India Education
Transposons as vector
This is a discussion on Transposons as vector within the Biotechnology Engineering forums, part of the ENGINEERING WORLD category; 1. Ac-Ds Elements The activator (Ac) and dissociation (Ds) elements are simple transposons of maize. It has 4.565 kb long ...
|
|||||||
| Register | FAQ | Members List | Calendar | Search | Today's Posts | Mark Forums Read |
09-11-2008, 05:57 PM
|
||||
|
||||
Transposons as vector
1. Ac-Ds Elements
The activator (Ac) and dissociation (Ds) elements are simple transposons of maize. It has 4.565 kb long autonomous sequence which transcribes 3.5 kb long GC-rich un-translated leader sequence. Four introns are spliced out from the primary transcript and 3.312 nucleotide long mature mRNA is obtained. Consequently 807 amino acids long protein is translated. Within the Ac element the terminal inverted repeats (TIR) of 11 bp are located at both the ends which play a key role in transposition. The protein synthesised by Ac is called transposase which causes transcription of Ac elements (Fig.). The Ds (dissociation) is the defective element of Ac family. Due to deletion, nonautosomal elements are obtained from the autosomal elements. It activates by trans-acting transposase. The 11 bp long TIR is common to all Ds elements. The enzyme transposase cannot be expressed by the Ds element due to deletions. But the transposase that is produced by Ac element is diffused and trans-acting. It causes transposition of Ds elements. By detecting part of the region transposons can be used as vector for cloning a foreign DNA. P Elements:The transposons of Drosophila are known as P elements. The size of different P elements vary. The largest element is 1907 bp long containing 31 bp long terminal inverted repeats at both the ends. The complete elements move autonomously due to expression of transposase enzyme. The other P elements lack internal gene that produce transposase. The terminal and sub-terminal sequences cause transposition in them. A foreign DNA can be inserted into the transposase element to develop recombinant P elements which can be microinjected into the fertilised egg along with normal P element. The normal P supplies transposase to the recombinant P element. Here the non-autonomous element acts as a transformation vector. Consequently the foreign gene inserted into embryonic cell is transposed onto an embryonic chromosome of Drosophila. Gierl et al. (1989) have reviewed the transposable elements of maize. A recombinant P element was prepared by inserting a DNA fragment of a rosy gene (and a marker gene for identification of transgene). It was inserted into a plasmid. Similarly a P element, lacking the ability for integration, was inserted into a plasmid to encode transposase. Both the plasmids were co-injected into the embryo of Drosophila melanogaster mutant in rosy gene. It was found that 50% progeny of D. melanogaster were rosy progeny. This shows the successful transfer of a foreign gene into a cell through P element (Gierl et al., 1989). PLANT AND ANIMAL VIRUSES AS CLONING VECTORS Using gene cloning techniques based on E. coli as host, many eukaryotic genes and their control sequences have been isolated and analysed. Many applications of genetic engineering require vectors for the expression of genes on diverse eukaryotic organisms for engineering of new plants, gene therapy and large scale production of eukaryotic proteins. 1. Plant Viral Vector Plant virus-based vectors can be used for transfer of genes with high efficiency. Because virus genome containing DNA insert cause virsuses infection in host plant and amplified naturally. However, there are many viruses that cause systemic infection. Consequently their genes are introduced into all the cells. Since virus infection results in delivery of a new genetic material into host cells, they provide a natural example of genetic engineer. The DNA insert linked with viral DNA that is present in host cell replicates and expresses in host cell along with viral genes. For insertion of a desired gene into viral genome, it is necessary to study and characterized the virus into detail so that the DNA linked with virus genome may express in the plant. Construction of viral vector that can express in host cell is based on DNA or RNA molecules. Plant virus vectors are nonintegrative. They are transmitted systematically in plant and assembled in host cell in high copy number. But it never integrates with the host genome. Therefore, to act as viral vector, they should: (i) carry extra nucleic acid (DNA or RNA), (ii) have broad host range, (iii) be easily transmitted, and (iv) be preferred to manipulate their genome. There are three groups of viruses (caulimoviruses, geminiviruses and tobamoviruses) which have been worked out in detail for construction of vector. (a) Caulimoviruses: This group includes cauliflower mosaic virus (CaMV) which has extensively been studied. This virus infects mainly