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General Information
Symbol
Dmel\gbb1
Species
D. melanogaster
Name
FlyBase ID
FBal0092973
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
gbb-60A1
Mutagen
    Nature of the Allele
    Mutagen
    Mutations Mapped to the Genome
     
    Type
    Location
    Additional Notes
    References
    point mutation
    Nucleotide change:

    G23852867A

    Reported nucleotide change:

    G1518A

    Amino acid change:

    W371term | gbb-PA; W371term | gbb-PB

    Reported amino acid change:

    W371term

    Comment:

    TGG to TGA

    Associated Sequence Data
    DNA sequence
    Protein sequence
     
     
    Progenitor genotype
    Cytology
    Nature of the lesion
    Statement
    Reference

    Amino acid replacement: W371term.

    Coordinates as in FBrf0054935.

    Nucleotide substitution: G1518A.

    Expression Data
    Reporter Expression
    Additional Information
    Statement
    Reference
     
    Marker for
    Reflects expression of
    Reporter construct used in assay
    Human Disease Associations
    Disease Ontology (DO) Annotations
    Models Based on Experimental Evidence ( 0 )
    Disease
    Evidence
    References
    Modifiers Based on Experimental Evidence ( 0 )
    Disease
    Interaction
    References
    Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
     
    Phenotypic Data
    Phenotypic Class
    Phenotype Manifest In

    synapse & neuromuscular junction (with gbb2), with gbbUAS.cKa

    Detailed Description
    Statement
    Reference

    Mutants show loss of expression of P{FMRFa-EGFP.Tv}, a marker for the six Ap4 neurons in the developing ventral nerve cord, and loss of expression of eya, which identifies the four Ap cluster neurons.

    The amplitude of spontaneous miniature excitatory junction potentials (mEJPs) at the neuromuscular junction is not significantly different from controls in gbb1/gbb2 larvae, while the mEJP frequency is significantly decreased. There is a significant decrease in evoked EJP amplitude and in quantal content in the mutant larvae.

    gbb1/gbb2 larvae show a decrease in the number of boutons per neuromuscular junction compared to controls.

    gbb1/gbb2 larvae show defects in synaptic vesicle cycling (as assayed using uptake and unloading of the dye FM1-43), showing modest defects in endocytosis and more marked defects in exocytosis.

    gbb1/gbb2 mutant larvae have a reduced number of NMJ boutons compared to controls.

    Heterozygotes do not display defects in neuromuscular junction expansion.

    Homozygous gbb1 mutant larvae are transparent and slightly smaller compared to wild-type larvae of the same developmental stage. This transparency is primarily due to a change in opacity of the fat body. All regions of the fat body are present in gbb1 mutant larvae, however, the size of individual cells is reduced such that the entire organ is somewhat smaller in overall size.

    Late third instar gbb1/gbb3 mutant wing imaginal discs are 50% smaller in overall area compared to the area of wild-type wing discs of the same developmental stage.

    gbb1/gbb3 mutant larvae do not show a significant difference in overall protein levels compared to wild-type third instar larvae when normalised for body mass.

    Homozygous gbb1 third instar larvae have lower levels of lipids, triacylglycerides and short-chain fatty acids compared to wild-type larvae.

    gbb1/gbb3 mutant third instar larvae have lower levels of glucose and trehalose levels than wild-type controls.

    gbb1/gbb3 mutant third instar larvae show increased uptake and transport of ingested fluorescently labeled fatty acids from the midgut lumen to the fat body compared to wild-type controls.

    gbb1 homozygous mutants exhibit significantly reduced synaptic currents in aCC/RP2 compared with heterozygous controls.

    Large double-sided gbb1 clones in the anterior compartment of the wing lead to non-autonomous defects in the posterior compartment. These clones show a narrowing of the L4-L5 intervein and a truncation of wing vein L5. Wings containing both large anterior and posterior gbb1 clones exhibit a more severe patterning defect than a clone in either compartment alone, including a complete loss of L5 and defects in L4 specification.

    The wings of gbb1/gbb4 flies show a loss of the L4-L5 intervein and a truncation of wing vein L5.

    gbb1 clones induced in the anterior of the wing produces defects in the specification of the L4-L5 intervein and the L5 vein.

