Transvection is the phenomenon by which the expression of a gene can be controlled by its homologous counterpart in trans, presumably due to pairing of alleles in diploid interphase cells. Transvection or trans-sensing phenomena have been reported for several loci in Drosophila, the most thoroughly studied of which is the Bithorax-Complex (BX-C). It is not known how early trans-sensing occurs nor the extent or duration of the underlying physical interactions. We have investigated the physical proximity of homologous genes of the BX-C during Drosophila melanogaster embryogenesis by applying fluorescent in situ hybridization techniques together with high-resolution confocal light microscopy and digital image processing. The association of homologous alleles of the BX-C starts in nuclear division cycle 13, reaches a plateau of 70% in postgastrulating embryos, and is not perturbed by the transcriptional state of the genes throughout embryogenesis. Pairing frequencies never reach 100%, indicating that the homologous associations are in equilibrium with a dissociated state. We determined the effects of translocations and a zeste protein null mutation, both of which strongly diminish transvection phenotypes, on the extent of diploid homologue pairing. Although translocating one allele of the BX-C from the right arm of chromosome 3 to the left arm of chromosome 3 or to the X chromosome abolished trans-regulation of the Ultrabithorax gene, pairing of homologous alleles surprisingly was reduced only to 20–30%. A zeste protein null mutation neither delayed the onset of pairing nor led to unpairing of the homologous alleles. These data are discussed in the light of different models for trans-regulation. We examined the onset of pairing of the chromosome 4 as well as of loci near the centromere of chromosome 3 and near the telomere of 3R in order to test models for the mechanism of homologue pairing.

REFERENCES

Akam
M. E.
,
Martinez-Arias
A.
(
1985
)
The distribution of Ultrabithorax transcripts in Drosophila embryos.
EMBO J
4
,
1689
1700
Allis
C. D.
,
Waring
G. L.
,
Mahowald
A. P.
(
1977
)
Mass isolation of pole cells from Drosophilamelanogaster.
Dev. Biol
56
,
372
381
Babu
P.
,
Selvakumar
K. S.
,
Bhosekar
S.
(
1987
)
Studies on transvection at the Bithorax Complex in Drosophila melanogaster.
Mol. Gen. Genet
210
,
557
563
Bender
W.
,
Akam
M.
,
Karch
F.
,
Beachy
P. A.
,
Peifer
M.
,
Spierer
P.
,
Lewis
E. B.
,
Hogness
D. S.
(
1983
)
Molecular Genetics of the Bithorax Complex in Drosophila melanogaster.
Science
221
,
23
29
Benson
M.
,
Pirrotta
V.
(
1988
)
The Drosophila zeste protein binds cooperatively to sites in many gene regulatory regions: implications for transvection and gene regulation.
EMBO J
12
,
3907
3915
Bickel
S.
,
Pirrotta
V.
(
1990
)
Self-association of the Drosophila zeste protein is reponsible for transvection effects.
EMBO J
9
,
2959
2967
Biggin
M. D.
,
Bickel
S.
,
Benson
M.
,
Pirrotta
V.
,
Tjian
R.
(
1988
)
zeste encodes a sequence-specific transcription factor that activates the Ultrabithorax promoter in vitro.
Cell
53
,
713
722
Bodmer
R.
,
Carretto
R.
,
Nung Jan
Y.
(
1989
)
Neurogenesis of the peripheral nervous system in Drosophila Embryos: DNA replication patterns and cell lineages.
Neuron
3
,
21
32
Buchenau
P.
,
Arndt-Jovin
D. J.
,
Saumweber
H.
(
1993
)
In vivo observation of the puff-specific protein no-on transient A (NONA) in nuclei of Drosophila embryos.
J. Cell Sci
106
,
189
199
Buchenau
P.
,
Saumweber
H.
,
Arndt-Jovin
D. J.
(
1997
)
The dynamic nuclear redistribution of an hnRNP K-homologous protein during Drosophila embryo development and heat shock. Flexibility of transcription sites in vivo.
J. Cell Biol
137
,
291
303
Castelli-Gair
J.
,
Greig
S.
,
Micklem
G.
,
Akam
M.
(
1994
)
Dissecting the temporal requirements for homeotic gene function.
Development
120
,
1983
1995
Castelli-Gair
J. E.
,
Micol
J. L.
,
García-Bellido
A.
(
1990
)
Transvection in the DrosophilaUltrabithorax gene: a Cbx1 mutant allele induces ectopic expression of a normal allele in trans.
Genetics
126
,
177
184
Chen
J. D.
,
Chan
C. S.
,
Pirrotta
V.
(
1992
)
Conserved DNA binding and self-association domains of the Drosophila z este protein.