the members of Cruciferae. Genome of CaMV is made up of double stranded DNA which was first manipulated by recombinant DNA technology. The CaMV is transmitted naturally simply by rubbing of leaves or by aphids. Viral particles transmitted are isometric, 50 nm in diameter and isolated from inclusion bodies. Viral particles spread rapidly in 3-4 weeks throughout the plant and found at high copy number (about 106 virions per cell). The CaMV DNA remains as linear open circular molecule of 8 kb twisted or knotted forms (Fig). It consists of tightly packed six major and two minor (total I-VIII) open reading frame (ORF) on one coding strand. It replicates through reverse transcription. After infecting the host cell DNA enters inside the nucleus where a supercoiled minichromosome is formed after digestion of a single stranded overhangs and digestion of gaps. Inside the nucleus of plant cell, the minichromosome acts as a template for nuclear RNA polymerase II forming RNA transcripts. Then the transcripts are transported to cytoplasm where it undergoes wither translation or replication into (- ) DNA strand using reverse transcriptase. The (+) DNA strand is synthesised from two primer-binding sites that are present near gaps 2 and 3. The RNA synthesis starts from gap 3' to 5' end of (- ) DNA strand, whereas synthesis started from gap 3 continues to gap 2. Finally, DNA molecules are packed to form viral particles. These particles re-start the similar events after re-entering the cell of a healthy tissue of other plants. The two genomic regions of the virus (ORF I and ORF VII) are non-essential. ORF II synthesises the factors for insect transmission and ORF VII has un-known function. These two regions can be replaced by a foreign DNA and vector constructed. By using this approach, in 1984, Brisson and co-workers transferred CaMV vector containing the bacterial dihydrofolate reductase, into turnip plant cells. This gene expressed into the plants. (b) Geminiviruses: This group consists of single-stranded DNA containing plant viruses that cause diseases in maize cereals, cassava, tomato, Digitaria, Chloris, etc. It has geminated (two paired particles) morphology which differentiate it from the other groups of viruses. The capsids are icosahedral, of 10-20x20 nm dimension enclosing covalently closed one or two circular single-stranded DNA molecule(s) (2.6-3.0 kb). After infection DNA molecule enters in the nucleus. The single stranded DNA is converted into a double-stranded DNA replicative form. Thereafter, many copies of replicative forms of DNA is formed inside the nucleus possibly through 'rolling circle mechanism'. Genome of all group of geminiviruses consists of two elements (i.e. an origin of replication and replication protein), each may become a part of vector. The geminivirus vectors which have been constructed so far consists of reporter or other desired genes, replacing the coat protein expressing sequence of viral genome. These vectors are allowed to insert foreign gene in protoplasts, cultured cells or leaf discs. (iii) Tobamoviruses: One of the important and thoroughly worked out viruses of this group is tobacco mosaic virus (TMV) which consists of RNA as a linear, large, undivided genome. RNA-based vector is constructed by inserting a foreign gene into an intact viral genome. For example TB2 was the first RNA-based RNA vector which was successfully spread in whole plant. TB2 vector was constructed by inserting a foreign gene at the 3' end of the movement protein ORE The nati ve subgenome promoter (sgp) drives the expression of the foreign gene and a sgp from the related virus i.e. ORSV (Odontoglossum ring spot virus) governs the expression of ORF of coat protein. RNA viral vectors containing gene insert can replicate only in protoplast, inoculated leaves or differentiated tissue. Animal Viral Vectors In nature there are several viruses which cause diseases. A virus gets adsorbed to the body surface of suitable host and infects the cell. This ability of animal viruses has been exploited and virusbased vectors have been designed to introduce foreign DNA of known function into cultured eukaryotic cell. In 1979, for the first time a simivian virus 40 (SV 40)- based cloning vector was constructed and used in cloning experiment using mammalian cells. Since then several vectors were constructed using adenovirus, papillomaviruses, retroviruses to clone foreign DNA into the mammalian cells, and baculoviruses in insect cells. In recent years, retrovirus-based vectors are commonly used for gene cloning, because they can infect several types of cells. Since they are single stranded, their high concentrations are required for fully differentiated cells like neurons, hepatocytes, etc. The gag, pol and env genes of retroviruses (which are required for replication and assembly of viral particles) can be replaced with foreign DNA. The recombinant DNA is introduced into mammalian cells in tissue culture.     
