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Allele Dmel\lea^robo2-8

General Information
Symbol	Dmel\learobo2-8	Species	D. melanogaster
Name		FlyBase ID	FBal0121555
Feature type	allele	Associated gene	Dmel\lea
Also Known As	robo28
Map ( GBrowse )
Allele class	loss of function allele
Mutagen	ethyl methanesulfonate
Recent Updates
Description	What does this section display? This section contains items that were added to this record for each release. It currently only tracks new links between this FlyBase report and other FlyBase data classes (e.g. genes, references, stocks) or controlled vocabulary terms (e.g. GO, anatomy terms). What does this section not display? This section does not currently display links that were removed or gene model changes.
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FB2013_03
FB2013_02
All updates	Click here to see a list of all updates to this record from FB2010_08 and on.
Nature of the Allele
Allele class	loss of function allele (Rajagopalan et al., 2000, Sano et al., 2005)
Mutagen	ethyl methanesulfonate (Rajagopalan et al., 2000)
Mutations Mapped to the Genome
Type Location Additional Notes References point mutation 2L:1,387,323..1,387,324 comment=G to A nucleotide change at the second or third position of the Trp codon leads to a nonsense mutation (exact site of mutation unspecified) evidence=experimental pr_change=R902@|lea-PA reported_pr_change=R902@ (Rajagopalan et al., 2000)
Associated Sequence Data
DDBJ / EMBL / GenBank	DNA sequence Protein sequence Name
UniProtKB/Swiss-Prot
UniProtKB/TrEMBL
Progenitor genotype	leaEP2582 (Rajagopalan et al., 2000)
Nature of the lesion	Statement Reference Amino acid replacement: R845@ (revision of data in FBrf0132258). Amino acid replacements are relative to the 1406 amino acid residue predicted protein. (Dickson, 2001.3.14) Amino acid replacement: R902@. See Dickson, 2001.3.14, personal communication for subsequent revision of this information. (Rajagopalan et al., 2000)
Cytology
Phenotypic Data
Phenotypic Class
	lethal (with learobo2-4) (Spitzweck et al., 2010) neuroanatomy defective (Kinrade and Hidalgo, 2004, Parsons et al., 2003) neuroanatomy defective | embryonic stage (with learobo2-4) (Spitzweck et al., 2010)
Phenotype Manifest In
	cardioblast (Qian et al., 2005) dorsal branch primordium (Englund et al., 2002) fascicle (Kinrade and Hidalgo, 2004) ganglionic branch primordium (with learobo2-4) (Englund et al., 2002) germline cell | embryonic stage (with lea2) (Weyers et al., 2011) germline cell | embryonic stage (with learobo2-4) (Weyers et al., 2011) gonad | embryonic stage (with lea2) (Weyers et al., 2011) gonad | embryonic stage (with learobo2-4) (Weyers et al., 2011) gonadal sheath proper primordium | embryonic stage (with lea2) (Weyers et al., 2011) gonadal sheath proper primordium | embryonic stage (with learobo2-4) (Weyers et al., 2011) interface glial cell (Kinrade and Hidalgo, 2004) intermediate longitudinal fascicle (with learobo2-4) (Spitzweck et al., 2010) lateral longitudinal fascicle (with learobo2-4) (Spitzweck et al., 2010) lch5 neuron (Parsons et al., 2003) longitudinal connective (Rajagopalan et al., 2000, Rajagopalan et al., 2000) longitudinal connective (with learobo2-4) (Spitzweck et al., 2010)
Detailed Description
	Statement Reference lea[robo2-8]/lea[2] stage 13 embryos have gonads with unfused somatic gonadal precursor (SGP) clusters. By stage 15, SGP clusters fuse but gonads then fail to compact properly. Mutants also show germ cell ensheathment defects. lea[robo2-8]/lea[robo2-4] stage 13 embryos have gonads with unfused somatic gonadal precursor (SGP) clusters. By stage 15, SGP clusters fuse but gonads then fail to compact properly. Mutants also show germ cell ensheathment defects. (Weyers et al., 2011) Fas2-positive longitudinal axons show a number of defects in lea[robo2-4]/lea[robo2-8] stage 16 embryos; Fas2-positive axons extend