Mol. Cell. Biol
12
,
598
608
Chen
J. D.
,
Pirrotta
V.
(
1993
)
Multimerization of the Drosophila zeste protein is required for efficient DNA binding.
EMBO J
12
,
2075
2083
Chen
J. D.
,
Pirrotta
V.
(
1993
)
Stepwise assembly of hyperaggregated forms of Drosophila zeste mutant protein suppresses white gene expression in vivo.
EMBO J
12
,
2061
2073
Cook
P. R.
(
1997
)
The transcriptional basis of chromosome pairing.
J. Cell Sci
110
,
1033
1040
Csink
A. K.
,
Henikoff
S.
(
1996
)
Genetic modification of heterochromatic association and nuclear organization in Drosophila.
Nature
381
,
529
531
Dernburg
A. F.
,
Broman
K. W.
,
Fung
F. C.
,
Marshall
W. F.
,
Philips
J.
,
Agard
D. A.
,
Sedat
J. W.
(
1996
)
Perturbation of nuclear architecture by long-distance chromosome interactions.
Cell
85
,
745
759
Dillon
N.
,
Grosveld
F.
(
1993
)
Transcriptional regulation of multigene loci: multilevel control.
Trends Genet
9
,
134
137
Edgar
B.
,
O'Farrell
P.
(
1990
)
The three postblastoderm cell cycles of Drosophila embryogenesis are regulated in G2by string.
Cell
62
,
469
480
Fauvarque
M.-O.
,
Zuber
V.
,
Dura
J.-M.
(
1995
)
Regulation of polyhomeotic transcription may involve local changes in chromatin activity in Drosophila.
Mech. Dev
52
,
343
355
Foe
V. E.
,
Alberts
B. M.
(
1983
)
Studies of nuclear and cytoplasmic behaviour during the five mitotic cycles that precede gastrulation in Drosophila embryogenesis.
J. Cell Sci
61
,
31
70
Fung
J.
,
Marshall
W.
,
Dernburg
A.
,
Agard
D.
,
Sedat
J.
(
1998
)
Homologous chromosome pairing in Drosophila melanogaster proceeds through multiple independent inititations.
J. Cell. Biol
141
,
5
20
García-Bellido
A.
,
Wandosell
F.
(
1978
)
The effect of inversions on mitotic recombination in Drosophila melanogaster.
Mol. Gen. Genetics
161
,
317
321
Gelbart
W. M.
(
1982
)
Synapsis-dependent allelic complementation at the decapentaplegic gene complex in Drosophila melanogaster.
Proc. Natl. Acad. Sci. USA
79
,
2636
2640
Gelbart
W. M.
,
Wu
C.-T.
(
1982
)
Interactions of zeste mutations with loci exhibiting transvection effects in Drosophila melanogaster.
Genetics
102
,
179
189
Goldsborough
A. S.
,
Kornberg
T. B.
(
1996
)
Reduction of transcription by homologue asynapsis in Drosophila imaginal discs.
Nature
381
,
807
810
Golic
M. M.
,
Golic
K. G.
(
1996
)
A quantitative measure of the mitotic pairing of alleles in Drosophila melanogaster and the influence of structural heterozygosity.
Genetics
143
,
385
400
Gubb
D.
,
Ashburner
M.
,
Roote
J.
,
Davis
T.
(
1990
)
A novel transvection phenomenon affecting the white gene of Drosophila melanogaster.
Genetics
126
,
167
176
Gubb
D.
,
Roote
J.
,
Trenear
J.
,
Coulson
D.
,
Ashburner
M.
(
1997
)
Topological constrains on transvection between white genes within the transposing element TE35B in Drosophila melanogaster.
Genetics
146
,
917
937
Hanscombe
O.
,
Whyatt
D.
,
Fraser
P.
,
Yannoutsos
N.
,
Greaves
D.
,
Dillon
N.
,
Grosveld
F.
(
1991
)
Importance of globin gene order for correct developmental expression.
Genes Dev
5
,
1387
1394
Hartl
D.
,
Nurminsky
D.
,
Jones
R.
,
Lozovskaya
E.
(
1994
)
Genome structure and evolution in Drosophila: applications of the framework P1 map.
Proc. Natl. Acad. Sci. USA
91
,
6824
6829
Heimer
G. V.
,
Taylor
C. E. D.
(
1974
)
Improved mountant for immunofluorescence preparations.
J. Clin. Path
27
,
254
256
Hell
S.
,
Reiner
G.
,
Cremer
C.
,
Stelzer
E. H. K.
(
1993
)
Aberrations in confocal fluorescence microscopy induced by mismatches in refractive index.
J. Microsc
169
,
391
405
Henikoff
S.
