Die submikroskopische Struktur der Assimilatleitbahnen von Polytrichum commune

Summary In the young part of the stem of Polytrichum commune the protoplasts of the two types of conducting cells, the leptoids and parenchyma cells, are nearly identically equipped with cell organelles and cytoplasmic structures. Both types contain a nucleus, chloroplasts, mitochondria, and dictyosomes. The endoplasmic reticulum builds characteristic cisterns in form of hollow cylinders extending from one end wall to the other. The cisterns are connected with many plasmodesmata, which occur only in the end walls. Leptoids have oblique end walls with 16 to 20 plasmodesmata per m², and parenchyma cells show cross walls perpendicular to the axis with 9 to 12 plasmodesmata per m².Since the leptoids are supposed to be the pathways for the longitudinal transport of assimilates (Eschrich and Steiner, 1967, 1968), it is of interest that early in their development these elements undergo a change in their protoplasmatic structure. Two to 3 cm below the apical cell the protoplasts degenerate and show lysosome-like structures. The endoplasmic reticulum and other structures are deformed or dissolved; the plasmodesmata are constricted by callose deposits. At the same level the parenchyma cells still retain the original structure of their protoplasts.Thus, assimilates moving upward in one row of leptoids may penetrate the whole lumen of the leptoids at lower levels, but they are restricted to the cisterns of the endoplasmic reticulum at higher levels of the stem.     

Zur Entwicklungsgeschichte des Sporophyten einiger Marchantiales

Ohne ZusammenfassungMit 33 Textabbildungen.     

Spermatogenesis in Polytrichum juniperinum

Summary Spermatogenesis in Polytrichum juniperrinum includes a series of precise and coordinated morphogenetic movements among the organelles of the androcyte. The basal bodies, the underlying microtubules, and the multilayered structure (MLS) are positioned as an integrated unit at the periphery of the cell, and the nucleus migrates into contact with them. The shape of the nucleus begins to change, with the formation of an anterior projection, or beak. The mitochondrial sheath that has coalesced on the plastid divides to form the apical body, and elongation of the nucleus begins. The posterior basal body and one microtubule undergo lateral displacement from the rear forward, as elongation of the nucleus and the microtubules continues. The mitochondrial mass that is now the apical body grows rearward along the side of the elongated nucleus, and the two groups of microtubules in the MLS rearrange themselves. The lower elements of the MLS also participate in the morphogenetic rearrangement. By the time the nucleus has elongated once around the cell and the apical body has begun it s rearward growth, the lower elements of the MLS are found only beneath the anterior basal body. Subsequently these layers disappear from this location also.     

Rindenzellen von Federn im Elektronenmikroskop

Zusammenfassung An Querschnitten von Federästen zweier Vögel (Gallus und Pharomacrus) wurden die Rindenzellen im Elektronenmikroskop untersucht. Sie treten in zwei durch übergänge verbundenen Querschnittsformen auf: einerseits stark abgeplattet mit dichtem Keratinmantel und spaltförmigem Intramoenialraum, andererseits unregelmäßig polygonal umrissen mit Zerklüftung der Tonofibrillenmasse Über das ganze Zellareal hin in grobe Bündel. In beiderlei Zellen verlaufen die Tonofibrillen nach der Länge des Federastes, in Übereinstimmung mit der Aussage der Polarisationsoptik. Die Rindenzellen sind mit Membran bekleidet. An den Grenzen sich berührender Zellen erscheint zwischen den beiden Membranen eine Mittellamelle (central component von Filshie u. Rogers, 1962), die als Kittschicht gedeutet wird, welche die Nachbaren zusammenhält. Auf beiden Seiten der Mittellamelle findet sich eine helle Zone von etwa 8 nm Dicke, die bis zur Membran reicht; ihre Deutung ist fraglich. Die geschilderte Zellgrenzstruktur gilt sowohl für den flächigen Kontakt benachbarter Zellen als auch für die Verzahnung längs aufeinanderfolgender. Verzahnung gibt sich am Zellquerschnitt in der Anwesenheit von rundlichen intrazellulären Arealen zu erkennen, die von der Zellgrenzstruktur umschlossen sind; es handelt sich bei ihnen um Querschnitte von Zellfortsätzen, mit denen die eine Zelle in die andere eindringt.Bei beiden untersuchten Formen finden sich luftführende Melaningranula, über deren Bau später berichtet werden soll.     

