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Michael Akam - One of the best experts on this subject based on the ideXlab platform.
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early embryo patterning in the grasshopper Schistocerca gregaria wingless decapentaplegic and caudal expression
Development, 2001Co-Authors: Peter K Dearden, Michael AkamAbstract:Although the molecular pathways that pattern the early embryo of Drosophila melanogaster are well understood, how these pathways differ in other types of insect embryo remains largely unknown. We have examined the expression of three markers of early patterning in the embryo of the African plague locust Schistocerca gregaria, an orthopteran insect that displays a mode of embryogenesis very different from that of Drosophila . Transcripts of the caudal gene are expressed maternally and are present in all cells that aggregate to form the early embryonic rudiment. First signs of a posterior-to-anterior gradient in the levels of caudal transcript appear in the early heart-stage embryo, shortly before gastrulation. This gradient rapidly resolves to a defined expression domain marking segment A11. The decapentaplegic ( dpp ) gene, which encodes a transforming growth factor β family ligand, is first expressed in a circle of cells that delimit the margins of the embryonic primordium, where embryonic and extra-embryonic tissues abut. Patterned transcription of wingless reveals that the first segments are delineated in the Schistocerca embryo substantially earlier than previously thought, at least 14-16 hours before the onset of engrailed expression. By the late heart-stage, gnathal and thoracic segments are all defined. Thus, with respect to the molecular patterning of segments, the short germ Schistocerca embryo differs little from intermediate germ embryos. The expression of these marker genes suggests that embryonic pattern formation in the grasshopper occurs as cells move together to form the blastodisc.
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A role for Fringe in segment morphogenesis but not segment formation in the grasshopper, Schistocerca gregaria
Development genes and evolution, 2000Co-Authors: Peter K Dearden, Michael AkamAbstract:Studies of somitogenesis in vertebrates have identified a number of genes that are regulated by a periodic oscillator that patterns the pre-somitic mesoderm. One of these genes, hairy, is homologous to a Drosophila segmentation gene that also shows periodic spatial expression. This, and the periodic expression of a zebrafish homologue of hairy during somitogenesis, has suggested that insect segmentation and vertebrate somitogenesis may use similar molecular mechanisms and possibly share a common origin. In chicks and mice expression of the lunatic fringe gene also oscillates in the presomitic mesoderm. Fringe encodes an extracellular protein that regulates Notch signalling. This, and the finding that mutations in Notch or its ligands disrupt somite patterning, suggests that Notch signalling plays an important role in vertebrate somitogenesis. Although Notch signalling is not known to play a role in the formation of segments in Drosophila, we reasoned that it might do so in other insects such as the grasshopper, where segment boundaries form between cells, not between syncytial nuclei as they do in Drosophila. Here we report the cloning of a single fringe gene from the grasshopper Schistocerca. We show that it is not detectably expressed in the forming trunk segments of the embryo until after segment boundaries have formed. We conclude that fringe is not part of the mechanism that makes segments in Schistocerca. Thereafter it is expressed in a pattern which shows that it is a downstream target of the segmentation machinery and suggests that it may play a role in segment morphogenesis. Like its Drosophila counterpart, Schistocerca fringe is also expressed in the eye, in rings in the legs, and during oogenesis, in follicle cells.
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Maternal expression and early zygotic regulation of the Hox3/zen gene in the grasshopper Schistocerca gregaria
Evolution & development, 2000Co-Authors: Peter K Dearden, Miodrag Grbić, Francesco Falciani, Michael AkamAbstract:In insects, a key step in the early patterning of the egg is to distinguish the primordium of the embryo proper from those regions that will form extra-embryonic membranes. In Drosophila, where these processes are well understood, the structure of the extra-embryonic membranes is highly derived. The distinct amnion and serosa typical of lower insects is replaced by a single, fused, and much reduced membrane, the amnioserosa, which never secretes an embryonic cuticle. We have used the Zen gene as a marker to study the formation of the extra-embryonic membranes, and other aspects of early embryonic patterning, in the grasshopper Schistocerca gregaria (African Plague Locust). Zen genes are derived from Hox genes, but in Drosophila they appear to have lost any role in patterning the A/P axis of the embryo; instead, they are involved in D/V patterning and the specification of the extra-embryonic membranes. We show that the Schistocerca zen gene is expressed during embryogenesis in three distinct phases. The first of these is during cleavage, when Sgzen is transiently expressed in all energids that reach the cell surface. The second phase of expression initiates in a ring of "necklace cells" that surround the forming embryo, and demarcate the boundary between the amnion and serosa. This leads to expression throughout the serosa. The final phase of expression is in the amnion, after this has separated from the serosa. This complex pattern implies that the role of Sgzen in Schistocerca is not limited solely to the specification of cell identity in the extra-embryonic membranes. We also report that the Schistocerca zen gene is expressed maternally, unlike its Drosophila and Tribolium counterparts. A distinct maternal transcript, and maternal Zen protein, accumulate in the developing oocyte from early post-meiotic stages. They remain uniformly distributed in the oocyte cytoplasm until late vitellogenic stages, when the protein and RNA become somewhat concentrated at the egg cortex and in the posterior polar cap of the oocyte, probably by passive exclusion from the yolk. The cytoplasmic localization of Sgzen protein in the oocyte, and at some stages during embryogenesis, implies that nuclear exclusion of this transcription factor is specifically controlled.
