Lichtinduzierte Farbstoffbildung bei Saccharomyces cerevisiae var. ellipsoideus

Zusammenfassung Die lichtinduzierte Pigmentbildung wird in Abhängigkeit von verschiedenen Faktoren untersucht und ihre Kinetik gemessen. Der Farbstoff entsteht nur in einem stickstoffhaltigen Medium. — Der Temperaturbereich, innerhalb dessen Pigmentbildung möglich ist, liegt zwischen 14° und 39° C mit einem Optimum bie 29° C. — Für die Anfangskonzentration von Glucose im Medium wird ein Optimum bei 3% gefunden. Nach Verbrauch der Glucose hört die Farbstoffbildung auf, sofern nicht ein anderer Faktor begrenzend wirkt wie z. B. hohe Lichtintensität, durch die die Pigmentproduktion stark eingeschränkt, schließlich sogar völlig verhindert wird. In Abhängigkeit von der Lichtintensität findet sich ein Optimum der Pigmentbildung je nach Lichtsensibilität der Zellen zwischen 26 und 45 kerg · sec^-1 · cm^-2. Hohe Lichtintensität wirkt zerstörend auf bereits entstandenes Pigment. — Die Aktivität des pigmentbildenden Systems sowie die erreichbare Farbstoffendkonzentration hängen ferner vom Beginn der Belichtung ab. Nennenswerte Pigmentsynthese ist nur möglich bei einem Belichtungsbeginn innerhalb der ersten 10–12 Std und ist um so intensiver, je früher die Belichtung einsetzt. — Bei im übrigen günstigen Kulturbedingungen arbeitet das pigmentbildende System nur während der Lichteinwirkung. — Kinetische Untersuchungen der Farbstoffbildung zeigen, daß das Pigment im Medium entsteht und von dort in die Zellen aufgenommen wird. Demnach muß eine Synthese von Pigmentvorstufen in den Zellen und ihre Abgabe an das Medium angenommen werden.

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Light-induced pigment production by Saccharomyces cerevisiae var. ellipsoideus Physiology of pigment production

Summary Light-induced pigment synthesis by cells of Saccharomyces cerevisiae var. ellipsoideus is investigated under the influence of various factors, and kinetic studies of its formation are performed. Pigmentation only occurs with nitrogen in the medium. The temperature favouring pigment production ranges between 14° C and 39° C, and has its optimum at 29° C. Optimum glucose concentration in the medium is 3%. Pigment formation continues until glucose is completely exhausted provided that no other factor — as for instance high light intensity — limits pigment synthesis before. The lowest possible light intensity for pigment production was found at 3 kerg · sec^-1 · cm^-2, the optimum lies between 26 and 45 kerg ¢ sec^-1 · cm^-2 — depending on the light sensibility of the cells. Still higher light intensities finally destroy part of the pigment already formed. — There is a clear influence of the onset of light exposure a) on the activity of the pigment producing system and b) on the end concentration of pigment. Only cells exposed to light within the first 10–12 hours of culture give rise to considerable pigment synthesis which is the more active the more the onset of light approaches that of the culture. If all other factors are favourable the pigment producing system once working continues to do so only as long as light is on. —Kinetic experiments show the pigment to be formed in the medium and then to be incorporated by the cells. It must be concluded therefore that pigment precursors are synthesised in the cell and from there transferred into the medium.

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Herrn Prof. Dr. W. Simonis zum 60. Geburtstag gewidmet.     

Amöboid bewegliche Pigmentzellen im Epithel des Seeigels Centrostephanus longispinus

Zusammenfassung Für den physiologischen Farbwechsel bei Vertebraten und Evertebraten gilt die Vorstellung, daß eine Pigmentbewegung innerhalb einer formkonstanten Zelle stattfindet. Am Seeigel Centrostephanus longispinus wird nun der Nachweis einer amoeboiden Bewegung von Pigmentzellen geführt: Die Epidermis von Centrostephanus enthält große braune Chromatophoren, die bei Belichtung eine Pigmentdispersion, bei Verdunkelung eine Konzentration des Pigments zeigen. Die Chromatophoren sind außerordentlich stark verzweigte Zellen, deren Arme dicht mit Pigmentgrana erfüllt sind. Im geballten Zustand ist die allgemeine Zellform mehr oder weniger ovoid, wobei die Zellarme eingezogen und dicht um die Zellmitte angeordnet sind. Dispersion des Pigments wird hervorgerufen durch Ausstrecken der pigmentierten Zellarme in den Interzellularraum des umgebenden Gewebes. Innerhalb der Zelle werden filamentöse Elemente nachgewiesen, die vermutlich für die Zellbeweglichkeit verantwortlich sind. — Ferner wird der zelluläre Aufbau des Integuments beschrieben.