|
|
01-07-2011, 12:15 PM
|
|||
|
|||
|
VIAGRA ONLINE BUYING 0.80$ per pill >>> CLICK HERE <<< BUY VIAGRA ONLINE IN USA
VIAGRA ONLINE BUYING $0.80 per pill >>> CLIC HERE <<< BUYING VIAGRA ONLINE no prescription
VIAGRA ONLINE BUYING 0.80$ per pill >>> CLICK HERE <<< VIAGRA ONLINE BUY VIAGRA ONLINE BUY BUY VIAGRA ONLINE pharmacy - BUY VIAGRA ONLINE IN USA BUYING VIAGRA ONLINE legitimate pharmacy VIAGRA ONLINE BUYING $0.80 per pill >>> CLIC HERE <<< BUYING VIAGRA ONLINE CANADA    buy generic viagra Purchase Viagra $1.15 Per Pill | Achat Levitra Eur 1.15 Par Comprime >>> Achat Viagra Cliquez Ici <<< Acheter Viagra 100mg Enligne - Cancer Community Forum buy cheap generic viagra VIAGRA $1.15 per pill BUYING BUY VIAGRA in uk - TheYeogiyo.com BUY VIAGRA ONLINE GENERIC BUYING real VIAGRA ONLINE BUY VIAGRA ONLINE no prescription - BUYING VIAGRA ONLINE BUY VIAGRA ONLINE BRAND BUY cheap VIAGRA ONLINE uk BUY VIAGRA ONLINE IN USA BUY VIAGRA ONLINE CANADA BUY VIAGRA ONLINE without prescription where can i BUY VIAGRA ONLINE BUY VIAGRA ONLINE a href BUY VIAGRA ONLINE BUY real VIAGRA ONLINE BUY VIAGRA ONLINE cheap BUY VIAGRA ONLINE uk BUY VIAGRA ONLINE no prescription cheapest place to BUY VIAGRA ONLINE BUY generic VIAGRA ONLINE BUY VIAGRA ONLINE without a prescription where to BUY ONLINE VIAGRA 100mg pills BUY discount VIAGRA ONLINE BUY VIAGRA ONLINE inu BUY VIAGRA ONLINE pharmacy BUY VIAGRA uk ONLINE best place to BUY VIAGRA ONLINE with no rx BUY VIAGRA ONLINE canada BUY VIAGRA ONLINE legitimate pharmacy VIAGRA ONLINE BUY BUYING VIAGRA ONLINE GENERIC BUYING VIAGRA ONLINE BRAND BUYING cheap VIAGRA ONLINE uk BUYING VIAGRA ONLINE IN USA BUYING VIAGRA ONLINE CANADA BUYING VIAGRA ONLINE without prescription where can i BUYING VIAGRA ONLINE BUYING VIAGRA ONLINE a href BUYING VIAGRA ONLINE BUYING real VIAGRA ONLINE BUYING VIAGRA ONLINE cheap BUYING VIAGRA ONLINE uk BUYING VIAGRA ONLINE no prescription cheapest place to BUYING VIAGRA ONLINE BUYING generic VIAGRA ONLINE BUYING VIAGRA ONLINE without a prescription where to BUYING ONLINE VIAGRA 100mg pills BUYING discount VIAGRA ONLINE BUYING VIAGRA ONLINE inu BUYING VIAGRA ONLINE pharmacy BUYING VIAGRA uk ONLINE best place to BUYING VIAGRA ONLINE with no rx BUYING VIAGRA ONLINE canada BUYING VIAGRA ONLINE legitimate pharmacy VIAGRA ONLINE BUYING
__________________
best place to BUYING VIAGRA ONLINE with no rx - BUY VIAGRA ONLINE legitimate pharmacy
|
|
01-20-2011, 11:57 PM
|
|||
|
|||
ADOBE PHOTO-SHOP Elements SPANISH FREE DOWNLOAD ADOBE PHOTOSHOP tutorial
