bluuebunny/crossref_metadata_2025 huggingface dataset:
Atrial veins of the human heart
Authors: Von Lüudinghausen Michael , Ohmachi Nobuko , Besch Stephan , Mettenleiter Reas
Published: February 2005

Modern anatomical description divides the cardiac veins into two groups: tributaries of the greater cardiac vascular system (GCVS) and tributaries of the smaller cardiac vascular system (SCVS), consisting of the Thebesian vessels. Both systems intercom municate extensively. With the exception of the oblique vein of the left atrium (Marshall's vein), veins draining the walls of both the left and right atrium have not been well illustrated or described in anatomical atlases and textbooks. Consequently, we do not know exactly to which of the two groups (GCVS or SCVS) the atrial veins belong. There are three groups of left atrial veins: (1) tributaries of the left coronary vein and the coronary sinus; (2) special veins draining the right‐sided walls of the left atrium that terminate via intramural sinuses in the right atrium, which vessels occur in 92% of cases and belong to the GCVS; (3) in 81% of cases special veins drain the myocardium of the posterior and superior walls of the left atrium. In most cases they empty into the left atrium itself; in almost 40% of the cases they are connected with mediastinal veins. These veins, also belonging to tributaries of the GCVS, constitute a distinctly separate category of cardiac veins and should be designated proper veins of the left atrium. The veins draining the walls of the right atrium fall also into three groups: (1) In most cases there are short or large intramural tunnels or sinuses in the basic walls of the auricle and atrioventricular node area. The generally valveless openings of all the venous tunnels and sinuses are lined up on a circle just above the tricuspid valve and between the openings of both venae cavae. (2)There are also thin veins at the junction of the right atrium with both the superior and inferior vena cava. (3) In addition, there are numerous cardiac veins of the “smallest size” (real Thebesian veins). © 1995 WiIey‐Liss, Inc.
Arterial embolism from anatomical variation at the thoracic outlet
Authors: Dovgan Peter S. , Edwards John D. , Ayoub Magi T. , Horpe Patricia T , Agrawal Devendra K.
Published: February 2005

Thoracic outlet syndrome (TOS) represents a constellation of symptoms arising from the compression of the neurovascular bundle as it exits the thorax. We report a unique case of multiple rare anatomical anomalies resulting in TOS manifested by distal arterial embolism. These anomalies include the combination of: (1) a unilateral right cervical rib, Gruber's type II (Gruber 1869), (2) nonunion of the first thoracic rib, (3) abnormal fibrous insertions of the anterior scalene muscle onto the epineurium of the brachial plexus and adventitia of the subclavian artery, (4) anterior position of the brachial plexus in relation to the third portion of the subclavian artery, and (5) the bifurcation of a single root of the phrenic nerve at the level of the anterior scalene muscle. This series of findings suggest an underlying developmental abnormality with a delayed onset of symptomatology consisting of the thoracic outlet syndrome. © 1995 WiIey‐Liss, Inc.
The anatomy of left bronchus syndrome
Authors: Ashour M.
Published: February 2005

This explanation of the previously described left bronchus syndrome (Ashour et al., 1990, Thorax, 45:210–212) is based on a prospective study of 17 additional cases with unilateral lung destruction. It is likely that the anatomic peculiarities of the left main bronchus predispose the left lung to more frequent bronchial obstruction and hemodynamic changes than the right. Broncho‐pulmonary shunt formation and retrograde filling of the pulmonary artery most likely lead to increased oxygen tension and impaired lymph flow in the entire lung, thus spreading tuberculosis in the lung and ultimately leading to left lung destruction. © 1995 WiIey‐Liss, Inc.
The sympathetic innervation of the eyes and face: A clinicoanatomic review
Authors: Watson Craig , Vijayan Nazhiyath
Published: February 2005

Most of the details regarding the course of the sympathetic fibers to human ocular structures are based on anatomical and physiological studies in lower animals. While studying a clinical problem involving pericarotid sympathetic fibers, it became obvious that these animal observations cannot adequately explain the findings in human diseases affecting these pathways. An attempt was made, therefore, to clarify this situation.

We were able to gather enough information from human clinical and experimental studies, from our own clinical observations, and from our cadaver dissections to conclude that these pathways are somewhat different from those which are usually described in the literature. Based on this information, we conclude that (1) the oculosympathetic fibers in man do not course through the tympanic plexus and/or trigeminal ganglion, and (2) the sweat glands of the face receive their innervation from both internal and external carotid sympathetic plexuses. We also have suggestive, but inconclusive, evidence regarding the final mode of distribution of these fibers to the dilator of the pupil and the smooth muscle portion (deep layer) of the levator palpebrae superioris muscle (superior tarsal muscle). © 1995 WiIey‐Liss, Inc.
The size of the anterior spinal artery in relation to the arteria medullaris magna anterior in humans
Authors: Zhang Tao , Harstad Lynn , Murray Michael J. , Parisi Joseph E.
Published: February 2005

We studied the anterior spinal artery (ASA) in 25 cadaveric human spinal cords to determine the cross‐sectional area of the ASA cephalad and caudal to the entry of the arteria medullaris magna anterior (AMMA). Spinal cords were removed en bloc and latex was injected into the AMMA. The preparations were then fixed in formalin, embedded in paraffin, sectioned, mounted, and stained with hematoxylin and eosin. The diameter and cross‐sectional area of the ASA 1 cm above and 1 cm below the entry of the AMMA were measured. The mean radius of the ASA above the entry of AMMA was 0.14 ± 0.03 mm compared to 0.28 ± 0.05 mm below the entry of the AMMA (P < 0.001). According to Poiseuille's equation, the resistance to blood flow in the ASA cephalad to the AMMA would be 14.8 times greater than the resistance to blood flow caudal to the ANIMA. This resistance could affect the distribution of blood flow in the distal spinal cord whenever flow in the AMMA or distal ASA is altered. © 1995 WiIey‐Liss, Inc.
Styloid chain ossification: Report of a case with articulations
Authors: Kiely Michael L. , Sawyer Danny R. , Gowgiel Joseph M.
Published: February 2005

