Asunto(s)

Síndrome de Bardet-Biedl/genética , Herencia Multifactorial , Poliposis Adenomatosa del Colon/genética , Alelos , Animales , Genes APC , Genes Dominantes , Genes Recesivos , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Proteínas Asociadas a Microtúbulos , Atrofia Muscular Espinal/genética , Mutación , Fenotipo , Proteínas/genética

RESUMEN

Our primary objective was to identify techniques to transform the genome of the honey bee (Apis mellifera) with foreign DNA constructs. The strategy we adopted was to linearize foreign DNA and introduce it with sperm during the instrumental insemination of virgin queen honey bees. We analysed extracts from larvae within the same cohort and isolated the predicted fragment by means of PCR amplification of genomic DNA. Larvae that carried the construct also expressed the introduced DNA. We propagated several transgenic lines for up to three generations, which demonstrates its heritability. Once carried by a queen, the construct can be detected in that queen's larvae over several months. However, there was no evidence of integration of the construct, at least as determined by genomic Southern analysis. Nevertheless, this demonstrates the general viability of the technique for introduction of DNA, and it should be augmented by further use of transposable elements that enhance integration.

Asunto(s)

Abejas/genética , Espermatozoides/fisiología , Transformación Genética , Animales , Animales Modificados Genéticamente , Southern Blotting , Femenino , Proteínas Fluorescentes Verdes , Proteínas Luminiscentes/genética , Masculino , Plásmidos , Reacción en Cadena de la Polimerasa

RESUMEN

Developmental regulators and cell cycle regulators have to interface in order to ensure appropriate cell proliferation during organogenesis. Our analysis of the roles of the pan-neural genes deadpan and asense defines critical roles for these genes in regulation of mitotic activities in the larval optic lobes. Loss of deadpan results in reduced cell proliferation, while ectopic deadpan expression causes over-proliferation. In contrast, loss of asense results in increased proliferation, while ectopic asense expression causes reduced proliferation. Consistent with these observations endogenous Deadpan is expressed in mitotic areas of the optic lobes, and endogenous Asense is expressed in cells that will become quiescent. Altered Deadpan or Asense expression results in altered expression of the cyclin dependent kinase inhibitor gene dacapo. Thus, regulation of mitotic activity during optic lobe development may, at least in part, involve deadpan and asense mediated regulation of the cyclin dependent kinase inhibitor gene dacapo. genesis 26:77-85, 2000.

Asunto(s)

Quinasas Ciclina-Dependientes/fisiología , Proteínas de Unión al ADN/fisiología , Proteínas de Drosophila , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Secuencias Hélice-Asa-Hélice/fisiología , Proteínas de Insectos/fisiología , Mitosis/genética , Proteínas del Tejido Nervioso/fisiología , Proteínas Nucleares/biosíntesis , Proteínas Nucleares/fisiología , Lóbulo Óptico de Animales no Mamíferos/crecimiento & desarrollo , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , División Celular/genética , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Hibridación in Situ , Proteínas de Insectos/biosíntesis , Proteínas de Insectos/genética , Larva , Proteínas del Tejido Nervioso/biosíntesis , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , Lóbulo Óptico de Animales no Mamíferos/metabolismo , Fenotipo

RESUMEN

Organogenesis requires coordination between developmental specific regulators and genes governing cell proliferation. Here we show that Drosophila prospero encodes a critical regulator of the transition from mitotically active cells to terminal differentiated neurons. Loss of pros results in aberrant expression of multiple cell-cycle regulatory genes and ectopic mitotic activity. In contrast, ectopic pros expression causes transcriptional suppression of multiple cell-cycle regulatory genes and premature termination of cell division. pros activity, hence, provides a critical regulatory link between neuronal lineage development and transcriptional regulation of cell cycle regulatory genes.

