The Experts below are selected from a list of 7131 Experts worldwide ranked by ideXlab platform
Diethard Tautz - One of the best experts on this subject based on the ideXlab platform.
-
The role of the Segmentation Gene hairy in Tribolium
Development Genes and Evolution, 2008Co-Authors: Manuel Aranda, Henrique Marques-souza, Till Bayer, Diethard TautzAbstract:Hairy stripes in Tribolium are Generated during blastoderm and germ band extension, but a direct role for Tc - h in trunk Segmentation was not found. We have studied here several aspects of hairy function and expression in Tribolium , to further elucidate its role. First, we show that there is no functional redundancy with other hairy paralogues in Tribolium . Second, we cloned the hairy orthologue from Tribolium confusum and show that its expression mimics that of Tribolium castaneum , implying that stripe expression should be functional in some way. Third, we show that the dynamics of stripe formation in the growth zone is not compatible with an oscillatory mechanism comparable to the one driving the expression of hairy homologues in vertebrates. Fourth, we use parental RNAi experiments to study Tc - h function and we find that mandible and labium are particularly sensitive to loss of Tc - h , reminiscent of a pair-rule function in the head region. In addition, lack of Tc - h leads to cell death in the gnathal region at later embryonic stages, resulting in a detachment of the head. Cell death patterns are also altered in the midline. Finally, we have analysed the effect of Tc-h knockdown on two of the target Genes of hairy in Drosophila , namely fushi tarazu and paired . We find that the trunk expression of Tc-h is required to regulate Tc-ftz , although Tc-ftz is itself also not required for trunk Segmentation in Tribolium . Our results imply that there is considerable divergence in hairy function between Tribolium and Drosophila .
-
a Segmentation Gene in tribolium produces a polycistronic mrna that codes for multiple conserved peptides
Cell, 2006Co-Authors: Joel Savard, Henrique Marquessouza, Manuel Aranda, Diethard TautzAbstract:Summary Segmentation Genes in insects are required for Generating the subdivisions of the early embryo. We describe here a new member of the gap family of Segmentation Genes in the flour beetle Tribolium , mille-pattes ( mlpt ). mlpt knockdown leads to transformation of the abdominal segments into thoracic segments, providing embryos with up to ten pairs of legs. We show that there are crossregulatory interactions between mlpt and the known gap Genes in Tribolium , suggesting that mlpt is itself a gap Gene. The mlpt Gene reveals an unusual structure, as it encodes a polycistronic mRNA that codes for four peptides. mlpt appears to be the prototype of this previously unknown Gene structure in eukaryotes, as we find homologous Genes with the same polycistronic arrangement in other insect genomes as well.
-
Segmentation Gene expression in the mothmidge clogmia albipunctata diptera psychodidae and other primitive dipterans
Development Genes and Evolution, 1999Co-Authors: Klaus B Rohr, Diethard Tautz, Klaus SanderAbstract:To obtain a clearer understanding of the evolutionary transition between short- and long-germ modes of embryoGenesis in insects, we studied the expression of two gap Genes hunchback (hb) and Kruppel (Kr) as well as the pair-rule Gene even-skipped (eve) in the dipteran Clogmia albipunctata (Nematocera, Psychodidae). This species has features of both short- and long-germ mode of embryoGenesis. In Clogmia hb expression deviates from that known in Drosophila in two main respects: (1) it shows an extended dorsal domain that is linked to the large serosa anlage, and (2) it shows a terminal expression in the proctodeal region. These expression patterns are reminiscent of the hb expression pattern in the beetle Tribolium, which has a short germ mode of embryoGenesis. Kruppel expression, on the other hand, was found to be rather similar to the Drosophila expression, both at early and late stages. eve expression starts with six stripes formed at blastoderm stage, while the seventh is only formed after the onset of gastrulation and germband extension. Surprisingly, no segmental secondary Eve stripes could be observed in Clogmia although such segmental stripes are known from higher dipterans, beetles and hymenopterans. We therefore also studied another nematoceran, Coboldia, to address this question and found that some segmental stripes form by intercalation as in Drosophila, although belatedly. Our results suggest that Clogmia embryoGenesis, both with respect to morphological and molecular characteristics represents an intermediate between the long-germ mode known from higher dipterans such as Drosophila, and the short-germ mode found in more ancestral insects.
