<p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><em style="line-height: inherit;">With great power, comes great responsibility</em><br></p>
<p></p><center style="color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);">- Uncle Ben</center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmdXh8qR8XLRxL5R3mMKHiQWwTkCkjqbgRaJ3nxRFr2iRv/800px-Gene_Drive.png" alt="800px-Gene_Drive.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><center style="color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><span style="font-weight: 600; line-height: inherit;">Normal inheritance VS Gene drive</span><br><a href="https://commons.m.wikimedia.org/wiki/File:Gene_Drive.png" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Mariuswalter | <a href="https://creativecommons.org/licenses/by-sa/4.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC BY-SA 4.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">The technology I am going to describe today, holds great potential. It can help to eradicate vector borne diseases. Such as, malaria and dengue which spreads by mosquitoes. It can help eradicate invasive species that hinders agriculture. It can help modify not just few organisms, but entire populations and species, to look and behave, the way we desire. Given it holds such power, the onus of using it responsibly also lies on us. Here my job is to make you aware of how it works. Because if society understands technology better, they should be able to make informed choices for their future.</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Mendelian genetics for newbies</h1><div class="pull-left" style="margin: 0px; padding-top: 0px; padding-bottom: 0px; padding-left: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmbmVP1fHedggTMkXeSoZUTgjVQi4dbncWSqXPqufLWzmj/1100px-Punnett_square_mendel_flowers.svg.png" alt="1100px-Punnett_square_mendel_flowers.svg.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">An example of mendelian inheritance. When two plants having purple flower are crossed, and both plants are heterozygous for gene B that makes the color purple. That is they have purple gene B amd white gene b (but flower is white if and only if, plant carries two copies of b). The heterozygous plants produce 50% B gametes and 50% b gametes. The cross results in 75% purple flower plants and 25% white flower plants.</span><br><a href="https://kn.m.wikipedia.org/wiki/%E0%B2%9A%E0%B2%BF%E0%B2%A4%E0%B3%8D%E0%B2%B0:Punnett_square_mendel_flowers.svg" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Madprime | <a href="https://creativecommons.org/publicdomain/zero/1.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC0 1.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Every sexually reproducing organism carry 2 copies of genes in their genome, on homologous chromosomes. The two copies of genes can be identical, in which case we will call the animal homozygous for this genetic locus. In other cases, the organism can have similar but not identical sequence of same gene, on their homologous chromosomes. Or you can say that the organism carries two different alleles of the same gene and is hence heterozygous for this genetic locus.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">When the sexual gametes form they randomly pick one of the two chromosomes. And hence one of the two alleles from the same chromosome. So if there was a gene G on some chromosome, and g on the other - then 50% of sperms of this organism will carry G and other 50% will carry g. Similarly if the female as well have G and g alleles, then 50% of eggs formed in this female will only have G and 50% of them will have g.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">During the mating, there are 4 possible combinations of sperm and egg thar can form - GG,Gg,gG,gg. Therefore, if this male and female pair makes 100 kids in their lifetime 25 of them will be GG, 25 will be gg, and the rest 50 of them will be Gg. If G was a dominant gene which makes the organism green, the 75% of offsprings have GG, gG or Gg will be green. And 25% gg offsprings will be white (see <a href="https://en.wikipedia.org/wiki/Mendelian_inheritance" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Mendelian inheritance</a>).</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Population genetics</h1><div class="pull-right" style="margin: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmVBNYMSkJKCNwfs6TZJKQjjyYmAbAZYmNePF3ypGbc9fZ/images%20(3).png" alt="images (3).png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">Hardy-weinberg equilibrium.</span> In a very large population, mating randomly, and under no selection pressure for any allele, the allelic frequencies stays constant in generations.<br><a href="https://commons.m.wikimedia.org/wiki/File:Hartsock_Hardy_Weinberg_Example.png" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Angelahartsock | <a href="https://creativecommons.org/publicdomain/zero/1.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC0 1.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Say, individuals in a very large population who are randomly mating, and have no selection pressure on their color carry alleles. Say, in this population 70% individuals carry allele, G. Then what is the frequency of different genotypes and phenotypes in the population?</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><a href="https://en.m.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Hardy-Weinberg</a> equation tells us that, in such a situation.