Allele Dmel\crb²

General Information
Symbol	Dmel\crb²	Species	D. melanogaster
Name		FlyBase ID	FBal0001817
Feature type	allele	Created / Updated	2006-08-22/2006-08-22
Associated gene	Dmel\crb

Allele class	amorph, loss of function
Mutagen	ethyl methanesulfonate
Nature of the Allele
Allele class	amorph (Tepass and Knust, 1993, Wodarz et al., 1993) loss of function (Pellikka et al., 2002)
Mutagen	ethyl methanesulfonate (Tearle and Nusslein-Volhard, 1987, Tepass and Knust, 1990, Wodarz et al., 1993)
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
Nature of the lesion	Statement Reference
Assay mode
Cytology	Polytene chromosomes normal. (Tepass and Knust, 1990)
Phenotypic Data
Phenotypic Class
	lethal \| embryonic stage \| recessive (Wodarz et al., 1993, Tepass et al., 1990, Tepass and Knust, 1990) cell polarity defective (Dunlop et al., 2004)
Phenotype Manifest In
	ectoderm (Dunlop et al., 2004) follicle cell \| somatic clone (Tanentzapf et al., 2000) retina \| cell autonomous \| conditional qualifier \| somatic clone (Johnson et al., 2002) rhabdomere \| cell autonomous \| somatic clone (Johnson et al., 2002) photoreceptor cell stalk \| cell autonomous \| somatic clone (Johnson et al., 2002) embryonic/first instar larval cuticle (Cox et al., 1996, Tanentzapf and Tepass, 2003) rhabdomere \| somatic clone (Izaddoost et al., 2002, Pellikka et al., 2002) adherens junction \| somatic clone (Izaddoost et al., 2002) photoreceptor cell stalk \| somatic clone (Izaddoost et al., 2002, Pellikka et al., 2002) larval salivary gland & embryo (Grawe et al., 1996) trachea (Grawe et al., 1996) embryonic epidermis (Grawe et al., 1996) amnioserosa (Grawe et al., 1996) zonula adherens (Grawe et al., 1996, Tepass, 1996, Tanentzapf and Tepass, 2003) spot adherens junction (Grawe et al., 1996) ommatidium \| somatic clone (Pellikka et al., 2002) interommatidial bristle \| somatic clone (Pellikka et al., 2002) zonula adherens & photoreceptor \| somatic clone (Pellikka et al., 2002) secondary pigment cell \| somatic clone (Pellikka et al., 2002) tertiary pigment cell \| somatic clone (Pellikka et al., 2002) adherens junction (Harris and Peifer, 2004) adherens junction & stage 9 embryo (Harris and Peifer, 2005) adherens junction & stage 10 embryo (Harris and Peifer, 2005)
Detailed Description
	Statement Reference Strong crb phenotype. Embryos almost completely lack cuticle due to cell death in epidermal primordium. P{lacZ}6-81 enhancer detection line specifically expresses Ecol\lacZ in the tracheal system, and reveals that morphogenetic abnormalities in the developing tracheal system result in a only a few aggregates of tracheal cells. Morphogenetic abnormalities and cell death were detected in the presumptive foregut and hindgut by fkh protein staining. Salivary glands also undergo cell death. (Tepass and Knust, 1990) Ectopic acridine orange and nile blue staining in epidermis. (Abrams et al., 1993) Epithelial cells of ectodermal origin lose their apicobasal polarity resulting in the loss of epithelial integrity and cell death. Both epidermal and amnioserosa cells of stage 10 lack zonula adherens junctions (ZA) and the number of spot adherens junctions (SAJ) is lower. The structure of all ectodermally derived epithelia is affected to varying extents. (Grawe et al., 1996) arm⁴; crb² double mutants exhibit a severe crb-like cuticle phenotype. (Cox et al., 1996) First defects in zonula adherens formation are seen at the onset of germband extension on the dorsal side of the embryo in the developing amnioserosa. The distribution of adherens junction material at the apicolateral boundary is more irregular. (Tepass, 1996) Homozygous follicle cell clones induced before formation of the follicular epithelium (FE) may lead to epithelial discontinuities or multilayering defects in posterior follicle cells. Small homozygous follicle clones, induced after the FE has formed, show no morphological defects. (Tanentzapf et al., 2000) In mutant clones in the eye the ommatidia show minor irregularities in arrangement and interommatidial bristle number and position. Rhabdomere shape, zonula adherens integrity and stalk membrane formation are all affected. Rhabdomeres