-
conserved and divergent expression aspects of the drosophila Segmentation Gene hunchback in the short germ band embryo of the flour beetle tribolium
Development, 1995Co-Authors: Christian Wolff, Gerald Glaser, Ralf J Sommer, Reinhard Schroder, Diethard TautzAbstract:The Segmentation Gene hunchback (hb) plays a central role in determining the anterior-posterior pattern in the Drosophila embryo. We have cloned the homologue of hb from the flour beetle Tribolium and show that, on the basis of its expression pattern, most of its functions seem to be conserved between these two species. Like Drosophila, Tribolium has a maternal hb expression that appears to be under translational control by a factor at the posterior pole of the embryo. The maternal expression is followed by a zygotic expression in the region of the developing head and thoracic segments. During germ band extension, a posterior expression domain appears that is likely to be homologous to the posterior blastoderm expression of hb in Drosophila. These observations suggest that hb may have the same functions in early Drosophila and Tribolium development, despite the different types of embryoGenesis in these two species (long versus short germ development). One differing aspect of hb expression in Tribolium concerns a structure that is not present in Drosophila, namely the serosa. An hb expression domain at the anterior pole precisely demarcates the border between the extraembryonic serosa and the embryonic field in the Tribolium embryo at an early stage, and hb protein remains expressed in the serosa cells until the end of embryoGenesis.
-
differential regulation of target Genes by different alleles of the Segmentation Gene hunchback in drosophila
Genetics, 1994Co-Authors: Martin Hulskamp, Wolfgang Lukowitz, Gerald Glaser, A Beermann, Diethard TautzAbstract:hunchback (hb) is a key regulatory Gene in the early Segmentation Gene hierarchy of Drosophila. It codes for a transcription factor of the Cys2-His2 zinc finger type and shows two separate zinc finger domains in its coding region. hb forms a morphoGenetic gradient in the middle of the embryo that is required for setting the spatial boundaries of several target Genes. We have analyzed the molecular lesions found in the different hb alleles and have studied the differential effects of these alleles on a number of such target Genes. We find that in mutants in which the HB protein lacks a functional second finger domain, the regulation of the target Genes Kruppel (Kr) and knirps (kni) is differentially affected. While this domain is required for the correct regulation of Kr, it is not necessary for the repression of kni. Furthermore, mutations affecting this domain lead to a decreased protein stability. The integration of the expression pattern of target Genes was found to be distorted in a second class of mutants between the two finger domains which lead to gain of function or neomorphic phenotypes. The effects of these mutations were studied in detail and it was found that they fall into two classes, the first one interfering with the function of the maternal hb product, the second leading to a delayed Segmentation. The function of the latter class appears to be linked to the secondary expression of hb in the parasegment 4 (PS4) stripe at blastoderm stage.
John Reinitz - One of the best experts on this subject based on the ideXlab platform.
-
natural variation of the expression pattern of the Segmentation Gene even skipped in melanogaster
Developmental Biology, 2015Co-Authors: Pengyao Jiang, Michael Ludwig, Martin Kreitman, John ReinitzAbstract:The evolution of canalized traits is a central question in evolutionary biology. Natural variation in highly conserved traits can provide clues about their evolutionary potential. Here we investigate natural variation in a conserved trait-even-skipped (eve) expression at the cellular blastoderm stage of embryonic development in Drosophila melanogaster. Expression of the pair-rule Gene eve was quantitatively measured in three inbred lines derived from a natural population of D. melanogaster. One line showed marked differences in the spacing, amplitude and timing of formation of the characteristic seven-striped pattern over a 50-min period prior to the onset of gastrulation. Stripe 5 amplitude and the width of the interstripe between stripes 4 and 5 were both reduced in this line, while the interstripe distance between stripes 3 and 4 was increased. Engrailed expression in stage 10 embryos revealed a statistically significant increase in the length of parasegment 6 and a decrease in the length of parasegments 8 and 9. These changes are larger than those previously reported between D. melanogaster and D. pseudoobscura, two species that are thought to have diverged from a common ancestor over 25 million years ago. This line harbors a rare 448 bp deletion in the first intron of knirps (kni). This finding suggested that reduced Kni levels caused the deviant eve expression, and indeed we observed lower levels of Kni protein at early cycle 14A in L2 compared to the other two lines. A second of the three lines displayed an approximately 20% greater level of expression for all seven eve stripes. The three lines are each viable and fertile, and none display a Segmentation defect as adults, suggesting that early-acting variation in eve expression is ameliorated by developmental buffering mechanisms acting later in development. Canalization of the Segmentation pathway may reduce the fitness consequences of Genetic variation, thus allowing the persistence of mutations with unexpectedly strong Gene expression phenotypes.