A bilateral ossified stylohyoid ligament was observed in a cadaver specimen. On the left side, the stylohyoid chain was markedly enlarged. The stylohyoid ligament was completely ossified into two segments separated by a diarthrodial‐like joint. An articulation was also observed between the enlarged styloid process and the ossified ligament. On the right side, the styloid process had a normal appearance. The middle part of the stylohyoid ligament was ossified and it was attached to the styloid process and to the hyoid bone by a fibrous band. Proposed theories to account for the ossification oaf this ligament are discussed. Since the presence of an enlarged and ossified stylohyoid chain can cause much discomfort and pain, a greater understanding of the causative factors responsible for this anomaly is needed to provide for more effective diagnosis and treatment. © 1995 WiIey‐Liss, Inc.
The official nomenclature of the superficial veins of the lower limb: A case for revision
Authors: Staubesand J. , Li Y. , Steel F.
Published: February 2005

Attention is called to the discrepancy which exists between the official terminology of the Nomina Anatomica (PNA) as it relates to the superficial venous system of the lower limb, and anatomical reality. Suggestions are also put forward as to how the PNA could be altered to accord better with the systematic classification and topography of these vessels, and more usefully serve the needs of clinicians. © 1995 WiIey‐Liss, Inc.
Aspects of Glycosidic Bond Formation in Aqueous Solution: Chemical Bonding and the Role of Water
Authors: Stubbs John M. , Marx Dominik
Published: February 2005

A model of the specific acid‐catalyzed glycosidic bond formation in liquid water at ambient conditions is studied based on constrained Car–Parrinello ab initio molecular dynamics. Specifically the reaction of α‐D‐glucopyranose and methanol is found to proceed by a DNAN mechanism. The DN step consists of a concerted protonation of the O1 hydroxyl leaving group; this process results in the breaking of the C1O1 bond, and oxocarbenium ion formation involving C1O5. The second step, AN, is the formation of the C1Om glycosidic bond, deprotonation of the methanol hydroxyl group OmHm, and re‐formation of the C1O5 single bond. A focus of this study is the analysis of the electronic structure during this condensed phase reaction relying on both Boys/Wannier localized orbitals and the electron localization function ELF. This analysis allows the clear elucidation of the chemical bonding features of the intermediate bracketed by the DN and AN steps, which is a non‐solvent equilibrated oxocarbenium cation. Most interestingly, it is found that the oxygen in the pyranose ring becomes “desolvated” upon double bond/oxocarbenium formation, whereas it is engaged in the hydrogen‐bonded water network before and after this period. This demonstrates that hydrogen bonding and thus the aqueous solvent play an active role in this reaction implying that microsolvation studies in the gas phase, both theoretical and experimental, might lead to qualitatively different reaction mechanisms compared to solution.
Assembly of a Series of Malarial Glycosylphosphatidylinositol Anchor Oligosaccharides
Authors: Kwon Yong‐Uk , Soucy Regina L. , Snyder Daniel A. , Seeberger Peter H.
Published: February 2005

We report an efficient and convergent synthesis of a series of oligosaccharides comprised of the malaria GPI glycan (2 a), a promising anti‐malaria vaccine candidate currently in preclinical trials and several related oligosaccharide sequences (3–8) that are possible biosynthetic precursors of the malarial GPI. A flexible synthetic strategy is disclosed that relies on a late‐stage coupling between oligomannosides of varying length and pseudo‐disaccharide glycosyl acceptor 11 to readily access various malarial GPI structures. Phosphorylation was accomplished by mild and efficient H‐phosphonate chemistry before the final deprotection was carried out by using sodium in ammonia. The direct connection of a thiol group via a phosphate diester linkage to the inositol moiety provides a handle for easy conjugation of the GPI glycan to carrier proteins, immobilization on carbohydrate microarrays and photo‐affinity labels identification. These synthetic oligosaccharides will serve as molecular probes.
An OsII–Bisbipyridine–4‐Picolinic Acid Complex Mediates the Biocatalytic Growth of Au Nanoparticles: Optical Detection of Glucose and Acetylcholine Esterase Inhibition
Authors: Xiao Yi , Pavlov Valeri , Shlyahovsky Bella , Willner Itamar
Published: February 2005

