Faculty Opinions recommendation of Polycomb response elements mediate the formation of chromosome higher-order structures in the bithorax complex.

Abstract In the studies reported here, we have examined the properties of the Mcp element from the Drosophila melanogaster bithorax complex (BX-C). We have found that sequences from the Mcp region of BX-C have properties characteristic of Polycomb response elements (PREs), and that they silence adjacent reporters by a mechanism that requires trans-interactions between two copies of the transgene. However, Mcp trans-regulatory interactions have several novel features. In contrast to classical transvection, homolog pairing does not seem to be required. Thus, trans-regulatory interactions can be observed not only between Mcp transgenes inserted at the same site, but also between Mcp transgenes inserted at distant sites on the same chromosomal arm, or even on different arms. Trans-regulation can even be observed between transgenes inserted on different chromosomes. A small 800-bp Mcp sequence is sufficient to mediate these long-distance trans-regulatory interactions. This small fragment has little silencing activity on its own and must be combined with other Polycomb-Group-responsive elements to function as a “pairing-sensitive” silencer. Finally, this pairing element can also mediate long-distance interactions between enhancers and promoters, activating mini-white expression.

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Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽

10.32607/20758251-2016-8-2-79-86 ◽

2016 ◽

Vol 8 (2) ◽

pp. 79-86 ◽

Cited By ~ 3

Author(s):

P. V. Elizar’ev ◽

D. V. Lomaev ◽

D. A. Chetverina ◽

P. G. Georgiev ◽

M. M. Erokhin

Keyword(s):

Dna Sequences ◽

Cell Types ◽

Transcription Terminator ◽

Response Elements ◽

Polycomb Response Elements ◽

The Individual ◽

Multicellular Organisms ◽

Different Cell Types ◽

Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

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Microsized Structures Fabricated with Nanoparticles as Building Blocks

MRS Proceedings ◽

10.1557/proc-536-205 ◽

1998 ◽

Vol 536 ◽

Cited By ~ 1

Author(s):

Yongchi Tian ◽

A. D. Dinsmore ◽

S. B. Qadri ◽

B. R. Ratna

Keyword(s):

Radial Growth ◽

Building Blocks ◽

Higher Order ◽

Surfactant Templating ◽

Order Structures

AbstractHere we report a nanoparticulate route to Y2O3 nanofibers (~50 nm in diameter and a few micrometers in length) and for the radial growth of ZnS spheres (200-800 nm diameter). Well-defined higher order structures are developed upon thermostatically aging the dispersions of monomeric nanocrystals. The shapes of the “macromolecules„ are correlated to primary monomeric nanocrystallites, the growing time and temperature, and surfactant templating agents. It is anticipated that this approach should inspire fabrication of nanoparticulate structures by using primary nanoparticles as monomers.

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