Qhov sib txawv tseem ceeb ntawm ITS1 thiab ITS2 yog tias ITS1 yog ib qho DNA spacer nyob nruab nrab ntawm 18S thiab 5.8S rRNA noob hauv eukaryotes, thaum ITS2 yog spacer DNA nyob nruab nrab ntawm 5.8S thiab 28S rRNA noob hauv eukaryotes.
Internal transcribed spacer (ITS) yog tus spacer DNA feem ntau nyob nruab nrab ntawm cov subunit ribosomal RNA me me thiab loj subunit ribosomal RNA noob nyob rau hauv chromosome los yog nyob rau hauv cov cheeb tsam transcribed nyob rau hauv lub polycistronic rRNA precursor transcript molecule. Hauv cov kab mob thiab archaea, tsuas muaj ib qho ITS ntawm 16S thiab 23S rRNA noob. Tab sis hauv eukaryotes, muaj ob ITS spacer DNA: ITS1 (nruab nrab ntawm 18S thiab 5.8S rRNA noob) thiab ITS2 (nruab nrab ntawm 5.8S thiab 28S rRNA). Yog li, ITS1 thiab ITS2 yog ob qhov chaw DNA pom ntawm rRNA noob hauv eukaryotes.
Nws yog dab tsi?
ITS1 yog ib qho DNA spacer nyob nruab nrab ntawm 18S thiab 5.8S rRNA noob hauv eukaryotes. Nws yog hais txog ib qho ntawm cov khoom tsis ua haujlwm DNA nyob nruab nrab ntawm rRNA noob. ITS1 muaj qhov sib txawv ntev dua li ITS2. Qhov ntev variation ntawm ITS1 yog kwv yees li (200-300bp). ITS cov cim xws li ITS1 tau ua pov thawj lawv qhov kev ua tau zoo hauv kev qhia txog kev sib raug zoo ntawm kev sib txawv ntawm cov se sib txawv. Ntxiv mus, ITS1 spacer DNA yog kev txuag tsawg dua li ITS2 spacer DNA. ITS1 cov qauv tsuas yog khaws cia hauv ntau qhov me me taxonomic units. Txhua pawg eukaryotic ribosomal kuj muaj cov cheeb tsam hu ua sab nraud transcribed spacers (5' thiab 3' ETS).
Daim duab 01: ITS1 thaj tsam
The ITS1 spacer DNA yog ze heev rau 5'external transcribed spacer (5'ETS). Tsis tas li ntawd, yog tias ib tus neeg xav kom nthuav dav thaj tsam ITS1 rau kev tshawb fawb txog kev sib raug zoo ntawm kev sib raug zoo, lawv yuav tsum tau siv ib qho tshwj xeeb primer khub (rov qab thiab pem hauv ntej primers) rau lub hom phiaj no. Txhawm rau nthuav dav ITS1 cheeb tsam, ob lub primer teeb feem ntau yog siv hauv PCR raws tu qauv ntawm lub chaw soj nstuam. Lawv yog ITS1 pem hauv ntej thiab ITS2 thim rov qab lossis ITS1 rov qab thiab ITS4 thim rov qab.
Nws yog dab tsi?
ITS2 yog ib qho DNA spacer nyob nruab nrab ntawm 5.8S thiab 28S rRNA noob hauv eukaryotes. ITS2 cheeb tsam muaj qhov sib txawv ntev dua li thaj tsam ITS1. Qhov ntev variation ntawm ITS2 yog kwv yees li (180-240bp). Txawm li cas los xij, thaj tsam ITS2 tau txais kev txuag ntau dua li thaj tsam ITS1 hauv ntau chav nyob hauv taxonomic. Nws txheeb xyuas tias tag nrho cov txheej txheem ITS2 qhia ib qho tseem ceeb ntawm cov qauv thib ob. Ntxiv mus, 40% ITS2 cheeb tsam tau txais kev cawmdim ntawm tag nrho cov angiosperms, thaum nws muaj peev xwm ua kom haum 50% ntawm thaj tsam ITS2 thoob plaws tsev neeg thiab qib siab dua.
Daim duab 02: ITS2 thaj tsam
Txawm li cas los xij ntawm kev txuag, kev siv thaj tsam ITS2 kuj nrov heev xws li thaj tsam ITS1 hauv kev tshawb fawb txog kev sib raug zoo, tshwj xeeb tshaj yog nyob rau hauv fungal DNA barcoding. Txhawm rau nthuav dav ITS2 cheeb tsam, ib qho tshwj xeeb primer teeb feem ntau yog siv hauv PCR raws tu qauv ntawm lub chaw soj nstuam. Qhov ntawd yog ITS1 foward thiab ITS4 thim rov qab. Tab sis thaum PCR raws tu qauv siv cov txheej txheem primer no, nws kuj ua rau thaj tsam ITS1 ua ke nrog thaj tsam ITS2. Tsis tas li ntawd, ITS2 spacer DNA yog ze heev rau 3'external transcribed spacer (3' ETS).
Similarities Ntawm ITS1 thiab ITS2
- ITS1 thiab ITS2 yog ob qhov chaw DNA nyob nruab nrab ntawm rRNA noob.
- Lawv tsuas muaj nyob hauv eukaryotes.
- Ob leeg tuaj yeem nthuav dav los ntawm kev siv cov khub primer tshwj xeeb.
- Lawv ob leeg yog excised nyob rau hauv rRNA maturation as non-functional by-products.
- Ob leeg tseem ceeb heev rau kev tshawb fawb txog kev sib raug zoo, tshwj xeeb tshaj yog nyob rau hauv fungal DNA barcoding.
Qhov txawv ntawm ITS1 thiab ITS2
ITS1 yog qhov chaw DNA muaj nyob nruab nrab ntawm 18S thiab 5.8S rRNA cov noob hauv eukaryotes thaum ITS2 yog cov DNA spacer nyob nruab nrab ntawm 5.8S thiab 28S rRNA noob hauv eukaryotes. Yog li, qhov no yog qhov sib txawv tseem ceeb ntawm ITS1 thiab ITS2. Tsis tas li ntawd, ITS1 muaj qhov sib txawv ntev dua piv rau ITS2. Ntawm qhov tod tes, ITS2 muaj qhov sib txawv ntev dua piv rau ITS1. Nov yog lwm qhov txawv ntawm ITS1 thiab ITS2.
Cov hauv qab no infographic teev qhov sib txawv ntawm ITS1 thiab ITS2 hauv daim ntawv teev npe rau kev sib piv ntawm ib sab.
Summary – ITS1 vs ITS2
Internal transcribed region (ITS) yog ib qho tsis ua haujlwm ntawm spacer DNA nyob nruab nrab ntawm rRNA noob. Hauv cov kab mob thiab archaea, tsuas muaj ib cheeb tsam ITS xwb. Tab sis hauv eukaryotes, muaj ob thaj tsam ITS: ITS1 thiab ITS2. ITS1 yog ib qho DNA spacer uas nyob nruab nrab ntawm 18S thiab 5.8S rRNA noob hauv eukaryotes, thaum ITS2 yog spacer DNA uas nyob nruab nrab ntawm 5.8S thiab 28S rRNA noob hauv eukaryotes. Yog li, qhov no yog cov ntsiab lus ntawm qhov sib txawv ntawm ITS1 thiab ITS2.