(
1997
)
Nuclear organization and gene expression: homologous pairing and long-range interactions.
Curr. Opin. Cell Biol
9
,
388
395
Hiraoka
Y.
,
Agard
D.
,
Sedat
J.
(
1990
)
Temporal and spatial coordination of chromosome movement, spindle formation, and nuclear envelope breakdown during prometaphase in Drosophila melanogaster embryos.
J. Cell Biol
111
,
2815
2828
Hiraoka
Y.
,
Dernburg
A. F.
,
Parmelee
S. J.
,
Rykowski
M. C.
,
Agard
D. A.
,
Sedat
J. W.
(
1993
)
The onset of homologous chromosome pairing during Drosophila melanogaster embryogenesis.
J. Cell Biol
120
,
591
600
Hopmann
R.
,
Duncan
D.
,
Duncan
I.
(
1995
)
Transvection in the iab-5,6,7 region of the Bithorax Complex of Drosophila: Homology independent interactions in trans.
Genetics
139
,
815
833
James
T. C.
,
Eissenberg
J. C.
,
Craig
C.
,
Dietrich
V.
,
Hobson
A.
,
Elgin
S. C. R.
(
1989
)
Distribution Patterns Of HP1 a heterochromatin-associated nonhistone chromosomal protein of Drosophila.
Eur. J. Cell Biol
50
,
170
180
Jijakli
H.
,
Ghysen
A.
(
1992
)
Segmental determination in Drosophila central nervous system: analysis of the abdominal-A region of the Bithorax Complex.
Int. J. Dev. Biol
36
,
93
99
Kleckner
N.
,
Weiner
B. M.
(
1993
)
Potential advantages of unstable interactions for pairing of chromosomes in meiotic, somatic, and premeiotic Cells.
Cold Spring Harbor Symp. Quant. Biol
58
,
553
565
Kubitscheck
U.
,
Wedekind
P.
,
Peters
R.
(
1994
)
Lateral diffusion measurement at high spatial resolution by scanning microphotolysis in a confocal microscope.
Biophys. J
67
,
948
956
Lehner
C.
,
O'Farrell
P.
(
1989
)
Expression and function of Drosophila cyclin A during embryonic cell cycle progression.
Cell
56
,
957
968
Leiserson
W.M.
,
Bonini
N. M.
,
Benzer
S.
(
1994
)
Transvection at the eyes absent gene of Drosophila.
Genetics
138
,
1171
1179
Lifton
R.
,
Goldberg
M.
,
Karp
R.
,
Hogness
D.
(
1978
)
The organization of the histone genes in Drosophila melanogaster: Functional and evolutionary implications.
Cold Spring Harbor Symp. Quant. Biol
43
,
1047
1051
Locke
J.
,
McDermid
H. E.
(
1993
)
Analysis of Drosophila chromosome 4 using pulsed field gel electrophoresis.
Chromosoma
102
,
718
723
Marshall
W.
,
Straight
A.
,
Marko
J.
,
Swedlow
J.
,
Dernburg
A.
,
Belmont
B.
,
Murray
A.
,
Agard
D.
,
Sedat
J.
(
1997
)
Interphase chromosomes undergo constrained diffusional motion in living cells.
Curr. Biol
7
,
930
939
Martinez-Laborda
A.
,
González-Reyes
A.
,
Morata
G.
(
1992
)
Trans regulation in the Ultrabithorax gene of Drosophila: alterations in the promoter enhance transvection.
EMBO J
11
,
3645
3652
Mathog
D.
(
1990
)
Transvection in the Ultrabithorax domain of the Bithorax complex of Drosophila melanogaster.
Genetics
125
,
371
382
Merriam
J.
,
García-Bellido
A.
(
1972
)
A model for somatic pairing derived from somatic crossing over with third chromosome rearrangements in Drosophila melanogaster.
Mol. Gen. Genet
115
,
302
313
Metz
C. W.
(
1916
)
Chromosome studies of the Diptera. II: the paired association of chromosomes in the Diptera, and its significance.
J. Exp. Zool
21
,
213
279
Micol
J.-L.
,
García-Bellido
A.
(
1988
)
Genetic analysis of ‘transvection’ effects involving Contrabithorax mutations in Drosophila melanogaster.
Proc. Natl. Acad. Sci. USA
85
,
1146
1150
Miklos
G. L. G.
,
Yamamoto
M. T.
,
Davies
J.
,
Pirrotta
V.
(
1988
)
Microcloning reveals a high frequency of repetitive sequences characteristic of chromosome 4 and the beta heterochromatin of Drosophila melanogaster.
Proc. Natl. Acad. Sci. USA
85
,
2051
2055
Pardue
M.
