Cytomorphogenetic- and anti-microtubule action of the antibiotic gougerotin inMicrasterias denticulata Bréb.

Summary Differentiating cells ofMicrasterias denticulata have been treated with aqueous solutions of the antibiotic gougerotin. Strong and characteristic cytomorphogenetic aberrations, resembling those of the anuclear type of development could be observed. It has been speculated that the aberrant growth of the growing half cell is the result of inhibition of protein synthesis by gougerotin.In addition to the morphogenetic influence, nuclear migration has been strongly inhibited by the drug. Therefore, it might be suggested that gougerotin is an active anti-microtubule agent.     

Hexagonally ordered “rosettes” of particles in the plasma membrane ofMicrasterias denticulata Bréb. and their significance for microfibril formation and orientation

Summary Cells ofMicrasterias denticulata Bréb. at the stage of secondary wall formation have been studied by freeze-etching. It was found that the plasma membrane exhibits oval areas in which arrays of membrane particles occur. These particles form rosettes which are arranged in a hexagonally ordered lattice with a center to center spacing of 25 nm. Nearly the same periodicities can be found between microfibrils. It is concluded that the rosettes probably together with the thickened area of the plasma membrane below them represent the apparatus for the production and orientation of microfibrils. The hypothesis suggesting the incorporation of membrane templates functional in microfibril formation, originally advanced byKiermayer andDobberstein (1973) has received further support.     

Elektronenmikroskopische Untersuchungen zum Problem der Cytomorphogenese vonMicrasterias denticulata Bréb

