Mendelian Genes and Rates of Development in Gammarus Chevreuxi

1927 ◽  
Vol 5 (2) ◽  
pp. 112-134 ◽  
Author(s):  
E. B. FORD ◽  
J. S. HUXLEY
Keyword(s):  
Cross Section ◽  
Equilibrium Position ◽  
Low Temperatures ◽  
Sexual Maturity ◽  
Red Pigment ◽  
Wild Type ◽  
Pigment Formation ◽  
Melanin Formation ◽  
Complete Saturation ◽  
Theoretical Considerations

In the present paper the following facts and theoretical considerations have been brought forward: (1) All the mutations so far examined which influence the colour of the facets (as opposed to total absences of black and red pigment) in the eyes of Gammarus chevreuxi appear to act by modifying the time relationships governing the deposition of melanin. (2) All coloured eyes are at first colourless, and then become scarlet owing to the formation of a red pigment soluble in alcohol; later they may darken by the deposition of melanin. (3) In the normal black eye (RR), melanin begins to be deposited about 2 days before hatching (at 23° C ) ; its deposition is very rapid, and complete saturation, giving a dense black colour, is reached at or about extrusion. (4) In red (rr) eyes the time of onset and the rate of melanin formation is always slower. The rate may be modified by a factor "s" slowing it down considerably, and a factor "m" slowing it down to a less degree. (5) At 23° C. rrSSMM eyes begin to darken at about 4 to 6 days after extrusion, and reach an equilibrium position (of a deep chocolate colour) in about 3 weeks. (6) Under the same conditions, rrssMM eyes begin to darken at about 4 to 8 days, and reach an equilibrium (of a lighter chocolate shade) in about 5 to 7 weeks. The degree of phenotypic divergence between the colours of rrSS and rrss is at first nil; it then increases to a maximum at about 2½ to 3 weeks from extrusion, after which it diminishes once more. It is, however, not completely obliterated in the adult. (7) In addition a factor "d" has been found which delays the onset of rapid pigment development until sexual maturity. The rate of subsequent darkening is that characteristic of the other factors present. (8) Other agencies also influence melanin formation. In rr eyes melanin is formed rapidly at 23° C. (above which temperature the stocks are unhealthy), less rapidly at 20° C., and only to a slight extent, beginning after about four months, at or below 14° C. (9) In RR (wild type and black-no-white) eyes, however, low temperatures merely cause a slight delay in melanin formation. (10) The area of the eye also influences the colour. The eye facets continue to increase in size after the melanin has attained its equilibrium position. Thus the same amount of pigment is spread over a greater area, and the eye appears slightly paler. This again does not apply to RR eyes, presumably owing to the large quantity of black pigment formed. New facets are added so long as growth continues. Since they behave as distinct units in pigment formation, those which have appeared most recently will be bright red while the older ones are already blackish. (11) Other instances are given of genes which appear to control rates of development in various animals. (12) It is suggested that the effects of multiple allelomorph series (e.g. for eye-colour in Drosophila) may represent a cross-section through a series of developmental curves of one and the same substance, the curves differing as regards rates of formation of the substance, times of onset of deposition, and final level of the equilibrium position obtained.

Ultrastructure of Melanin Formation in Curvularia sp., Alternaria sp., and Drechslera Sorokiniana

1977 ◽  
Vol 35 ◽  
pp. 398-399
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
A. A. Bell
Keyword(s):  
Potassium Phosphate ◽  
Thielaviopsis Basicola ◽  
Wild Type ◽  
Potassium Phosphate Buffer ◽  
Transmission Microscopy ◽  
Electron Transmission ◽  
Melanin Formation ◽  
Before And After ◽  
Alternaria Sp ◽  
Electron Transmission Microscopy

(+)-Scytalone [3,4-dihydro-3,6,8-trihydroxy-l-(2Hj-naphthalenone] and 1,8-di- hydroxynaphthalene (DHN) have been proposed as intermediates of melanin synthesis in the fungi Verticillium dahliae (1, 2, 3, 4) and Thielaviopsis basicola (4, 5). Scytalone is enzymatically dehydrated by V. dahliae to 1,3,8-trihydroxynaphthalene which is then reduced to (-)-vermelone [(-)-3,4- dihydro-3,8-dihydroxy-1(2H)-naphthalenone]. Vermelone is subsequently dehydrated to DHN which is enzymatically polymerized to melanin.Melanin formation in Curvularia sp., Alternaria sp., and Drechslera soro- kiniana was examined by light and electron-transmission microscopy. Wild-type isolates of each fungus were compared with albino mutants before and after treatment with 1 mM scytalone or 0.1 mM DHN in 50 mM potassium phosphate buffer, pH 7.0. Both chemicals were converted to dark pigments in the walls of hyphae and conidia of the albino mutants. The darkened cells were similar in appearance to corresponding cells of the wild types under the light microscope.