<br>Frequency of:<br>gg + 2Gg + GG<br>0.3<span style="font-size: 14.4px; line-height: 0; position: relative; vertical-align: baseline; top: -0.5em;">2</span> + 2<em style="line-height: inherit;">0.3</em>0.7 + 0.7<span style="font-size: 14.4px; line-height: 0; position: relative; vertical-align: baseline; top: -0.5em;">2</span></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">0.09 + 0.42 + 0.49 = 1 is a population in HW equilibrium. The next generation will now have same allele frequencies. G = 0.7 and g = 0.3. This will continue generation after generation in this population. Unless, the for some reason the gene frequency changes, we will always have 91% green, 9% white organisms in the population - generation after generation. The gene frequency may change because green individuals prefer other green individuals for mating. Or because, either green or white individuals are more likely to die because of some pathogenic disease.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">This, would always be the outcome provided every gene on every chromosome behaved in Mendelian manner, and there is no selection pressure. But, what about crossing over and recombination that happens during gamete formation?</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Recombining genes</h1><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmdr2FgkbKMLN6E2m3QZPYTSYggayBMoFk2tyTTbV193re/1600px-Meiosis_main_steps.svg.png" alt="1600px-Meiosis_main_steps.svg.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><center style="color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><span style="font-weight: 600; line-height: inherit;">Schematic of meiosis, that happens during gamete formation.</span> DNA in diploid cell duplicates and each chromosome now have sister chromatids (1). Each chromosome then pairs with its homologous pair in the genome (2). Crossover takes place between homologous chromosomes and DNA is exchanged, any errors repaired (3). Cell divides into 2 each carrying one of two chromosomes from the homologous pair (4). The second division happens by mitosis where both cells take one sister chromatid, making a total of 4 haploid cells. Each cell now contain only one copy of chromosome (5).<br><a href="https://commons.m.wikimedia.org/wiki/File:Meiosis_main_steps.svg" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Peter Coxhead | <a href="https://creativecommons.org/publicdomain/zero/1.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC0 1.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><div class="pull-left" style="margin: 0px; padding-top: 0px; padding-bottom: 0px; padding-left: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmaFwpy86Le2DPrTMBr6akJcgg4PRtQ6eRvZCp1aUhrudh/1600px-Crossing-over_scheme_PL.svg.png" alt="1600px-Crossing-over_scheme_PL.svg.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">Chromosomal crossing over. Showing two strands of DNA sister chromatid exchanging DNA</span><br><a href="https://commons.m.wikimedia.org/wiki/File:Crossing-over_scheme_PL.svg" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Masur | <a href="https://en.m.wikipedia.org/wiki/Public_domain" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Public domain</a>.<br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">When the gametes form, they undergo a process called meiosis. In meiosis, the chromosomes segregates and each diploid germ cell forms 4 haploid gametes. Anyhow, during the process of meiosis, the homologous chromosomes come close together. They recognise each other, by their sequence similarity. But this sequence similarity and their closing in, also enables them to exchange DNA and repair each other. In this process called recombination one or more genes on the chromosome cross-over. Which means they bind together by forming bonds between complementary strands. If the mismatch is found, then the DNA repair enzymes copies sequence of one of the gene to other. This creates a possibility that a organism which was heterozygous for some gene, produces gametes of only one of them, as if it was homozygous.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">However, for most part cells don't know which gene is the correct one. Which allele will copy onto the other is a random choice. Hence, it a germ cell containing G and g, during a crossover will become homozygous for G or g has equal probability.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">So say if chance of crossover at gene locus was 10% then in population there will be individuals which may bias the number of G gametes by 10%. But at the same time there will be individuals who may have biased the number of g containing gametes. Hence, in a large population, and in long run the effect of recombination would cancel out. Yet again maintaining the allele frequencies like they were in the parent generation. However, not always.</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Meet the gene drive</h1><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">What if, during the recombination process g is always biased to replace G? Maybe g even induces the recombination event at this site. Well, if this was to happen, say 90% of the time then - in the next generation the population will have 90% more gametes of g, than expected.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">So if frequency of g was 0.3 in the population. Instead of producing. 30% of g gametes were supposed to come from gg and Gg genotypes. But since 90% of Gg's germ cell will change to gg you will be left with 4.2 Gg and 38.8% more gg. Which means that in next generation you will have 49.9 g gametes and only 51.1 G gametes. This will bias the frequency towards g in the population. It will keep increasing in every generation through heterozygotes, until it reaches an equilibrium state; even if being white (gg) was detrimental over being green (GG or Gg). We can simulate different scenarios for fun in another post, if you like.