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Biomedical subjects

M Morisawa

Publications and source records attributed to M Morisawa.

At least 37 records · Page 2Linked to original sources
PubMed1996

Extracellular Ca2+ entry and Ca2+ release from inositol 1,4,5-trisphosphate-sensitive stores function at fertilization in oocytes of the marine bivalve Mytilus edulis.

An oocyte of the marine bivalve Mytilus edulis, which is arrested at metaphase I, reinitiates meiosis at fertilization. The fertilized oocyte shows increases in intracellular Ca2+ ([Ca2+]i) comprising three different phases: an initial large [Ca2+]i transient, a subsequent low but sustained [Ca2+]i elevation, and repetitive small [Ca2+]i transients. In this study, we have investigated the sources and mechanisms of the sperm-induced [Ca2+]i increases. Application of methoxyverapamil (D-600), an inhibitor of voltage-dependent Ca2+ influx, suppressed the initial [Ca2+]i transient but did not affect the following two phases of [Ca2+]i changes. Injection of heparin, an antagonist of the inositol 1,4,5-trisphosphate (IP3) receptor, inhibited the later two phases without much affecting the initial transient. Combined application of D-600 and heparin almost completely abolished the three phases of the sperm-induced [Ca2+]i changes. Furthermore, Ca2+ influx caused by seawater containing excess K+ was blocked by D-600 but not by heparin, and IP3-induced Ca2+ release caused by photolysis of injected 'caged' derivatives of IP3 was blocked by heparin but not by D-600. These results strongly suggest that two types of Ca2+ mobilization systems, the extracellular Ca2+ entry responsible for an initial [Ca2+]i transient and the IP3 receptor-mediated Ca2+ release responsible for the following two phases of [Ca2+]i changes, function at fertilization of Mytilus oocytes.

Animals↗
PubMed1996

Prosthodontic treatment for a patient with advanced hydantoin-associated gingival hyperplasia: a case report.

A patient in whom gingival hyperplasia was caused by prolonged use of an anticonvulsant drug (hydantoin) is described. Advanced gingival hyperplasia and significant displacement of the remaining teeth caused severe damage, especially to the patient's appearance. It was not possible to cure the problems completely with routine periodontal treatment. It was decided to extract all the remaining teeth and restore function and esthetics early with complete dentures. Cephalometric analysis was used to determine the degree to which the teeth had drifted. During fabrication of the dentures, the analysis was very useful in deciding the position of the anterior teeth and checking the vertical dimension of occlusion.

Adult↗
PubMed1995

Vitellogenins of Oreochromis niloticus: identification, isolation, and biochemical and immunochemical characterization.

Two native forms of vitellogenin (EIP1 and EIP2) were identified in the plasma of Oreochromis niloticus. They were present in females and were estrogen-inducible in males. Both were phosphoglycolipoproteins and both immunoreacted with the antiserum raised against egg proteins. Two prominent bands (EIpp1 and EIpp2; corresponding to 185 and 120 kDa, respectively), observed on sodium dodecyl sulfate-polyacrylamide gels, were induced by estradiol treatment of males and immunoreacted with the antiserum against egg proteins. EIP1 and EIP2 were isolated by precipitation with Mg2+ ions and ethylenediamine tetraacetic acid, preparative polyacrylamide gel electrophoresis, and electroelution. During purification the fractions containing EIP1 and EIP2 also retained EIpp2 and EIpp1, respectively. Immunoblot analyses using affinity-purified antibodies against EIP1, EIP2, EIpp1, and EIpp2 confirmed that EIP1 and EIP2 were at least composed of EIpp2 and EIpp1, respectively. These results suggest that at least two immunochemically different proteins are induced and are secreted into the blood to serve as vitellogenin and to provide a source of nutrient for the developing embryo of Oreochromis niloticus.

Animals↗
PubMed1995

Identification of a 10 S trypsin-like protease that cross-reacts with anti-proteasome antibody in sea urchin egg jelly.

