Yellow Spread Research Articles

Cell‐specific heterogeneity of Cx43‐positive gap junctions in the mammalian kidney

ObjectiveConnexin 43 (Cx43) is a gap junction‐forming protein which mediates the intercellular passage of molecules < 1000 Da. In the kidney, Cx43 was reported in glomerular vessels and mesangium. Own results prompted us to reevaluate the distribution of Cx43 and its phosphorylated form, phospho‐S368‐Cx43 (pCx43), within the different zones of the rat kidney and in cultured fibroblasts in more detail.MethodsCx43 and pCx43 were localized by immunofluorescence in rat kidney sections and cultured human fibroblasts. High‐resolution immunostaining of Cx43 was achieved by ultrastructural immunogold labelling on electron microscopy sections. Double‐labelings with anti‐aquaporin 1 (AQP1), aquaporin 2 (AQP2), zonula occludens‐1 (ZO‐1), and cyclooxygenase‐2 (COX‐2) were conducted to clarify Cx43 distribution in the rat renal medulla. Cultured human fibroblasts served to study intercellular transfer of fluorescent lucifer yellow.ResultsCx43 was distributed in renal arterial and arteriolar endothelia, lymphatic vessel walls, peritubular capillaries, and glomerular compartments. In the interstitium, Cx43 was present as linear or punctate signals of the cell membrane of fibroblasts, in colocalization with pCx43. Cx43‐positive medullary fibroblasts co‐expressed COX‐2. No colocalization was detected between Cx43 and AQP1 or AQP2. Ultrastructural analysis showed Cx43 immunoreactivity at membrane contact zones between fibroblasts and in isolated cell processes of inner medullary interstitium. Cultured fibroblasts showed extensive, punctate Cx43 and pCx43 signals between adjacent cells. Signal was further distributed in non‐junctional areas of plasma membrane, suggesting Cx43 hemichannel functions. Lucifer yellow spread rapidly (10 min) between fibroblasts suggesting intercellular exchange via gap junctions, which was blocked by the gap junctional inhibitor, 18β‐glycyrrhetinic acid.ConclusionsCx43 in rat kidney shows prominent glomerular, vascular, and interstitial distribution, while epithelia, with exception of the podocytes, were negative. Focusing on interstitial fibroblasts, Cx43‐mediated information transfer was demonstrated. A constitutive nature of Cx43 phosphorylation was established in these cells. Our data suggest a cell‐specific heterogeneity of Cx43‐positive gap junctions mediating information exchange among renal cell types.

Colors for Zena by Monica Wellington (review)

Reviewed by: Colors for Zena by Monica Wellington Hope Morrison Wellington, Monica . Colors for Zena; written and illus. by Monica Wellington. Dial, 2013. [32p]. ISBN 978-0-8037-3743-3 $16.99 Reviewed from galleys Ad 4-7 yrs. This picture book embeds a lesson in primary and secondary colors into a simple narrative. When Zena wakes up in a monochromatic house, she wonders where all the colors have gone. And boy, does she find out: in the next spread, she and her dog encounter a world of yellow, in the next a world of red, and in the subsequent spread, orange, the mixture of the two previous hues. Then they encounter a blue spread followed by a yellow spread, followed by—you guessed it—green, and so on. Each time the primary colors mix, the resulting secondary color is announced by something of that color ("'I am yellow and red mixed together,' roars the lion"), thus delivering the lesson directly and accessibly. The concept is somewhat forced, and the accompanying text is slight and overexclamatory. Zena is an enjoyable figure, though, somewhat reminiscent of Dora the Explorer with her bobbed hair, her penchant for adventure, and her constant declarations of enthusiasm ("Red is exciting!" "Magnificent!" "Fantastic!"). The gouache illustrations have a tidy regularity that suggests digital art or even fabric art; each scene wisely counters the key color with black and gray tones, and as the progression continues, escapees from earlier spreads join Zena and add some color variety. The book closes with Zena and her new many-colored friends collaborating on a many-colored painting, and the resulting composition is chock full of colors encountered along the way, providing listeners with a final opportunity to review the color concepts presented. A succinct explanation of the color wheel and some suggested activities for experimenting with color are included. Copyright © 2013 The Board of Trustees of the University of Illinois

Biophysical characterization of gap-junction channels in HeLa cells

HeLa cells seem not to be junctionally coupled when probed with techniques such as Lucifer yellow spreading and/or ionic coupling measured with three inserted microelectrodes. When investigated with double whole-cell patch-clamp measurements, HeLa cells in monolayer cultures were electrically coupled in 39% of the cases with very low transjunctional conductances (average one to five open channels). These gap-junction channels had a single-channel conductance gamma = 26 +/- 6 pS and were voltage-gated with an equivalent gating charge z = 3.1 +/- 1.5 for a voltage of half-maximal inactivation Uo = 49 +/- 10 mV. The voltage-dependent component represents only 31 +/- 8% of the total junctional conductance. The voltage-insensitive conductance is characterized by a residual open probability po (infinity) = 0.34 +/- 0.12, which corresponds to a ratio Gmin/Gmax = 0.50 +/- 0.12. Dissociation of monolayer cells into cell pairs yielded about 58% coupled cell pairs with no notably altered single-channel properties.

