Six-pointed Star Research Articles

Structure and Lipophilicity Profile of 2,3-Anhydro-α-cyclomannin and Its Ethanol Inclusion Complex

Readily available from alpha-cyclodextrin in three steps, 2,3-anhydro-alpha-cyclomannin composed of six alpha-(1-->4)-linked 2,3-anhydro-D-mannopyranose residues, crystallizes well when precipitated from aqueous ethanol. An X-ray structure reveals the macrocycle to contain ethanol in its cavity, thus representing the first inclusion complex of a non-glucose cyclooligosaccharide. The wider rim of the torus-shaped macrocycle holds the six epoxide rings whose oxygens point away from the cavity, thereby sculpturing the unique over-all shape of a six-pointed star.

Theos Epiphanes: Crisis and Response

Burton Y. Berry gave a unique silver tetradrachm to the American Numismatic Society in 1959. The obverse of the coin bears the diademed and draped bust of a Ptolemaic king wearing sideburns, and, in the left field behind the king's portrait, a six-pointed star or comet (*). The reverse bears an eagle facing left on a thunderbolt, an inscription ΠΤΟΛΕΜΑΙΟϒ ΒΑΣΙΛΕΩΣ (“of Ptolemy the king”), a six-pointed star or comet in the right field, and a monogram (ΠΑ) in the left field in front of the eagle. Dawson Kiang first published the tetradrachm in 1962. Dating it to the reign of Ptolemy VI Philometor (180–145 BCE), Kiang supposed that the portrait was an effigy of that monarch. In this article, I shall identify the portrait with Ptolemy V Epiphanes and submit a new hypothesis about the origin of his surname in 199/8 BCE.

Diffuse X-ray scattering in potassium lithium sulfate, KLiSO4

Detailed diffuse X-ray scattering patterns of potassium lithium sulfate, KLiSO4, in sections normal to [00.1], have been recorded using a position-sensitive detector system. A number of distinctive diffuse features are observed including elongated diffuse peaks near Bragg-peak positions, bands of weaker intensity running normal to a*, b* etc. and darker regions relatively free from scattering in the shape of hexagons and a six-pointed star. Monte Carlo simulation of simple potential models has been carried out in an attempt to explain this scattering and also the observation from Bragg analysis [Schulz, Zucker & Frech (1985). Acta Cryst. B41, 21–26] that mean-square atomic displacements for the apical O(1) atom show a pronounced threefold symmetry. A simple potential, in which harmonic (Hookes law) springs with lengths equal to the observed average bond distances are assumed between the different types of nearest-neighbour atom pairs, is able to account qualitatively for all of the observed diffraction features but gives quite isotropic atomic displacement distributions. A second model is described, which assumes that a small number of point defects are present, in which the potassium sites are occasionally occupied by lithium. The distortion of the very flexible LiO4 framework around such defects can account for the trigonal shape of the O(1) sites while still giving diffuse diffraction patterns similar to those from the simpler harmonic model.

Cytoskeletal dynamics ofApedinella radians (Pedinellophyceae) II. Cell division and maintenance of cell polarity and symmetry

The dynamics of the cytoskeletal proteins centrin, actin, and tubulin were followed during cell division in the unicellular phytoflagellateApedinella radians (Pedinellophyceae). Three centrin, or centrin-like, components appear to coordinate independent developmental events during cell division. The first component, basal body centrin, maintains a physical link between basal bodies and the anterior nuclear membrane. Basal body centrin divides in two at metaphase, and each portion segregates with two basal bodies at anaphase. As the positioning of basal bodies defines the anterior region of the cell, basal body centrin appears to play a role in maintaining cell polarity throughout the cell cycle. The second centrin component consists of an array of filamentous bundles arranged as a six-pointed star. During cell division, the star undergoes a conformational change resulting in two distinct centrin triangles, one distributed to each daughter cell, suggesting that centrin filamentous bundles are involved in maintaining cell (radial) symmetry. The third centrin component is transient and associates with the spindle poles, emerging prior to mitosis and remaining until late anaphase/early telophase. Spindle pole centrin establishes temporary horizontal bipolarity, thereby establishing the spindle axis. Unlike centrin filamentous bundles, actin filamentous bundles depolymerize prior to mitosis, indicating they do not influence cell symmetry during cell division. Mitosis is described for the first time in a pedinellid and features a closed spindle, the absence of rhizoplasts and a persistent spindle.

