Mutagenesis is a process by which the genetic information of an organism is changed, resulting in a mutation. It may occur spontaneously as a result of exposure to mutagens, it can be achieved experimentally using laboratory procedures. In nature mutagenesis can lead to cancer and various heritable diseases, but it is a driving force of evolution. Mutagenesis as a science was developed based on work done by Hermann Muller, Charlotte Auerbach and J. M. Robson in the first half of the 20th century. DNA may be modified, either or artificially, by a number of physical and biological agents, resulting in mutations. Hermann Muller found that "High temperatures" have the ability to mutate genes in the early 1920s, in 1927, demonstrated a causal link to mutation upon experimenting with an x-ray machine and noting phylogenetic changes when irradiating fruit flies with high dose of X-rays. Muller observed a number of chromosome rearrangements in his experiments, suggested mutation as a cause of cancer.
The association of exposure to radiation and cancer had been observed as early as 1902, six years after the discovery of X-ray by Wilhelm Röntgen and radioactivity by Henri Becquerel. Muller's contemporary Lewis Stadler showed the mutational effect of X-ray on barley in 1928, ultraviolet radiation on maize in 1936. In 1940s, Charlotte Auerbach and J. M. Robson, found that mustard gas can cause mutations in fruit flies. While changes to the chromosome caused by X-ray and mustard gas were observable to the early researchers, other changes to the DNA induced by other mutagens were not so observable, the mechanism may be complex and takes longer to unravel. For example, soot was suggested to be a cause of cancer as early as 1775, coal tar was demonstrated to cause cancer in 1915; the chemicals involved in both were shown to be polycyclic aromatic hydrocarbons. PAHs by themselves are not carcinogenic, it was proposed in 1950 that the carcinogenic forms of PAHs are the oxides produced as metabolites from cellular processes.
The metabolic process was identified in 1960s as catalysis by cytochrome P450 which produces reactive species that can interact with the DNA to form adducts,. Mammalian nuclear DNA may sustain more than 60,000 damage episodes per cell per day, as listed with references in DNA damage. If left uncorrected, these adducts, after misreplication past the damaged sites, can give rise to mutations. In nature, the mutations that arise may be beneficial or deleterious—this is the driving force of evolution. An organism may acquire new traits through genetic mutation, but mutation may result in impaired function of the genes, in severe cases, cause the death of the organism. Mutation is a major source for acquisition of resistance to antibiotics in bacteria and to antifungal agents in yeasts. In the laboratory, mutagenesis is a useful technique for generating mutations that allows the functions of genes and gene products to be examined in detail, producing proteins with improved characteristics or novel functions, as well as mutant strains with useful properties.
The ability of radiation and chemical mutagens to cause mutation was exploited to generate random mutations, but techniques were developed to introduce specific mutations. Humans on average pass 60 new mutations to their children but fathers pass more mutations depending on their age, transmitting an average of two new mutations with every additional year of their age to the child. DNA damage is an abnormal alteration in the structure of DNA that cannot, itself, be replicated when DNA replicates. In contrast, a mutation is a change in the nucleic acid sequence. Damage can occur from chemical addition, or structural disruption to a base of DNA, or a break in one or both DNA strands; such DNA damage may result in mutation. When DNA containing damage is replicated, an incorrect base may be inserted in the new complementary strand as it is being synthesized; the incorrect insertion in the new strand will occur opposite the damaged site in the template strand, this incorrect insertion can become a mutation in the next round of replication.
Furthermore, double-strand breaks in DNA may be repaired by an inaccurate repair process, non-homologous end joining, which produces mutations. Mutations can ordinarily be avoided if accurate DNA repair systems recognize DNA damage and repair it prior to completion of the next round of replication. At least 169 enzymes are either directly employed in DNA influence DNA repair processes. Of these, 83 are directly employed in the 5 types of DNA repair processes indicated in the chart shown in the article DNA repair. Mutagenesis may occur endogenously, for example, through spontaneous hydrolysis, or through normal cellular processes that can generate reactive oxygen species and DNA adducts, or through error in replication and repair. Mutagenesis may arise as a result of the presence of environmental mutagens that induce changes to the DNA; the mechanism by which mutation arises varies according to the causative agent, the mutagen, involved. Most mutagens act either directly, or indirectly via mutagenic metabolites, on the DNA producing lesions.
Some, may affect the replication or chromosomal partition mechanism, other cellular processes. Mutagenesis may be self-induced by unicellular organisms when environmental conditions are rest
The H Line, part of the light rail system operated by the Regional Transportation District in the Denver-Aurora Metropolitan Area in Colorado, was added to the system on November 17, 2006, with the completion of the Southeast Corridor project. It is one of four routes; the line was extended to reach Florida station on February 24, 2017 along with the opening of the R line. According to a map in the RTD's service plan for the corridor, the H Line's color is blue. From the start of each day, the H Line begins its service southbound at Evans station to Florida Station. At the end of the service, the H Line terminates its service at Broadway station; the H Line's northern terminus is at California in downtown Denver. It shares track with the L Line in Downtown Denver and the D Line and F Line until it reaches I-25 & Broadway station follows the Southeast Corridor to a junction past Southmoor Station, follows the I-225 branch of the system to Southeast terminus at Florida station in Aurora; the 2004 voter-approved FasTracks initiative extended the H Line 3.5 mi to the north along Interstate 225 with stops at Iliff Avenue and Florida Avenue.
