WordNet

to remain unmolested, undisturbed, or uninterrupted -- used only in infinitive form; "let her be"
work in a specific place, with a specific subject, or in a specific function; "He is a herpetologist"; "She is our resident philosopher" (同)follow
have life, be alive; "Our great leader is no more"; "My grandfather lived until the end of war" (同)live
be identical to; be someone or something; "The president of the company is John Smith"; "This is my house"
happen, occur, take place; "I lost my wallet; this was during the visit to my parents house"; "There were two hundred people at his funeral"; "There was a lot of noise in the kitchen"
have the quality of being; (copula, used with an adjective or a predicate noun); "John is rich"; "This is not a good answer"
occupy a certain position or area; be somewhere; "Where is my umbrella?" "The toolshed is in the back"; "What is behind this behavior?"
spend or use time; "I may be an hour"
stake on the outcome of an issue; "I bet $100 on that new horse"; "She played all her money on the dark horse" (同)wager, play
the act of gambling; "he did it on a bet" (同)wager
maintain with or as if with a bet; "I bet she will be there!" (同)wager
second in order of importance; "the candidate, considered a beta male, was perceived to be unable to lead his party to victory"
the 2nd letter of the Greek alphabet
preliminary or testing stage of a software or hardware product; "a beta version"; "beta software"
a fibrous scleroprotein that occurs in the outer layer of the skin and in horny tissues such as hair, feathers, nails, and hooves (同)ceratin
beets (同)genus Beta

PrepTutorEJDIC

《連結語として補語を伴なって…『である』,…だ,…です / 《位置・場所を表す語句を伴って》(…に)『ある』,いる(occupy a place or situation) / 〈物事が〉『存在する』,ある(exist);〈生物が〉生存する,生きている(live) / 行われる,起こる,発生する(take place, occur) / 存続する,そのままでいる(remain as before) / 《『be to』 do》 / …する予定である,…することになっている / …すべきだ / 《受動態の不定詞を伴って》…できる / 《命令》…するのだ / 《条件節に》…する意図がある / 《『if…were to』 do》…するとしたなら / 《『be』 do『ing』》《進行形》 / 《進行中の動作》…している,しつつある / 《近い未来》…しようとしている,するつもり / 《動作の反復》(いつも)…している / 《『be』+『他動詞の過去分詞』》《受動態》…される,されている / 《『be』+『自動詞の過去分詞』》《完了形》…した[状態にある]
『かけ』・(…との)かけ《+『with』+『名』》 / かけた物(金) / かけの対象 / 〈金・物〉'を'『かける』 / (かけ事・ゲームなどで)〈人〉‘と'『かけをする』《+『名』〈人〉+『on』+『名』》 / (…に)『かける』《+『on』(『against』)+『名』(one's do『ing』)》
ベータ(ギリシア語アルファベットの第2文字;B,β;英語のB,b に遭当)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/03/04 20:14:56」(JST)

wiki en

β-keratin or beta-keratin (not to be confused with β-carotene) is rich in stacked β pleated sheets, in contrast to alpha-keratin, a fibrous protein rich in alpha helices.

β-keratin is found in reptiles.^[1]^[2] It adds much more rigidity to reptilian skin than alpha-keratin does to mammalian skin.

β-keratin is impregnated into the stratum corneum of the reptilian skin, providing waterproofing and the prevention of desiccation.