Cytoskeletal dynamics ofApedinella radians (Pedinellophyceae) III. Post-division development, maintenance of cell symmetry, and the re-establishment of interphase morphology

The dynamics of the cytoskeletal proteins centrin, actin, and tubulin were investigated during post-division development in the radially symmetrical phytoflagellateApedinella radians (Pedinellophyceae). Each daughter cell inherits a triangular arrangement of centrin filamentous bundles that develops, during post-division, into the six-pointed star configuration observed at interphase. This coincides with developmental processes including plaque duplication and migration, chloroplast division and migration, and spine-scale deployment. Centrin filamentous bundles appear to be involved in maintaining radial symmetry throughout the cell cycle and re-establishing interphase morphology. Actin filamentous bundles, prominent at interphase, depolymerize just prior to mitosis and do not reform until late post-division, indicating they are not involved in maintaining cell symmetry during cell division. Although the precise dynamics of microtubular triads and their associated cylindrical caps has not been determined, they may work in concert with centrin filamentous bundles in re-establishing interphase morphology. Three centrin, or centrin-like, components inA. radians appear to coordinate independent architectural events during the cell cycle. The nature of the three centrin components is discussed and compared to the flagellar roots/pericentriolar material of the eukaryotic centrosome.

A "Neo-Babylonian" Seal from Tell Taanach

A seal found on the surface of Tell Taanach 40 years ago may provide additional evidence for occupation of the site in the late Assyrian/Neo-Babylonian period.

The Cult of Mithras in Ancient Colchis

The cult of Mithras in Colchis was widespread from the Hellenistic period onward. This has been borne out by a fragment of a Colchian amphora discovered during excavations at the city-site of Pichvnari, bearing the circular imprint of a seal described in detail here (it depicts a horseman, a six-pointed star, a bird and a sprig). This cult made its way to Colchis from the neighbouring state of the Achaemenids. Its syncretic character enabled it gradually to blend into the cult of the sun, Helios being a widely venerated deity in Colchis. Mithras must have been the precursor of Saint George in pagan Georgia.

Effects of Attainable and Unattainable Goals on Mirror-Tracing Performance and Retention of a Motor Task

Attainable and unattainable goals' effect on mirror tracing a six-pointed star was investigated. Three groups of male college students were randomly assigned to groups: control, attainable goals, or unattainable goals. Subjects were evaluated for time and error in 28 trials. Goals were individualized on the basis of each subject's performance on the previous three trials. Knowledge of results and goals were given for both time and error on the first 18 trials but not the last 10. The use of goals led to superior performance and short-term retention, but no significant differences were found between subjects given attainable and unattainable goals. Significant correlations of time and error in some experimental blocks suggest that, under increasingly difficult conditions, quality (avoidance of error) may be sacrificed for quantity (time).

Serial propagation of porcine enteric calicivirus-like virus in primary porcine kidney cell cultures.

A porcine enteric calicivirus-like virus was adapted to serial propagation in primary porcine kidney cell cultures. Attempts to propagate this virus in primary porcine kidney cells in the presence of trypsin or pancreatin or without medium supplementation were unsuccessful. A low-pH medium (pH 6.8) was also ineffective in virus propagation. Successful serial propagation of the virus required the presence of an intestinal-content preparation, derived from uninfected gnotobiotic pigs, in the cell culture medium. The best results were obtained with six-well plate cultures which were centrifuged after virus inoculation. Infected cells were detected by immunofluorescent staining of cell monolayers or detached cells which were harvested by centrifugation. Infected cells were first detected at passage 4 (1% infected cells), and infectivity increased with successive passages, with as many as 80% of the cells infected by passage 16. Extensive cytopathic effects were observed in inoculated cell cultures, but not in uninoculated control cell cultures, at each passage level after passage 13. The infected cells became separated, rounded, and detached, forming holes in the cell monolayer. Only virus particles exhibiting the six-pointed star appearance or stain-filled, cup-shaped depressions characteristic of caliciviruses were detected in inoculated cell culture supernatants by immune electron microscopy. Attempts to determine the titer of the virus by a cell culture immunofluorescence assay or plaque assay were unsuccessful.