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Amoeboid pigment cells in the epithelium of the sea urchin Centrostephanus longispinus A novel colour change mechanism

Summary Rapid colour changes in vertebrate and invertebrate species are considered to be due to movement of pigment granules within pigment cells of constant shape. Evidence is presented in this study to show that an amoeboid movement of chromatophores occurs in the epidermis of the Echinoderm Centrostephanus longispinus. The epidermis in this species contains large brown chromatophores, which display a dispersion of pigment on illumination and its concentration on darkening. The chromatophores are extensively branched cells, and their branches are densely packed with pigment granules. In the state of pigment concentration, the shape of the cell is more or less ovoid, and the cell branches are drawn in and closely arranged around the cell centre. Dispersion is attained by a stretching out of the pigmented cell branches into the intercellular spaces of the surrounding tissue. Within the cell, filamentous elements, which may be functional in the motility of the pigment cell, can be demonstrated.—Additionally the cellular composition of the integument is described.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. Frl. A. Mikolaczick danken wir für sorgfältige technische Assistenz.     

Feinstrukturen im komplexauge der blattschneiderbiene Megachile rotundata (F.) (hymenoptera,apidae)

Zusammenlassung Es wurden Ommatidien der dorsalen Augenhälfte von Megachile-, einer solitären Bienenart, elektronenmikroskopisch untersucht. Die Kristallkegelmasse der Semperschen Zellen (euconer Typ) stößt in breiter Front an die Cornealinse und bildet dadurch gegenüber anderen euconen Augen vermutlich ein verbessertes optisches System. Die 4 Fortsätze der Semperschen Zellen ziehen bis zur Basalmembran, wo she anschwellen und dicht mit Schirmpigment gefüllt sind.Die Hauptpigmentzellen enden distal in einem schmalen Bereich an der Cornea, proximal kurz unterhalb vom Kristallkegel. Die Nebenpigmentzellen rind in ihrem gesamten Verlauf von der Cornea bis zur Basalmembran mit Pigmentgrana angefüllt. Die bei Apis beschriebene basale Pigmentzelle jedes Ommatidiums gibt es bei Megachile nicht. An ihre Stelle treten die erwähnten basalen Anschwellungen der Fortsätze der Semperschen Zellen.Die Retinulae bestehen aus je 9 Sehzellen. Sie bilden ein Rhabdom vom geschlossenen Typ, das im distalen Teil des Ommatidiums aus den in der Mitte sich breitflächig berührenden und gleichartig ausgerichteten Mikrovilli der beiden Sehzellen Nr. 1 und 5 besteht. Diese beiden Rhabdomere werden auf der einen Seite von den Rhabdomeren der Zellen 2–4, auf der anderen von denen der Zellen 6–8 flankiert, die wiederum allesamt gleichartig, jedoch rechtwinklig zu ersteren angeordnet sind.Basalwärts folgt ein Bereich, in dem rich die Rhabdomere der Sehzellen 2–4 und 6–8 verlängern, wobei sich 3 und 7 breit berÜhren. Die Mikrovilli der Zellen 1 und 5 erscheinen an die Peripherie abgedrängt. Die 9. Retinulazelle ist im basalen Drittel am Rhabdom beteiligt.Die Pigment- und Semperschen Zellen besitzen außer den üblichen Organellen Centriolen, gewinkelt angeordnet oder in Tandem-Stellung. In den Retinulazellen entsprechen these den Basalkörpern von Cilien, die nach distal Tubuli (gelegentlich werden auch Fibrillen mit periodischen Strukturen gefunden) aussenden, nach basal dagegen Wurzelfibrillen, die sich zu einem Wurzelfaden vereinigen. — Die Ergebnisse werden diskutiert und vor allem mit denen, die an Apis erzielt werden, verglichen.

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Fine structure of the compound eye in the leaf-cutter bee Megachile rotundata (F.) (hymenoptera, apidae)

Summary Ommatidia in the dorsal part of the compound eye in female Megachile (a solitary bee) were studied with the electron microscope. The crystalline conesubstance of the Semper (type cells eucone) borders a wide area of the cornea, which probably implies an improved optical system compared with other eucone eyes. The four processes of the Scraper cells extend to the basement membrane, where they enlarge and are filled with screening pigment. The iris pigment cells end distally by impinging on a small area of the cornea and (unlike other ommatidia with an eucone form of crystalline cone) they do not overlap the corneal cells. The retinal pigment cells are entirely filled with pigment granules. A basal pigment cell as described in each ommatidium in Apis does not occur in Megachile. Instead, one finds the basal swellings of the Semper cell processes mentioned above.Usually the retinula consists of nine retinular cells arranged in a closed rhabdom. In the distal part of the ommatidium, this rhabdom is built by microvilli of the retinular cells number 1 and 5, aligned in one direction each perpendicular to the next. These two rhabdomeres are bordered on one side by the rhabdomeres of cell 2–4, and on the other side by those of cells 6–8. Again, these rhabdomeres are all aligned in one direction perpendicular to that of cell 1 and 5. Further down towards the base, there is an area in which the rhabdomeres of the retinular cells 2–4 and 6–8 face another as mentioned above, whereas those microvilli belonging to cell 1 and 5 seem to be forced away towards the periphery of the rhabdom.In addition to common organelles, both the pigment cells and Semper cells contain centrioles arranged at an angle or in tandem. In the retinular cells, they correspond to the basal bodies of cilia, and they give rise to tubules (sometimes striated fibrils are found). However, towards to base they give rise to striated fibrils which unite in a root fibre. — The results are discussed and compared with those known of Apis.

