Lecture6mcb160Lf11

Lecture6mcb160Lf11 - Intron 3 is not removed; translation...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Intron 3 is not removed; translation hits STOP in intron No transposase activity UGA From lab manual- also see figure legend there Note that IVS = intervening sequence = intron in current lingo In lab 2 you set up: Cross 1.0 Purpose is to place transposase source p[Δ2-3] (from father) and movable p[w+] element (from mother) in the same F1 genome Females w p[w+ Gal4]; + ; + ; + x males w ; + ; TMS, Sb p[ Δ2-3] ; + w p[w+Gal 4] + + + Y+ LVM + F1 Progeny: Females w p[w+ Gal4]; + ; TMS, Sb p[Δ 2-3] w + + Males w p[w+ Gal4]; + ; TMS, Sb p[Δ2-3] Y + + or LVM ; + + + or LVM ; + + + Cross 1.1 a-c (Experimental) Purpose: Generate progeny with transpositions of p[w+] from X onto autosomes Females y w ; +;+;+ x F1 Sb males (provided) y w + + + Cross 1.1d Control) Females y w ; +;+;+ x F1 normal bristle males (provided) y w + + + Transposition of P element followed by DNA repair In this example, the P element reinserts into a new site (right). In addi8on, the excision site is repaired using the homologous sequence to restore the original P element. A=er chromosome segrega8on, one daughter cell now has 2 copies of the P element in the genome. ! h@p://engels.gene8cs.wisc.edu/Pelements/fig3.html How P element transposition results in changes in copy number of P elements P 1.  No transposi8on P P mitosis P P No change in #: 1 copy of P per cell The transposi-on example to the right only shows one scenario, failure to repair P accompanied by inser-on on another chromosome. In addi-on, if the excision site was repaired to P (as on the previous slide), then every cell would inherit at least one copy, but could have 2 copies if it also inherited a new inser-on. In contrast, if there is a failure to insert in a new loca-on and a failure to repair, that produces more divisions yielding 1 or 0 copies. 2. With transposi8on replica8on P P Repair does NOT restore P P P P Inserts elsewhere (drawn as another mitosis chromosome but could be same one) P P Cell inherits chroma8d repaired to P and new inser8on = 2 copies Sister cell inherits neither = 0 copies OR P Cell inherits chroma8d that is not repaired to P and new inser8on = 1 copy Sister cell inserts chroma8d repaired to P but not new inser8on = 1 copy Change in #- 0,1 or 2 copies of P per cell # p[w+] copies in genome Color of cell in eye two or more dark orange to red one (original #) orange none white Note that in a lineage with 2 copies, transposi-on can occur again to produce 3 sites of inser-on, etc. However a lineage that inherits 0 copies is fixed in that state. Somatic transposition in the eye produces a variegated (mosaic eye) Transposition in the germline cells can result in the inheritance of the P element in new chromosomal locations. Soma8c transposi8on in the eye produces a variegated (mosaic eye) 1 copy Transposi8on event occurs 2 copies Cell lineage in developing eye. P element transposi8ons create patches (clones) of cells with different color. Transposi8on in germline cells can result in the inheritance of the P element in new chromosomal loca8ons Transposi8on event occurs 1 copy Transposi8on event occurs Transposi8on event occurs 0 copies 2 copies ­ original plus new inser8on 1 copy ­ 0 copies 1 copy ­new original inser8on inser8on Sperm with different copy numbers of pw+ that can be inherited Crosses 1.1.a-c - Purpose: Generate and isolate transpositions of p[w+] from X onto autosomes y w / y w ; + / + ; + / + ♀♀ X w p[w+] / Y ; + / + ; TMS, Sb p[Δ2-3] / + ; +/+ ♂♂ transpositions occuring in germline Progeny predicted by Mendelian genetics (p[w+] stays associated only with X) y w / w p[w+]; +/+; TMS, Sb p[∆2 ­3]/+; +/+ y w/ Y; +/+; TMS, Sb p[∆2 ­3]/+; +/+ y w / w p[w+]; +/+; +/+ ; +/+ y w/ Y; +/+; +/+ ; +/+ orange ­eyed, Sb or nonSb females yellow, white, Sb or nonSb males “Exceptional” progeny resulting from transpositions to the autosomes in father’s germline female eye male eye y w / w p[w+]; autosomal p[w+] darker y w/ Y; autosomal p[w+] orange y w/ w p[w+]; autosomal p[w+] orange X Actual genotypes of these y w/ w p[w+]; no autosomal p[w+] white X excep8onal males X means p[w+] excised and wasn’t repaired to p[w+] y w/Y; pw+/II; III/III; IV/ IV…on ch.2 y w/Y; II/II; pw+/III; IV/IV ….ch. 3 y w/Y; II/II; III/III; pw+/IV …ch.4 (rare) Third chromosome in these excep8onal males could be + or TMS,Sb p[∆2 ­3]. If you now wanted to analyze the P ­element inser8on in a stable form (no more transposi8on), would you select Sb or non ­Sb excep8onal males for your next cross? ...
View Full Document

Ask a homework question - tutors are online