Prosurvival and antiapoptotic effects of PGE2in radiation injury are mediated by EP2 receptor in intestine

2003 ◽  
Vol 284 (3) ◽  
pp. G490-G498 ◽  
Author(s):  
Courtney W. Houchen ◽  
Mark A. Sturmoski ◽  
Shrikant Anant ◽  
Richard M. Breyer ◽  
William F. Stenson
Keyword(s):  
Stem Cell ◽  
Cell Survival ◽  
Cross Section ◽  
Radiation Injury ◽  
Biological Activities ◽  
Receptor Expression ◽  
Apoptotic Cells ◽  
Wild Type ◽  
Γ Irradiation ◽  
Stem Cell Survival

The biological activities of PGE2 are mediated through EP receptors (EP1–EP4), plasma membrane G protein-coupled receptors that differ in ligand binding and signal-transduction pathways. We investigated gastrointestinal EP2 receptor expression in adult mice before and after radiation injury and evaluated intestinal stem cell survival and crypt epithelial apoptosis after radiation injury in EP2 null mice. EP2 was expressed throughout the gut. Intestinal EP2 mRNA increased fivefold after γ-irradiation. Crypt survival was diminished in EP2 −/− mice (4.06 crypts/cross section) compared with wild-type littermates (8.15 crypts/cross section). Radiation-induced apoptosis was significantly increased in EP2 −/− mice compared with wild-type littermates. Apoptosis was 1.6-fold higher in EP2 −/− mice (5.9 apoptotic cells/crypt) than in wild-type mice (3.5 apoptotic cells/crypt). The EP2receptor is expressed in mouse gastrointestinal epithelial cells and is upregulated following radiation injury. The effects of PGE2on both crypt epithelial apoptosis and intestinal crypt stem cell survival are mediated through the EP2 receptor.

scholarly journals Convergent evolution of a novel blood-red nectar pigment in vertebrate-pollinated flowers

2021 ◽  
Author(s):  
Rahul Roy ◽  
Nickolas Moreno ◽  
Stephen A Brockman ◽  
Adam Kostanecki ◽  
Amod Zambre ◽  
...  
Keyword(s):  
Convergent Evolution ◽  
Alcohol Oxidase ◽  
Enzymatic Activities ◽  
Red Pigment ◽  
Pollinator Visitation ◽  
Pigment Formation ◽  
Red Color ◽  
Genes Encoding ◽  
Pigment Precursor ◽  
Imine Bond

Nesocodon mauritianus (Campanulaceae) produces a blood-red nectar that has been proposed to serve as a visual attractant for pollinator visitation. Here we show that the red color of the nectar is derived from a novel alkaloid termed nesocodin. The first nectar produced is acidic and pale yellow in color, but slowly becomes alkaline before taking on its characteristic red color. Three enzymes secreted into the nectar are either necessary or sufficient for pigment production, including (1) a carbonic anhydrase that creates an alkaline environment, (2) an aryl alcohol oxidase that generates sinapaldehyde, a pigment precursor, and (3) a ferritin-like catalase that protects nesocodin from degradation by hydrogen peroxide. Our findings demonstrate how these three enzymatic activities allow for the condensation of sinapaldehyde and proline to form a novel pigment with a stable imine bond, which in turn is attractive to Phelsuma geckos, the presumed pollinators of Nesocodon. We also identify nesocodin in the red nectar of the distantly related Jaltomata herrerae and provide evidence for convergent evolution of this trait. While the overall enzymatic activities required for red pigment formation in both Nesocodon and J. herrerae nectars are identical, the associated genes encoding the enzymes are not orthologous and, in the case of the aryl alcohol oxidase, even belong to different protein families. This work cumulatively identifies a novel, convergently evolved trait in two vertebrate-pollinated species, suggesting the red pigment is selectively favored and that only a limited number of compounds are likely to underlie this adaptation.

