Sperm-induced local [Ca2+]i rise separated from the Ca2+ wave in sea urchin eggs in the presence of a gamete fusion inhibitor, jaspisin

Development ◽  
1998 ◽  
Vol 125 (2) ◽  
pp. 293-300 ◽  
Author(s):  
T. Mohri ◽  
S. Miyazaki ◽  
H. Shirakawa ◽  
S. Ikegami
Keyword(s):  
Membrane Fusion ◽  
Sea Urchin ◽  
Focal Plane ◽  
Attachment Site ◽  
Fusion Inhibitor ◽  
Low Doses ◽  
Inward Current ◽  
Egg Membrane ◽  
Hemicentrotus Pulcherrimus ◽  
Stimulation Of

An increase in intracellular Ca2+ concentration ([Ca2+]i) at a focal plane was recorded simultaneously with sperm-egg binding and membrane current upon insemination of sea urchin Hemicentrotus pulcherrimus eggs. No change in current and [Ca2+]i occurred in the presence of jaspisin, a novel substance that inhibits metallo-endoproteinase and sperm-egg membrane fusion (S. Ikegami, H. Kobayashi, Y. Myotoishi, S. Ohta and K. H. Kato (1994) J. Biol. Chem. 269, 23262–23267). With low doses of jaspisin, a spermatozoon first produced a step inward current (I(on)) as an indication of gamete membrane fusion and then induced a local [Ca2+]i rise at the site of sperm attachment 6–10 seconds after I(on). The sperm, however, soon detached from the egg. Increasing inward current was abruptly cut off (I(off)) within 9–15 seconds and the local [Ca2+]i rise began to decline 1–3 seconds after I(off). In most cases, no further responses or an elevation of fertilization envelope (FE) occurred. In some cases, [Ca2+]i at the sperm attachment site increased again even after the sperm detached and triggered a Ca2+ wave which caused an activation current and FE formation. This recording of a gamete membrane-fusion-induced local [Ca2+]i rise, separated from the Ca2+ wave, is a key phenomenon for elucidating the initial sperm stimulation of the egg at fertilization.

scholarly journals Prefusion structure of human cytomegalovirus glycoprotein B and structural basis for membrane fusion

2021 ◽  
Vol 7 (10) ◽  
pp. eabf3178
Author(s):  
Yuhang Liu ◽  
Kyle P. Heim ◽  
Ye Che ◽  
Xiaoyuan Chi ◽  
Xiayang Qiu ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Human Cytomegalovirus ◽  
Transmembrane Domain ◽  
Proximal Region ◽  
Viral Envelope ◽  
Vaccine Antigen ◽  
Glycoprotein B ◽  
Structural Basis ◽  
Fusion Inhibitor ◽  
Host Cell Membrane

Human cytomegalovirus (HCMV) causes congenital disease with long-term morbidity. HCMV glycoprotein B (gB) transitions irreversibly from a metastable prefusion to a stable postfusion conformation to fuse the viral envelope with a host cell membrane during entry. We stabilized prefusion gB on the virion with a fusion inhibitor and a chemical cross-linker, extracted and purified it, and then determined its structure to 3.6-Å resolution by electron cryomicroscopy. Our results revealed the structural rearrangements that mediate membrane fusion and details of the interactions among the fusion loops, the membrane-proximal region, transmembrane domain, and bound fusion inhibitor that stabilized gB in the prefusion state. The structure rationalizes known gB antigenic sites. By analogy to successful vaccine antigen engineering approaches for other viral pathogens, the high-resolution prefusion gB structure provides a basis to develop stabilized prefusion gB HCMV vaccine antigens.

scholarly journals Involvement of Huntingtin in Development and Ciliary Beating Regulation of Larvae of the Sea Urchin, Hemicentrotus pulcherrimus