We have identified 27- and 26-kDa polypeptides in sea urchin egg jelly, both of which cross-reacted with the antibody against 20 S proteasome (multicatalytic proteinase) isolated from sea urchin sperm. Separation of egg jelly fraction by gel filtration or sucrose density gradient centrifugation revealed that these polypeptides comigrated as a complex with a molecular size much smaller than that of proteasome: the apparent molecular mass and the sedimentation coefficient were 200 kDa and 10 S, respectively. This protease significantly hydrolyzed the fluorogenic synthetic substrates for trypsin-like protease but little hydrolyzed those for chymotrypsin-like protease. Trypsin-like activity of sperm proteasome was activated up to more than threefold by a low concentration of sodium dodecyl sulfate (SDS), whereas the egg jelly 10 S protease was inhibited by SDS. Two-dimensional immunoblot and peptide mapping revealed that the 26-kDa polypeptide is a degradative product of 27-kDa polypeptide and that the 10 S protease is composed of a proteasome-related single 27-kDa polypeptide and its modified forms. These results indicate the presence of a 10 S novel assembly of a proteasome subunit only with trypsin-like activity.

Amino Acid Sequence↗
PubMed1995

Change in intracellular K+ concentration caused by external osmolality change regulates sperm motility of marine and freshwater teleosts.

We previously demonstrated that osmolality isotonic to the seminal plasma suppresses sperm motility in marine and freshwater teleosts, and exposure of sperm to hypertonicity of sea water or hypotonicity of fresh water, respectively, induces the initiation of sperm motility at spawning. The motile sperm became immotile by return of osmolality to the isotonic osmolality both in a marine teleost, the puffer fish, and a freshwater teleost, the zebrafish. The initiation and termination of sperm motility could be repeated several times by changing surrounding osmolality in both species. In demembranated sperm, motility was suppressed by a K+ concentration equivalent to the seminal salt concentration in both puffer and zebrafish. Demembranated puffer sperm were reactivated when K+ concentration of the reactivating solution increased. Conversely, initiation of motility in the demembranated zebrafish sperm was induced by decreasing K+ concentration. The initiation and termination of the demembranated sperm were alternately repeated by changing K+ concentration of the reactivation solution in both species. Furthermore, intracellular K+ concentration rose when sperm motility of the puffer was initiated in hypertonic solutions. These results suggest that change in external osmolality is converted into change in intracellular K+ concentration, and that the change affects the flagellar axoneme as a signal to initiate or terminate sperm motility. The initiation and termination of motility in the demembranated puffer sperm were caused at a high pH and a low pH of the reactivating solution, respectively, suggesting the contribution of intracellular pH in the regulation of flagellar motility.

Animals↗
PubMed1995

[Home parenteral nutrition for terminal cancer patients--when should we tell the truth about their disease and return them to their home with HPN].

Home parenteral nutrition (HPN) is a significant way to enable terminally ill cancer patients to live with high quality of life at home. However, the most important condition to perform HPN is the patients' desire to return to their home. For this purpose, we should consider in informing them of the truth of their disease. We had three terminal cancer patients who returned to their home with HPN. Cas 1: 52-year-old woman, recurrent stomach cancer. She did not know her cancer. She stayed at home for 45 days with HPN. Case 2: 46-year-old woman, recurrent stomach cancer. She did not know her recurrence of cancer. She stayed at home for only 15 days with HPN. Case 3: 45-year-old woman, recurrent pancreatic head cancer. She knew her disease and her life expectancy. She had 6-year-old daughter and desired to return home. She stayed at home with HPN for 8 months. As we told Case 3 truth of her disease when she was diagnosed as recurrence of cancer, she lived at home with HPN for 8 months. From the experience of three cases, we may concluded that, the sooner the patients are informed the truth about their disease, the longer they can stay at home with HPN and spend their limited time with high QOL.

Female↗
PubMed1994

Implication that potassium flux and increase in intracellular calcium are necessary for the initiation of sperm motility in salmonid fishes.

