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C Katagiri

Publications and source records attributed to C Katagiri.

At least 73 records · Page 4Linked to original sources
PubMed1987

Small-angle x-ray scattering study of insect lipophorin.

The structure of lipophorin in insect blood (hemolymph) was investigated by a small-angle x-ray scattering method over the temperature range 0-45 degrees C. The small-angle x-ray scattering profile of lipophorin exhibited a symmetrical sphere with heterogeneous internal electron density. Cockroach and locust lipophorins, which contain hydrocarbons, demonstrated centrosymmetrical distribution of electron density inside the particles. A previous study suggested that the hydrocarbon-rich region is located in the core of lipophorin particle (Katagiri, C., Kimura, J., and Murase, N. (1985) J. Biol. Chem. 260, 13490-13495). Distance distribution functions, P (r), calculated for a simulated three-layer model (electron-rich shell, middle layer, and electron-deficient core) with radial electron density distribution, show good agreement with those observed experimentally for cockroach and locust lipophorins. The dimensions and electron density obtained for the middle layer reveal that this layer is occupied mainly by diacylglycerol and apolipophorin II. Thus, the present study together with previous reports strongly suggest that insect lipophorin is composed of centrosymmetrical three layers; an outer shell with apolipophorin I and phospholipid, a middle layer with diacylglycerol and apolipophorin II, and a core with hydrocarbons.

Animals↗
PubMed1987

Analysis of allotolerance in thymectomized Xenopus restored with semiallogeneic thymus grafts.

The triploid J strain Xenopus laevis (MHC haplotype, j/j/j) were thymectomized as early larvae, and in the adult stage each animal was given a pair of thymuses or lymphocytes from semiallogeneic diploid donor frogs (j/k). The alloreactivity of host frogs was restored to third-party donors in terms of skin graft rejection and mixed leukocyte reaction, but there was specific unresponsiveness against the k haplotype. Grafting of heavily irradiated (10,000 rads) thymuses also restored host reactivity with induction of tolerance to the k haplotype. In the latter frogs, all thymic and splenic lymphocytes were of host origin. Injection of splenocytes from the restored frogs into secondary thymectomized J frogs not only restored immunocompetence but also transferred specific tolerance to the k haplotype. Injection of lymphocytes from the restored frogs to normal frogs failed to transfer specific tolerance by both in vivo and in vitro immune tests. The results suggest that a selective deletion of the T cell population reactive to the k haplotype was maintained in the T-cell-restored frogs.

Animals↗
PubMed1987

Tolerance induced by grafting semi-allogeneic adult skin to larval Xenopus laevis: possible involvement of specific suppressor cell activity.

Major histocompatibility complex (MHC)-homozygous Xenopus laevis were rendered tolerant to semi-allogeneic antigens by grafting skins of adult frogs during larval stages (larvally induced tolerance), and this tolerant state was compared with the tolerance induced in early thymectomized frogs by the grafting of semi-allogeneic nonlymphoid thymuses (thymus-reconstituted tolerance). In contrast to a total inability of thymus-reconstituted frogs both to reject skins and to exhibit a mixed leukocyte reaction (MLR) against the semi-allogeneic donor, larvally induced tolerant frogs showed a strong MLR against leukocytes of the tolerizing skin donor (split tolerance). Breakdown of the tolerant state in thymus-reconstituted frogs were easily accomplished by inoculation with syngeneic splenocytes, but this breakdown was extremely difficult to achieve in frogs with larvally induced tolerance. The injection of splenocytes from larvally induced tolerant frogs into normal frogs significantly suppressed semi-allogeneic graft rejection in the latter group; no suppression was obtained when splenocytes from thymus-reconstituted frogs were used. In addition, in the thymectomized frogs, recovery of allograft rejection capacity against the pertinent semi-allogeneic antigens were suppressed by the injection of splenocytes from larvally induced tolerant frogs, with the degree of suppression depending on the splenocyte dose. These results indicate that the larvally induced tolerant state is maintained by specifically induced suppressor cells affecting the in vivo allograft response but not the MLR.

Animals↗
PubMed1986

Development of pronuclei from human spermatozoa injected microsurgically into frog (Xenopus) eggs.

