Visualization of centrioles and basal bodies by fluorescent staining with nonimmune rabbit sera.

Several sera from nonimmunized rabbits have been found which stain centrioles and basal bodies by indirect immunofluorescence in a wide variety of cell types. So far, approximately 10% of the rabbit sera that we have examined gave strong positive staining of centrioles and basal bodies. Cytoplasmic networks, mitotic spindles, and ciliary axonemes, however, remain unstained. This specific fluorescent staining of centrioles and basal bodies could not be abolished by absorption of sera with purified brain tubulin. This technique is superior to previous methods for the visualization of basal bodies and centrioles at the light microscopic level and should be useful for rapid and convenient detection of these organelles in large populations of cells.

Presence and indirect immunofluorescent localization of calmodulin in Paramecium tetraurelia.

In this paper we demonstrate the presence and localization of calmodulin, a calcium-dependent regulatory protein, in the ciliated protozoan Paramecium tetraurelia. Calmodulin is demonstrated by several criteria: (a) the ability of whole cell Paramecium extracts to stimulate mammalian phosphodiesterase activity, (b) the presence of an acidic, thermostable, 17,000-dalton polypeptide whose mobility shifts in SDS polyacrylamide gel electrophoresis in the presence of Ca2+, and (c) the affinity of antibodies against mammalian calmodulin for a Paramecium component as demonstrated by both indirect immunofluorescent localization and radioimmunoassay. Indirect immunofluorescence studies reveal that Paramecium calmodulin is distributed in three distinct regions of the cell, i.e., (a) large, spherical cytoplasmic organelles representing perhaps the food vacuoles or other vacuolar inclusions of the cell, (b) along the entire length of oral and somatic cilia, and (c) along a linear punctate pattern corresponding to the kinetics (basal bodies) of the cell.

Structure and mass analysis of 14S dynein obtained from Tetrahymena cilia.

Scanning transmission electron microscopic analysis revealed that the 14S fraction of Tetrahymena dynein was of a mixture of two types of particles in approximately equal proportions. The 14S dynein molecules were roughly ellipsoid in shape with approximate axes of 9.5 and 14.5 nm. About half of the particles had tails 20-24-nm long. By the integration of electron scattering intensities, particles with tails had an average mass of 510 kD with a SD of 90 kD. The globular heads of both types of particles had an average mass of 330 kD with a SD of 60 kD. The mass of the tail structure was about 180 kD. By SDS-PAGE, the 14S dynein consisted of two high molecular mass polypeptides above 300 kD that could be distinguished by immunoblot analysis.

The basal apparatus. Mass isolation from the molluscan ciliated gill epithelium and a preliminary characterization of striated rootlets.

The basal apparatus, consisting of an array of interconnected basal bodies bearing bifurcating striated rootlets encompassing a nucleus, has been isolated from hypertonically deciliated columnar gill epithelial cells of the bay scallop Aequipecten irradians through gentle lysis with Triton X-100. The rootlets, 8-10 mum in length, were not easily preserved with conventional electron microscope fixatives, suggesting that the extent of their contribution to cellular architecture has been somewhat underestimated, even though Englemann described many of the structural details of the basal apparatus in 1880. The striated rootlets were soluble at high but not at low pH, in 2 M solutions of sodium azide and potassium thiocyanate but not sodium or potassium chloride, in 1% deoxycholate but not digitonin, and in the denaturing solvents 6 M guanidine-HC1, 8 M urea, and 1% sodium dodecylsulfate at 100 degrees C. The protein found consistently when rootlets were solubilized migrated on SDS-polyacrylamide gels as a closely spaced doublet with apparent molecular weights of 230,000 and 250,000 daltons. This unique protein, distinct from tropocollagen or various muscle components, has been named ankyrin because of the rootlet's anchor-like function in the cell.

Biochemical studies of the excitable membrane of Paramecium tetraurelia. III. Proteins of cilia and ciliary membranes.

