Search results for "Paracentrotus Lividus."

Studies on sea urchin oocytes. II. Synthesis of RNA during oogenesis.

1972

Abstract Isolated oocytes of the sea urchin Paracentrotus lividus actively incorporate 3H-uridine into RNA. Labeled RNA was analysed by sucrose gradient and acrylamide gel electrophoresis following cell fractionation. Much of the radioactivity is incorporated at the nucleolar level in the form of rRNA precursors. The kinetics of maturation of these latter suggests that this occurs at a slower rate than during embryogenesis. Other non-nucleolar RNA classes are also actively labelled and retained in the nucleus for many hours. These results are confirmed by an autoradiographic investigation.

Ectoderm restricted expression of the TRIM-containing factor Strim1 directs the migration, aggregation and terminal differentiation of mesenchymal ce…

2011

Constitutive hsp70 is essential to mitosis during early cleavage of Paracentrotus lividus embryos: The blockage of constitutive hsp70 impairs mitosis

1999

Localization of constitutive hsp70 in eggs and early embryos of sea urchin Paracentrotus lividus is shown by means of in situ immunostaining. An accumulation of this protein is shown in the mitotic structures (asters, spindles and centrosomes). Microinjection of anti-hsp70 antibodies into eggs causes impairment of formation of mitotic structures and of cell division. This impairment goes from a complete mitotic block, to irregular mitotic apparatus formation with irregular cleavage, depending upon the antibody concentration. The localization of hsp70 after antibody microinjection is also described. Blockage of mitotic apparatus formation by nocodazole also blocks the concentration of hsp70 …

Promoter activity of the sea urchin (Paracentrotus lividus) nucleosomal H3 and H2A and linker H1 a-histone genes is modulated by enhancer and chromat…

2009

Core promoters and chromatin insulators are key regulatory elements that may direct a transcriptional enhancer to prefer a specific promoter in complex genetic loci. Enhancer and insulator flank the sea urchin (Paracentrotus lividus) alpha-histone H2A transcription unit in a tandem repeated cluster containing the five histone genes. This article deals with the specificity of interaction between the H2A enhancer-bound MBF-1 activator and histone gene promoters, and with the mechanism that leads the H1 transcripts to peak at about one-third of the value for nucleosomal H3 and H2A mRNAs. To this end, in vivo competition assays of enhancer and insulator functions were performed. Our evidence su…

Sea urchin neural alpha 2 tubulin gene: isolation and promoter analysis

2004

Abstract Expression of Tα2 gene, during sea urchin Paracentrotus lividus development, is spatially and temporally regulated. In order to characterize this gene, we isolated the relevant genomic sequences and scanned the isolated 5 ′ -flanking region in searching for cis -regulatory elements required for proper expression. Gel mobility shift and footprinting assays, as well as reporter gene (CAT and β-gal) expression assays, were used to address cis -regulatory elements involved in regulation. Here we report that an upstream 5 ′ -flanking fragment of PlTα2 gene drives temporal expression of reporter genes congruent with that of endogenous Tα2 gene. The fragment contains cis -elements able to…

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 …

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…

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…

Rapid changes in heat-shock cognate 70 levels, heat-shock cognate phosphorylation state, heat-shock transcription factor, and metal transcription fac…

2010

The aim of the present study was to analyze and compare the effects of several metals on the embryos of the sea urchin Paracentrotus lividus, a key species within the Mediterranean Sea ecosystem. Embryos were continuously exposed from fertilization to the following metals: 0.6 mg/l copper, 3 mg/l lead, and 6 mg/l nickel. The embryos were then monitored for metal responses at the gastrula stage, which occurred 24 h after exposure. A biochemical multi-experimental approach was taken and involved the investigation of the levels of HSC70 expression and the involvement of heat shock factor (HSF) and/or metal transcription factor (MTF) in the response. Immunoblotting assays and electrophoretic mo…