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M Morisawa

Publications and source records attributed to M Morisawa.

52 records · Page 3Linked to original sources
PubMed1987

Involvement of tyrosine protein kinase in the initiation of flagellar movement in rainbow trout spermatozoa.

Initiation of flagellar motility in spermatozoa of the rainbow trout, Salmo gairdneri, is closely related to phosphorylation of a protein of molecular mass 15 kDa (Morisawa, M., and Hayashi, H. (1986) Biomed. Res. 6, 181-184). We have been able to solubilize the protein and its kinase and then construct an assay system in vitro for the phosphorylation of the 15-kDa protein. In vitro, the protein was phosphorylated in a cAMP-dependent manner. The phosphorylation absolutely required the presence of Mg2+ ions. at millimolar concentrations, but not of Ca2+ ions. The amino acid residue which was phosphorylated in the 15-kDa protein was tyrosine. The 15-kDa protein was purified to near homogeneity by affinity chromatography on a column of adenosine nucleotides conjugated to Eupergit and ion-exchange chromatography on DEAE-cellulose. The effects of synthetic inhibitors of protein kinase on the phosphorylation of the 15-kDa protein were also studied.

Animals↗
PubMed1987

Short-term changes in levels of cyclic AMP, adenylate cyclase, and phosphodiesterase during the initiation of sperm motility in rainbow trout.

In order to clarify the role of the system that generates and degrades cyclic AMP during the initiation of motility of trout sperm, short-term changes in levels of intraspermatozoal cyclic AMP, adenylate cyclase, and phosphodiesterase were measured. Levels of cyclic AMP and the activity of adenylate cyclase increased and reached a maximum level 1 sec after transfer of sperm to K+-free medium, where they became motile, and then decreased rapidly. However, there were no changes in either parameter in sperm which remained immotile in K+-rich medium. In addition, an increase in the activity of phosphodiesterase was observed 4 sec later than the increase in levels of cyclic AMP and adenylate cyclase. These findings suggest that a very rapid change in the level of intracellular cyclic AMP occurs within 1 sec, at the moment of spawning, by the activation of adenylate cyclase and phosphodiesterase, and regulates the initiation of trout sperm motility.

Adenylyl Cyclases↗
PubMed1987

Effect of osmolality on the initiation of sperm motility in Xenopus laevis.

1. Seminal plasma of the South African clawed toad Xenopus laevis exhibited osmolality around 250 mosmol/kg isotonic to blood plasma. 2. Spermatozoa remained immotile when the semen was diluted in solutions of 100 mM NaCl, 100 mM KCl or 200 mM glucose containing 20 mM Hepes-NaOH buffer which exhibited almost the same osmolalities (approximately 240 mosmol/kg) as seminal plasma. 3. The spermatozoa became motile in these three solutions if the osmolalities were decreased. 4. These suggest that motility of Xenopus sperm is suppressed by seminal osmolality in the reproductive organ and initiated by a decrease of osmolality when they are spawned into hypotonic fresh water.

Animals↗
PubMed1986

Acquisition of potential for sperm motility in rainbow trout and chum salmon.

The male reproductive organ of rainbow trout and chum salmon consists of a pair of testes and sperm ducts. Spermatozoa in the distal portion of the sperm ducts exhibit full motility in the K+-free medium. However, spermatozoa from the testis were almost immotile in this medium. This suggests that the spermatozoa acquire a capacity for movement during their passage from the testis along the sperm duct. In chum salmon migrating into a bay, the sperm duct was almost empty. However, after the fish have travelled upstream for 1 km to their spawning ground in the river, the spermatozoa have left the testis, moved into the sperm duct and are capable of becoming motile. Thus it is probable that the process of acquiring the ability to move occurs within a relatively short period in this simple reproductive organ. Additionally, testicular spermatozoa demembranated with Triton X-100 exhibited motility, although the motility was less than that of demembranated spermatozoa from the sperm duct, suggesting that the acquisition of motility may correspond with the development of some function of the plasma membrane.

Animals↗
PubMed1983

Effects of potassium and osmolality on spermatozoan motility of salmonid fishes.

In salmonid fishes, rainbow trout and masu salmon, and the plecoglossid fish, ayu, seminal plasma had an osmolality around 300 mosmol kg-1 isotonic to the blood plasma, and contained a higher concentration of potassium than the blood plasma. Spermatozoa of salmonid fishes were motile when semen was diluted 1:100 with solutions of sodium chloride or mannitol, over the osmotic range of 0-300 mosmol kg-1. They were immotile in sodium chloride solution containing several mM potassium. This indicates that osmolality is not an essential determinant of sperm motility in the Salmonidae, and that sperm motility in these species is suppressed by the seminal potassium in the sperm duct, and initiated by a decrease in potassium concentration surrounding spawned spermatozoa when they are released into fresh water.