    Adobe Photoshop CS + Adobe ImageReady CS for only $69.95 Adobe Photoshop CS3 French - DOWNLOAD NOW $99.95 - DOWNLOAD NOW - ADOBE PHOTOSHOP CS Adobe Photoshop CS2 + Image ready CS2 for only $99.95 - DOWNLOAD NOW Adobe Photoshop CS3 Extended for only $59.95 - DOWNLOAD NOW OnRPG Free MMORPG Forums - View Profile: phottoshop Adobe Photoshop CS3 French - DOWNLOAD NOW $99.95 - DOWNLOAD NOW Adobe Photoshop CS3 German - DOWNLOAD NOW $99.95 - DOWNLOAD NOW Video Games Live Forums - View Profile: NewAdobePremiumCheap Adobe Photoshop CS4 Extended - DOWNLOAD NOW$89.95 - DOWNLOAD NOW Adobe Photoshop CS4 Extended 11.0 German - DOWNLOAD NOW $99.95 - DOWNLOAD NOW Adobe Photoshop CS4 MAC for only $89.95 - DOWNLOAD NOW Adobe Photoshop CS5 Extended for only $129.95 - DOWNLOAD NOW Adobe Photoshop Elements 4.0 for only $39.95 - DOWNLOAD NOW Adobe Photoshop Elements 5 for only $49.95 - DOWNLOAD NOW Adobe Photoshop Elements 7 Espanol for only $49.45 - DOWNLOAD NOW Adobe Photoshop Elements 7 French for only $39.95 - DOWNLOAD NOW Adobe Photoshop Elements 7.0 for only $39.95 - DOWNLOAD NOW Adobe Photoshop Elements 8 for only $39.95 - DOWNLOAD NOW Adobe Photoshop Lightroom 1.3 for only $29.95 - DOWNLOAD NOW Adobe Photoshop Lightroom 1.3 Multilingual for only $39.95 - DOWNLOAD NOW Adobe Photoshop Lightroom 2.1 for only $29.95 - DOWNLOAD NOW Adobe Photoshop Lightroom 2.4 Multilingual for only $49.95 - DOWNLOAD NOW Adobe Photoshop Lightroom 2.5 Multilingual for only $79.00 - DOWNLOAD NOW Adobe Photoshop Lightroom 2.6 Multilingual for only $79.00 - DOWNLOAD NOW
__________________
BUY GENERIC GENERIC CIALIS - low price GENERIC CIALIS BUY
|
|
01-21-2011, 12:01 AM
|
|||
|
|||
|
Free LESB porn galleries - freevideogallery herfirstlesbiansex
Only exclusive pictures movies at lesbian archive! The new site - feminine girl. _ Cached similarlesbians drama video recordings. Erotic xxx sex stories featuring straight gay lesbian and swinger. Hot bbw sex galleries, black and mature chubby asses, fat pussy movies are. Lesbian sex from cute teens discovering it for the first time till hot babes in naughty gang bangs and more. Aspx cachedlesbians in singapore video documentary sgcgojan. Skittlez video shoot lesbians, bisexual women, femmes, studs, dommes, pillow princess. Free hd porn women squirting, sapphic fuck movies lesbian orgies lesbzilla lesbian porn clips only machine sex. Teen lesbian sex video sample lesbian domination lesbian femdom. Watch free lesbian porn videos and lesbian adult movies.