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Anyhow, what we must focus on asking is - do such examples exist in nature? And if yes, then how do we exploit them?</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Natural examples of gene drive</h1><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">There are two major examples of naturally occuring gene drive found in nature.</p><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Transposable elements</h2><div class="pull-right" style="margin: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmd6jP2ogBgAMF92pgJNMqNMsEcJWJoisXkEVWChZSiwdY/Retrotransposons.png" alt="Retrotransposons.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">Retrotransposons produce a RNA copy from the existing gene. This RNA is then converted back to DNA via a reverse transcriptase and incorporated into a new place into the genome</span><br><a href="https://commons.m.wikimedia.org/wiki/File:Retrotransposons.png" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Mariuswalter| <a href="https://creativecommons.org/licenses/by-sa/4.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC BY-SA 4.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Transposons or jumping genes are sequences in the genome, which makes their copies and inserts this copy to a new site in the genome. This increases their frequency in next generation.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Take P element in fruit flies for example. If you inserted a gene of your interest within the P element; and insert that P element into some of the individuals within population, soon the gene will spread throughout the population (<a href="https://www.ncbi.nlm.nih.gov/m/pubmed/9465407/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Carareto et al., 1997</a>).</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Even humans have such jumping genes. Take example of retrotransposons. These are remains of ancient retroviruses (cousins of HIV), that left their genetic material in us. They are well known to move around and expand in our genome - by copying complete or partial gene sequences at new places in our genome. (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5631067/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">JanouΕ‘ek et al., 2016</a>).</p><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Homing endonuclease genes.</h2><div class="pull-left" style="margin: 0px; padding-top: 0px; padding-bottom: 0px; padding-left: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmRk38ehNqadNqCPk74KkofHuTSuR17c9GMHCq3Nfmfe2E/images%20(40).jpeg" alt="images (40).jpeg" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">Double stranded breaks in DNA can initiate either Non homologous end joining or homology directed repair. The enzyme that make double stranded breaks can hence also initiate there processes.</span><br><a href="https://ml.m.wikipedia.org/wiki/%E0%B4%AA%E0%B5%8D%E0%B4%B0%E0%B4%AE%E0%B4%BE%E0%B4%A3%E0%B4%82:16_Hegasy_DNA_Rep_Wiki_E_CCBYSA.png" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Guido4 | <a href="https://creativecommons.org/licenses/by-sa/4.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC BY-SA 4.0</a><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Note that, homologous recombination can also be initiated by damage. That is if DNA has a double stranded break, then it will try to repair it. The repair can happen either by non homologous end joining, or by homology directed repair (HDR). Its is HDR where in order to repair the damage the homologous sequence is used as a template.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Homing endonuclease genes (HEG) produces an enzyme that cuts a specific sequence in the genome as recognized by the enzyme. Once the cut has been made, the double stranded break machinery is deployed to repair it.</p><div class="pull-right" style="margin: 0px; padding-top: 0px; padding-right: 0px; padding-bottom: 0px; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmVqvEV78TyVkemRC4Zy6PHTam8SZtST1cUQMWduhtgr2E/IMG_20190210_224501.jpg" alt="IMG_20190210_224501.jpg" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p><center><span style="font-weight: 600; line-height: inherit;">Mechanism of action of gene drive by homing endonucleases.</span> When the site of cut of HEG is spanned by homologous sequences on two chromosomes, the HEG is incorporated into the new dite via homology directed repair.<br><em style="line-height: inherit;">Doodled by <a href="https://steemit.com/@scienceblocks" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">@scienceblocks</a></em><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"></p></div><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">If the site of cut is spanned by sequence similar to that spanning HEG, then HEG is inserted at the new site. This situation is of course more likely to happen between same locus on two homologous chromosomes (and, it is more frequent during meiosis). This biases the copying of HEG from HEG containing chromosome to non HEG containing chromosome. This ends up increasing the frequency of HEG containing chromosome in the population (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691325/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Burt et al., 2003</a>). Anyway, what this hints at is that if you control where to make the cut, you can control and bias the recombination of genes.