Spatially restricted expression of PlOtp, a Paracentrotus lividus orthopedia-related homeobox gene, is correlated with oral ectodermal patterning and skeletal morphogenesis in late-cleavage sea urchin embryos

Several homeobox genes are expressed in the sea urchin embryo but their roles in development have yet to be elucidated. Of particular interest are homologues of homeobox genes that in mouse and Drosophila are involved in patterning the developing central nervous system (CNS). Here, we report the cloning of an orthopedia (Otp)-related gene from Paracentrotus lividus, PlOtp. Otp is a single copy zygotic gene that presents a unique and highly restricted expression pattern. Transcripts were first detected at the mid-gastrula stage in two pairs of oral ectoderm cells located in a ventrolateral position, overlying primary mesenchyme cell (PMC) clusters. Increases in both transcript abundance and the number of Otp-expressing cells were observed at prism and pluteus stages. Otp transcripts are symmetrically distributed in a few ectodermal cells of the oral field. Labelled cells were observed close to sites of active skeletal rod growth (tips of the budding oral and anal arms), and at the juxtaposition of stomodeum and foregut. Chemicals known to perturb PMC patterning along animal-vegetal and oral-aboral axes altered the pattern of Otp expression. Vegetalization by LiCl caused a shift in Otp-expressing cells toward the animal pole, adjacent to shifted PMC aggregates. Nickel treatment induced expression of the Otp gene in an increased number of ectodermal cells, which adopted a radialized pattern. Finally, ectopic expression of Otp mRNA affected patterning along the oral-aboral axis and caused skeletal abnormalities that resembled those exhibited by nickel-treated embryos. From these results, we conclude that the Otp homeodomain gene is involved in short-range cell signalling within the oral ectoderm for patterning the endoskeleton of the larva through epithelial-mesenchymal interactions.

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Requirements of Lim1, a Drosophila LIM-homeobox gene, for normal leg and antennal development

Development ◽

10.1242/dev.127.20.4315 ◽

2000 ◽

Vol 127 (20) ◽

pp. 4315-4323 ◽

Cited By ~ 3

Author(s):

T. Tsuji ◽

A. Sato ◽

I. Hiratani ◽

M. Taira ◽

K. Saigo ◽

...

Keyword(s):

Ectopic Expression ◽

Homeobox Genes ◽

Homeobox Gene ◽

Homeodomain Protein ◽

Border Cells ◽

Null Mutant ◽

Tarsal Segment ◽

Segment Boundary ◽

Leg Development ◽

Antagonistic Interactions

During Drosophila leg development, the distal-most compartment (pretarsus) and its immediate neighbour (tarsal segment 5) are specified by a pretarsus-specific homeobox gene, aristaless, and tarsal-segment-specific Bar homeobox genes, respectively; the pretarsus/tarsal-segment boundary is formed by antagonistic interactions between Bar and pretarsus-specific genes that include aristaless (Kojima, T., Sato, M. and Saigo, K. (2000) Development 127, 769–778). Here, we show that Drosophila Lim1, a homologue of vertebrate Lim1 encoding a LIM-homeodomain protein, is involved in pretarsus specification and boundary formation through its activation of aristaless. Ectopic expression of Lim1 caused aristaless misexpression, while aristaless expression was significantly reduced in Lim1-null mutant clones. Pretarsus Lim1 expression was negatively regulated by Bar and abolished in leg discs lacking aristaless activity, which was associated with strong Bar misexpression in the presumptive pretarsus. No Lim1 misexpression occurred upon aristaless misexpression. The concerted function of Lim1 and aristaless was required to maintain Fasciclin 2 expression in border cells and form a smooth pretarsus/tarsal-segment boundary. Lim1 was also required for femur, coxa and antennal development.

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Early asymmetric cues triggering the dorsal/ventral gene regulatory network of the sea urchin embryo

eLife ◽

10.7554/elife.04664 ◽

2014 ◽

Vol 3 ◽

Cited By ~ 22

Author(s):

Vincenzo Cavalieri ◽

Giovanni Spinelli

Keyword(s):

Gene Regulatory Network ◽

Sea Urchin ◽

Regulatory Network ◽

Ectopic Expression ◽

Paracentrotus Lividus ◽

Loss Of Function ◽

Mapk Activity ◽

Sea Urchin Embryo ◽

Gene Regulatory ◽

Dorsal Cells

Dorsal/ventral (DV) patterning of the sea urchin embryo relies on a ventrally-localized organizer expressing Nodal, a pivotal regulator of the DV gene regulatory network. However, the inceptive mechanisms imposing the symmetry-breaking are incompletely understood. In Paracentrotus lividus, the Hbox12 homeodomain-containing repressor is expressed by prospective dorsal cells, spatially facing and preceding the onset of nodal transcription. We report that Hbox12 misexpression provokes DV abnormalities, attenuating nodal and nodal-dependent transcription. Reciprocally, impairing hbox12 function disrupts DV polarity by allowing ectopic expression of nodal. Clonal loss-of-function, inflicted by blastomere transplantation or gene-transfer assays, highlights that DV polarization requires Hbox12 action in dorsal cells. Remarkably, the localized knock-down of nodal restores DV polarity of embryos lacking hbox12 function. Finally, we show that hbox12 is a dorsal-specific negative modulator of the p38-MAPK activity, which is required for nodal expression. Altogether, our results suggest that Hbox12 function is essential for proper positioning of the DV organizer.

