Ectopic expression of a Chlamydomonas mt+-specific homeodomain protein in mt- gametes initiates zygote development without gamete fusion

In Drosophila as well as many vertebrate systems, germ cells form extraembryonically and migrate into the embryo before navigating toward gonadal mesodermal cells. How the gonadal mesoderm attracts migratory germ cells is not understood in any system. We have taken a genetic approach to identify genes required for germ cell migration in Drosophila. Here we describe the role of zfh-1 in germ cell migration to the gonadal mesoderm. In zfh-1 mutant embryos, the initial association of germ cells and gonadal mesoderm is blocked. Loss of zfh-1 activity disrupts the development of two distinct mesodermal populations: the caudal visceral mesoderm and the gonadal mesoderm. We demonstrate that the caudal visceral mesoderm facilitates the migration of germ cells from the endoderm to the mesoderm. Zfh-1 is also expressed in the gonadal mesoderm throughout the development of this tissue. Ectopic expression of Zfh-1 is sufficient to induce additional gonadal mesodermal cells and to alter the temporal course of gene expression within these cells. Finally, through analysis of a tinman zfh-1 double mutant, we show that zfh-1 acts in conjunction with tinman, another homeodomain protein, in the specification of lateral mesodermal derivatives, including the gonadal mesoderm.

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Requirements of Lim1, a Drosophila LIM-homeobox gene, for normal leg and antennal development

Development ◽

10.1242/dev.127.20.4315 ◽

2000 ◽

Vol 127 (20) ◽

pp. 4315-4323 ◽

Cited By ~ 3

Author(s):

T. Tsuji ◽

A. Sato ◽

I. Hiratani ◽

M. Taira ◽

K. Saigo ◽

...

Keyword(s):

Ectopic Expression ◽

Homeobox Genes ◽

Homeobox Gene ◽

Homeodomain Protein ◽

Border Cells ◽

Null Mutant ◽

Tarsal Segment ◽

Segment Boundary ◽

Leg Development ◽

Antagonistic Interactions

During Drosophila leg development, the distal-most compartment (pretarsus) and its immediate neighbour (tarsal segment 5) are specified by a pretarsus-specific homeobox gene, aristaless, and tarsal-segment-specific Bar homeobox genes, respectively; the pretarsus/tarsal-segment boundary is formed by antagonistic interactions between Bar and pretarsus-specific genes that include aristaless (Kojima, T., Sato, M. and Saigo, K. (2000) Development 127, 769–778). Here, we show that Drosophila Lim1, a homologue of vertebrate Lim1 encoding a LIM-homeodomain protein, is involved in pretarsus specification and boundary formation through its activation of aristaless. Ectopic expression of Lim1 caused aristaless misexpression, while aristaless expression was significantly reduced in Lim1-null mutant clones. Pretarsus Lim1 expression was negatively regulated by Bar and abolished in leg discs lacking aristaless activity, which was associated with strong Bar misexpression in the presumptive pretarsus. No Lim1 misexpression occurred upon aristaless misexpression. The concerted function of Lim1 and aristaless was required to maintain Fasciclin 2 expression in border cells and form a smooth pretarsus/tarsal-segment boundary. Lim1 was also required for femur, coxa and antennal development.

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Identifying targets of the rough homeobox gene of Drosophila: evidence that rhomboid functions in eye development

Development ◽

10.1242/dev.116.2.335 ◽

1992 ◽

Vol 116 (2) ◽

pp. 335-346 ◽

Cited By ~ 26

Author(s):

M. Freeman ◽

B.E. Kimmel ◽

G.M. Rubin

Keyword(s):

Cell Fate ◽

Target Genes ◽

Eye Development ◽

Expression Patterns ◽

Ectopic Expression ◽

Homeobox Gene ◽

Homeodomain Protein ◽

Dorsoventral Patterning ◽

Altered Expression ◽

Enhancer Trap Lines

In order to identify potential target genes of the rough homeodomain protein, which is known to specify some aspects of the R2/R5 photoreceptor subtype in the Drosophila eye, we have carried out a search for enhancer trap lines whose expression is rough-dependent. We crossed 101 enhancer traps that are expressed in the developing eye into a rough mutant background, and have identified seven lines that have altered expression patterns. One of these putative rough target genes is rhomboid, a gene known to be required for dorsoventral patterning and development of some of the nervous system in the embryo. We have examined the role of rhomboid in eye development and find that, while mutant clones have only a subtle phenotype, ectopic expression of the gene causes the non-neuronal mystery cells to be transformed into photoreceptors. We propose that rhomboid is a part of a partially redundant network of genes that specify photoreceptor cell fate.