    The evoked synaptic current amplitude recorded in aCC/RP2 neurons is significantly smaller in gbb1 homozygotes compared with heterozygous controls.

    gbb1/gbb4 mutants exhibit a slight but consistent reduction in neurotransmitter release (measured by intracellular recordings from muscle 6 of segment A3). These mutants also show a small reduction in synaptic bouton number. Gross synaptic ultrastructure (examined in 3rd instar larval muscles 6 & 7) appears normal apart from a small population of large vesicles distinct from and unlike synaptic vesicles, and occasional aberrant cytoplasmic electron-dense structures ('T-bodies') that can cluster synaptic vesicles. In the active zones of gbb1/gbb4 mutants there are intermittent detachments between pre- and postsynaptic membranes. Mutant boutons are approximately the same size as wild-type boutons but the bouton surface area per active zone is increased. However, the bouton surface area per T bar is decreased compared to wild-type. The wings of gbb1/gbb4 adults lack a posterior crossvein, and have a truncated L5 vein. Very few gbb1/gbb2 animals survive to the 3rd instar larval stage. Synapse size and bouton density are greatly reduced at neuromuscular junctions in gbb1/gbb2; P{UAS-gbb.K}9.9 larvae compared to wild-type. There is a severe decrease in the amplitude of evoked excitatory junctional potentials (EJP) in this mutant combination when compared to wild-type. The mutants also show a small increase in mini-EJP amplitude and a reduction in the frequency of spontaneous release when compared to wild-type. Measurements of quantal content of these mutant synapses shows that they release 4-fold less neurotransmitter than wild-type synapses.

    gbb1/gbb4 males raised at 18oC have significantly smaller testes than normal, with a dramatic reduction in the number of germ cells of all stages, particularly germ line stem cells, spermatogonia and spermatocytes. In the most extreme cases, germ line stem cells, spermatogonia and spermatocytes are completely missing.

    gbb1/gbb4 adults lack the posterior crossvein (PCV) and the distal tips of veins L4 and L5. The overall size of the wing is reduced compared to wild type. Homozygous clones in the wing disc show the same size, distribution and frequency as control wild-type clones. Mutant phenotypes are only observed in clones or regions of clones where both the dorsal and ventral surfaces of the wing are mutant (referred to as "double-sided" clones). Double-sided clones that occupy the entire posterior compartment of the wing show loss of the PCV and loss of the distal quarter of vein L5. Smaller clones covering either just the PCV or distal tip of L5 also show loss of the corresponding vein structures. In double-sided clones that cover only the anterior or posterior half of the PCV, the vein is absent in the mutant cells and stops either precisely at the boundary of the dorsoventral overlap or within 2 to 3 cells of it. The PCV can stop on either the wild-type or the mutant side of the clone boundary. This partial loss of the PCV is only seen if the double-sided clone includes at least one of the two junctions of the PCV with the longitudinal veins. Double-sided clones that fall within the distal quarter of L5 show loss of the vein only within mutant tissue, with the vein stopping within 2 to 3 cells of the dorsoventral overlap of the clone. The distal tip of L5 can also be missing in cases where clones cover the proximal part of L5, even if the distal quarter of L5 is wild-type (on either ventral, dorsal or both surfaces). Double-sided clones that cover the entire posterior compartment of the wing have little or no effect on vein L4. Loss of L4 is seen when double-sided clones cover the region both anterior and posterior to the vein. Double-sided clones that cover the entire anterior compartment of the wing have no defects in the costal vein or veins L1, L2 or L3. These clones are associated with a reduction in overall size of the wing blade (both the anterior and posterior compartments show a reduction in size) and loss of all but the most proximal portion of vein L5. The truncation of L5 is somewhat variable and may or may not be accompanied by the loss of the PCV. Double-sided clones that cover the region between veins L1 and L3, or the region between L3 and L4 (but not including L3) are normal in size and patterning. Double-sided clones with an anterior border in the intervein region between L2 and L3 and a posterior border running the length of the A/P compartment boundary show the mutant phenotypes seen in clones occupying the whole anterior compartment.

    gbb1/gbb4 flies show wing vein truncations.

    Less than 10% of mutants dies as embryos. Females with homozygous gbb1 germ line clones produce phenotypically wild type eggs that hatch and survive to adulthood. Mutant larvae are lethargic and flaccid. Imaginal discs are dramatically reduced. Fat body morphology is abnormal, giving rise to transparent phenotype. Cuticle exhibits defects in the telson region. In severe cases posterior spiracles do not protrude from the larval bosy and the stigmatophores are partially fused and more dorsally situated. In embryogenesis, formation of the anterior midgut constriction starts but fails to reach completion, giving rise to a bulbous anterior midgut. The position of the other constrictions is shifted. Mutants fail to extend the gastric caecae by stage 17. The eyes of gbb1/gbb4 are reduced in size with 10-20% ommatidia fewer than wild type. Loss of ommatidia is restricted to the ventral portion of the eye. gbb1/gbb4 show extra scutellar and dorsocentral bristles. Ectopic scutellars most often occur in close proximity to the endogenous bristle, but sometimes between the anterior and posterior scutellar bristles.