The complex OsII–bisbipyridine–4‐picolinic acid, [Os(bpy)2PyCO2H]2+ (1), mediates the biocatalyzed growth of Au nanoparticles, Au NPs, and enables the spectroscopic assay of biocatalyzed transformations and enzyme inhibition by following the Au NP plasmon absorbance. In one system, [Os(bpy)2PyCO2H]2+ mediates the biocatalyzed oxidation of glucose and the growth of Au NPs in the presence of glucose oxidase, GOx, AuCl4−, citrate and Au NP seeds. The mechanism of the Au NPs growth involves the oxidation of the [Os(bpy)2PyCO2H]2+ complex by AuCl4− to form [Os(bpy)2PyCO2H]3+ and AuI. The [Os(bpy)2PyCO2H]3+ complex mediates the GOx biocatalyzed oxidation of glucose and the regeneration of the mediator 1. Citrate reduces AuI and enlarges the Au seeds by the catalytic deposition of gold on the Au NP seeds. In the second system, the enzyme acetylcholine esterase, AChE, is assayed by the catalytic growth of the Au NPs. The hydrolysis of acetylcholine (2) by AChE to choline is followed by the [Os(bpy)2PyCO2H]3+ mediated oxidation of choline to betaine and the concomitant growth of the Au NPs. The mediated growth of the Au NPs is inhibited by 1,5‐bis(4‐allyldimethylammonium‐phenyl)pentane‐3‐one dibromide (3). A competitive inhibition process was demonstrated (KM=0.13 mM, KI=2.6 μM) by following the growth of the Au NPs.
Synthesis of Functionalized Rab GTPases by a Combination of Solution‐ or Solid‐Phase Lipopeptide Synthesis with Expressed Protein Ligation
Authors: Brunsveld Luc , Watzke Anja , Durek Thomas , Alexandrov Kirill , Goody Roger S. , Waldmann Herbert
Published: February 2005

Prenylated proteins with non‐native functionalities are generally very difficult to obtain by recombinant or enzymatic means. The semisynthesis of preparative amounts of prenylated Rab guanosine triphosphatases (GTPases) from recombinant proteins and synthetic prenylated peptides depends largely on the availability of functionalised prenylated peptides corresponding to the proteins' native structure or modifications thereof. Here, we describe and compare solution‐phase and solid‐phase strategies for the generation of peptides corresponding to the prenylated C terminus of Rab7 GTPase. The solid‐phase with utilisation of a hydrazide linker emerges as the more favourable approach. It allows a fast and practical synthesis of pure peptides and gives a high degree of flexibility in their modification. To facilitate the analysis of semisynthetic proteins, the synthesised peptides were equipped with a fluorescent group. Using the described approach, we introduced fluorophores at several different positions of the Rab7 C terminus. The position of the incorporated fluorescent groups in the peptides did not influence the protein‐ligation reaction, as the generated peptides could be ligated onto thioester‐tagged Rab7. However, it was found that the positioning of the fluorescent group had an influence on the functionality of the Rab7 proteins; analysis of the interaction of the semisynthetic Rab7 proteins with REP (Rab escort protein) and GDI (guanosine diphosphate dissociation inhibitor) molecules revealed that modification of the peptide side chains or of the C‐terminal isoprenoid did not significantly interfere with complex formation. However, functionalisation of the C terminus was found to have an adverse effect on complex formation and stability, possibly reflecting low structural flexibility of the Rab GDI/REP molecules in the vicinity of the lipid‐binding site.
Water‐Insoluble Ag–U–Organic Assemblies with Photocatalytic Activity
Authors: Yu Zhen‐Tao , Liao Zuo‐Lei , Jiang Yu‐Sheng , Li Guang‐Hua , Chen Jie‐Sheng
Published: February 2005