</p><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Active genetics - exploiting the gene drive for human benefits</h1><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">If nature can do it, so can we. The potential of using gene drive for designing and exterminating wild type insect populations, has been recognized since 1960s (<a href="https://www.nature.com/articles/218368a0" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Curtis, 1968</a>). But the biotechnological tools to do it efficiently, only became available in the end of 20th century. It was the time, when restriction enzymes came into picture. I mean imagine if you can attach an HEG gene to a gene of your interest, and span it with sequences that causes recombination at site of your choice (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691325/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Burt et al., 2003</a>). This should enable you to design artificial gene drives, when you release the lab made populations into the wild. However, you will be limited by constraints that your locus of interest in the genome, should have a DNA sequence that can be recognized by HEG.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">You can however overcome this constraint by either mutating the HEG to recognize a DNA sequence of your desire or by engineering <a href="https://en.m.wikipedia.org/wiki/Transcription_activator-like_effector_nuclease" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">TALEN</a> or <a href="https://en.m.wikipedia.org/wiki/Zinc_finger_nuclease" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">ZFNs</a> proteins that cut DNA at site you engineered it for. But, if and only if, we had an endonuclease which doesn't have to be designed every time but just programmed to cut at specific site. I guess we know one - they call it Cas9.</p><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">CRISPR-Cas9 based gene drives</h2><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQmQPxbWfdwAf88K5vwYuok1vDr73j6DieYH7mSji1yLbtn/Molecular_mechanism_of_gene_drive.svg.png" alt="Molecular_mechanism_of_gene_drive.svg.png" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><center style="color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><span style="font-weight: 600; line-height: inherit;">Design of a mutagenic chain reaction cassette.</span> A plasmid containing Cas9 gene, gRNA, a payload gene (if required) and homologous sequences to target sites (H1 and H2) is inserted into the organism (Top left). The gRNA cuts at the target site. This starts a homology directed repair aided by H1 and H2 and inserts the entire cassette at the target site (bottom left). When a heterozygous animal carries this MCR cassette in one of its chromosome, it also causes it to insert it into the homologous chromosome (top and bottom right).<br><a href="https://commons.m.wikimedia.org/wiki/File:Molecular_mechanism_of_gene_drive.svg" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Image</a> by Thomas Julou | <a href="https://creativecommons.org/licenses/by-sa/4.0/deed.en" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">CC BY-SA 4.0</a>.<br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">If you are unaware of how CRISPR-Cas9 system works, I recommend you read my <a href="https://steemit.com/steemstem/@scienceblocks/journey-from-adaptive-immunity-in-bacteria-crispr-to-saving-man-s-best-friend-dog-8b43829c367d9" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">previous blog</a>. The crux of the matter is that - you can just design a sequence of guide RNA (gRNA), complementary to site where you want to make a double stranded cut. The Cas9 enzyme bound to gRNA will bind to region where it matches and make a double stranded break. This will start the break repair process. Now if you had your gene if interest fused with Cas9-gRNA genes, bounded by some homologous sequence, the repair machinery will insert this cassette, into the strand it is repairing. And hence, you have created a programmable, and site specific tool to create artificial gene drive. Which brings us to the question of how to use it.</p><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Gene drive user manual - examples</h2><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Now that you are aware of tools that can be used to create artificial gene drives, we can visit some examples of its utility.</p><h3 style="margin: 2rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 23.04px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">Manipulating traits</h3><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">In 2015, <a href="http://science.sciencemag.org/content/348/6233/442" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Gantz and Bier</a> designed a Cas9-gRNA cassette flanked by sequences homologus to yellow gene found on X chromosomes of Drosophila. The called this gene a mutagenesis chain reaction or MCR. A recessive homozygous female mutant for this gene (in which both copies of gene are mutated) and all male mutants (because they only have one X chromosome), will have yellow colouration in the cuticle of the flies. Under normal scenario a yellow female (homozygous mutant for y, y-), crossed with y+ male, should give all yellow males and no yellow females in 1st generation. In second generation these hetrozygous y+/y- females, with y- males, should yield 25% of yellow females, 25% yellow males, 25% non yellow females and 25% non yellow males. However, for Gantz and Bier who introduced y- mutation by MCR construct, this did not happen. Instead, they got about 49% yellow males, 47 % yellow females. Only the remaining 4% were non yellow or mosiac individuals. If you were to release the MCR containing flies in the wild, in matter of few generations the yellow flies will be all over the pace.