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Fur ihre technische Hilfe danken wir besonders herzlich Frl. A. Hennig.     

The fungal bladders of the endocyanosisGeosiphon pyriforme,aGlomus-related fungus: cell wall permeability indicates a limiting pore radius of only 0.5 nm

Summary Geosiphon pyriforme, a consortium of aGlomiw-like fungus andNostoc spp., forms syncytial, up to 2 mm long bladders accommodating the endosymbiotic cyanobacteria. The bladders are bordered by an elastic cell wall and have a turgor of about 0.6 MPa, as measured by piercing them with oil filled microcapillaries within different osmolarities of sorbitol. In the presence of certain organic osmolytes in the surrounding medium, the bladders collapsed, i.e., showed cytorrhysis. We studied systematically the cytorrhytic effectivity of the diverse osmolytes in relation to their hydrodynamic molecule radii by a solute-exclusion method with living bladders and those which have been extracted by different methods. The results suggest that the cell wall of the bladders has an unusually small limiting pore size thus representing an effective diffusion barrier for glucose and is virtually impermeable for sucrose for at least 8 h. The pore radii of the cell wall are estimated to be about 0.5 nm. Na₂CO₃ extraction, frequently used to partially extract pectic substances from plant cell walls, strongly increases wall permeability. Electron microscopic observations show an electron-dense outer cell wall layer, perhaps responsible for the low permeability. The finding that the cell wall of theGeosiphon bladders represents an effective osmotic barrier provides not only new insights into the cell physiology ofGeosiphon but may also contribute more generally to a better understanding of the mechanisms of selectivity of transport across the cell walls of AM fungi.Abbreviations AM arbuscular mycorrhiza - DMSO dimethyl sulfoxyde - EDTA ethylenediaminetetraacetic acid - PEG polyethylene glycol - res Einstein-Stokes hydrodynamic radius     

Costs of carnivory in the common bladderwort,Utricularia macrorhiza

Summary Carnivorous plants are usually restricted to nutrient-poor environments, suggesting that there is a cost to caputuring animals that is offset by the benefits of carnivory only under unusual circumstances. One such cost could involve a reduced photosynthetic capacity associated with the growth and maintenance of prey-capture organs. This hypothesis is tested using the common bladderwort, Utricularia macrohiza, which bears numerous distinct prey-capture bladders. Measurements of the photosynthetic and respiration rates of leaves and bladders were incorporated into growth models to estimate the growth rates of plants with and without bladders. Comparisons were made in three lakes which differed in nutrient status and in which plants exhibited marked differences in their densities of prey-capture bladders. Overall, photosynthetic rates for leaves were approximately twice those for bladders while respiration rates did not differ significantly between tissues. Calculations incorporating these values indicate that plants producing both bladders and leaves would grow to as little as 21% or as much as 83% of plants that produced leaves alone. Comparisons among lakes led to the rejection of the hypothesis that plants from some lakes are able to produce more bladders per leaf because bladders differ in their photosynthetic productivity.     

Beschleunigung der „Dunkeladaptation“ eines UV-Rezeptors durch sichtbare Strahlung

Zusammenfassung Elektrophysiologische Untersuchungen über das adaptive Verhalten der UV-Rezeptoren von Ascalaphus im Frontalauge zeigten, daß die Empfindlichkeit nach UV-Helladaptation durch Strahlung des sichtbaren Bereichs zwischen 420 und 550 nm erheblich beschleunigt wird. Die Wellenlänge 589 erwies sich als nahezu unwirksam, Strahlung im Bereich zwischen 460 und 480 nm war am wirksamsten. Die spektrale Empfindlichkeit für die regenerative Wirkung der sichtbaren Strahlung ist identisch mit der spektralen Absorptionswahrscheinlichkeit des thermostabilen Folgefarbstoffes B. Aus der spektralen Verteilung des Himmelslichtes und der spektralen Absorptionswahrscheinlichkeit für den UV-Sehfarbstoff und seinem Folgefarbstoff wird abgeleitet, daß der UV-Rezeptor ohne jede chemische Resynthese des Sehpigments, allein durch Quantenabsorption, seine Empfindlichkeit zu steuern vermag. Wie beim Tintenfischrezeptor (Eledone) wird das Rezeptorpotential nur durch Treffer am Ausgangsfarbstoff ausgelöst, nicht durch Treffer am Folgefarbstoff B.