-
erratum to quantitative dynamics and increased variability of Segmentation Gene expression in the drosophila kruppel and knirps mutants dev biol 376 2013 99 112
Developmental Biology, 2013Co-Authors: Svetlana Surkova, John Reinitz, E V Golubkova, Lena Panok, Lyudmila Mamon, Maria SamsonovaAbstract:and “Lack of tailless leads to an increase in expression variability in Drosophila embryos” [Dev. Biol. 377 (2013) 305–317] Hilde Janssensa, Anton Crombacha, Karl Richard Wottona, Damjan Cicin-Saina, Svetlana Surkovab, Chea Lu Limc, Maria Samsonovab, Michael Akamc, Johannes Jaegera,c,* aEMBL/CRG Research Unit in Systems Biology, CRG—Centre de Regulacio Genomica, and Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, 08003 Barcelona, Spain bDepartment of Computational Biology, Center for Advanced Studies, St. Petersburg State Polytechnical University, 29 Polytehnicheskaya Street, St. Petersburg 195251, Russia cDepartment of Zoology, Downing Street, Cambridge CB23EJ, UK The articles mentioned above were meant to be published back to back as companion papers in the same issue. *Corresponding authors. E-mail addresses: samson@spbcas.ru (M. Samsonova), yogi.jaeger@crg.eu, yoginho@gmail.com (J. Jaeger).
-
quantitative dynamics and increased variability of Segmentation Gene expression in the drosophila kruppel and knirps mutants
Developmental Biology, 2013Co-Authors: Svetlana Surkova, John Reinitz, E V Golubkova, Lena Panok, Lyudmila Mamon, Maria SamsonovaAbstract:Abstract Here we characterize the response of the Drosophila Segmentation system to mutations in two gap Genes, Kr and kni, in the form of single or double homozygotes and single heterozygotes. Segmentation Gene expression in these genotypes was quantitatively monitored with cellular resolution in space and 6.5 to 13 min resolution in time. As is the case with wild type, we found that Gene expression domains in the posterior portion of the embryo shift to the anterior over time. In certain cases, such as the gt posterior domain in Kr mutants, the shifts are significantly larger than is seen in wild type embryos. We also investigated the effects of Kr and kni on the variability of Gene expression. Mutations often produce variable phenotypes, and it is well known that the cuticular phenotype of Kr mutants is variable. We sought to understand the molecular basis of this effect. We find that throughout cycle 14A the relative levels of eve and ftz expression in stripes 2 and 3 are variable among individual embryos. Moreover, in Kr and kni mutants, unlike wild type, the variability in positioning of the posterior Hb domain and eve stripe 7 is not decreased or filtered with time. The posterior Gt domain in Kr mutants is highly variable at early times, but this variability decreases when this domain shifts in the anterior direction to the position of the neighboring Kni domain. In contrast to these findings, positional variability throughout the embryo does not decrease over time in double Kr;kni mutants. In heterozygotes the early expression patterns of Segmentation Genes resemble patterns seen in homozygous mutants but by the onset of gastrulation they become similar to the wild type patterns. Finally, we note that Gene expression levels are reduced in Kr and kni mutant embryos and have a tendency to decrease over time. This is a surprising result in view of the role that mutual repression is thought to play in the gap Gene system.