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Regulatory sequences driving expression of the sea urchin Otp homeobox gene in oral ectoderm cells

Gene Expression Patterns ◽

10.1016/j.modgep.2006.06.001 ◽

2007 ◽

Vol 7 (1-2) ◽

pp. 124-130 ◽

Cited By ~ 11

Author(s):

Vincenzo Cavalieri ◽

Maria Di Bernardo ◽

Giovanni Spinelli

Keyword(s):

Sea Urchin ◽

Homeobox Gene ◽

Regulatory Sequences ◽

Oral Ectoderm

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SpMyb functions as an intramodular repressor to regulate spatial expression of CyIIIa in sea urchin embryos

Development ◽

10.1242/dev.124.23.4717 ◽

1997 ◽

Vol 124 (23) ◽

pp. 4717-4727 ◽

Cited By ~ 2

Author(s):

J.A. Coffman ◽

C.V. Kirchhamer ◽

M.G. Harrington ◽

E.H. Davidson

Keyword(s):

Transcription Factors ◽

Sea Urchin ◽

Regulatory Region ◽

Ectopic Expression ◽

Amino Acid Sequences ◽

Target Site ◽

Cdna Clones ◽

Sequence Information ◽

Oral Ectoderm ◽

Myb Domain

The CyIIIa actin gene of Strongylocentrotus purpuratus is transcribed exclusively in the embryonic aboral ectoderm, under the control of 2.3 kb cis-regulatory domain that contains a proximal module that controls expression in early embryogenesis, and a middle module that controls expression in later embryogenesis. Previous studies demonstrated that the SpRunt-1 target site within the middle module is required for the sharp increase in CyIIIa transcription which accompanies differentiation of the aboral ectoderm, and that a negative regulatory region near the SpRunt-1 target site is required to prevent ectopic transcription in the oral ectoderm and skeletogenic mesenchyme. This negative regulatory region contains a consensus binding site for the myb family of transcription factors. In vitro DNA-binding experiments reveal that a protein in blastula-stage nuclei interacts specifically with the myb target site. Gene transfer experiments utilizing CyIIIa reporter constructs containing oligonucleotide substitutions indicate that this site is both necessary and sufficient to prevent ectopic expression of CyIIIa. Synthetic oligonucleotides containing the myb target site were used to purify a protein from sea urchin embryo nuclear extracts by affinity chromatography. This protein is immunoprecipitated by antibodies specific to the evolutionarily conserved myb domain, and amino acid sequences obtained from the purified protein were found to be identical to sequences within the myb domain. Sequence information was used to obtain cDNA clones of SpMyb, the S. purpuratus member of the myb family of transcription factors. Through interactions within the middle module, SpMyb functions to repress activation of CyIIIa in the oral ectoderm and skeletogenic mesenchyme.

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Effects of Glyphosate-Based and Derived Products on Sea Urchin Larval Development

Journal of Marine Science and Engineering ◽

10.3390/jmse8090661 ◽

2020 ◽

Vol 8 (9) ◽

pp. 661

Author(s):

Davide Asnicar ◽

Costanza Cappelli ◽

Ahmad Safuan Sallehuddin ◽

Nur Atiqah Maznan ◽

Maria Gabriella Marin

Keyword(s):

Larval Development ◽

Sea Urchin ◽

Marine Invertebrates ◽

Parent Compound ◽

Paracentrotus Lividus ◽

Marine Species ◽

Negative Effects ◽

Aminomethylphosphonic Acid ◽

Main Degradation Product ◽

Herbicide Glyphosate

Despite the widespread use of herbicide glyphosate in cultivation, its extensive runoff into rivers and to coastal areas, and the persistence of this chemical and its main degradation product (aminomethylphosphonic acid, AMPA) in the environment, there is still little information on the potential negative effects of glyphosate, its commercial formulation Roundup® and AMPA on marine species. This study was conducted with the aim of providing a comparative evaluation of the effects of glyphosate-based and its derived chemicals on the larval development of the sea urchin Paracentrotus lividus, thus providing new data to describe the potential ecotoxicity of these contaminants. In particular, the effects on larval development, growth and metabolism were assessed during 48 h of exposure from the time of egg fertilization. The results confirm that AMPA and its parent compound, glyphosate have similar toxicity, as observed in other marine invertebrates. However, interestingly, the Roundup® formulation seemed to be less toxic than the glyphosate alone.

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Biometric characteristics of the wild population of sea urchin Paracentrotus lividus (Lamarck, 1816) on the Tunisian coast

Thalassas An International Journal of Marine Sciences ◽

10.1007/s41208-021-00301-8 ◽

2021 ◽

Author(s):

F. Sellem ◽

B. Bouhaouala-Zahar

Keyword(s):

Sea Urchin ◽

Wild Population ◽

Multivariable Analysis ◽

Paracentrotus Lividus ◽

Biometric Data ◽

Relative Growth ◽

Tunisian Coast ◽

Population Discrimination ◽

Positive Growth ◽

Negative Growth

AbstractThe present study was conducted to provide biometric data of the edible sea urchin Paracentrotus lividus along the Tunisian coastline where thirteen marine localities were selected randomly. A total of 653 individuals were collected and their metric and weight measurements were recorded. The size distribution of the different samples was determined and relative growth expressions were deduced. Data analysis showed that all localities’ samples of the wild population were dominated by one-size class, except Port Prince and Haouaria. Interestingly, only diameter-height relationships (D-H) were different between the geographical localities. Diameter-weight relationships (D-TW and D-TWTE) revealed a significant negative growth for all the localities, with the exception of Gammarth which showed positive growth for total weight (D-TW). Moreover, the multivariable analysis revealed divergences and/or similarities between metric and weight variables. Altogether, data highlights the inter-population discrimination with respect to geographic localization and clear segregation between the northern and the eastern localities demonstrated the plasticity of the species.

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