WordNet

not arising from natural growth or characterized by vital processes
artificially formal; "that artificial humility that her husband hated"; "contrived coyness"; "a stilted letter of acknowledgment"; "when people try to correct their speech they develop a stilted pronunciation" (同)contrived, hokey, stilted
contrived by art rather than nature; "artificial flowers"; "artificial flavoring"; "an artificial diamond"; "artificial fibers"; "artificial sweeteners" (同)unreal
a commercial leavening agent containing yeast cells; used to raise the dough in making bread and for fermenting beer or whiskey (同)barm
any of various single-celled fungi that reproduce asexually by budding or division
not only so, but; "I therein do rejoice, yea, and will rejoice" (同)yeah
an affirmative; "The yeas have it"
a threadlike strand of DNA in the cell nucleus that carries the genes in a linear order; "humans have 22 chromosome pairs plus two sex chromosomes"

PrepTutorEJDIC

『人造の』,『人工の』,人為的な / 模造の / 不自然な,見せかけの
イースト,酵母(パン種・ビール醸造用などに使う)
はい,さよう,しかり / 全く,実に,げに / 賛成,背定,賛成の返事,賛成投票[者]
染色体

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/09/26 21:41:18」(JST)

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This is a photo of two copies of the Washington University Human Genome YAC Library. Each of the stacks is approximately 12 microtiter plates. Each plate has 96 wells, each with different yeast clones.

A yeast artificial chromosome (YAC) is a vector used to clone DNA fragments larger than 100 kb and up to 3000 kb. YACs are useful for the physical mapping of complex genomes and for the cloning of large genes. First described in 1983 by Murray and Szostak, a YAC is an artificially constructed chromosome that contains a centromere, telomeres and an autonomous replicating sequence (ARS) element, which are required for replication and preservation of YAC in yeast cells. ARS elements are thought to act as replication origins. A YAC is built using an initial circular plasmid, which is typically broken into two linear molecules using restriction enzymes; DNA ligase is then used to ligate a sequence or gene of interest between the two linear molecules, forming a single large linear piece of DNA.^{[citation needed]}.

A plasmid-derived origin of replication (ori) and an antibiotic resistance gene allow the YAC vector to be amplified and selected for in E.coli. TRP1 and URA3 genes are included in the YAC vector to provide a selection system for identifying transformed yeast cells that include YAC by complementing recessive alleles trp1 and ura3 in yeast host cell. YAC vector cloning site for foreign DNA is located within the SUP4 gene. This gene compensates for a mutation in the yeast host cell that causes the accumulation of red pigment. The host cells are normally red, and those transformed with YAC only, will form colourless colonies. Cloning of a foreign DNA fragment into the YAC causes insertional inactivation, restoring the red colour. Therefore the colonies that contain the foreign DNA fragment are red. ^[1]

Advantages and Disadvantages

Yeast expression vectors, such as YACs, YIps (yeast integrating plasmids), and YEps (yeast episomal plasmids), have an advantage over bacterial artificial chromosomes (BACs) in that they can be used to express eukaryotic proteins that require posttranslational modification.

However, YACs are significantly less stable than BACs, producing "chimeric effects": artifacts where the sequence of the cloned DNA actually corresponds not to a single genomic region but to multiple regions. Chimerism may be due to either co-ligation of multiple genomic segments into a single YAC, or recombination of two or more YACs transformed in the same host Yeast cell. ^[2] The incidence of chimerism may be as high as 50%. ^[3]. Other artifacts are deletion of segments from a cloned region, and rearrangement of genomic segments (such as inversion). In all these cases, the sequence as determined from the YAC clone is different from the original, natural sequence, leading to inconsistent results and errors in interpretation if the clone's information is relied upon. Due to these issues, the Human Genome Project ultimately abandoned the use of YACs and switched to bacterial artificial chromosomes, where the incidence of these artifacts is very low.

References

^ Strachan T. (2011). Human molecular genetics / Tom Strachan and Andrew Read, 4th ed.
^ Haldi M, Perrot V, Saumier M, Desai T, Cohen D, Cherif D, Ward D, Lander ES. Large human YACs constructed in a rad52 strain show a reduced rate of chimerism. Genomics. 1994 Dec;24(3):478-84.
^ Bronson SK, Pei J, Taillon-Miller P, Chorney MJ, Geraghty DE, Chaplin DD.Isolation and characterization of yeast artificial chromosome clones linking the HLA-B and HLA-C loci.Proc Natl Acad Sci U S A. 1991 Mar 1;88(5):1676-80.

External links

Yeast+Artificial+Chromosomes at the US National Library of Medicine Medical Subject Headings (MeSH)

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English Journal

Dantrolene is neuroprotective in Huntingtons disease transgenic mouse model.

Chen X, Wu J, Lvovskaya S, Herndon E, Supnet C, Bezprozvanny I.AbstractABSTRACT:
Molecular neurodegeneration.Mol Neurodegener.2011 Nov 25;6(1):81. [Epub ahead of print]
ABSTRACT:BACKGROUND: Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a polyglutamine expansion in the Huntingtin protein which results in the selective degeneration of striatal medium spiny neurons (MSNs). Our group has previously demonstrated that calcium (Ca2+) sign
PMID 22118545

Endogenous transcription at the centromere facilitates centromere activity in budding yeast.

Ohkuni K, Kitagawa K.SourceCenter for Childhood Cancer, The Research Institute, Nationwide Children's Hospital, Columbus, OH 43205, USA.
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PMID 22000103

Japanese Journal

Protection of isolated chromosome using bioactive beads toward physical and chemical stresses

Murakawa Tomoko,Hayashihara Kayoko,Ito Kohichi,Doi Tomoyuki,Kajiyama Shin'ichiro,Fukui Kiichi
Chromosome
… Moreover, yeast artificial chromosomes (YACs) have been introduced into yeast and tobacco cells and transformants were successfully obtained. … Chromosome entrapped bioactive beads were spherical and up to 90-100% encapsulation efficiency could be achieved when the concentration of the chromosomes to be mixed with sodium alginate solution was adjusted to 1×10^8/ml. …
NAID 110006873786

染色体異常分配挙動を示すYACクローンの特性解析(保健福祉学部栄養学科)

甲斐達男,尾上均,南里宏樹,竜口和惠
西南女学院大学紀要 10, 75-82, 2006-02-28
我々が先に構築したヒト21番染色体特異的なゲノムライブラリーの中から、ユニークなクローンが新たに発見された。このYAC(酵母人工染色体)クローンは前報とは違った異常な染色体挙動を示した。このクローンはCHEFによる核型分析では人工染色体と思われる特別なバンドは示さなかったが、ヒト特有の短鎖反復配列であるAluが二つのバンド(200kbと125kb)にハイブリダイズした。一般にはひとつの酵母細胞に複 …
NAID 110004866391

Related Pictures

★リンクテーブル★

リンク元	「酵母人工染色体」「酵母人工染色体ベクター」
拡張検索	「yeast artificial chromosome vector」
関連記事	「artificial」