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homeotic gene expression in the locust Schistocerca an antibody that detects conserved epitopes in ultrabithorax and abdominal a proteins
Developmental Genetics, 1994Co-Authors: Robert N Kelsh, Robert O J Weinzierl, Robert A H White, Michael AkamAbstract:To investigate what role homeotic genes may play in morphological evolution, we are comparing homeotic gene expression in two very different insects, Drosophila (Diptera) and Schistocerca (Orthoptera). In this paper we describe a monoclonal antibody, FP6.87, that recognizes the products of both the Ultrabithorax (Ubx) and abdominal-A (abd-A) genes in Drosophila, via an epitope common to the carboxy terminal region of these two proteins. This antibody recognizes nuclear antigens present in the posterior thorax and abdomen of Schistocerca. We infer that it recognizes the Schistocerca homolog of UBX protein, and probably also of ABD-A. As the distribution of Schistocerca ABD-A protein is already known, we can use this reagent to map the expression of Schistocerca UBX in the thorax and anterior abdomen, where ABD-A is not expressed. Both the general domain, and many of the details, of UBX expression are remarkably conserved compared with Drosophila. Thus UBX expression extends back from T2 in the ectoderm (including the CNS), but only from A1 in the mesoderm. As noted for other bithorax complex genes in Schistocerca, expression begins in the abdomen, at or shortly before the time of segmentation. It only later spreads anteriorly to the thorax. For much of embryogenesis, the expression of UBX in the thoracic epidermis is largely restricted to the T3 limb. In this limb, UBX is strikingly regulated, in a complex pattern that reflects limb segmentation. Reviewing these and earlier observations, we conclude that evolutionary changes affect both the precise regulation of homeotic genes within segments, and probably also the spectrum of downstream genes that respond to homeotic gene expression in a given tissue. Overall domains of homeotic gene expression appear to be well conserved between different insect groups, though a change in the extent and timing of homeotic gene expression may underlie the modification of the posterior abdomen in different insect groups.
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An analysis of abdominal-B expression in the locust Schistocerca gregaria
Development (Cambridge England), 1993Co-Authors: Robert N Kelsh, Iain Dawson, Michael AkamAbstract:We have cloned a homologue of the homeotic gene Abdominal-B from the locust Schistocerca gregaria and raised antibodies against the homeodomain and C-terminal flanking region of the encoded protein. This antibody stains the posterior abdomen of the developing Schistocerca embryo from 26% of development onwards, a stage when only the anterior of the abdomen is visibly segmented. By the time segmentation has reached the posterior of the abdomen, ABD-B protein is detectable only in the terminal segment (A11). Expression extends anteriorly as development proceeds to include the epidermis of all segments from A8p to A11, including the genital appendages of A9 and A10. The anal cerci, generally regarded as appendages of A11, remain unstained. This expression domain corresponds to the region within which the Abd-B r function of the Drosophila Abd-B gene is expressed. We detect no expression corresponding to the Abd-B m function in Drosophila.
Hans-hinrich Kaatz - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the mitochondrial genome of Schistocerca gregaria gregaria (Orthoptera: Acrididae)
Biological Journal of the Linnean Society, 2010Co-Authors: Silvio Erler, Hans-jörg Ferenz, Robin F. A. Moritz, Hans-hinrich KaatzAbstract:In the present study, we present the full sequence of the mitochondrial genome of the African desert locust Schistocerca gregaria gregaria. The size of 15625 bp reported matches very well with mitochondrial genomes of other Orthopteriodea. The mitochondrial genome comprises 13 protein-coding genes, two ribosomal RNAs and 22 t-RNAs with two t-RNA (trnD and trnK) rearrangements that are typical for the taxon Caelifera. We compared the sequence with 12 mitochondrial genes of Schistocerca gregaria flaviventris and Schistocerca americana and used some of these data to construct phylogenetic trees, which confirm the close relationship between the two subspecies S. g. flaviventris and S. g. gregaria. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 296–305. ADDITIONAL KEYWORDS: gene organization – phylogeny – Schistocerca americana – subspecies.