The Effects of Memory and Abstractive Integration on Children's Probability Learning

ive integration task.-Abstractive integration was assessed by a task2 adapted partly from the Frostig Developmental Test of Visual Perception (Frostig, 1966). The task had three parts, each designed to assess an ability considered crucial in probability learning: Part A, the ability to separate or abstract one particular feature out of several different ones; Part B, the ability to focus on a particular feature and identify it despite differences in its occurrence and distracting stimuli; and Part C, the ability to identify which of a series of highly similar stimuli deviates in some minor but specified sense. Part A consisted of eight items, each depicting two or more geometrical figures superimposed on or circumscribing each other. For example, there was a square and a partially superimposed triangle, a five-pointed star intersecting with two four-pointed and two six-pointed stars, and a circle cluttered by various intersecting curves and oval shapes. The items were drawn in black ink on a white background and presented on separate pages in a small booklet (17 x 13 cm). The items were arranged by increasing level of difficulty (determined by pretest findings for number of errors, time to completion, and children's remarks). There were also eight display cards (17 x 13 cm) depicting the key figures that the child was to locate (a square, triangle, cross, crescent, six-pointed star, five-pointed star, oval, and diamond). Part B (designed to assess the ability to identify a particular form despite transformations in its size and position) included four drawings presented in random order on separate pages. Embedded in the drawings was a total of eight circles and 13 squares. These forms differed in size, location, and salience. There were also many distracting forms that resembled circles and squares, e.g., oblongs, ovals, semicircles, parallelograms, etc. Pretesting showed that children found the task to be interesting and challenging both because the key figures were cleverly hidden and because it was necessary to decide in so many problematic cases whether the form was indeed a circle or a square or merely a distracting stimulus. Part C (designed to assess the ability to identify a deviant feature) consisted of rows of five items that resembled one another. There were 10 different rows presented in random order on separate pages in a small booklet. The drawings depicted familiar

Comparison of the Features of Astroviruses and Caliciviruses Seen in Samples of Feces by Electron Microscopy

Astroviruses and caliciviruses may both be observed in the feces of babies by electron microscopy and are two of the viruses whose relationship to infantile diarrhea is still being established. Although similar in size and in their star-shaped surface configurations, they differ in detailed structure. The astrovirus has a round unbroken edge, a six-pointed star with a white center, and surface hollows that are triangular. The calicivirus has a feathery edge, a six-pointed star with a dark hollow in the center (Star-of-David) appearance), and surface hollows that appear round or oval. Because only a minority of the virions of both viruses exhibit a completely characteristic structure, careful searching may be necessary to distinguish between the two viruses.

Detection and transmission of 30 nm virus particles (astroviruses) in faeces of lambs with diarrhoea

An outbreak of diarrhoea in lambs was investigated, and electron microscopic examination revealed small round virus-like particles in the faeces from eight of seventeen lambs. A bacteria-free filtrate of faeces from one lamb was given orally to a gnotobiotic lamb, which subsequently excreted virus in faeces. Intestinal contents were collected from this lamb and a filtrate given orally to two further gnotobiotic lambs, which subsequently developed diarrhoea and excreted virus in faeces. The mean diameter of the virus particles was 29.7 nm, and 12 per cent of them showed their surface structure arranged in the form of a six-pointed or five-pointed star. They were similar to those particles previously observed in human infant faeces which were referred to as "astroviruses". The passage through gnotobiotic lambs with development of diarrhoea showed that these particles were animal viruses which were probably pathogenic for lambs.

Ultrastructure of Bacillus licheniformis bacteriophage BLE and its DNA

A new bacteriophage has been isolated and its form has been described. As far as we know, it is active on Bacillus licheniformis only and is called BLE. The phage particles were negatively stained with phosphotungstic acid. The head of phage BLE is bacilliform and is about 50 nm wide and 130 nm in length. The noncontractile tail is 240 nm in length and 6.3 nm thick and has a cross-striated sheath. The base plate of the tail exhibits the shape of a six-pointed star. From the phage BLE, phenol-extracted DNA molecules were prepared for electron microscopy by the cytochrome c film technique of A. Kleinschmidt and R. K. Zahn ( Z. Naturforsch. B, 14, 770–779). Some DNA molecules probably of circular form were observed. Measurement of contour lengths of DNA molecules gave a value 21 ± 0.8 gm, which corresponds to a molecular weight of (41.1 ± 1.5) × 103.

Disruption of Vi bacteriophage III and localization of its deacetylase activity.