2021 ◽  
Vol 22 (10) ◽  
pp. 5116
Author(s):  
Hideki Katow ◽  
Tomoko Katow ◽  
Hiromi Yoshida ◽  
Masato Kiyomoto
Keyword(s):  
Sea Urchin ◽  
The Body ◽  
Brdu Incorporation ◽  
Wild Type ◽  
Blastula Stage ◽  
Ciliary Beating ◽  
Marker Proteins ◽  
Disease Protein ◽  
Pattern Regulation ◽  
Hemicentrotus Pulcherrimus

The multiple functions of the wild type Huntington’s disease protein of the sea urchin Hemicentrotus pulcherrimus (Hp-Htt) have been examined using the anti-Hp-Htt antibody (Ab) raised against synthetic oligopeptides. According to immunoblotting, Hp-Htt was detected as a single band at around the 350 kDa region at the swimming blastula stage to the prism larva stage. From the 2-arm pluteus stage (2aPL), however, an additional smaller band at the 165 kDa region appeared. Immunohistochemically, Hp-Htt was detected in the nuclei and the nearby cytoplasm of the ectodermal cells from the swimming blastula stage, and the blastocoelar cells from the mid-gastrula stage. The Ab-positive signal was converged to the ciliary band-associated strand (CBAS). There, it was accompanied by several CBAS-marker proteins in the cytoplasm, such as glutamate decarboxylase. Application of Hp-Htt morpholino (Hp-Htt-MO) has resulted in shortened larval arms, accompanied by decreased 5-bromo-2-deoxyuridin (BrdU) incorporation by the ectodermal cells of the larval arms. Hp-Htt-MO also resulted in lowered ciliary beating activity, accompanied by a disordered swirling pattern formation around the body. These Hp-Htt-MO-induced deficiencies took place after the onset of CBAS system formation at the larval arms. Thus, Hp-Htt is involved in cell proliferation and the ciliary beating pattern regulation signaling system in pluteus larvae.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

Tension at the Surface of Sea-Urchin Egg: A Critical Examination of Cole's Experiment

1964 ◽  
Vol 41 (4) ◽  
pp. 893-906 ◽  
Author(s):  
MITSUKI YONEDA
Keyword(s):  
Surface Area ◽  
Sea Urchin ◽  
Contact Area ◽  
Surface Force ◽  
Critical Examination ◽  
Compression Method ◽  
Osmotic Swelling ◽  
Technical Errors ◽  
Sea Urchin Egg ◽  
Hemicentrotus Pulcherrimus

1. The compression method for calculating the surface force of the sea-urchin egg, developed by Cole (1932), has been critically repeated using unfertilized eggs of Hemicentrotus pulcherrimus. 2. Estimation of contact area involved in Cole's equation introduces technical errors. 3. The tension recalculated by another equation including surface area as a parameter is found to remain constant irrespective of change in surface area. This is in conflict with the classical belief that the cortex of the egg of sea urchin is elastic. 4. Neither osmotic swelling nor osmotic shrinkage of the egg affects the tension.

Inhibition of the development of pulmonary tumour nodules and stimulation of the activity of NK cells and macrophages in mice by single low doses of low-LET radiation

2004 ◽  
Vol 1 (2) ◽  
pp. 171 ◽  
Author(s):  
A. Cheda ◽  
J. Wrembel-Wargocka ◽  
E. Lisiak ◽  
M. Marciniak ◽  
E. Nowosielska ◽  
...  
Keyword(s):  
Nk Cells ◽  
Low Doses ◽  
Stimulation Of

scholarly journals Multifaceted action of Fuzeon as virus–cell membrane fusion inhibitor

2011 ◽  
Vol 1808 (10) ◽  
pp. 2352-2358 ◽  
Author(s):  
Avraham Ashkenazi ◽  
Yael Wexler-Cohen ◽  
Yechiel Shai
Keyword(s):  
Cell Membrane ◽  
Membrane Fusion ◽  
Fusion Inhibitor
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