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General Information
Symbol
Dmel\sn3
Species
D. melanogaster
Name
FlyBase ID
FBal0015773
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Allele class
Mutagen
Nature of the Allele
Allele class
Mutations Mapped to the Genome
 
Type
Location
Additional Notes
References
Associated Sequence Data
DNA sequence
Protein sequence
 
 
Progenitor genotype
Cytology
Nature of the lesion
Statement
Reference

0.3kb deletion from 1184bp to 1475bp of the wild-type sequence. This deletion is in the 5' end of the gene, and the coding region is intact.

Carried on aberration
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
Detailed Description
Statement
Reference

The number and density of spiked protrusions on the dendrites of class III ldaB neurons is reduced in mutant third instar larvae compared to wild type, while the total branch length of the dendritic tree is normal. The fraction of spiked protrusions that exceed 10 μm in length is increased in the mutant larvae.

Sensory bristles are gnarled and wavy in sn3 adults.

sn3 mutants exhibit a normal looking ellipsoid body.

The cuticles of sn3 mutants show thin, crooked, abnormal denticles.

Neurons cultured from sn3/sn3 brains have a distinctive abnormal morphology. Axons curl, creating a filagree pattern. Filamentous axon distribution within these neurons is abnormal.

The wing hairs of sn3 mutants show a 12-14% reduction in length compared to wild-type hairs. Few actin bundles are present in transverse or longitudinal sections taken through sn3 hairs; rather, the actin filaments are present in an almost diffuse cortical layer.

The bristles of sn3 mutants are twisted; bristles can twist either to the right, to the left, or first in one direction and then the other. These mutant bristles have large gaps between flutes, reflecting abnormal distribution of the actin bundles. Apart from where twisting occurs, the curvature of sn3 bristles is similar to wild type. Additionally, sn3 mutant bristles lie flat over the surface of the thorax, instead of pointing away from the thorax, as in wild type.

sn3 adults exhibit bent and twisted bristles of normal length. This phenotype is more pronounced in macrochaetes than microchaetes. Each macrochaete flute is not equally spaced nor equal in size and is twisted. Particularly in the lower half of the bristle, a honeycomb of short ridges 5-10υm in length is found, most of which is connected to a major longitudinal ridge. Overall, the ridges and valleys have a collective longitudinal orientation and continuous ridges of over 50υm in length and are common on most bristles, especially near the tip.

The longitudinal actin bundles of wild-type bristle cells are composed of a hexagonally-packed array of actin filaments that form a triangular shape at the plasma membrane. sn3 mutants lack the fascin cross-bridges that usually form between actin filaments within a bundle. The longitudinal bundles of sn3 bristle cells contain fewer filaments than wild type; these filaments are liquid ordered not hexagonally-packed. These defects cause the bundles to form a rectangular shape that does not extend as far into the cytoplasm as the wild-type triangular bundle.

The arista laterals are shorter than normal and weakly curved in mutant flies.

Actin bundles in the bristles of heterozygous flies are comparable in number and size to wild type and the area occupied by the filaments is not significantly different from wild type. The filaments are hexagonally packed. The bristles are the same length as in wild-type flies. Bristles of homozygotes are shorter than wild type.

Strong bristle phenotype.

Mutation causes a severe denticle phenotype. Denticles tend to be smaller and have thinner hooks than wild-type denticles. They are also less orderly along each row and sometimes have a floppy appearance.

Actin bundles are twisted in sn3 bristles.

Macrochaetae are bent, gnarled, twisted and considerably shorter than in wild-type flies. Microchaetae are often irregularly bent, and are shorter and less rigid than in wild-type flies. The ridges and valleys on the surface of the microchaetae are distorted. Actin bundles within the bristle cells are smaller and flatter than normal, and the filaments within them are disordered.

Bristles are gnarled due to disrupted actin filament bundles.

Extreme bristle phenotype.

Extreme bristle phenotype, female fertile.

sn68/sn3 females have a sn mutant phenotype and are fertile.