Cachedbreaking kendra wilkinson video details - orgies, lesbians and sex. Lesbian, two lovely lesbians in soft. Twelvefifteen porn videos, teen sex tapes, amateur ex gf porno of lesbian girls fucking, celeb sex tapes, hardcore britney spears porno, free movies and sex. Visit deadly dommes for more dommes. Html cacheddownload sandra shine y sophie moone video lesbians jan. Drumsheugh - lesbian sex row rocked society the school was among the most highly regarded establishments for young ladies, a sanctuary. Sexy chocolate sistas in hot lesbian videos middot; black lesbians licking each other pussies. Information on a place that; a home for a range of organizations and services. Free hot lesbian porn videos free porn vidieos free sixty nine porn. Bisexual picture sex free bisexual porn clip bdsm cartoon sex bisexual porn star bisexual gay lesbian man illinois bisexual woman bisexual free picture sex.
|
|
01-21-2011, 08:42 AM
|
|||
|
|||
|
For all who is interested in it 2 of us dating and uk internet dating site
I will be glad to receive the information on sites on which it is possible to get acquainted in the USA, Canada, Arabian amirates. Sites of international acquaintances interest also. The information on affair dating uk, city dating sex in the city lovers sexinthecity sexy devils co uk and hiv positive dating uk won't prevent
|
|
01-23-2011, 07:15 AM
|
|||
|
|||
|
For all who is interested in it campus dating violence and singles dating with std
If you’re looking for that you have described that look at it:
 This is SITEMAP of this site. Register HERE and chat with other cleveland singles I christian dating free site Web Personals provides Cleveland dating and singles photo ads. Three Keys To Wonderful Dating Experience. Canterbury, Kent, England, United Kingdom, Part of a gallery of color pictures of Europe by professional photographer QT Find here ads for sale, to buy and rent in Canterbury. They maintained that they were simply good friends. Find the Love of your Life or just a Fling ! Ignighter is in the hot seat with Technorati CEO Richard Jalichandra as our Vator Box guest host Welcome to adult online dating. Spring is the time for beginning something recent; dusting yourself down and Seminars, simple tools, practical solutions to you find ideal partner. Passion has many features that you can expect with online such as email access, local dating groups and it even has live webcam capabilities. Oct 2010 Nelly recently called into a Chicago radio station, and denied ever having an official relationship with singer Ashanti. Nov 2008 More superficial, fast encounters - That photo has been included in this blog post - lifeislove. huddy dating interdenominational dating dating violence among college students girls only want boyfriends who have great skills napoleon dynamite dating largest online personals service best dating largest site dating service richardson shellies new boyfriend and i m out of my visual dating free dating service asheville nc radio carbon dating errors diana taurasi boyfriend apostolic christian dating
|
|
01-23-2011, 07:33 AM
|
|||
|
|||
|
взгляд психол
одинокая женщина познакомится с молодым парнем Знакомства майл 24 Персонаж знакомство Знакомства для встречь Знакомства фото девушек и парней Гейзнакомства Лондонские сайты знакомств Секс знакомства рн лайн Телефонный чат знакомств Знакомство ради секса Купавна знакомства знакомства бисексуальные пары. знакомства с состоятельными мужчинами в москве. Добро пожаловать на мой сайт! Тут вы найдете фото и видео по темам: Международные знакомства Гонконг для переписки, гей знакомства для поиска Мусыльманские сайты знакомств Знакомства в питре Знакомство для секса в оленегорске Гей знакомства волгодонск Знакомства для любителей фистинга Знакомство и наб челны Секс чат знакомства киров Би-сексуальные знакомства омск Саранские знакомства Знакомство с директором За деньги и знакомства Знакомства обшение Секс знакомство москва Секс знакомства чернигов Вад знакомства Алейск знакомства Знакомства с богатыми леди Приват знакомств новгород Просмотр фильма знакомтесь дейв Познакомиться с канадцем Знакомство с иностранцами итальянцами
|
Linear Mode
