Langzeitkulturen von Süßwasserschwämmen (Porifera,Spongillidae) unter Laborbedingungen

Zusammenfassung Süßwasserschwämme (Spongilliden) lassen sich in 120-1-Aquarien mit Herkunftswasser der Schwämme kultivieren. Das gut durchlüftete Wasser soll nicht wärmer als 17°C sowie mit den Zusätzen Aquatonic und Schwarztorf versehen sein. Anstelle des Teichbzw. Flußwassers kann auch Leitungswasser oder eine Mischung von Leitungs- und vollentsalztem Wasser verwendet werden. Das Wasser der Aquarien ist alle vier Monate zu erneuern.Als Kulturgefäße eignen sich Glas- und Kunststoffschalen. Diese werden mittels spezieller Halter in die Aquarien eingebracht.Langzeitkulturen bieten beste Voraussetzungen für die Schwammforschung.

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Permanent cultures of freshwater sponges (Porifera, Spongillidae) in the laboratory

Summary Freshwater sponges (Spongillidae) can be cultivated in 120-1 aquariums with water from the natural sponge habitats. The well-aired water should not be warmer than 17°C and should contain Aqua-tonic and black peat. Instead of habitat water, tap water or a mixture of tap and distilled water may be used. The water in the aquariums should be renewed every 4 months.For the culture we use glass or plastic vessels. These are mounted in the aquariums by special holders.Permanent cultures offer ideal conditions for sponge research.

     

A new type of central cell in the choanocyte chambers of Pellina fistulosa (Porifera,Demospongiae)

Central cells of a hitherto unknown type, forming a continuous, perforated layer at the level of the distal collar ends in each choanocyte chamber, have been found in the choanocyte chambers of Pellina fistulosa. The collars project through the pores of the perforated central cell layer. The spaces between the collar ends and between the collars and the cone cell ring in the apopyle region are sealed by the central cell cytoplasm. The latter represents an impermeable barrier for particulate material as well as for water and thus enhances the filtration efficiency by preventing a bypass of water and particles between the collar apices.     

Der Einfluss des Wirtes in der Massenzucht auf die Qualität des EiparasitenTrichogramma evanescens bei der Bekämpfung des Maiszünslers,Ostrinia nubilalis

Zusammenfassung In vier Feldversuchen wurde die Wirksamkeit eines an den Maiszünsler besonders angepassten Stammes vonTrichogramma evanescens Westw. bei der Bek?mpfung des MaiszünslersOstrinia nubilalis Hübner geprüft. Die Parasiten wurden entweder auf Eiern der GetreidemotteSitotroga cerealella (Oliv.) oder auf Eiern der MehlmotteEphestia kuehniella Zell. gezüchtet. Die Freilassung erfolgte in den Versuchsparzellen durch Anbringen von Eikarten mit jeweils etwa 1000 parasitierten Wirtseiern an Bl?ttern von Maispflanzen in Abst?nden von 14 Metern. VierTrichogramma-Freilassungen in w?chentlichen Abst?nden mit jeweils 45000 Parasiten pro Hektar ergaben hohe Parasitierungsraten bei denO. nubilalis-Eiern und starke Verminderungen des Larvenbefalls. In den Parzellen, in denen aufS. cerealella-Eiern gezüchtete Parasiten freigelassen wurden, lagen die Parasitierungsraten zwischen 81,7 und 82,3% im Vergleich zu 63,0 und 84,3% bei den aufE. kuehniella gezüchteten Trichogrammen. Die Verminderung des bei der Ernte festgestelltenO. nubilalis-Larvenbefalls im Vergleich zur unbehandelten Kontrolle lag bei den aufS. cerealella gezüchteten Parasiten zwischen 75,5 und 94,8% verglichen mit 77,6 und 89,9% bei den aufE. kuehniella gezüchteten Tieren. Es gab somit keine signifikanten Unterschiede zwischen den beiden getestetenTrichogramma-St?mmen.

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Summary The effectiveness of a strain ofTrichogramma evanescens Westw. especially adapted to the European corn borerOstrinia nubilalis Hübner was examined in 4 field experiments. The parasites were reared on either the Angoumois grain mothSitotroga cerealella (Oliv.) or the Mediterranean flour mothEphestia kuehniella Zell. and were released in separate experimental plots by attaching egg cards, each containing about 1000 parasitized host eggs, to corn leaves at distances of 14 meters in the field. FourTrichogramma treatments at 1 week intervals using 45000 parasites per hectar per treatment resulted in high parasitization rates ofO. nubilalis-eggs and large reductions in larval damage. In experimental plots whereT. evanescens, reared onS. cerealella-eggs, were released, the parasitization rates ofO. nubilalis-eggs varied between 81,7 and 82,3%, compared with 63,0 and 84,3% forT. evanescens reared onE. kuehniella. The reduction inO. nubilalis larval infestation at the harvest in the treated plots, compared to untreated controls varied between 75,5 and 94,8% forT. evanescens that was reared onS. cerealella, compared with 77,6 and 89,8% forT. evanescens that was reared onE. kuehniella. There were no significant differences in efficiency between the two tested methods of rearingTrichogramma.