Asunto(s)

Proteínas de Drosophila , Drosophila melanogaster/fisiología , Proteínas del Tejido Nervioso/fisiología , Neuronas/fisiología , Proteínas Nucleares/fisiología , Factores de Transcripción , Animales , Ciclo Celular/genética , Diferenciación Celular/fisiología , División Celular/fisiología , Regulación del Desarrollo de la Expresión Génica/fisiología , Genes Reguladores/genética , Genes Reguladores/fisiología , Genes cdc/fisiología , Proteínas de Homeodominio/biosíntesis , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/fisiología , Mutación , Proteínas del Tejido Nervioso/biosíntesis , Proteínas del Tejido Nervioso/deficiencia , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/biosíntesis , Proteínas Nucleares/deficiencia , Proteínas Nucleares/genética , Transcripción Genética/genética , Transcripción Genética/fisiología

RESUMEN

The panneural protein Prospero is required for proper differentiation of neuronal lineages and proper expression of several genes in the nervous system of Drosophila. Prospero is an evolutionarily conserved, homeodomain-related protein with dual subcellular localization. Here we show that Prospero is a sequence-specific DNA-binding protein with novel sequence preferences that can act as a transcription factor. In this role, Prospero can interact with homeodomain proteins to differentially modulate their DNA-binding properties. The relevance of functional interactions between Prospero and homeodomain proteins is supported by the observation that Prospero, together with the homeodomain protein Deformed, is required for proper regulation of a Deformed-dependent neural-specific transcriptional enhancer. We have localized the DNA-binding and homeodomain protein-interacting activities of Prospero to its highly conserved C-terminal region, and we have shown that the two regulatory capacities are independent.

Asunto(s)

Proteínas de Drosophila , Proteínas de Homeodominio/genética , Proteínas del Tejido Nervioso/metabolismo , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , Sitios de Unión , Células COS , Secuencia de Consenso , ADN , Elementos de Facilitación Genéticos , Regulación de la Expresión Génica , Proteínas de Homeodominio/metabolismo , Neuronas/metabolismo , Transcripción Genética

RESUMEN

The Drosophila EXD protein and its mammalian counterparts, the PBX proteins, have been proposed to function in HOX target selectivity. Here we show that exd function is required for the autoactivation phase of Dfd expression in the posterior head. Mutations that change the affinity of a small autoactivation element for EXD protein result in corresponding changes in the element's embryonic activity. Our data suggest that the EXD and DFD proteins directly activate this element in maxillary cells without cooperatively binding to a specialized heterodimer binding site. Based on the types of homeotic transformations and changes in gene expression observed in exd mutant embryos, we propose a new model for EXD/PBX action in which these proteins are required for HOX protein transcriptional activation functions, but dispensable for HOX transcriptional repression functions. Although the selection of a specific target gene by a HOX protein versus another may be explained in some cases by the selective modulation of HOX binding specificity by EXD, we favor the idea that EXD interacts in a more general sense with most HOX proteins to switch them into a state where they are capable of transcriptional activation.

Asunto(s)

Proteínas de Unión al ADN/metabolismo , Proteínas de Drosophila , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas de Homeodominio/genética , Proteínas Represoras/metabolismo , Transactivadores/metabolismo , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , ADN/metabolismo , Huella de ADN , Proteínas de Unión al ADN/genética , Drosophila/embriología , Drosophila/genética , Modelos Genéticos , Datos de Secuencia Molecular , Mutación , Proteínas Represoras/genética , Transactivadores/genética , Factores de Transcripción/genética

RESUMEN

The function of the neuronal differentiation gene daughterless (da) is required for the proper initiation of neuronal lineage development in all PNS lineages following the selection of neuronal precursor cells. Previous studies have shown that the ubiquitously expressed da protein is required for the proper expression of neuronal precursor genes and lineage identity genes in the PNS of Drosophila melanogaster embryos. These genes are required for differentiation and cell fate determination in the developing PNS. These findings, however, did not explain the failure of the nascent PNS precursors to undergo a normal cell cycle and divide. Here we show that four genes whose products are required for various stages of the cell cycle are misexpressed in the PNS of da mutant embryos. This suggests that all aspects of PNS precursor differentiation examined so far are under the transcriptional control of da.