Two metal–organic coordination polymers [Ag(bipy)(UO2)(bdc)1.5] (bipy=2,2′‐bipyridyl, bdc=1,4‐benzenedicarboxylate) and [Ag2(phen)2UO2(btec)] (phen=1,10‐phenanthroline, btec=1,2,4,5‐benzenetetracarboxylate) were obtained by hydrothermal assembly of the d10 metal silver and the 5f metal uranium with mixed ligands. Both compounds form two‐dimensional networks with π–π overlap interactions between the aromatic fragments in the neighboring layers. In aqueous suspension the two water‐insoluble materials show photocatalytic degradation performance superior to that of commercial TiO2 (Degussa P‐25) when tested on nonbiodegradable rhodamine B (RhB) as model pollutant. The relationship between the structure of the photocatalysts and the photocatalytic activity was also elucidated. On the basis of the monitored intermediate species and the final mineralized products, it is proposed that the possible reaction mechanism for the photodegradation (oxidation) of RhB in aqueous solution catalyzed by the two assembly compounds involves photoexcitation of uranyl centers and molecular oxygen.
Environmental Effects on Vibrational Proton Dynamics in H5O2+: DFT Study on Crystalline H5O2+ClO4‐
Authors: Vener Mikhail V. , Sauer Joachim
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Crystal Structures of α‐ and β‐Mg2 [(UO2)3(SeO4)5] (H2O)16.
Authors: Krivovichev Sergey V. , Kahlenberg Volker
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Syntheses, Crystal Structures and Properties of the Tetrametaphosphimates M2II (PO2NH)4×8H2O with MII: Mg, Mn, Co and Zn.
Authors: Roemer S. Rebecca , Schnick Wolfgang
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
The Crystal Structures of the High‐Temperature Phases of Ag4Mn3O8.
Authors: Ahlert S. , Dinnebier R. , Jansen M.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Growth and Characterization of LiCaGaF6.
Authors: Sani E. , Rabe M. , Reck G. , Becker P. , Rossberg M. , Bertram R. , Klimm D.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Characterization of a Molecular Zinc Phosphate Ni(2,2′‐bipy)3× [ZnCl(H2PO4)3].
Authors: Lin Zhi‐En , Zhang Jie , Zheng Shou‐Tian , Yang Guo‐Yu
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
The Application of Chiral Amino Thiols as Catalysts in the Enantioselective Addition of Diethylzinc to Aldehydes.
Authors: Tseng Shi‐Liang , Yang Teng‐Kuei
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Oxadiazinones as Chiral Auxiliaries: Increased Diastereoselectivities in the Glycolate Aldol Reaction of Oxadiazinones.
Authors: Vaughn Jeremy F. , Hitchcock Shawn R.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthetic Stitching with Silicon: Geminal Alkylation—Hydroxylation of Alkynyl Carbonyl Compounds.
Authors: Trost Barry M. , Ball Zachary T.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Mesoporous Silica Anchored Ru Catalysts for Highly Enantioselective Hydrogenation of β‐Ketoesters.
Authors: Kesanli Banu , Lin Wenbin
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Microwave‐Induced Rapid Access to Aromatic and Heteroaromatic Sulfonamides under Solvent‐Free Conditions Without Using External Base.
Authors: Sharma Ashwani Kumar , Das Saibal Kumar
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Ruthenium‐Catalyzed Olefin Metathesis Double‐Bond Isomerization Sequence.
Authors: Schmidt Bernd
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Mechanistic and Stereochemical Aspects of the Asymmetric Cyclocarbonylation of 1,6‐Enynes with Rhodium Catalysts.
Authors: Schmid Thomas M. , Consiglio Giambattista
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Preparation of N‐(4‐Methylpentane‐2‐yl)‐N′‐ [2‐(2‐phenylpropane‐2‐yl)]‐benzene‐1,4‐diamine.
Authors: Sigmundova Ivica , Uhlar Jan , Toma Stefan
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Palladium‐Catalyzed Intramolecular O‐Arylation of Enolates: Application to Benzo[b]furan Synthesis.
Authors: Willis Michael C. , Taylor Dawn , Gillmore Adam T.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Selective Lithiation of 4‐(1H‐1‐Pyrrolyl)pyridine. Access to New Electron‐Releasing Ligands.
Authors: Martineau David , Gros Philippe , Fort Yves
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
One‐Pot Synthesis of Helical Aromatics: Stereoselectivity, Stability Against Racemization, and Assignment of Absolute Configuration Assisted by Experimental and Theoretical Circular Dichroism.
Authors: Watanabe Masashi , Suzuki Hiroshi , Tanaka Yasutaka , Ishida Toshimasa , Oshikawa Tatsuo , Tori‐i Akiyoshi
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Highly Efficient Synthesis of (R)‐ and (S)‐Piperazic Acids Using Proline‐Catalyzed Asymmetric α‐Hydrazination.
Authors: Henmi Yoshiaki , Makino Kazuishi , Yoshitomi Yayoi , Hara Osamu , Hamada Yasumasa
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Allylsilanes by Reductive Lithiation of Thioethers.
Authors: Streiff Stephane , Ribeiro Nigel , Desaubry Laurent
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Homogeneous Azidophenylselenylation of Glycals Using TMSN3—Ph2Se2—PhI(OAc)2.
Authors: Mironov Yuri V. , Sherman Andrei A. , Nifantiev Nikolay E.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis and Cytotoxicity of Derivatives of Di(3‐indolyl) Selenide.
Authors: Abele E. , Popelis J. , Shestakova I. , Domracheva I. , Arsenyan P. , Lukevics E.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Agariblazeispirol C (I) from the Cultured Mycelia of the Fungus, Agaricus blazei, and the Chemical Conversion of Blazeispirol A.
Authors: Hirotani Masao , Masuda Miyuki , Sukemori Aya , Hirotani Seiko , Sato Noriko , Yoshikawa Takafumi
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of 1,6‐Anhydro‐2,3,4‐trideoxy‐2,3‐epimino‐ and 1,6‐Anhydro‐2,3,4‐trideoxy‐3,4‐epimino‐β‐D‐hexopyranoses and Their NMR and Infrared Spectra.
Authors: Karban Jindrich , Budesinsky Milos , Kroutil Jiri
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Role of Platelet Derived Endothelial Cell Growth Factor/Thymidine Phosphorylase in Fluoropyrimidine Sensitivity and Potential Role of Deoxyribose‐1‐phosphate
Authors: de Bruin M. , van Capel T. , Smid K. , van der Born K. , Fukushima M. , Hoekman K. , Pinedo H. M. , Peters G. J.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Antibiotics from Australian Terrestrial Invertebrates. Part 1. Antibacterial Trinervitadienes from the Termite Nasutitermes triodiae.
Authors: Zhao Chunjiu , Rickards Rodney W. , Trowell Stephen C.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
8‐Substituted‐9‐deazaxanthines as Adenosine Receptor Ligands: Design, Synthesis and Structure‐Affinity Relationships at A2B.
Authors: Carotti Angelo , Stefanachi Angela , Ravina Enrique , Sotelo Eddy , Loza Maria Isabel , Cadavid Maria Isabel , Centeno Nuria B. , Nicolotti Orazio
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Heterocalixarenes
Authors: Sliwa W.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Utilization of 1,3‐Dicarbonyl Derivatives in Multicomponent Reactions
Authors: Simon Celine , Constantieux Thierry , Rodriguez Jean
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Reaction Systems
Authors: Behr Arno
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
The Thermal and Photostability of Solid Pharmaceuticals
Authors: Glass B. D. , Novak Cs. , Brown M. E.
Published: February 2005

For Abstract see ChemInform Abstract in Full Text.
Tubulin nucleation and assembly in mitotic cells: Evidence for nucleic acids in kinetochores and centrosomes
Authors: Pepper Daniel A. , Brinkley B. R.
Published: February 2005