extend only 40-60% of their normal length and are confined to the distal part of the retina. Secondary and tertiary pigment cells die, though not until well after eclosion. Rhabdomeres are larger than normal and may touch each other. At 50% of pupal development zonula adherens are fragmented though by 70% pd they have mostly recovered. Defects in photoreceptor cells are more pronounced proximally than distally. Photoreceptor cell stalk membrane is 50% shorter than wild type. Even in crb²/+ photoreceptors there is a 10% reduction in stalk membrane length. (Pellikka et al., 2002) Clones in the eye show lack of rhabdomere elongation. The rhabdomeres remain at the top of the retina and appear thicker than wild-type rhabdomeres. Adherens junctions stretch further basolaterally than in wild type. Those at the distal portion of the retina are variable in size and those that are proximal are discontinuous and thin. The adherens junctions attaching the photoreceptors to the floor of the retina remain relatively intact. (Izaddoost et al., 2002) When flies with eyes containing homozygous clones are kept in constant light conditions for 7 days, the retina shows massive degeneration. This phenotype is not seen under low light conditions, instead their rhabdomeres are thicker and shorter compared to wild-type and are often found in close contact with other rhabdomeres of the same ommatidium. The rhabdomeres fail to reach the basal lamina and extend from the distal pole near the lens to only about one third of the normal length. In addition, the stalk membrane is reduced in length, however the tightly stacked internal structure of the rhabdomere is unaffected. When grown in vitamin A-deficient conditions in continuous light, mutant photoreceptors cells show smaller. thinner rhabdomeres, other morphogenetic defects similar to mutant animals raised on standard medium in the dark. However only minor signs to photoreceptor degeneration is seen. (Johnson et al., 2002) Most cuticle is absent in mutant embryos and the remaining cuticle forms many small granules. The zonula adherens never assembles from spot adherens junctions. (Tanentzapf and Tepass, 2003) Homozygous embryos show a disruption in ectodermal cell polarity from stage 8. Stage 13 homozygous embryos have a relatively normal central nervous system. (Dunlop et al., 2004) crb²/+ embryos show normal cardiac cell alignment. (Qian et al., 2005) Adherens junctions are fragmented in stage 9 crb[2] zygotic mutant embryos. (Harris and Peifer, 2004) The adherens junctions in stage 9 and 10 crb[2] zygotic mutants fragment and become randomly positioned around the cell cortex and along the basolateral membrane as epidermal cells dissociate. The gut epithelium of crb[2] mutants maintains basic epithelial structure at stage 10. (Harris and Peifer, 2005)
Interactions
	Show the genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Enhancer of
Statement Reference crb²/crb[+] is an enhancer of lethal phenotype of kst¹/kst² (Medina et al., 2002) crb² is an enhancer of visible phenotype of Ret^MEN2B.GMR (Read et al., 2005) crb²/crb[+] is an enhancer of lethal phenotype of kst^B1-14.1/kst¹ (Medina et al., 2002) crb²/crb[+] is an enhancer of lethal phenotype of kst^B1-14.1/kst² (Medina et al., 2002) crb²/crb[+] is an enhancer of visible phenotype of CycE^JP (Brumby et al., 2004)
NOT Enhancer of
Statement Reference crb² is a non-enhancer of visible phenotype of Ret^MEN2A.GMR (Read et al., 2005)
NOT Suppressor of
Statement Reference crb² is a non-suppressor of visible phenotype of Ret^MEN2A.GMR (Read et al., 2005)
Other
Statement Reference crb²/crb[+], gkt^G85 has cell polarity defective phenotype (Dunlop et al., 2004) crb², gkt^G85 has cell polarity defective phenotype (Dunlop et al., 2004)
Phenotype Manifest In
Suppressed by
