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1.
Urea is an effective reagent for inducing the acrosome reaction of spermatozoa in sea urchins. Urea-treated spermatozoa are capable of fertilizing eggs in Ca-deficient sea water. The pH of the urea solution is an important factor affecting the induction of the acrosome reaction. The reaction occurs at a high percentage in urea Solution at pH's higher than 7.8, while the reaction is almost completely suppressed at pH 7.2. Ca++ is also an important factor for the induction of the reaction, although the minimum concentration required is very low.
The acrosomal filament formed in urea solution is similar in shape to that formed in egg-water, when fixed after 10 seconds' urea-treatment. The acrosome granule material is found around the basal portion of the acrosomal filament. 相似文献
The acrosomal filament formed in urea solution is similar in shape to that formed in egg-water, when fixed after 10 seconds' urea-treatment. The acrosome granule material is found around the basal portion of the acrosomal filament. 相似文献
2.
Biochemical Studies on the Acrosome Reaction of the Starfish, Asterias Amurensis I. Factors Participating in the Acrosome Reaction 总被引:3,自引:3,他引:0
In contrast with the case in sea urchin sperm, in starfish the acrosome reaction is not spontaneously induced by simply increasing the extracellular Ca2+ concentration or pH. At higher pHs, starfish sperm undergo morphological changes accompanied by exocytosis of the acrosomal vacuole, but they do not form acrosomal filaments. Nomarski-microscopic observation confirmed that spermatozoa undergo the acrosome reaction within the jelly coat. Acrosome reaction-inducing substance, a glycoprotein from the egg jelly, required a diffusible cofactor(s) present in the egg jelly for full activity. Several lines of evidence showed that this diffusible factor(s) is not merely Ca2+ . 相似文献
3.
We examined whether phospholipase A2 (PLA2 ) is involved in the initiation of the acrosome reaction of sperm of the sea urchin, Strongylocentrotus intermedius , using inhibitors and an activator of this enzyme. Quinacrine and p-bromophenacyl bromide (PBPB) inhibited the egg jelly-induced acrosome reaction at 100 μM, but not the ionomycin-induced one. Depression of egg jelly-induced increase of intracellular free Ca2+ concentration ([Ca2+ ]i ) by these reagents was expected and examined using fura 2. Quinacrine interfered with the flourescence of fura 2, but PBPB was found to depress at concentrations which could inhibit the acrosome reaction. Furthermore, melittin, which is known to stimulate PLA2 , caused a [Ca2+ ]i increase and a formation of acrosomal process-like structure on sperm head. These results suggest that PLA2 participates in the early step(s) of the acrosome reaction of sea urchin sperm. 相似文献
4.
ICHIRO NISHIYAMA HAJIME SASAKI TAEI MATSUI MOTONORI HOSHI 《Development, growth & differentiation》1985,27(4):461-468
Two types of anion channel blockers, SITS (4-acetamide-4'-isothiocyanostilbene-2,2'-disulfonic acid) and DIDS (4,4'-diisothiocyanostilbene-2, 2'-disulfonic acid), inhibited jelly-induced acrosorne reaction in starfish and sea urchin. In starfish sperm, both of the blockers reversibly inhibited the formation of acrosomal process but they had no effect on either the acrosomal exocytosis or acid release from the sperm. Complete acrosome reaction occurred even in Cl− - and SO4 2− -free artificial seawater whereas HCO3 − was required for the acrosomal exocytosis. Importance of anion transport in acrosome reaction is discussed. 相似文献
5.