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Acceleration of dark-adaptation by visible light in UV-receptors

Summary The adaptation of the ultra-violet (UV) receptors in the frontaleye of the insect Ascalaphus (Neuroptera) was studied by electrophysiological techniques. The measurements showed that the sensitivity increase after illumination by an UV adapting light is considerably accelerated by exposure to visible light with wavelengths between 420 and 550 nm (Figs. 1, 2). Most effective are the wavelengths between 460 and 480 nm (Table 1). The wavelength 589 nm has almost no effect. The spectral efficiency of the regenerative effect is identical to the probability that light quanta will be absorbed by the thermostable secondary pigment. The results suggest that the sensitivity of the UV receptor is determined solely by the absorption of light quanta, without any chemical resynthesis of visual pigment. As in cuttle-fish, a receptor potential is elicited only when light is absorbed by the primary pigment. Light absorption by the secondary pigment is ineffective.

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Mit Unterstützung durch die DFG, SFB Bionach.

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Mit Unterstützung durch die jugoslawischen SBK- und SFNR-Fonds.     

Über melaninbildende Stämme von Pseudomonas aeruginosa

Zusammenfassung Der Tyrosinstoffwechsel von 12 auf Peptonagar Melanin bildenden und 15 melaninfreien Kontrollstämmen der Species Pseudomonas aeruginosa wird untersucht. Es wird ein tyrosinfreies Ammoniumgluconat-Medium angegeben, auf dem bei gutem Wachstum aller Stämme keine Melaninbildung erfolgt. Ein Zusatz von Tyrosin oder seinen Precursoren gestattet eine deutliche Unterscheidung der Melaninbildner von den melaninfreien Stämmen innerhalb 16 Std. Die Melaninbildung wird durch Tyrosinasehemmer wie KCN, Na₂S, Natriumdiäthyldithiocarbaminat usw. nicht beeinflußt. DOPA und DOPA chrom ließen sich in den Kulturextrakten nicht nachweisen. Es besteht keine Identität zwischen dem braunen Pigment und authentischem DOPA-Melanin. Sämtliche Melaninbildner zeigen eine Akkumulation von Homogentisinsäure mit nachfolgender Entwicklung eines anfangs roten, später braunen Pigmentes, während die melaninfreien Stämme keine Homogentisinsäure in nachweisbaren Mengen anhäufen. Unterbindet man die Melaninproduktion durch Anzüchtung der Keime auf tyrosinfreien Medien, so kommt es namentlich bei Zusatz von l-Tryptophan zu der für Pseudomonas aeruginosa typischen Anreicherung des Geruchsstoffes o-Aminoacetophenon und 4-Methylchinazolin. Die Hemmung des Chinazolinweges bei den Melaninbildnern wird mit der Tryptophanpyrrolase-Hemmung durch Hydrochinon verglichen.Die melaninbildenden Stämme der Species Pseudomonas aeruginosa sind nicht als tyrosinasehaltige Varianten aufzufassen, sondern als Verlustmutanten mit dem genetisch bedingten Defekt der Homogentisicase, ein Analogiefall zur Alkaptonurie.

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Melanin-forming strains of pseudomonas aeruginosa

Summary Studies are performed on tyrosine metabolism of 12 melaninforming and 15 melanin-free strains of Pseudomonas aeruginosa grown on pepton agar. Melanin production does not occur in tyrosineless ammoniumgluconate medium. Addition of tyrosine or its precursors to this basis-medium allowed to distinguish between the melanin-forming and melanin-free strains within 16 hours. Inhibitors of tyrosinase such as KCN, Na₂S, sodium-diethyl-dithiocarbaminate etc. are proved to be without influence on the pigment production. DOPA and DOPA-chrome are not present in the culture extracts. There is no identity between the isolated brown pigment and authentic DOPA-melanin. All melanin-forming strains are found to be remarkable by accumulating homogentisic acid followed by developing a red, later brown pigment, whereas the melanin-free strains do not concentrate homogentisic acid in detectable amounts. Preventing the melanin formation by growth on the tyrosineless basis-medium with addition of l-tryptophan the quinazoline pathway is employed again, which had been found inhibited during simultaneously occuring production of the brown pigment. Probably this effect may be caused by accumulated homogentisic acid similar to the inhibition of tryptophan-pyrrolase by hydroquinone.The melanin-forming strains of the species Pseudomonas aeruginosa are not regarded as variants containing a tyrosinase but as mutants with a genetic defect of homogentisicase in analogy to the alcaptonuria in metabolic diseases of men.

     

