Search results for "sea urchins"
showing 10 items of 135 documents
Regulation of the sea urchin early H2A histone gene expression depends on the modulator element and on sequences located near the 3' end
1999
Abstract Transcription of the sea urchin early histone genes occurs transiently during early cleavage, reaching the maximum at the morula stage and declining to an undetectable level at the gastrula stage. To identify the regulatory elements responsible for the timing and the levels of transcription of the H2A gene, we used promoter binding studies in nuclear extracts and microinjection of a CAT transgene driven by the early H2A promoter. We found that morula and gastrula nuclear proteins produced indistinguishable DNase I footprint patterns on the H2A promoter. Two sites of interactions, centred on the modulator/enhancer and on the CCAAT box respectively, were detected. Deletion of the mod…
The modulator is a constitutive enhancer of a developmentally regulated sea urchin histone H2A gene.
2002
Going back to the late 1970s and early 1980s, we trace the Xenopus oocyte microinjection experiments that led to the emergence of the concept of “modulator”. The finding that the modulator could transactivate transcription from far upstream and in either orientation suggested that a new genetic element, different from the classical prokaryotic promoter sequences, had been discovered. This particular enhancer transactivates transcription of the sea urchin early (α) histone H2A gene which is regulated in early sea urchin development. We summarise the data from sea urchin microinjection experiments that confirm and extend the results obtained with Xenopus oocytes. We conclude that the H2A enha…
Impairing Otp homeodomain function in oral ectoderm cells affects skeletogenesis in sea urchin embryos
2003
AbstractIn the sea urchin embryo skeletogenesis is the result of a complex series of molecular and cellular events that coordinate the morphogenetic process. Past and recent evidence strongly indicate that skeletal initiation and growth are strictly dependent on signals emanating from the oral ectodermal wall. As previously suggested, Orthopedia (Otp), a homeodomain-containing transcription factor specifically expressed in a small subset of oral ectoderm cells, might be implicated in this signalling pathway. In this study, we utilize three different strategies to address the issue of whether Otp is an upstream regulator of sketelogenesis. We describe the effects of microinjection of Otp mor…
Aberrant gene expression profiles in Mediterranean sea urchin reproductive tissues after metal exposures
2019
Abstract Marine organisms are simultaneously exposed to numerous pollutants, among which metals probably represent the most abundant in marine environments. In order to evaluate the effects of metal exposure at molecular level in reproductive tissues, we profiled the sea urchin transcriptional response after non-lethal exposures using pathway-focused mRNA expression analyses. Herein, we show that exposures to relatively high concentrations of both essential and toxic metals hugely affected the gonadic expression of several genes involved in stress-response, detoxification, transcriptional and post-transcriptional regulation, without significant changes in gonadosomatic indices. Even though …
Characterization of a new member of the sea urchin Paracentrotus lividus hsp70 gene family and its expression
1992
We have sequenced a second gene of the hsp70 family derived from a genomic clone of the sea urchin, Paracentrotus lividus. The structure of this gene, named hsp70IV gene, is interrupted by one intron and differs from the previously analyzed sea urchin hsp70II gene, which contains several introns. Two open reading frames of hsp70IV gene encode a predicted protein of 639 amino acids with an M(r) of 69,672. The 5' flanking region of the gene contains a putative TATA element, three heat-shock elements made up of some arrays of the 5-bp units, NGAAN and NTTCN (N = A,C,G or T), a canonic consensus sequence for binding of the regulatory activating transcription factor (ATF), and a purine box. The …
Could the acid-base status of Antarctic sea urchins indicate a better-than-expected resilience to near-future ocean acidification?
2015
13 pages; International audience; Increasing atmospheric carbon dioxide concentration alters the chemistry of the oceans towards more acidic conditions. Polar oceans are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the oceans' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to ocean acidification in metazoans is first linked to acid–base regulation capacities of the extracellular fluids. No infor…
Sea Urchin Mitochondrial Matrix Contains a 56-kDa Chaperonine-like Protein
1997
Abstract Paracentrotus lividus mitochondrial matrix contains a constitutive hsp of 56-KDa which cross reacts with a serum anti-hsp-60 chaperonine from yeast mitochondria. The localization of hsps preexisting or newly synthesized in different subcellular fractions of gastrula embryos is also analyzed by two-dimensional electrophoresis.
Spatially restricted expression of PlOtp, a Paracentrotus lividus Orthopedia-related homeobox gene, is correlated with oral ectodermal patterning and…
1999
ABSTRACT 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 abund…
Synthesis of heat-shock proteins in developing sea urchins.
1981
Heating sea urchin embryos at 31°C greatly reduces the synthesis of the bulk proteins, whereas it highly stimulates the synthesis of some new proteins, the main ones being two closely migrating proteins of about 70,000 daltons. The production of heat-shock proteins is obtained only if the embryos are heated after hatching. Stages which produce heat-shock proteins survive heating, whereas earlier stages, not producing heat-shock proteins, do not survive. Heat-shock proteins are not produced in the presence of actinomycin D.
Nickel, lead, and cadmium induce differential cellular responses in sea urchin embryos by activating the synthesis of different HSP70s.
2004
Treatment with heavy metals, such as nickel, lead or cadmium, elicits different cellular stress responses according to the metal used and the length of treatment. In Paracentrotus lividus embryos the inducible forms of HSP70 (HSP70/72) are different in molecular mass from the constitutively expressed HSP75, and they can be used as markers of cellular stress. Even a short treatment with each metal induces the synthesis of HSP70/72 which remain stable for at least 20 h and differ little in their isoelectric points. Continuous treatment from fertilization with nickel or lead produces late irregular pluteus embryos, with peak HSP70/72 synthesis at blastula followed by the arrest of synthesis by…