Statement Reference crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially \| germ-line clone by scrib⁶⁷³/scrib⁶⁷³ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by dlg1[+]/dlg1¹⁴ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by dlg1¹⁴/dlg1¹⁴ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by l(2)gl[+]/l(2)gl²⁷⁵ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by l(2)gl²⁷⁵/l(2)gl²⁷⁵ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by l(2)gl⁴/l(2)gl⁴ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by scrib[+]/scrib⁶⁷³ (Tanentzapf and Tepass, 2003) crb² has zonula adherens phenotype, suppressible \| partially by l(2)gl⁴ (Tanentzapf and Tepass, 2003) crb² has zonula adherens phenotype, suppressible \| partially by scrib⁶⁷³ (Tanentzapf and Tepass, 2003) crb² has embryonic/first instar larval cuticle phenotype, suppressible \| partially by l(2)gl[+]/l(2)gl⁴ (Tanentzapf and Tepass, 2003) crb² has retina \| somatic clone \| conditional qualifier \| cell autonomous phenotype, suppressible by BacA\p35^GMR.PH (Johnson et al., 2002)
NOT suppressed by
Statement Reference crb² has rhabdomere \| somatic clone \| cell autonomous phenotype, non-suppressible by BacA\p35^GMR.PH (Johnson et al., 2002) crb² has photoreceptor cell stalk \| somatic clone \| cell autonomous phenotype, non-suppressible by BacA\p35^GMR.PH (Johnson et al., 2002)
Enhancer of
Statement Reference crb²/crb[+] is an enhancer of photoreceptor cell stalk phenotype of kst¹/kst² (Pellikka et al., 2002) crb²/crb[+] is an enhancer of rhabdomere \| somatic clone phenotype of kst¹/kst² (Pellikka et al., 2002) crb² is an enhancer of eye phenotype of Ret^MEN2B.GMR (Read et al., 2005) crb²/crb[+] is an enhancer of eye phenotype of CycE^JP (Brumby et al., 2004)
NOT Enhancer of
Statement Reference crb² is a non-enhancer of eye phenotype of Ret^MEN2A.GMR (Read et al., 2005)
NOT Suppressor of
Statement Reference crb² is a non-suppressor of eye phenotype of Ret^MEN2A.GMR (Read et al., 2005)
Other
Statement Reference crb²/crb[+], kst¹/kst² has photoreceptor cell stalk phenotype (Pellikka et al., 2002) crb²/crb[+], kst¹/kst² has rhabdomere \| somatic clone phenotype (Pellikka et al., 2002) crb², kst¹/kst² has photoreceptor cell stalk phenotype (Pellikka et al., 2002) crb², kst¹/kst² has rhabdomere \| somatic clone phenotype (Pellikka et al., 2002)
Additional Comments
Genetic Interactions
Statement Reference crb²/crb⁺, kst¹/kst² mutants have normal zonula adherens but photoreceptor stalk membranes are much shorter than in wild type, kst homozygous or crb heterozygous photoreceptor cells. (Pellikka et al., 2002) The addition of BacA\p35^GMR.PH to crb² animals suppresses the light sensitive degeneration phenotype seen in mutant clones in the eye, though the phenotypes associated with low light conditions remain. (Johnson et al., 2002) l(2)gl⁴ shows marked rescue of the crb² phenotype, as the majority of the cuticle is restored in the double mutant embryos. Embryos lacking both crb and scrib maternal and zygotic function (derived from scrib⁶⁷³ crb² homozygous germline clones) have a phenotype similar to that of embryos derived from scrib⁶⁷³ homozygous germline clones (lacking scrib maternal and zygotic function). Formation of the zonula adherens is largely rescued in crb² ; l(2)gl⁴ or crb² scrib⁶⁷³ double mutant embryos. crb² ; Df(3L)H99 double mutant embryos have crb-mutant like cuticle defects, but the number of cuticle vesicles produced is greatly increased compared to crb² single mutants. These cuticle vesicles have a normal junctional complex containing a zonula adherens and a septate junction. (Tanentzapf and Tepass, 2003) gkt^G85/gkt^G85 ; crb²/+ embryos show a severe disruption in epithelial polarity at stage 11. (Dunlop et al., 2004) 96% of sli²/+, crb²/+ embryos show normal cardiac cell alignment. (Qian et al., 2005)
Xenogenetic Interactions
Statement Reference
Complementation & Rescue Data
Fails to complement	crb^j1B5 (Moussian, 2000.12.7) crb^S025807b (Harden et al., 2002) crb^S010409 (Harden et al., 2002) crb^S050920 (Harden et al., 2002) crb^S025819 (Harden et al., 2002) crb^S025817 (Harden et al., 2002)
Rescued by	crb² is rescued by crb^+t33 (Tepass et al., 1990) crb² is rescued by Scer\GAL4^unspecified/crb^{intra.Scer\UAS.T:Hsap\MYC} (Wodarz et al., 1995)
Partially rescued by	crb² is partially rescued by crb^intra.GMR (Johnson et al., 2002)
Comments
Stocks ( 2 )
Bloomington	3448 ru¹ h¹ th¹ st¹ cu¹ sr¹ e^s crb² ca¹/TM3, Sb¹ Ser¹
Kyoto	107045 ru¹ h¹ th¹ st¹ cu¹ sr¹ e^s crb² ca¹/TM3, Sb¹ Ser¹
Notes on Origin
Discoverer

