Allele Dmel\Fmr1^Δ83M

General Information
Symbol	Dmel\Fmr1^Δ83M	Species	D. melanogaster
Name		FlyBase ID	FBal0131032
Feature type	allele	Created / Updated	2006-08-22/2006-08-22
Associated gene	Dmel\Fmr1

Allele class	amorph, loss of function
Mutagen	Δ2-3
Nature of the Allele
Allele class	amorph (Morales et al., 2002) loss of function (Zhang et al., 2001)
Mutagen	Δ2-3 (Zhang et al., 2001)
Mapped Features and Mutations
Type Symbol & Location Additional Notes References
Associated Sequence Data
DDBJ / EMBL / GenBank	DNA sequence Protein sequence Name

UniProtKB/Swiss-Prot
UniProtKB/TrEMBL

Progenitor genotype	Fmr1^EP3517 (Zhang et al., 2001)
Nature of the lesion	Statement Reference Deletion removing P{EP} and flanking DNA including three 5' non coding exons of the Fmr1 gene. (Zhang et al., 2001)
Assay mode
Cytology
Phenotypic Data
Phenotypic Class
	viable (Zhang et al., 2001) lethal \| partially \| pharate adult stage (Morales et al., 2002) neuroanatomy defective (Michel et al., 2004) neuroanatomy defective (with Df(3R)by62) (Michel et al., 2004) neuroanatomy defective (with Fmr1^Δ113M) (Morales et al., 2002, Michel et al., 2004) neuroanatomy defective (with Fmr1³) (Michel et al., 2004)
Phenotype Manifest In
	beta-lobe (Michel et al., 2004) alpha-lobe (Michel et al., 2004) mushroom body (Michel et al., 2004) ventral adult lateral neuron (with Fmr1^Δ113M) (Morales et al., 2002) dorsal cluster neuron (with Fmr1^Δ113M) (Morales et al., 2002) beta-lobe (with Fmr1^Δ113M) (Michel et al., 2004) alpha-lobe (with Fmr1^Δ113M) (Michel et al., 2004) mushroom body (with Fmr1^Δ113M) (Michel et al., 2004) beta-lobe (with Fmr1³) (Michel et al., 2004) alpha-lobe (with Fmr1³) (Michel et al., 2004) mushroom body (with Fmr1³) (Michel et al., 2004) beta-lobe (with Df(3R)by62) (Michel et al., 2004) alpha-lobe (with Df(3R)by62) (Michel et al., 2004) mushroom body (with Df(3R)by62) (Michel et al., 2004)
Detailed Description
	Statement Reference Mutants show a fibre extension defect in the DC and LNv neurons. Extension of DC axons from the lobula to the medulla is incomplete, some axons show guidance errors. LNv neurons may over extend, show guidance defects or show aberrant morphology. The LVn defects are less consistent than those in the DC neurons. Homozygotes show only 36.4% of expected eclosion from pupal case. The photoreceptor field in the optic lobes shows no anatomical defects. Analysis of photoreceptor synaptic transmission using ERGs revealed no alteration in either on transient or off transient; this result is contrary to that reported in FBrf0141416, where inappropriate genetic controls were used. (Morales et al., 2002) Mutants show no morphological defects. When tested for bang sensitivity, temperature sensitivity and phototaxis there is no detectable difference between wild type and mutant. (Zhang et al., 2001) Fmr1[Δ83M] mutant mushroom bodies show β-lobe fibers extending across the midline, sometimes sufficient to cause apparaent fusion of the right and left lobes. Fmr1[Δ83M] mutant γ-lobe fibers do not extend across the brain midline. γ-neurons in Fmr1[Δ83M] homozygous mutant mushroom bodies do not cross the midline. Retraction of vertical and medial branches of γ-neurons occurs on schedule and to its full extent in young mutant pupae. Given the normal midline phenotype of mutant larval and young pupal γ neurons, the late-stage β-lobe midline-crossing phenotype cannot be blamed on faulty γ-neuron morphology earlier in development. In homozygous Fmr1[Δ83M] mutant brains, the α and β lobes appear as thin Fas2-immunoreactive bundles at head eversion + 16-17 hours, with progressive thickening over the next 30 hours. The medial tips of the β lobes approach the midline at the correct time, but immediately thereafter, fibers can be seen to extend from the β-lobe termini across the midline. By 48 hours, the right and left β lobes appear fused and very similar to the pharate-adult mutant phenotype. Thus, the