Structure and function of asterosaps, sperm-activating peptides from the jelly coat of starfish eggs

Zygote ◽  
1996 ◽  
Vol 4 (3) ◽  
pp. 237-245 ◽  
Author(s):  
Takuya Nishigaki ◽  
Kazuyoshi Chiba ◽  
Wataru Miki ◽  
Motonori Hoshi
Keyword(s):  
Acrosome Reaction ◽  
Physiological Role ◽  
Structural Diversity ◽  
Asterias Amurensis ◽  
Amino Terminal ◽  
Jelly Coat ◽  
Ionisation Mass Spectrometry ◽  
Egg Jelly ◽  
And Function

SummaryJelly coat of starfish eggs has the capacity to activate homologous spermatozoa and induce the acrosome reaction. We have isolated 12 sperm-activating peptides (SAPs) from the egg jelly of the starfish, Asterias amurensis. Eleven SAPs were structurally identified by sequence analysis and electro-spray ionisation mass spectrometry. All of them are glutamine-rich tetratriacontapeptides with an intramolecular disulphide linkage between Cys8 and Cys32. They are much larger than sea urchin SAPs and do not show any significant sequence similarities to known proteins. Thus we have collectively named them asterosaps. The amino terminal region, where structural diversity of asterosaps is observed, is not important for their activity, whereas the disulphide linkage is essential. Asterosaps do not induce the acrosome reaction by themselves, but are able to induce the acrosome reaction in combination with an egg jelly glycoconjugate named ARIS. Furthermore, anti-asterosap rabbit antibody significantly decreased the acrosome reaction-inducing activity of the jelly solution and the activity was restored by addition of excess asterosap. These results support our hypothesis that the main physiological role of SAPs is the induction of the acrosome reaction in cooperation with two other jelly components, ARIS and Co-ARIS.

A critical physiological role of zinc in the structure and function of biomembranes

Life Sciences ◽  
1981 ◽  
Vol 28 (13) ◽  
pp. 1425-1438 ◽  
Author(s):  
William J. Bettger ◽  
Boyd L. O'Dell
Keyword(s):  
Physiological Role ◽  
Structure And Function ◽  
And Function

Cytochalasin B does not block sperm penetration into denuded starfish oocytes

Zygote ◽  
1994 ◽  
Vol 2 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Keiichiro Kyozuka ◽  
Kenzi Osanai
Keyword(s):  
Plasma Membrane ◽  
Actin Filament ◽  
Cytochalasin B ◽  
Sperm Head ◽  
Asterias Amurensis ◽  
Jelly Coat ◽  
Dense Cytoplasm ◽  
Sperm Penetration ◽  
Vitelline Coat

SummaryDuring fertilisation in starfish oocytes, the fertilisation cone develops temporarily beneath the penetrating sperm. The role of the fertilisation cone in sperm incorporation in the starfish Asterias amurensis was examined using cytochalasin B (CB). CB (2 μM) allowed sperm acrosomal process–egg plasma membrane fusion and egg activation, but inhibited the development of the fertilisation cone containing actin microfilaments. When sperm were added to intact oocytes (with the jelly coat and vitelline coat) in seawater containing CB, the sperm head did not penetrate the fertilisation membrane. Although the acrosomal process fused with egg plasma membrane, the sperm head remained outside the fertilisation membrane. On the other hand, denuded oocytes without the jelly coat and vitelline coat allowed sperm penetration even in the presence of 2 μM CB. Electron microscopy revealed that sperm organelles, including the acrosomal process, nucleus, mitochondrion and tail, were incorporated into the slightly electron-dense cytoplasm, which was similar to the cytoplasm of the fertilisation cone. These results show that the development of the fertilisation cone/actin filament complex is not essential for incorporation of the sperm, since incorporation can occur in denuded oocytes. However, the cone is required for fertilisation of intact oocytes, suggesting that this actin-filament-containing structure is necessary for getting the sperm through the outer egg coats.