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Ectopic expression of homeodomain protein CDX2 in intestinal metaplasia and carcinomas of the stomach

Cancer Letters ◽

10.1016/s0304-3835(01)00753-4 ◽

2002 ◽

Vol 176 (1) ◽

pp. 47-55 ◽

Cited By ~ 143

Author(s):

Yun-Qing Bai ◽

Hiroshi Yamamoto ◽

Yoshimitsu Akiyama ◽

Hiroyuki Tanaka ◽

Touichirou Takizawa ◽

...

Keyword(s):

Intestinal Metaplasia ◽

Ectopic Expression ◽

Homeodomain Protein

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Functional differences between Ultrabithorax protein isoforms in Drosophila melanogaster: evidence from elimination, substitution and ectopic expression of specific isoforms.

Genetics ◽

10.1093/genetics/136.3.979 ◽

1994 ◽

Vol 136 (3) ◽

pp. 979-991 ◽

Cited By ~ 2

Author(s):

V Subramaniam ◽

H M Bomze ◽

A J López

Keyword(s):

Nervous System ◽

Drosophila Melanogaster ◽

Peripheral Nervous System ◽

Mutant Allele ◽

Stop Codon ◽

Functional Limitation ◽

Ectopic Expression ◽

Protein Isoforms ◽

Homeodomain Protein ◽

Alternatively Spliced

Abstract The homeotic selector gene Ultrabithorax (Ubx) specifies regional identities in multiple tissues within the thorax and abdomen of Drosophila melanogaster. Ubx encodes a family of six developmentally specific homeodomain protein isoforms translated from alternatively spliced mRNAs. The mutant allele Ubx195 contains a stop codon in exon mII, one of three differential elements, and consequently produces functional UBX protein only from mRNAs of type IVa and IVb, which are expressed mainly in the central nervous system. Although it retains activity for other processes, Ubx195 behaves like a null allele with respect to development of the peripheral nervous system, indicating that UBX-IVa and IVb alone do not contribute detectable Ubx function for this tissue. The mutant allele UbxMX17 contains an inversion of exon mII. We find that this allele only produces mRNAs of type IVa, but the expression pattern of the resulting UBX-IVa protein is indistinguishable from that of total UBX protein expression in wild-type embryos. The phenotype of homozygous UbxMX17 embryos indicates that UBX-IVa cannot substitute functionally for other isoforms to promote normal development of the peripheral nervous system. This functional limitation is confirmed by a detailed analysis of the peripheral nervous system in embryos that express specific UBX isoforms ectopically under control of a heat shock promoter. Additional observations suggest that UBX isoforms also differ in their ability to function in other tissues.

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THE ZYGOTE OF CHLAMYDOMONAS MOEWUSII

Canadian Journal of Botany ◽

10.1139/b57-066 ◽

1957 ◽

Vol 35 (6) ◽

pp. 795-804 ◽

Cited By ~ 24

Author(s):

Ralph A. Lewin

Keyword(s):

Vegetative Growth ◽

Gamete Fusion ◽

Sexual Activation ◽

Zygote Development ◽

Chlamydomonas Moewusii

The processes of gamete fusion, zygote development, and zygote germination in Chlamydomonas moewusii are described. Light, previously shown to be essential for vegetative growth and for sexual activation, also appeared to be required for gamete fusion and for zygote maturation, but not for germination. Fully mature zygospores, enclosed in thick, impermeable walls, germinated erratically; experimental efforts to promote their earlier and more regular germination were unsuccessful. Germination as high as 60 to 90% was achieved by limiting the illumination which the zygotes received during their development.

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The C. elegans even-skipped homologue, vab-7, specifies DB motoneurone identity and axon trajectory

Development ◽

10.1242/dev.129.4.853 ◽

2002 ◽

Vol 129 (4) ◽

pp. 853-862 ◽

Cited By ~ 3

Author(s):

Behrooz Esmaeili ◽

Jennifer M. Ross ◽

Cara Neades ◽

David M. Miller ◽

Julie Ahringer

Keyword(s):

