficiency is linked with having higher levels of 'good' HDL cholesterol, which helps carry cholesterol to the liver so it can be removed from the body, resulting in lower cholesterol levels.

                          Studies have also found a lower prevalence of coronary heart disease in people with the deficiency-causing mutation.

                          BDNF and SLC6A4 and the super coffee-drinker variants

                          There are at least six genes associated with how your body processes caffeine.

                          Some variants, near the genes BDNF and SLC6A4, influence the rewarding effects of caffeine that make you want to drink more.

                          Others are linked to how the body metabolises caffeine - those who break caffeine down more quickly may be more likely to drink more of it because the effects wear off faster.

                          Others still help explain why some people are able to fall asleep at night after their daily morning coffee while others have to cut out the habit altogether to get a good night's sleep.

                          ALDH2*2: The super-flusher variant

                          Do your cheeks go rosy shortly after having a single glass of wine? A mutation on the ALDH2 gene may be the culprit.

                          One such mutation interferes with the ability of a liver enzyme called ALDH2 to convert the alcohol byproduct acetaldehyde into acetate.

                          When acetaldehyde builds up in the blood, it opens up the capillaries, causing what we see as a flush or glow.

                          But there's another dangerous component of acetaldehyde - it's a carcinogen in people, and research suggests that people who flush when they drink alcohol may have the mutation and may also be at a greater risk of esophageal cancer.



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                          "Of course, human life begins at fertilization that’s not the argument." --Tassman

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