Zusammenfassung Wachsende, sich differenzierende Zellen vonMicrasterias denticulata Bréb. wurden 10 bis 15 Minuten mit Glutaraldehyd fixiert, mit OsO₄ nachfixiert und elektronenmikroskopisch untersucht.Das Protoplasma wachsender Halbzellen enthält zahlreiche Organellen und Vesikel, es konnte aber kein Anordnungsmuster dieser cytoplasmatischen Gebilde gefunden werden, das zu den morphogenetischen Prozessen, welche zur charakteristischen Form der Micrasterias-Zellen führen, eine Beziehung gezeigt hätte.Zwei verschiedene Typen von Vesikeln werden von den Zisternen der Dictyosomen abgeschnürt: large vesicles (0,3–1,0, LV) mit Inhalt von geringer Elektronendichte, und dark vesicles (800–2500 Å, DV) von starkem Kontrast. Wir nehmen an, daß L-Vesikel möglicherweise Schleim enthalten, der durch die Poren der Zellwand sezerniert wird (Abb. 15–17), während sich in den D-Vesikeln Zellwandmaterial befindet. Neben diesen zwei Typen von Golgi-Vesikeln wurden im Cytoplasma coated vesicles (CV) und rod-containing vesicles (SV) gefunden, die erstgenannten oft während der Verschmelzung mit dem Plasmalemma (Abb. 3).Dictyosomen und Zisternen des rauhen ER sind die hervorstechenden Bestandteile des Cytoplasmas der wachsenden Halbzelle, während Mitochondrien und Microbodies nur in relativ kleiner Zahl vorhanden sind. In sehr jungen Entwicklungsstadien ballen sich dieDictyosomen, zusammen mit ER, Mitochondrien und Mikrotubuli, um den Posttelophase-Kern, was auf eine Plasmaschichtung in diesen frühen Entwicklungsstadien schließen läßt. In älteren Stadien, wenn der Nukleus tiefer in die wachsende Halbzelle wandert, sind die Organellen jedoch über das gesamte Protoplasma verteilt.Die Dictyosomen, die ausgesprochen polaren Bau aufweisen, d. h. breite Zisternen an der einen Seite (proximaler Pol) und enge an der anderen (distaler Pol), sind nach unseren Beobachtungen stets an ihrem proximalen Pol einer Zisterne des ER angelagert (Abb. 9 und 10–12). Kleine Vesikel wurden zwischen dieser ER-Zisterne und dem Dictyosom gefunden (Abb. 10 und 11,VX). Sie spielen wahrscheinlich eine Rolle bei der Bildung neuer Golgi-Zisternen. Während L- und D-Vesikel von Zisternen ein und desselben Dictyosoms abgeschnürt werden (Abb. 11), konnte bisher noch keine Aufnahme gemacht werden, die die Entstehung der coated vesicles klären würde. Knospung der Membran von D-Vesikeln stellt vielleicht ein Stadium der Bildung von coated vesicles dar (Abb. 19).In einigen wenigen Fällen fanden sich Dictyosomen, die entlang einer Bruchstelle durch die Mitte der Golgi-Zisternen in zwei Hälften zerfielen (Abb. 10 und 11). Die Aufspaltung der Zisternen beginnt am proximalen Pol und schreitet gegen den distalen Pol fort. Diese Erscheinung wird als Teilungsstadium eines Dictyosoms gedeutet.In sehr jungen Entwicklungsstadien wurde ein Stapel paralleler ER-Zisternen (Ergastoplasma) in der Nähe des Kerns gefunden (Abb. 20); in späteren Stadien herrschen dagegen einzelne Zisternen vor, die das gesamte Cytoplasma der Halbzelle durchziehen. Die Differenzierung des ER zum Ergastoplasma zeigt vermutlich die hohe Stoffwechselaktivität dieser frühen postmitotischen Entwicklungsstadien an.In alten Halbzellen ist eine ER-Zisterne der Chloroplastenhüllmembran angelagert und bildet eine Periplastidärzisterne (Abb. 21). Dictyosomen nähern sich dieser ER-Zisterne auf sehr engem Abstand.Vier deutlich verschiedene Systeme von Mikrotubuli konnten in wachsenden Zellen nachgewiesen werden und wurden in einer früheren Arbeit ausführlich beschrieben. Keines von ihnen zeigt jedoch eine Lagebeziehung zur Symmetrie oder zur Form der wachsenden Halbzelle. Deshalb und in Übereinstimmung mit früheren osmotischen Untersuchungen vermuten wir, daß die Plasmamembran selbst in ihrer Molekularstruktur ein spezifisches Muster enthält, das die Ablagerung von Zellwandmaterial kontrolliert. Obwohl gegenwärtig noch keine weiteren Einzelheiten und keine experimentellen Beweise für ein solches Muster zur Verfügung stehen, nehmen wir an, daß möglicherweise die Vesikel-Membranen in einer Art intrazellulärer Membran-Erkennungsreaktion (membran-recognition) besondere Affinität zu lokalen Bezirken der Plasma-Membran aufweisen und ihren Inhalt nur an diesen Stellen an die wachsende Wand abgeben. Ein derartiger Mechanismus könnte trotz Zufallsverteilung der Organellen und Vesikel und sehr lebhafter Plasmaströmung zum Wachstum der Primärwand nach vorgegebenem Muster führen.

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Electron microscopic studies on the problem of cytomorphogenesis inMicrasterias denticulata BrébI. General survey