Über die Farbstoffbildung durchAzotobacter chroococcum

Zusammenfassung Der schwarzbraune Farbstoff vonA. chroococcum wird bei gehemmter Substratatmung gebildet. Das wurde durch stark gedrosselte Phosphorversorgung bei im übrigen optimaler Ernährung und betont guter Versorgung mit Kalium, Eisen und Kupfer erreicht.Da nur bei neutraler bis alkalischer Reaktion Farbstoff gebildet wird, was es notwendig, das Nährsubstrat ausreichend zu puffern. Es erhielt deshalb einen Zusatz von Calciumcarbonat. Geschah das nicht, dann bildeteA. chroococcum bei Phosphormangel Zuckeroxydationsprodukte, wahrscheinlich Gluconsäure neben möglicherweise noch anderen Säuren, wobei der pH-Wert bis 4 oder etwas tiefer absank. Glucuronsäure entstand in sehr geringen Mengen unter allen geprüften Ernährungsbedingungen. A. chroococcum war katalatisch aktiver alsA. agilis, ganz besonders bei Phosphormangel, vermutlich deshalb, weilA. chroococcum unter diesen Bedingungen vornehmlich über das Flavinsystem atmete und dabei auch mehr Wasserstoffperoxyd bildete.Der mit viel Phosphat ernährte Bakterientyp vonA. chroococcum reagierte auf verschiedene Atmungshemmstoffe empfindlicher als der Typ aus phosphatarmer Nährlösung. Auch das spricht dafür, daß der schwächer atmende, farbstoffbildende Typ über das Flavinsystem atmete und nicht über das Cytochromsystem mit den zugehörigen Phosphorylierungen, was für den phosphorreich ernährten Stoffwechseltyp zutrifft.

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On pigment production byAzotobacter chroococcum I. Culture conditions favouring pigment production

Summary The brownish black pigment ofA. chroococcum is produced during restricted respiration of the substrate. This condition was obtained by lowering drastically the phosphorus supply while the nutrition for the rest was optimal and potassium, iron, and copper were available in sufficient concentrations.Since pigment is produced only with neutral or alcaline reaction it was necessary to buffer the culture medium sufficiently. For this purpose calcium carbonate was added. Without buffering A. chroococcum when lacking phosphorus formed products of sugar oxidation, probably gluconic acid and possibly other acids, too, while the pH-value declined to 4 or somewhat below. Glucuronic acid was produced in very small quantities at any nutritional condition checked. A. chroococcum was more active in catalase thanA. agilis, especially with lack of phosphorus. This is supposed to be due to the fact that under such conditions the flavine system producing higher quantities of hydrogen peroxide is primarily active in respiration ofA. chroococcum.The type ofA. chroococcum grown in a medium rich in phosphorus was more susceptible to various inhibitors of respiration than was the other type grown in a medium lacking phosphorus. This also points to the fact that the more weakly respiring and pigment-producing type acts by the flavine system and not by the cytochrome system using phosphorylations as does the metabolic type developing with abundant supply of phosphorus.

     

Serum pigmentation in Cyclopterus lumpus L

Female lumpsuckers, Cyclopterus lumpus L., have blue-green blood serum and subcutaneous gelatinous tissue; the male's are red/magenta in colour. The female serum contains a chromoprotein with biliverdin as the prosthetic group; the male serum contains the same biliverdin pigment but this is normally masked by a red pigment, probably phycoerythrin. The female serum also contains the red pigment but at a much lower concentration than in the male. These bile pigments are probably formed by the breakdown of haem in the liver. Lumpsucker gall bladders are relatively small and do not enlarge during starvation. Storage of bile pigments in the serum and subcutaneous jelly may have arisen in response to the problems of regular long-term starvation. The pigments now appear to have an additional sexual signalling function.     

Über die Bildung der Augenpigmentgranula beiDrosophila v undcn nach Verfütterung von Ommochromvorstufen

Zusammenfassung Bei denDrosophila-Mutantenv undcn, die weder Ommochrom noch leere Pigmentgranula aufweisen, läßt sich durch Verfüttern von Kynurenin, bzw. 3-Hydroxy-kynurenin die Bildung von Pigmentgranula induzieren, die von den Granula des Wildtyps nicht zu unterscheiden sind. Ihr größter Durchmesser beträgt ca. 0,4 , sie sind von einer Membran umgeben und ihre Wachstumsgeschwindigkeit ist identisch.Messung der heranwachsenden Granula in proximalen und distalen Bereichen der Ommatidien erbrachten einen signifikanten Größenunterschied; dieser ist bereits 48 Std nach der Verpuppung erkennbar.

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On the formation of eye pigment granules after feeding ommochrome precursors toDrosophila v andcn

Summary In the mutantsv andcn ofDrosophila, which contain neither ommochrome pigment nor empty pigment granules, feeding of kynurenine or 3-hydroxy-kynurenine causes the formation of pigment granules which cannot be distinguished from wild type granules. Their larger diameter is about 0.4 , they are surrounded by a membrane, and their growth rate is identical.Measurement of growing pigment granules in proximal and more distal regions of the ommatidia has revealed a significant difference in size which can be recognized as early as 48 hours after pupation.

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Wir danken der Deutschen Forschungsgemeinschaft für die finanzielle Unterstützung, Herrn Dr. F. G. Barth, Herrn Prof. H. Altner und seinen Mitarbeitern, sowie Frl. H. Tscharntke für Einweisung und Hilfe in der EM-Technik, und Herrn Dr. F. Schwabl für seinen Rat bei der Auswertung der Messungen.     

Ultrastructural and functional study of the liver pigment cells from Rana esculenta L.

