Topic: Molecular Biology/Molecular and Cell Biology
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π Alan Turing's 100th Birthday - Mathematician, logician, cryptanalyst, scientist
Alan Mathison Turing (; 23 June 1912Β β 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical computer science, providing a formalisation of the concepts of algorithm and computation with the Turing machine, which can be considered a model of a general-purpose computer. Turing is widely considered to be the father of theoretical computer science and artificial intelligence. Despite these accomplishments, he was not fully recognised in his home country during his lifetime, due to his homosexuality, and because much of his work was covered by the Official Secrets Act.
During the Second World War, Turing worked for the Government Code and Cypher School (GC&CS) at Bletchley Park, Britain's codebreaking centre that produced Ultra intelligence. For a time he led Hut 8, the section that was responsible for German naval cryptanalysis. Here, he devised a number of techniques for speeding the breaking of German ciphers, including improvements to the pre-war Polish bombe method, an electromechanical machine that could find settings for the Enigma machine.
Turing played a crucial role in cracking intercepted coded messages that enabled the Allies to defeat the Nazis in many crucial engagements, including the Battle of the Atlantic, and in so doing helped win the war. Due to the problems of counterfactual history, it is hard to estimate the precise effect Ultra intelligence had on the war, but at the upper end it has been estimated that this work shortened the war in Europe by more than two years and saved over 14Β million lives.
After the war Turing worked at the National Physical Laboratory, where he designed the Automatic Computing Engine. The Automatic Computing Engine was one of the first designs for a stored-program computer. In 1948 Turing joined Max Newman's Computing Machine Laboratory, at the Victoria University of Manchester, where he helped develop the Manchester computers and became interested in mathematical biology. He wrote a paper on the chemical basis of morphogenesis and predicted oscillating chemical reactions such as the BelousovβZhabotinsky reaction, first observed in the 1960s.
Turing was prosecuted in 1952 for homosexual acts; the Labouchere Amendment of 1885 had mandated that "gross indecency" was a criminal offence in the UK. He accepted chemical castration treatment, with DES, as an alternative to prison. Turing died in 1954, 16 days before his 42nd birthday, from cyanide poisoning. An inquest determined his death as a suicide, but it has been noted that the known evidence is also consistent with accidental poisoning.
In 2009, following an Internet campaign, British Prime Minister Gordon Brown made an official public apology on behalf of the British government for "the appalling way he was treated". Queen Elizabeth II granted Turing a posthumous pardon in 2013. The Alan Turing law is now an informal term for a 2017 law in the United Kingdom that retroactively pardoned men cautioned or convicted under historical legislation that outlawed homosexual acts.
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- "Alan Turing died 70 years ago" | 2024-06-07 | 103 Upvotes 136 Comments
- "Alan Turing's 100th Birthday - Mathematician, logician, cryptanalyst, scientist" | 2012-06-22 | 146 Upvotes 19 Comments
- "Happy Birthday, Alan Turing" | 2011-06-23 | 78 Upvotes 6 Comments
π Peto's Paradox
Peto's paradox is an observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. For example, the incidence of cancer in humans is much higher than the incidence of cancer in whales, despite whales having more cells than humans. If the probability of carcinogenesis were constant across cells, one would expect whales to have a higher incidence of cancer than humans. Peto's paradox is named after English statistician and epidemiologist Richard Peto, who first observed the connection.
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- "Peto's Paradox" | 2022-11-05 | 142 Upvotes 68 Comments
π HeLa, the oldest and most commonly used human cell line
HeLa (; also Hela or hela) is an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken on February 8, 1951 from Henrietta Lacks, a patient who died of cancer on October 4, 1951. The cell line was found to be remarkably durable and prolific, which gives rise to its extensive use in scientific research.
The cells from Lacks's cancerous cervical tumor were taken without her knowledge or consent, which was common practice at the time. Cell biologist George Otto Gey found that they could be kept alive, and developed a cell line. Previously, cells cultured from other human cells would only survive for a few days. Scientists would spend more time trying to keep the cells alive than performing actual research on them. Cells from Lacks' tumor behaved differently. As was custom for Gey's lab assistant, she labeled the culture 'HeLa', the first two letters of the patient's first and last name; this became the name of the cell line.
These were the first human cells grown in a lab that were naturally "immortal", meaning that they do not die after a set number of cell divisions (i.e. cellular senescence). These cells could be used for conducting a multitude of medical experimentsβif the cells died, they could simply be discarded and the experiment attempted again on fresh cells from the culture. This represented an enormous boon to medical and biological research, as previously stocks of living cells were limited and took significant effort to culture.