Work began in 2012, the two station extension was combined with I-225 corridor light-rail line in 2013. Construction was long expected to be completed in 2016, however opening was delayed until February 24, 2017. RTD H Line Schedule
Siu Hong is an MTR station located beside Siu Hong Court, Tuen Mun, New Territories. It is built on the Tuen Mun Nullah east of Siu Hong Court; the station is on the West Rail Line between Tin Shui Tuen Mun stations. Elevated public transport interchanges are provided at both the south and north ends of the station. Two access ramps link the public transport interchanges to Castle Peak Road and Tsing Lun Road for access to feeder services such as buses and taxis. Construction started in July 1999 with the award of civil contract CC-212 for the West Rail Line station to HK ACE JV at a contract sum of HK$1,386 million; the topping-out was marked on 26 February 2002 by KCR chairman Michael Tien and transport legislator Miriam Lau. It was opened to the public on 20 December 2003 with the commencement of West Rail service; the elevated station is located above the Tuen Mun Nullah. To support the station, 352 columns were built in the river bed; as a result, the river was widened by about 17 metres along the length of the station to maintain its drainage capacity.
Platforms 1 and 2 share the same island platform. The first train to Tuen Mun departs at 6:26 a.m. while the last train departs at 12:40 a.m. the day after. The first train to Hung Hom departs at 5:47 a.m. while the last train departs at 12:17 a.m. the day after. A: Brilliant Garden B1: Light Rail Platform 2 B2: Light Rail Platform 2 C1: Light Rail Platforms 1 and 5 C2: Light Rail Platform 6 C3: Light Rail Platforms 1 and 5 D: Lost Property & Travel Scheme Office E: San Hing Tsuen F: Lingnan University BusesMTR Bus K51: Fu Tai – Tai Lam K58: Fu Tai – Castle Peak Bay Kowloon Motor Bus 261: Sam Shing – Tin Ping Long Win Bus E33P: Siu Hong Station - Hong Kong International AirportPublic light busNew Territories Green Minibus 42: Tsz Tin Tsuen – Tuen Mun Town Centre 46: Fu Tai – Tuen Mun Town Centre
David Palladini was an American illustrator, best known for his Aquarian Tarot deck and its reworking as the New Palladini Tarot, illustrations of children's books The Girl Who Cried Flowers and other tales by Jane Yolen. His style is reminiscent of the Art Nouveau illustrations of Alfons Mucha and Aubrey Beardsley, the Art Deco designs of Erte. Palladini emigrated to America as a child, his dual cultural background is expressed in the lush creativity of his work. After studying art and film at the Pratt Institute in New York City, he was a photographer at the 1968 Summer Olympic Games in Mexico City on his first job. Palladini illustrated the second edition of a novel by The Eyes of the Dragon; the artwork was rendered in ink on Bienfeng velour paper. Depending on retention of the illustrations subsequently, that may be his most held work in WorldCat libraries. Otherwise Yolen's The Girl Who Cried Flowers is his most held, by a wide margin, he did an edition of Beauty: A Retelling of the Story of Beauty and the Beast by Robin McKinley, her first novel.
David's artistic memoir, The Journal of an Artist, a bracingly honest look at a man who chose to honor his authentic path by devoting his life to art, was published by Black Swan Press in 2011. David discusses his work on The Aquarian Tarot and the New Palladini Tarot in Painting the Soul: The Tarot Art of David Palladini, with co-author Anastasia Haysler published by Black Swan Press in 2013. David has worked and lived in The Hamptons and France, he spent the last years of his life in Newport Beach and continued to paint and exhibit his work. David died on March 2019, peacefully at home. David Palladini at Library of Congress Authorities — with 12 catalog records David Palladini Official Website
Joseph Frye was a renowned military leader from colonial Maine. Born in Andover, Massachusetts, he obtained the rank of general in the Massachusetts militia after serving in King George's War and the French and Indian War. During the latter conflict, under the command of Edward Winslow, Frye helped build Fort Halifax in present-day Maine and participated in the Battle of Fort Beauséjour and the Battle of Petitcodiac, he was commander at Fort Gaspareaux. He was present on Lake George in August 1757 at the Siege of Fort William Henry, he returned to Nova Scotia and took command of Fort Cumberland. For services during that conflict, the Massachusetts General Court in 1762 granted him a township on the Saco River which had once been the Sokokis Abenaki village of Pequawket. In 1777, the plantation was incorporated as Fryeburg, named in his honor. Frye is best known for the role he played expanding the colonial frontier into lands held by both the French and Abenakis, he is regarded as the successor of John Lovewell, an enemy of Molly Ockett and sage among dispossessed Algonquian peoples.