-
modeling of gap Gene expression in drosophila kruppel mutants
PLOS Computational Biology, 2012Co-Authors: Konstantin Kozlov, Ekaterina Myasnikova, John Reinitz, Svetlana Surkova, Maria SamsonovaAbstract:The Segmentation Gene network in Drosophila embryo solves the fundamental problem of embryonic patterning: how to establish a periodic pattern of Gene expression, which determines both the positions and the identities of body segments. The gap Gene network constitutes the first zygotic regulatory tier in this process. Here we have applied the systems-level approach to investigate the regulatory effect of gap Gene Kruppel (Kr) on Segmentation Gene expression. We acquired a large dataset on the expression of gap Genes in Kr null mutants and demonstrated that the expression levels of these Genes are significantly reduced in the second half of cycle 14A. To explain this novel biological result we applied the Gene circuit method which extracts regulatory information from spatial Gene expression data. Previous attempts to use this formalism to correctly and quantitatively reproduce gap Gene expression in mutants for a trunk gap Gene failed, therefore here we constructed a revised model and showed that it correctly reproduces the expression patterns of gap Genes in Kr null mutants. We found that the remarkable alteration of gap Gene expression patterns in Kr mutants can be explained by the dynamic decrease of activating effect of Cad on a target Gene and exclusion of Kr Gene from the complex network of gap Gene interactions, that makes it possible for other interactions, in particular, between hb and gt, to come into effect. The successful modeling of the quantitative aspects of gap Gene expression in mutant for the trunk gap Gene Kr is a significant achievement of this work. This result also clearly indicates that the oversimplified representation of transcriptional regulation in the previous models is one of the reasons for unsuccessful attempts of mutant simulations.
-
estimation of errors introduced by confocal imaging into the data on Segmentation Gene expression in drosophila
Bioinformatics, 2009Co-Authors: Ekaterina Myasnikova, Maria Samsonova, Svetlana Surkova, Lena Panok, John ReinitzAbstract:Motivation: Currently the confocal scanning microscopy of fluorescently tagged molecules is extensively employed to acquire quantitative data on Gene expression at cellular resolution. Following this approach, we Generated a large dataset on the expression of Segmentation Genes in the Drosophila blastoderm, that is widely used in systems biology studies. As data accuracy is of critical importance for the success of studies in this field, we took a shot to evaluate possible errors introduced in the data by acquisition and processing methods. This article deals with errors introduced by confocal microscope. Results: In confocal imaging, the inevitable photon noise is commonly reduced by the averaging of multiple frames. The averaging may introduce errors into the data, if single frames are clipped by microscope hardware. A method based on censoring technique is used to estimate and correct this type of errors. Additional source of errors is the quantification of blurred images. To estimate and correct these errors, the Richardson–Lucy deconvolution method was modified to provide the higher accuracy of data read off from blurred images of the Drosophila blastoderm. We have found that the sizes of errors introduced by confocal imaging make up ~5–7% of the mean intensity values and do not disguise the dynamic behavior and characteristic features of Gene expression patterns. We also defined a range of microscope parameters for the acquisition of sufficiently accurate data. Availability: http://urchin.spbcas.ru/downloads/step/step.htm Contact: myasnikova@spbcas.ru Supplementary information:Supplementary data are available at Bioinformatics online.
Maria Samsonova - One of the best experts on this subject based on the ideXlab platform.
-
erratum to quantitative dynamics and increased variability of Segmentation Gene expression in the drosophila kruppel and knirps mutants dev biol 376 2013 99 112
Developmental Biology, 2013Co-Authors: Svetlana Surkova, John Reinitz, E V Golubkova, Lena Panok, Lyudmila Mamon, Maria SamsonovaAbstract:and “Lack of tailless leads to an increase in expression variability in Drosophila embryos” [Dev. Biol. 377 (2013) 305–317] Hilde Janssensa, Anton Crombacha, Karl Richard Wottona, Damjan Cicin-Saina, Svetlana Surkovab, Chea Lu Limc, Maria Samsonovab, Michael Akamc, Johannes Jaegera,c,* aEMBL/CRG Research Unit in Systems Biology, CRG—Centre de Regulacio Genomica, and Universitat Pompeu Fabra (UPF), Dr. Aiguader 88, 08003 Barcelona, Spain bDepartment of Computational Biology, Center for Advanced Studies, St. Petersburg State Polytechnical University, 29 Polytehnicheskaya Street, St. Petersburg 195251, Russia cDepartment of Zoology, Downing Street, Cambridge CB23EJ, UK The articles mentioned above were meant to be published back to back as companion papers in the same issue. *Corresponding authors. E-mail addresses: samson@spbcas.ru (M. Samsonova), yogi.jaeger@crg.eu, yoginho@gmail.com (J. Jaeger).
