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31.
HITOSHI OKUMOTO MIDORI NISHIOKA IKUO MIURA MASATAKA OBIKA 《Pigment cell & melanoma research》1995,8(4):187-193
A cDNA encoding tyrosinase of Rana nigromaculata was introduced into cultured, tyrosinase-negative amelanotic melanophores of R. brevipoda by a calcium phosphate precipitation method. Within a few days following transfection, dark pigmentation became visible in a small number of cells. Light microscopic observation revealed that the morphology of these transformed cells was comparable to that of normal melanophores in culture, and their proliferative activity was lower than that of amelanotic cells. Ultrastructural examination verified that amelanotic melanophores possessed a relatively small number of premelanosomes while the transformants contained numerous melanosomes at various stages of pigment deposition. The result indicated that tyrosinase cDNA of R. nigromaculata was expressed in amelanotic melanophores of R. brevipoda inducing the maturation of premelanosomes. It was also suggested that the expression of transfected tyrosinase cDNA had promoted differentiation of the amelanotic cells into fully developed melanophores. 相似文献
32.
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
33.
Respiration of Sea Urchin Spermatozoa in the Presence of a Synthetic Jelly Coat Peptide and Ionophores 总被引:1,自引:1,他引:0
NORIO SUZUKI YASUSHI OHIZUMI IKUO YASUMASU SABRO ISAKA 《Development, growth & differentiation》1984,26(1):17-24
Sperm respiration and motility of the sea urchin Hemicentrotus pulcherrimus were studied at pH 6.8 in the presence of a synthetic jelly peptide (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly) and monovalent cationic ionophores. The synthetic peptide stimulated sperm respiration and motility to the level of that found in normal sea water (pH 8.2) with half-maximal stimulation at approximately 100 pM. Monensin and valinomycin also stimulated sperm respiration with half-maximal effects at 7 μM and 0.7 μM, respectively. The stimulation of sperm respiration by the peptide and monensin was dependent on external Na+ , but was not dependent on the osmolarity of the suspending medium. Approximately 50 mM Na+ was required for half-maximal respiratory responses to the peptide and monensin. 相似文献
34.
YUKIO FUJINO KEIKO MITSUNAGA IKUO YASUMASU 《Development, growth & differentiation》1987,29(6):599-605
In artificial sea water in which the Cl− concentration was reduced to less than 10% of that in normal sea water by its replacement with Br− , sea urchin eggs were fertilized and developed into abnormal plutei following almost the same time schedule as in natural sea water. These embryos had poorly developed spicules, short pluteus arms, somewhat jagged embryo-walls and quasi-normal archenterons. Similar embryos were obtained in another artificial sea water in which 90% of the Cl− concentration in normal sea water was reduced by Br− and 10% by acetate. In artificial sea water, in which either 90% of the Cl− was replaced by Br− or 10% was replaced by acetate, embryos developed into plutei with quasi-normal spicules, pluteus arms and archenterons. These findings indicate that deficiency of Cl− results in somewhat abnormal sea urchin embryos. When cells derived from isolated micromeres, were cultured in these Cl− -deficient artificial sea waters, containing Br− in place of more than 70% of the normal Cl− concentration in sea water, spicule formation was strongly inhibited, but pseudopodial cables were well developed. Thus, external Cl− seems to be necessary for at least normal formation of spicule rods. 相似文献
35.
In unfertilized eggs of the sea urchin Hemicentrotus pulcherrimus , fertilization membrane formation was induced by an incubation with dimethylsulfoxide (DMSO) for several min at 20°c followed by another incubation in an ice bath. The number of eggs with fertilization membrane, thus obtained, increased in relation to the concentration of DMSO between 1 and 3% (v/v) and was higher than 75% at concentrations above 3%. Fertilization membrane formation by this treatment occurred in Ca2+ free- or Ca2+ , Mg2+ free- artificial sea water containing EGTA (50 mM) and was inhibited by verapamil. In the presence of DMSO, the membrane formation was also induced by 2, 4-dinitrophenol or cyanide in considerable number of eggs at 20°c. Eggs remained fertilizable, even when they were kept with DMSO for 1 hr at 20°c. DMSO slightly enhanced respiratory rate in unfertilized eggs and substantially reduced it in fertilized eggs. DMSO-treated eggs exhibited cyanide-insensitive respiratory burst following chilling in an ice bath or by adding DNP or cyanide, in a similar manner to the burst induced by sperm. 相似文献
36.
In embryos of the sea urchin, Hemicentrotus pulcherrimus , as well as in cultured cells derived from isolated micromeres, spicule formation was inhibited by allylisothiocyanate, an inhibitor of H+ , K+ -ATPase, at above 0.5 μM and was almost completely blocked at above 10 μM. Amiloride, an inhibitor of Na+ , H+ antiporter, at above 100 μM exerted only slight inhibitory effect, if any, on spicule formation. Intravesicular acidification, determined using [ dimethylamine -14 C]-aminopyrine as a pH probe, was observed in the presence of ATP and 200 mM KCl in microsome fraction obtained from embryos at the post gastrula stage, at which embryos underwent spicule calcification. Intravesicular acidification and K+ -dependent ATPase activity were almost completely inhibited by allylisothiocyanate at 10 μM. Allylisothiocyanate-sensitive ATPase activity was found mainly in the mesenchyme cells with spicules isolated from prisms. H+ , K+ -ATPase, an H+ pump, probably mediates H+ release to accelerate CaCO3 deposition from Ca2+ , CO2 and H2 O in the primary mesenchyme cells. Intravesicular acidification was stimulated by valinomycin at the late gastrula and the prism stages but not at the pluteus stage. K+ permeability probably increases after the prism stage to activate H+ release. 相似文献
37.
