bluuebunny/crossref_metadata_2025 huggingface dataset:
Variations in thickness of articular cartilage in the human sacroiliac joint
Authors: Salsabili N. , Valojerdy M. R. , Hogg D. A.
Published: February 2005

Differences in articular cartilage thickness in the sacroiliac joint were investigated in different regions of the sacral and the iliac articular surfaces in the embalmed cadavers of five males and six females. The mean thickness of the sacral articular cartilage was greater than that of the iliac articular cartilage (P < 0.001) and the sacral articular cartilage of the female was thicker than that of the male (P < 0.02). Differences between thicknesses of the iliac articular cartilage in the male and female and in different regions of the sacral and iliac articular cartilages were found to be not significant. © 1995 WiIey‐Liss, Inc.
What future for dissection in courses of human topographical anatomy in universities in the UK?
Authors: Utting Matthew , Willan Peter
Published: February 2005

In the United Kingdom most medical schools have traditionally included dissection as a major component of their anatomy courses. There is a dearth of substantive literature which can be used to demonstrate the educational values of dissection, although many authors have expressed opinions. Current scrutiny of the role of dissection has been prompted by many influences acting on medical schools in the UK, including changes in the medical curriculum promoted by the General Medical Council, changes in the mechanisms of funding for universities and their courses, and the introduction of research assessments and appraisal of teaching. It is probable that in the UK dissection will continue to decline but that its reduced role will be prompted by the interactions of many complicated processes, only some of which will be educationally driven. © 1995 WiIey‐Liss, Inc.
The terminology of early development: History, concepts, and current usage
Authors: Collins P. , Billett F. S.
Published: February 2005