scholarly journals Ca2+ signaling evoked by activation of Na+ channels and Na+/Ca2+ exchangers is required for GABA-induced NG2 cell migration

2009 ◽  
Vol 186 (1) ◽  
pp. 113-128 ◽  
Author(s):  
Xiao-ping Tong ◽  
Xiang-yao Li ◽  
Bing Zhou ◽  
Wanhua Shen ◽  
Zhi-jun Zhang ◽  
...  
Keyword(s):  
Gabaa Receptors ◽  
Physiological Role ◽  
Brain Regions ◽  
Na Channels ◽  
Typical Action ◽  
Sequential Activation ◽  
Ng2 Cells ◽  
And Function ◽  
Ca2 Channels

NG2 cells originate from various brain regions and migrate to their destinations during early development. These cells express voltage-gated Na+ channels but fail to produce typical action potentials. The physiological role of Na+ channels in these cells is unclear. We found that GABA induces membrane depolarization and Ca2+ elevation in NG2 cells, a process requiring activation of GABAA receptors, Na+ channels, and Na+/Ca2+ exchangers (NCXs), but not Ca2+ channels. We have identified a persistent Na+ current in these cells that may underlie the GABA-induced pathway of prolonged Na+ elevation, which in turn triggers Ca2+ influx via NCXs. This unique Ca2+ signaling pathway is further shown to be involved in the migration of NG2 cells. Thus, GABAergic signaling mediated by sequential activation of GABAA receptors, noninactivating Na+ channels, and NCXs may play an important role in the development and function of NG2 glial cells in the brain.

scholarly journals Structure of acrosome reaction-inducing steroidal saponins from the egg jelly of the starfish, Asterias amurensis.

1987 ◽  
Vol 35 (5) ◽  
pp. 1829-1832 ◽  
Author(s):  
YOSHINORI FUJIMOTO ◽  
TAKETOSHI YAMADA ◽  
NOBUO IKEKAWA ◽  
ICHIRO NISHIYAMA ◽  
TAEI MATSUI ◽  
...  
Keyword(s):  
Acrosome Reaction ◽  
Steroidal Saponins ◽  
Asterias Amurensis ◽  
Egg Jelly

scholarly journals Mice Deficient in the Axonemal Protein Tektin-t Exhibit Male Infertility and Immotile-Cilium Syndrome Due to Impaired Inner Arm Dynein Function

2004 ◽  
Vol 24 (18) ◽  
pp. 7958-7964 ◽  
Author(s):  
Hiromitsu Tanaka ◽  
Naoko Iguchi ◽  
Yoshiro Toyama ◽  
Kouichi Kitamura ◽  
Tohru Takahashi ◽  
...  
Keyword(s):  
Physiological Role ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Vitro Fertilization ◽  
Homozygous Mutant ◽  
Causal Genes ◽  
And Function ◽  
Ciliary Dyskinesia

ABSTRACT The haploid germ cell-specific Tektin-t protein is a member of the Tektin family of proteins that form filaments in flagellar, ciliary, and axonemal microtubules. To investigate the physiological role of Tektin-t, we generated mice with a mutation in the tektin-t gene. The homozygous mutant males were infertile, while the females were fully fertile. Sperm morphology and function were abnormal, with frequent bending of the sperm flagella and marked defects in motility. In vitro fertilization assays showed that the defective spermatozoa were able to fertilize eggs. Electron microscopic examination showed that the dynein inner arm structure was disrupted in the sperm flagella of tektin-t-deficient mice. Furthermore, homozygous mutant mice had functionally defective tracheal cilia, as evidenced by altered dynein arm morphology. These results indicate that Tektin-t participates in dynein inner arm formation or attachment and that the loss of Tektin-t results in impaired motility of both flagella and cilia. Therefore, the tektin-t gene is one of the causal genes for immotile-cilium syndrome/primary ciliary dyskinesia.