Ectopic Expression ◽

Specific Gene ◽

Locomotory Activity ◽

Homeodomain Protein ◽

Independent Manner ◽

C Elegans ◽

Parallel Pathway ◽

And Function ◽

Work Supports ◽

Repressor Activity

Locomotory activity is defined by the specification of motoneurone subtypes. In the nematode, C. elegans, DA and DB motoneurones innervate dorsal muscles and function to induce movement in the backwards or forwards direction, respectively. These two neurone classes express separate sets of genes and extend axons with oppositely directed trajectories; anterior (DA) versus posterior (DB). The DA-specific homeoprotein UNC-4 interacts with UNC-37/Groucho to repress the DB gene, acr-5 (nicotinic acetylcholine receptor subunit). We show that the C. elegans even-skipped-like homoedomain protein, VAB-7, coordinately regulates different aspects of the DB motoneurone fate, in part by repressing unc-4. Wild-type DB motoneurones express VAB-7, have posteriorly directed axons, express ACR-5 and lack expression of the homeodomain protein UNC-4. In a vab-7 mutant, ectopic UNC-4 represses acr-5 and induces an anteriorly directed DB axon trajectory. Thus, vab-7 indirectly promotes DB-specific gene expression and posteriorly directed axon outgrowth by preventing UNC-4 repression of DB differentiation. Ectopic expression of VAB-7 also induces DB traits in an unc-4-independent manner, suggesting that VAB-7 can act through a parallel pathway. This work supports a model in which a complementary pair of homeodomain transcription factors (VAB-7 and UNC-4) specifies differences between DA and DB neurones through inhibition of the alternative fates. The recent findings that Even-skipped transcriptional repressor activity specifies neurone identity and axon guidance in the mouse and Drosophila motoneurone circuit points to an ancient origin for homeoprotein-dependent mechanisms of neuronal differentiation in the metazoan nerve cord.

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The zinc finger proteins Pannier and GATA4 function as cardiogenic factors in Drosophila

Development ◽

10.1242/dev.126.24.5679 ◽

1999 ◽

Vol 126 (24) ◽

pp. 5679-5688 ◽

Cited By ~ 4

Author(s):

K. Gajewski ◽

N. Fossett ◽

J.D. Molkentin ◽

R.A. Schulz

Keyword(s):

Gene Expression ◽

Cell Fate ◽

Zinc Finger ◽

Heart Development ◽

Ectopic Expression ◽

Cell Formation ◽

Homeodomain Protein ◽

Gata Factor ◽

Cardiac Gene Expression ◽

Cardiac Gene

The regulation of cardiac gene expression by GATA zinc finger transcription factors is well documented in vertebrates. However, genetic studies in mice have failed to demonstrate a function for these proteins in cardiomyocyte specification. In Drosophila, the existence of a cardiogenic GATA factor has been implicated through the analysis of a cardial cell enhancer of the muscle differentiation gene D-mef2. We show that the GATA gene pannier is expressed in the dorsal mesoderm and required for cardial cell formation while repressing a pericardial cell fate. Ectopic expression of Pannier results in cardial cell overproduction, while co-expression of Pannier and the homeodomain protein Tinman synergistically activate cardiac gene expression and induce cardial cells. The related GATA4 protein of mice likewise functions as a cardiogenic factor in Drosophila, demonstrating an evolutionarily conserved function between Pannier and GATA4 in heart development.

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The Homeobox Gene cut Interacts Genetically With the Homeotic Genes proboscipedia and Antennapedia

Genetics ◽

10.1093/genetics/149.1.131 ◽

1998 ◽

Vol 149 (1) ◽

pp. 131-142

Author(s):

Laura A Johnston ◽

Bruce D Ostrow ◽

Christine Jasoni ◽

Karen Blochlinger

Keyword(s):

Expression Patterns ◽

Significant Proportion ◽

Ectopic Expression ◽

Homeobox Gene ◽

Homeodomain Protein ◽

Homeotic Genes ◽

Loss Of Function ◽

Regulation Of Expression ◽

Segmental Identity

Abstract The cut locus (ct) codes for a homeodomain protein (Cut) and controls the identity of a subset of cells in the peripheral nervous system in Drosophila. During a screen to identify ct-interacting genes, we observed that flies containing a hypomorphic ct mutation and a heterozygous deletion of the Antennapedia complex exhibit a transformation of mouthparts into leg and antennal structures similar to that seen in homozygous proboscipedia (pb) mutants. The same phenotype is produced with all heterozygous pb alleles tested and is fully penetrant in two different ct mutant backgrounds. We show that this phenotype is accompanied by pronounced changes in the expression patterns of both ct and pb in labial discs. Furthermore, a significant proportion of ct mutant flies that are heterozygous for certain Antennapedia (Antp) alleles have thoracic defects that mimic loss-of-function Antp phenotypes, and ectopic expression of Cut in antennal discs results in ectopic Antp expression and a dominant Antp-like phenotype. Our results implicate ct in the regulation of expression and/or function of two homeotic genes and document a new role of ct in the control of segmental identity.

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