Human spermatozoa were demembranated with Triton X-100 (TX) and injected into the mature eggs of Xenopus laevis. The nuclei of these spermatozoa decondensed and developed into pronuclei. Chromosomes did not appear in the eggs until the end of a 5-hr incubation period. When the demembranated human spermatozoa were further treated with dithiothreitol (DTT) before they were injected into the eggs, the sperm nuclear decondensation and pronuclear development took place considerably faster than in spermatozoa treated with the detergent alone. By the end of the 5-hr incubation period, decondensed chromatin threads or chromosome-like structures appeared, but none of the eggs cleaved. When human spermatozoa were injected into full-grown ovarian oocytes with intact germinal vesicle (GV) or oocytes which had matured without GV, the nuclei of a proportion of TX-treated and all TX-DTT-treated sperm decondensed but showed no sign of developing into pronuclei. Sperm nuclei injected into maturing oocytes formed condensed chromatin fragments as long as the oocytes were not activated, but they transformed into pronuclei when the oocytes were stimulated with electric shock. These results indicate that the cytoplasmic factors responsible for the decondensation of human sperm nuclei are present in egg cytoplasm independent of GV-materials. We also suggest that the factors controlling development of decondensed sperm nuclei into pronuclei are dependent on GV materials.

Animals↗
PubMed1986

The role of oviducal secretions in mediating gamete fusion in the toad, Bufo bufo japonicus.

A fertilizing sperm of the anuran amphibians has to pass through the jelly envelopes and the vitelline envelope (VE) before making a successful fusion with the egg plasma membrane. Of these the jelly envelopes, secreted by the long pars convoluta (PC) portion of the oviduct, have long been known to be indispensable for the sperm entrance in the egg. The most recent experiments employing dejellied uterine eggs of the toad, Bufo bufo japonicus, revealed that the jelly plays its role in fertilization by its unique capacity of retaining divalent cations (Ca2+ and/or Mg2+) which are essential for a fertilizing sperm. There are other lines of evidence which implicate that the secretions of the uppermost portion of oviduct, p. recta (PR), render the VE penetrable by sperm. We show that the secretory granules (PRG) isolated from PR of ovulating Bufo females by centrifugation in Percoll possess such biological activities as an increase of fertilizability of coelomic eggs and the induction of both the acrosome reaction and a release of the VE lysin from sperm. In addition, the activities of the PRG are inhibited by trypsin inhibitors, and this trypsin-like activity is dependent on Ca2+. These results, combined with the previous immunohistochemical demonstration of the deposition of PR-substance(s) in the VE, lead us to propose that a fertilizing toad sperm is acrosome-reacted in response to the PRG substance deposited in the VE and finds a way of traversing the VE by the released lysin, both of which may be dependent on Ca2+ supplied by jelly envelopes, the product of PC.

Animals↗
PubMed1986

Cosegregation of the polymorphic C4 with the MHC in the frog, Xenopus laevis.

Employing isoeletric focusing combined with enzyme-linked immunoelectrotransfer blot analysis, the fourth component of complement (C4) was analyzed in the two highly histocompatible, major histocompatibility complex homozygous groups (J and K) of Xenopus laevis. Each group had a characteristic C4 isoelectric focusing pattern, i.e., an isoelectric point range of 8.0-8.5 for J (C4jC4j) and 7.6-8.1 for K (C4kC4k). In (J X K)F1 frogs, C4 proteins were expressed in a codominant fashion (C4jC4k). In the backcrossed progeny B1 [J X (J X K)F1], those with C4jC4j rejected (J X K)F1 skins hyperacutely (less than 17 days), were high responders against (J X K)F1 cells, and nonstimulators to J cells in mixed lymphocyte reaction (MLR), but they did not suffer from the graft-versus-host reaction (GVHR), even after the injection of (J X K)F1 cell-stimulated J splenocytes. On the other hand, the B1 frogs with C4jC4k acutely or chronically (greater than 17 days) rejected (J X K)F1 skins, were low or nonresponders against (J X K)F1 cells and high stimulators to J cells in MLR, and they suffered from GVHR after the injection of prestimulated J splenocytes. These results argue for the notion that the genes equivalent to mammalian class III map to the MHC at the phylogenetic level of the anuran amphibian.