KAORI MIKAMI-TAKEI AKIKO FUJIWARA IKUO YASUMASU 《Development, growth & differentiation》1988,30(2):125-135
The acrosome reaction in sea urchin sperm, as judged by disappearance of the acrosomal vesicles in Nomarski optics, was induced by dimethylsulfoxide (DMSO) at concentration above 0.1% in normal artificial sea water. The number of the acrosome-reacted spermatozoa increased in proportion to DMSO concentration. The DMSO-induced acrosome reaction, as well as the jelly water- or A23187-induced one, was inhibited by nifedipine and hardly occurred in Ca2+ -free artificial sea water. However, the DMSO-induced acrosome reaction was found in a few number of spermatozoa in the presence of Ca2+ at above 0.5 mM, though the jelly water- or A23187-induced acrosome reaction did not occur at external Ca2+ levels lower than 1 mM. Dependency of the acrosome reaction by DMSO on external Ca2+ is somewhat lower than that of the reaction by jelly water. In Ca2+ -free artificial sea water, the acrosomal regions of DMSO-treated spermatozoa attached to their own tails. In some cases, spermatozoa thus treated with DMSO in Ca2+ free artificial sea water caused formation of fertilization membrane in a few number of eggs kept in Ca2+ -free artificial sea water. Even in the absence of extermal Ca2+ , preliminary step of the acrosome reaction seems to be completed probably by DMSO-induced weak Ca2+ -mobilization in spermatozoa. 相似文献
6.
The lectin wheat germ agglutinin (WGA) inhibited the egg jelly-induced acrosome reaction (AR) of sperm of the sea urchin, Strongylocentrotus intermedius . Fluorescein-conjugated WGA applied to sperm bound to the acrosomal region, to the midpiece, and to the tip of the flagellum. These effects were not observed in the presence of N-acetly-D-glucosamine. When the egg jelly was replaced by artificial AR inducers such as A23187 or nigericin, the AR was not inhibited by WGA. Results obtained using a Ca2+ indicator fura-2, a pH indicator 2',7'-bis(carboxyethyl)carboxyfluorescein (BCECF) and a membrane potential sensitive dye 3,3'-dipentyl 2,2'-dioxacarbocyanine [diO-C5 (3)] showed that WGA suppresses the egg jelly-induced influx of Ca2+ and slightly suppresses the efflux of H+ caused by the egg jelly, whereas the depolarization of the plasma membrane by the egg jelly is remarkably amplified by the treatment with WGA. These results suggest that WGA affects the regulatory system of the ion fluxes associated with the AR. The target protein of WGA (WGA-binding protein) was a membrane glycoprotein of 260 kD under non-reducing condition. 相似文献
7.
Sensing DNA damage and initiation of genetic responses to repair DNA damage are critical to cell survival. In Escherichia coli , RecA polymerizes on ssDNA produced by DNA damage creating a RecA–DNA filament that interacts with the LexA repressor inducing the SOS response. RecA filament stability is negatively modulated by RecX and UvrD. recA730 (E38K) and recA4142 (F217Y) constitutively express the SOS response. recA4162 (I298V) and recA4164 (L126V) are intragenic suppressors of the constitutive SOS phenotype of recA730 . Herein, it is shown that these suppressors are not allele specific and can suppress SOSC expression of recA730 and recA4142 in cis and in trans . recA4162 and recA4164 single mutants (and the recA730 and recA4142 derivatives) are Rec+ , UVR and are able to induce the SOS response after UV treatment like wild-type. UvrD and RecX are required for the suppression in two ( recA730,4164 and recA4142,4162 ) of the four double mutants tested. To explain the data, one model suggests that recA C alleles promote SOSC expression by mimicking RecA filament structures that induce SOS and the suppressor alleles mimic RecA filament at end of SOS. UvrD and RecX are attracted to these latter structures to help dismantle or destabilize the RecA filament. 相似文献
8.