    Less than 5% of gbb1/gbb4 flies survive to adulthood at 25oC. Escapers show a reduction of wing veins L4 and L5 and lack the posterior crossvein.

    Homozygous embryos show defects in gut morphogenesis and die as early larvae. gbb1/gbb4 animals generally die as larvae, with rare adult escapers (less than 1%). The larvae appear transparent, due to a defect both in the quantity and quality of the fat body, and a dramatic reduction in imaginal tissues. Areas of the brain are also reduced. The larvae develop more slowly than wild-type and never attain wild-type size. Adult escapers have small, misshapen wings, which lack the posterior crossvein, much of wing vein L5, distal portions of vein L4 and the posterior half of the anterior crossvein. There is a loss of intervein material, especially between veins L2 and L3, between L4 and L5 and posterior to L5, resulting in narrow, pointed wings. Thinning of vein L2 and some ectopic vein material in the intervein region flanking vein L2 is common. No abnormalities in position or type of wing bristles are seen along the wing margin, although ectopic margin bristles are often seen along a vein or in intervein tissue in distal regions of the wing. The eyes are smaller than normal and have supernumerary vibrissae, there is an increase in the number of thoracic bristles, and leg segments may be misshapen. Female sterility is also seen. Homozygous clones are not recovered in the wing if the clones are induced before 36 hours after egg laying. Clones in the wing are recovered if they are induced later. Clones located in both the anterior and posterior compartments, as well as clones limited to the posterior compartment, show defects in wing pattern elements, including loss of the posterior crossvein, loss of portions of veins L4 and L5, and loss of the distal part of vein L3 at the wing margin. 80% of these clones that show a mutant phenotype cover a portion of the wing where vein material is normally located. Clones strictly limited to the anterior compartment or along the anterior/posterior (A/P) boundary show no wing defects, with the exception of very small clones located near the anterior crossvein, which result in ectopic vein material anterior to vein L3. Wing vein loss is sometimes seen in wild-type tissue at a distance from the clone in wings containing multiple clones; one in the posterior compartment and another along the A/P boundary.

    External Data
    Interactions
    Show genetic interaction network for Enhancers & Suppressors
    Phenotypic Class
    NOT Enhanced by
    Statement
    Reference

    gbb2/gbb1 has neuroanatomy defective phenotype, non-enhanceable by Neto[+]/Neto36

    gbb1 has lethal | recessive phenotype, non-enhanceable by lilliunspecified

    Suppressed by
    NOT suppressed by
    Statement
    Reference

    gbb4/gbb1 has visible phenotype, non-suppressible by sax1/scwgbb.PF/sax2

    Enhancer of
    Statement
    Reference

    gbb1/gbb[+] is an enhancer of visible phenotype of dppd5/dpphr56

    gbb1/gbb[+] is an enhancer of visible | dominant phenotype of sogEP7

    gbb1 is an enhancer of visible | recessive phenotype of tkv427

    NOT Enhancer of
    Statement
    Reference

    gbb1/gbb[+] is a non-enhancer of neurophysiology defective phenotype of DysDp186.166.3

    gbb1/gbb[+] is a non-enhancer of visible | dominant phenotype of sogEP11

    Suppressor of
    Statement
    Reference
    NOT Suppressor of
    Statement
    Reference
    Other
    Phenotype Manifest In
    Enhanced by
    Statement
    Reference

    gbb1 has crossvein | somatic clone phenotype, enhanceable by dppd12/dpp[+]

    gbb1 has wing vein L5 phenotype, enhanceable by dppd12

    gbb1 has wing cell phenotype, enhanceable by dppd12

    gbb1 has submarginal cell phenotype, enhanceable by dppd12

    gbb1 has 2nd posterior cell phenotype, enhanceable by dppd12

    gbb1 has discal cell phenotype, enhanceable by dppd12

    gbb1 has wing basal cell 2 phenotype, enhanceable by dppd12

    gbb1 has anterior crossvein phenotype, enhanceable by dppd12

    gbb1 has wing phenotype, enhanceable by Df(2L)tkv2

    gbb1 has wing vein L4 phenotype, enhanceable by dppd12

    gbb1 has wing vein L2 phenotype, enhanceable by dppd12

    gbb1 has wing vein L3 phenotype, enhanceable by dppd12

    NOT Enhanced by
    Statement
    Reference

    gbb2/gbb1 has terminal bouton phenotype, non-enhanceable by Neto[+]/Neto36

    gbb1 has wing vein L5 | somatic clone phenotype, non-enhanceable by dppd12/dpp[+]