Summary Growing and differentiating cells ofMicrasterias denticulata Bréb., fixed with glutaraldehyde for 10–15 minutes and postfixed with OsO₄, were studied under the electron microscope. The protoplasm of growing half cells contains numerous organelles and vesicles, but no patterned arrangement of these cytoplasmic components in relation to the morphogenetic process leading to the characteristic shape ofMicrasteriascells could be observed.Two different kinds of vesicles are pinched off by cisternae of the dictyosomes,i.e. large vesicles (0.3–1.0, LV) with a content of low electron density and dark vesicles (800–2500 Å, DV) with a high contrast. It is assumed that L-vesicles possibly contain slime which is secreted through the pores of the secondary wall (Figs. 15–17), while D-vesicles contain cell wall material. Beside these two kinds of Golgi-vesicles, coated vesicles (CV) and rod-containing vesicles (SV) were found in the cytoplasm, the former often in a stage of fusion with the plasmalemma (Fig. 3).Dictyosomes and cisternae of the rough ER are the most prominent cytoplasmic components of the growing half cell, while mitochondria and microbodies are present only in relatively small numbers. In very young developmental stages dictyosomes together with ER, mitochondria, and microtubules are clustered around the post-telophase nucleus, indicating a plasmatic stratification in these early developmental stages. However, in older stages when the nucleus migrates deeper into the growing half cell the organelles are distributed over the entire protoplasm.Dictyosomes, showing a pronounced polar configuration,i.e. wide cisternae on one side (proximal pole) and narrow one on the other (distal pole), were found to be constantly associated at their proximal pole with a cisterna of the ER (Figs. 9, 10–12). Little vesicles were found between this ER-cisterna and the dictyosome (Figs. 10 and 11,VX), possibly playing a role in generating new Golgi-cisternae. While L- and D-vesicles are undoubtedly pinched off by cisterna of one and the same dictyosome (Fig. 11), no picture as yet could be obtained clarifying the origin of the coated vesicles. Budding of the membrane of D-vesicles may perhaps indicate a stage of formation of coated vesicles (Fig. 19).In a few cases dictyosomes were found to be split into two halfs by a median break of the Golgi-cisternae (Figs. 10 and 11). The median splitting of the cisternae starts at the proximal pole and proceeds toward the distal pole. This phenomenon is interpreted as a divisionstage of a dictyosome.In very young stages a stack of parallel ER-cisternae (ergastoplasm) was found in the vicinity of the nucleus (Fig. 20) while in later stages single cisternae, penetrating the whole cytoplasm of the half cell, dominate. The ergastoplasmic differentiation of the ER presumably indicates the high metabolic activity of these early postmitotic developmental stages. In non-growing half cells one ER-cisterna approaches the chloroplast-membrane thus forming a periplastidial cisterna (Fig. 21). Dictyosomes approach very closely this ER cisterna (Fig. 23).Four distinct systems of microtubules could be found in growing cells (described in detail in a previous paper) but none of them exhibit a positional relationship to the symmetry and pattern of the growing half cell. For this reason and in agreement with previous osmotic studies it is speculated that the plasma-membrane itself maintains a specific pattern in its molecular structure that controls the deposition of wall-material. Although no further information or experimental support is available at present for such a pattern it is thought that perhaps vesicle-membranes in a manner of intracellular membrane recognition show special affinities to local areas of the plasma-membrane and discharge their content for the growing wall only at these loci. Such a mechanism could lead to a patterned growth of the primary wall in spite of a random distribution of organelles and vesicles and a very vigorous protoplasmic streaming.

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This work was supported by a National Science Foundation Senior Foreign Scientist Fellowship to Dr. Oswald Kiermayer, and by funds of Training Grant 5-M 1-GM-707-06 to Dr. Keith R. Porter.

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I am most grateful to Drs.Keith R.Porter andPeter K.Hepler (Harvard University) for numerous discussions and guidance in this investigation and also Mrs. Pamela Pettengill for her technical help.     

Elektronenmikroskopische Untersuchungen zum Problem der Cytomorphogenese vonMicrasterias denticulata Bréb.

Zusammenfassung Die Wirkung einer Blockade der Proteinsynthese durch Cycloheximid wurde an sich differenzierenden Zellen vonMicrasterias denticulata Bréb. licht- und elektronenmikroskopisch sowie mikrokinematographisch untersucht. Es wurde der Befund vonTippit andPickett-Heaps (1974) bestätigt, daßMicrasterias-Zellen unter dem Einfluß von Cycloheximid eine abnorme Zellentwicklung zeigen, die sich in einer Vereinfachung des Zellmusters und einem blasigen Anschwellen der Lappen äußert (anucleate type of development).Die Primärwand Cycloheximid-behandelter Zellen weist eine markante Änderung ihrer Ultrastruktur auf. Und zwar finden sich diskrete Partikel, bei denen es sich mit großer Wahrscheinlichkeit um die Inhalte von D-Vesikel (Kiermayer 1970) handelt, in einer eigenen zusätzlichen Schicht an die homogene Primärwandschicht angelagert. Es wird angenommen, daß durch die Hemmung der Proteinsynthese während der Zellentwicklung D-Vesikelinhalte ihre Fähigkeit verlieren, sich in die wachsende Primärwand einzulagern. Ein möglicher Zusammenhang dieses Phänomens mit der Entstehung der typischen Zellmißildungen wird diskutiert.Die Bildung einer Sekundärwand wird durch Cycloheximid verhindert.