,
Kedes
L.
,
Weinberg
E.
,
Birnstiel
M.
(
1977
)
Localization of sequences coding for histon messenger RNA in the chromosomes of Drosophila melanogaster.
Chromosoma
63
,
135
151
Paro
R.
(
1993
)
Mechanisms of heritable gene repression during development of Drosophila.
Curr. Opin. Cell Biol
5
,
999
1005
Peterson
K. M.
,
Davis
P. S.
,
Judd
B. H.
(
1994
)
The determined state of white expression in the Drosophila eye is modified by zeste1 in the wzm family of mutants.
Mol. Gen. Genet
242
,
717
726
Pirrotta
V.
(
1991
)
The genetics and molecular biology of zeste in Drosophila melanogaster.
Adv. in Genetics
29
,
301
348
Pirrotta
V.
(
1995
)
Chromatin complexes regulating gene expression in Drosophila.
Curr. Opin. Genet. Dev
5
,
466
472
Pirrotta
V.
,
Bickel
S.
,
Mariani
C.
(
1988
)
Developmental expression of the Drosophila zeste gene and localization of zeste protein on polytene chromosomes.
Genes Dev
2
,
1839
1850
Ptashne
M.
(
1988
)
How eukaryotic transcriptional activators work.
Nature
335
,
683
689
Risau
W.
,
Saumweber
H.
,
Symmons
P.
(
1981
)
Monoclonal antibodies against a nuclear membrane protein of Drosophila.
Exp. Cell Res
133
,
47
54
Robinett
C. C.
,
Straight
A.
,
Li
G.
,
Willhelm
C.
,
Sudlow
G.
,
Murray
A.
,
Belmont
A. S.
(
1996
)
In vivo localization of DNA sequences and visualization of large-scale chromatin organization using lac operator/repressor recognition.
J. Cell Biol
135
,
1685
1700
Sigrist
C. J. A.
,
Pirrotta
V.
(
1997
)
Chromatin insulator elements block the silencing of a target gene by the Drosophila Polycomb Response Element (PRE) but allow trans interactions between PREs on different chromosomes.
Genetics
147
,
209
221
Simon
J.
(
1995
)
Locking in stable states of gene expression: transcriptional control during Drosophila development.
Curr. Opin. Cell Biol
7
,
376
385
Smolik-Utlaut
S.
,
Gelbart
W.
(
1987
)
The effects of chromosomal rearrangements on the zeste-white interaction in Drosophila melanogaster.
Genetics
116
,
285
298
Strouboulis
J.
,
Dillon
N.
,
Grosveld
F.
(
1992
)
Developmental regulation of a complete 70 kb human-globin locus in transgenic mice.
Genes Dev
6
,
1857
1864
Strutt
H.
,
Cavalli
G.
,
Paro
R.
(
1997
)
Co-localization of Polycomb protein and GAGA factor on regulatory elements responsible for the maintenance of homeotic gene expression.
EMBO J
16
,
3621
3632
Swedlow
J. R.
,
Sedat
J. W.
,
Agard
D. A.
(
1993
)
Multiple chromosomal populations of topoisomerase II detected in vivo by time-lapse, three-dimensional wide-field microscopy.
Cell
73
,
97
108
Tartof
K. D.
,
Henikoff
S.
(
1991
)
Trans-sensing effects from Drosophila to Humans.
Cell
65
,
201
203
Verveer
P. J.
,
Jovin
T. M.
(
1997
)
Efficient superresolution restoration algorithms using maximum a posteriori estimations with application to fluorescence microscopy.
J. Opt. Soc. Am
14
,
1696
1706
Wedekind
P.
,
Kubitscheck
U.
,
Heinrich
O.
,
Peters
R.
(
1996
)
Linescanning microphotolysis for diffraction-limited measurements of lateral diffusion.
Biophys. J
71
,
1621
1632
White
R. A. H.
,
Wilcox
M.
(
1985
)
Distribution of Ultrabithorax proteins in Drosophila.
EMBO J
4
,
2035
2043
Wijgerde
M.
,
Grosveld
F.
,
Fraser
P.
(
1995
)
Transcription complex stability and chromatin dynamics in vivo.
Nature
377
,
209
213
Wu
C.-t.
(
1993
)
Transvection, nuclear structure, and chromatin Proteins.
J. Cell Biol
120
,
587
590
Wu
C.-T.
,
Goldberg
M. L.
(
1989
)
The Drosophila zeste gene and transvection.
Trends Genet
5
,
189
194
Zalokar
M.
,
Erk
I.
(
1977
)
Phase-partition fixation and staining of Drosophila eggs.
Stain Technol
52
,
89
95
This content is only available via PDF.