Animals↗
PubMed1983

Effects of osmolality and potassium on motility of spermatozoa from freshwater cyprinid fishes.

Spermatozoa of freshwater Cyprinidae (goldfish, carp, crucian carp and dace) remained immotile when the semen was diluted in solutions of NaCl, KCl, mannitol or glucose iso-osmolar to the seminal plasma (300 mosmol kg-1). The spermatozoa became motile in media containing these solutes if the osmolality was lower than that of the seminal plasma, suggesting that motility is suppressed by the osmolality of the seminal plasma in the sperm duct and initiated by a decrease of osmolality upon spawning into fresh water. Potassium was a major component of seminal plasma, having a concentration 20-30 times higher than that in the blood plasma in goldfish and carp. Sodium concentration in seminal plasma was lower than that in blood plasma. Potassium increased viability and speed of sperm movement at a concentration below that in the seminal plasma, whereas sodium and the nonelectrolytes were less effective. Potassium released with spermatozoa at spawning may therefore stimulate motility which has already been initiated by the decrease of osmolality.

Animals↗
PubMed1983

Initiation of sperm motility in teleosts.

In salmonid fish (rainbow trout and chum salmon) or freshwater cyprinid fish (goldfish), change of potassium concentration or osmolality of the environment surrounding the spermatozoa at spawning in fresh water directly affect the flagellum and regulate the initiation of sperm motility. A change in these external factors induces intraflagellar cAMP through some changes of plasma membrane in flagellum and cAMP triggers the initiation of axonemal movement through activation of cAMP-phosphorylation system in initiation of sperm motility in teleosts.

Animals↗
PubMed1980

Osmolality and potassium ion: their roles in initiation of sperm motility in teleosts.

Spermatozoa that are quiescent in electrolyte and nonelectrolyte solutions isotonic to seminal plasma show motility when the semen is diluted with hypotonic solution in freshwater teleosts (four species tested) and with hypertonic solution in marine teleosts (five species tested). Decrease or increase, respectively, in osmolality of the environment may be the factor initiating sperm motility in these species. The motility of chum salmon spermatozoa in a sodium chloride solution isotonic to seminal plasma is completely suppressed by approximately 10 millimoles of potassium per kilogram; topminnow spermatozoa, however, were immotile in a nonelectrolyte solution, and motility was induced by electrolytes, especially potassium. Thus ions, rather than osmolality, may be an essential determinant of sperm motility in salmonid and viviparous teleosts.

Animals↗
PubMed1976

HCO-3-activated adenosine triphosphatase in intestinal mucosa of the eel.

An HCO-3-activated and SCN--inhibited ATPase (ATP phosphohydrolase, EC 3.6.1.3) found in homogenates of intestinal mucosa of the eel was solubilized by Triton X-100. Optimal HCO-3-concentration and pH for the enzyme were 25 mM and 8.7, respectively. HCO-3-ATPase activity in both homogenate and solubilized preparations increased after seawater adaptation. This adaptive increase in enzyme activity was also observed in the gills and the kidney. The HCO-3-ATPase seems to be related to transport mechanisms, especially for Cl-, in osmoregulatory surfaces of the eel.

Adenosine Triphosphatases↗
PubMed1976

Heavy metals and spermatozoan motility. III conformational changes induced by divalent cations and by ATP in flagellar proteins.

Conformational changes of flagellar proteins of sea urchin spermatozoa caused by divalent cations and nucleotides were investigated by examining the circular dichroism spectra of axonemes and outer doublet microtubules. The alpha-Helix content of the flagellar components was diminished in the presence of zinc, cadmium and mercury, while no other heavy metals contributed to such a change. The original content of alpha-helix was restored by the subsequent addition of ATP or GTP, the former being more effective. An oscillation was found to occur in the alpha-helix content measured at 222 micron in the presence of zinc and ATP. On the other hand, ATP caused a marked reduction in alpha-helical structures of axonemes in the presence of magnesium or calcium, especially in a medium containing KCl. The effect was rather specific for ATP. The obtained results were discussed in relation to the basic mechanisms of spermatozoan motility.

Adenosine Triphosphate↗