Homologs of wingless and decapentaplegic display a complex and dynamic expression profile during appendage development in the millipede Glomeris marginata (Myriapoda: Diplopoda)

BACKGROUND: The Drosophila genes wingless (wg) and decapentaplegic (dpp) comprise the top level of a hierarchical gene cascade involved in proximal-distal (PD) patterning of the legs. It remains unclear, whether this cascade is common to the appendages of all arthropods. Here, wg and dpp are studied in the millipede Glomeris marginata, a representative of the Myriapoda. RESULTS: Glomeris wg (Gm-wg) is expressed along the ventral side of the appendages compatible with functioning during the patterning of both the PD and dorsal-ventral (DV) axes. Gm-wg may also be involved in sensory organ formation in the gnathal appendages by inducing the expression of Distal-less (Dll) and H15 in the organ primordia. Expression of Glomeris dpp (Gm-dpp) is found at the tip of the trunk legs as well as weakly along the dorsal side of the legs in early stages. Taking data from other arthropods into account, these results may be interpreted in favor of a conserved mode of WG/DPP signaling. Apart from the main PD axis, many arthropod appendages have additional branches (e.g. endites). It is debated whether these extra branches develop their PD axis via the same mechanism as the main PD axis, or whether branch-specific mechanisms exist. Gene expression in possible endite homologs in Glomeris argues for the latter alternative. CONCLUSION: All available data argue in favor of a conserved role of WG/DPP morphogen gradients in guiding the development of the main PD axis. Additional branches in multibranched (multiramous) appendage types apparently do not utilize the WG/DPP signaling system for their PD development. This further supports recent work on crustaceans and insects, that lead to similar conclusions

Parasegmental appendage allocation in annelids and arthropods and the homology of parapodia and arthropodia

The new animal phylogeny disrupts the traditional taxon Articulata (uniting arthropods and annelids) and thus calls into question the homology of the body segments and appendages in the two groups. Recent work in the annelid Platynereis dumerilii has shown that although the set of genes involved in body segmentation is similar in the two groups, the body units of annelids correspond to arthropod parasegments not segments. This challenges traditional ideas about the homology of "segmental" organs in annelids and arthropods, including their appendages. Here I use the expression of engrailed, wingless and Distal-less in the arthropod Artemia franciscana to identify the parasegment boundary and the appendage primordia. I show that the early body organization including the appendage primordia is parasegmental and thus identical to the annelid organization and by deriving the different adult appendages from a common ground plan I suggest that annelid and arthropod appendages are homologous structures despite their different positions in the adult animals. This also has implications for the new animal phylogeny, because it suggests that Urprotostomia was not only parasegmented but also had parasegmental appendages similar to extant annelids, and that limb-less forms in the Protostomia are derived from limb-bearing forms

Vergleichende Studien zur Gliedmaßenentwicklung bei Arthropoden

Die Gliedmaßen der Arthropoden (die Arthropodien) sind seit jeher ein wichtiger Merkmalskomplex für die phylogenetische Forschung. Ziel dieser Arbeit war es, die molekularen Mechanismen der Beinentwicklung in mehreren Arthropodenarten vergleichend zu untersuchen. Auf diese Weise sollten konservierte und divergente Aspekte der Beinentwicklung beleuchtet werden und nach Anhaltspunkten gesucht werden, die Aufschlüsse über die Stammesgeschichte der Arthropoden geben können. In Drosophila existiert eine hierarchische, dreischichtige Genkaskade, welche das Beinwachstum und die Beinsegmentierung steuert. Homologe Gene zu allen drei Ebenen dieser Genkaskade wurden aus dem Tausendfüßer Glomeris marginata und der Kammspinne Cupiennius salei isoliert und untersucht; ergänzende Studien wurden auch mit dem Mehlkäfer Tribolium castaneum, der Taufliege Drosophila melanogaster und der Hausspinne Tegenaria atrica durchgeführt. Es zeigte sich, daß bezüglich aller Genexpressionen Unterschiede zwischen den Arten existieren. Allerdings sprechen die vorliegenden Daten trotzdem für eine Konservierung der Genkaskade innerhalb der Arthropoden. Die Feinjustierung innerhalb der Genkaskade ist aber offensichtlich in den unterschiedlichen Arthropodengruppen jeweils anders geregelt. Auf Grund dieser Tatsache wird dem Gedanken eine Absage erteilt, daß die Beinsegmente verschiedener Beintypen und Arthropodenklassen miteinander direkt oder seriell homologisiert werden können. Daneben wurde die Morphogenese der Beine von Cupiennius näher untersucht. Es zeigte sich, daß in der Nähe der entstehenden Gelenke Wachstumszonen existieren, deren Aktivität offenbar durch den Notch- und den Egfr-Signalweg, zwei wichtige Signalwege, gesteuert wird. Obwohl zu den Wachstumszonen bislang nur wenig vergleichende Daten vorliegen, deutet manches darauf hin, daß auch diese morphogenetischen Zentren innerhalb der Arthropoden konserviert sind. Auf der Basis der gewonnenen Daten wird schließlich gezeigt, wie damit neue Homologie- und Stammbaumhypothesen postuliert werden können. Dies zeigt zugleich wie lückenhaft unser Wissen über die Evolution der Gliedmaßen bei Arthropoden noch immer ist. Der Ursprung der Arthropodien und die Beschaffenheit des Urarthropodiums bleiben auch weiterhin offene Fragen der Phylogenetik