Modulation of cell-to-cell coupling between myometrial cells of the human uterus during pregnancy

The purpose of this study was to investigate changes in cell-to-cell coupling of human myometrium during pregnancy to assess the presence and permeability of gap junctions. To evaluate the coupling, input resistance was measured and intercellular spread of Lucifer yellow was observed with microelectrode techniques in intact myometrial preparations from four nonpregnant women, 13 women not in labor, and three women in labor. Octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate were applied to the preparations to assess their effects on cell-to-cell coupling. Input resistance of myometrial cells was decreased (p less than 0.001) and intercellular spread of Lucifer yellow was increased during pregnancy. Octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate rapidly and reversibly increased input resistance (p less than 0.001 for all these agents) and blocked Lucifer yellow spread in tissues from pregnant patients. Cell-to-cell coupling between human myometrial cells is spontaneously improved during pregnancy because of the presence of gap junctions. The coupling is rapidly and reversibly decreased by octanol, isoproterenol, and dibutyryl adenosine 3',5'-cyclic monophosphate as a result of decreased permeability of gap junctions. These two methods of modulation of gap junctions are suggested to be major mechanisms for control of myometrial contractile activity in the human uterus during pregnancy.

Retinoic acid modulates gap junctional permeability: A comparative study of dye spreading and ionic coupling in cultured cells

All- trans retinoic acid (RA), which was recently identified as a morphogen, affects gap junctional permeability in a dose- and time-dependent manner. In five different established mammalian cell lines (FL, BRL, BICR/M1R k, HEL37, BT5C1) 100 μmol/liter RA reduced Lucifer yellow spreading within 30 min to 20–50% of the control. Ionic coupling, however, remained almost unaffected under the same conditions. Freezefractured membranes of untreated and RA-treated cells were similar with regard to frequency and sizes of gap junction plaques. With concentrations of less than 10 μmol/liter RA the dye spreading increased significantly in the human amniotic cell line FL, pointing to a possible modulatory effect of RA on junctional communication.

Der Einfluß der EWG‐Gesetzgebung und ‐Rechtsprechung auf Verwendung und Einsatz von Fetten aus lebensmittelrechtlicher Sicht

AbstractDie bisherige Produktgesetzgebung der EWG trägt der Bedeutung von Fett als wichtigem Nahrungsbestandteil kaum Rechnung. Im horizontalen Bereich regelt die Kennzeichnungsrichtlinie die Verwendung der Klassennamen Öl und Fett im Zutatenverzeichnis. Die Diätrichtlinie schreibt im Rahmen der Nährstoffdeklaration die Angabe des Gesamtfettgehalts diätetischer Lebensmittel vor. Für andere Lebensmittel ist eine Standardisierung freiwilliger Nährwertangaben in Vorbereitung. Die sogenannte Cassis‐Rechtsprechung des Europäischen Gerichtshofes war und ist von erheblich größerem Einfluß. Als Folge eines zum belgischen Recht ergangenen Urteils hat der deutsche Gesetzgeber die Formvorschriften für Margarine‐Packungen aufgehoben und letztlich auch die Butterform freigegeben. Die Aufhebung des Verbots von Milchersatzprodukten für den Bereich des Imports wird zumindest in Teilbereichen auch Folgen für die innerdeutsche Herstellung haben. Die EG‐Dachverbände der Milchwirtschaft und der Margarine‐Industrie schlagen eine Strukturierung des Marktes der gelben Streichfette auf EWG‐Ebene vor. Auch zur Verwendung von Pflanzenfett bei der Herstellung von Speiseeis werden Überlegungen angestellt. Das Verbot des Zusatzes von Fremdfett zu Schokolade konnte Gegenstand eines weiteren Verfahrens vor dem Europäischen Gerichtshof werden. Bei anderen Lebensmitteln, wie z. B. Backwaren, Sauce Hollandaise und Wurst, ist der Einfluß der Verwendung von Pflanzenfett auf die Bezeichnung Gegenstand von Auseinandersetzungen vor nationalen Gerichten, in deren Verlauf der Einfluß des Europarechts immer stärker wird.

Selective illumination of single photoreceptors in the house fly retina: local membrane turnover and uptake of extracellular horseradish peroxidase (HRP) and lucifer yellow.

Single photoreceptor cells in the compound eye of the housefly Musca domestica were selectively illuminated and subsequently compared electron-microscopically with the unilluminated photoreceptors in the immediate surroundings. The rhabdomeres of the illuminated cells remain largely unaffected, but the cells show an increase in the number of coated pits, various types of vesicles, and degradative organelles; some of the latter organelles are described for the first time in fly photoreceptors. Coated pits are found not only at the bases of the microvilli, but also in other parts of the plasma membrane. Degradative organelles, endoplasmic reticulum (ER) and mitochondria aggregate in the perinuclear region. The rough ER and smooth ER are more elaborate, the number of Golgi stacks, free ribosomes and polysomes is increased, and the shape and distribution of heterochromatin within the nuclei are altered. Illuminated photoreceptors also interdigitate extensively with their neighbouring secondary pigment cells. These structural changes in illuminated fly photoreceptor cells indicate an increase in membrane turnover and cellular metabolism. When applied to the eye, Lucifer Yellow spreads into the extracellular space and is taken up only by the illuminated photoreceptor cells. These cells show the same structural modifications as above. Horseradish peroxidase applied in the same way is observed in pinocytotic vesicles and degradative organelles of the illuminated cells. Hence, the light-induced uptake of extracellular compounds takes place in vivo at least partially as a result of an increase in pinocytosis.

