scholarly journals Spatial expression of Hox cluster genes in the ontogeny of a sea urchin

Development ◽  
2000 ◽  
Vol 127 (21) ◽  
pp. 4631-4643 ◽  
Author(s):  
C. Arenas-Mena ◽  
A.R. Cameron ◽  
E.H. Davidson
Keyword(s):  
Sea Urchin ◽  
Larval Stage ◽  
Hox Genes ◽  
Expression Patterns ◽  
Evolutionary Process ◽  
Body Plan ◽  
Hox Cluster ◽  
Spatial Expression ◽  
Neural Tissues ◽  
Adult Body

The Hox cluster of the sea urchin Strongylocentrous purpuratus contains ten genes in a 500 kb span of the genome. Only two of these genes are expressed during embryogenesis, while all of eight genes tested are expressed during development of the adult body plan in the larval stage. We report the spatial expression during larval development of the five ‘posterior’ genes of the cluster: SpHox7, SpHox8, SpHox9/10, SpHox11/13a and SpHox11/13b. The five genes exhibit a dynamic, largely mesodermal program of expression. Only SpHox7 displays extensive expression within the pentameral rudiment itself. A spatially sequential and colinear arrangement of expression domains is found in the somatocoels, the paired posterior mesodermal structures that will become the adult perivisceral coeloms. No such sequential expression pattern is observed in endodermal, epidermal or neural tissues of either the larva or the presumptive juvenile sea urchin. The spatial expression patterns of the Hox genes illuminate the evolutionary process by which the pentameral echinoderm body plan emerged from a bilateral ancestor.

scholarly journals Hex Hox: De Novo Transcriptome Assembly and Embryonic Hox Gene Expression in the Burrowing Mayfly Hexagenia Limbata (Ephemeridae)

2021 ◽  
Author(s):  
Christopher J Gonzalez ◽  
Tobias R Hildebrandt ◽  
Brigid C O'Donnell
Keyword(s):  
Hox Genes ◽  
Transcriptome Assembly ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Body Plan ◽  
The Body ◽  
Phylogenetic Position ◽  
Developmental Genetics ◽  
Early Instar ◽  
Hexagenia Limbata

Abstract Background: Hox genes are key regulators of appendage development in the insect body plan. The body plan of Mayfly (Ephemeroptera) nymphs differs due to the presence of evolutionarily significant abdominal appendages called gills. Despite mayflies’ basal phylogenetic position and novel morphology amongst insects, little is known of their developmental genetics. Here we present an annotated transcriptome for the mayfly Hexagenia limbata, with annotated sequences for putative Hox peptides and embryonic expression profiles for the Hox genes Antp and Ubx/abd-A. Results: Transcriptomic sequencing of early instar H. limbata nymphs yielded a high-quality assembly of 83,795 contigs, of which 22,975 were annotated against Folsomia candida, Nilaparvata lugens, Zootermopsis nevadensis and UniRef90 protein databases. Peptide annotations included eight of the ten canonical Hox genes (lab, pb, Dfd, Scr, Antp, Ubx, abd-A and Abd-B), most of which contained all functional domains and motifs conserved in insects. Expression patterns of Antp and Ubx/abd-A in H. limbata were visualized from early to late embryogenesis, and are also highly conserved with patterns reported for other non-holometabolous insects.Conclusions: We present evidence that both H. limbata Hox peptide sequences and embryonic expression patterns for Antp and Ubx/abd-A are extensively conserved with other insects. These findings suggest mayfly Antp and Ubx/abd-A play similar appendage promoting and repressing roles in the thorax and abdomen, respectively. The identified expression of Ubx and abd-A in early instar nymphs further suggests that mayfly gill development is not subject to Ubx or abd-A repression. Previous studies have shown that insect Ubx and abd-A repress appendages by inhibiting their distal structures, which can permit the development of proximal appendage types. In line with past morphology-based work, we propose that mayfly gills are proximal appendage structures, possibly homologous to the proximal appendage structures of crustaceans.