Barry J. M. Gibb Janice Robertson Christopher C. J. Miller 《Journal of neurochemistry》1996,66(3):1306-1311
Abstract: Ser55 within the head domain of neurofilament light chain (NF-L) is transiently phosphorylated by protein kinase A, and phosphorylation of this residue is thought to regulate assembly of neurofilaments. To understand how Ser55 phosphorylation influences NF-L assembly, wild-type and mutant NF-L genes in which Ser55 was mutated to alanine, so as to prevent phosphorylation, or to aspartate, so as to mimic permanent phosphorylation, were transfected into mammalian cells that contain or do not contain an endogenous intermediate filament network. Wild-type and mutant NF-Ls localised to the Triton X-100-insoluble fraction, which suggests that phosphorylation of Ser55 does not inhibit assembly of NF-L and NF-L/vimentin polymers at or below the tetrameric stage. Immunofluorescence microscopy of transfected cells demonstrated that the wild-type and mutant NF-Ls all colocalised with vimentin to produce similar filamentous arrays. However, in cells lacking an endogenous intermediate filament network, the aspartate mutant produced a pattern of staining different from that of the wild-type or alanine mutant. These results suggest that phosphorylation of NF-L Ser55 is not a mechanism that precludes assembly of neurofilaments from monomers into intermediate filament structures but that phosphorylation/dephosphorylation of this residue might confer more subtle characteristics on neurofilament assembly properties and architecture. 相似文献
9.
Requirement of Extracellular Calcium Ions for the Early Fertilization Events in the Medaka Egg 总被引:1,自引:1,他引:0
The requirement for calcium and the change in calcium content in eggs of Oryzias iatipes during the cortical reaction and sperm penetration were examined. Naked eggs failed to exhibit the cortical reaction upon insemination under Ca Mg-free conditions. These eggs exhibited the cortical reaction by reinsemination in the presence of extracellular Ca2+ . The effect of extracellular Ca2+ on sperm penetration could be replaced by one of several divalent cations in the external medium. Unlike the cortical reaction, sperm penetration failed to be induced by microinjection to increase intracellular Ca2+ . Verapamil significantly reduced the action of extracellular Ca2+ or Ba2+ of divalent cations examined in fertilization, while TEA and TTX had no effect on fertilization in the presence of these cations. No 45 Ca uptake into the egg proper was recognized before completion of the cortical reaction. These observations suggest that extracellular divalent cations are indispensable for sperm stimulation of the egg and its penetration into the egg, for which an influx of Ca2+ from the external medium is not required. 相似文献
10.
Effects of Cations and Other Medium Components on the Zona-induced Acrosome Reaction of Hamster Spermatozoa 总被引:1,自引:0,他引:1
Although the acrosome reaction in lively motile hamster spermatozoa can occur independently of the egg or its investments ("spontaneous" acrosome reaction), it appears to be the egg investments, particularly the zona pellucida, that induces the acrosome reaction in fertilizing spermatozoa of many mammalian species. The latter is referred to as "zona-induced" acrosome reaction. Experiments were conducted to determine if the zona-induced acrosome reaction has different ion requirements from the spontaneous reaction. Like the spontaneous acrosome reaction, the zona-induced acrosome reaction required extracellular Na+ , K+ and Ca2+ . The absence of Cl− and albumin in the medium inhibited the reaction. The zona-induced acrosome reaction could occur in a HCO3 − -free medium, but far less efficiently than in medium containing this ion. Proteinase inhibitors, benzamidine and TLCK, inhibited the zona-induced acrosome reaction. These results suggest that the chemical reactions involved in the spontaneous and zona-induced acrosome reactions are similar although the reaction-triggering mechanism is probably different. 相似文献
11.
The reductive carboxylation of α-ketoglutarate by purified NADP+ -isocitrate dehydrogenase (EC 1.1.1.42) from maturing castor bean seeds ( Ricinus communis L. ) has been characterized. The optimum pH for the reaction was 6.5, whereas pH 8.5 was optimum for oxidation of isocitrate (forward reaction). The enzyme utilized NADH as well as NADPH as the reducing agent in the reverse reaction, but only NADP+ in the forward reaction. The Km values for NADPH and NADH were 0.044 and 2.8 m M respectively, and for α-ketoglutarate and HCO3 4.1 and 3.7 m M. The enzyme was activated by various cations including Mg2+ , Mn2+ , Co2+ , Zn2+ , Ni2+ and Co2+ . Km values for Mg2+ Mn2+ , Co2+ and Zn2+ were 12, 34, 37 and 49μ M respectively. 相似文献
12.
