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Drosophila Embryo (drosophila + embryo)

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Life Sciences	100%

Selected Abstracts

vrille is required to ensure tracheal integrity in Drosophila embryo

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2010
Sébastien Szuplewski
The Drosophila bZIP transcription factor Vrille (VRI) is required for growth, circadian clock regulation and metamorphosis. We identified here a new facet of vrille (vri) function and show that it is required for tracheal development. We show that, in the embryo, VRI is expressed in a complex and dynamic pattern and is found in amnioserosa, subdomains of the developing gut and in trachea cells. We also show that, as expected, the protein is nuclear. We then asked whether VRI was involved in morphogenetic processes such as gut and tracheal development. We therefore investigated the development of these tissues in vri mutants, and although we did not observe any defects in gut morphology, we identified differentiation defects that affect tracheal integrity. Most of the defects were observed after stage 14 and affect all branches, resulting in branch breaks, abnormal branching and elongation. [source]

Differing strategies for forming the arthropod body plan: Lessons from Dpp, Sog and Delta in the fly Drosophila and spider Achaearanea

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 4 2008
Hiroki Oda
In the insect Drosophila embryo, establishment of maternal transcription factor gradients, rather than cell,cell interactions, is fundamental to patterning the embryonic axes. In contrast, in the chelicerate spider embryo, cell,cell interactions are thought to play a crucial role in the development of the embryonic axes. A grafting experiment by Holm using spider eggs resulted in duplication of the embryonic axes, similar to the Spemann's organizer experiment using amphibian eggs. Recent work using the house spider Achaearanea tepidariorum has demonstrated that the homologs of decapentaplegic (dpp), short gastrulation (sog) and Delta, which encode a bone morphogenetic protein (BMP)-type ligand, its antagonist and a Notch ligand, respectively, are required in distinct aspects of axis formation. Achaearanea Dpp appears to function as a symmetry-breaking signal, which could account for Holm's results to some extent. Experimental findings concerning Achaearanea sog and Delta have highlighted differences in the mechanisms underlying ventral and posterior development between Drosophila and Achaearanea. Achaearanea ventral patterning essentially depends on sog function, in contrast to the Drosophila patterning mechanism, which is based on the nuclear gradient of Dorsal. Achaearanea posterior (or opisthosomal) patterning relies on the function of the caudal lobe, which develops from cells surrounding the blastopore through progressive activation of Delta-Notch signaling. In this review, we describe the differing strategies for forming the arthropod body plan in the fly and spider, and provide a perspective towards understanding the relationship between the arthropod and vertebrate body plans. [source]

Microtubule-dependent organization of subcortical microfilaments in the early Drosophila embryo

DEVELOPMENTAL DYNAMICS, Issue 3 2007
Maria Giovanna Riparbelli
Abstract Dynamic alterations in the spatial organization of cytoskeletal elements constitute a prominent morphological feature of the early, syncytial stages of embryogenesis in Drosophila. Here, we describe and characterize the dynamic behavior of cytoplasmic, subcortical microfilaments, which form a series of nucleus-associated structures, at different phases of the simultaneous nuclear division cycles characteristic of early Drosophila embryos. Remodeling of the cytoplasmic microfilament arrays takes place in parallel to the established cyclic reorganization of cortical microfilament structures. We provide evidence that the cortical and subcortical microfilament populations organize independently of each other, and in response to distinct instructive cues. Specifically, formation of subcortical microfilament structures appears to rely on, and spatially mirror, the organization of polarized microtubule arrays, while cortical microfilament restructuring constitutes a centrosome-dependent process. Genetic analysis identifies a requirement for SCAR, a key mediator of Arp2/3-based microfilament dynamics, in organization of subcortical microfilament structures. Developmental Dynamics 236:662,670, 2007. © 2007 Wiley-Liss, Inc. [source]

Methanol exposure interferes with morphological cell movements in the Drosophila embryo and causes increased apoptosis in the CNS

DEVELOPMENTAL NEUROBIOLOGY, Issue 3 2004
Dervla M. Mellerick
Abstract Despite the significant contributions of tissue culture and bacterial models to toxicology, whole animal models for developmental neurotoxins are limited in availability and ease of experimentation. Because Drosophila is a well understood model for embryonic development that is highly accessible, we asked whether it could be used to study methanol developmental neurotoxicity. In the presence of 4% methanol, approximately 35% of embryos die and methanol exposure leads to severe CNS defects in about half those embryos, where the longitudinal connectives are dorsally displaced and commissure formation is severely reduced. In addition, a range of morphological defects in other germ layers is seen, and cell movement is adversely affected by methanol exposure. Although we did not find any evidence to suggest that methanol exposure affects the capacity of neuroblasts to divide or induces inappropriate apoptosis in these cells, in the CNS of germ band retracted embryos, the number of apoptotic nuclei is significantly increased in methanol-exposed embryos in comparison to controls, particularly in and adjacent to the ventral midline. Apoptosis contributes significantly to methanol neurotoxicity because embryos lacking the cell death genes grim, hid, and reaper have milder CNS defects resulting from methanol exposure than wild-type embryos. Our data suggest that when neurons and glia are severely adversely affected by methanol exposure, the damaged cells are cleared by apoptosis, leading to embryonic death. Thus, the Drosophila embryo may prove useful in identifying and unraveling mechanistic aspects of developmental neurotoxicity, specifically in relation to methanol toxicity. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 308,318, 2004 [source]