Exploring the myriapod body plan: expression patterns of the ten Hox genes in a centipede

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1225-1238 ◽  
Author(s):  
Cynthia L. Hughes ◽  
Thomas C. Kaufman
Keyword(s):  
Gene Expression ◽  
Hox Genes ◽  
Expression Patterns ◽  
Body Plan ◽  
Phylogenetic Position ◽  
The Novel ◽  
Fushi Tarazu ◽  
Hox Gene ◽  
Insight Into ◽  
Gaining Insight

The diversity of the arthropod body plan has long been a fascinating subject of study. A flurry of recent research has analyzed Hox gene expression in various arthropod groups, with hopes of gaining insight into the mechanisms that underlie their evolution. The Hox genes have been analyzed in insects, crustaceans and chelicerates. However, the expression patterns of the Hox genes have not yet been comprehensively analyzed in a myriapod. We present the expression patterns of the ten Hox genes in a centipede, Lithobius atkinsoni, and compare our results to those from studies in other arthropods. We have three major findings. First, we find that Hox gene expression is remarkably dynamic across the arthropods. The expression patterns of the Hox genes in the centipede are in many cases intermediate between those of the chelicerates and those of the insects and crustaceans, consistent with the proposed intermediate phylogenetic position of the Myriapoda. Second, we found two ‘extra’ Hox genes in the centipede compared with those in Drosophila. Based on its pattern of expression, Hox3 appears to have a typical Hox-like role in the centipede, suggesting that the novel functions of the Hox3 homologs zen and bicoid were adopted somewhere in the crustacean-insect clade. In the centipede, the expression of the gene fushi tarazu suggests that it has both a Hox-like role (as in the mite), as well as a role in segmentation (as in insects). This suggests that this dramatic change in function was achieved via a multifunctional intermediate, a condition maintained in the centipede. Last, we found that Hox expression correlates with tagmatic boundaries, consistent with the theory that changes in Hox genes had a major role in evolution of the arthropod body plan.

Zebrafish wnt8 and wnt8b share a common activity but are involved in distinct developmental pathways

Development ◽  
1995 ◽  
Vol 121 (6) ◽  
pp. 1787-1799 ◽  
Author(s):  
G.M. Kelly ◽  
P. Greenstein ◽  
D.F. Erezyilmaz ◽  
R.T. Moon
Keyword(s):  
Expression Patterns ◽  
Body Plan ◽  
Developmental Pathways ◽  
Rt Pcr ◽  
Tail Bud ◽  
Pcr Assay ◽  
Dorsal Midline ◽  
Spatial Expression ◽  
Common Activity ◽  
Marginal Cells

The specification of the vertebrate body plan is dependent on numerous signaling molecules, including members of the Wnt family. We have identified two zebrafish wnt8 paralogs related to Xwnt-8B and Xwnt-8, respectively. A RT-PCR assay demonstrated that wnt8 is expressed maternally, with transcripts detected throughout embryogenesis, whereas wnt8b transcripts were first detected during late gastrulation. The wnt8 transcripts at 50% epiboly are spatially restricted to those cells at the blastoderm margin, overlying gsc-expressing cells in the axial hypoblast. During late gastrulation, wnt8 was no longer detected in the marginal cells at the dorsal midline and by mid-segmentation, transcripts were found in the presumptive tail bud. In contrast, wnt8b expression is spatially restricted to prospective neuroepithelium, and later to neural-specific structures. Overexpression of both wnts results in two major phenotypes: radialized embryos and embryos with anterior defects. These phenotypes were preceded by significant changes in the spatial expression patterns of gsc and ntl transcripts, reminiscent of activities of Xwnt-8 in Xenopus, and consistent with a role for wnt8 in the specification or patterning of mesoderm.