Summary A study of the liver pigment cells of Rana esculenta L. has been performed on both liver in toto and cells in culture. Ultrastructural and cytochemical analyses showed a close relationship between this visceral pigment cell system and the cells of hepatic macrophage lineage. Like the latter, the liver pigment cells present phagocytic activity, in the sinusoids and in vitro, and give a positive response to tests for peroxidase and lipase. The liver pigment cells are isolated, together with the Kupffer cells, from the sinusoidal cell fraction of the liver. In culture, they maintain their melanogenetic ability, demonstrated by the presence of dopaoxidase activity in the soluble, membranous, and melanosome fractions. Analysis of the cultures showed that as culture time increased, so did melanosome dopaoxidase activity, the number of pigmented fields, and the level of pigmentation of the cells. The values of dopaoxidase activity of the pigment cells in culture show the same seasonal oscillations as the system in toto, indicating that the cells maintain an internal clock, at least in the first 72 h of culture. There is evidence that the pigment cells are macrophages which can express a melanogenetic function. Our results and other experimental data provide a basis for hypothesizing that the pigment cells in Rana esculenta L. liver may derive from, or have a common origin with, the Kupffer cells.     

Carotine und Carotinoidsynthese in Rhizobium lupini-Mutanten

Zusammenfassung Die Pigmentzusammensetzung einiger Mutanten von Rhizobium lupini wurde chromatographisch und spektralphotometrisch bestimmt. Aus dem Fehlen, Neuauftreten und der Kombination verschiedener Pigmente wurde ein Schema für den möglichen Weg der Biosynthese der Carotinoide aufgestellt.

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Summary The pigment composition of several mutants of Rhizobium lupini was determined by chromatography and by spectralphotometry. Using the factors loss or new appearance of pigments and combination of different pigments a scheme was developed for the possible way of the carotenogenesis in non-photosynthetic bacteria.

     

The Existence of Chlorophyll c in the Chl b-Containing,Light-Harvesting Complex of the Green Alga Mantoniella squamata (Prasinophyceae)

The prasinophycean alga Mantoniella contains, in addition to Chl a and b, at least a third green pigment which is functionally active in the light-harvesting antenna. This third Chl was isolated in order to elucidate its chemical structure. The absorption and fluorescence spectra were measured not only from the purified pigment but also from its pheophytin and its methylpheophorbide. The spectra were compared with those of authentic Chl c-1 and c-2, which were isolated from the diatom Nitzschia sp. and with Mg-DVPP (purified from Rhodobacter). The results show that the pigment from Mantoniella compares best with Chl c-1. In order to clarify the spectral data, Chl c-1 and c-2, Mg-DVPP, and the pigment from Mantoniella were subjected to a chromatographic system that is able to separate these porphyrins. The chromatographic analysis clearly shows that the pigment from Mantoniella co-migrates with Chl c-1 and not with the bacterial pigment. Mantoniella is the first organism which has been demonstrated to contain Chl a, b, and authentic c.     

Hell-und Dunkeladaptation der Augen vonPieris brassicae L. (Lepidoptera)

Summary The compound eyes ofPieris brassicae L. have a tiered retina. During light and dark adaptation, ultrastructural changes have been observed throughout the length of the ommatidia in the latero-ventral region of the eyes. These changes have been quantitated by mapping at distinct levels of the ommatidia, and plotted as histograms. Both in visual cells and secondary pigment cells and at the attachment region between crystalline cone and rhabdome such ultrastructural changes have been found to be correlated to the state of adaptation.Distal and proximal photoreceptor cells show different adaptation mechanisms. Whereas the distal cells show a clear pupil mechanism in their distal parts, there is only very little horizontal movement of pigment granules in the proximal cells. In the proximal cells, multivesicular bodies (MVB) are always abundant, while in the distal cells their number is small and increases slightly during light adaptation. In the proximal cells light adaptation causes pigment granules, located in the distal process, to move proximally. Increasing the light intensity from 160 to 1600 W/cm² results in more intense migration of pigments.In the secondary pigment cells, a slight but significant distal movement of pigment granules is observed at high light intensity. If continued this condition causes the granules to aggregate in the vicinity of the apical cell membrane, and to move up to the distal inflated extensions of the distal processes formed by these cells. In dark adapted eyes, these processes are nearly devoid of pigment and the pigment granules beneath the apical membrane disperse. In addition to these structural changes, there is a tendency for retinal movements at the attachment from crystalline cone to rhabdome. — The various adaptation mechanisms are not equally well developed in different regions of the compound eye.