As a first step in the biochemical analysis of membrane excitation in wild-type Paramecium and its behavioral mutants we have defined the protein composition of the ciliary membrane of wild-type cells. The techniques for the isolation of cilia and ciliary membrane vesicles were refined. Membranes of high purity and integrity were obtained without the use of detergents. The fractions were characterized by electron microscopy, and the proteins of whole cilia, axonemes, and ciliary membrane vesicles were resolved by SDS polyacrylamide gel electrophoresis and isoelectric focusing in one and two dimensions. Protein patterns and EM appearance of the fractions were highly reproducible. Over 200 polypeptides were present in isolated cilia, most of which were recovered in the axonemal fraction. Trichocysts, which were sometimes present as a minor contaminant in ciliary preparations, were composed of a very distinct set of over 30 polypeptides of mol wt 11,000--19,000. Membrane vesicles contained up to 70 polypeptides of mol wt 15,000--250,000. The major vesicle species were a high molecular weight protein (the "immobilization antigen") and a group of acidic proteins with mol wt similar to or approximately 40,000. These and several other membrane proteins were specifically decreased or totally absent in the axoneme fraction. Tubulin, the major axonemal species, occurred only in trace amounts in isolated vesicles; the same was true for Tetrahymena ciliary membranes prepared by the methods described in this paper. A protein of mol wt 31,000, pI 6.8, was virtually absent in vesicles prepared from cells in exponential growth phase, but became prominent early in stationary phase in good correlation with cellular mating reactivity. This detailed characterization will provide the basis for comparison of the ciliary proteins of wild-type and behavioral mutants and for analysis of topography and function of membrane proteins. It will also be useful in future studies of trichocysts and mating reactions.

Studies of membrane formation in Tetrahymena pyriformis. II. Isolation and lipid analysis of cell fractions.

A method has been devised to fractionate cells of Tetrahymena pyriformis, yielding pure or highly enriched preparations of cilia, cilia-associated soluble material, pellicles, mitochondria, microsomes, and postmicrosomal supernatant. The method prevents the destructive action of lipolytic enzymes commonly associated with this organism. Analysis of the membrane lipids of these fractions reveals significant differences in lipid composition. Most noteworthy are the high concentrations of phosphonolipid and tetrahymanol in the surface membranes.

Isolation of ciliated or unciliated basal bodies from the rabbit oviduct.

Techniques have been developed for the isolation of basal bodies with cilia attached or for the isolation of only basal bodies from the rabbit oviduct. Oviducts are removed, cut open, and placed in an extraction medium composed of 0.25 M sucrose, 0.001 M EDTA, 0.025 M KCl, 0.02 M Hepes buffer pH 7.5, and 0.05% Triton X-100. After the oviduct is agitated in this medium on a Vortex mixer for (1/2) h, the lumenal cortex of each ciliated cell, containing 200-300 basal bodies with cilia attached, is released as a unit. The cortices and the intact nuclei, which are also released from the disrupted cells, form a pellet when the extraction medium is centrifuged at 600 g for 10 min. When cortices which contain only basal bodies are to be isolated, the oviduct is subjected to conditions which remove the cilia prior to being processed as above. The cilia are removed when the oviduct is placed in a medium of 0.25 M sucrose, 0.01 M CaCl(2), 0.02 M Pipes buffer pH 5.5, and 0.05% Triton X-100 and continuously agitated for 15 min on a Vortex mixer. The low pH and Ca(++) solubilize the transition region of the cilium and also prevent the cell from being disrupted. The cortices can be partially purified if the 600-g pellet is resuspended in 2.2 M sucrose pH 6.5 and centrifuged at 40,000 g for 2 h. Under these conditions, 85% of the nuclei form a pellet and the cortices float to the surface of the sucrose. In addition to the basal bodies or basal bodies with cilia, the cortices contain some adherent cytoplasm, a few fibers, and a few vesicles which may be remnants of mitochondria or endoplasmic reticulum. The structure of the cilia and the basal bodies isolated with either procedure is normal.

Heterogeneity of the alpha subunit of tubulin and the variability of tubulin within a single organism.

When tubulins obtained from particular microtubules of the sea urchin (ciliary doublet A tubules, flagellar doublet microtubules, and mitotic microtubules) are analyzed by electrophoresis in a polyacrylamide gel system containing sodium dodecyl sulfate and urea, heterogeneity of the alpha subunit, and differences between the tubulins are revealed. The alpha subunit of tubulin from mitotic apparatus and from A microtubules of ciliary doublets is resolved into two bands, while the alpha subunit of flagellar doublet tubulin gives a single band. The mitotic and ciliary tubulins differ in the mobilities of their two alpha species, or in the relative amounts present, or both. The existence of differences between the tubulins has been confirmed by a preliminary analysis of their cyanogen bromide peptides.

Release of intact microtubule-capping structures from Tetrahymena cilia.