     

Laboratory studies on the effects of pollen from Bt-maize on larvae of some butterfly species

Abstract:   Three lepidopteran species were tested to determine their susceptibility against the ingestion of pollen from genetically modified maize plants. To prove the existence of dose–response relations between the applied amount of pollen (Bt-maize) and the damages on the tested larvae, a method was developed which makes it possible to feed caterpillars with defined amounts of pollen. If their food plants were contaminated with pollen of a cultivar of the Bt-176 maize-line Pieris brassicae , Pieris rapae and Plutella xylostella -larvae fed less, grew more slowly and showed a higher mortality than caterpillars of an untreated control group. The 50% lethality (LD₅₀)-values were calculated for P.xylostella (L₄) with 19.2, for P. rapae (L₂) with 39.0 and also for P. brassicae (L₂) with 139.2 pollen of the transgenic maize Pactol CB. Studies with P. brassicae -caterpillars of different larval stages indicated, that older individuals showed a higher tolerance against pollen from Bt-maize than younger ones. It must be stated on the basis of the present studies, that ingestion of non-transgenic maize pollen has neither a positive nor a negative effect on caterpillars. It becomes clear from the information presented here that it is still difficult to make general statements about the endangering of butterflies, arising from cultivation of genetically modified maize lines. Further investigations on this issue are needed. Initially, the LD₅₀-values concerning the larvae of certain butterfly species have to be determined to anticipate the risks, and in addition the distances between habitats with caterpillar host plants and maize fields, and the abundance of these plants have to be considered.     

Die Aufnahme partikulärer Nahrung beiReniera sp. (Porifera)

The choanocyte chambers of the marine spongeReniera sp. protrude with their curved outer surface free into the incurrent canals. The water is sucked into the chambers by cavities between the choanocytes. Particles up to 1 µm in diameter may enter the chambers with the water current. These particles are trapped on the outer surface of the choanocyte collars and are ingested by the choanocytes and processes of the pinacocyte epithelium of the incurrent canal system, which project into the chambers. Bigger particles are retained in the incurrent canals mainly on the outer surface of the choanocyte chambers. They are ingested by pinacocytes of the canal wall and transported to cells of the mesenchyme. The present investigation shows the great importance of the pinacocyte epithelium of the incurrent canal system for suspension feeding inReniera sp.     

Body structure of marine sponges

Summary Specimens of Haliclona elegans (Bowerbank, 1866) are covered by a thin, double layered dermal membrane extending over large subdermal spaces. The pores in the dermal membrane are formed by single porocytes with one or sometimes several pores in the center of the cell. The subjacent tissue shows a faintly developed mesenchyme and numerous big choanocyte chambers projecting into lacunar spaces of the incurrent canal system. The outer surface of the chambers is directly covered by the pinacocyte epithelium of the incurrent canal wall, which also separates them completely from the mesenchyme. Water influx into the chambers is guaranteed by prosopylar openings in the pinacocyte cover at the outer chamber surface. The chambers are connected to the excurrent canal system in the eurypylous way by wide apopyles, each of which is surrounded by a small ring of flagellated cone cells. About 15% of the choanocyte chambers in H. elegans contain central cells, which are thought to derive from migrating pinacocytes of the canal systems.     

Zur Entstehung der Gemmulae bei Ephydatia fluviatilis L. (Porifera)

Zusammenfassung Gemmula-Anlagen des Süßwasserschwamms Ephydatia fluviatilis bestehen aus Archäocyten, Trophocyten und Spongioblasten. Beschalte Gemmulae enthalten ausschließlich mit Reservestoffen gefüllte Archäocyten, die vor Fertigstellung der Gemmula-Schale zweikernig werden.Die drei lichtmikroskopisch erkennbaren Schichten der Gemmula-Schale, nämlich die Innen-, die Vakuolen- und die Außenschicht, werden nach einem zur Schwammbasis hin gerichteten Gradienten von einem hochprismatischen Spongioblasten-Epithel sezerniert. Alle Anzeichen sprechen dafür, daß es sich bei diesen Spongioblasten um temporär modifizierte Exopinacocyten handelt.Zu Beginn der Schalenbildung übernimmt ein Verband von flachen Archäocyten an der Peripherie des inneren Zellenkomplexes die Funktion der Formgebung für die entstehende Schale. Diese Zellen sezernieren in Richtung des Spongioblasten-Epithels eine nur elektronenmikroskopisch erkennbare, innere Begrenzungsschicht der Gemmula-Schale.Die in der Gemmula-Schale enthaltenen Mirkroskleren (Amphidisken) werden jeweils in einem Amphidiskoblasten im Mesenchym fertiggestellt und, nachdem Begleitzellen Kontakt zu dem Amphidiskoblasten aufgenommen haben, in das Spongioblasten-Epithel einer Gemmula-Anlage transportiert. Dort wird die Nadel aus dem Zellenkomplex freigesetzt und in die Schale eingebaut.Die Verschlußmembran im Keimporus (Mikropyle) der Gemmula-Schale wird von einer Gruppe modifizierter Spongioblasten (Mikropylen-Spongioblasten) sezerniert. Sie besteht aus der regulären, nur elektronenmikroskopisch erkennbaren, inneren Begrenzungsschicht und zwei weiteren Schichten, die mit keiner Schicht der eigentlichen Gemmula-Schale identisch sind.Die Spongioblasten flachen sich gegen Ende der Schalenbildung zu einem dauerhaften Plattenepithel ab, das auf die Oberfläche der fertigen Gemmula eine dünne Sponginhülle sezerniert.