midline-crossing phenotype is attributable to β-lobe axons failing to stop at the normal lobe terminus and, instead, grow across the brain midline into the contralateral β-lobe. Consistent with the pharate adult, the phenotype usually develops symmetrically. Homozygous Fmr1[Δ83M] mutants exhibit misdirected or missing α-lobes in almost 30% of cases. Approximately 95% of transheterozygous Fmr1[Δ83M]/Fmr1[Δ113M] mutants exhibit severe midline crossing in the β-lobe of the mushroom body (defined as a densely strained band equal to or greater in width and thickness than those of the adjacent β-lobes). The rest appear phenotypically normal. No sexual dimorphism in penetrance or expressivity is found. Slightly over 85% of transheterozygous Fmr1[Δ83M]/Fmr1[3] mutants exhibit severe midline crossing in the β-lobe of the mushroom body (defined as a densely strained band equal to or greater in width and thickness than those of the adjacent β-lobes). Approximately 5% exhibit moderate midline crossing (defined as when the thickness of the fiber bundle crossing the midline is considerable but less than the width of the β-lobe termini), with another 5% exhibiting mild midline crossing (defined as when a thin band of fibers cross the midline). No sexual dimorphism in penetrance or expressivity is found. Fmr1[Δ83M] heterozygotes do not exhibit midline crossing in the mushroom bodies. In fewer than 10% of cases, transheterozygous Fmr1[Δ83M]/Fmr1[3] mutants exhibit misdirected or missing α-lobes. In over 25% of cases, transheterozygous Fmr1[Δ83M]/Fmr1[Δ113M] mutants exhibit misdirected or missing α-lobes. Approximately 8% of Fmr1[Δ83M]/Df(3R)by62 mushroom bodies exhibit a mild or moderate β lobe midline-crossing phenotype. One third of Fmr1[Δ83M]/Df(3R)by62 mushroom bodies display accessory phenotypes, where the α lobe is misdirected or missing. In Fmr1[Δ83M]/Df(3R)by62 pharate adults, the α and β lobes appear very immature, resembling those seen in wild-type brains at earlier stages of metamorphosis. In many cases, the lobes appear younger than those of pupae whose β lobe fibers are just approaching the midline. The mushroom body α/β immaturity phenotype is characterised by abnormally thin α and β lobes that are very irregular along their lengths, whereas the γ lobes appear normal. Approximately 80-90% of Fmr1[Δ83M]/Df(3R)by62 brains show α/β immaturity. In contrast, all Fmr1[Δ83M]/In(3LR)TM6B siblings are within normal limits. (Michel et al., 2004)
Interactions
Phenotypic Class
Phenotype Manifest In
Additional Comments
Genetic Interactions
Statement Reference
Xenogenetic Interactions
Statement Reference
Complementation & Rescue Data
Rescued by	Fmr1^Δ83M/Fmr1³ is rescued by Fmr1^+t14 (Michel et al., 2004)
Comments	The presence of a single copy of Fmr1[+t14] to Fmr1[3]/Fmr1[Δ83M] transheterozygotes greatly reduces the penetrance and expressivity of the β-lobe midline-crossing phenotype. However this does not affect the α lobe misdirecting or missing phenotype. (Michel et al., 2004)
Stocks ( 0 )

Notes on Origin
Discoverer

Synonyms & Secondary IDs ( 3 )
Reported As
Symbol Synonym	dfxr^83M (Zhang et al., 2004) Fmr1^Δ83 (Morales et al., 2002, Michel et al., 2004) Fmr1^Δ83M
Name Synonym
Secondary FlyBase IDs

References ( 4 )
Research paper	Michel et al., 2004, J. Neurosci. 24(25): 5798--5809 Defective neuronal development in the mushroom bodies of Drosophila Fragile X Mental Retardation 1 Mutants. [FBrf0179339] Zhang et al., 2004, Dev. Biol. 270(2): 290--307 The Drosophila fragile X-related gene regulates axoneme differentiation during spermatogenesis. [FBrf0178963] Morales et al., 2002, Neuron 34(6): 961--972 Drosophila Fragile X protein, DFXR, regulates neuronal morphology and function in the brain. [FBrf0149142] Zhang et al., 2001, Cell 107(5): 591--603 Drosophila fragile X-related gene regulates the MAP1B homolog Futsch to control synaptic structure and function. [FBrf0141416]

Allele Dmel\Fmr1Δ83M

Allele Dmel\Fmr1^Δ83M