1. The gene trap resource: A treasure trove for hemopoiesis research
Ariel Forrai, Lorraine Robb 
Experimental Hematology 
Volume 33, Issue 8, Pages (August 2005)
DOI: /j.exphem
Copyright © 2005 International Society for Experimental Hematology Terms and Conditions

2. Figure 1 Overview of gene trapping.
Experimental Hematology  , DOI: ( /j.exphem )
Copyright © 2005 International Society for Experimental Hematology Terms and Conditions

3. Figure 2
Promoter and gene trap vectors. (A): Promoter trap vector. In this example the vector is a β-geo cassette. If the vector integrates into an exon of a transcriptionally active locus a fusion transcript between the endogenous transcript and the reporter will be generated. Other integrations will not give rise to neomycin-resistant ES cell clones. (B): Gene trap vector. The vector shown here is IRESβgalNeo+pA. The 5′ splice acceptor site enables formation of a fusion transcript even when the trap vector inserts into an intron. In this vector, the neomycin resistance cassette has its own promoter and polyadenylation signal sequence. Therefore neomycin-resistant gene trap ES cell clones will be generated whenever the vector inserts into the host genome, irrespective of whether the insertion is into a genetic locus. LacZ, β-galactosidase; β-geo, β-galactosidase-neomycin resistance fusion cassette; PGK, phosphoglycerate kinase promoter; pA, polyadenylation signal sequence; IRES, internal ribosome entry sequence; SA, splice acceptor; neo, neomycin phosphotransferase gene cassette.
Experimental Hematology  , DOI: ( /j.exphem )
Copyright © 2005 International Society for Experimental Hematology Terms and Conditions

4. Figure 3
Expression of the β-galactosidase gene trap reporter in differentiation cultures of gene trap ES cell clones containing stromal cells, blood cells, and endothelial cells. Clones were differentiated as embryoid bodies for 4 days and then plated on tissue culture plastic to allow adherence. Five days later, the cultures were fixed and stained for lacZ and photographed. (A): Negative for lacZ staining. The culture contains blood islands ascular channels filled with round refractile cells, the majority of which can be shown to be red blood cells by 2-7-diamino-fluorene staining for hemoglobin (not shown). (B): Endothelial cells and a few cells within the blood islands positive for lacZ. (C): Endothelial cells surrounding vascular channels with endothelial cells positive for lacZ. (D): Many cells within blood islands staining positively for lacZ. (E,F): Rare lacZ-positive cells in blood islands (E). The boxed area is shown at higher power in (F). BI: blood islands, E: endothelial cells.
Experimental Hematology  , DOI: ( /j.exphem )
Copyright © 2005 International Society for Experimental Hematology Terms and Conditions

5. Figure 4
Reporter gene expression in a gene trap ES cell clone and in embryos with an insertion into the Tssc6/Phemx locus. (A): LacZ staining is detectable in cells within the blood islands of differentiated cultures of the gene trap ES cell clone with an insertion into the Tssc6 locus. (B): The gene trap ES cell clone was used to generate mice (Tssc6gt/gt) [34]. Analysis of reporter gene expression in the Tssc6gt/gt mice showed expression in the blood islands of 7.5 dpc embryos (arrow). (C): Primitive blood cells within the yolk sac blood island staining for lacZ (arrows). (D): LacZ expression in the fetal liver of Tssc6gt/gt E13.5 embryos (arrow).
Experimental Hematology  , DOI: ( /j.exphem )
Copyright © 2005 International Society for Experimental Hematology Terms and Conditions