Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ECHINODERMS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMedDate not supplied

[Single copy and repetitive nucleotide sequences in the genome of Echinodermata. II. Nucleotide sequence divergence of DNA of echinoderms].

The degree of divergence of short and long repetitive DNA sequences and single copy DNA of five Echinodermata species (sea urchins, starfish, sea-cucumber) was studied by the method of molecular hybridization. Different fractions of 3H-DNA of the sea urchin Strongylocentrotus intermedius were hybridized with the DNA of other species. Thermal stability of the hybridized DNA molecules was determined. The results obtained suggest that short repetitive sequences were most conservative during the evolution of Echinodermata. Single copy DNA fractions of closely related sea urchin species (S. intermedius and S. nudus) have more homologous sequences than long repetitive DNA fractions of the same species. The DNA of evolutionary distant species (sea urchin and starfish) have more homologous long repetitive sequences than the single copy ones. All DNA fractions of S. intermedius have sequences hybridized with the DNA of all other species studied: short repetitive sequences--55%, long repetitive sequences--20%, single copy sequences--12%.

Animals↗
PubMedDate not supplied

[Divergence of repetitive DNA sequences in echinoderms. II. Comparison of sequences with a low degree of intragenome divergence].

The DNA-DNA hybridization method was used to estimate the value of intergenomic divergence of sequences of middle and thermostable fractions among representatives of three classes of echinodermata (Echinoidea, Asterodea and Holothurioidea), and also representative of another type, ascidian Halocynthia aurantium. The results obtained were compared with analogous measurements carried out with a fraction of thermolabile reiterating sequences. It was found that in each of the three fractions there are sequences that are inherent in DNA of all the species compared. The proportion of these sequences in the thermolabile fraction is larger than that in the other two. The degree of divergence of the common sequences were estimated by the temperature stability of hybrid duplexes. Comparison of the related species shows that it is higher for the sequences of the thermostable fraction, whereas the sequences that are inherent in distant species diverged more markedly in the thermolabile fraction. Part of the sequences in the thermostable fraction form hybrid duplexes with a high melting temperature, even if one of the DNAs is from distant species. No such sequences were found in the thermolabile fraction. The results obtained are discussed from the point of view of the functional role of various groups of reiterating sequences are of the significance of these data for comprehension of the evolutional history of species.

Animals↗
PubMed1994

Selective inhibition of exoplasmic membrane fusion in echinoderm gametes with jaspisin, a novel antihatching substance isolated from a marine sponge.

A specific inhibitor of fertilization of the sea urchin Hemicentrotus pulcherrimus was isolated from the extract of the marine sponge, Jaspis species. Chemical and spectral data of the purified substance, which was designated jaspisin, showed that it is a novel substance with the structure of sodium (E)-5,6-dihydroxystyryl sulfate. Jaspisin at 15 micrograms/ml inhibited exoplasmic fusion of the plasma membrane of acrosome-reacted sperm with the plasma membrane of the egg; it did not affect either the acrosome reaction in sperm or the egg cortical reaction, both of which involve endoplasmic membrane fusion events. When a fertilized egg was cultured in jaspisin, the embryo developed through the mesenchymal blastula stage. However, it was unable to hatch from the fertilization envelope, and spiculogenesis, in which cell-cell fusion of primary mesenchyme cells is involved, was prevented. Jaspisin at 8.6 micrograms/ml inhibited half the activity of hatching enzyme, a kind of Zn(2+)-dependent metalloendoproteinases. Because Zn(2+)-activated metalloendoproteinases are suggested to be involved in both sperm-egg fusion and fusion of primary mesenchyme cells (Lennarz, W.J., and Strittmatter, W.J. (1991) Biochim. Biophys. Acta 1071, 149-158), one of the possible explanations of the jaspisin effects is that the sulfate inhibits these cellular events through blockage of Zn(2+)-activated metalloendoproteinases that are involved in membrane fusion processes.

Animals↗
PubMed2005

The complete mitochondrial genomes of the sea lily Gymnocrinus richeri and the feather star Phanogenia gracilis: signature nucleotide bias and unique nad4L gene rearrangement within crinoids.