The meaning of some terms used in describing the development of embryos is discussed in the light of their historical origin and current usage. Attention is focused on the terminology associated with the early development of animals, particularly that concerned with gastrulation and germ layer theory. It is suggested that terms linked with outdated concepts are not always appropriate for, and unless defined with care may limit, our appreciation of the significance of subsequent observation and experiment. Recommendations are made concerning the use of the terms mesoblast, mesoderm and mesenchyme.
Structural and Magnetochemical Studies on KCuGaF6.
Authors: Dahlke P. , Pebler J. , Babel D.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Phase Diagram Studies of the Ti—Bi—Zn System.
Authors: Vassilev G. P. , Ishida K.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
An Electrochemical Investigation of Mg1‐xAlxNi (0 ≤ x ≤ 0.6) Hydrogen Storage Alloys.
Authors: Wang L. B. , Wang J. B. , Yuan H. T. , Wang Y. J. , Li Q. D.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Late‐Transition Metal Oxo Complex: K7Na9[O=PtIV(H2O)L2], L=[PW9O34]9‐.
Authors: Anderson Travis M. , Neiwert Wade A. , Kirk Martin L. , Piccoli Paula M. B. , Schultz Arthur J. , Koetzle Thomas F. , Musaev Djamaladdin G. , Morokuma Keiji , Cao Rui , Hill Craig L.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Rationally Designed Ligands for Asymmetric Iridium‐Catalyzed Hydrogenation of Olefins.
Authors: Kaellstroem Klas , Hedberg Christian , Brandt Peter , Bayer Annette , Andersson Pher G.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Novel Strategy for the Preparation of Arylhydroxylamines: Chemoselective Reduction of Aromatic Nitro Compounds Using Bakers′ Yeast.
Authors: Li Feng , Cui Jingnan , Qian Xuhong , Zhang Rong
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Reactive Dications: The Superacid‐Catalyzed Reactions of Alkynes Bearing Adjacent N‐Heterocycles or Amine Groups.
Authors: Klumpp Douglas A. , Rendy Rendy , Zhang Yun , McElrea Aaron , Gomez Alma , Dang Han
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Oxidation of 1,2‐Bis(cyanoalkyl)hydrazines to Azobisnitriles Using Trichloroisocyanuric Acid.
Authors: Mohite S. A. , Desai Uday V. , Pore D. M. , Mane R. B. , Wadgaonkar P. P.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Complementary Method to Obtain N‐Acyl Enamides Using the Heck Reaction: Extending the Substrate Scope for Asymmetric Hydrogenation.
Authors: Harrison Paul , Meek Graham
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Organocatalytic Asymmetric Hydroxylation of β‐Keto Esters: Metal‐Free Synthesis of Optically Active anti‐Diols.
Authors: Acocella Maria Rosaria , Mancheno Olga Garcia , Bella Marco , Joergensen Karl Anker
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Novel Fragmentation Reaction of 2‐Alkyl‐ and 2,4‐Dialkyl‐3‐iodo‐1‐oxocyclohexan‐2,4‐carbolactones.
Authors: Khim Seock‐Kyu , Dai Mingshi , Zhang Xuqing , Chen Lei , Pettus Liping , Thakkar Kshitij , Schultz Arthur G.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis, Antitubercular and Antimicrobial Activity of 6‐Carbethoxy‐5‐aryl‐3‐[p‐(3′‐chloro‐2′‐benzo [b]thiophenoylamino)phenyl]‐2‐cyclohexenones.
Authors: Kachhadia V. V. , Popat K. H. , Nimavat K. S. , Joshi H. S.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Powerful Aqueous Solvent Effect in an Intramolecular Diels—Alder Cyclization.
Authors: Kuhnert Nikolai , Sammes Peter G. , Smith Graham , Ward Robert W.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Tetrazolium N‐Aminides.
Authors: Moderhack Dietrich , Noreiks Matthias
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Novel and Facile Iodine(III)‐Mediated Approach for C(5)‐Acetoxylation of 6‐Hydroxyflavone and 6‐Hydroxyflavanones.
Authors: Prakash Om , Kaur Harpreet , Sharma Vijay , Bhardwaj Vikas , Pundeer Rashmi
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Properties of Water‐Repellent Cationic Surfactants.
Authors: Vissarionova O. N. , Temnikova S. A. , Ivanova N. V. , Voronchikhina L. I.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Green Preparation of Quinoline Derivatives Through FeCl3×6H2O Catalyzed Friedlander Reaction in Ionic Liquids.
Authors: Wang Jianji , Fan Xuesen , Zhang Xinying , Han Lijun
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Palladium‐Catalyzed Borylation of Phenyl Bromides and Application in One‐Pot Suzuki—Miyaura Biphenyl Synthesis.
Authors: Broutin Pierre‐Emmanuel , Cerna Igor , Campaniello Maria , Leroux Frederic , Colobert Francoise
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Novel Synthesis of Bis‐(α‐hydroxyalkyl)phosphinic Acids Involving Microwave Irradiation.
Authors: Kaboudin Babak , As‐habei Nasser
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Pseudopterosins P—V, New Compounds from the Gorgonian Octocoral Pseudopterogorgia elisabethae from Providencia Island, Colombian Caribbean.
Authors: Duque Carmenza , Puyana Monica , Narvaez Ginna , Osorno Oscar , Hara Noriyuki , Fujimoto Yoshinori
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Some 1,4‐Oxazepanes Fused with 1,6‐Anhydro‐β‐D‐hexopyranoses. 3,11,13‐Trioxa‐7‐azatricyclo[8.2.1.02,8]tridecane Derivatives.
Authors: Trtek Tomas , Cerny Miloslav , Trnka Tomas , Budesinsky Milos , Cisarova Ivana
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Iodine: A Versatile Reagent in Carbohydrate Chemistry. Part 16. Streamlined Synthesis of Per‐O‐acetylated Sugars, Glycosyl Iodides, or Thioglycosides from Unprotected Reducing Sugars.
Authors: Mukhopadhyay Balaram , Kartha K. P. Ravindranathan , Russell David A. , Field Robert A.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Mechanistic Studies of dUTPases
Authors: Kovari J. , Imre T. , Szabo P. , Vertessy B. G.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Non‐Radioactive Sensitive Assay to Measure 5‐Fluorouracil Incorporation into DNA of Solid Tumors
Authors: Noordhuis P. , Holwerda U. , Van Laar J. A. M. , Van der Wilt C. L. , Peters G. J.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Effect of Fluoropyrimidines on the Growth of Ureaplasma urealyticum
Authors: Wehelie Rahma , Eriksson Staffan , Wang Liya
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Cytotoxic and Apoptotic Effects of Novel Heterodinucleoside Phosphates Consisting of 5‐Fluorodeoxyuridine and Ara‐C in Human Cancer Cell Lines
Authors: Saiko P. , et al. et al.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Membrane Techniques
Authors: Bahrmann Helmut , Cornils Boy
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Lanthanoids in Aqueous‐Phase Catalysis
Authors: Kobayashi Shue
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Introduction of the Cyano Group by Substitution of Nitrogen Functions
Authors: Subramanian L. R.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Introduction of the Cyano Group by Substitution of a Halogen
Authors: Subramanian L. R.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Introduction of the Cyano Group by Substitution of Hydrogen
Authors: Schmidt A.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
A Fatal Affair: The Ubiquitinylation of Proteins
Authors: Biel Markus , Wascholowski Veit , Giannis Athanassios
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Recent Research Results in the Laboratory of Inorganic Chemistry of the University of Ioannina (Greece)
Authors: Hadjiliadis Nick
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Video‐enhanced contrast polarization (AVEC‐POL) microscopy: A new method applied to the detection of birefringence in the motile reticulopodial network of allogromia laticollaris
Authors: Allen Robert Day , Travis Jeffrey L. , Allen Nina Strömgren , Yilmaz HüSeyin
Published: February 2005