Animals↗
PubMed1986

Periodic changes in the rigidity of activated anuran eggs depend on germinal vesicle materials.

The eggs of Xenopus laevis and Bufo bufo japonicus matured in vitro by progesterone were denuded and activated by electrical shock or pricking, and their diameters were determined periodically until the postactivation time equivalent to the 8- to 16-cell stage. Normally matured eggs showed a quick rounding-up and flattening immediately after activation (activation response), followed by a periodic flattening and rounding-up (postactivation response) corresponding to the intervals of early cleavage cycles. When denuded eggs that were induced to mature after removal of the germinal vesicle (GV) were activated, they showed a normal activation response, but retained the rounded-up state without exhibiting the periodic postactivation changes. Injection of GV materials back into enucleated Bufo oocytes and determination of the postactivation flattening 120 min after activation revealed that the extent of flattening correlated well with the amount of GV materials injected, provided injection was made before the first polar body was emitted. Thus, postactivation flattening, but not activation flattening, is an active property of eggs established under the influence of the GV and is linked to the periodical changes of rigidity during early cleavage cycles.

Animals↗
PubMed1985

Structural studies of lipophorin in insect blood by differential scanning calorimetry and 13C nuclear magnetic relaxation measurements. Location of hydrocarbons.

The possible structure of lipophorin in insect blood (hemolymph) was investigated by differential scanning calorimetry (DSC) and 13C nuclear magnetic relaxation studies. The DSC heating curves of intact lipophorins showed endothermic peaks between -3 and 40 degrees C for lipophorins which contain hydrocarbons, whereas no such peaks were observed for lipophorins which do not contain this lipid. Hydrocarbon fractions isolated from the lipophorins showed endothermic peaks similar to those obtained from intact lipophorin in terms of the transition temperatures, the shapes, and the enthalpy changes. 13C spin lattice relaxation times of the (CH2)n resonance of hydrocarbons of intact lipophorin were measured as a function of temperature and revealed that the motions of hydrocarbon chains changed coincidentally with the onset and offset of phase transition. These data suggest the presence of a hydrocarbon-rich region within the lipophorin particles.

Animals↗
PubMed1985

Differential participation of ventral and dorsolateral mesoderms in the hemopoiesis of Xenopus, as revealed in diploid-triploid or interspecific chimeras.

The thymocytes in the early larvae of Xenopus laevis have been shown to be derived from precursor cells immigrating interstitially through the mesenchyme into the organ rudiments at 3-4 days of age (Nieuwkoop and Faber stages 42-45). Orthotopic grafting of diploid tissues onto triploid stage 22 embryos followed by ploidy analyses of their hemopoietic cells revealed that both thymocytes and erythrocytes in early larvae are derived from the ventral blood islands (VBI), whereas those in late larvae and adults come mainly from the dorsolateral plate (DLP). To study how the VBI cells of embryos at stage 22 participate in hemopoiesis, a number of interspecific chimeras were produced in X. laevis and X. borealis embryos. Sections of the chimeras at various developmental stages were examined by employing the unique stainability of X. borealis nuclei to quinacrine as a marker; the results show that the VBI-derived cells enter into the circulation around stage 35/36, and that some of them leave the blood vessels to migrate interstitially through the mesenchyme toward the thymic rudiment during stages 43-45. A minor population of the VBI-derived cells was also found extravascularly in the mesonephric primordia. In contrast to the VBI, the DLP-derived cells contributed to the hemopoietic cell population not in early larvae, but in late ones as a major constituent in the mesonephros, thymus, liver, and peripheral blood.

Animals↗
PubMed1985

Characterization of the fourth component of complement in the serum of the clawed frog Xenopus laevis.

