The bithorax complex of genes has three genes: Abdominal A, Abdominal B and Ultrabithorax. Here's very important existence of infra-abdominal (iab) regions; cis-acting regulatory sequences whose activities regulate the transcription of the Abdominal A and Abdominal B genes.
abdominal-A has effects that are apparent in the pattern of cuticle generated in the ectoderm and the pattern of muscle generated in mesoderm. With ectopic mesodermal abd-A expression, one finds alterations of the mature muscle patterns of the thoracic segments and the first abdominal segment. These include a change to a more abdominal-like identity for the thoracic longitudinal muscles. In some cases, a gain of one muscle is accompanied by the loss of another (Michelson A. M., 1994).
Bithorax complex role in segmentation
Upstream Genes |
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| hb | kr | kni | tll |
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en | AbdB | dpp |
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trx |
Abdominal-A |
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Antp | Scr |
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dpp | sca | csm | ||
Downstream Genes |
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Expression and regulation of the abd-A gene of Drosophila. Development 110: 1197-1207 (1990)
Cell-type-specific mechanisms of transcriptional repression by the homeotic gene products UBX and ABD-A in Drosophila embryos. EMBO J 12: 1099-1109 (1993)
A differential response element for the homeotics at the Antennapedia P1 promoter of Drosophila. Proc Natl Acad Sci U S A 91: 7420-7424 (1994)
Setting limits on homeotic gene function: restraint of Sex combs reduced activity by teashirt and other homeotic genes. EMBO J 13: 1132-1144 (1994)
Drosophila midgut morphogenesis requires the function of the segmentation gene odd-paired. Dev Biol 169: 580-595 (1995)
Homeotic genes of the Bithorax complex repress limb development in the abdomen of the Drosophila embryo through the target gene Distal-less. Cell 71: 437-450 (1992)
Regulation of a decapentaplegic midgut enhancer by homeotic proteins. Development 120: 3605-3619 (1994)
Homeotic control in Drosophila; the scabrous gene is an in vivo target of Ultrabithorax proteins. EMBO J 11: 3375-3384 (1992)
The Drosophila homeotic target gene centrosomin (cnn) encodes a novel centrosomal protein with leucine zippers and maps to a genomic region required for midgut morphogenesis. Development 121: 3861-3876 (1995)
Regulation of the infraabdominal regions of the bithorax complex of Drosophila by gap genes. Development 121: 1855-1866 (1995)
Regulation of the infraabdominal regions of the bithorax complex of Drosophila by gap genes. Development 121: 1855-1866 (1995)
Regulation of the infraabdominal regions of the bithorax complex of Drosophila by gap genes. Development 121: 1855-1866 (1995)
Regulation of the infraabdominal regions of the bithorax complex of Drosophila by gap genes. Development 121: 1855-1866 (1995)
Genetic factors controlling the expression of the abdominal-A gene of Drosophila within its domain. Mech Dev 46: 15-25 (1994)
Genetic factors controlling the expression of the abdominal-A gene of Drosophila within its domain. Mech Dev 46: 15-25 (1994)
Regulation of a decapentaplegic midgut enhancer by homeotic proteins. Development 120: 3605-3619 (1994)
Enhancer traps in the Drosophila bithorax complex mark parasegmental domains. Genetics 138: 387-399 (1994)
Trithorax regulates multiple homeotic genes in the bithorax and Antennapedia complexes and exerts different tissue-specific, parasegment-specific and promoter-specific effects on each. Development 117: 119-134 (1993)
Ectopic expression of UBX and ABD-B proteins during Drosophila embryogenesis: competition, not a functional hierarchy, explains phenotypic suppression. Development 116: 841-854 (1992)
Macias A., Casanova J. & Morata G. Expression and regulation of the abd-A gene of Drosophila. Development 110: 1197-1207 (1990)
Andrew, D. J., et. al. (1994). Setting limits on homeotic gene function: restraint of Sex combs reduced activity by teashirt and other homeotic genes. EMBO J 13: 1132-44
Appel, B. and Sakonju, S. (1993). Cell-type-specific mechanisms of transcriptional repression by the homeotic gene products UBX and abd-A in Drosophila embryos. EMBO J 12: 1099-109.
Breen, T. R. and Harte, P. J. (1993). Trithorax regulates multiple homeotic genes in the bithorax and Antennapedia complexes and exerts different tissue-specific, parasegment-specific and promoter-specific effects on each. Development 117: 119-34
Busturia, A. et al. (1989). Genetic structure of the abd-A gene of Drosophila. Development 107: 575-83
Casares, F. and Sanchez-Herrero, E. (1995). Regulation of the infraabdominal regions of the bithorax complex of Drosophila by gap genes. Development 121: 1855-1866
Casares, F., Calleja, M. and Sánchez-Herrero, E. (1996). functional similarity in appendage specification by the Ultrabithorax and abdominal-A Drosophila HOX genes. EMBO J. 15: 3934-42.