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Isolation and characterization of nine polymorphic microsatellite loci from the desert locust, Schistocerca gregaria
Molecular Ecology Notes, 2007Co-Authors: Hans-hinrich Kaatz, Hans-jörg Ferenz, B. Langer, Robin F. A. MoritzAbstract:Because of the scarcity of polymorphic genetic markers, only a few genetic studies on the population structure of the desert locust, Schistocerca gregaria, have been carried out. We isolated and characterized nine polymorphic dinucleotide microsatellite loci. These markers were evaluated using individuals from Niger and Senegal. Seven of these microsatellite markers are also applicable to the nongregarious subspecies Schistocerca gregaria flaviventris. Cross-species applicability was limited to one of the loci in the sister species S. americana and in the locust Locusta migratoria.
Scott D. Kirkton - One of the best experts on this subject based on the ideXlab platform.
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Effect of gravidity on jump performance and muscle physiology in the American locust
The FASEB Journal, 2013Co-Authors: John P. Carroll, Scott D. KirktonAbstract:The effect of gravidity (or load) on jumping is not well documented. Lizards produced shorter jumps when a load equal to 30% of body mass was attached. However in Schistocerca americana grasshopper...
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Effects of oviposition on jump performance in the American locust (Schistocerca americana)
The FASEB Journal, 2008Co-Authors: Kaitlin Arntzen, Scott D. KirktonAbstract:Life history changes, such as ontogeny or gravidity, can alter energetic demands associated with animal locomotion. By studying how locomotory performance in the American locust (Schistocerca ameri...
Robin F. A. Moritz - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the mitochondrial genome of Schistocerca gregaria gregaria (Orthoptera: Acrididae)
Biological Journal of the Linnean Society, 2010Co-Authors: Silvio Erler, Hans-jörg Ferenz, Robin F. A. Moritz, Hans-hinrich KaatzAbstract:In the present study, we present the full sequence of the mitochondrial genome of the African desert locust Schistocerca gregaria gregaria. The size of 15625 bp reported matches very well with mitochondrial genomes of other Orthopteriodea. The mitochondrial genome comprises 13 protein-coding genes, two ribosomal RNAs and 22 t-RNAs with two t-RNA (trnD and trnK) rearrangements that are typical for the taxon Caelifera. We compared the sequence with 12 mitochondrial genes of Schistocerca gregaria flaviventris and Schistocerca americana and used some of these data to construct phylogenetic trees, which confirm the close relationship between the two subspecies S. g. flaviventris and S. g. gregaria. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 296–305. ADDITIONAL KEYWORDS: gene organization – phylogeny – Schistocerca americana – subspecies.
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Isolation and characterization of nine polymorphic microsatellite loci from the desert locust, Schistocerca gregaria
Molecular Ecology Notes, 2007Co-Authors: Hans-hinrich Kaatz, Hans-jörg Ferenz, B. Langer, Robin F. A. MoritzAbstract:Because of the scarcity of polymorphic genetic markers, only a few genetic studies on the population structure of the desert locust, Schistocerca gregaria, have been carried out. We isolated and characterized nine polymorphic dinucleotide microsatellite loci. These markers were evaluated using individuals from Niger and Senegal. Seven of these microsatellite markers are also applicable to the nongregarious subspecies Schistocerca gregaria flaviventris. Cross-species applicability was limited to one of the loci in the sister species S. americana and in the locust Locusta migratoria.
Hans-jörg Ferenz - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the mitochondrial genome of Schistocerca gregaria gregaria (Orthoptera: Acrididae)
Biological Journal of the Linnean Society, 2010Co-Authors: Silvio Erler, Hans-jörg Ferenz, Robin F. A. Moritz, Hans-hinrich KaatzAbstract:In the present study, we present the full sequence of the mitochondrial genome of the African desert locust Schistocerca gregaria gregaria. The size of 15625 bp reported matches very well with mitochondrial genomes of other Orthopteriodea. The mitochondrial genome comprises 13 protein-coding genes, two ribosomal RNAs and 22 t-RNAs with two t-RNA (trnD and trnK) rearrangements that are typical for the taxon Caelifera. We compared the sequence with 12 mitochondrial genes of Schistocerca gregaria flaviventris and Schistocerca americana and used some of these data to construct phylogenetic trees, which confirm the close relationship between the two subspecies S. g. flaviventris and S. g. gregaria. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 296–305. ADDITIONAL KEYWORDS: gene organization – phylogeny – Schistocerca americana – subspecies.
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Isolation and characterization of nine polymorphic microsatellite loci from the desert locust, Schistocerca gregaria
Molecular Ecology Notes, 2007Co-Authors: Hans-hinrich Kaatz, Hans-jörg Ferenz, B. Langer, Robin F. A. MoritzAbstract:Because of the scarcity of polymorphic genetic markers, only a few genetic studies on the population structure of the desert locust, Schistocerca gregaria, have been carried out. We isolated and characterized nine polymorphic dinucleotide microsatellite loci. These markers were evaluated using individuals from Niger and Senegal. Seven of these microsatellite markers are also applicable to the nongregarious subspecies Schistocerca gregaria flaviventris. Cross-species applicability was limited to one of the loci in the sister species S. americana and in the locust Locusta migratoria.