Effect of temperature on transition and transversion mutagenesis: characterization of wild type and a mutator T4 DNA polymerase mutant

1984 ◽  
Vol 26 (3) ◽  
pp. 386-389 ◽  
Author(s):  
Linda J. Reha-Krantz ◽  
Sükran Parmaksizoglu
Keyword(s):  
Dna Polymerase ◽  
Low Temperatures ◽  
Bacteriophage T4 ◽  
Effect Of Temperature ◽  
In Vitro Mutagenesis ◽  
Wild Type ◽  
Mutational Site

The effect of temperature on genetically well-defined mutational pathways was examined in the bacteriophage T4. The mutational site was a T4 rII ochre mutant which could revert to rII+ via a transversion or to the amber convertant via a transition. Temperature did not strongly affect any of the pathways examined in a wild-type background; however, increased temperature reduced the mutational activity of a mutator DNA polymerase mutant. Possible models to explain the role of temperature in mutagenesis are discussed as well as the significance of low temperatures for in vitro mutagenesis reactions.Key words: bacteriophage T4, mutator, transition, transversion, temperature effects.

NEW LOCI IN DICTYOSTELIUM DISCOIDEUM DETERMINING PIGMENT FORMATION AND GROWTH ON BACILLUS SUBTILIS

Genetics ◽  
1980 ◽  
Vol 96 (1) ◽  
pp. 115-123
Author(s):  
James H Morrissey ◽  
Steven Wheeler ◽  
William F Loomis
Keyword(s):  
Bacillus Subtilis ◽  
Dictyostelium Discoideum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Wild Type ◽  
Linkage Groups ◽  
New Mutation ◽  
Pigment Formation ◽  
Complementation Groups ◽  
First Time

ABSTRACT Seventeen independently isolated pigmentless (white) mutations in Dictyostelium discoideum are all recessive and fall into three complementation groups identifying two new whi loci in addition to the previously characterized whiA locus. whiB and whiC map to linkage groups III and IV, respectively. In addition, it was discovered that our laboratory stock of NC4, the wild-type strain from which these mutants were derived, has spontaneously lost the ability to grow on Bacillus subtilis. This new mutation, bsgB500, maps to linkage group VII and is not allelic to bsgA. bsgB500 is the first spontaneously derived mutation in D. discoideum that can be used to select heterozygous diploids, and for the first time allows genetic analysis to be routinely performed on strains derived from an unmutagenized background.

scholarly journals Unbeeinflußbarkeit ihrer Wirkung auf Ribonuclease durch Cystamin und tiefe Temperaturen

1966 ◽  
Vol 21 (12) ◽  
pp. 1165-1170 ◽  
Author(s):  
H. Jung
Keyword(s):  
Cross Section ◽  
Low Temperatures ◽  
Room Temperature ◽  
High Efficiency ◽  
Reduction Factor ◽  
Biological Damage ◽  
Nuclear Collisions ◽  
Different Temperatures ◽  
Fast Protons ◽  
Mev Protons

Slow protons having energies below 1.5 keV dissipate their kinetic energy in matter through elastic nuclear collisions. By this process atoms are displaced out from their original positions in macromolecules. This was recently shown to cause biological damage with high efficiency. Experiments are described to test the possibility of modifying the sensitivity of ribonuclease towards elastic collisions by protective agents and by low temperatures. When cystamine is present during irradiation dry ribonuclease is protected against the action of “ionizing” fast protons (2 MeV), the dose reduction factor being 1.8. But no protection is observed when inactivation is achieved by elastic nuclear collisions (proton energy 1 keV and 1.4 keV). Similar results were obtained when the irradiations were carried out at different temperatures. Using 2 MeV protons the radiosensitivity of ribonuclease was found to be 3 times higher at room temperature than at 125 °K, but when using slow protons of 1.4 keV energy the inactivation cross section turned out to be independent of temperature. This shows that the action of elastic nuclear collisions can be modified neither by cystamine nor by low temperatures.