Flux of K+ and changes in intracellular Ca2+ in the sperm of salmonid fishes were measured with spectrophotometry, ion electrode, microscopic fluorometry, and radioisotope accumulation. Release of K+ occurred at the initiation of sperm motility which is induced by decrease in external K+ and the K+ efflux and sperm motility were inhibited by K+ channel blockers. Intracellular Ca2+ increased within a short period in K(+)-free condition, and the accumulation of 45Ca in sperm cells was higher in motile sperm than that in immotile sperm. The efflux of K+ and the increase in intracellular Ca2+ were suppressed when external K+ concentration increased, i.e., sperm remained immotile. These results suggest that efflux of K+ through K+ channel and subsequent increase in intracellular Ca2+ are prerequisite for the initiation of sperm motility.

4-Aminopyridine↗
PubMed1994

Isolation and properties of a protein complex containing flagellar movement-initiating phosphoprotein from testes of a white salmon.

Phosphorylation of a tyrosine residue within a 15-kDa protein has been found to play a role in the initiation of flagellar movement of quiescent spermatozoa of the rainbow trout, Salmo gairdneri [Morisawa & Hayashi (1986) Biomed. Res. 6, 181-184; Hayashi et al. (1987) J. Biol. Chem. 262, 16692-16698]. In order to find a more accessible source of the 15-kDa protein for biochemical studies, phosphorylation of proteins was studied in other organs from other species. Cell-free extracts from spermatozoa and testes of Salmonidae were prepared and all catalyzed the cAMP-dependent, Mg(2+)-requiring, but Ca(2+)-independent phosphorylation of the 15-kDa proteins. Protein from the testes of a white salmon, Oncorhynchus keta, was isolated by conventional purification methods. The 15-kDa protein in the cell-free extract was found to be complexed with several other proteins such that the 15-kDa protein and its phosphorylating activity were copurified. Isolation of a sufficient amount of the complex for the preparation of antibodies against the various constituents is now possible.

Animals↗
PubMed1994

Monoclonal antibodies against the protein complex that contains the flagellar movement-initiating phosphoprotein of Oncorhynchus keta.

We isolated and characterized several monoclonal antibodies against a protein complex containing the flagellar movement-initiating phosphoprotein (MIPP) that appears to play a crucial role in the initiation of flagellar movement in quiescent spermatozoa of Salmonid fish. The effects of the antibodies on the phosphorylation of MIPP, as well as on the initiation of movement, in model sperm cells were studied. Three monoclonal antibodies, namely, FMI7, FMI18, and FMI27, were found specifically to inhibit both the initiation of flagellar movement and the phosphorylation of MIPP. These antibodies did not recognize denatured MIPP; they only recognized the native antigen. FMI7 exclusively recognized the denatured form of a 38-kDa protein, which may possibly be a protein kinase responsible for the phosphorylation of MIPP. Immunofluorescence analysis in situ of model sperm cells with the antibodies showed that the antigen was localized predominantly in the basal structure of the spermatozoon. Thus, the results clearly demonstrate the involvement of MIPP in the initiation of flagellar movement and the control of flagellar motility.

Animals↗
PubMed1993

Rises of intracellular Ca2+ and pH mediate the initiation of sperm motility by hyperosmolality in marine teleosts.

Spermatozoa of marine teleosts, puffers and flounder, were completely quiescent when they were washed to remove electrolytic components of the seminal plasma and then diluted in nonelectrolyte solutions isotonic to the seminal plasma. Sperm motility was initiated upon dilution in hypertonic nonelectrolyte solutions. These observations suggest that sperm motility is suppressed by seminal osmolality and motility is triggered solely by the increase in external osmolality which occurs at natural spawning in hypertonic seawater. Extracellular Ca2+ had no influence on the osmolality-dependent initiation of sperm motility. However, sperm motility was initiated even in isotonic solution when Ca2+ was introduced into the sperm cells by Ca2+ ionophore. Intracellular Ca2+ increased at the osmolality-dependent initiation of sperm motility under Ca(2+)-free conditions. These results suggest that the release of Ca2+ from intracellular storage in response to the increase in external osmolality has a key role in the initiation of sperm motility. A transient increase in intracellular pH was also observed at the hyperosmolality-dependent initiation of sperm motility. Furthermore, initiation of sperm motility was induced even in isotonic solutions when intracellular pH increased by the treatment with ammonium salts. These results suggest that an increase in intracellular pH, as well as the rise in intracellular Ca2+, has an important role in the initiation of sperm motility in marine teleosts.

