Genes controlling pattern formation in Drosophila embryogenesis
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| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| dicephalic (dic) | Maternal | Abnormal position of nurse cells relative to oocyte | Contributes to anteroposterior polarity of nurse cell oocyte complex | |
| gurken (grk) | Oocyte | Eggs ventralized with dorsal appendages reduced or missing | Similar to vertebrate transforming growth factor alpha (TGF-α), ligand for torpedo | Establishes first posterior and then dorsal identity of ovarian follicle cells |
| spindle (spn) (several loci) | Maternal germ line | Disturbed anteroposterior polarity of oocyte | Determination of prospective oocyte among cystocytes | |
| torpedo (trp) | Ovarian follicle cells | Similar to grk | Receptor tyrosine kinase, receptor for grk | Same as grk |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| bicoid (bcd) | mRNA transcribed in nurse cells and transported to anterior of oocyte. Translated during cleavage. Protein forms anteroposterior gradient. | Head and thorax replaced with mirror image of telson | Transcriptional regulator (homeodomain and paired repeat) | Activates hb transcription; acts as a morphogen on embryonic genes; expressed anteriorly |
| exuperantia (exu) | Testis and ovary | Reducion of head; defective gastrulation | RNA-binding protein | Needed to transport bcd mRNA from nurse cells to oocyte |
| hunchback (hb) | See Zygotic Anteroposterior Gap Class | |||
| staufen (stau) | Maternal germ line, emryonic central nervous system | Most abdominal segments missing, no pole cells, also head defects | Double-stranded RNA-binding protein | Required for bicoid mRNA localization and polar granule assembly |
| swallow (swa) | Maternal germ line | Reduction of head; cellularization defects | Rna-binding protein | Required for localization of bcd mRNA |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| cappuccino (capu) | Maternal | Abdominal segments A2-A7 missing; no pole cells | Putative transmembrane receptor | Required for polar granule assembly |
| nanos | Transcription in oocyte and nurse cells. Partial localization to polar granules. Only this localized mRNA is translated. | Absence of abdomen; pole cells normal | RNA-binding protein, translational repressor | Inhibits translation of maternal hb mRNA and hastens its destruction, hence allows activation of kni in posterior. |
| oskar (osk) | Maternal germ line | Similar to capu | Required for polar granule assembly, localizes nos mRNA | |
| pumilio (pum) | Transcription maternal. Protein probably localized to posterior | Most of abdomen missing; pole cells normal | RNA-binding protein | Recruits nos protein to hb mRNA |
| spire (spir) | Maternal | Similar to capu | Actin-binding protein | Required for polar granule assembly |
| staufen (stau) | See maternal anterior system | |||
| tudor (tud) | Male and female germ line | Similar to capu | Required for pole cell formation | |
| vasa (vas) | Transcription in nurse cells and oocyte; mRNA uniform in early embryo. Protein localized in posterior of oocyte, egg, and in pole cells. | Similar to capu | RNA helicase | Required for pole cell formation |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| NTF-1 | Transcriptional inhibitor | Inhibits transcription of hkb and tll | ||
| torso (tor) | Transcription in nurse cells. Transport to oocyte, where protein distributed uniformly in plasma membrane. | Absence of labrum, reduction of head skeleton, absence of A8 and telson; gain of function; suppression of segmentation in thorax and abdomen | Tyrosine kinase receptor, likely receptor for active trunk protein | Activates tll hkb by inhibiting NTF-1 |
| torsolike (tsl) | Protein secreted by anterior and posterior ovarian follicle cells probably associates with vitelline envelope near egg poles | Similar to tor (loss of function only) | Modifying protein | Generates active form of trunk near egg poles |
| Trunk (trk) | Maternal mRNA translated in early embryo, protein released into preivitelline space | Similar to tor | Secreted protein | Probably ligand of tor, after processing by tsl |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| empty spiracles | Transcription during blastoderm 78-67% EL; later, in cells forming tracheal pits and spiracles | Defects in antennal segment, tracheal system | Transcriptional regulator (homeodomain) | Specifies procephalic segments |
