Dynein 1 from rainbow trout spermatozoa: immunological similarity between trout and sea urchin dynein 1

Analysis of mammalian dynein using antibodies against A polypeptides of sea urchin sperm flagellar dynein

Two different affinity-purified polyclonal antibodies were prepared against A polypeptides of dynein 1 extracted from sea urchin sperm. These antibodies, named AD1 and AD2, reacted exclusively with the alpha and beta heavy chains of dynein 1. Using these antibodies, we analyzed their cross-reactivity with dynein of mammalian cells. Immunohistochemically, both AD1 and AD2 stained dynein-related structures such as cilia of rabbit tracheal epithelia and flagella of rat spermatozoa. Immunoblots of the proteins extracted from mammalian cilia and flagella revealed the presence of A polypeptide-like proteins which cross-reacted with AD1 and AD2. Immunoblot analysis showed that the cross-reactive proteins were localized to the 370-kDa band of rabbit cilia and the 390- and 350-kDa bands of rat sperms. The reaction patterns showed that there were some differences between the two antibodies. On ciliary protein immunoblots, AD1 recognized about half of the broad band region which reacted with AD2, and AD1 also recognized only the 350-kDa band of the flagella extract, suggesting that the antibody reveals only a beta-like polypeptide. Immunoprecipitation studies using the ciliary proteins and AD2 confirmed that the immunoreactive protein had ATPase activity. Given these results, we have characterized mammalian dyneins previously reported by other laboratories.

Trout sperm motility. The transient movement of trout sperm is related to changes in the concentration of ATP following the activation of the flagellar movement

For freshwater fish the motile period of sperm is extremely brief, even after a dilution in isotonic media. This result is in contrast to most other animals (ranging from invertebrates to mammals), in which sperm are generally motile for at least several hours. We have analyzed the reasons for the brevity of this movement by studying the relationships between the metabolism of trout sperm and the activation of their motility upon dilution. Sperm motility was not initiated when the dilution medium contained an elevated concentration of potassium (20-40 mM), but dilution in an isotonic solution of sodium chloride triggered an immediate activation of motility, and sperm swam vigorously. Motility of sperm decreased rapidly and 15 s after dilution sperm were moving slowly in small circles. Sperm became abruptly immotile at 20-30 s and flagella straightened. When millimolar concentrations of Ca2+ were also present in the dilution medium, movement did not stop abruptly, flagella kept beating and stopped only after 1-2 min. When sperm remained immotile they retained a high concentration of ATP. The activation of motility induced a rapid decrease of ATP. In the absence of calcium, and after the cessation of motility, ATP increased slowly back to its original concentration. In the presence of millimolar concentrations of calcium the concentration of ATP decreased to a very low level and remained low thereafter. The progressive decrease of the flagellar beat frequency, that had been observed during the period of trout sperm movement, might be related to the rapid exhaustion of intraflagellar ATP. Motility could be reinduced in sperm that had recovered high concentrations of ATP, demonstrating the functional integrity of the motile apparatus even after flagellar arrest. In conclusion we suggest that the maximum duration of trout sperm motility, at most 2 min (as a consequence of a depletion of ATP during the movement), is due to a low mitochondrial oxidative phosphorylation capacity.

Studies on the flagellar ATPase of bull spermatozoa: extraction and characterization

Adenosine triphosphatase (ATPase) activity of flagella isolated from ejaculated bull sperm was solubilized by 5 min exposure to 0.6 M KCl at 4 degrees C. ATPase activity in the flagellar extract was characterized with respect to enzyme, substrate, activator ion, salt, and hydrogen ion concentration. Flagellar extract required the presence of a divalent cation for activity: Mg2+, Ca2+, or Mn2+ could function as activator, but Zn2+ or Cd2+ could not. Magnesium-activated ATPase was maximal in the presence of Mg2+ and ATP in equimolar concentrations and at alkaline pH. Calcium activated ATPase was maximal over a wide range of Ca2+:ATP ratios and at pH 8.0. The presence of increasing concentrations of Na+ and/or K+ ions in the assay medium (0.5-300 mM) had no effect on the ATPase activity of flagellar extract.

Immunological dissimilarity in protein component (dynein 1) between outer and inner arms within sea urchin sperm axonemes

The 0.5 M KCl-treatment solubilizes the outer arms from sea urchin sperm axonemes. Approximately 30 percent of A-polypeptide, corresponding to dynein 1 in SDS- polyacrylamide gel, was solubilized by this treatment (as SEA-dynein 1). Electron microscopic observation indicated that the extracted axonemes lacked the outer arms in various degrees. The DEA-dynein 1 was that the extracted axonemes lacked the outer arms in various degrees. The SEA-dyenin 1 was purified and an antiserum against it was prepared in rabbits. The specificity of antiserum to dynein 1 was determined by immunoelectrophoresis and ouchterlony's double-diffusion test. The anti-dynein 1 serum inhibited ATPase activity of purified SEA-dynein 1 by 95 percent. By the indirect peroxidase-conjugated antibody method, the loci of SEA-dynein 1 within the intact, salt- extracted and mechanically disrupted axonemes were determined to be the outer arms: deposition of electron-dense materials which represents their localization was detected at the distal ends of the outer arms, in the case of intact axonemes. The 5-6 cross- bridge was hardly decorated. No decoration was seen in the salt-extracted axonemes lacking all the outer arms. In disrupted axonemes, which consist of single to several peripheral doublets, electron-dense materials were deposited only on the outer arms. Approximately 73 percent of axonemal ATPase activity sensitive to antiserum was solubilized by repeated salt-extractions. One-half of A-polypeptide (SEA-dynein 1 located at the outer arms) was contained in the pooled extracts. The extracted axonemes contained another half of A-polypeptide (SUA-dynein 1 supposed to locate at the inner arms) and retained 31 percent of axonemal ATPase activity that was almost resistant to antiserum. Solubilized SUA-dynein 1 was immunologically the same as SEA-dynein 1. This result indicates that in situ SUA-dynein 1 did not receive anti-dynein 1 antibodies, coinciding with the result obtained for salt-extracted axonemes lacking all the outer arms by the enzyme-antibody method mentioned above. These observations suggest that immunological dissimilarity in dynein 1 between outer and inner arms but do not tell us that the inner arms do not contain dynein 1.

Effects of antibodies against dynein and tubulin on the stiffness of flagellar axonemes

Antidynein antibodies, previously shown to inhibit flagellar oscillation and active sliding of axonemal microtubules, increase the bending resistance of axonemes measured under relaxing conditions, but not the bending resistance of axonemes measured under rigor conditions. These observations suggest that antidynein antibodies can stabilize rigor cross-bridges between outer-doublet microtubules, by interfering with ATP-induced cross-bridge detachment. Stabilization of a small number of cross-bridge appears to be sufficient to cause substantial inhibition of the frequency of flagellar oscillation. Antitubulin antibodies, previously shown to inhibit flagellar oscillation without inhibiting active sliding of axonemal microtubules, do not increase the static bending resistance of axonemes. However, we observed a viscoelastic effect, corresponding to a large increase in the immediate bending resistance. This immediate bending resistance increase may be sufficient to explain inhibition of flagellar oscillation; but several alternative explanations cannot yet be excluded.