Calmodulin and profilin coregulate axon outgrowth in Drosophila

DEVELOPMENTAL NEUROBIOLOGY, Issue 1 2001
You-Seung Kim
Abstract Coordinated regulation of actin cytoskeletal dynamics is critical to growth cone movement. The intracellular molecules calmodulin and profilin actively regulate actin-based motility and participate in the signaling pathways used to steer growth cones. Here we show that in the developing Drosophila embryo, calmodulin and profilin convey complimentary information that is necessary for appropriate growth cone advance. Reducing calmodulin activity by expression of a dominant inhibitor (KA) stalls axon extension of pioneer neurons within the CNS, while a partial loss of profilin function decreases extension of motor axons in the periphery. Yet, surprisingly, when calmodulin and profilin are simultaneously reduced, the ability of both CNS pioneer axons and motor axons to extend beyond the choice points is restored. In the CNS, at the time when growth cones must decide whether to cross or not to cross the midline, a reduction in calmodulin and/or roundabout signaling causes axons to cross the midline inappropriately. These inappropriate crossings are suppressed when profilin activity is simultaneously reduced. Interestingly, the mutual suppression of calmodulin and profilin activity requires a minimal level of profilin. In KA combinations with profilin null alleles, defects in axon extension and midline guidance are synergistically enhanced rather than suppressed. Together, our data indicate that the growth cone must coordinate the activity of both calmodulin and profilin in order to advance past selected choice points, including those dictating midline crossovers. © 2001 John Wiley & Sons, Inc. J Neurobiol 47: 26,38, 2001 [source]

A Drosophila melanogaster cell line (S2) facilitates post-genome functional analysis of receptors and ion channels

BIOESSAYS, Issue 11 2002
Paula R. Towers
The complete sequencing of the genome of the fruit fly Drosophila melanogaster offers the prospect of detailed functional analysis of the extensive gene families in this genetic model organism. Comprehensive functional analysis of family members is facilitated by access to a robust, stable and inducible expression system in a fly cell line. Here we show how the Schneider S2 cell line, derived from the Drosophila embryo, provides such an expression system, with the bonus that radioligand binding studies, second messenger assays, ion imaging, patch-clamp electrophysiology and gene silencing can readily be applied. Drosophila is also ideal for the study of new control strategies for insect pests since the receptors and ion channels that many new animal health drugs and crop protection chemicals target can be expressed in this cell line. In addition, many useful orthologues of human disease genes are emerging from the Drosophila genome and the study of their functions and interactions is another area for postgenome applications of S2 cell lines. BioEssays 24:1066,1073, 2002. © 2002 Wiley-Periodicals, Inc. [source]

Probing events with single molecule sensitivity in zebrafish and Drosophila embryos by fluorescence correlation spectroscopy

DEVELOPMENTAL DYNAMICS, Issue 12 2009
Xianke Shi
Abstract Zebrafish and Drosophila are animal models widely used in developmental biology. High-resolution microscopy and live imaging techniques have allowed the investigation of biological processes down to the cellular level in these models. Here, using fluorescence correlation spectroscopy (FCS), we show that even processes on a molecular level can be studied in these embryos. The two animal models provide different advantages and challenges. We first characterize their autofluorescence pattern and determine usable penetration depth for FCS especially in the case of zebrafish, where tissue thickness is an issue. Next, the applicability of FCS to study molecular processes is shown by the determination of blood flow velocities with high spatial resolution and the determination of diffusion coefficients of cytosolic and membrane-bound enhanced green fluorescent protein,labeled proteins in different cell types. This work provides an approach to study molecular processes in vivo and opens up the possibility to relate these molecular processes to developmental biology questions. Developmental Dynamics 238:3156,3167, 2009. © 2009 Wiley-Liss, Inc. [source]

Microtubule-dependent organization of subcortical microfilaments in the early Drosophila embryo

Screening for synaptic defects revealed a locus involved in presynaptic and postsynaptic functions in Drosophila embryos