Acetates↗
PubMed1993

Roles of pH and cyclic adenosine monophosphate in the acquisition of potential for sperm motility during migration from the sea to the river in chum salmon.

In the natural process of the migration of chum salmon from the sea to the river, spermatozoa moved from the testis to the sperm duct, and the pH value of seminal plasma, concentration of cyclic adenosine monophosphate (AMP) in the sperm cells, and potential for sperm motility increased. Cyclic AMP levels and the potential for motility gradually increased when testis spermatozoa with no capacity for movement were incubated in the artificial seminal plasma of which the pH was much the same as, or higher than, the pH of natural seminal plasma from the sperm duct. Such correlation in motility, pH, and cyclic AMP suggests that the increases in seminal pH and intracellular cyclic AMP level during passage of spermatozoa from the testis to the sperm duct cause the acquisition of potential for motility. Motility of testicular spermatozoa demembranated with Triton X-100 was very low in fish caught in the sea, while motility of spermatozoa from the posterior portion of the sperm duct was much higher in fish caught in the river. Furthermore, nondemembranated, intact spermatozoa showed a lag in the timing of the acquisition of potential for motility vs. demembranated spermatozoa: The demembranated sperm exhibited the potential earlier than the nondemembranated sperm. These data suggest that increase in activity of the motile apparatus, the axoneme, is a prerequisite, in part, for the acquisition of sperm motility, whereas the development of some function of the plasma membrane also contributes to this phenomenon.

Animals↗
PubMed1993

Sperm chemotaxis during the process of fertilization in the ascidians Ciona savignyi and Ciona intestinalis.

Ascidian sperm were activated and attracted to all of the surface of a whole egg. When the whole egg was separated into follicle cells, chorion and test cells, and the egg itself (naked egg), spermatozoa were activated and exhibited chemotaxis toward the vegetal pole of the naked egg. Such activation and chemotaxis were not observed around isolated follicle cells or chorion with follicle cells and test cells, suggesting that a substance released from the vegetal pole of the egg which activates the sperm and orients them to it in the perivitelline space. The chemotaxis index, which was calculated by a newly proposed method, showed that sperm-attracting activity vanished when the egg deformed, suggesting that the release of attractant through the plasma membrane is terminated at the time of fertilization. The supernatant of the egg suspension (egg seawater) showed strong sperm-activating and sperm-attracting activities, which were dialyzable, heat stable, and resistant to proteinases. Thus, these activities may be initiated by a nonproteinaceous small molecule. Spermatozoa which were previously activated with theophylline without the egg factor showed chemotactic behavior to the tip of the capillary in which egg seawater was enveloped. However, spermatozoa exhibited only activation around the tip of the capillary with theophylline. This indicates that sperm activation and chemotaxis could be controlled under a separative mechanism.

Animals↗
PubMed1993

Purification of proteasomes from salmonid fish sperm and their localization along sperm flagella.