The stable growth of HeLa enabled a researcher at the University of Minnesota hospital to successfully grow polio virus, enabling the development of a vaccine, and by 1952, Jonas Salk developed a vaccine for polio using these cells. To test Salk's new vaccine, the cells were put into mass production in the first-ever cell production factory.
In 1953, HeLa cells were the first human cells successfully cloned and demand for the HeLa cells quickly grew in the nascent biomedical industry. Since the cells' first mass replications, they have been used by scientists in various types of investigations including disease research, gene mapping, effects of toxic substances on organisms, and radiation on humans. Additionally, HeLa cells have been used to test human sensitivity to tape, glue, cosmetics, and many other products.
Scientists have grown an estimated 50 million metricΒ tons of HeLa cells, and there are almost 11,000Β patents involving these cells.
The HeLa cell lines are also notorious for invading other cell cultures in laboratory settings. Some have estimated that HeLa cells have contaminated 10β20% of all cell lines currently in use.
Discussed on
- "HeLa, the oldest and most commonly used human cell line" | 2015-10-30 | 54 Upvotes 12 Comments
- "Immortal cells of Henrietta Lacks" | 2010-02-01 | 36 Upvotes 7 Comments
π Sonic Hedgehog Protein (encoded by the SHH gene)
Sonic hedgehog protein (SHH) is encoded for by the SHH gene. The protein is named after the character Sonic the Hedgehog.
This signaling molecule is key in regulating embryonic morphogenesis in all animals. SHH controls organogenesis and the organization of the central nervous system, limbs, digits and many other parts of the body. Sonic hedgehog is a morphogen that patterns the developing embryo using a concentration gradient characterized by the French flag model. This model has a non-uniform distribution of SHH molecules which governs different cell fates according to concentration. Mutations in this gene can cause holoprosencephaly, a failure of splitting in the cerebral hemispheres, as demonstrated in an experiment using SHH knock-out mice in which the forebrain midline failed to develop and instead only a single fused telencephalic vesicle resulted.
Sonic hedgehog still plays a role in differentiation, proliferation, and maintenance of adult tissues. Abnormal activation of SHH signaling in adult tissues has been implicated in various types of cancers including breast, skin, brain, liver, gallbladder and many more.
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- "Sonic Hedgehog Protein (encoded by the SHH gene)" | 2023-01-26 | 58 Upvotes 43 Comments
π Foldit
Foldit is an online puzzle video game about protein folding. It is part of an experimental research project developed by the University of Washington, Center for Game Science, in collaboration with the UW Department of Biochemistry. The objective of Foldit is to fold the structures of selected proteins as perfectly as possible, using tools provided in the game. The highest scoring solutions are analyzed by researchers, who determine whether or not there is a native structural configuration (native state) that can be applied to relevant proteins in the real world. Scientists can then use these solutions to target and eradicate diseases and create biological innovations. A 2010 paper in the science journal Nature credited Foldit's 57,000 players with providing useful results that matched or outperformed algorithmically computed solutions.
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- "Foldit" | 2024-02-18 | 53 Upvotes 15 Comments
π Confocal microscopy
Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures (a process known as optical sectioning) within an object. This technique is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection and materials science.
Light travels through the sample under a conventional microscope as far into the specimen as it can penetrate, while a confocal microscope only focuses a smaller beam of light at one narrow depth level at a time. The CLSM achieves a controlled and highly limited depth of field.
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- "Confocal microscopy" | 2024-01-22 | 44 Upvotes 19 Comments
π Mitochondrial Eve
In human genetics, the Mitochondrial Eve (more technically known as the Mitochondrial-Most Recent Common Ancestor, shortened to mt-Eve or mt-MRCA) is the matrilineal most recent common ancestor (MRCA) of all living humans. In other words, she is defined as the most recent woman from whom all living humans descend in an unbroken line purely through their mothers and through the mothers of those mothers, back until all lines converge on one woman.
In terms of mitochondrial haplogroups, the mt-MRCA is situated at the divergence of macro-haplogroup L into L0 and L1β6. As of 2013, estimates on the age of this split ranged at around 155,000 years ago, consistent with a date later than the speciation of Homo sapiens but earlier than the recent out-of-Africa dispersal.
The male analog to the "Mitochondrial Eve" is the "Y-chromosomal Adam" (or Y-MRCA), the individual from whom all living humans are patrilineally descended. As the identity of both matrilineal and patrilineal MRCAs is dependent on genealogical history (pedigree collapse), they need not have lived at the same time. As of 2015, estimates of the age of the Y-MRCA range around 200,000 to 300,000 years ago, roughly consistent with the emergence of anatomically modern humans.