A new method is described for recording rapid processes of cell motility in polarized light. The Allen video‐enhanced contrast (AVEC‐POL) method of polarization microscopy achieves significant improvements in resolution, contrast, and the visibility of fine detail by a combination of novel adjustments to a standard (unrectified) polarizing microscope and video camera. Using the full working aperture of a high‐power planapochromatic objective lens and compensator setting of λ/9‐λ/4, visible images appear lacking in contrast. However, the same images viewed with an appropriate video camera equipped with an electronic offset adjustment can be made to appear with as much contrast as desired, revealing a significantly greater amount of fine detail in the image than can be seen by high extinction visual microscopy alone. At bias retardations between one‐ninth and one‐quarter wave, the diffraction anomaly observed near extinction disappears. Consequently, polarizing rectifiers are not required with the AVEC‐POL method, and images previously requiring photographic exposures of around 20 seconds are sufficiently bright to be registered on the video monitor in 1/60 second. Using an intensity monitor, quantitative measurements of cellular birefringence can be retrieved from live or videotaped images displaying a linear relationship between contrast and phase retardation due to birefringence. The AVEC‐POL method also renders accessible to polarized light analysis a number of objects that scatter or depolarize too much light to be studied by high extinction methods. The method is demonstrated on model objects and applied to the highly motile reticulopodial network of Allogromia laticollaris. Rapid motion in close association with microtubules can now be analyzed in greater detail at a significant reduction in the cost of recording.
The mechanochemical cycle of the dynein arm
Authors: Satir Peter , Wais‐Steider Jacobo , Lebduska Stephen , Nasr Anthony , Avolio Jock
Published: February 2005

A dynein arm attachment cycle produces sliding between adjacent doublet microtubules (N and N + 1) of cilia. In intact axonemes, in the absence of ATP, almost all arms appear attached at both ends (rigor). When ATP is added, most arms detach from doublet N + 1. In ATP and vanadate, the arms do not return to rigor, suggesting that ATP hydrolysis is required for re‐extension and reattachment of the dynein arm, but not for detachment. Using solutions containing dynein to decorate dynein‐less axonemal doublets, we confirm this interpretation. In the absence of ATP, both sides of each doublet decorate with arms. Addition of ATP, ATP and vanadate or AMP‐PNP causes immediate arm detachment, but only in the first instance, where extensive ATP hydrolysis can occur, does decoration eventually reappear. Dynein decorates heterologous axonemal doublets and brain microtubules, as well as homologous doublets, suggesting that this mechanochemical cycle may have general applicability in microtubule‐based cell motility.
The distribution of 10nm filaments and microtubules in endothelial cells during mitosis: Double‐label immunofluorescence study
Authors: Blose Stephen H.
Published: February 2005

I have used fluorescence microscopy and antibodies to 10nm filaments and tubulin labelled with contrasting fluorochromes to compare the distribution of these proteins in endothelial cells during cell division. During interphase the two filament systems have entirely different distributions: The bulk of the 10nm filaments form a ring that surrounds the cell center and nucleus and remains parallel to the substrate, while the microtubules radiate from the cell center to the cell's border. When the mitotic spindle replaces the radial microtubule pattern in mitosis, the spindle poles remain within—and in close proximity to—the ring of 10nm filaments. This was confirmed by electron microscopy which showed the ring and centrioles in the same plane separated by a distance of 300–400 nm.
Taxol induces microtubule assembly at low temperature
Authors: Thompson William C. , Wilson Leslie , Purich Daniel L.
Published: February 2005

Dissociated bovine brain microtubule protein has been shown to reassemble at 0°C in the presence of the drug taxol. Tubulin polymerization was monitored both by electron microscopy of the polymeric structures and by incorporation of tritiated GTP into filterable polymeric structures. Most of the labeled guanine nucleotide uptake into tubulin polymeric structures occurred in the first 30 minutes of incubation with the drug. The initial polymerization event results in the formation of protofilamentous tubulin ribbons. The first microtubules were noted after 1 hour of incubation with the drug. After 20 hours of incubation at 0°C with taxol, the bulk of the polymerized tubulin appeared to be in the form of microtubules. Cold‐stable tubulin rings with a mean diameter of 34 nm were present in the reaction mixture before the addition of taxol and throughout the 20‐hour incubation. Most of the rings were apparantly not involved in the taxol‐induced microtubule assembly. The results are consistant with a model whereby taxol induces an initial formation of protofilamentous ribbon structures, mostly from free tubulin dimers, and a slower subsequent folding of the ribbon structures into microtubules.
Dynein binding to microtubules containing microtubule‐associated proteins
Authors: Haimo Leah T. , Rosenbaum Joel L.
Published: February 2005

Microtubule‐associated proteins (MAPs), isolated from brain tubulin, bound to and saturated outer fibers of Chlamydomonas flagella. MAPs present on these microtubules prevented the subsequent recombination of dynein. MAPs also bound to intact axonemes and thus did not specifically bind to the dynein binding sites on the A subfiber. A molar ratio of 1 mole MAP2 per 27 moles tubulin dimers at saturation of the outer fibers with MAP2 suggested that MAPs could effectively interfere with dynein recombination only if the MAPs were near the dynein binding sites to sterically prevent binding. However, electron microscopic observations indicated that MAPs were not localized but, instead, were dispersed around the outer fibers. In addition, MAP2 present at saturating amounts on in vitro assembled brain microtubules had no significant effect on dynein binding. Dynein‐decorated microtubules contained clusters of arms suggesting that there may be cooperative interaction between the arms during dynein binding. Because the A subfiber of axonemes contains sites to which dynein preferentially attaches, MAPs may prevent recombination by interfering with cooperative binding to these specific sites. Dynein presumably binds with equal affinity to any protofilament on in vitro assembled microtubules, and, therefore, the MAPs may not be capable of effectively interfering with cooperative binding of dynein to these microtubules.
Microtubule‐dependent transport of secretory granules during stalk secretion in a peritrich ciliate
Authors: Suchard Suzanne J. , Goode Dennis
Published: February 2005