Asterosap-induced elevation in intracellular pH is indispensable for ARIS-induced sustained increase in intracellular Ca2+ and following acrosome reaction in starfish spermatozoa

Zygote ◽  
2005 ◽  
Vol 13 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Osamu Kawase ◽  
Hiroyuki Minakata ◽  
Motonori Hoshi ◽  
Midori Matsumoto
Keyword(s):  
Intracellular Ph ◽  
Acrosome Reaction ◽  
Slight Reduction ◽  
Asterias Amurensis ◽  
High Ph ◽  
Egg Jelly ◽  
Sustained Increase ◽  
Three Components

In the starfish, Asterias amurensis, the cooperation of three components of the egg jelly, namely ARIS (acrosome reaction-inducing substance), Co-ARIS and asterosap, is responsible for the induction of acrosome reaction. For the induction, ARIS alone is enough in high-Ca2+ or high-pH seawater, but, besides ARIS, the addition of either Co-ARIS or asterosap is required in normal seawater. Asterosap transiently increased both the intracellular pH (pHi) and Ca2+ ([Ca2+]i), while ARIS slightly elevated the basal level of [Ca2+]i. However, a sustained elevation of [Ca2+]i and acrosome reaction occurred if sperm were simultaneously treated with ARIS and asterosap. EGTA inhibited the sustained [Ca2+]i elevation and acrosome reaction. The sustained [Ca2+]i elevation and acrosome reaction were highly susceptible to SKF96365 and Ni2+, specific blockers of the store-operated Ca2+ channel (SOC). These results suggest that sustained [Ca2+]i elevation, mediated by the SOC-like channel, is a prerequisite for the acrosome reaction. In high-pH seawater, ARIS alone induced a prominent [Ca2+]i increase and acrosome reaction, which were similarly sensitive to SKF96365. The acrosome reaction was effectively induced by ARIS alone when pHi was artificially increased to more than 7.7. Asterosap increased pHi from 7.6±0.1 to 7.7±0.1. Furthermore, the sustained [Ca2+]i elevation and acrosome reaction, induced by a combination of ARIS and asterosap, were drastically inhibited by a slight reduction in pHi. Taking these results into account, we suggest that an asterosap-induced pHi elevation is required for triggering the ARIS-induced sustained [Ca2+]i elevation and consequent acrosome reaction.

Structures of the sugar chains of a major glycoprotein present in the egg jelly coat of a starfish, Asterias amurensis

1987 ◽  
Vol 252 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Tamao Endo ◽  
Motonori Hoshi ◽  
Satoshi Endo ◽  
Yoji Arata ◽  
Akira Kobata
Keyword(s):  
Asterias Amurensis ◽  
Jelly Coat ◽  
Egg Jelly ◽  
Sugar Chains

Estimation by radiation inactivation of the minimum functional size of acrosome-reaction-including substance (ARIS) in the starfish, Asterias amurensis

Zygote ◽  
1995 ◽  
Vol 3 (4) ◽  
pp. 351-355 ◽  
Author(s):  
Akira Ushiyama ◽  
Kazuyoshi Chiba ◽  
Akihiro Shima ◽  
Motonori Hoshi
Keyword(s):  
Acrosome Reaction ◽  
Functional Unit ◽  
Sugar Content ◽  
High Energy ◽  
Target Size ◽  
Minimum Size ◽  
Size Analysis ◽  
Asterias Amurensis ◽  
Total Sugar Content ◽  
Jelly Coat

SummaryIn the starfish Asterias amurensis, the jelly coat of the eggs contains a glycoprotein essential for the induction of the acrosome reaction in homologous spermatozoa that is termed the acrosome-reaction-inducing substance (ARIS).ARIS is a highly sulphated and fucose-rich glycoprotein of extremely high molecular mass(>104 kDa). ARIS was irradiated with high-energy eletrons in order to estimate the minimum size required for its biological activity. The minimum functional unit or target size of ARIS was estimated to be c. 14 kDa by target size analysis. ARIS was significantly disintegrated by the irradiation, yet the total sugar content was not apparently reduced. The binding of 125I-labelled ARIS to spermatozoa competed with that of irradiated ARIS, although the affinity of ARIS was much reduced after irradiation.

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