    gbb1 has crossvein | somatic clone phenotype, non-enhanceable by dpps4/dpp[+]

    gbb1 has wing vein L5 | somatic clone phenotype, non-enhanceable by dpps4/dpp[+]

    Suppressed by
    Statement
    Reference

    gbb4/gbb1 has wing vein phenotype, suppressible by Agam\gbb1gbb.PF

    gbb4/gbb1 has wing vein phenotype, suppressible by Agam\gbb2gbb.PF

    NOT suppressed by
    Statement
    Reference

    gbb4/gbb1 has wing vein phenotype, non-suppressible by sax1/scwgbb.PF/sax2

    Enhancer of
    Statement
    Reference

    gbb1/gbb[+] is an enhancer of crossvein phenotype of dppd5/dpphr56

    gbb1/gbb[+] is an enhancer of wing vein L2 phenotype of dppd5/dpphr56

    gbb1/gbb[+] is an enhancer of wing vein L2 phenotype of dppd5/dpphr4

    gbb1/gbb[+] is an enhancer of wing vein phenotype of sogEP7

    gbb1 is an enhancer of wing vein phenotype of tkv427

    NOT Enhancer of
    Statement
    Reference

    gbb1/gbb[+] is a non-enhancer of wing vein phenotype of sogEP11

    Suppressor of
    Other
    Additional Comments
    Genetic Interactions
    Statement
    Reference

    Syx473/+;gbb1/+ double heterozygotic third instar larvae do not show significant differences in bouton number at the neuromuscular junction compared to wild type or single heterozygotes.

    The ability of gbbScer\UAS.cKa expressed under the control of Scer\GAL4Toll-6-D42 to rescue the electrophysiological defects seen at the neuromuscular junction in gbb1/gbb2 larvae is impaired but not completely abolished if the larvae are also homozygous for cmpyΔ8.

    One copy of Neto36 does not enhance the reduction in NMJ bouton number seen in gbb1/gbb2 mutant larvae.

    Larvae that are heterozygous for both Neto36 and gbb1 have smaller NMJs with 30% fewer synaptic boutons than controls.

    The increase in bouton number at the neuromuscular junction which is seen in third instar larvae expressing mavScer\UAS.T:Avic\GFP under the control of Scer\GAL4Gli-rL82 is completely suppressed by gbb1/+.

    The neuromuscular junction expansion phenotype seen in cmpyΔ8 mutants is partially suppressed when animals are also heterozygous for gbb1.

    scwgbb.PF cannot rescue the wing vein defects of gbb1/gbb4 flies in a sax1/sax2 background.

    RhoGAP92B1/+ gbb1/+ double heterozygous third instar larvae show a significant decrease in bouton number/muscle area and satellite bouton number at the neuromuscular junction compared to wild type.

    Only 15% of MAN1ΔC flies heterozygous for gbb1 show extra venation.

    In a gbb1 heterozygous mutant, with only one copy of wild-type gbb, the absence of Dp186 through a DysDp186.166.3 homozygous background is sufficient to increase synaptic currents to a level comparable to that observed in DysDp186.166.3 mutants with wild-type levels of gbb expression.

    Double homozygous gbb1; DysDp186.166.3 mutants display increased synaptic currents relative to gbb1 mutants.

    A gbb1 heterozygous or homozygous background has no effect on the increase in synaptic current amplitude found upon expression of DysDp186.Scer\UAS post-synaptically under the control of Scer\GAL4eve.RN2.

    spictmut neuromuscular junction overgrowth phenotypes are fully suppressed in gbb1/gbb4 mutants. The synaptic undergrowth phenotypes in larvae homozygous for spictmut in a gbb1/gbb4 background are indistinguishable from that of gbb1/gbb4 mutants alone. In addition, a heterozygous gbb1 background partially suppresses the neuromuscular junction expansion of spictmut larvae.

    gbb1, dppd12/+ clones induced in the anterior of the wing leads to a greater loss of the L4-L5 intervein than gbb1 clones but no greater loss of the L5 wing vein.

    gbb1, dpps4/+ clones induced in the anterior of the wing show no enhancement of the wing vein phenotypes caused by gbb1 clones.

    dppd5/dpphr56, gbb1/+ flies show an enhancement of the dppd5/dpphr56 wing phenotype; there is an increase in the fraction of wings with L2 or L4 defects and/or a more severe reduction of the L4-L5 intervein.

