scholarly journals Marked Changes in the Ribonuclease Activity of Mature and Immature Gonads of Sea Urchins Hemicentrotus pulcherrimus and Anthocidaris crassispina

2008 ◽  
Vol 31 (9) ◽  
pp. 1659-1662
Author(s):  
Akihiro Sanda ◽  
Masato Kiyomoto ◽  
Masanori Iwama ◽  
Kazuko Ohgi ◽  
Masachika Irie
Keyword(s):  
Sea Urchins ◽  
Ribonuclease Activity ◽  
Hemicentrotus Pulcherrimus ◽  
Anthocidaris Crassispina

Cellular analyses of sea urchin metamorphosis

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S77-S78
Author(s):  
Yukiko Sato ◽  
Ikuko Yazaki
Keyword(s):  
Electron Microscopy ◽  
Fatty Acids ◽  
Squamous Epithelium ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Chromatin Condensation ◽  
Environmental Cues ◽  
Nuclear Chromatin ◽  
Intracellular Changes ◽  
Hemicentrotus Pulcherrimus

Larvae of marine invertebrates undergo metamorphosis in response to environmental cues (Chia & Burke, 1978). In sea urchins, free fatty acids (Kitamura et al., 1993), dibromomethane (Taniguchi et al., 1994), pheromonal peptides (Burke, 1984) and L-glutamine (Yazaki & Harashima, 1994; Yazaki, 1995) have been known as metamorphosis-inducing substances. The mechanisms by which cells respond to these cues and how the larval tissues are absorbed have not been clear, however. In the present study, we used L-glutamine (Gln) and a natural cue, green algae (Ulvella sp.), to induce metamorphosis of Hemicentrotus pulcherrimus and Anthocidaris crassispina, and investigated the intracellular changes during metamorphosis.After being subjected to 10−5–10−3 M Gln for 10–24 h, larvae cease swimming, settle, begin to retract their larval arms, extrude the primary podia and finally evert their echinus rudiment (ER). In H. pulcherrimus, larvae retracted their arms from 6 h to 24 h after the start of Gln treatment and then everted the ER. A. crassispina larvae underwent similar processes to those of H. pulcherrimus. The larval surface is composed of squamous epithelium and columnar epithelium. The epithelium of the ciliary bands or epaulets is columnar.In the squamous epithelium, the nuclear chromatin in the larval arms and body, and in the oesophagus, markedly condensed after treatment with Gln for 24 h. Electron microscopy revealed swelling of both nuclei and mitochondria, while their membranes seemed to be intact. In the cytoplasm, lipid-like structures and electron-dense substances appeared. A further 24 h after Gln treatment, the chromatin condensation had progressed. Most nuclei in which chromatin had condensed were positive to the TUNEL assay, which detects DNA fragmentation. These results suggest that cell death in the squamous epithelium is apoptotic rather than necrotic.

An approach to the phylogeny of the order Echinoida using interf amily hybrids

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S88-S89
Author(s):  
Masayoshi Hata
Keyword(s):  
Shallow Waters ◽  
Strongylocentrotus Intermedius ◽  
Morphological Criteria ◽  
The Family ◽  
Tripneustes Gratilla ◽  
Echinometra Mathaei ◽  
Strongylocentrotus Nudus ◽  
Hemicentrotus Pulcherrimus ◽  
Anthocidaris Crassispina

Order Echinoida in Japan is now classified into the following five families: Temnopleuridae, Toxo-pneustidae, Strongylocentrotidae, Echinometridae and Parasaleniidae. With the exception of the Parasaleniidae, four of the families are commonly found in shallow waters in Japan. Interrelationships among these four families have been extensively studied by many workers using morphological criteria or at the biochemical and molecular levels, and four different theories have been proposed (Jensen, 1981; Smith, 1984; Mortensen, 1928–1951; Shigei, 1986; Matsuoka, 1988). To examine these theories, I attempted to obtain hybrids using 14 species (4 species of the family Temnopleuridae: Temnopleurus toreumaticus, Temnopleurus hardwickii, Temnopleurus reeversii and Mespilia globulus; 3 species of the family Toxopneustidae: Toxopneustes pileolus, Tripneustes gratilla and Pseudoboletia maculata; 4 species of the family Strongylocentrotidae: Strongylocentrotus intermedius, Strongylocentrotus nudus, Hemicentrotus pulcherrimus and Pseudocentrotus depressus; and 3 species of the family Echinometridae: Anthocidaris crassispina, Echinostrephus aciculatus and Echinometra mathaei).

The guanylyl cyclase receptors

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S24-S25 ◽  
Author(s):  
David L. Garbers
Keyword(s):  
Guanylyl Cyclase ◽  
Sea Urchins ◽  
Active Material ◽  
Conditioned Media ◽  
Active Principle ◽  
New Paradigm ◽  
Arbacia Punctulata ◽  
Sea Urchin Egg ◽  
Suzuki Group ◽  
Hemicentrotus Pulcherrimus

In the early 1980s both our group (Hansbrough & Garbers, 1981; Garbers et al., 1982) and that of Norio Suzuki (Suzuki et al., 1981) identified the active material in sea urchin egg conditioned media that could stimulate sperm motility and metabolism. In the sea urchins Hemicentrotus pulcherrimus or Strongylocentrotus purpuratus, the active material was a small peptide that we named speract, and the Suzuki group named this and subsequent peptides SAPs, for sperm activating peptides. Subsequently, both groups identified other peptides (see Suzuki & Yoshino, 1992 for review), one of the most interesting being one named resact, the active material in Arbacia punctulata egg conditioned media. This peptide turned out to be the first animal sperm chemoattractant identified (Ward et al., 1985a). A peptide also turned out to be the active principle that explained previous observations of Ward and Vacquier (Ward et al., 1985b; Suzuki et al., 1984) that egg conditioned media could cause the rapid dephosphorylation of a major membrane protein of spermatozoa. The apparent receptor for resact was later identified as a guanylyl cyclase, establishing a new paradigm for low-molecular-weight second messenger signalling, and the major phosphoprotein regulated by resact was also the receptor itself.

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