The 202,000 MW protein XC, which is distinct from C3 but is essential for antibody-dependent haemolytic activity against SRBC, was obtained from Xenopus plasma following polyethylene glycol precipitation, ion-exchange chromatography and gel-filtration. The protein required other components of the Xenopus serum in order to lyse sensitized SRBC, but did not lyse unsensitized RRBC through the alternative pathway. The protein, contained at 0.17 mg/ml in the original plasma, comprised three distinct subunits of 96,000, 76,000 and 26,000, which were linked by disulphide bonds. Digestion by trypsin resulted in a specific cleavage of the 96,000 subunit and a conversion of its immunoelectrophoretic mobility to the anodal side, leaving the 76,000 and 26,000 subunits intact. The treatment with SDS and urea resulted in the splitting of the 96,000 subunits into 48,000 and 45,000 components, but this splitting was inhibited upon pretreatment with methylamine, suggesting the presence of a thiol ester bond in the 96,000 subunit. The amino acid composition of the XC revealed a striking resemblance to that of human C3 and C4. We therefore conclude that the 202,000 protein isolated in this study represents the C4 which plays an essential role in the classical haemolytic pathway.

Amino Acids↗
PubMed1984

In vitro induction of sperm nucleus decondensation by cytosol from mature toad eggs.

An in vitro assay was performed on the cytosol from oocytes of the toad, Bufo bufo japonicus, to examine the cytoplasmic activity that induces sperm nucleus decondensation (SND). When the sperm, pretreated for 15 min with 0.05% Triton X-100, were incubated in cytosol obtained from mature eggs (18 h post-hormone treatment: PHT) 30-60 min after activation, their nuclei elongated and swelled markedly to take a spherical shape between 1 and 2 h after incubation. The treatment of such detergent-treated sperm nuclei with dilute HCl significantly enhanced this process of nuclear decondensation. The SND activity was retained in the pellet after centrifugation at 105, 000g for 1 h. It was completely inhibited by EGTA (1 mM) and serine protease inhibitor (1 mM), though not at all by soybean trypsin inhibitor (1 mg/ml). The cytosol from unactivated eggs at 18 h PHT had hardly any SND activity, but was induced to exhibit a strong activity when 10 mM Ca2+ was added to the extraction medium. No SND activity was observed in the cytosol from full-grown ovarian oocytes (0 h PHT), oocytes at the first meiotic metaphase (11 h PHT), or activated oocytes at 18 h PHT from which the germinal vesicle had been removed before the hormone treatment. Electron-microscopic observations revealed that detergent- and acid-treated sperm had completely lost their nuclear envelopes, but, after exposure to active egg cytosol, the decondensed nuclei were surrounded by continuous membranous envelopes. These results point to the importance for the formation of swollen nuclei in fertilized eggs of the membrane system in mature egg cytoplasm that may be activated by Ca2+ at the time of egg activation.

Animals↗
PubMed1984

Toad egg-jelly as a source of divalent cations essential for fertilization.

Dejellied uterine eggs of the toad Bufo bufo japonicus are not fertilizable in 1/20 De Boer's solution (1/20 DB), but are fertilized when inseminated in a uv-solubilized jelly (UVJ) or the dialyzate of UVJ (UVJD). The present study was carried out to define this fertilization-supporting activity of egg-jelly. Dejellied eggs were fertilized in a high frequency when inseminated in a medium containing the ashes obtained by heating UVJD at 600 degrees C for 16 hr. Similarly, a reconstituted salt solution (RSS), which mimics the ionic composition of UVJD, supported a high rate of fertilization. To be effective in fertilization, however, RSS had to be present at the time of insemination. Analyses of individual salts revealed that dejellied eggs are successfully fertilized in CaCl2 and/or MgCl2 at 1-5 mM, only slightly in KCl at 10 mM, but not at all in NaCl at any of the concentrations tested. The activity of UVJD was lost reversibly when divalent cations were chelated by EDTA. The fertilization of dejellied eggs is therefore possible in a medium without any organic components of egg-jelly, provided that 2-5 mM Ca2+ or Mg2+ is present. Sperm were motile in media containing cations below 20-25 mM, regardless of the ionic composition. The egg-jelly possessed cations in a concentration of about 130 mM, but most ions were lost from intact jelly on immersion of eggs in water for 2-3 min, accompanied by the acquisition of fertilizability by sperm. Examination of the behavior of salts on dialysis or gel-filtration of jelly molecules revealed that the jelly retains Ca2+ and Mg2+, and possibly K+ as well, but not Na+ and Cl-. We propose that toad egg-jelly plays a function in fertilization by retaining Ca2+ and/or Mg2+ around each egg at the level necessary for successful sperm entrance into the egg.