across or along the midline in 23.7% of segments, intermediate Fas2-positive fascicles are fused or broken in 10.2% of hemisegments and lateral Fas2-positive fascicles are fused or broken in 29.9% of hemisegments. (Spitzweck et al., 2010) There are no significant defects in abdominal cluster dendritic branching in animals mutant for lea[robo2-8]. The dendrite morphology of class I and class IV neurons is normal in lea[robo2-8] single cell mutant clones. (Dimitrova et al., 2008) Subtle myocardial cell alignment defects are observed in learobo2-8 stage 16 embryos. (Qian et al., 2005) In embryonic stage 16 learobo2-8 mutants, axons defasciculate and longitudinal glia are disorganised, although the phenotype is rather weak (26% penetrance) and the glia do not migrate abnormally close to the midline. (Kinrade and Hidalgo, 2004) The lch5 axons are stalled, most frequently before turning point TP1 but sometimes between turning points TP1 and TP2, in 1% of hemisegments in mutant embryos. Stalling is also seen in dorsal cluster axons in about 1% of thoracic and abdominal hemisegments, but the most common defect in the dorsal cluster axons is projection in aberrant directions in 5-7% of hemisegments. (Parsons et al., 2003) 6% of ganglionic branches cross the midline in learobo2-4/learobo2-8 embryos and 15% of ganglionic branches fail to enter the central nervous system. 18% of dorsal tracheal branches are stalled or missing and 30% of the remaining branches fail to fuse over the heart. (Englund et al., 2002) Homozygous embryos show defects in the Fas2-expressing fascicles. 8.5% of embryos show fusion between the medial and intermediate fascicles, 23.0% show fusion between the lateral and intermediate fascicle, 4.7% show breaks in the intermediate fascicle and 15.2% show breaks in the lateral fascicle. (Rajagopalan et al., 2000) In robo8 homozygous mutants about a quarter of Fas2 positive axons in the ventral nerve cord are misrouted. These form bundles of varying thickness. (Rajagopalan et al., 2000)
External Data
Linkouts
Interactions
	Show the genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Enhanced by
Statement Reference lea[+]/learobo2-8, robo1 has neuroanatomy defective | recessive phenotype, enhanceable by captk01217/capt[+] (Wills et al., 2002)
Enhancer of
Statement Reference learobo2-8 is an enhancer of neuroanatomy defective phenotype of chb4, robo1 (Lee et al., 2004)
Other
Statement Reference lea[+]/learobo2-8, robo1 has neuroanatomy defective | recessive phenotype (Wills et al., 2002) lea[+]/learobo2-8, robo1 has neuroanatomy defective phenotype (Lee et al., 2004) learobo2-8, robo1 has neuroanatomy defective phenotype (Lee et al., 2004)
Phenotype Manifest In
Enhanced by
Statement Reference lea[+]/learobo2-8, robo1 has presumptive embryonic/larval central nervous system phenotype, enhanceable by captk01217/capt[+] (Wills et al., 2002) learobo2-8 has cardioblast phenotype, enhanceable by robo1 (Qian et al., 2005)
NOT Enhanced by
Statement Reference learobo2-4/learobo2-8 has germline cell | embryonic stage phenotype, non-enhanceable by robo31/robo31 (Weyers et al., 2011) learobo2-4/learobo2-8 has germline cell | embryonic stage phenotype, non-enhanceable by robo2/robo1 (Weyers et al., 2011) learobo2-4/learobo2-8 has gonad | embryonic stage phenotype, non-enhanceable by robo31/robo31 (Weyers et al., 2011) learobo2-4/learobo2-8 has gonad | embryonic stage phenotype, non-enhanceable by robo2/robo1 (Weyers et al., 2011) learobo2-4/learobo2-8 has gonadal sheath proper primordium | embryonic stage phenotype, non-enhanceable by robo31/robo31 (Weyers et al., 2011) learobo2-4/learobo2-8 has gonadal sheath proper primordium | embryonic stage phenotype, non-enhanceable by robo2/robo1 (Weyers et al., 2011)
Suppressed by
Statement Reference learobo2-4/learobo2-8 has ganglionic branch primordium phenotype, suppressible | partially by roboScer\UAS.T:Ivir\HA1,T:SS-wg/Scer\GAL4bs.Term (Englund et al., 2002)