</p><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">How to eradicate malaria</h2><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><img src="https://steemitimages.com/640x0/https://cdn.steemitimages.com/DQma3ZgHph7AXNkiuKCPSk8uGhRQV8mStZpVNXWsRhwjMDN/IMG_20190210_225008.jpg" alt="IMG_20190210_225008.jpg" style="border-style: none; display: inline-block; vertical-align: middle; height: auto; width: auto; max-height: none;"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><center style="color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><span style="font-weight: 600; line-height: inherit;">Schematic of 17000 bp construct designed by Gantz et al., 2015.</span><br></center><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"></p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Alright then, if we can spread the MCR construct to modify the color of flies, can we use it for something more productive? How about eradicate malaria? Malaria is spread by female mosquito Anopheles <em style="line-height: inherit;">stephensi</em>. There are many proposed ways to spread genes in mosquito populations that would make the females infertile, or change the sex bias to males via meiotic drive. But my favorite one is to use the mutagenic chain reaction construct, carrying the genes that make the mosquitos incapable of carrying the germ, Plasmodium <em style="line-height: inherit;">falciparum</em>.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);"><a href="https://www.pnas.org/content/early/2015/11/18/1521077112.abstract" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Gantz et al., 2015</a>, designed such a construct. Their construct had 2 effector genes, namely m2A10 and m1C3, both of which disables spores of Plasmodium <em style="line-height: inherit;">falciparum</em> to accumulate in saliva of Anopheles <em style="line-height: inherit;">stephensi</em>. These genes were fused with gene for red fluorescent marker along with gRNA and Cas9. The gRNA was designed to make Cas9 cut the Kh gene locus in mosquito. Mutation of this gene causes mosquitos to have white eyes. Hence , mosquitos that will have MCR gene will have white eyes. Finally, the entire construct was flanked on both sides by sequence that promotes homology directed repair at Kh locus. Using this construct Gantz and the team were able to make mosquitoes that do not spread malaria and spread this gene through the population at 99% rate.</p><hr style="box-sizing: content-box; overflow: visible; clear: both; max-width: 75rem; margin: 1.25rem auto; border-top: 0px; border-right: 0px; border-left: 0px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">I can talk about more strategies and examples. But I think you get the point. Using CRISPR-Cas based gene drive we can design the entire wild populations. Be it eradicating diseases, getting rid of pests from our crops, or modifying rodent populations (<a href="https://www.nature.com/articles/s41586-019-0875-2" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Grunwald et al, 2019</a>). Whatever, your need be, the gene integration or deletion can be done for entire populations and not just individuals. Though, you are limited by generation time. For instance if you wanted to modify entire human population and gene reached 99% of people in 20 generations, it may take you centuries to achieve your goal.</p><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; background-color: rgb(252, 252, 252);">Another issue, as you might have guessed (and why eradication of malaria has not started in wild), is because of ethical concerns. Just because we can play God with genes, should we do it, is what haunts us. What if we miss something and something goes wrong? I will leave you with that question to wonder about.</p><hr style="box-sizing: content-box; overflow: visible; clear: both; max-width: 75rem; margin: 1.25rem auto; border-top: 0px; border-right: 0px; border-left: 0px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: "Source Serif Pro", serif; font-size: 19.2px; background-color: rgb(252, 252, 252);"><h2 style="margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; font-size: 26.88px; line-height: 1.2 !important;">About steemstem</h2><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">But before I go I would like to mention about the steemstem platform. Well, if you love reading and writing interesting science articles </span><a href="https://steemit.com/@steemstem" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">@steemstem</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> is a community on steem that support authors and content creators in STEM field. If you wish to support steemstem do see the links below.</span><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">You can vote for steemstem witness here -</span><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">Quick link for </span><a href="https://steemconnect.com/sign/account_witness_vote?approve=1&witness=stem.witness" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">voting for the SteemSTEM Witness</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">(</span><a href="https://steemit.com/@stem.witness" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">@stem.witness</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">)</span><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">Delegation links for </span><a href="https://steemit.com/@steemstem" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">@steemstem</a><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">Quick delegation links: </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=50%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">50SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> | </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=100%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">100SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> | </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=500%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">500SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> | </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=1000%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">1000SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> | </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=5000%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">5000SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> | </span><a href="https://steemconnect.com/sign/delegateVestingShares?delegator=&delegatee=steemstem&vesting_shares=10000%20SP" rel="noopener" title="This link will take you away from steemit.com" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">10000SP</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">).</span><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility; font-family: "Source Serif Pro", serif; font-weight: 400; background-color: rgb(255, 255, 255);"></p><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);">Delegating to </span><a href="https://steemit.com/@steemstem" style="background-color: rgb(255, 255, 255); line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;">@steemstem</a><span style="font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400; background-color: rgb(255, 255, 255);"> gives ROI of 65% of the curation rewards.</span><br></h1><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;"><br></h1><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;">References</h1><h1 style="font-size: 30.72px; margin: 2.5rem 0px 0.3rem; padding: 0px; font-family: "Source Sans Pro", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); text-rendering: optimizelegibility; background-color: rgb(252, 252, 252); line-height: 1.2 !important;"><ol style="margin: 0px 0px 1rem 2rem; padding: 0px; list-style-position: outside; line-height: 1.6; font-family: "Source Serif Pro", serif; font-size: 19.2px; font-weight: 400;"><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://en.wikipedia.org/wiki/Mendelian_inheritance" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Mendelian inheritance</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://en.m.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">HardyβWeinberg principle</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.ncbi.nlm.nih.gov/pubmed/9465407/?ncbi_mmode=std" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Carareto CM, Kim W, Wojciechowski MF, O'Grady P, Prokchorova AV, Silva JC, Kidwell MG. Testing transposable elements as genetic drive mechanisms using Drosophila P element constructs as a model system. Genetica. 1997;101(1):13-33. PubMed PMID: 9465407.</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5631067/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">JanouΕ‘ek V, Laukaitis CM, Yanchukov A, Karn RC. The Role of Retrotransposons in Gene Family Expansions in the Human and Mouse Genomes. Genome Biol Evol. 2016;8(9):2632-50. Published 2016 Aug 8. doi:10.1093/gbe/evw192</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1691325/" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Burt A. Site-specific selfish genes as tools for the control and genetic engineering of natural populations. Proc Biol Sci. 2003;270(1518):921-8.</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.nature.com/articles/218368a0" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Curtis, 1968. Possible Use of Translocations to fix Desirable Genes in Insect Pest Populations</a>.</p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://en.m.wikipedia.org/wiki/Transcription_activator-like_effector_nuclease" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">TALENs</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://en.m.wikipedia.org/wiki/Zinc_finger_nuclease" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">ZFNs</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://steemit.com/steemstem/@scienceblocks/journey-from-adaptive-immunity-in-bacteria-crispr-to-saving-man-s-best-friend-dog-8b43829c367d9" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Journey from adaptive immunity in bacteria(CRISPR) to saving Man's best friend(Dog).</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="http://science.sciencemag.org/content/348/6233/442" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Gantz and Bier, 2015. The mutagenic chain reaction: A method for converting heterozygous to homozygous mutations</a></p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.pnas.org/content/early/2015/11/18/1521077112.abstract" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Gantz et al., 2015. Highly efficient Cas9-mediated gene drive for population modification of the malaria vector mosquito Anopheles stephensi</a>.</p></li><li style="margin: 0px; padding: 0px; font-size: inherit;"><p style="margin-bottom: 1.5rem; padding: 0px; font-size: 19.2px; line-height: 28.8px; text-rendering: optimizelegibility;"><a href="https://www.nature.com/articles/s41586-019-0875-2" rel="noopener" title="This link will take you away from steemit.com" style="line-height: inherit; color: rgb(31, 191, 143); cursor: pointer; transition: all 0.2s ease-in-out 0s;">Grunwald et al., 2019. Super-Mendelian inheritance mediated by CRISPRβCas9 in the female mouse germline</a>.</p></li></ol></h1><p></p>