The role of microtubules in secretory granule translocation was studied during stalk secretion in the peritrich ciliate, Zoothamnium arbuscula. In each cell, the release of stalk‐forming secretory materials is restricted to a specialized region of the cytoplasm, the scopula. Many of the membrane‐bound secretory granules that dominate the scopular cytoplasm appear to be aligned along cortical microtubules that converge on the scopular surface. This arrangement is consistent with the hypothesis that microtubules transport granules relative to the sites of exocytosis. To establish the role of microtubules in stalk secretion, telotrochs were exposed to agents with different disruptive effects on microtubule function. Exocytosis itself is not prevented by these drugs, and granules positioned for secretion prior to treatment are released. Maytansine and isopropyl‐n‐phenyl carbamate (IPC) completely inhibit stalk elongation. In maytansine‐treated cells, microtubules are absent from the scopular cytoplasm, and granules are absent from the scopular surface. Microtubules are present in IPC‐treated cells, but the granules are misdirected to the cytoplasm lateral to the scopula where no secretory sites exist. Even though the rate of stalk secretion is decreased by deuterium oxide (D2O), a control length stalk is eventually produced. In D2O‐treated cells microtubules are present and in their normal orientation. The inhibition of secretion when microtubules are absent (maytansine) or misdirected (IPC) and the retardation of secretion when microtubule turnover is reduced (D2O) supports a mechanism of granule transport based on the directional turnover of microtubule subunits.
Regulation of calcium distribution in bovine sperm cells: Cytochemical evidence for motility control mechanisms
Authors: Nelson Leonard , Gardner Mary E. , Young Monica J.
Published: February 2005

Behavioral responses of mature spermatozoa treated with neurotropic factors suggest that calcium entry and intracellular transport may be regulated by a cholinergic mediated program. To test the validity of this proposed mechanism, the effect of several agents on Ca distribution in the sperm cell was examined cytochemically.

Sites of Ca accumulation were visualized in thin sections of bull spermatozoa by the application of a modification of Gomori's histochemical procedure for phosphatases. Intact bull sperm cells incubated at room temperature in a buffered balanced salt solution containing 5 mM/liter of CaCl2 showed small, randomly scattered deposits of the reaction product. Similarly treated sperm cells, plasmolyzed in hypoosmotic KCl, revealed a greatly increased amount of deposit associated with the cell membranes (mitochondrial surfaces and plasmalemma), the axonemal complex components, and satellite fibers adjacent to the outer dense fibers. Preincubation of intact cells in nicotine or eserine considerably enhanced the entry of calcium into the cell and its association with the membranes and other intracellular organelles. Decamethonium, an irreversible depolarizer and blocker of cholinergic receptors, interfered with the uptake and intracellular distribution of the calcium. Ouabain, the digitalis glycoside that decreases progressive motility of bull sperm and inhibits Na‐, K‐ATPase, appears to block Ca efflux, causing an intense accumulation of electron‐opaque particles in the plasma membrane while smaller numbers of particles are distributed sparsely throughout the cell interior.

The cytochemical results showing enhanced calcium entry in the presence of cholinergic agents, depressed intracellular calcium in cells treated with cholinergic receptor blocker, and intense accumulation of calcium within the cell membrane in the presence of ouabain are consistent with spermatozoan behavioral responses to these agents. These observations support the concept that neurotropic factors may be involved in regulating transmembrane and intracellular transport of ions in control of sperm cell function.
Evidence for nuclear membrane fluidity: Proacrosome migration and nuclear pore redistribution during grasshopper spermiogenesis
Authors: Troyer David , Schwager Petra
Published: February 2005

Electron microscopic examination of thin sections and freeze fractures of Locusta spermatids revealed that the proacrosome docks to the nuclear membrane and glides around the nucleus during sperm development. Whereas nuclear pore complexes occur in groups distributed at random over the entire nucleus of the early spermatid, they are found only in a narrow ring closely surrounding the centriolar adjunct in later spermatids. The pores appear to be swept caudally in the nuclear envelope, perhaps by a process like capping; they are not merely excluded by structures adhering to the nucleus. The observations suggest that both proacrosome migration and the deployment of pores are facilitated by the inherent fluidity of the nuclear membranes.
Site of Ca2+ action in triggering motility in the cyanobacterium spirulina subsalsa
Authors: Abeliovich Aharon , Gan Judith
Published: February 2005

Motility of the marine filamentous cyanobacterium Spirulina subsalsa is both Ca2+ and Na+ dependent, and replacement of Na+ by mannitol arrests it. The data presented suggest that Ca2+ interacts with sites on the surface of the cell membrane. The inhibitory effect of dicyclohexylcarbodiimide (DCCD) hints at the possibility that the role of Ca2+ may be associated with a membrane bound Ca‐ATPase. Motility is pH dependent, being nil at pH < 6.5 and > 10.0, with an optimum at 8.5. Norepinephrine abolishes most of the inhibitory effect of low pH on motility. Ca2+ has an “all‐or‐none” effect on motility that is triggered at 5 mM. Acetylcholine lowers the threshold of Ca2+ necessary for triggering motility.
Effects of infrared laser damage to the Euglena photoreceptor on the control of flagellar motility
Authors: Nichols Kathleen M. , Rikmenspoel Robert
Published: February 2005