The distal ends of ciliary microtubules are attached to the membrane by microtubule-capping structures. The capping structures are located at the sites of tubulin addition and loss in vivo and may be part of the regulatory system that directs ciliary and flagellar microtubule assembly. This study describes conditions for the release and stabilization of microtubule capping structures as a first step in their purification. Two types of capping structures, the distal filaments and the central microtubule caps, are selectively and independently released from the axoneme by CaCl2 and MgCl2 but not by MgSO4, ZnCl2, NaCl, KCl, or KI. The release of the caps and filaments is specific for Ca+2, Mg+2, and Cl- and is not simply a function of ionic strength. The capping structures are released without major disruption of the axonemal structure. In addition to providing a means to purify and identify the cap and filament components, these results suggest ways in which their binding to the axoneme may be modulated during periods of microtubule growth or shortening. This report also reveals that the distal filaments are composed of two separable components, a small bead inserted into the end of each A-tubule and a "Y"-shaped plug and filament that slips through the bead.

Localization of kinesin in cultured cells.

Kinesin was isolated from bovine brain and used to elicit polyclonal antibodies in rabbits. The specificities of the resulting antibodies were evaluated by immunoblotting. Antibodies purified from these sera by their affinity for brain kinesin react with a polypeptide of approximately 120 kD in extracts from bovine brain, PtK1 cells, and mouse neuroblastoma cells. They bind to a pair of polypeptides of approximately 120 kD present in crude kinesin prepared from Xenopus eggs and with a single polypeptide of approximately 115 kD in extracts from Drosophila embryos. Antibodies raised against kinesin prepared from fruit fly embryos (by W. M. Saxton, Indiana University, Bloomington, IN) and from neural tissues of the squid (by M. P. Sheetz, Washington University, St. Louis, MO) cross react with the mammalian, the fly, and the frog polypeptides. Kinesin antigen was localized in cultured cells by indirect immunofluorescence. PtK1 cells in interphase showed dim background staining of cytoplasmic membranous components and bright staining of a small, fibrous, juxtanuclear structure. Double staining with antibodies to microtubules showed that the fibrous object was usually located near the centrosome. On the basis of shape, size, and location, we identify the kinesin-positive structure as a primary cilium. PtK1 cells in mitosis are stained at their poles during all stages of division. The structure stained is approximately spherical, but wisps of faint fluorescence also extend into the body of the spindle. Antibodies to squid or fruit fly kinesin produce identical patterns in PtK1 cells. Controls with preimmune and preabsorbed sera show that the centrosome staining is not due simply to the common tendency of rabbit antisera to stain this structure. Similar centrosome and spindle pole staining was visible when antibodies to bovine brain or squid kinesin were applied to the A6 cell line (kidney epithelial cells from Xenopus laevis). Some possible functions of kinesin localized at the spindle poles are discussed.

Specific localization of scallop gill epithelial calmodulin in cilia.

Calmodulin has been isolated and characterized from the gill of the bay scallop aequipecten irradians. Quantitative electrophoretic analysis of epithelial cell fractions show most of the calmodulin to be localized in the cilia, specifically in the detergent- solubilized membrane-matrix fraction. Calmodulin represents 2.2 +/- 0.3 percent of the membrane-matrix protein or 0.41 +/- 0.5 percent of the total ciliary protein. Its concentration is at least 10(-4) M if distributed uniformly within the matrix. Extraction in the presence of calcium suggests that the calmodulin is not bound to the axoneme proper. The ciliary protein is identified as a calmodulin on the basis of its calcium- dependent binding to a fluphenazine-sepharose affinity column and its comigration with bovine brain calmodulin on alkaline-urea and SDS polyacrylamide gels in both the presence and absence of calcium. Scallop ciliary calmodulin activates bovine brain phosphodiesterase to the same extent as bovine brain and chicken gizzard calmodulins. Containing trimethyllysine and lacking cysteine and tryptophan, the amino acid composition of gill calmodulin is typical of known calmodulins, except that it is relatively high in serine and low in methionine. Its composition is less acidic than other calmodulins, in agreement with an observed isoelectric point approximately 0.2 units higher than that of bovine brain. Comparative tryptic peptide mapping of scallop gill ciliary and bovine brain calmodulins indicates coincidence of over 75 percent of the major peptides, but at least two major peptides in each show no near-equivalency. Preliminary results using ATP-reactivated gill cell models show no effect of calcium at micromolar levels on ciliary beat or directionality of the lateral cilia, the cilia which constitute the vast majority of those isolated. However, ciliary arrest will occur at calcium levels more than 150 muM. Because calmodulin usually functions in the micromolar range, its role in this system is unclear. Scallop gill ciliary calmodulin may be involved in the direct regulation of dyneintubule sliding, or it may serve some coupled calcium transport function. At the concentration in which it is found, it must also at least act as a calcium buffer.