A lysed cell system was used to study the organelle structure and nucleation of exogenous tubulin at kinetochores and centrosomes in mitotic PtK2 cells. We have used this lysed cell system in conjunction with nuclease digestion experiments to determine which specific nucleic acids (DNA or RNA) are involved in either the structure and/or microtubule‐initiating capacity of kinetochores and centrosomes. The results indicate that DNase I specifically decondenses the kinetochore plate structure, with the eventual loss in the ability of the chromosomes to nucleate microtubule assembly. DNase I had no effect on either the structure or nucleating capacity of centrosomes. Both RNase T1 and RNase A specifically attacked the amorphous pericentriolar material of the centrosomes, with a concomitant loss in the ability of this material to nucleate microtubule formation. Neither RNase appeared to affect the structure or nucleating capacity of the kinetochore. Therefore, the two types of nucleases appear to exert preferential effects on the different types of microtubule initiation sites in mitotic mammalian cells. The results suggest that DNA is a major component of the kinetochore, while RNA is a major component of the amorphous pericentriolar material. These findings support the concept that microtubule initiation sites in mitotic cells contain nucleic acids which are essential for the structural and functional integrity of the sites.
Redistribution of actin and fascin in sea urchin eggs after fertilization
Authors: Otto J. J. , Kane R. E. , Bryan J.
Published: February 2005

Following fertilization, the sea urchin egg cortex undergoes a structural change involving the assembly and organization of actin filaments into microvilli. Antifascin localizes this actin cross‐linking protein in the microvilli of the fertilized egg cortex but no organized staining is present in the unfertilized cortex. Determination of the actin content of eggs using the DNAase I inhibition assay indicates that actin is about 1.4% of the total protein. Approximately 90% of this actin is soluble in low calcium isotonic extracts of unfertilized eggs while only 60–65% can be recovered in identical extracts of fertilized eggs. Similar measurements for fascin using a radioimmunoassay indicate this molecule represents about 0.3% of the total egg protein, essentially all of which is recovered in low calcium isotonic extracts of unfertilized eggs. After fertilization only 65–70% of this actin cross‐linking protein is in the soluble phase. These results demonstrate a markedly different solubility for actin and fascin after fertilization, when the indirect immunofluorescence staining localizes fascin in the microvilli, and are consistent with the idea that fascin organizes newly polymerized actin filaments into the microvillar cores. A consideration of the amounts of actin and fascin incorporated into the cortex after fertilization and the number of microvilli on the egg surface indicates that the measured values are sufficient to account for the observed microvillar elongation.
Physarum myosin light chain binds calcium
Authors: Kessler D. , Eisenlohr L. C. , Lathwell M. J. , Huang J. , Taylor H. C. , Godfrey S. D. , Spady M. L.
Published: February 2005

Myosin from the slime mold Physarum polycephalum contains three sizes of polypeptides: a heavy chain and two light chains, LC‐1 and LC‐2. Using a simple qualitative test for calcium binding by comparing electrophoretic migration of the polypeptides in sodium dodecy1 sulfate (SDS) acrylamide gels in the presence and absence of calcium, we have found that Physarum myosin light chain LC‐2 migrates with an apparent molecular weight of 16,900 daltons in the presence of the metal ion chelator ethylene glycol bis (B‐aminoethyl ether) N,N′‐tetraacetic acid (EGTA). However, if calcium chloride is added to the sample prior to electrophoresis, the apparent molecular weight decreases to 16,100. Lanthanide and cadmium ions, but not magnesium, can substitute for calcium. Because the ionic radii of Ca2+, La3+, and Cd2+ are almost identical, we conclude that Physarum myosin LC‐2 possesses a very size‐specific binding site for calcium. Physarum myosin LC‐1 and the heavy chain give no evidence for binding calcium by this test. Since cytoplasmic streaming in the plasmodium of Physarum requires calcium, our evidence indicates that the calcium‐binding property of Physarum myosin LC‐2 may be important in regulating the production of force by actomyosin in the ectoplasm. Unexpectedly, the myosin light chain in Physarum capable of binding calcium, LC‐2, is the essential light chain, while LC‐1 is a member of the regulatory class of myosin light chains [V. T. Nachmias, personal communication]. Until now, essential myosin light chains have not been shown to have high affinity divalent cation binding sites. This means a new version of the myosin‐based model for actomyosin regulation by calcium may be required to explain cytoplasmic movement in Physarum, and perhaps in other motile systems involving cytoplasmic myosins as well.
Motion of polymorphonuclear leukocytes: Theory of receptor redistribution and the frictional force on a moving cell
Authors: Dembo Micah , Tuckerman Laurette , Goad Walter
Published: February 2005

As a cell moves over a surface, the distribution of membrane proteins that adhere to the surface will be changed relative to the distribution of these molecules on a static cell. Observations of this redistribution offer, in principle, evidence as to the mechanisms of membrane dynamics during cell locomotion. Toward extracting such information we present and analyze a mathematical model of receptor transport in the membrane by diffusion and convection, as affected by the making and breaking of the bonds between the receptors and the surface as the cell moves.

We show that the disruption of receptor‐surface bonds at the tail of the cell provides a mechanism by which the frictional force opposing a cell's motion is exerted, and calculate the magnitude of this force as a function of cell velocity. Assuming this to be the major contribution to the frictional force, we show that when the shear force on a cell is above a critical value it is no longer possible for the cell to slide across the surface. For such large forces, it is still possible for the cell to roll; alternatively the cell can be torn free of the surface.