A review of the correlation of tergites, sternites, and leg pairs in diplopods

In some arthropods there is a discrepancy in the number of dorsal tergites compared to the number of ventral sternites and leg pairs. The posterior tergites of the Diplopoda (millipedes) each cover two sternites and two pairs of legs. This segment arrangement is called diplosegmentation. The molecular nature of diplosegmentation is still unknown. There are even conflicting theories on the way the tergites and sternites/leg pairs should be correlated to each other. The different theories are based either on embryological analyses or on studies of the adult morphology and turned out to be not compatible with each other. We have previously used the expression patterns of segmentation genes in the pill millipede Glomeris marginata (Myriapoda: Diplopoda) to study millipede segmentation. Here we review the existing models on the alignment of tergites and leg pairs in millipedes with special emphasis on the implications the gene expression data have on the debate of tergite and leg pair assignment in millipedes. The remarkable outcome of the gene expression analysis was that (1) there is no coupling of dorsal and ventral segmentation and, importantly, that (2) the boundaries delimiting the tergites do neither correlate to the embryonic boundaries of the dorsal embryonic segments nor to the boundaries of the ventral embryonic segments. Using these new insights, we critically reinvestigated the correlation of tergites, sternites, and leg pairs in millipedes. Our model, which takes into account that the tergite boundaries are different from the dorsal embryonic segment boundaries, provides a solution of the problem of tergite to sternite/leg pair correlation in basal milipedes with non-fused exoskeletal elements and also has implications for derived species with exoskeletal rings. Moreover, lack of coupling of dorsal and ventral segmentation may also explain the discrepancy in numbers of dorsal tergites and ventral leg pairs seen in some other arthropods

Публікації ХVІІІ - поч. ХХІ ст. про центральноукраїнські археологічні пам’ятки в Ермітажі

(UA) 1764 р. вийшла публікація Г. Міллера про наслідки перших археологічних розкопок в Україні. Виявлений тоді Литий скарб потрапив до Кунсткамери, а потім – до Ермітажу. Наступні автори вивчали, характеризували цю колекцію, виходячи з отриманих нових даних скіфологією. З ’являлася у світ інформація й про інші надходження до Ермітажу з території, яка сьогодні входить до Кіровоградщини. Ці публікації можуть стати певними свідченнями для обґрунтування постановки питання повернення історичних художніх цінностей з-за кордону до музейного фонду України.(EN) In 1764 the publication of G. Muller went out about the consequences of the first archaeological excavations in Ukraine. Poured treasure is educed then got to Cabinet of curiosities, and then to the Hermitage. Next authors studied, characterized this collection, coming from the obtained new data, as scythology. Information was published about other receivabless to the Hermitage from territory that is today included to the Kirovohrad area. These publications can become certain certificates for the ground of statement of a question of return of historical artistic values in the museum fund of Ukraine

A clustered set of three Sp-family genes is ancestral in the Metazoa: evidence from sequence analysis, protein domain structure, developmental expression patterns and chromosomal location

<p>Abstract</p> <p>Background</p> <p>The Sp-family of transcription factors are evolutionarily conserved zinc finger proteins present in many animal species. The orthology of the Sp genes in different animals is unclear and their evolutionary history is therefore controversially discussed. This is especially the case for the Sp gene <it>buttonhead </it>(<it>btd</it>) which plays a key role in head development in <it>Drosophila melanogaster</it>, and has been proposed to have originated by a recent gene duplication. The purpose of the presented study was to trace orthologs of <it>btd </it>in other insects and reconstruct the evolutionary history of the Sp genes within the metazoa.</p> <p>Results</p> <p>We isolated Sp genes from representatives of a holometabolous insect (<it>Tribolium castaneum</it>), a hemimetabolous insect (<it>Oncopeltus fasciatus</it>), primitively wingless hexapods (<it>Folsomia candida </it>and <it>Thermobia domestica</it>), and an amphipod crustacean (<it>Parhyale hawaienis</it>). We supplemented this data set with data from fully sequenced animal genomes. We performed phylogenetic sequence analysis with the result that all Sp factors fall into three monophyletic clades. These clades are also supported by protein domain structure, gene expression, and chromosomal location. We show that clear orthologs of the <it>D. melanogaster btd </it>gene are present even in the basal insects, and that the <it>Sp5</it>-related genes in the genome sequence of several deuterostomes and the basal metazoans <it>Trichoplax adhaerens </it>and <it>Nematostella vectensis </it>are also orthologs of <it>btd</it>.</p> <p>Conclusions</p> <p>All available data provide strong evidence for an ancestral cluster of three Sp-family genes as well as synteny of this Sp cluster and the Hox cluster. The ancestral Sp gene cluster already contained a <it>Sp5/btd </it>ortholog, which strongly suggests that <it>btd </it>is not the result of a recent gene duplication, but directly traces back to an ancestral gene already present in the metazoan ancestor.</p