Comments
	Strong crb allele. (Tepass and Knust, 1990) The phenotype of amorphic crb mutants is essentially the same as the phenotype of amorphic sdt mutants. Embryos doubly mutant for sdt and crb mutants show the same phenotype as embryos singly mutant for either gene. Double mutants for Egfr and sdt or crb show an enhancement of the sdt or crb mutant phenotype. Phenotype can be alleviated by a duplication for sdt⁺, Dp(1;2)sn⁺72d. (Tepass and Knust, 1993)
Synonyms & Secondary IDs ( 4 )
Reported As
Symbol Synonym	crb² (Harris and Peifer, 2004, Harris and Peifer, 2005) crb^11A22 (Qian et al., 2005, Dunlop et al., 2004, Harden et al., 2002, Nam and Choi, 2003, Tanentzapf and Tepass, 2003, Johnson et al., 2002, Izaddoost et al., 2002, Pellikka et al., 2002, Fusse and Hoch, 2002, Hong et al., 2001, Lu et al., 2001, Tanentzapf et al., 2000, Brodsky et al., 2000, Klebes and Knust, 2000, Yu et al., 1999, Nordstrom et al., 1996, Tepass, 1996, Cox et al., 1996, Grawe et al., 1996, Knust et al., 1993, Wodarz et al., 1993, Abrams et al., 1993, Tepass and Knust, 1993, Tepass and Knust, 1990, Tepass et al., 1990, Bachmann et al., 2001) crb^11A (Jack and Myette, 1999, Pereira et al., 1995, Wodarz et al., 1995, Tearle and Nusslein-Volhard, 1987, ) crumbs^11A22 (Medina et al., 2002)
Name Synonym
Secondary FlyBase IDs

References ( 36 )

Generate a list of	All references relating to this allele ( 36 )

List References by type	Research paper ( 33 ) Review ( 1 ) Personal communication to FlyBase ( 1 ) Stock list ( 1 )
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Allele Dmel\crb2

Allele Dmel\crb²