Our analysis of existing data on movement of polymorphonuclear leukocytes indicates that cell motion is not accompanied by a bulk flow of membrane from the front to the back of the cell. The data also indicate that cells do not tend to roll as they move over a surface under normal conditions. The data are most consistent with a model where the membrane as a whole is stationary but where receptors that bind to the surface become coupled to sub‐membrane contractile proteins.
Video‐enhanced contrast, differential interference contrast (AVEC‐DIC) microscopy: A new method capable of analyzing microtubule‐related motility in the reticulopodial network of allogromia laticollaris
Authors: Allen Robert Day , Allen Nina Strömgren , Travis Jeffrey L.
Published: February 2005

A new method called Allen Video‐enhanced Contrast, Differential Interference Contrast (AVEC‐DIC) microscopy is shown to be sufficiently sensitive to detect several new features of microtubule‐related motility in the reticulopodial network of the foraminifer, Allogromia. The method takes advantage of the variable gain and offset features of a binary video camera to operate the DIC microscope under conditions highly favorable for video imaging, but in which the optical image is virtually invisible to the eye yet retains its full information when viewed by a suitable video camera. The improvements are made possible by setting a dé Senarmont compensator to λ/9‐λ/4 at maximal working aperture of internally corrected planapochromatic objectives. Under these conditions, the offset feature of the video camera can reject so much stray light from the instrument and specimen that contrast compares favorably with that observed in high‐extinction images, and polarizing rectifiers offer scarcely any advantage. Freed from the constraints of the light‐limited conditions of DIC microscopy, video images can be recorded 60 times per second, or over 1,000 times the rate of photomicrographs at comparable magnifications under high‐extinction conditions.

Application of this method to the reticulopodial network of Allogromia has shown that cytoplasmic organelles are translocated only in contact with single microtubules or bundles of microtubules, and that these organelles fail to move when separated from microtubules. Microtubules themselves undergo both axial translatory (“sliding”) and lateral “zipping and unzipping” movements that have been suggested to occur during mitosis and other biological processes.
The motion mechanics of Nitella filaments (Cytoplasmic streaming): Their imitation in detail by screw‐mechanical models
Authors: Foissner Iise , Jarosch Robert
Published: February 2005

Our knowledge about the actin‐containing characean filaments on the basis of light and electron microscopical investigations is reviewed. Dynamic filamentous networks, known already from isolated droplets, were detected in Nitella rhizoidal cells using light microscopical techniques. Earlier light microscopic observations in cytoplasmic droplets are confirmed and complemented by new model experiments with rotating helices. The motile phenomena occurring at the filament bundles (ring formation, wave propagation, particle translocation, net dynamics, rolling motions, formation of side arms) can, in this way, be imitated in detail. Thus, the concept of cytoplasmic streaming as a translocation along bundles of rapidly rotating helical filaments is supported. In order to explain unidirectional cytoplasmic streaming, a periodic winding up and unwinding of fine filaments is postulated by which ions are periodically bound and displaced. The formation of side arms which is favored during unwinding results in a screw‐mechanical different behavior of the filaments in the two directions of rotation and therefore causes permanent particle transport in one direction.
Tropomyosin binding to F‐actin protects the F‐actin from disassembly by brain actin‐depolymerizing factor (ADF)
Authors: Bernstein Barbara W. , Bamburg James R.
Published: February 2005

Brain or muscle F‐actin is rapidly depolymerized to monomeric actin in vitro by actin‐depolymerizing factor, a protein isolated from chick embryo brain. Binding of muscle tropomyosin to muscle F‐actin protects the F‐actin from depolymerization by this factor. A 8.4/1.0 molar ratio of actin subunits to tropomyosin, achieved by incubation of the F‐actin with excess tropomyosin, protects 58% of the F‐actin from depolymerization by excess actin‐depolymerizing factor for at least 3 hr at 25°C. Thus, actin‐depolymerizing factor seems to be specifically directed toward actin filaments lacking tropomyosin.
Pseudopod formation and membrane production during prey capture by a heliozoon (feeding by Actinophrys, II)
Authors: Hausmann Klaus , Patterson David J.
Published: February 2005

Two phases of prey capture by the heliozoon Actinophrys sol are documented by electron microscopy. The phases are those of prey adhesion to the predator and enclosure of the prey by the predator. Adherence is brought about by numerous small pieces of adhesive membrane produced by the predator at the site of prey contact. Some of the heliozoan extrusomes expel their contents at this time, but the significance of this event is unclear. Enclosure of the prey is effected by a funnelshaped pseudopodium. This is drawn over the prey by the action of the leading margin. The ultrastructural appearance of the cytoplasm of the leading margin differs from the rest of the cell, being homogeneous and finely filamentous. Both force and traction for the progression of the pseudopod are generated primarily at the tip. During the development of the funnel‐pseudopod, extrusomes expand and fuse with each other and with the plasma membrane. Their investing membrane is thereby made available as food vacuole membrane.
Epithelial cell motility: The effect of 2‐deoxyglucose on cell migration, atp production, and the structure of the cytoplasmic ground substance in lamellipodia of epithelial cells in culture
Authors: Gibbins J. R.
Published: February 2005