A. C. W. Utne 《Journal of fish biology》1997,50(5):926-938
Both reduced illumination and increased turbidity caused a significant reduction in reaction distance of Gobiusculus flavescens . The longest reaction distance, 18.9 cm for larger prey (Calanus finmarchicus) , occurred at a light level of 80 μmol m −2 s −1 compared to 12.9 cm for a smaller prey (Acartia clausi) at 8 μmol m−2 s−1 . Above a light saturation level of 10 μmol m−2 s−1 , additional light had little influence on reaction distance. In the turbidity experiments, the longest reaction distances were measured at turbidity levels of 10–20 JTU. Prey size influenced reaction distance at all tested light levels. Search time was influenced by prey size only at low illumination. With increasing turbidity, reaction distance to a group of prey was longer than to one prey. 相似文献
13.
Tosikazu Amano Yoshihito Okita Motonori Hoshi 《Development, growth & differentiation》1993,35(5):521-529
Egg jelly induces the degradation of histones as well as the acrosome reaction in the spermatozoa of Asterina pectinifera . Much similar degradation of histones without any apparent morphological changes such as the acrosome reaction was induced in the spermatozoa by merely dispersing them into Na+ -free seawater. It required external Ca2+ much less than the jelly-induced one in normal seawater, and was not susceptible to Ca2+ -channel antagonists, verapamil and diltiazem. Once spermatozoa were incubated with egg jelly in Ca2+ -free seawater, they did not undergo the histone degradation even after subsequent addition of Ca2+ , but Na+ -free seawater rescued such blockage. Spontaneous acrosome reaction occurred in seawater containing 10–30 mM Na+ in a Ca2+ -dependent manner. This reaction was accompanied by a rapid increase in intracellular pH (pHi) followed by a large pHi decrease. Diltiazem blocked a large decrease in pHi but scarcely inhibited the acrosome reaction induced by low-Na+ seawater. Increasing K+ inhibited both pHi changes and the acrosome reaction induced by low-Na+ seawater. Decreasing pH of seawater also inhibited the pHi changes but did not affect the acrosome reaction. Strontium was also effective to induce a rapid increase, followed by a gradual decrease, in pHi and the acrosome reaction. 相似文献
14.
Miho Takahashi Kayoko Tomizawa Koichi Ishiguro Masako Takamatsu Shinobu C. Fujita Kazutomo Imahori 《Journal of neurochemistry》1995,64(4):1759-1768
Abstract: τ protein kinase I (TPKI) phosphorylates τ and forms paired helical filament epitopes in vitro. We studied temporal expression and histochemical distribution of τ phosphoserine epitopes at sites known to be phosphorylated by TPKI. Antibodies directed against phosphorylated Ser199 (anti-PS 199) or phosphorylated Ser396 (C5 or anti-PS 396) were used. TPKI is abundantly expressed in the young rat brain and the highly phosphorylated juvenile form of τ occurs in the same period. The activity peak of TPKI coincided with the high level of phosphorylation of Ser199 and Ser396 in juvenile τ at around postnatal day 8. By immunohistochemistry on the hippocampus and neocortex of 3–11-day-old rats, phosphorylated Ser396 was found in young axonal tracts and neuropil, where TPKI immunoreactivity was also detected. TPKI and phospho-Ser199 immunoreactivities were also detected in the perikarya of pyramidal neurons. TPKI immunoreactivity had declined to a low level and phosphorylated serine immunoreactivities were undetectable in the sections of adult brain. These findings implicate TPKI in paired helical filament-like phosphorylation of juvenile form of τ in the developing brain. 相似文献
15.