When the area of the stigma of Euglena was irradiated with an infrared laser beam at a dose too low to cause permanent loss of motility, a reduction in flagellar motility was observed only when the external medium contained less than 1 mM Mg2+. At these low Mg2+ concentrations, the laser caused a decrease in flagellar frequency and a tendency for the flagellar waveform to shift towards that taken during reversed swimming. This suggests that the effect of the laser irrdiation was to deplete the cells of Mg2+. After the laser pulse the reversal response remained sensitive to the wavelength of the illuminating light. In white light (420–700 nm) 60% of the Euglena showed a reversed waveform; in orange light (530–700 nm) this increased to 90%. This shows that the photoreceptor was not destroyed by the laser irradiation.

These experiments were performed on cells that had been impaled on a microelectrode. If direct electric current was passed into the laser‐irradiated cells, the current necessary to cause flagellar arrest was 2 to 4 times less than that for cells not laser irradiated.

It is concluded that an internal Mg2+ store is present in the Euglena, localized in the area of the paraflagellar swelling; and that the laser irradiation eliminates this Mg2+ store, but at the power used it does not destroy the ability of the stigmaparaflagella to control the flagellar activity.
Motility of human polymorphonuclear neutrophils: Microscopic analysis of substrate adhesion and distribution of F‐actin
Authors: Sullivan J. A. , Mandell G. L.
Published: February 2005

Directed movement of polymorphonuclear neutrophils (PMN) requires cell polarization and the orderly making and breaking of cell‐substrate contacts. We compared the movement of human PMN suspended from the underside of glass coverslips to that of PMN seen in “profile” on fibers, using brightfield, differential interference contrast and reflection interference microscopy. Images were recorded on film and videotape and analyzed in real time and time lapse. The distribution of F‐actin was observed with image‐enhanced fluorescence microscopy after staining with NBD‐phallacidin.

PMN exhibited two patterns of motility. Fifteen to twenty‐five percent of cells moved in a low profile gliding pattern and exhibited cauded displacement of dorsal surface folds. Most PMN made progress by cycles of partial release of the lamellipodium from the substrate and anterior advance followed by arching or rolling and lamellipodial reassociation with the substrate. Cells stimulated with bacteria, casein, or chemotactic formyl peptide rarely spread on the coverglass but waved into the medium attached only by the uropod. Eventually, many detached completely from the substrate. Cells confined to the substrate surface with overlying agarose were able to locomote when confronted with these substances.

F‐actin was irregularly distributed in nonpolarized suspended cells but concentrated in the lamellipodium in polarized cells. As cells arched along a substrate, F‐actin accumulated in foci corresponding to the substrate‐PMN interface, particularly at the uropod and retraction fibrils. Conversely, cells that were physically restricted to movement in the plane of the substrate surface by overlying agarose exhibited diffuse F‐actin along the entire cell. Suspended PMN polarized with formyl peptide and incubated with Con A accumulated F‐actin at the uropod. These observations suggest that both PMN locomotion and the movement of Con A binding sites involve the caudad redistribution of F‐actin.
Microtubule‐containing detergent‐extracted cytoskeletons in sea urchin eggs from fertilization through cell division: Antitubulin immunofluorescence microscopy
Authors: Balczon Ron , Schatten Gerald
Published: February 2005

The microtubule‐containing structures that appear in eggs during fertilization and cell division in the sea urchins Lytechinus variegatus and Arbacia punctulata were detected by antitubulin immunofluorescence microscopy of detergent extracted cytoskeletal preparations. The extraction buffer, which is composed of 0.55 mM MgCl2, 10 mM EGTA, 25 mM MES, 25% glycerol, 1% Nonidet P‐40, and 25 μM PMSF, pH 6.7, allows for dramatically improved fluorescent images compared to those obtained using conventional staining procedures, with residual background staining being reduced to near zero.

The immunofluorescent images obtained using this technique provide information on several motile events that occur during the first cell cycle. This technique demonstrates that all of the cytoplasmic microtubules are associated with the incorporated sperm's centrioles during female pronuclear migration. This changes during the centration of the male and female pronuclei at which time a monastral array of microtubules forms in the egg's cytoplasm. A large proportion of the monastral microtubules do not appear to be associated with the centrioles. At prophase and early metaphase, the centrioles are the dominant microtubule organizing centers (MTOCs) consistent with mitotic theories that the kinetochore catches, but does not initiate, microtubules. Observations of intercentriolar distances show that there are three stages of pole separation during the first cell cycle. The initial separation occurs during pronuclear centration, the second during the streak stage, and the final one during the late stages of mitosis. At telophase, polar microtubules appear to extend into the cortex supporting the cell surface at all regions except the presumptive cleavage site.
Chromosome movement during meiotic prophase in crane‐fly spermatocytes. II. Analysis of polarization of chromosomes and their association with the nuclear envelope
Authors: LaFountain James R.
Published: February 2005