Expression of myriapod pair rule gene orthologs

Background Segmentation is a hallmark of the arthropods; most knowledge about the molecular basis of arthropod segmentation comes from work on the fly Drosophila melanogaster. In this species a hierarchic cascade of segmentation genes subdivides the blastoderm stepwise into single segment wide regions. However, segmentation in the fly is a derived feature since all segments form virtually simultaneously. Conversely, in the vast majority of arthropods the posterior segments form one at a time from a posterior pre-segmental zone. The pair rule genes (PRGs) comprise an important level of the Drosophila segmentation gene cascade and are indeed the first genes that are expressed in typical transverse stripes in the early embryo. Information on expression and function of PRGs outside the insects, however, is scarce. Results Here we present the expression of the pair rule gene orthologs in the pill millipede Glomeris marginata (Myriapoda: Diplopoda). We find evidence that these genes are involved in segmentation and that components of the hierarchic interaction of the gene network as found in insects may be conserved. We further provide evidence that segments are formed in a single-segment periodicity rather than in pairs of two like in another myriapod, the centipede Strigamia maritima. Finally we show that decoupling of dorsal and ventral segmentation in Glomeris appears already at the level of the PRGs. Conclusions Although the pair rule gene network is partially conserved among insects and myriapods, some aspects of PRG interaction are, as suggested by expression pattern analysis, convergent, even within the Myriapoda. Conserved expression patterns of PRGs in insects and myriapods, however, may represent ancestral features involved in segmenting the arthropod ancestor

Expression of homothorax and extradenticle mRNA in the legs of the crustacean Parhyale hawaiensis: evidence for a reversal of gene expression regulation in the pancrustacean lineage

In Drosophila leg development, the extradenticle (exd) gene is expressed ubiquitously and its co-factor homothorax (hth) is restricted to the proximal leg portion. This condition is conserved in other insect species but is reversed in chelicerates and myriapods. As the region of co-expression does not differ in the two groups and transcripts from both are necessary for function, this difference in expression is likely to be functionally neutral. Here, we report the expression patterns of exd and hth in a crustacean, the amphipod shrimp Parhyale hawaiensis. The patterns in P. hawaiensis are similar to the insect patterns, supporting the close relationship between crustaceans and insects in the taxon Tetraconata. However, mRNA expression of exd in P. hawaiensis is weak in the distal leg parts, thus being intermediate between the complete lack of distal exd expression in chelicerates and myriapods and the strong distal exd expression in insects. Our data suggest that the reversal of the gene expression regulation of hth and exd occurred in the pancrustacean lineage

A conserved function of the zinc finger transcription factor Sp8/9 in allometric appendage growth in the milkweed bug Oncopeltus fasciatus

The genes encoding the closely related zinc finger transcription factors Buttonhead (Btd) and D-Sp1 are expressed in the developing limb primordia of Drosophila melanogaster and are required for normal growth of the legs. The D-Sp1 homolog of the red flour beetle Tribolium castaneum, Sp8 (appropriately termed Sp8/9), is also required for the proper growth of the leg segments. Here we report on the isolation and functional study of the Sp8/9 gene from the milkweed bug Oncopeltus fasciatus. We show that Sp8/9 is expressed in the developing appendages throughout development and that the downregulation of Sp8/9 via RNAi leads to antennae, rostrum, and legs with shortened and fused segments. This supports a conserved role of Sp8/9 in allometric leg segment growth. However, all leg segments including the claws are present and the expression of the leg genes Distal-less, dachshund, and homothorax are proportionally normal, thus providing no evidence for a role of Sp8/9 in appendage specification

Separable functions of wingless in distal and ventral patterning of the Tribolium leg

The gene wingless (wg) in Drosophila is an important factor in leg development. During embryonic development wg is involved in the allocation of the limb primordia. During imaginal disk development wg is involved in distal development and it has a separate role in ventral development. The expression pattern of wg is highly conserved in all arthropods (comprising data from insects, myriapods, crustaceans, and chelicerates), suggesting that its function in leg development is also conserved. However, recent work in other insects (e.g. the milkweed bug Oncopeltus fasciatus) argued against a role of wg in leg development. We have studied the role of wg in leg development of the flour beetle Tribolium castaneum. Using stage-specific staggered embryonic RNAi in wild-type and transgenic EGFP expressing enhancer trap lines we are able to demonstrate separable functions of Tribolium wg in distal and in ventral leg development. The distal role affects all podomeres distal to the coxa, whereas the ventral role is restricted to cells along the ventral midline of the legs. In addition, severe leg defects after injection into early embryonic stages are evidence that wg is also involved in proximal development and limb allocation in Tribolium. Our data suggest that the roles of wg in leg development are highly conserved in the holometabolous insects. Further studies will reveal the degree of conservation in other arthropod groups