In birds, scales, beaks, claws and feathers also contain β-keratin of the avian family. Phylogenetic studies of β-keratin sequences show that feather β-keratins evolved from scale β-keratins.^[3] The scale β-keratins form the basal group in avians. Duplication and divergence events then led to claw β-keratin genes, and further recombination resulted in new feather and feather-like avian β-keratin genes. Evidence for these duplication events comes from the correlation of feather β-keratin clade structure with their genomic loci.^[4]

Changes in β-keratins may have also influenced the development of powered flight. A recent study using molecular dating methods to link the evolution of β-keratin genes to that of feathers reveals that the avian β-keratin family began diverging from the crocodile family about 216 million years ago.^[4] But the feather β-keratin family did not begin diverging until 125 million years ago, a date consistent with the adaptive radiation of birds during the Cretaceous. β-keratins found in modern feathers have increased elasticity, a factor that may have contributed to their role in flight.^[4] Thus, the feathered ancestors of birds including Anchoirnis and Archaeopteryx, whose flight capabilities have been questioned,^[5] would have had avian, but not feather β-keratins.

The small alvarezsaurid dinosaur Shuvuuia deserti showed evidence of a featherlike skin covering. Analysis by Schweitzer et al. (1999) showed that these featherlike structures consisted of beta-keratin.^[6]

References

^ Dalla Valle L, Nardi A, Belvedere P, Toni M, Alibardi L (July 2007). "Beta-keratins of differentiating epidermis of snake comprise glycine-proline-serine-rich proteins with an avian-like gene organization". Dev. Dyn. 236 (7): 1939–53. doi:10.1002/dvdy.21202. PMID 17576619.
^ Dalla Valle L, Nardi A, Toffolo V, Niero C, Toni M, Alibardi L (February 2007). "Cloning and characterization of scale beta-keratins in the differentiating epidermis of geckoes show they are glycine-proline-serine-rich proteins with a central motif homologous to avian beta-keratins". Dev. Dyn. 236 (2): 374–88. doi:10.1002/dvdy.21022. PMID 17191254.
^ Greenwold, M.J.; Sawyer, R.H. (2010). "Genomic organization and molecular phylogenies of the beta (β) keratin multigene family in the chicken (Gallus gallus) and zebra finch (Taeniopygia guttata): implications for feather evolution". BMC Evolutionary Biology 10. doi:10.1186/1471-2148-10-148.
^ ^a ^b ^c Greenwold, M.J.; Sawyer, R.H. (2011). "Linking the molecular evolution of avian beta (β) keratins to the evolution of feathers". Journel of Experimental Zoology 316B. doi:10.1002/jez.b.21436.
^ Nudds, R.L.; Dyke, G.J. (14). "Narrow Primary Feather Rachises in Confuciusornis and Archaeopteryx Suggest Poor Flight Ability". Science 328: 887–889. doi:10.1126/science.1188895.
^ .Schweitzer, Mary Higby, Watt, J.A., Avci, R., Knapp, L., Chiappe, L, Norell, Mark A., Marshall, M. (1999). "Beta-Keratin Specific Immunological reactivity in Feather-Like Structures of the Cretaceous Alvarezsaurid, Shuvuuia deserti Journal of Experimental Biology (Mol Dev Evol) 255:146-157

External links

beta-Keratins at the US National Library of Medicine Medical Subject Headings (MeSH)

There are two main forms of keratin, alpha-keratin and beta-keratin. Alpha-keratin is seen in humans and other mammals, beta-keratin is present in birds and reptiles. Beta-keratin is harder than alpha-keratin. Structurally alpha-keratin have alpha-helical coiled coil structure while beta-keratin have twisted beta sheet structure.bIn the case of β-sheets, this allows sterically-unhindered hydrogen bonding between the amino and carboxyl groups of peptide bonds on adjacent protein chains, facilitating their close alignment and strong binding. Fibrous keratin molecules can twist around each other to form helical intermediate filaments.

SILK:- The secondary structure of silk is an example of the beta pleated sheet. In this structure, individual protein chains are aligned side-by-side with every other protein chain aligned in an opposite direction.The chains are antiparallel, with an alternating C → N orientation. The protein chains are held together by intermolecular hydrogen bonding, that is hydrogen bonding between amide groups of two separate chains. This intermolecular hydrogen bonding in the beta-pleated sheet is in contrast to the intramolecular hydrogen bonding in the alpha-helix.