-
quantitative dynamics and increased variability of Segmentation Gene expression in the drosophila kruppel and knirps mutants
Developmental Biology, 2013Co-Authors: Svetlana Surkova, John Reinitz, E V Golubkova, Lena Panok, Lyudmila Mamon, Maria SamsonovaAbstract:Abstract Here we characterize the response of the Drosophila Segmentation system to mutations in two gap Genes, Kr and kni, in the form of single or double homozygotes and single heterozygotes. Segmentation Gene expression in these genotypes was quantitatively monitored with cellular resolution in space and 6.5 to 13 min resolution in time. As is the case with wild type, we found that Gene expression domains in the posterior portion of the embryo shift to the anterior over time. In certain cases, such as the gt posterior domain in Kr mutants, the shifts are significantly larger than is seen in wild type embryos. We also investigated the effects of Kr and kni on the variability of Gene expression. Mutations often produce variable phenotypes, and it is well known that the cuticular phenotype of Kr mutants is variable. We sought to understand the molecular basis of this effect. We find that throughout cycle 14A the relative levels of eve and ftz expression in stripes 2 and 3 are variable among individual embryos. Moreover, in Kr and kni mutants, unlike wild type, the variability in positioning of the posterior Hb domain and eve stripe 7 is not decreased or filtered with time. The posterior Gt domain in Kr mutants is highly variable at early times, but this variability decreases when this domain shifts in the anterior direction to the position of the neighboring Kni domain. In contrast to these findings, positional variability throughout the embryo does not decrease over time in double Kr;kni mutants. In heterozygotes the early expression patterns of Segmentation Genes resemble patterns seen in homozygous mutants but by the onset of gastrulation they become similar to the wild type patterns. Finally, we note that Gene expression levels are reduced in Kr and kni mutant embryos and have a tendency to decrease over time. This is a surprising result in view of the role that mutual repression is thought to play in the gap Gene system.
-
modeling of gap Gene expression in drosophila kruppel mutants
PLOS Computational Biology, 2012Co-Authors: Konstantin Kozlov, Ekaterina Myasnikova, John Reinitz, Svetlana Surkova, Maria SamsonovaAbstract:The Segmentation Gene network in Drosophila embryo solves the fundamental problem of embryonic patterning: how to establish a periodic pattern of Gene expression, which determines both the positions and the identities of body segments. The gap Gene network constitutes the first zygotic regulatory tier in this process. Here we have applied the systems-level approach to investigate the regulatory effect of gap Gene Kruppel (Kr) on Segmentation Gene expression. We acquired a large dataset on the expression of gap Genes in Kr null mutants and demonstrated that the expression levels of these Genes are significantly reduced in the second half of cycle 14A. To explain this novel biological result we applied the Gene circuit method which extracts regulatory information from spatial Gene expression data. Previous attempts to use this formalism to correctly and quantitatively reproduce gap Gene expression in mutants for a trunk gap Gene failed, therefore here we constructed a revised model and showed that it correctly reproduces the expression patterns of gap Genes in Kr null mutants. We found that the remarkable alteration of gap Gene expression patterns in Kr mutants can be explained by the dynamic decrease of activating effect of Cad on a target Gene and exclusion of Kr Gene from the complex network of gap Gene interactions, that makes it possible for other interactions, in particular, between hb and gt, to come into effect. The successful modeling of the quantitative aspects of gap Gene expression in mutant for the trunk gap Gene Kr is a significant achievement of this work. This result also clearly indicates that the oversimplified representation of transcriptional regulation in the previous models is one of the reasons for unsuccessful attempts of mutant simulations.