The treatment of sea urchin embryos by Zn2+ followed by culture with Zn2+ -specific chelators such as ethylenediamine-N, N'-diacetic acid and N-hydroxyethylethylenediamine-N, N', N'-triacetic acid, was performed at various developmental stages to find out specific stages for Zn2+ to induce abnormal differentiation. The treatment with 1 mM ZnSO4 at 20°C during a period including two spans of development between 0 and 8 hr and between 14 and 16 hr post fertilization yielded permanent blastulae. Zn2+ -treatment during the former span produced abnormal prisms and plutei with small archenteron. The treatment for a period including only the latter span failed to produce abnormal ones. Zn2+ -treatment during a period including the gastrula stage also produced abnormal spherical embryos. Without the culture with these chelators, abnormal embryos were produced by Zn2+ -treatment performed at any stages before gastrulation. A high zinc amount in the embryos just after the treatment became as low as in normal embryos soon after the culture with these chelators and was maintained during the culture without them. These results indicate that zinc retention occurs in the Zn2+ -treated embryos and causes abnormal differentiation when the treated embryos develop in normal sea water through the Zn2+ -specific periods of development. 相似文献
38.
To determine whether or not the erythrophore originates from xanthophores in the dorsal skin of the brown frog, Rana ornativentris, we morphologically examined the differentiation and migration of the two chromatophore types and their pigmentary organelle formation. At an early tadpole stage, three kinds of chromatophores, xanthophores, iridophores, and melanophores, appeared in the subdermis, whereas the erythrophore did so just before the foreleg protrusion stage. By the middle of metamorphosis, most chromatophores other than erythrophores had migrated to the subepidermal space. Erythrophores, which appeared late in the subdermis, proliferated actively there during metamorphosis and finished moving into the subepidermal space by the completion of metamorphosis. Carotenoid vesicles and pterinosomes within the erythrophores and xanthophores showed several significant differences in structure. In xanthophores, carotenoid vesicles were abundant throughout life, whereas those in erythrophores decreased in number with the growth of the frogs. The fibrous materials contained in the pterinosomes were initially scattered but soon formed a concentric lamellar structure. In erythrophores, the lamellar structure began to form at the periphery of the organelles but at the center in xanthophores. In addition, the pterinosomes of erythrophores were uniform in size throughout development, while those of xanthophores showed a tendency to become smaller after metamorphosis. The pterinosomes of xanthophores were significantly larger than those of erythrophores. These findings suggest that an erythrophore is not a transformed xanthophore, although they resemble each other closely in many respects. 相似文献
39.
IKUO YAMAOKA NOBUYUKI KAWAMURA MANAKO MIZUNO YOSHIMI NAGATANI 《The Journal of eukaryotic microbiology》1984,31(2):267-272
During excystment of an amoeba, Cochliopodium sp., scale formation was examined with light and electron microscopy. This amoeba was covered with scales. When the amoeba encysted, the scales remained on the external surface of the cyst wall. Soon after the induction of excystment the Golgi complex began to develop. Many vesicles were extruded from it and changed into vacuoles. Scales were observed first in the vacuole adjacent to the Golgi complex and later in inside the cyst wall. When the amoeba excysted it had been coated by the newly formed scales. It is suggested that the scale formation is dependent on the activity of the Golgi complex. 相似文献
40.
AKIKO FUJIWARA SHINICHIRO KUSUNOKI EIGORO TAZAWA IKUO YASUMASU 《Development, growth & differentiation》1983,25(5):445-452
Unfertilized eggs of the echiuroid, Urechis unicinctus , were activated by polyamines, such as putrescine, spermidine and spermine at concentrations above 10 μM. Fertilization membrane elevated and germinal vesicle disappeared in unfertilized eggs kept for several min in sea water containing these polyamines. Following the addition of these polyamines, a decrease of pH value in the egg suspension, occurred in a similar manner as observed following fertilization. Several sec after the addition of polyamines to the egg suspension, the respiratoy rate increased very slightly and the sensitivity of the respiration to 2, 4-dinitrophenol, which was lower in unfertilized eggs than in fertilized eggs, became as high as in fertilized ones. Irregular cleavage occurred in the eggs stimulated by polyamines. The incorporation of [3 H]-deoxyadenosine into DNA was initiated by adding polyamines in the unfertilized eggs preloaded with the isotope. The rate of [3 H]-leucine incorporation into protein in the preloaded unfertilized eggs was also enhanced by polyamines, in almost the same manner as observed following fertilization. 相似文献