Frye served in the early stages of the American Revolutionary War, first as a major general of Massachusetts militia, briefly as a brigadier general in the Continental Army. He resigned on 23 April 1776. Joseph Frye married Mehitable sometime before the birth of Joseph Jr on 17 July 1733. Samuel followed in 1735, Mehitable in April 1738, who died young, was replaced by another Mehitable in May 1739, who died within the month. Mehitable Frye was born in April 1741. In the interim, Joseph Jr died and was replaced by another in July 1743. Tabitha followed in 1744, next Hannah in 1748. Richard was born in 1751 to the Captain, Nathaniel in 1753. In the meantime, Samuel had expired and was replaced by another in 1758, this one born to the Colonel, he is the namesake of Frye Island and the aforementioned Fryeburg, Maine. Joseph Frye: Maine Proprietor and Soldier Collections of the Maine Historical Society By Maine Historical Society
Arun Mitra was a Bengali poet. English translations of titles are literal in most instances. Transcription of Bengali titles try to represent, as much as possible, the Bengali vernacular and not Sanskrit pronunciation of words. Prantorekha Arani Publication, Kolkata. 1943 Utser Dikey Dipankar Publication, Kolkata. 1955 Ghonishto Taap Tribeni Publishers, Kolkata. 1963 Mancher Bairey Matitey Saraswat Publication, Kolkata. 1970 Shudhu Raater Shabdo Noi Nabopatro Publication, Kolkata. 1978 Prathom Poli Shesh Pathor Karuna Publication, Kolkata. 1981 Khunjtey Khunjtey Eto Door Pratikhshan Publication, Kolkata. 1986 Jodio Agun Jhor Dhasha Danga Pratikhshan Publication, Kolkata. 1988 Ei Amrito Ei Garol Proma Publication, Kolkata. 1991 Tunikathaar Gherao Thekey Bolchhi Anushtup Publication, Kolkata. 1992 Khara Urboray Chinho Diye Choli Pratikhshan Publication, Kolkata. 1994 Andhokaar Jatokkhon Jegey Thakey Ananda Publishers, Kolkata. 1996 Ora Uritey Noi Kobita Pakhshik, Kolkata. 1997 Bhangoner Mati Dey's Publishing House, Kolkata.
1998 Uchchhanno Shomayer Shukh Dukkho Ghirey Ananda Publishers, Kolkata. 1999 Arun Mitrer Sreshtho Kobita Bharobi Publication, Kolkata. 1972 Arun Mitrer Sreshtho Kobita Narbaak Publication, Kolkata. 1985 Kabya Shamagro, Vol. I Protibhas Kolkata. 1988 Kabya Shamagro, Vol. II Protibhas Publication, Kolkata. 1992 Bulaar Raagmala Proma Publication, Kolkata. 1994 Nirbachito Premer Kobita Bikash Gronthaboli, Kolkata. 1994 Panchsho Bachhorer Pharashi Kobita Translation of various French poets Proma Publication, Kolkata. 1994 Shwanirbachito Sreshtho Kobita Abhijat Publication, Kolkata. 1999 Arun Mitrer Sreshtho Kobita Dey's Publishing House, Kolkata. 1999 Arun Mitrer Anubad Sangraha, Vol I Ed. Chinmoy Guha, Kolkata. 2012 ISBN 978-93-81346-24-2. Arun Mitrer Prabandha Sangraha, Vol I Ed. Chinmoy Guha, Kolkata. 2012. ISBN 978-93-81346-49-5. Shikawr Jodi Chena Jai Bengali novel, Karuna Publication, Kolkata. 1979 Candide, Ba Ashabad Translation of Voltaire, Sahitya Akademi, New Delhi. 1970, 3rd Edition 2001 Pharashi Shahitto Proshongey Critical essays Proma Publication, Kolkata.
1985 Srijan Shahitto Nanaan Bhabna Protibhas Publication, Kolkata. 1987 Aragon On Louis Aragon: Critical/Biographical Proma Publication, Kolkata. 1991 Khola Chokhey Proma Publication, Kolkata. 1992 Pather Morey Remembering writers, friends Proma Publication, Kolkata. 1996 Kobir Katha, Kobider Katha Essays on poetry and individual poets Kolkata. 1997 Kobita Ami O Amra Essays on Bengali and French literature Dey's Publishing House, Kolkata. 1999 Jibaner Rangey Memoirs Abhijit Publication, Kolkata. 1999 Kobi Arun Mitra Collection of critical essays, commentaries edited by Shankha Ghosh and Arun Sen Parichay/Anushtup, Kolkata. 1986 Arun Mitra by Abanti Sanyal "Makers of Indian Literature" series Sahitya Akademi, New Delhi. 2003 arunmitra.org: Website launched on centenary of Arun Mitra Some writings of Arun Mitra Nirmal Kanti Bhattacharjee: An Overview - MUSE India