-
estimation of errors introduced by confocal imaging into the data on Segmentation Gene expression in drosophila
Bioinformatics, 2009Co-Authors: Ekaterina Myasnikova, Maria Samsonova, Svetlana Surkova, Lena Panok, John ReinitzAbstract:Motivation: Currently the confocal scanning microscopy of fluorescently tagged molecules is extensively employed to acquire quantitative data on Gene expression at cellular resolution. Following this approach, we Generated a large dataset on the expression of Segmentation Genes in the Drosophila blastoderm, that is widely used in systems biology studies. As data accuracy is of critical importance for the success of studies in this field, we took a shot to evaluate possible errors introduced in the data by acquisition and processing methods. This article deals with errors introduced by confocal microscope. Results: In confocal imaging, the inevitable photon noise is commonly reduced by the averaging of multiple frames. The averaging may introduce errors into the data, if single frames are clipped by microscope hardware. A method based on censoring technique is used to estimate and correct this type of errors. Additional source of errors is the quantification of blurred images. To estimate and correct these errors, the Richardson–Lucy deconvolution method was modified to provide the higher accuracy of data read off from blurred images of the Drosophila blastoderm. We have found that the sizes of errors introduced by confocal imaging make up ~5–7% of the mean intensity values and do not disguise the dynamic behavior and characteristic features of Gene expression patterns. We also defined a range of microscope parameters for the acquisition of sufficiently accurate data. Availability: http://urchin.spbcas.ru/downloads/step/step.htm Contact: myasnikova@spbcas.ru Supplementary information:Supplementary data are available at Bioinformatics online.
-
flyex the quantitative atlas on Segmentation Gene expression at cellular resolution
Nucleic Acids Research, 2009Co-Authors: Andrei Pisarev, Maria Samsonova, Ekaterina Poustelnikova, John ReinitzAbstract:The datasets on Gene expression are the valuable source of information about the functional state of an organism. Recently, we have acquired the large dataset on expression of Segmentation Genes in the Drosophila blastoderm. To provide efficient access to the data, we have developed the FlyEx database (http://urchin.spbcas.ru/flyex). FlyEx contains 4716 images of 14 Segmentation Gene expression patterns obtained from 1579 embryos and 9500000 quantitative data records. Reference data are available for all Segmentation Genes in cycles 11–13 and all temporal classes of cycle 14A. FlyEx supports operations on images of Gene expression patterns. The database can be used to examine the quality of data, analyze the dynamics of formation of Segmentation Gene expression domains, as well as to estimate the variability of Gene expression patterns. Currently, a user is able to monitor and analyze the dynamics of formation of Segmentation Gene expression domains over the whole period of segment determination, that amounts to 1.5h of development. FlyEx supports the data downloads and construction of personal reference datasets, that makes it possible to more effectively use and analyze data.
Graham E Budd - One of the best experts on this subject based on the ideXlab platform.
-
deciphering the onychophoran Segmentation Gene cascade Gene expression reveals limited involvement of pair rule Gene orthologs in Segmentation but a highly conserved segment polarity Gene network
Developmental Biology, 2013Co-Authors: Ralf Janssen, Graham E BuddAbstract:The hallmark of the arthropods is their segmented body, although origin of Segmentation, however, is unresolved. In order to shed light on the origin of Segmentation we investigated orthologs of pair rule Genes (PRGs) and segment polarity Genes (SPGs) in a member of the closest related sister-group to the arthropods, the onychophorans. Our Gene expression data analysis suggests that most of the onychophoran PRGs do not play a role in Segmentation. One possible exception is the even-skipped (eve) Gene that is expressed in the posterior end of the onychophoran where new segments are likely patterned, and is also expressed in Segmentation-Gene typical transverse stripes in at least a number of newly formed segments. Other onychophoran PRGs such as runt (run), hairy/Hes (h/Hes) and odd-skipped (odd) do not appear to have a function in Segmentation at all. Onychophoran PRGs that act low in the Segmentation Gene cascade in insects, however, are potentially involved in segment-patterning. Most obvious is that from the expression of the pairberry (pby) Gene ortholog that is expressed in a typical SPG-pattern. Since this result suggested possible conservation of the SPG-network we further investigated SPGs (and associated factors) such as Notum in the onychophoran. We find that the expression patterns of SPGs in arthropods and the onychophoran are highly conserved, suggesting a conserved SPG-network in these two clades, and indeed also in an annelid. This may suggest that the common ancestor of lophotrochozoans and ecdysozoans was already segmented utilising the same SPG-network, or that the SPG-network was recruited independently in annelids and onychophorans/arthropods.