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Gemmule development in Ephydatia fluviatilis L. (Porifera)

Summary Primordial gemmules in the freshwater sponge Ephydatia fluviatilis consist of archaeocytes, trophocytes, and spongioblasts. Once the shell has been completed the gemmules contain only archaeocytes filled with food reserves; they become binucleate before completion of the shell.The three layers of the gemmule shell discernible in the light microscope — the inner, vacuolar, and outer layers — are secreted by a highly prismatic spongioblast epithelium along a gradient from the apex to the base of the sponge. All the evidence indicates that these spongioblasts are temporarily modified exopinacocytes.Shell formation is initiated when a group of flat archaeocytes at the periphery of the inner cell complex assumes the function of establishing the shape of the shell. That is, they secrete toward the spongioblast epithelium a boundary layer, detectable only electron microscopically, that marks the inner surface of the shell.Each of the microscleres (amphidisks) in the gemmule shell is formed within an amphidiskoblast in the mesenchyme; when auxiliary cells have contacted the amphidiskoblast, they move together to the spongioblast epithelium in a region of the shell. There the spicule is released from the cell complex and incorporated into the shell.The membrane that closes the pore (micropyle) of the gemmule shell is secreted by a group of modified spongioblasts (micropyle spongioblasts). It consists of a continuation of the inner boundary layer lining the shell itself, detectable only electron microscopically, plus two other layers not identical with any layer of the shell.Toward the end of shell formation the spongioblasts flatten, creating a permanent pavement epithelium that secretes a thin envelope of spongin over the surface of the completed gemmule.

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Abkürzungen AC Archäocyte - AD Amphidiske - ADB Amphidiskoblast - AF Achsenfaden - AS Außenschicht der Gemmulaschale - bSpP basale Sponginplatte - BZ Begleitzelle - D Dotterkorn - Di Diktyosom - EnPC Endopinacocyte - ExPC Exopinacocyte - fAC flache Archäocyte - hS homogene Schicht - IS Innenschicht der Gemmulaschale - K Zellkern - KF Kollagenfibrille - KGK Kragengeißelkammer - Kn Kanal - Mi Mitochondrium - MM Mikropylenmembran - MSpB Mikropylenspongioblast - N Nukleolus - Nd Nadel - oS osmiophile Schicht - PE Plattenepithel - rAF radiärer Achsenfaden - rER rauhes endoplasmatisches Reticulum - RVS Randzone der Vakuolenschicht - Sp Spongin - SpB Spongioblast - SpH Sponginhülle - TC Trophocyte - Ves Vesikel - VS Vakuolenschicht - VV Verdauungsvakuole Die Arbeit wurde durch Mittel der Deutschen Forschungsgemeinschaft gefördert. Herrn Professor Dr. N. Weissenfels danke ich für die freundliche Unterstützung und Förderung der Arbeit. Für technische Assistenz danke ich Frau M. Geis, Frau U. Müller, Frau I. Nüssle und Frau B. Zarbock     

Effects of beech (Fagus sylvatica), ash (Fraxinus excelsior) and lime (Tilia spec.) on soil chemical properties in a mixed deciduous forest

Background and aims

We investigated the genetic diversity of arbuscular mycorrhizal fungi (AMF) in soils and the roots of Phalaris aquatica L., Trifolium subterraneum L., and Hordeum leporinum Link growing in limed and unlimed soil, the influence of lime application on AMF colonization and the relationship between AMF diversity and soil chemical properties.

Methods

The sampling was conducted on a long-term liming experimental site, established in 1992, in which lime was applied every 6 years to maintain soil pH (in CaCl₂) at 5.5 in the 0–10 cm soil depth. Polymerase chain reaction, cloning and sequencing techniques were used to investigate the diversity of AMF.