The name "Mitochondrial Eve" alludes to the biblical Eve, which has led to repeated misrepresentations or misconceptions in journalistic accounts on the topic. Popular science presentations of the topic usually point out such possible misconceptions by emphasizing the fact that the position of mt-MRCA is neither fixed in time (as the position of mt-MRCA moves forward in time as mitochondrial DNA (mtDNA) lineages become extinct), nor does it refer to a "first woman", nor the only living female of her time, nor the first member of a "new species".
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- "Mitochondrial Eve" | 2024-07-22 | 25 Upvotes 6 Comments
π Bioluminescence
Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria, and terrestrial arthropods such as fireflies. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves.
In a general sense, the principal chemical reaction in bioluminescence involves a light-emitting molecule and an enzyme, generally called luciferin and luciferase, respectively. Because these are generic names, luciferins and luciferases are often distinguished by the species or group, e.g. firefly luciferin. In all characterized cases, the enzyme catalyzes the oxidation of the luciferin.
In some species, the luciferase requires other cofactors, such as calcium or magnesium ions, and sometimes also the energy-carrying molecule adenosine triphosphate (ATP). In evolution, luciferins vary little: one in particular, coelenterazine, is found in 11 different animal phyla, though in some of these, the animals obtain it through their diet. Conversely, luciferases vary widely between different species, which is evidence that bioluminescence has arisen over 40 times in evolutionary history.
Both Aristotle and Pliny the Elder mentioned that damp wood sometimes gives off a glow. Many centuries later Robert Boyle showed that oxygen was involved in the process, in both wood and glowworms. It was not until the late nineteenth century that bioluminescence was properly investigated. The phenomenon is widely distributed among animal groups, especially in marine environments. On land it occurs in fungi, bacteria and some groups of invertebrates, including insects.
The uses of bioluminescence by animals include counterillumination camouflage, mimicry of other animals, for example to lure prey, and signaling to other individuals of the same species, such as to attract mates. In the laboratory, luciferase-based systems are used in genetic engineering and biomedical research. Researchers are also investigating the possibility of using bioluminescent systems for street and decorative lighting, and a bioluminescent plant has been created.
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- "Bioluminescence" | 2022-06-12 | 13 Upvotes 8 Comments
π Miraculin
Miraculin is a taste modifier, a glycoprotein extracted from the fruit of Synsepalum dulcificum. The berry, also known as the miracle fruit, was documented by explorer Chevalier des Marchais, who searched for many different fruits during a 1725 excursion to its native West Africa.
Miraculin itself does not taste sweet. When taste buds are exposed to miraculin, the protein binds to the sweetness receptors. This causes normally sour-tasting acidic foods, such as citrus, to be perceived as sweet. The effect can last for one or two hours.
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- "Miraculin" | 2023-05-06 | 13 Upvotes 5 Comments
π Folding@Home
Folding@home (FAH or F@h) is a distributed computing project aimed to help scientists develop new therapeutics for a variety of diseases by the means of simulating protein dynamics. This includes the process of protein folding and the movements of proteins, and is reliant on simulations run on volunteers' personal computers. Folding@home is currently based at the University of Pennsylvania and led by Greg Bowman, a former student of Vijay Pande.
The project utilizes graphics processing units (GPUs), central processing units (CPUs), and ARM processors like those on the Raspberry Pi for distributed computing and scientific research. The project uses statistical simulation methodology that is a paradigm shift from traditional computing methods. As part of the clientβserver model network architecture, the volunteered machines each receive pieces of a simulation (work units), complete them, and return them to the project's database servers, where the units are compiled into an overall simulation. Volunteers can track their contributions on the Folding@home website, which makes volunteers' participation competitive and encourages long-term involvement.
Folding@home is one of the world's fastest computing systems. With heightened interest in the project as a result of the COVID-19 pandemic, the system achieved a speed of approximately 1.22 exaflops by late March 2020 and reached 2.43 exaflops by April 12, 2020, making it the world's first exaflop computing system. This level of performance from its large-scale computing network has allowed researchers to run computationally costly atomic-level simulations of protein folding thousands of times longer than formerly achieved. Since its launch on OctoberΒ 1, 2000, Folding@home was involved in the production of 226 scientific research papers. Results from the project's simulations agree well with experiments.
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- "Folding@Home" | 2024-03-16 | 10 Upvotes 5 Comments