Phosphonolipids: localization in surface membranes of Tetrahymena.

Approximately 60 percent of the phospholipids from the membrane sheath of Tetrahymena pyriformis cilia contain 2-aminoethylphosphonic acid. This is more than twice the concentration found in total cell lipids. The resistance of these lipids to hydrolytic enzymes suggests that they increase the stability of the surface membranes.

Studies of dynein from Tetrahymena cilia using agarose polyacrylamide gel electrophoresis.

Described in this report is an application of agarose-polyacrylamide gel electrophoresis, which separates protein components of crude dynein fraction (Fraction I by Gibbons) derived from Tetrahymena cilia. By this method, the fraction was separated into three protein components (designated as bands I, II and III) on the gel. When the gel was actively stained for dynein ATPase, a single band appeared, which coincided with the position of band I. A purified dynein prepared by controlled pore glass (CPG-10) column chromatography and followed by Biogel A-15m filtration showed one band on the gel at the same position as band I. These results suggest that among these three protein components, band I represents dynein and bands II and III are derived form non-ATPase protein. 'Burstic phenomenon' was also observed on their ATPase activity when axoneme or crude dynein fractions were used for ATPase assay, while the phenomenon was almost extinguished when partially purified dynein after controlled pore glass column chromatography was used as sample.

Purification and properties of dyneins from Paramecium cilia.

Dynein ATPases were purified from Paramecium cilia by salt extraction followed by sucrose density gradient centrifugation and anion exchange chromatography. The two major dyneins sedimented in sucrose gradients as species of 22 S and 12 S. After purification by anion exchange chromatography, their specific activities were about 0.4 and 0.5 mumol/min per mg, respectively. The dyneins could be distinguished by subunit composition and immunological crossreactivity. Sucrose density gradient centrifugation revealed additional ATPase activity in the region between the 22 S and 12 S dyneins, including a 19 S activity. Mg2+-ATPase activities of the dyneins and the 19 S activity were inhibited by vanadate and Zn2+, and were activated by Triton X-100. Antibodies against the 22 S dynein from Paramecium reacted on immunoblots with most of the polypeptides of 22 S dynein, and showed that the heavy chains of 22 S dynein are not identical to those that sediment at 19 S and 12 S. Several minor ATPase activities were revealed by anion exchange chromatography of fractions from the 22 S, 19 S and 12 S regions of sucrose gradients. These minor activities were stimulated by Mg2+, inhibited by vanadate, and could be distinguished from each other by their elution positions and polypeptide compositions.

Differential distribution of voltage-dependent calcium channels and guanylate cyclase in the excitable ciliary membrane from Paramecium tetraurelia.

A novel method for isolation of cilia and ciliary membrane vesicles from Paramecium tetraurelia has been developed. Using a continuous Percoll gradient of low osmolarity after fragmentation of purified cilia by French Press treatment two membrane fractions with different buoyant densities were obtained. These fractions were further purified by conventional discontinuous sucrose density gradients and characterized biochemically and by electron microscopy. Guanylate cyclase, a membrane bound enzyme, was found almost exclusively in membrane vesicles of high buoyant density while the voltage-sensitive calcium-channel of the ciliary membrane was predominantly localized in low density vesicles. Examination of both fractions by SDS polyacrylamide gel electrophoresis revealed only minor differences in protein pattern in the 34 and 64 kilodaltons range. Morphologically both membrane vesicle fractions had a diameter of about 300 nm, however, the high density vesicle fraction contained a considerably larger amount of multilamellar structures with a multishell, onion-like appearance. Freeze-fracture analysis failed to detect differences in intramembrane particle content between low and high density vesicles. The possible biological relevance of the spatial separation of the calcium-sensor enzyme guanylate cyclase and the voltage-sensitive calcium-channels in the ciliary membrane is discussed in terms of a diffusion controlled mechanism for graded signal transmission.

Identification of contractile proteins in basal bodies of ciliated tracheal epithelial cells.

To determine the molecular composition of the components of basal bodies and the interbasal body apparatus of ciliated cells in rat tracheal epithelium, we used rabbit anti-actin, anti-alpha-actinin, anti-tropomyosin, and anti-myosin as primary antisera applied to the tissue in an indirect immunoperoxidase technique. The antisera was proven to be monospecific by elution of antibody after affinity chromatography. Sheep anti-rabbit immunoglobulin Fab fragments coupled to peroxidase were used for ultrastructural localization of the bound rabbit antibody. Antibodies against alpha-actinin were demonstrated around peripheral microtubules of cilia and linking these microtubules to central doublet and plasma membrane. Alpha-actinin was also shown in the basal foot processes. Anti-actin antibodies were associated with microtubules of the cilium and basal bodies, except in the region of the ciliary necklace. The antibodies directed against actin also had affinity for rootlets, basal foot processes, and communications between basal bodies and foot processes. Both anti-myosin and anti-tropomyosin antibodies were localized to part of the region of the constriction of the cilium, to the central basal density and the outer surfaces of basal body microtubules, and to the basal foot processes together with their communications to the basal body. The data suggest active contractile function of basal bodies.