Abstract— Calcium is transported at a fast rate of 410 mm/day in cat sciatic nerve on injection of 45 Ca2+ into the L7 dorsal root ganglia. Nerve segments corresponding to the crest and the plateau regions of transported activity were analyzed by column chromatography on Sephadex G-100 and Biogel A 5m columns and the fast transported 45 Ca2+ found to be bound to a protein of 15,000 dalton. Using [3 H]leucine as a precursor, a labeled calcium binding protein (CaBP) was found located at the same position in elution volumes from the columns as was the protein-bound 45 Ca2 + . The level of [3 H]-labeled CaBP in the crest and plateau regions were compared using column chromatography and polyacrylamide gel electrophoresis techniques and approx 3×4 times more [3 H]-labeled activity was found in the crest as compared to the plateau. These findings indicate that Ca2+ is fast transported in association with the CaBP. The relation of CaBP to the transport filament model of axoplasmic transport and its possible role in nerve are discussed. 相似文献
16.
Keiko Mitsunaga Akiko Fujiwara Yukio Fujino Ikuo Yasumasu 《Development, growth & differentiation》1989,31(2):171-178
In cultured cells derived from micromeres isolated at the 16-cell stage of sea urchin embryos, the activity of H+ , K+ -ATPase became detectable after 15 hr of culture, when the cells started to form spicules, and then increased reaching a plateau from 25 hr of culture. The Na+ , K+ -ATPase activity of isolated micromeres increased to a maximum at 20 hr of culture and thereafter decreased gradually. Allylisothiocyanate, an inhibitor of H+ , K+ -ATPase, caused a decrease in intracellular pH (pHi) accompanied by blockage of 45 Ca deposition in spicule rods in spicule-forming cells at 30 hr of culture. Ouabain and amiloride had scarcely any effect on the pHi or 45 , deposition. In cultured cells exposed to nifedipine, which blocked 45 Ca deposition in spicule rods, allylisothiocyanate did not cause any decrease in pHi. These results show that H+ , which is generated in the overall reaction to produce CaCO3 from Ca2+ and HCO3 − , is probably released from the cells mainly in the reaction catalyzed by H+ , K+ -ATPase to maintain successive production of CaCO3 . 相似文献
17.
NADP+ -malic enzyme ( l -malate: NADP+ oxidoreductase, decarboxylating EC 1.1.1.40) from pod walls of chickpea was purified 51-fold by ammonium sulphate fractionation, DEAE- cellulose chromatography and gel filtration through Sepharose 4B. The purified enzyme required a divalent cation, either Mn2+ or Mg2+ , for its activity. Km values at pH 7.8 for malate, NADP+ and Mn2+ were 4.0, 0.031 and 0.71 m M , respectively. Mn2+ -dependent activity was inhibited by heavy metal ions such as Cd2+ , Zn2+ , Hg2+ , and to a lesser extent by Pb2+ and Al3+ . Among the organic acids examined, sodium salts of oxalate and oxaloacetate were inhibitory. Kinetics of the reaction mechanism showed sequential binding of malate and NADP+ to the enzyme. Products of reaction, viz. pyruvate, bicarbonate and NADPH, inhibited the enzyme activity. At limiting concentrations of NADP+ , pyruvate and bicarbonate induced a positive cooperative effect by malate. It is proposed that the activity of NADP+ -malic enzyme is controlled by intracellular concentrations of substrates and products. 相似文献
18.