Using a line of epithelial cells (SCCA5) derived from a spontaneous rat carcinoma, the glucose analogue 2‐deoxyglucose (2DG) has been shown by time‐lapse cinemicrography to produce a cessation of motility by 1 hour that can be reversed by replacement of the 2DG, and does not occur in equivalent media with or without glucose or in 2DG‐containing media with added pyruvate and citrate. The effect on the cells at the edge of an epithelial island is to prevent the formation of new lamellipodia and produce a progressive retraction and condensation of lamellipodia already present. This effect of 2DG on motility corresponds with a significant reduction in the level of ATP that is partially restored after 30 minutes in the recovery incubation. Only a slight reduction in protein synthesis occurs in the presence of 2DG. The external morphology and the cytoplasmic ground substance of the cells were studied by scanning electron microscopy and high voltage electron microscopy respectively. It was found that after incubation in 2DG for 1 hour the outline of the free edges of the cells was distorted resulting in redistribution of microvilli, condensation of cytoplasm into strands, and irregular projections from the edges of residual lamellipodia. The structure of the cytoplasmic ground substance in lamellipodia from cells incubated in 2DG for 3 hours was distinctly different from that in cells incubated for 3 hours in 2DG then recovered for 25 minutes, or in cells incubated in glucose‐containing medium for 3 hours. In the 2DG‐treated cells the lattice‐like structure evident in critical‐point‐dried cells was condensed into short thick strands that terminated in bulbous ends, whereas in cells recovered for 25 minutes the lattice material was elongated and tapering and the interlattice space relatively expanded. The results obtained support the concept of modulation occuring in the structure of the microtrabecular lattice component of the cytoplasmic ground substance coincident with alterations in cell function and metabolic state.
Tomato actin and myosin: Contractile proteins from a higher land plant
Authors: Vahey Maryanne , Titus Margaret , Trautwein Richard , Scordilis Stylianos
Published: February 2005

This paper describes the initial isolation of actin‐ and myosin‐like proteins from the cytoplasm of the endocarp tissue cells of the fruit of the tomato, Lycopersicon esculentum. Low ionic strength buffers extracted the 42,000 molecular weight tomato actin in the depolymerized form. Tomato actin can be polymerized in 0.1 M KCl, 2 mM MgCl2 to form 6 nm diameter filaments resembling rabbit skeletal muscle F‐actin in their ultrastructure and pattern of decoration with rabbit myosin subfragment‐1 (S‐1). Tomato F‐actin activates the low ionic strength Mg2+ ATPase of rabbit S‐1 up to ten‐fold. High ionic strength extracts of tomato yield a myosinlike enzyme whose ATPase activity in 0.5 M KCl is maximal in the presence of K+‐EDTA and is repressed in the presence of Mg2+. The column‐purified enzyme forms a complex with rabbit F‐actin, which can be dissociated by Mg2+ ATP. The low ionic strength Mg2+ ATPase of tomato myosin can be activated ten‐fold by rabbit actin and up to nineteen‐fold by tomato actin. No activation of the tomato myosin by rabbit F‐actin occurs in the absence of free calcium ions.
Dynamic aspects of the supramolecular organization of intermediate filament networks in cultured epidermal cells
Authors: Jones Jonathan C. R. , Goldman Anne E. , Steinert Peter M. , Yuspa Stuart , Goldman Robert D.
Published: February 2005

We have shown, by indirect immunofluorescence microscopy using an antiserum against the mouse keratin subunit K2 and by electron microscopy, that transformed (PAM) and primary (PME) mouse epidermal cells possess extensive net works of IF bundles. Following trypsinization and replating of PAM cells, IF bundles are seen to move as a continuous net work from a perinuclear zone into the peripheral cytoplasmic regions. In PAM cells lysed in high‐ionic‐strength solutions containing Triton ×‐100 and DNAase‐1, IF bundles appear to be closely associated with nuclear envelope remnants and, in some cases, appear to be attached to nuclear pore complexes. PME cells cultivated in low Ca2+‐containing medium possess perinuclear birefringent arrays of IF bundles. Within 2 hours of switching the cells to normal Ca2+ levels, the PME IF bundle network moves towards and establishes contact with the cell surface as desmosomes form. Live cells observed by phase contrast and fixed cells observed by immunofluorescence microscopy demonstrate that desmosomes can be distinguished as dark bands separating neighboring cells. There is little difference between the major proteins seen in SDS‐polyacrylamide gel profiles of isolated IF bundle net works from PME cells before and after the Ca2+ switch. Therefore, a reorganization of relatively insoluble membrane‐associated protein following the Ca2+ switch may be involved in desmosome formation. The isolated IF networks from PAM cells differ in protein composition compared to the PME IF networks. This may be related to the greatly reduced number of desmosomes in PAM cells. The IF bundle system in epidermal cells appears to be involved in shape formation, shape maintenance, the establishment of desmosomes, nuclear centration, and cell‐cell contact.
In vitro nucleation of microtubules from microtubule‐organizing center prepared from cellular slime mold
Authors: Kuriyama Ryoko , Sato Chikako , Fukui Yoshio , Nishibayashi Soryu
Published: February 2005

Nucleus associated bodies (NABs) were isolated from Dictyostelium discoideum or Dictyostelium mucoroides and their ability to nucleate microtubules in vitro was examined.

NABs were localized at the tapered ends of the nuclei and released from lysed cells in complex with the nuclei. Microtubules radiating from the NAB could also be isolated with the complex under microtubule stabilizing conditions. The ultrastructure of the isolated NAB showed it to be composed of a core structure surrounded by an amorphous matrix.

The ability of isolated NABs to nucleate microtubules in vitro was demonstrated by incubation with exogenous brain microtubule protein. Microtubule assembly was easily visualized by dark‐field or immunofluorescence microscopy. Polymerization of microtubules seemed to be initiated not from the core structure but from the surrounding matrix.