Asunto(s)

Proteínas de Ciclo Celular/genética , Proteínas de Unión al ADN/fisiología , Proteínas de Drosophila , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica/genética , Proteínas Nucleares/fisiología , Factores de Transcripción/fisiología , Animales , Apoptosis/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Ciclo Celular/genética , Proteínas de Unión al ADN/genética , Drosophila melanogaster/embriología , Embrión no Mamífero/química , Genes de Insecto/fisiología , Mutación , Proteínas Nucleares/genética , Sistema Nervioso Periférico/embriología , ARN Mensajero/análisis , Factores de Transcripción/genética , Transcripción Genética

RESUMEN

Most cell types in multicellular eukaryotes exit from the mitotic cell cycle before terminal differentiation. We show that the dacapo gene is required to arrest the epidermal cell proliferation at the correct developmental stage during Drosophila embryogenesis. dacapo encodes an inhibitor of cyclin E/cdk2 complexes with similarity to the vertebrate Cip/Kip inhibitors. dacapo is transiently expressed beginning late in the G2 phase preceding the terminal division (mitosis 16). Mutants unable to express the inhibitor fail to arrest cell proliferation after mitosis 16 and progress through an extra division cycle. Conversely, premature dacapo expression in transgenic embryos results in a precocious G1 arrest.

Asunto(s)

Quinasas CDC2-CDC28 , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Ciclinas/antagonistas & inhibidores , Proteínas de Drosophila , Drosophila melanogaster/embriología , Inhibidores de Crecimiento/genética , Proteínas de Insectos/fisiología , Proteínas Nucleares/fisiología , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Secuencia de Aminoácidos , Animales , Secuencia de Bases , División Celular , Quinasa 2 Dependiente de la Ciclina , ADN Complementario/genética , Drosophila melanogaster/citología , Drosophila melanogaster/enzimología , Inhibidores Enzimáticos , Células Epidérmicas , Regulación del Desarrollo de la Expresión Génica , Genes de Insecto , Sustancias Macromoleculares , Datos de Secuencia Molecular , Unión Proteica , ARN Mensajero/genética , Alineación de Secuencia

RESUMEN

During neurogenesis in Drosophila, ectodermal cells are endowed with the capacity to become neuronal precursors. Following their selection, these cells initiate neuronal lineage development and differentiation. The processes of neuronal precursor specification and neuronal lineage development require the activities of several groups of genes functioning in a complex, hierarchical regulatory network. Whereas the proneural genes promote neurogenic potential, neurogenic genes restrict the acquisition of this identity to a subset of ectodermal cells. Following their selection, these cells express the pan neural neuronal precursor genes and a set of neuronal lineage identity genes. While lineage identity genes allow the various lineages to acquire specific identities, neuronal precursor genes presumably regulate functional and developmental characteristics common to all neuronal precursor cells.

Asunto(s)

Drosophila/embriología , Drosophila/genética , Ectodermo/fisiología , Regulación de la Expresión Génica , Genes de Insecto , Sistema Nervioso/embriología , Animales , Diferenciación Celular , Embrión no Mamífero/fisiología , Proteínas del Tejido Nervioso/biosíntesis , Neuronas/citología , Neuronas/fisiología , Transcripción Genética

RESUMEN

We have isolated the Drosophila disc proliferation abnormal (dpa) gene, a member of the MCM family of DNA replication factors. Members of this family of proteins are required for DNA replication in yeast. A dpa null mutant dies during pupal stages because imaginal tissues necessary for the formation of the adult fly fail to proliferate normally. Beginning in late embryogenesis BrdU labeling reveals DNA replication defects in mitotically proliferating cells. In contrast, dpa is dispensable for endoreplication, a specialized cell cycle consisting of consecutive rounds of S phases without intervening mitosis. Our studies suggest an essential role for dpa in mitotic DNA replication but not in endoreplication. Thus, dpa is not a general replication factor but may play a specialized regulatory role in DNA replication.