Vibronische Kopplung und dynamisch verzerrte Strukturen in Hexahalogenotelluraten(IV): Ergebnisse aus Tieftemperatur-Röntgenbeugungsuntersuchungen (300—160 K) und aus FTIR-spektroskopischen Experimenten (300—5 K) [1] / Vibronic Coupling and Dynamically Distorted Structures in Hexahalogenotellurates(IV): Low Temperatur X-Ray Diffraction (300—160 K) and FTIR-Spectroscopic (300—5 K) Results [1]

1987 ◽  
Vol 42 (10) ◽  
pp. 1273-1281 ◽  
Author(s):  
Walter Abriel ◽  
Ernst-Jürgen Zehnder
Keyword(s):  
Ground State ◽  
Low Temperatures ◽  
Potential Surface ◽  
Energy Gap ◽  
Vibronic Coupling ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Excited State ◽  
Theoretical Considerations

AbstractFrom theoretical considerations a dynamically distorted octahedron as a result of vibronic coupling between the ground state and the first excited state should exist for 14 electron AX6E systems like TeX62- . A high symmetry crystal field yielding at least a center of symmetry for the Te position stabilizes this fluctuating structure, otherwise statical distortion will be observed. From X-ray diffraction experiments on antifluorite type compounds A2TeX6 (A = Rb. Cs: X = Cl, Br) the averaged structure (m3̅m symmetry) of the anions was found even at very low temperatures. The thermal parameters are not significantly different from those of similar SnX62 compounds. Distortions therefore are very small and are evident from FTIR spectroscopic meas­urements only. Here very broad T1u-deformation vibration bands are observed down to tempera­tures <10 K without splitting: Astatically distorted species could not be frozen out. In contrast to XeF6 for TeX62- the energy gap between the threefold, fourfold or sixfold minima of the potential surface (according to the symmetry of one component of the T1u-vibration) is very small and shifted to temperatures lower than reached with the devices used for these experiments.

Equilibrium radial positions of neutrally buoyant spherical particles over the circular cross-section in Poiseuille flow

2017 ◽  
Vol 813 ◽  
pp. 750-767 ◽  
Author(s):  
Yusuke Morita ◽  
Tomoaki Itano ◽  
Masako Sugihara-Seki
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Poiseuille Flow ◽  
Equilibrium Position ◽  
Probability Function ◽  
Circular Cross Section ◽  
Spherical Particles ◽  
Inertial Migration ◽  
Entry Length ◽  
Neutrally Buoyant

An experimental study of the inertial migration of neutrally buoyant spherical particles suspended in the Poiseuille flow through circular tubes has been conducted at Reynolds numbers $(Re)$ from 100 to 1100 for particle-to-tube diameter ratios of ${\sim}$0.1. The distributions of particles in the tube cross-section were measured at various distances from the tube inlet and the radial probability function of particles was calculated. At relatively high $Re$, the radial probability function was found to have two peaks, corresponding to the so-called Segre–Silberberg annulus and the inner annulus, the latter of which was first reported experimentally by Matas et al. (J. Fluid Mech. vol. 515, 2004, pp. 171–195) to represent accumulation of particles at smaller radial positions than the Segre–Silberberg annulus. They assumed that the inner annulus would be an equilibrium position of particles, where the resultant lateral force on the particles disappears, similar to the Segre–Silberberg annulus. The present experimental study showed that the fraction of particles observed on the Segre–Silberberg annulus increased and the fraction on the inner annulus decreased further downstream, accompanying an outward shift of the inner annulus towards the Segre–Silberberg annulus and a decrease in its width. These results suggested that if the tubes were long enough, the inner annulus would disappear such that all particles would be focused on the Segre–Silberberg annulus for $Re<1000$. At the cross-section nearest to the tube inlet, particles were absent in the peripheral region close to the tube wall including the expected Segre–Silberberg annulus position for $Re>700$. In addition, the entry length after which radial migration has fully developed was found to increase with increasing $Re$, in contrast to the conventional estimate. These results may be related to the developing flow in the tube entrance region where the radial force profile would be different from that of the fully developed Poiseuille flow and there may not be an equilibrium position corresponding to the Segre–Silberberg annulus.