Polyunsaturated hydrocarbons from Polytrichum commune spores

Polytrichum commune Hedw. spores were found to contain the polyunsaturated hydrocarbons normal all-cis-6,9,12,15-heneicosatetrane (20· ± 0·5 μg/100 mg spores) and normal all-cis-3,6,9,12,15-heneicosapentaene (22·5 ± 1·2 μg/100 mg spores), N- alkanes were present only in minor amounts.     

Der Jahresgang von Neuston im Golf von Neapel

The annual fluctuations in the occurrence of 91 taxa which were identified, made the recognition of 4 main seasonal populations possible. Trends were observed, as well as analogies to other patterns of distribution. On an average, more than half of the fauna was displaced from month to month, but the variation in the density of subtropical neuston appeared to be less over an annual period than it was during the day, and from region to region. The dominance of certain species and occurrence of neuston throughout the year demonstrated, that regionally at least a biocoenosis exists continously at the surface of the sea.     

Tyndallblau-Struktur von Federn im Elektronenmikroskop

Summary The normal development and cytology of the pineal organ in the newt, Taricha torosa has been described in detail. Particular emphasis has been placed on the origin of the initial pineal bud in the embryonic diencephalic roof, and the manner in which new pineal cells are proliferated in a zone surrounding the orifice of the developing pineal vesicle. These new cells apparently migrate into the walls of the enlarging vesicle and a certain number undergo progressive differentiation to become photoreceptor-like pineal sensory cells; the highest degree of this differentiation being obtained by cells whose processes protrude into the anterior, posterior, and lateral margins of the vesicle lumen.The well-formed, wide-lumened vesicle typical of early larval stages has thusfar not demonstrated any detectable cytological alterations under the influence of light, dark, pressure, or chemical stimulating agents we have employed. Within a few weeks, this young larval vesicle becomes flattened to assume the appearance of a more glial vascularized organ. In adult pineal organs it has been possible to observe aldehyde fuchsin-positive accumulations in the processes of supportive cells terminating near capillary walls. Other aspects of adult pineal cytology and innervation have also been considered in this report.A series of implants of embryonic pineal primordia into older larval host eye chambers and tailfins has given information on the development of vesicles in these sites under the influence of varying amounts of diencephalic roof tissue included with the grafts. A tentative hypothesis has been formulated to account for the tendency of a single primordium to differentiate into a larger than normal pineal mass when implanted into the tail mesenchyme with a moderate amount of diencephalic roof tissue. This hypothesis brings into focus the normal growth characteristics of the young organ developing from a broad initial pineal field and their possible modification under the influence of surrounding tissues during normal ontogeny.Incidental to the main purposes of the study, observations have been made on the pigment behavior of larvae carrying supernumerary pineal implants. These observations are discussed in the light of recent proposals by other authors.With technical assistance of Mr. Charles Cintron, Mr. Gary Clark, Miss Jean Ewalt, and Mr. Paul Johnson. The author has also been fortunate to have the interest and suggestions of Dr. Stuart Smith. Since a portion of this study was accomplished at the Zoological Laboratory, Utrecht, Holland, special thanks are due the members of that organization for their hospitality and technical advice.Portions of this research were supported by a post-doctoral fellowship (BF7283-C) from the United States Public Health Service, a research grant (G-14423) from the National Science Foundation, and grants from the University of Colorado Council on Research and Creative Work.     

Schliffe von vogel-eischalen im dunkelfeld

Zusammenfassung Die taxionomisch geregelte Schichtung der Kalkschale des Vogeleies wird wesentlich durch Anwesenheit und Menge der Einschlusse bestimmt, sei es, daß Globularinklusionen allein auftreten oder neben ihnen Spaltinklusionen. Diese Umstände lassen sich am besten im Dunkelfeld an Dünnschliffen ermitteln, wobei Auskochen der Schliffe in Kalilauge die Spaltinklusionen optisch zum Verschwinden bringt. Das Verhalten der Einschlüsse wird an einigen Beispielen vorgeführt. Weiter erleichtert das Dunkelfeld, das Muster des Schalenkalkes an der Anordnung der Inklusionen zu erkennen, was an Quer- und Flachschliffen der StrauBen Eischale für Kegel- und Säulenlage erläutert wird. Vergleich der Befunde im Dunkelfeld mit jenen beim Phasenkontrastverfahren und im Polarisationsmikroskop lassen das Wesen der sog. trüben Dreiecke in den Kegeln der Straußen-Eischale klar erkennen.