We have purified two chymotrypsin-like proteases from chum salmon sperm which have no apparent acrosome structure. Both of them were high molecular mass proteases (650 kDa and 950 kDa by gel filtration) and showed not only chymotrypsin-like activity but also trypsin-like activity. The 650 kDa protease was composed of at least eight or nine kinds of polypeptide with molecular masses ranging from 20 kDa to 30 kDa and was highly activated by low concentrations of SDS. Electron microscopy revealed that the 650 kDa protease was a ring-shaped particle. The 950 kDa protease was shown to contain at least one component that cross-reacts with an antibody against the 650 kDa protease. Finally, we revealed that the 650 kDa protease is located along the sperm flagella, by using immunofluorescence microscopy. The subunit composition, SDS-activation and molecular shape of 650 kDa salmonid protease were quite similar to those of the eukaryotic multicatalytic proteinase (proteasome), which is well known to participate in ATP-dependent degradation of ubiquitinated proteins; and, furthermore, the motility of demembranated sperm of salmonid fish is inhibited by chymotrypsin inhibitors in an ATP-dependent manner. Thus, the protease located in salmonid fish sperm flagella is a proteasome and is a strong candidate for the factor which regulates flagellar motility in an ATP-dependent manner.

Amino Acid Sequence↗
PubMed1992

Two high molecular mass proteases from sea urchin sperm.

Two-types of high molecular mass proteases have been purified from sea urchin sperm using DEAE-Sephacel, hydroxylapatite and Superdex 200 column chromatography. Both proteases showed similar hydrolyzing activities toward synthetic peptides, but they differed in the molecular mass and peptide composition. One was probably identical to a proteasome (multicatalytic proteinase), judging from its molecular mass (650 kDa) and polypeptide composition. The other one was composed of several polypeptides with molecular masses ranging from 24 kDa to 125 kDa and its molecular mass was estimated as 950 kDa by gel filtration. These two proteases, however, were closely related to each other. Immunological studies revealed that the 950-kDa protease comprised at least five subunits of the 650-kDa protease.

Amino Acid Sequence↗
PubMed1992

Chymotrypsin-like protease activity associated with demembranated sperm of chum salmon.

Our previous study suggested that a chymotrypsin-like protease was involved in the motility of chum salmon sperm (Inaba K, Morisawa M, Biomed Res (1991) 12, 435-437). In this study, we examined the peptidase activity of demembranated sperm of chum salmon using ten synthetic peptides. When spermatozoa were treated with 0.04% Triton X-100 for extracting the plasma membrane and the suspension was separated into the Triton-soluble and insoluble fractions by centrifugation, only the hydrolytic activity towards succinyl (Suc)-Leu-Leu-Val-Tyr-4-methylcoumaryl-7-amide (MCA), a typical substrate for chymotrypsin-like protease, was mostly retained in the insoluble fraction. The bulk of the activities toward other substrates was detected in the soluble fraction. Flagellar axonemes isolated from demembranated sperm showed considerable hydrolytic activity toward Suc-Leu-Leu-Val-Tyr-MCA and the activity was still retained in the axoneme even after further washing. The hydrolysis was activated by a low concentration of SDS, suggesting that the protease associated with the axonemes is a multicatalytic ATP-dependent proteinase (proteasome). Motility of demembranated sperm was inhibited by Suc-Leu-Leu-Val-Tyr-MCA in an ATP-concentration-dependent manner. These results suggest that proteasomes associated with flagellar axoneme regulate flagellar motility.

Amino Acid Sequence↗
PubMed1988

Induction of potential for sperm motility by bicarbonate and pH in rainbow trout and chum salmon.

Spermatozoa of rainbow trout and chum salmon, which have no potential for motility in the testis, acquire that potential in the sperm duct. This paper demonstrates that there is little difference between the levels of sodium, potassium, calcium, magnesium, chloride and osmolality of the seminal plasma in the testis and in the sperm duct. However, the bicarbonate concentration of the seminal plasma and the pH value of semen were higher in the sperm duct than in the testis. When immotile spermatozoa obtained from the testis were incubated in artificial seminal plasma with a high pH and containing HCO3-, spermatozoa became motile within 1 h. These results suggest that spermatozoa of salmonid fish acquire the potential for motility as a result of the increase in seminal bicarbonate concentration and pH that occurs as spermatozoa pass from the testis to the sperm duct.

Animals↗