Castelli-Gair, J., et al. (1994). Dissecting the temporal requirements for homeotic gene function. Development 120: 1983-1995
Chiang, A., et al. (1995). Discrete Polycomb-binding sites in each parasegmental domain of the bithorax complex. Development 121: 1681-1689.
Cimbora, D. M. and Sakonju, S. (1995). Drosophila midgut morphogenesis requires the function of the segmentation gene odd-paired. Dev Biol 169: 580-595
Cumberledge, S., Szabad, J. and Sakonju, S. (1992). Gonad formation and development requires the abd-A domain of the bithorax complex in Drosophila melanogaster. Development 115: 395-402
Duboule, D. (1994). Guidebook to Homeobox Genes. Oxford U. Press, New York. pp. 78-80
Graba, Y., et al. (1992). Homeotic control in Drosophila; the scabrous gene is an in vivo target of Ultrabithorax proteins. EMBO J 11: 3375-84
Greig, S. and Akam, M. (1993). Homeotic genes autonomously specify one aspect of pattern in the Drosophila mesoderm. Nature 362: 630-2
Hendrickson, J. E. and Sakonju, S. (1995). Cis and trans interactions between the iab regulatory regions and abdominal-A and Abdominal-B in Drosophila melanogaster. Genetics 139: 835-848
Heuer, J. G., Li, K and Kaufman, T. C. (1995). The Drosophila homeotic target gene centrosomin (cnn) encodes a novel centrosomal protein with leucine zippers and maps to a genomic region required for midgut morphogenesis. Development 121: 3861-3876.
Jijakli, H. and Ghysen, A. (1992). Segmental determination in Drosophila central nervous system: analysis of the abdominal-A region of the bithorax complex. Int J Dev Biol 36: 93-9
Johnson, F. B., Parker, E. and Krasnow, M. A. (1995). Extradenticle protein is a selective cofactor for the Drosophila homeotics: role of the homeodomain and YPWM amino acid motif in the interaction. Proc Natl Acad Sci 92: 739-743
Karch, F., Bender W. and. Weiffenbach, B. (1990). abd-A expression in Drosophila embryos. Genes Dev 4: 1573-87
Lewis, E.B. (1978). A gene complex controlling segmentation in Drosophila. Nature 276: 565-70
Macias, A., Casanova, J. and Morata, G. (1990). Expression and regulation of the abd-A gene of Drosophila. Development 110: 1197-207
Macias, A., Pelaz, S. and Morata, G. (1994). Genetic factors controlling the expression of the abdominal-A gene of Drosophila within its domain. Mech. Dev. 46: 15-25.
McCall, K., O'Connor, M. B. and Bender, W. (1994). Enhancer traps in the Drosophila bithorax complex mark parasegmental domains. Genetics 138: 387-399
Manak, J. R. Mathies, L. D. and Scott, M. P. (1994). Regulation of a decapentaplegic midgut enhancer by homeotic proteins. Development 120: 3605-3619.
Mathies, L.D., Kerridge, S. and Scott, M.P. (1994). Role of the teashirt gene in Drosophila midgut morphogenesis: secreted proteins mediate the action of homeotic genes. Development 120: 2799-2809.
Michelson, A. M. (1994). Muscle pattern diversification in Drosophila is determined by the autonomous function of homeotic genes in the embryonic mesoderm. Development 120: 755-768
Pownall, M. E., et al. (1996). eFGF, Xcad3 and Hox genes form a molecular pathway that establishes the anteroposterior axis in Xenopus Development 122: 3881-3892
Prokop, A. and Technau, G. M. (1994). Early tagma-specific commitment of Drosophila CNS progenitor NB1-1. Development 120: 2567-78
Regulski, M. et. al. (1985). Homeo Box genes of the Antennapedia and Bithorax complexes of Drosophila. Cell 43: 71-80
Saffman, E. E. and Krasnow, M. A. (1994). A differential response element for the homeotics at the Antennapedia P1 promoter of Drosophila. Proc Natl Acad Sci 91: 7420-7424
Sanchez-Herrero, E. (1991). Control of the expression of the bithorax complex genes abdominal-A and Abdominal-B by cis-regulatory regions in Drosophila embryos. Development 111: 437-49
Sanchez-Herrero, E., et al. (1994). Developmental consequences of unrestricted expression of the abd-A gene of Drosophila. Mech Dev 46: 153-167
Vachon, G. (1992). Homeotic genes of the bithroax complex repress limb development in the abdomen of the Drosophila embryo through the target gene Distal-less. Cell 71: 437-450.
van Dijk, M. A. and Murre, C. (1994). Extradenticle raises the DNA binding
specificity of homeotic selector gene products. Cell 78: 617-624.
HOM-C
HOX-Pro