QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

doi: 10.1242/10.1242/dev.00405

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Li, Y. Articles by Wallrath, L. L. Search for Related Content PubMed PubMed Citation Articles by Li, Y. Articles by Wallrath, L. L.

Effects of tethering HP1 to euchromatic regions of the Drosophila genome

¹ Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
² Department of Cell and Structural Biology, University of Illinois, Urbana-Champaign, Urbana, IL 61801, USA

View larger version (36K): [in a new window]   Fig. 1. lacI-HP1 fusion protein co-localizes with endogenous HP1. Polytene chromosomes from expressor stock LH2, expressing lacI-HP1, were squashed and stained with antibodies to HP1 (red) and antibodies to lacI (green). The chromocenter (C) and telomeres (T) are indicated. Complete co-localization is observed as yellow in the merged image.

View larger version (97K): [in a new window]   Fig. 2. Tethered HP1 causes silencing at some, but not all, genomic sites. The left column shows the eye phenotype observed for stocks 157.1, J3.2 and S9.2 with and without tethered GFP-lacI. The middle column shows the eye phenotype with and without tethered lacI-HP1. The right column shows localization of the lacI-HP1 fusion protein on polytene chromosomes. The arrow denotes the location of lac repeats. Polytene chromosomes were stained with antibodies against lacI (green).

View larger version (54K): [in a new window]   Fig. 3. Tethered lacI-HP1 causes ectopic associations. Third instar larvae of stocks 157.1, 157.4.112 and P2.5 expressing lacI-HP1 were stained with antibodies to lacI (green). Arrows indicate the locations of lac repeats. The percent of nuclei showing ectopic associations, out of 60 nuclei scored for each cytological position, are shown at the bottom of each panel. Associations were observed between the tethered site and other HP1-containing sites (A,B), but were also observed at sites not enriched with HP1 (C).

View larger version (60K): [in a new window]   Fig. 4. HP1 functions downstream of SU(VAR)3-9. (A) The lac repeats show a low level of HP1 and H3 K9 methylation in the absence of lacI-HP1. Polytene chromosomes from stock 157.1 containing a reporter transgene with 256 copies of lac repeats were stained with antibodies to HP1 (green) and antibodies to H3 K9 di-methyl (red). Arrows indicate the locations of lac repeats. (B) Tethered HP1 does not intensify H3 K9 methylation. Strong staining is observed for the HP1 antibody, but not the H3 K9 di-methyl antibody, upon expression of lacI-HP1. (C) Expression of a Su(var)3-9-EGFP transgene leads to recruitment of SU(VAR)3-9-EGFP (upper row) and increased H3 K9 methylation (bottom row). (D) Silencing by tethered HP1 (stock 157.1) was unaffected in Su(var)3-906 hetero- and homozygotes as indicated by a white eye phenotype (middle and bottom rows). The homozygous Su(var)3-906 flies show a rough eye phenotype due to the roughest mutation used as a marker on the Su(var)3-906-bearing chromosome (bottom row). By contrast, Su(var)3-906 heterozygotes show suppression of white gene in In(1)wm4, a stock carrying an inversion placing the white gene next to centric heterochromatin, and 118E-10 a stock carrying a hsp70-white P-element inserted within centric heterochromatin.