Results

Altogether, 438 AMF sequences from a total of 480 clones were obtained. Sequences of phylotypes Aca/Scu were detected exclusively in soil, while Glomus sp. (GlGr Ab) and an uncultured Glomus (UnGlGr A) were detected only in plant roots. Glomus mosseae (GlGr Aa) was the dominant AMF in the pastures examined; however, the proportion of G. mosseae was negatively correlated with soil pH, exchangeable Ca and available P. Generally, diversity of the AMF phylotypes was greater in the bulk unlimed soil and plants from this treatment when compared to the limed treatments.

Conclusions

Long-term lime application changed soil nutrient availability and increased AMF colonization, but decreased AMF phylotype diversity, implying that soil chemistry may determine the distribution of AMF in acid soils. Future studies are required to explore the functions of these AMF groups and select the most efficient AMF for sustainable farming in acid soils.     

Die Entstehung der Gemmula-Schalen bei Spongilla fragilis Leidy (Porifera)

Zusammenfassung Die Dauerstadien des Süßwasserschwamms Spongilla fragilis bestehen aus mehreren, mit einer kompakten Innenschicht versehenen Einzelgemmulae, die durch zwei weitere Schalenschichten (Kästchen- und Außenschicht) miteinander verkittet sind.Die Einzelgemmulae werden in geringem zeitlichen Abstand dicht nebeneinander angelegt. Sie besitzen zunächst ein eigenes Spongioblasten-Epithel, das die Innenschicht der Schale sezerniert. Während die Kästchenschicht aufgelagert wird, nehmen die Spongioblasten benachbarter Gemmula-Anlagen Kontakt auf und bilden dann ein einheitliches Epithel an der Oberfläche der Gemmula-Gruppe. Jeder Spongioblast sezierniert eine Kästchenreihe; deren radiäre Wände entstehen jeweils zwischen zwei benachbarten Spongioblasten.Die Mikropylenmembran liegt am Grunde eines Porusrohres, dessen Wand eine Fortsetzung der Gemmula-Schale darstellt. Das Porusrohr ist an seinem distalen Ende durch eine weitere, dünne Membran verschlossen. Die proximal gelegene Mikropylenmembran wird von modifizierten Spongioblasten (Mikropylen-Spongioblasten) gebildet und stimmt in ihrem Bau mit der Mikropylenmembran von Ephydatia fluviatilis weitgehend überein.

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Development of the gemmule shells in Spongilla fragilis leidy (Porifera)

Summary The overwintering stages of the fresh-water sponge Spongilla fragilis consist of several single gemmules, each covered by a compact inner shell layer; the group is cemented together by two additional layers (the compartmented layer and the outer layer). The individual gemmules are formed in close proximity, within a short period of time. Initially each is enclosed in its own spongioblast epithelium, which secretes the inner layer of the shell. As the compartmented layer is being built up over this, the spongioblasts of adjacent gemmule primordia come into contact, eventually forming a continuous epithelium over the surface of the gemmule group. Each spongioblast secretes a row of compartments, the radial walls of which are produced between adjacent spongioblasts. The micropyle membrane is situated at the base of a pore tube, the wall of which is continuous with the gemmule shell. The pore tube is closed at its distal end by another, thin membrane. The more proximal micropyle mebrane is formed by modified spongioblasts (micropyle spongioblasts); its structure closely resembles that of the micropyle membrane of Ephydatia fluviatilis.

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Abkürzungen AC Archäocyte - äS äußere Schicht der Porusrohr-Membran - AS Außenschicht der Gemmula-Schale - bSP basale Sponginplatte - D Dotterkorn - EPC Exopinacocyten-Epithel - fAC flache Archäocyte - G Gemmula - GA Gemmula-Anlage - hS homogene Schicht - iS innere Schicht der Porusrohr-Membran - IS Innenschicht der Gemmula-Schale - K Zellkern - KF Kollagenfibrille - KS Kästchenschicht - MM Mikropylenmembran - MP Mikropyle - MSB Mikropylen-Spongioblast - N Nukleolus - Nd Nadel - oL osmiophile Lamelle - oS osmiophile Schicht - PD Pinacoderm - PR Porusrohr - PRM Porusrohr-Membran - PRW Porusrohr-Wand - rER rauhwandiges endoplasmatisches Reticulum - RKS Randzone der Kästchenschicht - SB Spongioblasten-Epithel - SR Subdermalraum - ÜS Übergangsschicht - VV Verdauungsvakuole Die Arbeit wurde durch Mittel der Deutschen Forschungsgemeinschaft gefördert. Herrn Professor Dr. N. Weissenfels danke ich für zahlreiche Hinweise und Ratschläge bei der Erstellung der Arbeit. Für technische Assistenz danke ich Frau M. Geis, Frau I. Nüssle, Frau U. Müller und Frau B. Zarbock