The hydrogen on the amide of one protein chain is hydrogen bonded to the amide oxygen of the neighboring protein chain. The pleated sheet effect arises form the fact that the amide structure is planar while the "bends" occur at the carbon containing the side chain.

Fortunately, the "side" chain R groups in silk are not very bulky. The basic primary structure of silk consists of a six amino acid unit that repeats itself. The sequence where every other unit is glycine in silk is: -gly-ala-gly-ala-gly-ala-. Although glycine and alanine make up 75-80% of the amino acids in silk, another 10-15% is serine and the final 10% contain bulky side chains such as in tyr, arg, val, asp, and glu.

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English Journal

Molecular evolution and expression of archosaurian β-keratins: Diversification and expansion of archosaurian β-keratins and the origin of feather β-keratins.

Greenwold MJ, Sawyer RH.SourceDepartment of Biological Sciences, University of South Carolina, Columbia, South Carolina.
Journal of experimental zoology. Part B, Molecular and developmental evolution.J Exp Zool B Mol Dev Evol.2013 Sep;320(6):393-405. doi: 10.1002/jez.b.22514. Epub 2013 Jun 6.
The archosauria consist of two living groups, crocodilians, and birds. Here we compare the structure, expression, and phylogeny of the beta (β)-keratins in two crocodilian genomes and two avian genomes to gain a better understanding of the evolutionary origin of the feather β-keratins. Unlike squa
PMID 23744807

Stromally Derived Lysyl Oxidase Promotes Metastasis of Transforming Growth Factor-β-Deficient Mouse Mammary Carcinomas.

Pickup MW, Laklai H, Acerbi I, Owens P, Gorska AE, Chytil A, Aakre M, Weaver VM, Moses HL.SourceAuthors' Affiliations: Department of Cancer Biology, Vanderbilt University School of Medicine and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee; and Department of Surgery and Center for Bioengineering and Tissue Regeneration, University of California at San Francisco, San Francisco, California.
Cancer research.Cancer Res.2013 Aug 13. [Epub ahead of print]
The tumor stromal environment can dictate many aspects of tumor progression. A complete understanding of factors driving stromal activation and their role in tumor metastasis is critical to furthering research with the goal of therapeutic intervention. Polyoma middle T-induced mammary carcinomas lac
PMID 23856251

Tissue-engineered mucosa is a suitable model to quantify the acute biological effects of ionizing radiation.

Tra WM, Tuk B, van Neck JW, Hovius SE, Perez-Amodio S.SourceDepartment of Plastic and Reconstructive Surgery, Erasmus MC, Rotterdam, The Netherlands. wendy_tra@hotmail.com
International journal of oral and maxillofacial surgery.Int J Oral Maxillofac Surg.2013 Aug;42(8):939-48. doi: 10.1016/j.ijom.2013.01.025. Epub 2013 Apr 11.
The aim of this study was to evaluate the suitability of tissue-engineered mucosa (TEM) as a model for studying the acute effects of ionizing radiation (IR) on the oral mucosa. TEM and native non-keratinizing oral mucosa (NNOM) were exposed to a single dose of 16.5Gy and harvested at 1, 6, 24, 48, a
PMID 23583647

Japanese Journal

Distribution and Characterization of Keratins in the Epidermis of the Tuatara (Sphenodon punctatus; Lepidosauria, Reptilia)(Morphology)

Alibardi Lorenzo,Toni Mattia
Zoological science 23(9), 801-807, 2006-09-25
… Reptilian scales are mainly composed of alpha- and beta-keratins. … Epidermis and molts from adult individuals of an ancient reptilian species, the tuatara (Sphenodon punctatus), were analysed by immunocytochemistry, mono- and bi-dimensional electrophoresis, and western blotting for alpha- and beta-keratins. … The lack of basic cytokeratins may be due to keratin alteration in molts, following corneification or enzymatic degradation of keratins. …
NAID 110006151764