Complete DNA sequences have been determined for the mitochondrial genomes of the crinoids Phanogenia gracilis (15892 bp) and Gymnocrinus richeri (15966 bp). The mitochondrial genetic map of the stalkless feather star P. gracilis is identical to that of the comatulid feather star Florometra serratissima (Scouras, A., Smith, M.J., 2001. Mol. Biol. Evol. 18, 61-73). The mitochondrial gene order of the stalked crinoid G. richeri differs from that of F. serratissima and P. gracilis by the transposition of the nad4L protein gene. The G. richeri nad4L mitochondrial map position is unique among metazoa and is likely a derived feature in this stalked crinoid. Nucleotide compositional analyses of protein genes encoded on the major sense strand confirm earlier conclusions regarding a crinoid-distinctive T over C bias. All three crinoids exhibit high T levels in third codon positions, whereas other echinoderm classes favor A or C in the third codon position. The nucleotide bias is reflected in the relative synonymous codon usage patterns of crinoids versus other echinoderms. We suggest that the nucleotide bias of crinoids, in comparison to other echinoderms, indicates that a physical inversion of the origin of replication has occurred in the crinoid lineage. Evolutionary rate tests support the use of the cytochrome b (cob) gene in molecular phylogenetic analyses of echinoderms. A consensus echinoderm tree was generated based on cytochrome b nucleotide alignments that placed the asteroids as a sister group to a clade containing the ophiuroids and the (echinoids+holothuroids) with the crinoids basal to the rest of the echinoderm classes: [Crinoid,(Asteroid,(Ophiuroid,(Echinoid,Holothuroid)))].

Animals↗
PubMed2006

A genome-wide analysis of biomineralization-related proteins in the sea urchin Strongylocentrotus purpuratus.

Biomineralization, the biologically controlled formation of mineral deposits, is of widespread importance in biology, medicine, and engineering. Mineralized structures are found in most metazoan phyla and often have supportive, protective, or feeding functions. Among deuterostomes, only echinoderms and vertebrates produce extensive biomineralized structures. Although skeletons appeared independently in these two groups, ancestors of the vertebrates and echinoderms may have utilized similar components of a shared genetic "toolkit" to carry out biomineralization. The present study had two goals. First, we sought to expand our understanding of the proteins involved in biomineralization in the sea urchin, a powerful model system for analyzing the basic cellular and molecular mechanisms that underlie this process. Second, we sought to shed light on the possible evolutionary relationships between biomineralization in echinoderms and vertebrates. We used several computational methods to survey the genome of the purple sea urchin Strongylocentrotus purpuratus for gene products involved in biomineralization. Our analysis has greatly expanded the collection of biomineralization-related proteins. We have found that these proteins are often members of small families encoded by genes that are clustered in the genome. Most of the proteins are sea urchin-specific; that is, they have no apparent homologues in other invertebrate deuterostomes or vertebrates. Similarly, many of the vertebrate proteins that mediate mineral deposition do not have counterparts in the S. purpuratus genome. Our findings therefore reveal substantial differences in the primary sequences of proteins that mediate biomineral formation in echinoderms and vertebrates, possibly reflecting loose constraints on the primary structures of the proteins involved. On the other hand, certain cellular and molecular processes associated with earlier events in skeletogenesis appear similar in echinoderms and vertebrates, leaving open the possibility of deeper evolutionary relationships.

Amino Acid Sequence↗
PubMed2006

Building divergent body plans with similar genetic pathways.

Deuterostome animals exhibit widely divergent body plans. Echinoderms have either radial or bilateral symmetry, hemichordates include bilateral enteropneust worms and colonial pterobranchs, and chordates possess a defined dorsal-ventral axis imposed on their anterior-posterior axis. Tunicates are chordates only as larvae, following metamorphosis the adults acquire a body plan unique for the deuterostomes. This paper examines larval and adult body plans in the deuterostomes and discusses two distinct ways of evolving divergent body plans. First, echinoderms and hemichordates have similar feeding larvae, but build a new adult body within or around their larvae. In hemichordates and many direct-developing echinoderms, the adult is built onto the larva, with the larval axes becoming the adult axes and the larval mouth becoming the adult mouth. In contrast, indirect-developing echinoderms undergo radical metamorphosis where adult axes are not the same as larval axes. A second way of evolving a divergent body plan is to become colonial, as seen in hemichordates and tunicates. Early embryonic development and gastrulation are similar in all deuterostomes, but, in chordates, the anterior-posterior axis is established at right angles to the animal-vegetal axis, in contrast to hemichordates and indirect-developing echinoderms. Hox gene sequences and anterior-posterior expression patterns illuminate deuterostome phylogenetic relationships and the evolution of unique adult body plans within monophyletic groups. Many genes that are considered vertebrate 'mesodermal' genes, such as nodal and brachyury T, are likely to ancestrally have been involved in the formation of the mouth and anus, and later were evolutionarily co-opted into mesoderm during vertebrate development.

Animals↗
PubMed2005

Molecular characterisation of SALMFamide neuropeptides in sea urchins.

