Chromatin insulators block the action of transcriptional enhancers when interposed between an enhancer and a promoter. In this study, we examined the role of chromatin loops formed by two unrelated insulators, gypsy and Fab-7, in their enhancer-blocking activity. To test for this activity, we selected the white reporter gene that is activated by the eye-specific enhancer. The results showed tha...

A strong transcription enhancer was identified in the genomic DNA (235 kb) of human cytomegalovirus (HCMV), a ubiquitous and severe pathogen of the herpesvirus group. Cotransfection of enhancerless SV40 DNA with randomly fragmented HCMV DNA yielded two SV40-HCMV recombinant viruses that had incorporated overlapping segments of HCMV DNA to substitute for the missing SV40 enhancer. Within HCMV, t...

In the human epsilon-globin gene locus, the HS2 enhancer in the Locus Control Region regulates transcription of the embryonic epsilon-globin gene located over 10 kb away. The mechanism of long-range HS2 enhancer function was not fully established. Here we show that the HS2 enhancer complex containing the enhancer DNA together with RNA polymerase II (pol II) and TBP tracks along the intervening ...

We have identified cis-regulatory sequences acting on Otx2 expression in epiblast (EP) and anterior neuroectoderm (AN) at about 90 kb 5' upstream. The activity of the EP enhancer is found in the inner cell mass at E3.5 and the entire epiblast at E5.5. The AN enhancer activity is detected initially at E7.0 and ceases by E8.5; it is found later in the dorsomedial aspect of the telencephalon at E1...

objective(s) the immunoadjuvant potential of cross-linked dextran microspheres (cdm) as absorption enhancer and quillaja saponins (qs) as immunomodulator adjuvant was evaluated. materials and methods cdm loaded or tetanus-mixed toxoid (tt) or quillaja saponin (qs) were nasally administered to rabbits in dry powder form, three times in 2 weeks interval and serum igg and nasal lavage siga titers ...

Enhancers could, in principle, function by increasing the rate of reinitiation on individual adjacent active promoters or by increasing the probability that an adjacent promoter is activated for transcription. We have addressed this issue for the repetitive metazoan rDNA enhancer by microinjecting Xenopus oocytes with enhancer-less and enhancer-bearing genes and determining by EM the frequency ...

Objective(s) The immunoadjuvant potential of cross-linked dextran microspheres (CDM) as absorption enhancer and Quillaja saponins (QS) as immunomodulator adjuvant was evaluated. Materials and Methods CDM loaded or tetanus-mixed toxoid (TT) or Quillaja saponin (QS) were nasally administered to rabbits in dry powder form, three times in 2 weeks interval and serum IgG and nasal lavage sIgA tite...

Using the simian virus 40 "enhancer trap" approach, we have identified a transcription enhancer located just upstream of the major immediate early gene of murine cytomegalovirus. This enhancer has several striking properties. (i) Together with the enhancer of human cytomegalovirus, it is the strongest transcription enhancer found to date. (ii) It is an extremely long enhancer, spanning greater ...