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Formation and ultrastructure of the primary wall ofMicrasterias denticulata Bréb. under the influence of cycloheximide

Summary The effect of a blockade of protein synthesis by cycloheximide on differentiating cells ofMicrasterias denticulata Bréb. has been studied by light- and electronmicroscopy and microcinematography. The result ofTippit andPickett-Heaps (1974) thatMicrasterias cells, treated with cycloheximide show an abnormal cell development, e.g., reduction of the cell pattern and a bladderlike swelling of the lobes (anucleate type of development) could be supported.The primary wall of cycloheximide treated cells shows a striking change of its ultrastructure. Many discrete particles very probably representing the content of D-vesicles (Kiermayer 1970) form a separate additional inner layer near the outer homogenous layer of the primary wall. It is suggested that during an inhibition of protein synthesis the content of D-vesicles looses its ability to be incorporated into the growing cell wall. A possible connection of this phenomenon with the typical malformation of the cell is discussed.The formation of a secondary wall is prevented by cycloheximide.

Die Untersuchungen wurden vom Fonds zur Förderung der wissenschaftlichen Forschung (Projekt Nr. 2783, 3660) unterstützt; Frau Ing.Doris Pinegger danken wir für die technische Hilfe.     

Untersuchungen über die Morphogenese und Zellwandbildung beiMicrasterias denticulata Bréb

Ohne ZusammenfassungMeinem verehrten Lehrer, Herrn Prof. Dr. K. Höfler, nachträglich zum 70. Geburtstag in Dankbarkeit gewidmet.Der Deutschen Forschungsgemeinschaft danke ich für die Unterstützung der Untersuchungen. Herrn cand. rer. nat. H. Lehmann für seine tatkräftige Hilfe.     

Elektronenmikroskopischer Nachweis spezieller cytoplasmatischer Vesikel bei Micrasterias denticulata Bréb.

Summary Electronmicroscopic studies of growing and non-growing cells of Micrasterias denticulata Bréb., fixed with glutaraldehyde-OsO₄, showed a special kind of cytoplasmic vesicle which has so far not been found in other cells. These particles (1000–1200 Å in diameter) are characterized, by an unusual, multilayered membrane and a rod-like content of high electronoptic density. The vesicles are found to be accumulated in the vicinity of the nucleus and in a positional relationship to the nuclear pores. Although no evidence could be found either for a direct passage of the vesicles through the pores or for a blebbing-process from the nuclear membrane, the rod-containing vesicles could be functional in the process of nuclearcytoplasmic exchange.

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Herrn Prof. Dr. H. Drawert zum 60. Geburtstag gewidmet.

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Diese Arbeit wurde zum Teil durch ein National Science, Foundation Senior Foreign Scientist Fellowship an Dr. Oswald Kiermayer und durch einen Training Grant 5-T1-GM-707-06 an Dr. Keith R. Porter, Harvard University, unterstützt.     

Beeinflussung der postmitotischen Kernmigration vonMicrasterias denticulata Bréb. durch das Herbizid Trifluralin

Zusammenfassung Zellen vonMicrasterias denticulata Bréb. wurden wÄhrend der Phase des postmitotischen Wachstums mit Trifluralin behandelt. In einem Konzentrationsbereich von 10^–2 bis 10^–5% zeigte sich ein starker Einflu\ auf die Kernmigration, wodurch der Zellkern eine anormale Position innerhalb der Zelle einnahm. Daneben war auch die Migration des Chloroplasten stark gehemmt. Ein Effekt auf die Cytomorphogenese, d. h. das Wachstum und die Musterbildung der PrimÄrwand konnte nicht beobachtet werden. Es wird angenommen, da\ Trifluralin, so wie Colchizin, Vinblastin, IPC und CIPC auf das den Posttelophase-Kern vonMicrasterias umgebende Microtubuli-System, desorganisierend einwirkt. Durch die Zerstörung dieses MiÇrotubuli-Systems scheint der Zellkern seine FÄhigkeit zur Kernmigration zu verlieren.