Association of bivalent chromosomes with the astral centers and nuclear envelope was analyzed in crane‐fly spermatocytes during the final hours of diakinesis. In contrast to other systems in which movement of chromosomes during diakinesis correlates with the clustering of bivalents near the astral centers, such clustering is not prevalent in crane‐fly spermatocytes. Polarization indices of bivalents calculated 5 to 10 minutes before the end of diakinesis provided evidence for polarization of only a fraction of all bivalents. Similar results were obtained in a large number of fixed cells in which asters and chromosomes were preferentially stained. Ultrastructural analysis of cells in late diakinesis revealed significant contact between bivalents and the nuclear envelope in all 46 cells that were analyzed. The extent of contact in some cells was greater than in others. Sites of contact included the telomeric ends of bivalents, and in some cases the distribution of contact sites suggested the possible involvement of centromeres in chromosome‐nuclear envelope association. The results are consistent with the hypothesis that a dynamic interaction between chromosomes and nuclear envelope may exist during late prophase, when the movement of chromosomes is known to occur.
Mitochondrial motility in axons: Membranous organelles may interact with the force generating system through multiple surface binding sites
Authors: Martz Dean , Lasek Raymond J. , Brady Scott T. , Allen Robert D.
Published: February 2005

In living tissue, membrane‐bound organelles, including mitochondria, move along parallel cytoplasmic pathways. Motion is directed and tends to be confined to a single path. Deviations from this single path motion are rare. When present, however, they tend to occur at points of intersection of cytoskeletal linear elements (LE). Such intersections are relatively uncommon in intact axons and extruded axoplasm. However, we have found that such intersections can be produced in extruded preparations by shear forces directed tangential to the axoplasmic surface.

We have studied the detailed behavior of mitochondria in extruded squid axoplasm. Special attention was directed to the relationship between mitochondrial shape changes and orientation of cytoskeletal LE. The most striking of these changes in shape is branching. In this process, the mitochondrion transiently assumes a triradial (three‐ended) shape. This appearance may be maintained for seconds to minutes before the normal cylindrical shape is resumed by absorption of either the newly formed end or, more commonly, one of the original ends. The frequency of branching appears to be dependent on the degree of cytoskeletal organization. It becomes more common as the number of apparent intersections between cytoskeletal LE increases. Further, the formation of new ends seems to occur along paths defined by cytoskeletal elements.

These observations suggest that the mitochondrial membrane is multivalent. That is, it contains multiple sites capable of interacting with the axonal force generation apparatus. Furthermore, LE in the cytoskeleton may indicate the paths along which these interactions are permissible.
Nucleotide specificity for reactivation of organelle movements in permeabilized axons
Authors: Forman David S. , Brown Kurt J. , Promersberger Mark W. , Adelman Mark R.
Published: February 2005

In a permeabilized axon model, exogenous ATP can reactivate intraaxonal saltatory organelle movements (microscopically visible manifestations of fast axonal transport). We have studied the dependence of the reactivated movements on the ATP concentration and have also examined the nucleotide specificity of the reactivation. Organelle transport was visualized in isolated lobster giant motor axons using Nomarski optics and video microscopy. The axons were permeabilized with saponin, and movement was reactivated with ATP or other nucleotides. Some slight movement was seen with ATP concentrations as low as 10 μM. The velocity and frequency of the reactivated transport increased with increasing ATP concentrations up to about 5 mM. Movement was also reactivated by deoxyadenosine triphosphate, but not by AMP–PNP (a nonhydrolyzable ATP analogue), ADP, or AMP. Although other nucleotides (CTP, GTP, UTP, ITP) could reactivate transport, movement equivalent to that produced by 0.1 mM ATP was only seen with tenfold or greater concentrations of the other nucleotides. This pattern of specificity is consistent with the hypothesis that a dynein‐like ATPase, rather than a myosin, is involved in fast axonal transport.
Trifluoperazine‐induced changes in swimming behavior of paramecium: Evidence for two sites of drug action
Authors: Otter Tim , Satir Birgit H. , Satir Peter
Published: February 2005