| giant (gt) | Initial transcription at preblastoderm stage 82-60% and 33-0% EL; changes later | Defects in or absence of labrum, labium, and abdominal segments | Transcriptional regulator (Leucine zipper) | Activates Scr; represses Kr |
| huckebein (hkb) | Anterior and posterior ends of blastoderm | Defects in terminal body structures and gut | Transcriptional regulator (zinc finger domain) | Specifies terminal structures in concert with tll |
| hunchback (hb) | Maternal mRNA initially uniform; protein forms anteroposterior gradient. Embryonic transcription 100-50% EL and 20-10% EL. Posterior domain long-lasting. | Embryonic: deletion of labium, thorax, aA7/pA8 (PS 13). No pure maternal effect, but if mother and sperm are hb-, then deletion of all mouthparts and thoracic segments and A1-A3, with mirror duplication of abdomen. | Transcriptional regulator (zinc finger domain) | Represses kni; represses Kr at high level and activates at low level; regulates eve; regulates h, run, ftz; activates Antp (with ftz); represses Ubx |
| knirps (kni) | Transcription starts at preblastoderm stage forming zone 45-30% EL. Ventral patch and narrow ring form in atnerior by cellular blastoderm stage. | Replacement of A1-A7 by single A-type segment | Transcriptional regulator (zinc finguer) | Represses Kr; regulates h, run, eve, ftz; represses Abd-B and Antp |
| Krüppel (Kr) | Transcription starts at preblastoderm stage in central zone, eventually expanding to 60-30% EL. Later also posterior patch and patch in head. | Purely embryonic. Head normal, deletion of thorax and A1-A5. Duplicated inverted A6. | Trancriptional regulator (zinc finguer) | Activates kni; represses gt; regulates eve; regulates h, run, ftz; represses Scr; activates Antp; represses Abd-B |
| orthodenticle (otd) | Narrow band (75-92% EL) in anterior blastoderm | Defects in eyes and anterior head parts | Transcriptional regulator (homeodomain, paired domain) | Activated by bcd and tor, otd - along with ems - specifies procephalic segments |
| tailless (tll) | Transcription in termini of preblastoderm embryo | Head skeleton reduced but labrum present. Hindgut, Malpighian tubules absent. | Transcriptional regulator (steroid receptor family) | Activates hb; represses Kr; represses kni; activates h |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| even-skipped (eve) | Transcription starts at preblastoderm stage; 7 stripes corresponding to parasegments 1, 3, 5, etc., by cellularization stage. Fades during gastrulation. | Abolishes segmentation, giving lawn of denticles. Weak alleles delete odd parasegments. | Transcriptional regulator (homeodomain) | Represses ftz, odd, run; activates itself; activates en; represses wg; activates Dfd |
| fushi tarazu (ftz) | Transcription starts at preblastoderm stage; 7 stripes corresponding to parasegments 2, 4, 6, etc., by cellularization. Fades during germ band extension. | Deletes even parasegments | Transcriptional regulator (homeodomain) | Activates itself; activates en; activates Antp; activates Ubx; represses wg |
| hairy (h) | Transcription starts at preblastoderm stage; 7 stripes + dorsal head patch by time of cellularization. Fades during gastrulation. | Range from deletion of odd parasegments to formation of lawn of denticles. Also loss of labral tooth. Other alleles give extra hairs in adult. | Transcriptional regulator (helix-loop-helix domain) | Represses run, ftz; activates eve |
| paired (prd) | Transcription starts at preblastoderm stage; 8 stripes with dorsal head patch by cellularization. During germ band extension stripes 2-7 split and then fade. | Deletions about 1 segment wide starting in middle of denticle band affecting mainly odd abdominal segments | Transcriptional regulator (homeodomain) | Activates wg, en |
| runt (run) | Transcription starts at preblastoderm stage; 7 stripes. After cellularization, patter becomes single-segment stripes, which persist through germ band extension. | Deletions more than 1 segment wide centered on T2, A1, A3, A5, A7, with mirror duplication of what is left | Transcriptional regulator (novel) | Represses h, eve; activates ftz |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| engrailed (en) | Transcription starts at blastoderm stage and produces 14 narrow stripes by extended germ band stage, marking the anterior of each parasegment. Expression in posterior compartments of larval imaginal discs | Ventral cuticle a continuous lawn of denticles. Less severe alleles delete even-numbered parasegments | Transcriptional regulator (homeodomain) | Maintains hh and indirectly wg activity; selector gene defining posterior compartment |