Enhancer of
Statement Reference learobo2-8 is an enhancer of cardioblast phenotype of robo1 (Qian et al., 2005) learobo2-8 is an enhancer of embryonic/larval dorsal branch phenotype of stumpsems7 (Zhu et al., 2005) learobo2-8 is an enhancer of embryonic/larval neuron phenotype of chb4, robo1 (Lee et al., 2004)
NOT Enhancer of
Statement Reference learobo2-4/learobo2-8 is a non-enhancer of germline cell | embryonic stage phenotype of Df(2L)Exel7006/robo31 (Weyers et al., 2011) learobo2-4/learobo2-8 is a non-enhancer of germline cell | embryonic stage phenotype of robo2/robo1 (Weyers et al., 2011) learobo2-4/learobo2-8 is a non-enhancer of gonad | embryonic stage phenotype of Df(2L)Exel7006/robo31 (Weyers et al., 2011) learobo2-4/learobo2-8 is a non-enhancer of gonad | embryonic stage phenotype of robo2/robo1 (Weyers et al., 2011) learobo2-8 is a non-enhancer of dendrite phenotype of robo1 (Dimitrova et al., 2008) learobo2-8 is a non-enhancer of dorsal abdominal cluster phenotype of robo1 (Dimitrova et al., 2008)
NOT Suppressor of
Statement Reference lea[+]/learobo2-8 is a non-suppressor of dorsal branch | third instar larval stage phenotype of Scer\GAL4btl.PS, SdcdsRNA.Scer\UAS.cSa (Schulz et al., 2011)
Other
Statement Reference lea[+]/learobo2-8, robo1 has embryonic/larval neuron phenotype (Lee et al., 2004) lea[+]/learobo2-8, robo1 has presumptive embryonic/larval central nervous system phenotype (Wills et al., 2002) learobo2-8, robo1 has embryonic/larval neuron phenotype (Lee et al., 2004)
Additional Comments
Genetic Interactions
Statement Reference lea[robo2-8]/+ fails to suppress the dorsal branch fusion phenotype seen when Sdc[dsRNA.Scer\UAS.cSa] is expressed under the control of Scer\GAL4[btl.PS]. (Schulz et al., 2011) Many of the dorsal abdominal clusters in robo[1]/lea[robo2-8] mutant animals have branches that exceed the normal level of extension at approximately 21 and 22 hours after egg laying, but this phenotype is not significantly greater than the defects observed in robo[1] mutants. (Dimitrova et al., 2008) robo1, learobo2-8 double mutants show severe myocardial cell misalignment including gaps, intercalation, and double rows. (Qian et al., 2005) learobo2-8 enhances the defects in dorsal branch formation seen in stumpsems7 embryos; in the double mutant 71% are missing and 8% are stalled. (Zhu et al., 2005) Heterozygosity for learobo2-8 enhances the frequency of axons ectopically crossing the midline that is seen in robo1 chb4 double heterozygous embryos. robo1 learobo2-8 double heterozygous embryos have axons ectopically crossing the midline. (Lee et al., 2004) robo1 learobo2-8 double mutant embryos show misprojection of lch5 axons to the v'ch1 axon pathway in 11% of hemisegments (a similar frequency to robo1 single mutants). Stalling of the lch5 axons prior to turning point TP2, a characteristic of the learobo2-8 single mutant, is also seen in double mutant embryos, although at a higher frequency (6% of hemisegments). The dorsal cluster misprojection phenotype seen in learobo2-8 single mutant embryos is not seen in the robo1 learobo2-8 double mutant embryos; in the double mutant embryos the dorsal cluster axons follow a normal trajectory to the lateral region, although in 7% of hemisegments they grow abnormally from this point, either projecting along the v'ch1 route or growing intersegmentally. The lch5 cell bodies are located dorsal to their normal position in 11% of hemisegments and are aberrantly oriented in 3% of hemisegments of robo1 learobo2-8 double mutant embryos. Missing or aberrantly positioned spiracular branches and failure of motor axons to extend as far as the sensory neuron cluster are occasionally seen. (Parsons et al., 2003) Expression of roboScer\UAS.T:Ivir\HA1,T:wg under the control of Scer\GAL4bs.Term partially rescues the failure of ganglionic branches to enter the central nervous system that is seen in learobo2-4/learobo2-8 embryos and the weak midline crossing phenotype of the ganglionic branches seen in these embryos is also rescued. Expression of sliScer\UAS.cKa under the control of Scer\GAL4twi.PG in a learobo2-8 background does not result in any new tracheal branches growing from trunk metameres T2 to T9. (Englund et al., 2002) One copy of captk01217 enhances the frequency of midline crossing defects seen in robo1 learobo2-8 double mutant heterozygotes. (Wills et al., 2002)