scholarly journals Hox genes and evolution

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 859 ◽  
Author(s):  
Steven M. Hrycaj ◽  
Deneen M. Wellik
Keyword(s):  
Hox Genes ◽  
Expression Patterns ◽  
Critical Role ◽  
Body Plan ◽  
Functional Conservation ◽  
Fresh Perspective ◽  
Numerous Data ◽  
Segmental Identity ◽  
Putative Mechanism

Hox proteins are a deeply conserved group of transcription factors originally defined for their critical roles in governing segmental identity along the antero-posterior (AP) axis in Drosophila. Over the last 30 years, numerous data generated in evolutionarily diverse taxa have clearly shown that changes in the expression patterns of these genes are closely associated with the regionalization of the AP axis, suggesting that Hox genes have played a critical role in the evolution of novel body plans within Bilateria. Despite this deep functional conservation and the importance of these genes in AP patterning, key questions remain regarding many aspects of Hox biology. In this commentary, we highlight recent reports that have provided novel insight into the origins of the mammalian Hox cluster, the role of Hox genes in the generation of a limbless body plan, and a novel putative mechanism in which Hox genes may encode specificity along the AP axis. Although the data discussed here offer a fresh perspective, it is clear that there is still much to learn about Hox biology and the roles it has played in the evolution of the Bilaterian body plan.

Zebrafish hox genes: genomic organization and modified colinear expression patterns in the trunk

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 407-420 ◽  
Author(s):  
V.E. Prince ◽  
L. Joly ◽  
M. Ekker ◽  
R.K. Ho
Keyword(s):  
Hox Genes ◽  
Genomic Organization ◽  
Expression Patterns ◽  
Regional Identity ◽  
Hoxa Cluster ◽  
Hox Cluster ◽  
Sequence Homologies ◽  
Race Pcr ◽  
Linkage Relationships ◽  
Hox Clusters

The Hox genes are implicated in conferring regional identity to the anteroposterior axis of the developing embryo. We have characterized the organization and expression of hox genes in the teleost zebrafish (Danio rerio), and compared our findings with those made for the tetrapod vertebrates. We have isolated 32 zebrafish hox genes, primarily via 3′RACE-PCR, and analyzed their linkage relationships using somatic cell hybrids. We find that in comparison to the tetrapods, zebrafish has several additional hox genes, both within and beyond the expected 4 hox clusters (A-D). For example, we have isolated a member of hox paralogue group 8 lying on the hoxa cluster, and a member of hox paralogue group 10 lying on the b cluster, no equivalent genes have been reported for mouse or human. Beyond the 4 clusters (A-D) we have isolated a further 3 hox genes (the hoxx and y genes), which according to their sequence homologies lie in paralogue groups 4, 6, and 9. The hoxx4 and hoxx9 genes occur on the same set of hybrid chromosomes, hinting at the possibility of an additional hox cluster for the zebrafish. Similar to their tetrapod counterparts, zebrafish hox genes (including those with no direct tetrapod equivalent) demonstrate colinear expression along the anteroposterior (AP) axis of the embryo. However, in comparison to the tetrapods, anterior hox expression limits are compacted over a short AP region; some members of adjacent paralogue groups have equivalent limits. It has been proposed that during vertebrate evolution, the anterior limits of Hox gene expression have become dispersed along the AP axis allowing the genes to take on novel patterning roles and thus leading to increased axial complexity. In the teleost zebrafish, axial organization is relatively simple in comparison to that of the tetrapod vertebrates; this may be reflected by the less dispersed expression domains of the zebrafish hox genes.

scholarly journals The Hox genes of the direct-type developing sea urchin Peronella japonica

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S73-S73
Author(s):  
Shoutaro Yamaguchi ◽  
Yuko Hano ◽  
Akane Hayashi ◽  
Masaaki Yamaguchi
Keyword(s):  
Gene Expression ◽  
Gene Cluster ◽  
Sea Urchin ◽  
Hox Genes ◽  
Expression Patterns ◽  
Spatial Patterning ◽  
Rt Pcr ◽  
Good System ◽  
Adult Rudiment ◽  
Anterior Posterior