The number of microtubules polymerized from the NAB was directly counted in whole‐mount preparations by electron microscopy, which provided a quantitative assay for the NAB activity. The nucleating activity of NAB was quite unstable and its half‐life was calculated as about 5 hours. The activity was sensitive to protease digestion and was also temperature sensitive but could be stabilized by addition of glycerol or storage at – 80°C or in liquid nitrogen. These characteristics are analogous to those of the centrosomes in cultured mammalian cells and a possible explanation of their similarity is discussed.
Isolation of a new actin‐binding protein from dictyostelium discoideum
Authors: Condeelis John , Geosits Stephen , Vahey Maryanne
Published: February 2005

A new actin binding protein has been purified to homogeneity from amoebae of Dictyostelium discoideum. This protein is a single polypeptide with a molecular weight of 120,000 upon sodium dodecyl sulfate gel electrophoresis. It is soluble and trypsin‐sensitive, contains no carbohydrate, increases the viscosity and sedimentation rate of F actin, and inhibits the actin‐stimulated Mg ATPase of rabbit muscle heavy meromyosin. The interaction of 120,000‐dalton protein with F actin is not inhibited by millimolar ATP, pyrophosphate, or micromolar calcium. The 120,000‐dalton actin binding protein increases the initial rate of actin polymerization and decreases the critical concentration of actin at steady state.

These properties demonstrate that 120,000‐dalton protein from Dictyostelium discoidum is not a myosinlike protein. Rather, this protein is probably involved in regulating the assembly of the actin cytoskeletion.
Binding stoichiometry of 21S dynein to A and B subfiber microtubules
Authors: Warner F. D. , McIlvain Jane H.
Published: February 2005

The binding properties of Tetrahymena 21S dynein to doublet A and B subfiber microtubules were analyzed by both a turbidimetric assay (Δ A350 nm) and electron microscopy. KCl‐extracted, sucrose‐gradient, purified 21S dynein binds to each of the two kinds of axonemal microtubules in both ATP‐insensitive and ATP‐sensitive modes, even though only a single type of binding occurs to each of the subfibers in situ. Total dynein bound to axonemal microtubules is a composite of binding that is sensitive to dissociation by ATP and binding that is insensitive to ATP. Each exhibits a different binding profile. Total binding exhibits a sigmoid profile (h = 1.93) and saturates at 1.49 mg D/mg T. ATP‐sensitive binding likewise exhibits a sigmoid profile (h = 2.66) but saturates at 1.06 mg D/mg T. Binding occurs with a similar affinity for both A and B subfibers. The Hill coefficient (h) for ATP‐sensitive binding implies positive cooperativity between binding events. ATP‐insensitive binding was studied independently in 20 μM ATP, 10 μM vanadate, which blocks ATP‐sensitive binding. ATP‐insensitive binding exhibits a hyperbolic profile (h = 1.0) and likewise occurs along each of the two kinds of axonemal tubules. Binding saturates at 0.87 mg D/mg T. The binding data suggest that the tubulin dimer has conserved both ATP‐sensitive and ATP‐insensitive binding sites for 21S dynein, even though the sites may not be expressed in vivo.
Dictyostelium calmodulin: Production of a specific antiserum and localization in amoebae
Authors: Bazari Wendy L. , Clarke Margaret
Published: February 2005

A rabbit antiserum was raised against calmodulin from the eukaryotic microorganism Dictyostelium discoideum. In double immunodiffusion experiments, the antiserum formed an immunoprecipitation line with Dictyostelium calmodulin but not bovine brain calmodulin; competition radioimmunoassays showed no cross reactivity between the antiserum and calmodulins from bovine brain and spinach. The calmodulin content of vegetative Dictyostelium amoebae, determined by competition radioimmunoassay, was 0.5 μg/mg protein; similar levels were found in developing cells. The antiserum was used to visualize the distribution of calmodulin in Dictyostelium amoebae by indirect immunofluorescence. Cells were examined under various conditions: in suspension, attached to a substrate, and while phagocytosing yeast cells. In all cases, anticalmodulin staining was concentrated in the cell cortex. Parallel experiments using a monoclonal antibody against Dictyostelium myosin showed that this protein is also enriched in the cortical region of the cell.
Purification and polypeptide composition of dynein ATPases from chlamydomonas flagella
Authors: Pfister K. Kevin , Fay Rose B. , Witman George B.
Published: February 2005

Extraction of isolated, demembranated flagellar axonemes of Chlamydomonas reinhardii with 0.6 M KCl solubilized 77–92% of the total axonemal Mg++ or Ca++‐ATPase activity, which sedimented as 18S and 12S peaks in sucrose density gradients. The ATPases of these two peaks were further purified by hydroxyapatite (HAP) column chromatography. The ATPase activity of the 18S peak eluted from the HAP column as a single peak coinciding with the protein peak. The HAP purified 18S ATPase had a specific activity of ∼2.0 ± 0.5 μmoles Pi hydrolyzed min/mg and was associated with four high molecular weight (HMW) polypeptides of ∼ 310,000‐340,000 daltons, two intermediate molecular weight (IMW) polypeptides of 78,000 and 69,000 daltons, and eight low molecular weight (LMW) polypeptides of 7,800–19,600 daltons. When the 12S sucrose gradient peak together with a trailing shoulder were chromatographed on HAP, the ATPase activity was eluted in two peaks designated 12S and 10.5S on the basis of the sedimentation properties of their associated polypeptides. The 12S peak contained a single dynein ATPase having a specific activity of ∼ 0.6 ± 0.3 μmoles Pi hydrolyzed min/mg and associated with ∼ 330,000‐, 21,700‐, and 18, 100‐dalton polypeptides. The 10.5S peak contained several high, intermediate, and low molecular weight polypeptides; of these, on HMW polypeptide and one 28,700‐dalton polypeptide correlated well with the ATPase activity. The purified ATPases had no polypeptides in common; each therefore represents a discrete dynein. Based on protein recovered in the purified fractions, 18S dynein represents ∼ 9.2% of the total axonemal protein; 12S dynein represents ∼ 4.7% of the axonemal protein.