Asunto(s)

Proteínas de Ciclo Celular/genética , Replicación del ADN/genética , Proteínas de Unión al ADN , Proteínas de Drosophila , Drosophila/genética , Proteínas Fúngicas/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Proteínas de Ciclo Celular/metabolismo , Clonación Molecular , Drosophila/embriología , Mitosis/genética , Datos de Secuencia Molecular , Mutación , Alineación de Secuencia

RESUMEN

The Drosophila scratch (scrt) gene is expressed in most or all neuronal precursor cells and encodes a predicted zinc finger transcription factor closely related to the product of the mesoderm determination gene snail (sna). Adult flies homozygous for scrt null alleles have a reduced number of photoreceptors in the eye, and embryos lacking the function of both scrt and the pan-neural gene deadpan (dpn), which encodes a basic helix-loop-helix (bHLH) protein, exhibit a significant loss of neurons. Conversely, ectopic expression of a scrt transgene during embryonic and adult development leads to the production of supernumerary neurons. Consistent with scrt functioning as a transcription factor, various genes are more broadly expressed than normal in scrt null mutants. Reciprocally, these same genes are expressed at reduced levels in response to ectopic scrt expression. We propose that scrt promotes neuronal cell fates by suppressing expression of genes promoting non-neuronal cell fates. We discuss the similarities between the roles of the ancestrally related scrt, sna, and escargot (esc) genes in regulating cell fate choices.

Asunto(s)

Proteínas de Unión al ADN/genética , Proteínas de Drosophila , Drosophila/genética , Neuronas/citología , Factores de Transcripción/genética , Dedos de Zinc/genética , Secuencia de Aminoácidos , Animales , Diferenciación Celular/genética , Mapeo Cromosómico , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/fisiología , Drosophila/embriología , Regulación del Desarrollo de la Expresión Génica/genética , Hibridación in Situ , Mesodermo/citología , Mesodermo/metabolismo , Datos de Secuencia Molecular , Mutación , Neuronas/metabolismo , Fenotipo , Células Fotorreceptoras de Invertebrados/citología , Análisis de Secuencia , Homología de Secuencia de Aminoácido , Factores de Transcripción de la Familia Snail , Factores de Transcripción/química , Factores de Transcripción/fisiología , Transcripción Genética/genética

Asunto(s)

Sistema Nervioso Central/enzimología , Óxido Nítrico Sintasa/biosíntesis , Óxido Nítrico Sintasa/genética , Regiones Promotoras Genéticas/genética , Transcripción Genética/fisiología , Secuencia de Bases , Regulación Enzimológica de la Expresión Génica/fisiología , Humanos , Datos de Secuencia Molecular

RESUMEN

The first steps of neuronal precursor formation require several genes that encode transcription regulators with the helix-loop-helix (HLH) motif, including the proneural genes of the achaete-scute complex AS-C (achaete (ac), scute (sc) and lethal of scute (l'sc)) and daughterless (da). The da protein dimerizes with AS-C products in vitro to form DNA-binding proteins. Previous studies have shown that the AS-C genes are expressed initially in discrete clusters of ectodermal cells (the proneural clusters) and then more strongly in the neuronal precursors that arise from these clusters and delaminate from the epidermal layer. In this paper, we studied the distribution of da protein with an antibody raised against Da. We found that Da is ubiquitously but non-uniformly distributed. Within the ectodermal layer, its level is neither elevated (as in the case of AS-C genes) nor reduced (as in the case of emc product) in the proneural cluster. It is, however, at higher levels in many neuronal precursors. We further studied the requirement of da in neuronal precursor development by using a variety of markers for neuronal precursors. Our results reveal the existence of at least two stages in neuronal precursor formation. da is not required for the initial appearance of nascent neuronal precursors but is required for these cells to express multiple neuronal precursor genes and to produce the normal number of neurons.