Animals↗
PubMed1984

Elicitation of weak immune response in larval and adult Xenopus laevis by allografted pituitary.

To test the claim that tolerance to organ-specific self antigens is established during the ontogenic development of the immune system, pituitary anlagen were removed from early tailbud embryos of Xenopus laevis, and the resulting hypophysectomized tadpoles were grafted with pituitaries after the tadpoles had become immunocompetent. The result was that none of the histocompatible or allogeneic pituitary grafts was rejected throughout an observation period of 100 days. Subsequent experiments revealed that hypophysectomy does not affect the development of immune responsiveness. In addition, allogeneic pituitary grafts were usually not rejected by unoperated, normal tadpoles or froglets, although they suffered lymphoid invasion to various degrees. However, a significant number of allogeneic pituitaries was rejected when they were grafted, either after or at the same time as the grafting of skin from the pituitary donors. We conclude that the pituitary of Xenopus possesses weak transplantation antigens or expresses them in ways that make them less accessible to the immune surveillance system of the allogeneic host.

Animals↗
PubMed1984

Isolation and characterization of the third component of complement in the serum of the clawed frog, Xenopus laevis.

The hemolytic activity against SRBC in the serum of normal Xenopus is dependent on specific antibody and both Ca++ and Mg++, whereas the activity against RRBC is dependent on Mg++ alone. Both of these hemolytic activities disappeared after treatment of the serum with zymosan or with the specific rabbit antiserum against one of the zymosan-binding proteins in Xenopus serum. By using this antiserum as a probe, a complement component (XC) was purified as a single entity from the Xenopus plasma after polyethylene glycol precipitation, DEAE-Sepharose CL-6B, Sepharose CL-6B, and Sephadex G-200 column chromatographies. The XC, contained at 2.3 mg/ml in normal serum, showed an electrophoretic mobility of beta-globulin, with a m.w. of 204,000 (204K) comprising two distinct subunits of 125K and 85K, which are linked with each other by disulfide bonds. The 204K protein exhibited a strong hemolytic activity in association with other components in Xenopus serum. Digestion of 204K protein by trypsin resulted in a specific cleavage of the 125K subunit and a conversion of its immunoelectrophoretic mobility to the anodal side, leaving the 85K subunits intact. The treatment of XC with SDS and urea resulted in the splitting of 125K subunits into 78K and 40K, but this splitting was inhibited upon pretreatment with methylamine, suggesting the presence of a thiol ester bond in the XC. The amino acid composition of the XC revealed a striking resemblance to that of mammalian C3. In all aspects, the 204K protein (XC) is regarded as representing the C3 of Xenopus laevis, which plays a key role in both the classical and alternative hemolytic pathways.

Animals↗
PubMed1983

Response to skin grafts exchanged among siblings of larval and adult gynogenetic diploids in Xenopus laevis.

Gynogenetic diploid individuals were produced in an anuran amphibian, Xenopus laevis, and their response to skin grafts exchanged among siblings was studied. All skin grafts exchanged among nongynogenetic sibling froglets, as well as those from genetically unrelated donors, were rejected within 30 days. More than half (57%) of the gynogens that received grafts from sibling partners exhibited a prolonged survival (over 30 days), including long-term survival of over 120 days in 13%. The skin grafted from genetically unrelated froglets onto Nieuwkoop and Faber stage 42-56 larvae and onto perimetamorphic stage 58-65 animals was rejected within 30 days. Similarly, most (96%) of the skin grafts from outbred sibling froglets onto larvae at these stages were rejected acutely or subacutely (12-39 days). However, the skin grafted from sibling froglets to gynogens at larval stage 42-56 and perimetamorphic stage 58-61 enjoyed a long-term survival significantly more frequently (81%) than that in the final metamorphic (stage 64-65) counterparts (57%). These results support the view that in the adult Xenopus allograft responses are reactions to a single MHC as well as to cumulative, multiple minor H-locus barriers. The results also suggest that in larval stages the responses against minor H-locus barriers are generated only mildly.

Aging↗