Monoclonal antibodies to ciliary glycoproteins of frog olfactory neurons.

Monoclonal antibodies were produced against isolated frog olfactory cilia, a preparation enriched in dendritic extensions of the chemosensory neurons. Two antibodies, 18.1 and 35.6, were found to react against specific glycoproteins of the sensory organelles. These glycoproteins were identified by their differential binding to the lectins wheat germ agglutinin and Concanavalin A. The antibodies fluorescently labeled isolated olfactory cilia, as well as the ciliary surface layer of olfactory epithelium, whose extent was defined by anti-tubulin and anti-keratin antibodies. Respiratory epithelium (or other tissues) as well as isolated respiratory cilia were not labeled by antibodies 18.1 and 35.6, indicating tissue specificity. The olfactory-specific antibodies can be used as markers of the sensory epithelium and of the sensory regions of olfactory dendritic membranes. Antibody 18.1 recognized gp95, a specific and major integral membrane glycoprotein of frog olfactory cilia. Since gp95 has been suggested as candidate olfactory receptor protein (Chen, Z. and Lancet, D., Proc. Natl. Acad. Sci. U.S.A., 81 (1984) 1859-1863), antibody 18.1 could also be useful for functional studies.

Immunohistochemical localization of fibronectin in the chinchilla cochlea.

The purpose of this study was to better understand the molecular composition of the cochlea. Fibronectin (FN), a well characterized adhesive glycoprotein, was localized by immunofluorescence microscopy in fresh and fixed cochlear tissues, and in fixed kidney tissue, using a polyclonal, affinity-purified, rabbit, anti-fibronectin antibody and a secondary antibody coupled to FITC. The FN antibody was free from cross-reactivity with other known basement membrane and cell matrix molecules. FN reactivity in the cochlea was most intense in the basilar membrane, latero-basal borders of Boettcher's cells, otic capsule, endothelial basement membranes (particularly those of the stria vascularis), and as a diffuse, fan-shaped network radiating into the spiral ligament. Little FN labelling was present in the epithelial basement membranes. Negative control tissue showed no immunoreactivity; whereas, positive kidney control tissue showed appropriate FN immunoreactivity in the mesangium of the glomerulus. The most significant finding of this study was that FN is a major component of the basilar membrane and its distribution appears to correspond to the amorphous ground substance. FN was not localized in the organ of Corti or at the tips of the hair-cell stereocilia.

The distribution of cationized ferritin receptors on ciliated epithelial cells of rat trachea.

The interaction of tracheal cilia with the biphasic mucus layer covering the surface of the mammalian respiratory tract may be influenced by many cell surface coat components including those having an overall negative charge. In order to assess the distribution of ciliary anionic sites, cationized ferritin (CF) was used to label the surface of rat tracheal epithelium. If pieces of trachea were fixed with 3% glutaraldehyde and treated with CF at low (L) (0.08 mg/ml), medium (M) (0.32 mg/ml PBS), or high (H) (0.64 mg/ml PBS) concentrations, the label was distributed evenly over the entire external surface of the ciliary membrane at all concentrations. Unfixed tracheal tissue was also treated with L, M, and H CF for 1 or 5 min at 4 degrees C in order to minimize lateral redistribution of CF receptors. To ensure accessibility of the cell surface to CF the samples were agitated thoroughly during exposure. Exposure for 1 min to L, M, and H CF resulted in a light binding of ferritin particles on all portions of the ciliary membrane with occasional areas of multilayered binding distributed randomly on the ciliary shaft. When unfixed trachea was treated with CF for 5 min at 4 degrees C, CF binding was similar except heavier and more uniform. In no instance was there any preferential binding of CF to the ciliary tips at any of the concentrations used. Moreover, as indicated by the CF binding pattern at L concentrations, high density negative charges are present over almost the entire surface of the cilium. These results suggest that, unlike the ciliary membrane of other organs such as oviduct, negatively charged cell surface coat molecules are present on all areas of the ciliary membrane of rat tracheal epithelia.