Cell lineage of zebrafish blastomeres: I. Cleavage pattern and cytoplasmic bridges between cells

Patterns of cleavage and cytoplasmic connections between blastomeres in the embryo of the zebrafish, Brachydanio rerio have been described. The cell division pattern is often very regular; in many embryos a blastomere's lineage may be ascertained from its position in the cluster through the 64-cell stage. At the 5th cleavage, however, significant variability in pattern is observed, and alternative patterns of the 5th cleavage are described. The early cleavages are partial, incompletely separating blastomeres from the giant yolk cell. The tracer fluorescein-dextran (FD) was injected into blastomeres to learn the extent of the cytoplasmic bridging. It was observed that until the 10th cleavage, blastomeres located along the blastoderm margin maintain cytoplasmic bridges to the yolk cell. Beginning with the 5th cleavage, FD injected into a nonmarginal blastomere either remains confined to the injected cell, or if the injection was early in the cell cycle, the tracer spreads to the cell's sibling, through a bridge persisting from the previous cleavage. On the other hand, injected Lucifer yellow spreads, presumably via gap junctions, widely among blastomeres in a pattern unrelated to lineage.

Voltage-dependent dye coupling at a rectifying electrotonic synapse of the crayfish.

At the crayfish giant motor synapse, the lateral giant axon (l.g.a.) and the giant motor fibre (g.m.f.) form an electrotonic junction which exhibits two states of ionic coupling (Furshpan & Potter, 1959a; Giaume & Korn, 1983). Junctional conductance is low at resting membrane potentials (i.e. with lateral axon more negative than the motor fibre) and high when the polarity of the voltage difference (delta V) across the synapse is reversed. For these two states of conductance, junctional permeability was investigated using the intercellular tracer Lucifer Yellow. The dye was ionophoretically injected into either the presynaptic (l.g.a.) or the post-synaptic (g.m.f.) cell. In the high conductance state (delta V greater than 0), fluorescence was detected in both neurones whether Lucifer Yellow had been injected pre- or post-synaptically. By contrast, at the resting junctional polarization (delta V less than 0) Lucifer Yellow spread from the giant axon to the g.m.f., but not from the g.m.f. to the giant axons. These data demonstrate that dye transfer at the giant motor synapse, like ionic coupling, is sensitive to junctional polarization and is more marked in the high conductance state. Possible explanations for the asymmetry observed in the low conductance state are discussed.

Electrical potentials and cell-to-cell dye movement in mouse mammary gland during lactation.

Stable potentials were recorded with microelectrodes in an in vivo preparation of the mammary gland from the anesthetized lactating mouse. Location of the microelectrode tip was determined by ionophoretic injection of the fluorescent dye Lucifer yellow CH. Fifteen dye injections were localized to mammary alveolar cells; the average recorded potential for these penetrations was -49 +/- 2 mV. Cell-to-cell dye transfer between alveolar cells was observed with all intracellular Lucifer yellow injections. Ten dye injections were localized to the alveolar lumina with an average recorded potential of -35 +/- 2 mV. With these penetrations Lucifer yellow spread rapidly to many alveolar lumina. These findings indicate that stable potentials can be obtained from both cells and lumina in the in vivo mammary gland, demonstrating the feasibility of electrophysiological studies of the mammary epithelium. The presence of a large transepithelial potential provides evidence for physiologically tight junctions between mammary alveolar cells. In addition, the distribution of Lucifer yellow shows that mammary alveolar cells are coupled and suggests that milk flows freely between alveolar lumina.

Experiments on the time of application of insecticide to decrease the spread of yellowing viruses of sugar beet, 1954‐66

SUMMARYSprays of demeton‐methyl insecticide decreased the spread of yellowing viruses by aphids in sugar‐beet crops in England. Between 1957 and 1960, when yellows was prevalent, the incidence, assessed as ‘infected‐plant‐weeks’, was decreased by 36–41 % by one spray, depending on when it was applied, and by 55 % by two sprays, giving average yield increases of 1½ and 2 ton/acre of roots respectively. Between 1962 and 1966, when yellows spread less, a spray at the time when growers were advised to spray by the British Sugar Corporation decreased yellows incidence by 37 %, whereas sprays 2 weeks earlier or later decreased it by 24 % and 25 % respectively. Between 1958 and 1966 an annual average of 160000 of the country's 440000 acres of sugar beet has been sprayed, often to control Aphis fabae as well as to check the spread of yellows. A spray gives a profitable yield increase when yellows incidence in unsprayed plots is 20 % at the end of August.