Asunto(s)

Proteínas de Unión al ADN/genética , Proteínas de Drosophila , Drosophila/embriología , Drosophila/genética , Genes de Insecto , Neuronas/fisiología , Proteínas Nucleares/genética , Células Madre/fisiología , Factores de Transcripción/genética , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Inmunohistoquímica , Hibridación in Situ , Datos de Secuencia Molecular , Neuronas/citología , Células Madre/citología

RESUMEN

Neural precursor cells in Drosophila acquire their identity early during their formation. In an attempt to determine whether all neural precursors share a set of genetic machinery, perhaps to control properties of differentiation common to all neurons, we used the enhancer-trap method to identify several genes (pan-neural genes) that are expressed in all neurons and/or their precursors. One of the pan-neural genes is deadpan, which encodes a helix-loop-helix protein closely related to the product of the segmentation gene hairy. The function of deadpan is essential for viability and is likely to be involved in the functional rather than the morphological differentiation of neurons.

Asunto(s)

Proteínas de Unión al ADN/genética , Proteínas de Drosophila , Drosophila/genética , Genes de Insecto , Proteínas Nucleares/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Mapeo Cromosómico , Drosophila/embriología , Drosophila/fisiología , Embrión no Mamífero/fisiología , Datos de Secuencia Molecular , Neuronas/fisiología , Estructura Secundaria de Proteína , Mapeo Restrictivo , Homología de Secuencia de Aminoácido , Transcripción Genética

RESUMEN

In Drosophila, sex is determined by the X:A ratio. One major numerator element on the X chromosome is sisterless-b (sis-b), also called scute, which encodes an HLH-type transcription factor. We report here that an essential pan-neural gene, the autosomal HLH gene deadpan (dpn), acts as a denominator element. As revealed by dosage-dependent dominant interactions, males die with too high a ratio of sc+ to dpn+, caused by misexpression of Sex lethal (Sxl) in embryos, and females die with too low a ratio of sc+ to dpn+, because of altered embryonic Sxl expression. In addition, we found that the HLH gene extramacrochaetae (emc), like daughterless (da), is needed maternally for proper communication of the X:A ratio, thus supporting the idea that a set of HLH genes comprises a functional cassette that makes a sensitive and stable genetic switch used in both neural determination and sex determination.

Asunto(s)

Drosophila/genética , Diferenciación Sexual/genética , Animales , Deleción Cromosómica , Compensación de Dosificación (Genética) , Drosophila/embriología , Femenino , Genes Letales , Masculino , Familia de Multigenes , Sistema Nervioso/embriología , Supresión Genética

RESUMEN

Through enhancer detection screens we have isolated 14 insertions in an essential gene that is expressed in embryonic sensory mother cells (SMC), in most cells of the mature embryonic peripheral nervous system (PNS), and in glial cells of the PNS and the central nervous system (CNS). Embryos homozygote for amorphic alleles die, but show no obvious defects in their cuticle, PNS or CNS. The gene has been named couch potato (cpo) because several insertional alleles alter adult behavior. Homozygous hypomorphic cpo flies recover slowly from ether anaesthesia, show aberrant flight behavior, fail to move toward light and do not exhibit normal negative behavior. However, the flies are able to groom and walk, and some are able to fly when prodded, indicating that not all processes required for behavior are severely affected. A molecular analysis shows that the 14 insertions are confined to a few hundred nucleotides which probably contain key regulatory sequences of the gene. The orientation of these insertions and their position within this DNA fragment play an important role in the couch potato phenotype. In situ hybridization to whole mount embryos suggest that some insertions affect the levels of transcription of cpo in most cells in which it is expressed.