The SALMFamides are a family of neuropeptides found in species belonging to the phylum Echinodermata. Members of this family have been identified in starfish (class Asteroidea) and in sea cucumbers (class Holothuroidea) but not in other echinoderms. Our aim here was to characterise SALMFamide neuropeptides in sea urchins (class Echinoidea). Radioimmunoassays for the starfish SALMFamides S1 and S2 were used to test for related peptides in whole-body acetone extracts of the sea urchin Echinus esculentus. Fractionation of extracts using high performance liquid chromatography (HPLC) revealed several peaks of SALMFamide-like immunoreactivity, with two S2-like immunoreactive peaks (3 and 4) being the most prominent. However, peak 4 could not be purified to homogeneity and although peak 3 was purified, only a partial sequence (MRYH) could be obtained. An alternative strategy for identification of echinoid SALMFamides was provided by sequencing the genome of the sea urchin Strongylocentrotus purpuratus. Analysis of whole-genome shotgun sequence data using the Basic Local Alignment Search Tool (BLAST) identified a contig (347664) that contains a coding region for seven putative SALMFamide neuropeptides (PPVTTRSKFTFamide, DAYSAFSFamide, GMSAFSFamide, AQPSFAFamide, GLMPSFAFamide, PHGGSAFVFamide and GDLAFAFamide), which we have named SpurS1-SpurS7, respectively. Three of these peptides (SpurS1-3) have the C-terminal sequences TFamide or SFamide, which are identical or similar to the C-terminal region of the starfish SALMFamide S2. This may explain the occurrence of several S2-like immunoreactive peptides in extracts of Echinus esculentus. Detailed analysis of the sequence of contig 347664 indicated that the SALMFamide gene in Strongylocentrotus purpuratus comprises two exons, with the first exon encoding a signal peptide sequence and the second exon encoding SpurS1-SpurS7. Characterisation of this gene is important because it is the first echinoderm neuropeptide precursor sequence to be identified and, more specifically, it provides our first insight into the structure and organisation of a SALMFamide gene in an echinoderm. In particular, it has revealed a hitherto unknown complexity in the diversity of SALMFamide neuropeptides that may occur in an echinoderm species because all previous studies, which relied on peptide purification and sequencing, revealed only two SALMFamide neuropeptides in each species examined. It now remains to be established whether or not the occurrence of more than two SALMFamides in Strongylocentrotus purpuratus is a feature that is peculiar to this species and to echinoids in general or is more widespread across the phylum Echinodermata. Identification of SpurS1-SpurS7 provides the basis for comparative analysis of the physiological actions of these peptides in sea urchins and for exploitation of the sea urchin genome sequence to identify the receptor(s) that mediate effects of SALMFamides in echinoderms.

Amino Acid Sequence↗
PubMed2003

Neural expression of the Huntington's disease gene as a chordate evolutionary novelty.

Huntington's disease is a progressive neuro-degenerative disorder in humans, which is scharacterized by onset of dementia, muscular ataxia, and death. Huntington's disease is caused by the expansion of the polyglutamine (polyQ) tract in the N-terminus of the HD protein (Huntingtin). CAG expansion is a dominant gain of function mutation that affects striated neurons in the brain (Cattaneo, 2003, News Physiol Sci 18:34). The evolutionary origins of the vertebrate Hd gene are not well understood. In order to address the evolutionary history of the Hd gene, we have cloned and characterized the expression of the Hd gene in two invertebrate deuterostomes, an echinoderm and an ascidian, and have examined the expression patterns in a phylogenetic context. Echinoderms are basal deuterostomes and ascidians are basal chordates; both are useful for understanding the origins of and evolutionary trends in genes important in vertebrates such as the Huntigton's disease gene. Expression of Hd RNA is detected at all stages of development in both the echinoderm and ascidian studied. In the echinoderm Heliocidaris erythrogramma, Hd is expressed in coelomic mesodermal tissue derivatives, but not in the central nervous system. In the ascidian Halocynthia roretzi expression is located in both mesoderm and nervous tissue. We suggest that the primitive deuterostome expression pattern is not neural. Thus, neural expression of the Hd gene in deuterostomes may be a novel feature of the chordate lineage, and the original role(s) of HD in deuterostomes may have been non-neural.

Amino Acid Sequence↗
PubMed2005

Mutable collagenous tissue: overview and biotechnological perspective.

The mutable collagenous tissue (MCT) of echinoderms can undergo extreme changes in passive mechanical properties within a timescale of less than 1 s to a few minutes, involving a mechanism that is under direct neural control and coordinated with the activities of muscles. MCT occurs at a variety of anatomical locations in all echinoderm classes, is involved in every investigated echinoderm autotomy mechanism, and provides a mechanism for the energy-sparing maintenance of posture. It is therefore crucially important for the biology of extant echinoderms. This chapter summarises current knowledge of the physiology and organisation of MCT, with particular attention being given to its molecular organisation and the molecular mechanism of mutability. The biotechnological potential of MCT is discussed. It is argued that MCT could be a source of, or inspiration for, (1) new pharmacological agents and strategies designed to manipulate therapeutically connective tissue mechanical properties and (2) new composite materials with biomedical applications.

Amino Acid Sequence↗