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Hell-und Dunkeladaptation der Augen vonPieris brassicae L. (Lepidoptera)

Zusammenfassung Die Retina vonPieris brassicae L. ist mehrreihig. Erstmals wurden feinstrukturelle Veränderungen während der Hell und Dunkeladaptation über die gesamte Länge der Ommatidien des latero-ventralen Augenbereichs anhand von Kartierungen in vergleichbaren Höhen der Ommatidien untersucht und in Histogrammen wiedergegeben. — Sowohl in den Sehzellen als auch Nebenpigmentzellen und am Übergang von Kristallkegel zum Rhabdom wurden feinstrukturelle Veränderungen in Korrelation mit der Adaptation gefunden.Die Adaptation erfolgt bei distalen und proximalen Sehzellen jeweils auf andere Art. Während die distalen Sehzellen in ihrem distalsten Bereich sehr gut die Pupillenreaktion zeigen, adaptieren die proximalen Sehzellen nur geringfügig mit horizontaler Pigmentwanderung. Auch die Anzahl der multivesikulären Körper (MVB), die in den proximalen Sehzellen immer groß ist, steigt bei Helladaptation (HA) nur in den distalen Sehzellen etwas an. In den proximalen Sehzellen wandern die Pigmentgranula bei HA geringfügig aus dem distalen Fortsatz dieser Sehzellen proximalwärts. Intensitätssteigerung auf das 10fache (von 160 auf 1600W/cm²) bewirkt eine Verstärkung der genannten Pigmentwanderungs-Reaktionen in den Sehzellen.Die Granula der Nebenpigmentzellen wandern bei HA mit starker Intensität etwas distalwärts. — Bei starker langer HA häufen sich diese Granula unter der apikalen Membran dieser Nebenpigmentzellen und wandern bis in die distalen kleinen Erweiterungen der distalen Fortsätze dieser Zellen. Bei Dunkeladaptation (DA) sind diese Fortsätze nahezu frei von Pigment; unter der apikalen Zellmembran verteilen sich die Pigmente locker. Außerdem besteht am Übergang von Kristallkegel zu Rhabdom die Tendenz zur Retinomotorik. — In den verschiedenen Augenbereichen erfolgen die genannten Adaptationsreaktionen unterschiedlich gut.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft und der Stiftung Volkswagenwerk

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Herrn Prof. Dr. Kurt Hamdorf (Bochum) danken wir für kritische Diskussion und Fräulein Althaus für die graphischen Darstellungen     

Der UV-Sehfarbstoff der Insekten: Photochemie in vitro und in vivo

Zusammenfassung Die Untersuchungen an Extrakten des UV-Sehfarbstoffes aus den Frontalaugen von Ascalaphus macaronius ergeben ein thermostabiles Retinal-Farbstoffsystem, ähnlich dem der Cephalopoden. Die Folgefarbstoffe B und C stehen — wie die analogen Metarhodopsine — in einem pH-abhängigen Gleichgewicht, dessen pK-Wert mit 9,2 weit im alkalischen Bereich liegt. Da C in mikrophotometrischen Untersuchungen nicht in meßbaren Konzentrationen auftritt, wird vermutet, daß dieses Intermediärprodukt für den Sehvorgang keine Rolle spielt. Durch mikrophotometrische Messungen wird das in Lösung gefundene Folgeprodukt B auch in der nativen Membran nachgewiesen. Es wird die Zeitfunktion der Photoiso- und -reisomerisierung der Farbstoffe in der nativen Membran bestimmt. Da das Folgeprodukt B auch im lebenden Rezeptor durch Licht der Wellenlängen 440–600 nm vollständig in den Ausgangsfarbstoff reisomerisiert wird, und weiterhin die photometrischen Messungen keinerlei Hinweis auf eine chemische Resynthese ergeben, wird gefordert, daß die Empfindlichkeit des UV-Rezeptors ausschließlich durch Lichtenergie, d.h. ohne jede Stoffwechselleistung, aufrechterhalten wird.

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The ultraviolet visual pigment: photochemistry in vitro and in vivo

Summary The u.v.-visual pigment, isolated from the frontal eyes of Ascalaphus macaronius, is a thermostable retinal-system like that of the cephalopoda. Products B and C are in a pH-dependant steady-state similar to the metarhodopsins of the cephalopods. The pK is 9.2. Since we could not detect any secondary pigment C in the living receptormembrane, we suggest that this product is not involved in the visual process. Microphotometric measurements showed that photoproduct B formed by u.v.-irradiation is identical to the product found in solution. The time-course of the photoreactions AB and BA is determined in the living receptor. As Bis completely reconverted to A in the native membrane by light of longer wavelengths (440–570 nm), and furthermore since there was no evidence of a chemical regeneration (BA) in the dark, it is postulated that the sensitivity of the u.v.-receptor is regulated only by the photoreactions.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft und

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der jugoslawischen SBK- und SFNR-Fonds.     