It has been shown that particles of Vi bacteriophage III catalyse deacetylation of O-acetyl pectic (polygalacturonic) acid, a structural analogue of Vi polysaccharide (Vi antigen). Using this substrate, and determining the acetic acid liberated by gas-liquid chromatogrphy, a method for the estimation of Vi phage deacetylase activity has been developed. Purified particles of Vi phage III were exposed to a variety of mildly dissociative reagents and conditions, and then tested for plaque-forming and for deacetylase activity. They have also been inspected under the electron microscope. Osmotic shock, and incubation in the presence of ethylenediamine tetraacetic acid (greater than or equil 0-01 M), or of L-arginine (0-25 M), were found to cause disintegration of the virions into empty head capsids, deoxyribonucleic acid, and base plates still carrying the spikes. The mixtures of viral fragments exhibited an increased deacetylase activity. Using zonal sedimentation and ion exchange chromatography, the phage fragments obtained by treatment with ethylenediaminetetraacetic acid have been fractionated and the base plates isolated. Amongst the viral components, these structures showed the highest specific deacetylase activity. They had the shape of six-pointed stars (about 9-5 nm inner, and 14-5 nm outer diam.) with a central hole or plug (approximately 3 nm), carrying six spikes, roughly cylindrical organelles of approx. 11 X 4 nm, one at each of the points. Of the polypeptides of six sizes (P.1, about 153,000 daltons; P.2, 91,000; P.3, 71,000; P.4 56,500; P.6, 22,000), detected in whole Vi phage III virions by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, only two, P.2 and P.3 were found in the base plates.

Ultrastructure of tubulin paracrystals from sea urchin eggs, with determination of spacings by electron and optical diffraction

The structure of isolated paracrystals of tubulin, induced in unfertilized sea urchin eggs with vinblastine sulphate, has been studied in sectioned material. Three distinctive patterns have been found and all can be observed by the systematic reorientation of sections in a goniometer stage or by sectioning different, suitably orientated paracrystals. One pattern is made up of six-pointed stars: the other two consist of arrays of parallel lines; one with repeating rungs approximately perpendicular to the main axis; the other of linear arrays of interconnected beads. The principal dimensions of these patterns have been determined by diffraction methods.

Escherichia coli capsule bacteriophages. III. Fragments of bacteriophage 29.

A glycanase activity, catalyzing the depolymerization of host capsular polysaccharide, is associated with Escherichia coli capsule bacteriophage no. 29, a small virus with an isometric head, carrying a base plate with a set of spikes. The bacteriophage particles were disrupted by mild acid treatment (5 to 8 min at pH 3.5 and 37 C), and the enzymatically active fragments were isolated and subjected to sodium dodecyl sulfate-gel electrophoresis as well as to electron microscopy. Of the at least nine different polypeptide chains found in the complete virion, three (of 57,000 plus or minus 3,000, 29,500 plus or minus 2,000 and 13,500 plus or minus 1,000 daltons) were detected in detached base plates. They had the appearance of six-pointed stars of about 14 nm in outer diameter, with a central hole or prop, carrying six (or, possibly, a multiple thereof) spikes. Two sizes of polypeptide chains (57,000 and 29,500) were found in pure spikes, cylindrical particles of about 14.5 to 15 nm in length and 5 nm in diameter, and one (57,000) in -- still capsule depolymerizing -- spike subunits of roughly 5 nm in diameter. Phage 29 spike preparations, homogeneous in analytical ultracentrifugation and immunoelectrophoresis, were found to have a molecular weight of 245,000, as determined from the sedimentation equilibrium, and to contain equimolar amounts of the two polypeptides, probably three copies of each per organelle. The amino acid analysis of the isolated spikes revealed that aspartic acid, alanine, serine, and glycine are their dominant constituents; no amino sugars or other carbohydrates were detected in the preparations.

A bacteriophage-induced depolymerase active on Klebsiella K11 capsular polysaccharide

A capsule depolymerase induced by bacteriophage No. 11 on Klebsiella 390 (03: K11), has been isolated. The material was essentially homogeneous in analytical ultracentrifugation and immunoelectrophoresis. It catalyzes the hydrolysis mainly of β- d-glucopyranosido-(1 → 3)- d-glucuronic acid, but also that of a few (1 in about 20) d-galactopyranosido-(1 → 3)- d-glucose bonds in K11 capsular polysaccharide. The depolymerase consists of dimers of club- or drop-shaped particles of a molecular weight of 155,000 ± 10,000 containing one polypeptide chain of about 62,500 and one of 94,000 dalton. Klebsiella bacteriophage No. 11 is an isometric virus; its head has a diameter of about 450 Å. It bears a base plate of about 265 Å diameter which has the shape of a six-pointed star with a central hole or prop, carrying two spikes for each of its six points. The following observations support the view that the depolymerase consists of pairs of free spikes of phage 11: (I) The depolymerase monomers and phage spikes in situ have the same dimensions. (II) Polypeptide chains of the same size as the two in the depolymerase also occur in whole virus. (III) The free depolymerase shows approximately the same enzymatic activity as do phage spikes in situ. Purified depolymerase and bacteriophage particles catalyze the hydrolysis of the same bonds in Klebsiella K11 capsular polysaccharide, ultimately forming oligosaccharide fragments of one, two, and three repeating units of the (alkali-treated) polymer. (IV) Phage 11 and the depolymerase strongly cross-react serologically, and anti-depolymerase IgG antibodies specifically adhere to the spike region of whole virus.