The Hox gene cluster controls spatial patterning mechanisms along the anterior/posterior axis of bilateral metazoans. There exists a co-linearity between the order of the Hox genes in the genome and the spatial order of their domains of expression during development. Echinoderms have pentamerous radial body plans that are different from those of other deuterostomes. Thus expression patterns of echinoderm Hox genes in the adult rudiment might illuminate their evolutionary transformations from bilateral to radial structures. Since Peronella japonica is a direct-type developer that metamorphoses in 3 days without feeding, it provides a good system in which to analyse Hox gene expression in the rudiment.We PCR-amplified the Hox-type sequences of P. japonica using genome DNA and cDNA prepared from larval RNAs as a template. We used two pairs of degenerated primers that corresponded to the first and third helices of the homeodomain of the Hox genes. As a result we obtained 13 Hox-type sequences, named Pj1–Pj13 in order of their determination. All the sequences were detected by RT-PCR, suggesting that they are being expressed in larvae (Table 1).

scholarly journals The unusual gene order in the Echinoderm Hox cluster is related to the embryo and larva symmetries

2015 ◽  
Author(s):  
Spyros Papageorgiou
Keyword(s):  
Sea Urchin ◽  
Gene Sequence ◽  
Hox Genes ◽  
Developmental Stages ◽  
Rotational Symmetry ◽  
The Body ◽  
Gene Location ◽  
Linear Arrangement ◽  
Hox Gene ◽  
Hox Cluster

Background: Hox gene collinearity relates the sequential location of Hox genes in the 3´ to 5´ direction on the chromosome with the linear arrangement of the body elements along the anterior-posterior (A/P) axis of bilaterian embryos. This spatial Hox gene collinearity has been almost universally respected in diverse organisms like worms, insects or vertebrates. It is therefore surprising that the above well established collinearity rule is violated in the case of Echinoderms. No explanation of this violation is apparent. Here a hypothesis is put forward which provides a cue to understand the abnormal serial gene location in the sea urchin disorganized Hox cluster. Results: Bilateral symmetry along the A/P embryo axis is established at the very early stages of ontogeny of the sea urchin. For the subsequent developmental stages, rotational symmetry emerges in the vestibula larva. In analogy to the linear A/P case, the circular topology of modules might be a reflection of the architectural restructuring of the Hox loci where the 3´ and 5´ ends of the Hox cluster approach each other so that a closed contour of the chromatin fiber is formed. At a later stage, the break and opening of the cluster contour at the level of Hox4 combined with the rotational symmetry leads to the observed Hox gene sequence that violates the standard 3´ to 5´ collinearity. Conclusion: The unusual gene series manifests the congruence of Hox gene sequence in the cluster with the circular arrangement of the sea urchin primary podia. Accordingly, the Hox sequence after the break at Hox4 is not a violation but an extension of Hox gene collinearity to animals with rotational symmetry.

scholarly journals Sea urchin Hox genes: insights into the ancestral Hox cluster

1996 ◽  
Vol 13 (8) ◽  
pp. 1078-1086 ◽  
Author(s):  
E. Popodi ◽  
J. C. Kissinger ◽  
M. E. Andrews ◽  
R. A. Raff
Keyword(s):  
Sea Urchin ◽  
Hox Genes ◽  
Hox Cluster

scholarly journals Spatial expression patterns of delta, gcm and brachyury in the cidaroid sea urchin Eucidaris tribuloides

2011 ◽  
Vol 356 (1) ◽  
pp. 252
Author(s):  
Hyla Sweet ◽  
Deepika Sharma ◽  
Rae Ann Covington ◽  
Alicia Wooten ◽  
John Bednarz
Keyword(s):  
Sea Urchin ◽  
Expression Patterns ◽  
Spatial Expression
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