class 3 - female fertile with gnarled macrochaetae and kinky microchaetae

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

sn3 is a non-enhancer of optomotor response defective phenotype of ebo678

NOT Suppressor of
Statement
Reference

sn3 is a non-suppressor of optomotor response defective phenotype of ebo678

Other
Statement
Reference
Phenotype Manifest In
Enhanced by
Statement
Reference

m1, sn3 has denticle phenotype, enhanceable by f36a

f36a, m1, sn3 has denticle phenotype, enhanceable by shaV15

f36a, m1, sn3 has denticle phenotype, enhanceable by WASp3

sn3 has denticle phenotype, enhanceable by m1

sn3 has microchaeta phenotype, enhanceable by f36a

sn3 has macrochaeta phenotype, enhanceable by f36a

sn3 has microchaeta & actin filament phenotype, enhanceable by f36a

NOT Enhanced by
Statement
Reference

sn3 has arista phenotype, non-enhanceable by f36a

NOT suppressed by
Statement
Reference

sn3 has arista phenotype, non-suppressible by f36a

sn3 has phenotype, non-suppressible by su(Hw)2

Enhancer of
Statement
Reference

sn3 is an enhancer of denticle phenotype of f36a, m1

sn3 is an enhancer of denticle phenotype of m1

sn3 is an enhancer of microchaeta phenotype of f36a

sn3 is an enhancer of macrochaeta phenotype of f36a

sn3 is an enhancer of microchaeta & actin filament phenotype of f36a

NOT Enhancer of
Statement
Reference

sn3 is a non-enhancer of ellipsoid body phenotype of ebo678

sn3 is a non-enhancer of fan-shaped body phenotype of ebo678

sn3 is a non-enhancer of arista phenotype of f36a

NOT Suppressor of
Statement
Reference

sn3 is a non-suppressor of ellipsoid body phenotype of ebo678

sn3 is a non-suppressor of fan-shaped body phenotype of ebo678

sn3 is a non-suppressor of arista phenotype of f36a

Other
Additional Comments
Genetic Interactions
Statement
Reference

In f36a sn3 double homozygous embryos, tracheal actin rings are formed properly similar to controls.

ebo678 sn3 double mutants exhibit differences in the appearance of the ellipsoid and fan-shaped bodies, compared to wild-type and exhibit behavioral defects as found in ebo678 single mutants. The ellipsoid body defect is clearly visible in 100% of the animals but is more variable, ranging from just open at the bottom, to totally dissociated into two lumps of neuropil.

No correlation is observed between the severity of the structural and behavioral defects in ebo678 sn3 gynandromorphs. Of those gynandromorphs in which the central complex can be distinguished, roughly half exhibit abnormal ellipsoid bodies and behavioral defects. Mutant yaw torque activity and torque spike frequency is found in about 39% and 64% of ebo678 sn3 gynandromorphs.

The denticles of m1, sn3 mutants show splitting in addition to the defects seen in either single mutant. sn3, m1, f36a triple mutants have small, highly misshapen denticles that are more affected than those of m1, f36a or m1, sn3 double mutants. sn3, m1, f36a; shaV15 and sn3, m1, f36a; WASp3 quadruple mutants show further impairment to denticle formation compared to sn3, m1, f36a triple mutants, with mutants exhibiting regions of naked cuticle where denticles lie in wild-type animals.

The dorsal hairs on the abdominal segments of sn3, m1, f36a triple mutants are severly reduced in size, and in some cases, hairs are abrogated leaving abnormal naked regions. This phenotype is more severe in sn3, m1, f36a; WASp3 quadruple mutants and is even more severe in sn3, m1, f36a; shaV15 mutants in which most dorsal hairs are absent, leaving naked cuticle.

sn3, f36a double mutants have bristles that are short, like f36a mutants, and twisted, like sn3 mutants.

In f36a sn3 double mutants, bristle ridges of length more than 10υm (45% of wild-type length) are not found. Instead, a variety of short ridges 3-10υm in length are found. Some of these are parallel to the longitudinal axis of the bristle, whereas others are perpendicular or oblique. These ridges are seldom connected to one another but terminate freely on the surface.

In f36a, sn3 double mutants, bristle cells contain tiny rafts of membrane-attached actin filament clusters, which consist of a monolayer of filament. This is a more extreme phenotype than that observed with either of the single mutants. When these f36a, sn3 mutant cells are treated with jasplakinolide, large clusters of actin filaments appear internally, most of which run parallel to the longitudinal axis of the bristle. These clusters have an irregular shape and have a liquid ordered packing of filaments, instead of wild-type hexagonal packing.

sn3 f36a double mutants have ocellar bristles which are shorter and have a smaller volume than normal.

The arista lateral phenotype of sn3 f36a double mutants is not substantially stronger than either single mutant. Double mutant arista laterals are thinner than wild type. At a low frequency, branched laterals are seen. The mutant laterals start to extend at the normal time, but their rate of extension is slower than normal.

Only 2% of postvertical bristles are split in sn3 f36a flies. The frequency of split bristles is increased by injection of cytochalasin D. Bristle elongation in sn3 f36a flies is more sensitive to vinblastine than in wild-type flies.

Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Not rescued by
Comments

Scer\GAL4hs.PB-driven expression of snScer\UAS.P\T.T:Avic\GFP-EGFP fully rescues the gnarled bristle phenotype exhibited by sn3 mutants.

Scer\GAL4hs.PB-driven expression of snS52A.Scer\UAS.P\T.T:Avic\GFP-EGFP fully rescues the gnarled bristle phenotype exhibited by sn3 mutants.

Scer\GAL4hs.PB-driven expression of snS52E.Scer\UAS.P\T.T:Avic\GFP-EGFP fails to rescue the gnarled bristle phenotype exhibited by sn3 mutants.

Images (1)
Stocks (92)
Notes on Origin
Discoverer

Mohr, 11th June 1922.

External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (2)
References (38)