Induction of the Acrosome Reaction in Starfish 总被引:7,自引:6,他引:1
TAEI MATSUI ICHIRO NISHIYAMA AKIYA HINO MOTONORI HOSHI 《Development, growth & differentiation》1986,28(4):339-348
In the starfish, Asterias amurensis , at least two distinct components of the egg jelly are required for inducing the acrosome reaction: a sulfated glycoprotein named acrosome reaction-inducing substance (ARIS) and a diffusible organic substance(s) named Co-ARIS. The following evidence suggested that ARIS and Co-ARIS cooperatively activate CA-channels of the sperm plasma membrane and eventually induce dramatic changes in sperm morphology, the acrosome reaction. 1) Pronase digest of ARIS (P-ARIS) and Co-ARIS, either as a pure or a crude preparation (Fraction M8 ), were fully effective in combination for induction of the acrosome reaction in normal sea water, although they were not effective individually. P- ARIS alone induced the acrosome reaction fully in high Ca2+ sea water and markedly at high pHs, whereas Fraction M8 alone did not induce the reaction even in these conditions. The reaction was not induced by increase in either the Ca2+ concentration or the pH of sea water, but was markedly induced in the absence of jelly components by raising both the pH and Ca2+ concentration together. 2) The ionophore A23187 induced the acrosome reaction appreciably when present alone and fully in the presence of monensin or Fraction M8 . Monesin alone was ineffective. 3) The jelly or a combination of ARIS and Fraction M8 caused abrupt Ca2+ -uptake by the sperm. The Ca-channel blockers verapamil and diltiazem inhibited the jelly-induced acrosome reaction. 相似文献
19.
Yasuhiro Iwao Akiko Miki Michiko Kobayashi Kazuo Onitake 《Development, growth & differentiation》1994,36(5):469-479
An extract obtained from Cynops sperm induced the activation of both Cynops and Xenopus eggs with accompanying changes in the potential of the egg membrane that were quite similar to those caused by the Cynops sperm. The activation-inducing properties of the extract were abolished by treatment with proteinase K or by heating (60°C, 15 min) and were associated with a protease activity against peptidyl Arg-MCA substrates. The activation of Xenopus eggs by the extract was inhibited by those substrates, or by protease inhibitors, aprotinin or leupeptin. The protease activity was localized in the acrosomal region of Cynops sperm. The activation of Xenopus eggs by the extract was prevented when the exterior concentration of Ca2+ ions, [Ca2+ ]0 , was reduced to 1.5 μM, but it was enhanced when [Ca2+ ]0 was increased to 340 μM. The activation of Xenopus eggs by the extract was not affected by positive clamping when [Ca2+ ]0 was 340 μM. These results suggest that the sperm extract contains a protease that causes an increase in the influx of Ca2+ ions that results in voltage-insensitive activation of the egg. 相似文献
20.
YUKIO FUJINO KEIKO MITSUNAGA IKUO YASUMASU 《Development, growth & differentiation》1987,29(6):591-597
Embryos kept with omeprazole, a specific H+ , K+ -ATPase inhibitor, in a period of development between the mesenchyme blastula and the pluteus corresponding stage became abnormal plutei having quite small spicules, somewhat poor pluteus arms and apparently normal archenterons. In micro-mere-derived cells, kept with omeprazole at pH 8.2 in a period between 15 and 40 hr of culture at 20°C, omeprazole strongly inhibited spicule formation but did not block the outgrowth of pseudopodial cables, in which spicule rods were to be formed. These indicate that omeprazole probably exerts no obvious inhibitory effects other than spicule rods formation. Omeprazole-sensitive H+ , K+ -ATPase, an H+ pump, seems to be indispensable for CaCO3 deposition (formation of spicule rod) in these spicule forming cells. H+ , produced in overall reaction for CaCO3 formation: Ca2+ + CO2 +H2 O°CaCO3 +2H+ , is probably released from the cells by this H+ pump and hence, this reaction tends to go to CaCO3 production to form spicule rods. Omeprazole, known to become effective following its conversion to a specific inhibitor of H+ , K+ -ATPase at acidic pH, is able to inhibit formation of spicule rod at alkaline pH in sea water. This is probably due to an acidification of sea water near the cell surface by H+ ejection in H+ , K+ -ATPase reaction. 相似文献