Formation of the Prolamellar Body in 8-Day, Dark-Grown Seedlings

The development of the prolamellar body in etioplasts of dark-grown seedlings of Phaseolus vulgaris is followed through the 8th day. From 2 to 6 days there is an increase in plastid size and starch content and synthesis of a system of porous lamellae which appear to arise, as such, from the inner component of the plastid envelope. From 6 to 8 days much of the starch disappears accompanied by rapid membrane synthesis resulting in an extensive prolamellar body. A model of the prolamellar body is discussed in which the basic structural unit is a six-pointed star with four tubules joining at each node. Observation of face views of the porous peripheral lamellae at their juncture with the prolamellar body suggests the origin of the prolamellar body by the continued contraction of the porous lamellae and the formation of interconnecting tubules between adjacent lamellae. The pores of the peripheral lamellae appear to correspond to the areas of stroma within each star module. Short lengths of membranes of individual peripheral lamellae fuse, forming short overlaps which resemble small, two-compartmented grana. It is postulated that this is the initial step in grana formation.

Ultrastructure of a cytoplasmic polyhedrosis virus affecting the monarch butterfly, Danaus plexippus: I. Development of virus and normal polyhedra in the larva

An account is given of the replication cycle of the virus and the development of normal polyhedra, as contrasted with a cubic mutation, in a cytoplasmic polyhedrosis affecting the larvae of Danaus plexippus, the monarch butterfly. The polyhedra are somewhat unusual being almost spherical and varying in size from very small to 5 μ in diameter. Two general lattice patterns were observed in the polyhedra, a dot pattern and a line pattern which are two views of the same crystal lattice. In the early stages of the disease a virogenic stroma forms in the cytoplasm in which the virus particles appear to develop. At a later stage what has been termed a crystallogenic matrix is produced which surrounds the developing polyhedra. Both contain virus particles but no normal cellular components. The crystallogenic matrix has many complete virus particles in it while the virogenic stroma has few complete, but many incomplete, particles present. The virus particle itself consists of a central electron-opaque core surrounded by a less dense capsid. The particle measures about 670 A in diameter, and the core, which may be hexagonal or pentagonal, measures about 350 A. There are 12 projections on the surface of the capsid measuring about 170 A in length, in section often six projections are visible forming a six-pointed star. An unusual feature is the presence of a “tail” extending from a vertex of the hexagon; the length of the tail is almost that of the diameter of the virus particle and is much longer than the regular projections. There is circumstantial evidence that the virus is transovarially transmitted.

The infection of Escherichia coli by T2 and T4 bacteriophages as seen in the electron microscope II. Structure and function of the baseplate

The baseplate of the T-even bacteriophage seems to play a central role in the infection of the host. In the native particle it is attached both to the extended sheath and to the tip of the central hollow needle. It has the shape of a flat hexagon with a short pin at each corner and a trigonal plug in its center. In addition, six long tail fibers are attached to its vertices. These fibers are responsible for the initial attachment of the particle to the susceptible host cell. Subsequently, the short pins become attached to the cell surface. A series of structural changes in the baseplate and the sheath follow. The baseplate becomes a six-pointed star with the tips pointing diagonally away from the bacterial surface and with the six long tail fibers attached to them. The baseplate's attachment to the needle is dissolved and an 80 A hole is found instead of the baseplate's central plug. These transformations in the baseplate may initiate the contraction of the sheath. Since the sheath is connected to the needle near the neck of the particle, its contraction thus causes the needle to slide through the baseplate and press against the bacterial wall. This forces the baseplate away from the cell wall and creates tension in the pins which are drawn out into short tail fibers. It seems that the needle is thus forced to penetrate the cell wall (which may be weakened by phage enzymes) and to serve as a channel through which the phage's DNA may pass into the cell.