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  • 1
    ISSN: 1432-041X
    Keywords: Key words Brain development ; Axonal scaffold ; Extradenticle ; Homothorax ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  During early brain development in Drosophila a highly stereotyped pattern of axonal scaffolds evolves by precise pioneering and selective fasciculation of neural fibers in the newly formed brain neuromeres. Using an axonal marker, Fasciclin II, we show that the activities of the extradenticle (exd) and homothorax (hth) genes are essential to this axonal patterning in the embryonic brain. Both genes are expressed in the developing brain neurons, including many of the tract founder cluster cells. Consistent with their expression profiles, mutations of exd and hth strongly perturb the primary axonal scaffolds. Furthermore, we show that mutations of exd and hth result in profound patterning defects of the developing brain at the molecular level including stimulation of the orthodenticle gene and suppression of the empty spiracles and cervical homeotic genes. In addition, expression of a Drosophila Pax6 gene, eyeless, is significantly suppressed in the mutants except for the most anterior region. These results reveal that, in addition to their homeotic regulatory functions in trunk development, exd and hth have important roles in patterning the developing brain through coordinately regulating various nuclear regulatory genes, and imply molecular commonalities between the developmental mechanisms of the brain and trunk segments, which were conventionally considered to be largely independent.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 210 (2000), S. 483-492 
    ISSN: 1432-041X
    Keywords: Key words  Dfd ; Scr ; Antp ; Ubx ; abd-A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Hox genes are known to control the identity of serially repeated structures in arthropods and vertebrates. We analyzed the expression pattern of the Hox genes Deformed (Dfd), Sex combs reduced (Scr), Antennapedia (Antp), and Ultrabithorax/abdominal-A (Ubx/abd-A) from the honey bee Apis mellifera. We also cloned a cDNA with the complete coding region of the Antennapedia gene from Apis. Comparison with Antp proteins from other insect species revealed several regions of homology. The expression patterns of the isolated Hox genes from Apis showed that the original expression patterns of Dfd, Scr, and Antp appear between late blastoderm and early germ band stage in a temporal and spatial sequence. Each of them shows up as a belt, spanning approximately two segment anlagen, Dfd in the anterior gnathal region, Scr in the posterior gnathal and anterior thoracic region, and Antp in the thoracic region. Following expansion of the Antp domain in the abdomen as a gradient towards the posterior, Ubx/abd-A expression appears laterally in the abdomen. During gastrulation and in the germ band stage the domains of strong expression do not overlap any more, but touch each other. After gastrulation the borders of the expression domains partly correlate with parasegment and partly with segment boundaries. Laterally, gaps between the domain of each gene may show no expression of any of the genes examined.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 201 (1992), S. 235-242 
    ISSN: 1432-041X
    Keywords: Honeybee ; Embryogenesis ; Homeotic genes ; Deformed ; Antibody staining
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have raised antiserum against part of the Deformed (Dfd) protein of the honeybee and describe here the expression pattern of the Dfd protein during honeybee embryogenesis. Dfd protein is first stained in the prospective gnathal region of the cellular blastoderm. This circumferential band corresponds to the distribution of Dfd mRNA described earlier, and to the blastodermal Dfd expression pattern in Drosophila. Using an antibody against the engrailed (en) protein of Drosophila, we found that at the beginning of gastrulation Dfd expression in the honeybee, as in Drosophila, is restricted to the future intercalary, mandibular and maxillary segments. During gastrulation, the mesodermal nuclei loose the Dfd label gradually from anterior to posterior, and in the ectoderm the most posterior ventral cells loose Dfd while retaining en staining; thus, in contrast to what has been described for Drosophila, the posterior Dfd expression border seems to move forward ventrally to the parasegmental boundary within the maxillary segment. In the late germ band, the lateral tips of the Dfd-expressing band are connected across the dorsal side by a row of amnion cells with strongly staining large nuclei. After dorsal closure, a narrow stripe of Dfd-staining dorsal cells behind the neck region may indicate that the maxillary segment contributes to the dorsal body wall posterior to the head capsule. Thus, apart from some minor deviations, the Dfd expression pattern in the honeybee strongly resembles that in Drosophila prior to head involution. This is compatible with the assumption that head involution (which is a special adaption in higher dipterans) ensues after a rather conserved course of early head development in which Dfd appears to play a basic role.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 267 (1990), S. 245-249 
    ISSN: 0014-5793
    Keywords: Apis mellifera ; Drosophila melanogaster ; Elongation factor ; Genomic sequence ; Protein synthesis ; Translation
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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