scholarly journals apd1  +, a Gene Required for Red Pigment Formation in ade6 Mutants of Schizosaccharomyces pombe, Encodes an Enzyme Required for Glutathione Biosynthesis: A Role for Glutathione and a Glutathione-Conjugate Pump

Genetics ◽  
1997 ◽  
Vol 145 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Biswendu Chaudhuri ◽  
Susham Ingavale ◽  
Anand K Bachhawat
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Schizosaccharomyces Pombe ◽  
Biosynthetic Pathway ◽  
Glutathione Synthetase ◽  
Red Pigment ◽  
Genetic Investigation ◽  
Pigment Formation ◽  
Glutathione Conjugate ◽  
Glutathione Biosynthesis ◽  
Glutamylcysteine Synthetase

Mutants in the adenine biosynthetic pathway of yeasts (ade1 and ade2 of Saccharomyces cerevisiae, ade6 and ade7 of Schizosaccharomyces pombe) accumulate an intense red pigment in their vacuoles when grown under adenine-limiting conditions. The precise events that determine the formation of the pigment are however, still unknown. We have begun a genetic investigation into the nature and cause of pigmentation of ade6 mutants of S. pombe and have discovered that one of these pigmentation defective mutants, apd1 (adenine pigmentation defective), is a strict glutathione auxotroph. The gene apd1  + was found to encode the first enzyme in glutathione biosynthesis, γ-glutamylcysteine synthetase, gcs1  +. This gene when expressed in the mutant could confer both glutathione prototrophy and the characteristic red pigmentation, and disruption of the gene led to a loss in both phenotypes. Supplementation of glutathione in the medium, however, could only restore growth but not the pigmentation because the cells were unable to achieve sufficient intracellular levels of glutathione. Disruption of the second enzyme in glutathione biosynthesis, glutathione synthetase, gsh2  +, also led to glutathione auxotrophy, but only a partial defect in pigment formation. A reevaluation of the major amino acids previously reported to be present in the pigment indicated that the pigment is probably a glutathione conjugate. The ability of vanadate to inhibit pigment formation indicated that the conjugate was transported into the vacuole through a glutathione-conjugate pump. This was further confirmed using strains of S. cerevisiae bearing disruptions in the recently identified glutathione-conjugate pump, YCF1, where a significant reduction in pigment formation was observed. The pump of S. pombe is distinct from the previously identified vacuolar pump, hmt1p, for transporting cadystin peptides into vacuoles of S. pombe.

scholarly journals Photolysis of frozen iodate salts as a source of active iodine in the polar environment

2016 ◽  
Vol 16 (19) ◽  
pp. 12703-12713 ◽  
Author(s):  
Óscar Gálvez ◽  
M. Teresa Baeza-Romero ◽  
Mikel Sanz ◽  
Alfonso Saiz-Lopez
Keyword(s):  
Cross Section ◽  
Low Temperatures ◽  
Atmospheric Model ◽  
Ir Absorption ◽  
Absorption Cross ◽  
Solar Simulator ◽  
Near Ultraviolet ◽  
Polar Environment ◽  
Liquid Solutions ◽  
Ir Bands

Abstract. Reactive halogens play a key role in the oxidation capacity of the polar troposphere. However, sources and mechanisms, particularly those involving active iodine, are still poorly understood. In this paper, the photolysis of an atmospherically relevant frozen iodate salt has been experimentally studied using infrared (IR) spectroscopy. The samples were generated at low temperatures in the presence of different amounts of water. The IR spectra have confirmed that, under near-ultraviolet–visible (UV–Vis) radiation, iodate is efficiently photolysed. The integrated IR absorption coefficient of the iodate anion on the band at 750 cm−1 has been measured to be A  =  9.8 ± 0.5  ×  10−17 cm molecule−1. The photolysis rate of the ammonium iodate salt was measured by monitoring the decay of ammonium or iodate IR bands (1430 and 750 cm−1 respectively) in the presence of a solar simulator. The absorption cross section of the liquid solutions of ammonium iodate at wavelengths relevant for the troposphere (250 to 400 nm) has been obtained and used to estimate the photolytic quantum yield for the frozen salt. Finally, using an atmospheric model, constrained with the experimental data, we suggest that the photolysis of iodate in frozen salt can potentially provide a pathway for the release of active iodine to the polar atmosphere.

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