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Influence of the Herbizide Trifluralin on the postmitotic migration of the nucleus inMicrasterias denticulata Bréb.

Summary During the phase of postmitotic cell-growth cells ofMicrasterias denticulata Bréb. were treated with Trifluralin. In a concentration range of 10^–2 to 10^–5% strong influence on the migration of the nucleus could be observed, leading to an abnormal position of the nucleus within the cell (Figs. 1B, C, D).Beside this, migration of the chloroplast was strongly inhibited. No effect could be observed on cytomorphogenesis,i.e., growth and patterning of the primary cell wall. It is suggested that Trifluralin like Colchicine, Vinblastine, IPC, and Chloro-IPC desorganizes the microtubule-system surrounding the posttelophase-nucleus ofMicrasterias. By the destruction of this microtubule-system the nucleus seems to loose its migration ability.

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Für die technische Hilfe danke ich Frau D. Neudecker. Die Untersuchungen wurden durch die Deutsche Forschungsgemeinschaft unterstützt.     

Feinstruktur von Zellwand und Plasmamembran beiMicrasterias denticulata Bréb. nach Gefrierätzung

Zusammenfassung Gefrierätz-Untersuchungen an rasch eingefrorenen sonst aber unvorbehandelten Zellen vonMicrasterias denticulata ergaben, daß die Sekundärwand aus einer fibrillenfreien Außenschicht, die möglicherweise Lipid-Charakter aufweist, und einer Fibrillenschicht aufgebaut ist.Jede der zu Bändern zusammengefügten Mikrofibrillen (mit Durchmessern bis zu 300 Å) der Fibrillenschicht besteht aus zahlreichen Elementarfibrillen, die einen ungefähren Durchmesser von 40 bis 50 Å aufweisen. In tieferen Lagen der Fibrillenschicht laufen die Mikrofibrillen um den Porus herum, während die äußerste Lage der Fibrillenschicht vom Porus durchbrochen wird. Nur diese Lage wird sekundär perforiert; der übrige Porenkanal entsteht gleichzeitig während des Sekundärwandwachstums.Die Bruchfläche der Plasmamembran ist mit zahlreichen, statistisch verteilten Partikeln bedeckt und weist Eindellungen unter jedem Porus auf. Am Rande dieser Eindellungen sind Membranlöcher festzustellen, die als Fusionsorte von schleimenthaltenden Vesikeln und der Plasmamembran gedeutet werden.

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Fine-structure of the cell wall and plasma membrane inMicrasterias denticulata bréb. after freeze-etching

Summary Cells of the algaMicrasterias denticulata, frozen in their growth medium without further pretreatment, have been examined by means of freeze-etching. The outer surface of the secondary wall as well as the side walls of the slime pores are covered with a continuous thin, fibril free layer with cleaving properties resembling those of multiple lipid bilayers. Elementary fibrils (40 to 50 Å in diameter) are shown to make up the microfibrils (200 to 300 Å in diameter), 2 to 15 of which may aggregate laterally to form the characteristic bands of secondary wall fibrils. While the microfibrils in the inner layers of the secondary wall appear to circumvent the pores those belonging to the outermost layer seem to be frequently disrupted by the pore apparatus. These observations suggest that the main part of the pore channel is formed during secondary cell wall formation. Only the outermost fibrillar layer of the secondary wall seems to be perforated after its deposition.The cleaved face of the plasma membrane carries numerous randomly distributed particles and is marked by large depressions underlying each of the pores. In the rim areas of these depressions the membrane is frequently interrupted by small holes, which are interpreted as points of fusion between the slime secreting vesicles and the plasma membrane.