Trifluoperazine (TFP), a drug that binds to Ca2+‐calmodulin (CaM) complexes, altered swimming behavior not only in living paramecia, but also in reactivated, Triton‐extracted “models” of the ciliate. By comparing the responses of living cells and models, we have ascertained that two sites of drug action exist in paramecium cilia. Swimming movements were recorded in darkfield stroboscopic flash photomicrographs; this permitted accurate quantitation of velocities and body‐shape parameters. When living paramecia were incubated in a standard buffer containing 10 μM TFP, their speed of forward swimming fell over several minutes and their bodies shortened. Untreated paramecia backed up repeatedly and frequently upon transfer to a solution containing barium ions (the “barium dance”), but cells preincubated in TFP did not “dance.” Instead they swam forward slowly for long periods of time without reversing and occasionally then exhibited abnormally prolonged reversals. W7 effects on swimming mimicked low doses of TFP, and the analog W5 did not visibly alter normal swimming patterns. These results suggest that TFP induces a decrease in the intracellular pCa of living paramecia, perhaps by reducing the efficiency of a calmodulin‐activated calcium pump in the cell membrane. Paramecia extracted with Triton X‐100 and reactivated to swim forward (7 ≥ pCa ≥ 6) were not affected by addition of up to 40 μM TFP to the reactivation medium. We conclude that the main drug effect in living cells is probably not at the axoneme. However, at low pCa, TFP directly affected the ciliary axoneme to shift its behavior to one characteristic of a higher pCa: TFP inhibited backward swimming in models reactivated at pCa < 6; instead they swam forward or rocked in place. The mechanism of ciliary reversal in paramecium may therefore depend on an axonemal Ca+‐sensor, possibly bound CaM, which is affected by TFP only at low pCa, as has been postulated for other types of cilia.
Differential distribution and function of microtubules and microfilaments in sea urchin coelomocytes
Authors: Edds Kenneth T.
Published: February 2005

Sea urchin coelomocytes were used as a model system to investigate the distribution and role of microtubules and microfilaments in cell spreading and filopodial formation. By using immunoblot characterized antisera to tubulin and actin coupled with immunofluorescence techniques, cellular protrusions were seen to contain actin filaments but no microtubules. Cells depleted of MT's by cold and colcemid treatments could attach, spread, and transform to the filopodial morphology normally.
Mechanics of cytogels I: Oscillations in Physarum
Authors: Oster G. F. , Odell G. M.
Published: February 2005

The contractility of actomyosin gels is the basis for a variety of cellular motility phenomena. We present here a mechanical analysis of contractile gels. By making certain hypotheses on the chemical regulation of cytogel contraction we formulate a model for the rhythmic contractions of plasmodia in the slime mold Physarum polycephalum which is in accord with a number of experimental observations.
The locomotion of dissociated sponge cells: A cell‐by‐cell, time‐lapse film analysis
Authors: Gaino Elda , Zunino Lidia , Burlando Bruno , Sarà Michele
Published: February 2005

The production of both lamellipodia and peculiar thin protuberances (scleropodia) characterizes the preaggregative motility of cells after dissociation of the sponge Clathrina.

The locomotory paths taken by cells before aggregation were recorded by time‐lapse microcinematography. Changes of direction in successive 50‐s time intervals and 50‐s mean velocities of each cell were both taken into account as statistical variables. Their distributions give probability density curves that seem to fit bilateral exponential functions. The analysis of the angles of turn indicates a tendency for the cells to persist in their direction of motion and to make counter‐clockwise turns. Implications of such in vitro cellular behaviors in aggregative and in vivo processes are suggested.
An approach to digital image analysis of bending shapes of eukaryotic flagella and cilia
Authors: Baba Shoji A. , Mogami Yoshihiro
Published: February 2005

A novel method of digital image analysis of the bends of eukaryotic flagella and cilia was devised. In the analysis system, all image pixels were systematically extracted and processed to measure angular direction and curvature. Simulation experiments on theoretical model pictures of flagella with sine‐generated or arcstraight line bending waves demonstrated that the method can be used with considerable high accuracy. This method then revealed abrupt changes in slope of the curvature in sperm flagella and embryo cilia of the sea urchin, Hemicentrotus pulcherrimus. This indicates that the digital image processing used may be helpful in the study of flagellar and ciliary movements.
A model for fast axonal transport
Authors: Blum J. J. , Reed M. C.
Published: February 2005

A model for fast axonal transport is developed in which the essential features are that organelles may interact with mechanochemical cross‐bridges that in turn interact with microtubules, forming an organelle‐engine‐microtubule complex which is transported along the microtubules. Computer analysis of the equations derived to describe such a system show that most of the experimental observations on fast axonal transport can be simulated by the model, indicating that the model is useful for the interpretation and design of experiments aimed at clarifying the mechanism of fast axonal transport.
Regulation of ciliary motility by membrane potential in Paramecium: A role for cyclic AMP
Authors: Bonini Nancy M. , Gustin Michael C. , Nelson David L.
Published: February 2005

The membrane potential of Paramecium controls the frequency and direction of the ciliary beat, thus determining the cell's swimming behavior. Stimuli that hyperpolarize the membrane potential increase the ciliary beat frequency and therefore increase forward swimming speed. We have observed that (1) drugs that elevate intracellular cyclic AMP increased swimming speed 2–3‐fold, (2) hyperpolarizing the membrane potential by manipulation of extracellular cations (e.g., K+) induced both a transient increase in, and a higher sustained level of cyclic AMP compared to the control, and (3) the swimming speed of detergent‐permeabilized cells in MgATP was stimulated 2‐fold by the addition of cyclic AMP. Our results suggest that the membrane potential can regulate intracellular cAMP in Paramecium and that control of swimming speed by membrane potential may in part be mediated by cAMP.
Regulation of cell motility, morphology, and growth by sulfated glycosaminoglycans
Authors: Klebe Robert J. , Escobedo Laura V. , Bentley Kevin L. , Thompson Laura K.
Published: February 2005

Due to the recent observation that heparin binds to several growth factors and cell adhesion molecules, the effect of heparin on biological processes governed by growth factors and cell adhesion molecules was investigated. Pharmacological doses of heparin were found to alter cell growth rate, cellular morphology, and cell motility.