Pigment formation in the dermatophytes

Avstract The moist mycelium ofT. tonsurans was extracted with 3 % w/v sodium hydroxide to yield a purple to violet solution which was passed through a cation-exchange resin column, evaporated partially, dialyzed and lyophilized. The lyophilized powder was extracted using absolute ethanol, acetone and chloroform (Process A) and separately by defatting with petroleum ether and n-hexane followed by chloroform-methanol 2:1 (Process B).Separation was achieved for the extract of Process B on thin layer chromatography using Silica Gel G and butanol-ethanol-water as the solvent system. Ultra-violet and visible spectrophotometric absorption data are reported for the lyophilized extract ofT. tonsurans, hydrolyzates of the lyophilized extract, and for sodium hydroxide extracts ofT. megnini, T. mentagrophytes, T. rubrum, T. tonsurans andT. violaceum. The spectra were similar in all cases.A review of pigment substance in dermatophytes is made, which together with the experimental data secured withT. tonsurans and previous experimentation, suggest the possible effects of drying procedures, contusion, solvents, acidic additives and method of extraction on the removal of pigment from the mycelium of dermatophytes. It is suggested that all the above conditions influence the substances ultimately extracted and that some alteration of a basic pigment association in the organism occurs to release pigment fragments or fractions of varying complexity. Oxidation and polymerization may influence the end result. It is possible that the mechanism presented can account for the number of pigment substances reportedly occurring in the dermatophytes and that a similar pigment structure or complex exists in other Trichophyton species.Grateful thanks are extended to the Medical Research Council of Canada for financial support.     

Crustaceans and rotifers in the predatory feeding of Utricularia

The contents of bladders in the predatory plant Utricularia from three waterbodies were studied. The composition and number of prey depended on the development of zooplankton and phytophilous fauna in the environment. The probability of getting the prey into the bladder was determined by the specificity of the prey’s behavior and size. The most numerous prey were predatory Copepoda and nonpredatory Cladocera, which use the bladderwort as a substrate. The shares of other cladocerans in the bladders were inconsiderable when there were high densities of these species in the waterbody. No negative impact of the bladderwort on the rotifer abundance was revealed.     

Predation by the tropical plant Utricularia foliosa

1. We examined the prey captured by individual plants of the tropical carnivorous plant Utricularia foliosa, located in different areas along a creek in the Colombian Amazon and the zooplankton and macroinvertebrate communities associated with the plants. The aims were: (i) to determine whether bladders of different sizes within each plant catch different numbers of prey or exploit different size ranges and types of prey, (ii) if the quantity and composition of prey captured varies temporally and/or spatially and (iii) if the plant has evolved effective mechanisms of attracting prey. 2. Utricularia foliosa captured the most abundant species of macroinvertebrates associated with the plant. Larger bladders captured more, larger and more diverse prey. However, benefits of the extra prey caught by large bladders were not offset by the greater cost of producing bladders larger than approximately 1650 μm. 3. The number of prey captured was higher in those plants with more carbohydrates per bladder and with a higher ratio of antenna size/bladder length. The antennae enhance capture success by offering the prey a favourable substratum that exploits their natural locomotor and feeding behaviour. However, although carbohydrates may lure prey, carbohydrate production was not a strategy of the plant to enhance the capture of prey, because the amount of carbohydrates in the bladder was related to the abundance of periphyton.     

The utilization of paramecia by the carnivorous plant Utricularia gibba

Summary A method has been devised to ensure capture of large numbers of live paramecia within a short period of time under controlled conditions by the bladders of Utricularia gibba. The method permits a direct evaluation of the role of entrapped animals in the nutrition of this carnivorous plant. Paramecia captured by the bladders of plants growing in a near optimal inorganic medium do not cause an increase in number or length of internodes. In contrast, feeding paramecia to plants grown in a poorly balanced or incomplete medium does result in an increase in both number and length of internodes produced. Feeding paramecia to Utricularia also results in an increase in number of bladders.This study was supported in part by an Undergraduate Research Participant stipend from Public Health Service, grant number 2-TIHE 5 303-09, to the first author and in part by Agricultural Research Service, U.S. Department of Agriculture, Grant No. 12-14-100-7981 (34) to the second author, administered by Crops Research Division, Beltsville, Maryland.     

Unusual development of light-reflecting pigment cells in intact and regenerating tail in the periodic albino mutant of Xenopus laevis

Unusual light-reflecting pigment cells, “white pigment cells”, specifically appear in the periodic albino mutant (a ^p /a ^p ) of Xenopus laevis and localize in the same place where melanophores normally differentiate in the wild-type. The mechanism responsible for the development of unusual pigment cells is unclear. In this study, white pigment cells in the periodic albino were compared with melanophores in the wild-type, using a cell culture system and a tail-regenerating system. Observations of both intact and cultured cells demonstrate that white pigment cells are unique in (1) showing characteristics of melanophore precursors at various stages of development, (2) accumulating reflecting platelets characteristic of iridophores, and (3) exhibiting pigment dispersion in response to α-melanocyte stimulating hormone (α-MSH) in the same way that melanophores do. When a tadpole tail is amputated, a functionally competent new tail is regenerated. White pigment cells appear in the mutant regenerating tail, whereas melanophores differentiate in the wild-type regenerating tail. White pigment cells in the mutant regenerating tail are essentially similar to melanophores in the wild-type regenerating tail with respect to their localization, number, and response to α-MSH. In addition to white pigment cells, iridophores which are never present in the intact tadpole tail appear specifically in the somites near the amputation level in the mutant regenerating tail. Iridophores are distinct from white pigment cells in size, shape, blue light-induced fluorescence, and response to α-MSH. These findings strongly suggest that white pigment cells in the mutant arise from melanophore precursors and accumulate reflecting platelets characteristic of iridophores.