| frizzled (fz) | Various imaginal discs | Variable orientation of wing hairs, irregular ommatidia in eye | Seven-pass transmembrane receptor | Receptor for wg |
| frizzled-2 (fz-2) | Apparently redundant with fz | |||
| hedgehog (hh) | Posterior compartments of larval segments and imaginal discs | Posterior compartment replaced with mirror image of anterior compartment | Secreted sinaling molecule (TGF-β super family) | Maintains wg and indirectly en. defines source of segmental morphogen |
| patched (ptc) | In anterior compartments | Defects in segmentation and eye development | Multipass transmembrane protein | Parto of the receptor complex for hh |
| smoothened (smo) | In anterior compartments | Defects in various tissues including epidermis, wing, and eye | G protein-associated transmembrane receptor | Part of the receptor complex for hh; causes segregation of posterior from anterior compartmente cells |
| wingless (wg) | Transcription starts at blastoderm stage and produces 14 narrow stripes by extended germ band stage, marking the posterior of each parasegment. | Ventral cuticle a continuous lawn of denticles, indicating deletion of 3/4 of each segmental unit | Secreted signaling molecule (Wnt family) | Maintains en |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| abdominal A (abd-A) | Trancribed in PS 7-13 of extended germ band | Transforms PS 7-9 to PS 6 | Transcriptional regulator (homeodomain) | Represses Ubx; activates wg, dpp; specifies a.p. body pattern |
| Abdominal B (Abd-B) | Transcribed in PS 10-14 of extended germ band | Transforms PS 10-14 to PS 9 | Transcriptional regulator (homeodomain) | Represses Ubx; specifies a.p. body pattern |
| Antennapedia (Antp) | Transcription starts in blastoderm; mainly PS 4, also in posterior parasegments. Thoracic imaginal discs. | Transforms PS4, 5 to PS 3 | Transcriptional regulator (homeodomain) | Specifies a.p. body pattern |
| Deformed (Dfd) | Transcription in preblastoderm stage in PS 1; later also PS 0. Eye-antennal disc. | Deletion of mandibular and maxillary segments | Transcriptional regulator (homeodomain) | Activates itself; specifies a.p. body pattern |
| labial (lab) | Transcription in extended germ band anterior to cephalic furrow and in posterior midgut | Deletes labial derivatives | Transcriptional regulator (homeodomain) | Specifies a.p. body pattern |
| Polycomb-group (Pc-G) | Multiple homeotic transformations | Maintains inhibition of inactive homeotic genes | ||
| Sex combs reduced (Scr) | Transcription in PS 2 in blastoderm; later PS 3 epidermis and mesoderm, and abdominal ganglia | Transforms PS3 to PS 4 and PS2 to PS1 | Transcriptional regulator (homeodomain) | Specifies a.p. body pattern |
| trithorax-group (trx-G) | Multiple homeotic transformations | Maintains inhibition of active homeotic genes | ||
| Ultrabithorax (Ubx) | Transcrition starts in cellular blastoderm, mainly in PS 6, but at lower levels in PS5-13; more in even-numbered parasegments. Neuromeres; metathoracic discs. | Transforms PS 5, 6 to PS 4 | Transcriptional regulator (homeodomain) | Represses Scr; represses Antp; activates itself; activates wg, dpp; selector gene |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| cactus (cac) | Maternal; action in embryo | Ventralizing | Genetic regulator | Inhibits entry of dl protein to nuclei |
| dorsal (dl) | Transcription in nurse cells; uniform mRNA in oocyte and egg; ventral-dorsal gradient of protein in preblastoderm nuclei | Embryos become tubes of dorsal epidermis. Some haploinsufficient alleles. | Genetic regulator | Activates twi, sna; represses zen, dpp; morphogen for dorsoventral pattern |
| easter (ea) | Maternal, released from embryo into preivitelline space | Similar to dl. Also weak ventralizing gain-of-function alleles. | Serine proteases | Activation of spz (Tl ligand) |
| gastrulation defective (gd) | Maternal, released from embryo into perivitelline space | Similar to dl | Serine protease | Activation of spz (Tl ligand) |
| gurken (grk) | Maternal; needed in oocyte | Ventralizing; affects eggshell and embryo | Growth factor-like | Ligand for top protein; dorsalizing signal from oocyte |
| nudel (ndl) | Maternal; needed in follicle cells | Similar to dl | Protease activity | Contributes to ventral polarizing activity |
| pelle (pll) | Maternal, acts in embryo | Similar to dl | Protein kinase | Signal transduction from Tl to cac |