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Die elektronenmikroskopischen Untersuchungen wurden in den Biological Laboratories der Harvard University, Cambridge, U.S.A., durchgeführt. Die Arbeit wurde durch die Deutsche Forschungsgemeinschaft und durch einen Health Science Advancement Award Grant 5-SO 4-FRO 6084 an die University of Colorado unterstützt.     

The distribution of microtubules in differentiating cells of Micrasterias denticulata bréb.

Summary As an extension of earlier cytophysiological and morphological studies on differentiating cells of Micrasterias denticulata, a fine structural investigation of glutaraldehyde-osmium tetroxide fixed material has been made. Special emphasis has been placed on the distribution of cytoplasmic microtubules and on their possible role in the processes of growth and differentiation. Four distinct systems of microtubules were found: (a) a band in the cortical protoplasm of the isthmus region which surrounds the nucleus; (b) several bands in the cortical protoplasm of the old half cells, with rod-like cross bridges between individual microtubules and between the microtubules and the plasmalemma; (c) clusters of microtubules near the posttelophase nucleus, some separated by intertubular structures possibly fibrils; and (d) microtubules in the internal and cortical protoplasm of differentiating half cells.This work was supported by a National Science Foundation Senior Foreign Scientist Fellowship to Dr. Oswald Kiermayer,and by funds of Training Grant 5-T1-GM-707-06 to Dr. Keith R. Porter.     

Effects of pH and temperature on the survival of coliphages MS2 and Qβ

The RNA F-specific coliphages, MS2 and Q, have been used as virus indicators in water and wastewater studies. It is therefore useful to have a good understanding concerning the effects of environmental factors on their survival in order to choose an appropriate candidate for assessing microbial safety in relation to water quality management. The effects of pH and temperature on the survival of these two coliphages were investigated. MS2 survived better in acidic conditions than in an alkaline environment. In contrast, Q had a better survival rate in alkaline conditions than in an acidic environment. The inactivation rates of both coliphages were lowest within the pH range 6–8 and the temperature range 5–35°C. The inactivation rates of both coliphages increased when the pH was decreased to below 6 or increased to above 8. The inactivation rates of both coliphages increased with increasing temperature. Q behaved peculiarly in extreme pH buffers, i.e. it was inactivated very rapidly initially when subjected to an extreme pH environment, although the inactivation rate subsequently decreased. In general, MS2 was a better indicator than Q. However, within the pH range 6–9 and at temperatures not above 25°C, either MS2 or Q could be used as a viral indicator.     

Ueber die GattungSpirotaenia Bréb

Ohne Zusammenfassung     

Ueber die GattungSpirotaenia Bréb

Ohne Zusammenfassung     

Ueber die GattungSpirotaenia Bréb

Ohne Zusammenfassung     

Ueber die GattungSpirotaenia Bréb

Ohne Zusammenfassung     

Effects of temperature and carbon dioxide on green sturgeon blood–oxygen equilibria

There are three Northeast Pacific Rivers still supporting spawning populations of green sturgeon, Acipenser medirostris, but all have been modified hydrologically and thermally by dam construction. Age 1- to 3-year-old green sturgeon, progeny of artificially spawned, wild-caught Klamath River adults, were used to assess the effects of temperature and carbon dioxide on critical hematological parameters related to evolutionary adaptations of this species to its physical environment. In vitro measurement of the effect of temperature and carbon dioxide on blood–oxygen affinity and equilibrium curve shape yielded the following data for the respective temperature treatments (11, 15, 19, and 24°C): half-saturation values (P₅₀’s, kPa, a measure of affinity) 1.26, 1.44, 1.63, 1.69 for low-PCO₂ treatments and 2.08, 2.41, 2.74, 2.94 for high-PCO₂ treatments; Bohr factors −0.322, −0.327, −0.366, −0.536; and non-bicarbonate buffer values (slykes) −6, −3, −5, −8. Temperature sensitivities (ΔH, kJ mol O₂⁻¹) between these respective temperatures were −34.20, −15.24, −6.74 for low-PCO₂ treatments and −20.05, −27.00, and −11.55 for the high-PCO₂ treatments. These data suggest that juvenile green sturgeon may tolerate moderate environmental hypoxia, moderate aerobic activity, low to moderate hypercapnia, and moderate temperature changes in their environments.     