DEVELOPMENTAL NEUROBIOLOGY, Issue 2 2001
Etsuko Takasu-Ishikawa
Abstract To identify genes involved in synaptic functions, we screened lethal enhancer trap lines by monitoring synaptic activities at the neuromuscular junction in Drosophila embryos. It was found that MY7919, thus isolated, has moderate defects in both pre- and postsynaptic functions. The mean amplitudes of spontaneous as well as evoked synaptic currents were smaller than those in wild-type. The failure rate was higher than normal at any given concentration of external Ca2+, indicating that presynaptic functions were impaired. In addition, the mean amplitude of miniature synaptic currents was smaller, and the unitary current amplitudes of junctional glutamate receptor channels were slightly but significantly smaller. Thus, postsynaptic functions were also altered. The gene was cloned and found to be identical to the previously reported apontic (=tracheae defective) locus, which is believed to be a transcription factor expressed in the central nervous system (CNS) as well as in the head, tracheae, and heart. Immunohistochemical analysis using an antiapontic antibody revealed that the protein is localized to nuclei. Null alleles of the apontic locus were obtained by imprecise excision of the enhancer trap vector. Synaptic activities in null mutants were not different from those of the original allele, even though null homozygotes had uncontracted ventral nerve cords and more severe behavioral phenotypes. The morphology of the neuromuscular junction of the null mutant was qualitatively similar to that of wild-type, with the presence of typical pre- and postsynaptic specializations, but with some suggestions of quantitative differences. This strategy for screening mutants with synaptic defects will reveal more genes directly or indirectly affecting synaptic transmission. © 2001 John Wiley & Sons, Inc. J Neurobiol 48: 101,119, 2001 [source]

Silencing of an abdominal Hox gene during early development is correlated with limb development in a crustacean trunk

EVOLUTION AND DEVELOPMENT, Issue 2 2010
Cheryl C. Hsia
SUMMARY We tested whether Artemia abd-A could repress limbs in Drosophila embryos, and found that although abd-A transcripts were produced, ABD-A protein was not. Similarly, developing Artemia epidermal cells showed expression of abd-A transcripts without accumulation of ABD-A protein. This finding in Artemia reveals a new variation in Hox gene function that is associated with morphological evolution. In this case, a HOX protein expression pattern is completely absent during early development, although the HOX protein is expressed at later stages in the central nervous system in a "homeotic-like" pattern. The combination of an absence of ABD-A protein expression in the Artemia limb primordia and the weak repressive function of Artemia UBX protein on the limb-promoting gene Dll are likely to be two reasons why homonomous limbs develop throughout the entire Artemia trunk. [source]

Evolutionary and functional analysis of the tailless enhancer in Musca domestica and Drosophila melanogaster

EVOLUTION AND DEVELOPMENT, Issue 1 2006
Naomi S. Wratten
SUMMARY To further understand the evolutionary dynamics of the regulatory interactions underlying development, we expand on our previous analysis of hunchback and compare the structure and function of the tailless enhancer between Musca domestica and Drosophila melanogaster. Our analysis shows that although the expression patterns and functional protein domains of tll are conserved between Musca and Drosophila, the enhancer sequences are unalignable. Upon closer investigation, we find that these highly diverged enhancer sequences encode the same regulatory information necessary for Bicoid, Dorsal, and the terminal system to drive tll expression. The binding sites for these transcription factors differ in the sequence, number, spacing, and position between the Drosophila and Musca tll enhancers, and we were unable to establish homology between binding sites from each species. This implies that the Musca and Drosophila Bcd-binding sites have evolved de novo in the 100 million years since these species diverged. However, in transgenic Drosophila embryos the Musca tll enhancer is able to drive the same expression pattern as endogenous Drosophila tll. Therefore, during the rapid evolution of enhancer sequences individual binding sites are continually lost and gained, but the transcriptional output is maintained by compensatory mutations in cis and in trans. [source]

Functional analysis of the sea urchin-derived arylsulfatase (Ars)-element in mammalian cells

GENES TO CELLS, Issue 9 2006
Satoshi Watanabe
An insulator is a DNA sequence that has both enhancer-blocking activity, through its ability to modify the influence of neighboring cis -acting elements, and a barrier function that protects a transgene from being silenced by surrounding chromatin. Previously, we isolated and characterized a 582-bp-long element from the sea urchin arylsulfatase gene (Ars). This Ars -element was effective in sea urchin and Drosophila embryos and in plant cells. To investigate Ars -element activity in mammalian cells, we placed the element between the cytomegalovirus enhancer and a luciferase (luc) expression cassette. In contrast to controls lacking the Ars -element, NIH3T3 and 293T cells transfected with the element-containing construct displayed reduced luciferase activities. The Ars -element therefore acts as an enhancer-blocking element in mammalian cells. We assessed the barrier activity of the Ars -element using vectors in which a luc expression cassette was placed between two elements. Transfection experiments demonstrated that luc activity in these vectors was approximately ten-fold higher than in vectors lacking elements. Luc activities were well maintained even after 12 weeks in culture. Our observations demonstrate that the Ars -element has also a barrier activity. These results indicated that the Ars -element act as an insulator in mammalian cells. [source]