    Expression of rutScer\UAS.cZa under the control of Scer\GAL4eve.RN2 fails to potentiate synaptic current amplitude in a gbb1 background.

    Dp(2;2)B16, Dp(2;2)DTD48 or Dp(2;2)B16/Dp(2;2)DTD48 cannot rescue gbb1 homozygotes to adulthood, but there is a dramatic rescue of larval lethality to pupal/pharate adult lethality.

    The gbb1/gbb4 phenotype is dominantly enhanced by dppd12; there is a greater loss of wing vein L4, wing vein L2 and the anterior crossvein than in gbb single mutant flies. There is also loss of intervein tissue, especially between veins L2 and L3 and between veins L4 and L5, resulting in a reduction in the size of the wing. A gap at the distal end of vein L3 is seen in 3% of cases. A reduction in the loss of wing vein L5 is seen in these flies. Viability is reduced. Flies show truncations and/or fusions of the distal-most tarsal segments of the male prothoracic leg. Wings derived from dppd6/dpps4 animals lack only the anterior crossvein. The anterior crossvein is restored in dppd6/dpps4 flies carrying one copy of gbb1. The wing is reduced in size in these animals and viability is significantly reduced. Addition of Df(2L)tkv2 into gbb1/gbb4 flies results in a more severe wing phenotype but less severe lethality. tkv427/Df(2L)tkv2 flies show slight thickening of the wing veins. This phenotype is enhanced by gbb1. The viability of gbb1/gbb4 flies is dominantly reduced by sax4 or sax5.

    Xenogenetic Interactions
    Statement
    Reference

    Agam\gbb1gbb.PF and Agam\gbb2gbb.PF each completely rescue the wing vein defects of gbb1/gbb4 animals.

    Agam\gbb1gbb.PF and Agam\gbb2gbb.PF each partially rescue the wing vein defects of gbb1/gbb4 animals in a sax1/sax2 background; partial rescue of the posterior crossvein is seen and in addition loss of the distal tips of vein L5 and loss of the distal quarter of vein L4 are seen.

    Complementation and Rescue Data
    Partially rescued by
    Not rescued by
    Comments

    Expression of gbbScer\UAS.cKa under the control of Scer\GAL4Toll-6-D42 rescues the reduction in spontaneous miniature excitatory junction potential frequency, evoked excitatory junction potential amplitude and quantal content which is seen at the neuromuscular junction in gbb1/gbb2 larvae.

    The presence of gbbt.mNS partially rescues the lethality associated with gbb1 mutants, with 60% of embryos surviving to adulthood. These flies exhibit defective wings.

    The presence of gbbt.mS1 partially rescues the lethality associated with gbb1 mutants, with 7.4% of embryos surviving to adulthood. These flies exhibit defective wings. Wings from adult survivors show blistered and ectopic venation phenotypes.

    The presence of P{UAS-gbb.K}9.9 alone (in the absence of any driver) can rescue survival of gbb1/gbb2 animals to 3rd instar or pupal stage. The additional presence of Scer\GAL4G14 rescues bouton density and spontaneous mini-EJP (excitatory junctional potential) frequency to wild-type levels, and partially rescues spontaneous mini-EJP amplitude, evoked EJP frequency and levels of neurotransmitter release at synapses. Essentially identical results are seen when Scer\GAL4BG380 is used instead (although bouton density not measured). However, when Scer\GAL4elav-C155 is used there is only a slight rescue of bouton density, but the frequency and amplitude of spontaneous mini-EJPs, the amplitude of evoked EJPs and the levels of neurotransmitter release at synapses are all rescued to wild-type levels.

    Images (0)
    Mutant
    Wild-type
    Stocks (0)
    Notes on Origin
    Discoverer
    Comments
    Comments

    Homozygotes and hemizygotes over Df(2R)b23 are phenotypically indistinguishable. The gbb alleles fall into a phenotypic series. Starting with the most severe alleles: gbb1 = gbb2 > gbb3 > gbb4.

    External Crossreferences and Linkouts ( 0 )
    Synonyms and Secondary IDs (3)
    References (38)