Asunto(s)

Conducta Animal , Drosophila melanogaster/genética , Genes , Proteínas del Tejido Nervioso/genética , Alelos , Animales , Drosophila melanogaster/embriología , Drosophila melanogaster/fisiología , Embrión no Mamífero/metabolismo , Embrión no Mamífero/ultraestructura , Genes Letales , Genética Conductual , Morfogénesis , Mutación , Proteínas del Tejido Nervioso/fisiología , Neuroglía/química , Nervios Periféricos/química , Nervios Periféricos/embriología , Proteínas Recombinantes de Fusión/biosíntesis , Células Madre/fisiología

RESUMEN

Neurogenesis in Drosophila begins with the formation of neuronal precursors, which give rise to neurons of individual identity. To find out whether there are genes that are expressed in most or all neuronal precursors and are involved in controlling particular aspects of neuronal differentiation, we used the enhancer-trap method to screen for such "neuronal precursor genes." One gene of this group is prospero. Our mutant analysis indicates that prospero regulates other neuronal precursor genes and is essential for the axonal outgrowth and pathfinding of numerous central and peripheral neurons. prospero encodes a large nuclear protein with multiple homopolymeric amino acid stretches and is expressed in neuronal precursors early during their formation. It is probably generally required for proper neuronal differentiation.

Asunto(s)

Axones/fisiología , Drosophila melanogaster/genética , Genes , Proteínas Nucleares/genética , Precursores de Proteínas/genética , Transcripción Genética , Secuencia de Aminoácidos , Animales , Anticuerpos , Secuencia de Bases , Clonación Molecular , Drosophila melanogaster/embriología , Drosophila melanogaster/fisiología , Embrión no Mamífero/fisiología , Datos de Secuencia Molecular , Mutagénesis Insercional , Péptidos/síntesis química , Péptidos/inmunología , Reacción en Cadena de la Polimerasa , ARN/genética , Mapeo Restrictivo

RESUMEN

By studying neuroectoderm formation in the absence of mesoderm and mesectoderm in mutants of the zygotic genes snail and twist, we have found that the number of neuroblasts is not reduced in these mutants, suggesting that mesoderm and mesectoderm are not essential for the initiation of neural development. The position of the neuroectoderm, however, is ventrally shifted: Neuroectoderm takes over the presumptive peripheral mesoderm domain in single mutants, whereas the entire presumptive mesoderm domain in double mutants takes on the neuroectodermal fate. The shifted neuroectoderm still requires the proneural genes and the neurogenic genes. This shift is unlikely to be due to any shift in the nuclear localization gradient of the maternally supplied dorsal protein. A model for cell fate determination of the neuroectoderm, mesectoderm, and mesoderm will be discussed.

Asunto(s)

Sistema Nervioso Central/embriología , Proteínas de Drosophila , Ectodermo/fisiología , Mesodermo/fisiología , Fosfoproteínas , Factores de Transcripción , Animales , Drosophila/embriología , Drosophila/genética , Inmunohistoquímica , Mutación , Neuronas/citología , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fenotipo , Tráquea/crecimiento & desarrollo , Proteína 1 Relacionada con Twist , Dedos de Zinc/genética

Asunto(s)

Proteínas de Unión al ADN/fisiología , Sistema Nervioso/crecimiento & desarrollo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Proteínas de Unión al ADN/genética , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Datos de Secuencia Molecular , Factores de Transcripción/genética , Factores de Transcripción/fisiología

RESUMEN

A P-element vector has been constructed and used to generate lines of flies with single autosomal P-element insertions. The lines were analyzed in two ways: (1) the identification of cis-acting patterning information within the Drosophila genome, as revealed by a lacZ reporter gene within the P element, and (2) the isolation of lethal mutations. We examined 3768 independent lines for the expression of lacZ in embryos and looked among these lines for lethal mutations affecting embryonic neurogenesis. This type of screen appears to be an effective way to find new loci that may play a role in the development of the Drosophila nervous system.

Asunto(s)

Elementos Transponibles de ADN , Drosophila melanogaster/genética , Animales , Evolución Biológica , Drosophila melanogaster/embriología , Embrión no Mamífero/análisis , Regulación de la Expresión Génica , Genes Letales , Vectores Genéticos , Mutación , Sistema Nervioso/embriología , Proteínas Recombinantes de Fusión/análisis , beta-Galactosidasa/análisis