Concentrations (μg/ml) of heparin or dextran sulfate decreased cell growth rate, but not the final cell density attained in plateau phase. The effect of heparin on cell growth rate was most pronounced when cells were cultured in low concentrations of serum. A heparin‐induced decrease in cell growth rate could be reversed by addition of platelet‐derived growth factor (PDGF), a heparin‐binding growth factor.

Heparin altered the morphology of all cell lines studied to various degrees. The effect of heparin on cell morphology was quantitated by measuring the heparin‐induced change in cell surface area. HT‐1080 and HeLa cells nearly doubled in surface area upon exposure to 10μg/ml heparin. Since several heparin‐binding cell adhesion proteins mediate both cell spreading and cell migration, the influence of heparin on cell migration was investigated with an improved version of the phagokinetic track technique. Low concentrations of heparin and dextran sulfate were found to increase the rate of cell migration in a dose‐dependent fashion.

Since the quantitative effect of heparin on cell growth rate, morphology, and migration depends on the cell line studied, it is suggested that three separate phenomena may be involved. The results presented indicate a central role for sulfated glycosaminoglycans in the control of both cell growth and cell‐cell interactions.
Influence of translocation track on the motion of intra‐axonally transported organelles in human nerve
Authors: Lynn Marc P. , Atkinson Mark B. , Breuer Anthony C.
Published: February 2005

The mechanism by which organelles are transported bidirectionally in axoplasm is still unknown; however, evidence of a key role for microtubules in many nonmammalian models has been established. We have observed common or shared tracks within the axoplasm of human nerves along which multiple organelles of varying size and shape are bidirectionally transported. Organelles traveling anterogradely and retrogradely were visualized by video‐enhanced differential interference contrast optics and analyzed with the aid of computer‐image‐processing techniques.

Speeds of translocating organelles were determined at eight to 16 translocation points along a path or “track.” Each translocation speed was plotted against its corresponding position on the track to develop a “speed/position diagram.” Regardless of mean organelle speed or direction of motion, organelles sharing a common track exhibited similar patterns of “speeding up” and “slowing down” relative to position along the track. Speed position data for organelles translocating the local axonal region of a common track showed no unique patterns (not different from a uniform distribution, p < 0.05). The unique speed/position patterns exhibited by common tracks were not necessarily related to the patterns of other tracks in the immediate vicinity (distance between tracks of < 0.50 μm). These findings suggest that (1) there are “common tracks” shared by organelles moving retrogradely and anterogradely; (2) both the organelles and the “track” associated with its translocation play a role in the resultant motion of that organelle; (3) the influence exerted by a common track on the motion of an organelle results in a pattern of speed changes related to position along the track.
Evidence for an interaction between the cell surface and intermediate filaments in cultured fibroblasts
Authors: Green Kathleen J. , Goldman Robert D.
Published: February 2005

Intermediate filaments (IF) were found in close proximity to the plasma membrane in substrate attached baby hamster kidney cells (BHK‐21) and chick embryo fibroblasts (CEF) as well as cells removed from their substrate in the absence of trypsin. However, in cells removed with trypsin, it appeared that IF had retracted away from the membrane. In cells with abundant extracellular matrix (ECM), colchicine induced massive cables of IF, which appeared to interact with specialized areas of the inner plasma membrane. In cells lysed to extract most microfilaments and cytoplasmic constituents, the intact IF network which remained was closely associated with the ECM. From these ultrastructural observations it was concluded that IF interact in some way with a “cell membrane complex” defined as comprising the plasma membrane and molecules attached to its inner and outer surfaces.

In order to investigate the possibility that components of the membrane complex may co‐isolate with IF, native intermediate filaments (NIF) were prepared. In addition to the structural subunits and other associated polypeptides, a ∼220 kd species which reacted specifically with antibodies directed against the ECM protein fibronectin (FN) was observed; 220 kd was still present after NIF were isolated under pH conditions where FN is more soluble, suggesting that its presence was not simply due to the coprecipitation of two insoluble proteins. Immunofluorescence and immunogold localization confirmed that FN is a component of the cell membrane complex with which IF appeared to interact.
Rhamnolipid from Pseudomonas aeruginosa inactivates mammalian tracheal ciliary axonemes
Authors: Hastie A. T. , Hingley S. T. , Higgins M. L. , Kueppers F. , Shryock T.
Published: February 2005

Isolated ciliary axonemes from pig trachea were exposed to increasing concentrations of purified Pseudomonas aeruginosa rhamnolipid. This is a defined ciliary system allowing observation of direct impairment of functional axonemes. Axonemal motility and ATPase activity were decreased in proportion to rhamnolipid concentrations. ATPase‐associated proteins observed in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and dynein arms seen in ultrastructural cross sections progressively disappeared from axonemes with exposure to rhamnolipid. These four independent measures establish that the rhamnolipid removes the ATPase‐containing outer dynein arms from the ciliary axoneme, thereby rendering the axoneme immotile.