| pipe (pip) | Maternal; needed in follicle cells | Similar to dl | Glycosaminoglycan-modifying enzyme | Localized contribution to ventral polarizing activity |
| snake (snk) | Maternal, released from embryo into perivitelline space | Similar to dl | Serine protease | Activation of spz (Tl ligand) |
| spätzle (spz) | Maternal, released from embryo into perivitelline space | Similar to dl | Ligand for Tl protein | |
| Toll (Tl) | Maternal; uniform distribution of protein in egg plasma membrane | Similar to dl. Gain-of-function alleles ventralize, producing denticle belts all around. | Receptor tyrosine kinase | Activated ventrally by spz; releases dl from cac, permits dl to enter nucleus |
| torpedo (top) | Maternal; needed in follicle cells | Similar to grk | Growth factor receptor | Receptor for grk, inhibits pip, thus orienting ventral polarizing activity. |
| tube (tube) | Maternal; acts in embryo | Similar to dl | Adapter protein | Signal transduction from Tl to cac |
| windbeutel (wbl) | Maternal; needed in follicle cells | Similar to dl | Enzyme associated with endoplasmic reticulum | Contributes to ventral polarizing activity. |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| decapentaplegic (dpp) | Transcription in preblastoderm on dorsal side, curling around to ventral at poles. (see also Compartment-Related Genes) | Loss of amnioserosa and reduction of dorsal epidermis. Viable alleles produce multiple defects in imaginal disc derivatives. | Signaling molecule (TGF-β homologue) | Forms morphogen gradient with maximum dorsally. Promotes amnioserosa and epidermis; inhibits neurogenesis |
| short gastrulation (sog) | Protein synthesized blastoderm cells in ventral | Dorsalizes embryo | Plasma membrane protein | antagonizes dpp; specifies d.v. pattern |
| snail (sna) | Transcription in mid-ventral strip of prospective mesoderm | Loss of mesoderm | Transcriptional regulator (zinc finger domain) | Inhibits expression of other d.v. patterning genes in prospective mesoderm. |
| tolloid (tld) | Released from blastoderm cells into extracellular space | Ventralizes embryo | Metalloprotease | Cleaves extracellular domain of sog, especially in presence of dpp; specifies d.v. pattern |
| twist (twi) | Transcription in mid-ventral strip of prospective mesoderm and mesectoderm | Loss of mesoderm | Transcriptional regulator (basic helix-loop-helix domain) | Specifies dorsoventral pattern |
| zerknüllt (zen) | Transcription in preblastoderm stage on dorsal side | Loss of amnioserosa and optic lobe | Transcriptional regulator (homeodomain) | Promotes amnioserosa formation |
| Gene | Expression Pattern | Mutant Phenotype | Molecular Nature | Developmental Function |
|---|---|---|---|---|
| Achaete (Ac) | Proneural cells, prospective sensory bristles | Lack of sensory bristles and neurons | Transcriptional regulator (bHLH domain) | Many functions, incl. patterning around d.v. compartment boundary in wing |
| apterous (ap) | Dorsal compartments of wing and haltere discs | Wings and halteres missing | Transcriptional regulator (homeodomain) | Required for wing (haltere) outgrowth; selector gene |
| cubitus interruptus (ci) | Anterior compartment of each segment | Disturbed segmentation | Transcriptional regulator (zinc finger domain) | Activates wg and dpp in response to hh signaling |
| decapentaplegic (dpp) | In strip of cells anterior to a.p. compartment boundary (see also Zygotic Dorsoventral Class) | Abnormal wing patterns | Secreted protein (TGF-β superfamily) | Morphogen for anteroposterior pattern of wing and haltere |
| Distalless (Dll) | Expressed around leg dorsoventral compartment boundary | Loss of legs and antennae | Transcriptional regulator (homeodomain) | Required for outgrowth of legs and antennae |
| fringe (fng) | Dorsal wing and haltere compartments | Loss of wings and halteres | Secreted protein | Juxtaposition of cells with and without fringe activates wg+ |
| hedgehog (hh) | see Zygotic Segment Polarity Class | |||
| optomotor-blind (omb) | Prospective CNS and epidermal regions | Transcriptional regulator | Target of dpp in patterning of wing and abdominal segments | |
| scute (sc) | Similar to Achaete | |||
| spalt (sal) | In endoderm and parts of wing imaginal disc | Transcriptional regulator (zinc finger domain) | Target of dpp in wing patterning | |
| vestigial (vg) | In prospective appendages of wing and haltere imaginal discs | Loss of wings and halteres | Putative transcriptional regulator | Specification of wing and haltere as opposed to thorax |