-
expression of pair rule Gene orthologs in the blastoderm of a myriapod evidence for pair rule like mechanisms
BMC Developmental Biology, 2012Co-Authors: Ralf Janssen, Wim G.m. Damen, Graham E BuddAbstract:Background A hallmark of Drosophila Segmentation is the stepwise subdivision of the body into smaller and smaller units, and finally into the segments. This is achieved by the function of the well-understood Segmentation Gene cascade. The first molecular sign of a segmented body appears with the action of the pair rule Genes, which are expressed as transversal stripes in alternating segments. Drosophila development, however, is derived, and in most other arthropods only the anterior body is patterned (almost) simultaneously from a pre-existing field of cells; posterior segments are added sequentially from a posterior segment addition zone. A long-standing question is to what extent Segmentation mechanisms known from Drosophila may be conserved in short-germ arthropods. Despite the derived developmental modes, it appears more likely that conserved mechanisms can be found in anterior patterning.
Berta Verd - One of the best experts on this subject based on the ideXlab platform.
-
a damped oscillator imposes temporal order on posterior gap Gene expression in drosophila
PLOS Biology, 2018Co-Authors: Hilde Janssens, Karl R Wotton, Eva Jimenezguri, Berta Verd, Erik ClarkAbstract:Insects determine their body segments in two different ways. Short-germband insects, such as the flour beetle Tribolium castaneum, use a molecular clock to establish segments sequentially. In contrast, long-germband insects, such as the vinegar fly Drosophila melanogaster, determine all segments simultaneously through a hierarchical cascade of Gene regulation. Gap Genes constitute the first layer of the Drosophila Segmentation Gene hierarchy, downstream of maternal gradients such as that of Caudal (Cad). We use data-driven mathematical modelling and phase space analysis to show that shifting gap domains in the posterior half of the Drosophila embryo are an emergent property of a robust damped oscillator mechanism, suggesting that the regulatory dynamics underlying long- and short-germband Segmentation are much more similar than previously thought. In Tribolium, Cad has been proposed to modulate the frequency of the Segmentation oscillator. Surprisingly, our simulations and experiments show that the shift rate of posterior gap domains is independent of maternal Cad levels in Drosophila. Our results suggest a novel evolutionary scenario for the short- to long-germband transition and help explain why this transition occurred convergently multiple times during the radiation of the holometabolan insects.
-
a damped oscillator imposes temporal order on posterior gap Gene expression in drosophila
bioRxiv, 2017Co-Authors: Hilde Janssens, Anton Crombach, Karl R Wotton, Eva Jimenezguri, Berta Verd, Erik Clark, Johannes JaegerAbstract:Insects determine their body segments in two different ways. Short-germband insects, such as the flour beetle Tribolium castaneum, use a molecular clock to establish segments sequentially. In contrast, long-germband insects, such as the vinegar fly Drosophila melanogaster, determine all segments simultaneously through a hierarchical cascade of Gene regulation. Gap Genes constitute the first layer of the Drosophila Segmentation Gene hierarchy, downstream of maternal gradients. We use data driven modelling and phase space analysis to show that shifting gap domains in the posterior half of the Drosophila embryo are an emergent property of a robust damped oscillator mechanism. The rate at which gap domains shift is determined by the level of maternal Caudal (Cad), which also regulates the frequency of the Tribolium molecular clock. Our evidence indicates that the regulatory dynamics underlying long- and short-germband Segmentation are much more similar than previously thought. This similarity may help explain why long-germband Segmentation evolved convergently multiple times during the radiation of the holometabolan insects.