Effects of gibberellic acid and abscisic acid on α-amylase activity and ultrastructure of aleurone cells ofAvena sativa L.

The effects of GA₃ and/or ABA on the α-amylase activity and the ultrastructure of aleurone cells in halves of seeds without embryos (embryo-less half seeds) of oats (Avena sativa L.) were studied. α-Amylase activity was detected by the starch-agar gel method in the aleurone layers of embryo-less half seeds soaked in 1 μM GA₃ solution or 100 μM GA₃+10 μM ABA solution but not in those of seeds soaked in distilled water, 10 μM ABA solution, or 1 μM GA₃+10 μM ABA solution. Ultrastructural examinations of aleurone cells with α-amylase activity showed a decrease in the number of sphaerosomes, the appearance of flattened saccules pressed to the surface of aleurone grains, and the development and transformations of the rER from a slender form to the one with wide inner spaces. In the aleurone cells in which the enzyme activity was not detected, components of the rER showed only slender profiles. The number of sphaerosomes did not decrease, and no flattened saccules appeared in the aleurone cells treated with 10 μM ABA or 1 μM GA₃+10 μM ABA.     

Effects of temperature and carbon dioxide on green sturgeon blood–oxygen equilibria

There are three Northeast Pacific Rivers still supporting spawning populations of green sturgeon, Acipenser medirostris, but all have been modified hydrologically and thermally by dam construction. Age 1- to 3-year-old green sturgeon, progeny of artificially spawned, wild-caught Klamath River adults, were used to assess the effects of temperature and carbon dioxide on critical hematological parameters related to evolutionary adaptations of this species to its physical environment. In vitro measurement of the effect of temperature and carbon dioxide on blood–oxygen affinity and equilibrium curve shape yielded the following data for the respective temperature treatments (11, 15, 19, and 24°C): half-saturation values (P₅₀’s, kPa, a measure of affinity) 1.26, 1.44, 1.63, 1.69 for low-PCO₂ treatments and 2.08, 2.41, 2.74, 2.94 for high-PCO₂ treatments; Bohr factors ?0.322, ?0.327, ?0.366, ?0.536; and non-bicarbonate buffer values (slykes) ?6, ?3, ?5, ?8. Temperature sensitivities (ΔH, kJ mol O ₂ ^?1 ) between these respective temperatures were ?34.20, ?15.24, ?6.74 for low-PCO₂ treatments and ?20.05, ?27.00, and ?11.55 for the high-PCO₂ treatments. These data suggest that juvenile green sturgeon may tolerate moderate environmental hypoxia, moderate aerobic activity, low to moderate hypercapnia, and moderate temperature changes in their environments.     

Effects of the potential allelochemical α-asarone on growth,physiology and ultrastructure of two unicellular green algae

The effects of the natural phenylpropanoid -asarone on growth pattern, photosynthesis, respiration and cell structure of two microalgae have been investigated. In cultures ofAnkistrodesmus braunii -asarone decreases in the medium and induces a lag in growth. Both phenomena were dependent on the number of cells inoculated. By contrast, in cultures ofSelenastrum capricornutum a constant decrease of the growth rate at all inocula was observed and only a slight decrease of -asarone in the medium occurred. In both algae -asarone caused an initial inhibition of photosynthesis, followed by a resumption of control values. The respiratory rate ofA. braunii was not significantly affected by -asarone, whereas inS. capricornutum respiration lowered to 60% of the control in the first 48 h and subsequently rose to values exceeding the controls by 20%. Ultrastructural observations carried out 24 and 72 h after the addition of -asarone showed modifications of cell wall inA. braunii, an increase in the number of mithocondrial profiles per cell section inS. capricornutum, and an accumulation of electron-dense deposits in the vacuoles of both algae.Author for correspondence