Xenogenetic Interactions
Statement Reference
Complementation & Rescue Data
Comments
Stocks ( 0 )
Notes on Origin
Discoverer
External Crossreferences & Linkouts
Other Crossreferences
Linkouts
Synonyms & Secondary IDs ( 3 )
Reported As
Symbol Synonym	learobo2-8   robo28 (Kinrade and Hidalgo, 2004, Zhu et al., 2005, Lee et al., 2004, Johnson et al., 2004, Parsons et al., 2003, Wills et al., 2002, Englund et al., 2002, Dickson, 2001.3.14, Rajagopalan et al., 2000, Rajagopalan et al., 2000, Sano et al., 2005, Spitzweck et al., 2010, Dimitrova et al., 2008, Weyers et al., 2011, Schulz et al., 2011) roboD28 (Qian et al., 2005)
Name Synonym
Secondary FlyBase IDs
References ( 16 )
Research paper	Schulz et al., 2011, EMBO Rep. 12(10): 1039--1046 Drosophila syndecan regulates tracheal cell migration by stabilizing Robo levels. [FBrf0216287] Weyers et al., 2011, Dev. Biol. 353(2): 217--228 A genetic screen for mutations affecting gonad formation in Drosophila reveals a role for the slit/robo pathway. [FBrf0213539] Spitzweck et al., 2010, Cell 140(3): 409--420 Distinct Protein Domains and Expression Patterns Confer Divergent Axon Guidance Functions for Drosophila Robo Receptors. [FBrf0209892] Dimitrova et al., 2008, Dev. Biol. 324(1): 18--30 Slit and Robo regulate dendrite branching and elongation of space-filling neurons in Drosophila. [FBrf0207099] Qian et al., 2005, Curr. Biol. 15(24): 2271--2278 Slit and Robo control cardiac cell polarity and morphogenesis. [FBrf0190040] Sano et al., 2005, J. Cell Biol. 171(4): 675--683 Control of lateral migration and germ cell elimination by the Drosophila melanogaster lipid phosphate phosphatases Wunen and Wunen 2. [FBrf0190943] Zhu et al., 2005, Genetics 170(2): 767--777 A screen for genes that influence fibroblast growth factor signal transduction in Drosophila. [FBrf0187664] Johnson et al., 2004, Curr. Biol. 14(6): 499--504 Axonal heparan sulfate proteoglycans regulate the distribution and efficiency of the repellent slit during midline axon guidance. [FBrf0174485] Kinrade and Hidalgo, 2004, Neuron Glia Biol. 1: 101--112 Lateral neuron-glia interactions steer the response of axons to the Robo code. [FBrf0188594] Lee et al., 2004, Neuron 42(6): 913--926 The microtubule plus end tracking protein Orbit/MAST/CLASP acts downstream of the tyrosine kinase Abl in mediating axon guidance. [FBrf0179303] Parsons et al., 2003, Dev. Biol. 264(2): 363--375 roundabout gene family functions during sensory axon guidance in the Drosophila embryo are mediated by both Slit-dependent and Slit-independent mechanisms. [FBrf0167462] Englund et al., 2002, Development 129(21): 4941--4951 Attractive and repulsive functions of Slit are mediated by different receptors in the Drosophila trachea. [FBrf0151931] Wills et al., 2002, Neuron 36(4): 611--622 A Drosophila homolog of cyclase-associated proteins collaborates with the abl tyrosine kinase to control midline axon pathfinding. [FBrf0152273] Rajagopalan et al., 2000, Neuron 28(3): 767--777 Crossing the midline: roles and regulation of Robo receptors. [FBrf0132432] Rajagopalan et al., 2000, Cell 103(7): 1033--1045 Selecting a longitudinal pathway: robo receptors specify the lateral position of axons in the Drosophila CNS. [FBrf0132258]
Personal communication to FlyBase	Dickson, 2001.3.14, Molecular details of robo2 alleles. Molecular details of robo2 alleles. [FBrf0135264]