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Summary The taxionomically ordered stratification of the avian egg shell is essentially determined by presence and quantity of the inclusions, may be that only appear globular inclusions or besides them cleft inclusions. These circumstances are ascertainable the best on thin ground sections in dark field whereby boiling of the sections in potash-solution let dis appear optically the cleft inclusions. Some examples illustrate the situations of the inclusions. Farther the dark field lightens to perceive the pattern of the shell calcite, indicated by the arrangement of the inclusions; this will be explained on transverse and tangential ground sections of the Struthio egg shell for the cone- and the column-layer. Comparison of the statements in dark field with them in phase contrast and polarization microscope show clearly the nature of the troubled triangles in the cones of the Struthio egg shell.

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Herrn Professor Dr. W. E. Ankel zum 70. Geburtstage.     

Further Notes on Polytrichum commune L.

Abstract

It baa been show that the one-third divergance of the 1eaf-scale in the rhizome and middle regions is bound up with parallel type of segmentation at the apex, while the encroaching type result in higher divergence.

The general arrangement of the tissues in the oil is influenced by the type of apical aegmentation. The delineation of the primary aegments is soon lost, on account of lateral overlapping, but it can be seen that in the rhizome the three rows of radial plates represent the median regions of the aegments and correspond with the vein region in the acale leaves with which they are connected. As the axis grows, rhizoids, rhizoid wicks and sometimes branch buds are developed from epidermal cells exterior to the radial strands. This, coupled with the fact that the cells of these strands contain a larger amount of starch and other organic materials than the other regions of the cortex, indicates that they are the main conducting channels between the branches and the rhizoid system and the central conducting column.

In the middle region, the primary aegmentation is fundamentally the same as that of the rhizome, the parallel type being maintained until green leaves appear. The chief difference lies in the cell division, which is more frequent and accompanied by a strengthening of the cell walls of the cortex and a concentration of hydroids to the centre In the region corresponding with that occupied by the radial strands, groups of smaller cells forming rudimentary leaf traces can sometimes be distinguished. These are comparable with the more definite leaf traces described by Goebel (1906) in the case of Dawsonia superba R.Br., a 1arge form, 30-40 cm. long, found in Australia and New Zealand.

In the green-leaved region the change to the encroaching type of segmentation has taken place, and is accompanied by increased overlapping and further differentiation of tissues of the leaf trace and other tissues of the axis.     

Phylogeography of five Polytrichum species within Europe

Using allozymes and microsatellites we have analysed the genetic structure among European populations for several Polytrichum species to infer relevant factors, such as historical events or gene flow, that have shaped their genetic structure. As we observed low levels of genetic differentiation among populations, and no decreasing levels of genetic variation with increasing latitude within most of the examined species, no genetic evidence was obtained for a step-wise recolonization of Europe from southern refugia after the latest glacial period for P. commune , P. uliginosum , P. formosum and P. piliferum . The near absence of population substructuring within these species does indicate that extensive spore dispersal is the most important factor determining the genetic structure among European Polytrichum populations. Gene flow levels have apparently been sufficient to prevent genetic differentiation among populations caused by genetic drift, and to wipe out any genetic structure caused by the postglacial recolonization process. On the other hand, increased genetic differentiation of alpine P. formosum populations suggests that mountain ranges might restrict gene flow significantly among Polytrichum populations. In contrast to most examined Polytrichum species, P. juniperinum showed high levels of genetic differentiation and a profound genetic structure. Assuming that gene flow is not more restricted in P. juniperinum , these findings suggest that this species has recolonized Europe after the latest glacial period from two different refugia, one possibly being the British Isles.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society 2003, 78, 203–213.     

Erhaltungszuchten von Amphibien im deutschsprachigen Raum

The global amphibian crisis is demonstrated in the number of endangered species and the hazard criteria. The development of an international response to this crisis from the Amphibian Conservation Action Plan to the Amphibian Ark is described and set forth the breeding community in the German speaking region by zoological institutions, private amphibian keepers and a school. The regulations created by a community of many zoo organizations are explained. The procedure and the educational backgrounds of the Gerhart-Hauptmann-Secondary school as part of the breeding program are presented to the reader with the successful breeding of Neurergus kaiseri.     

Cytochemischer Nachweis von saurer Desoxyribonuclease im Cytoplasma von Blutzellen

Zusammenfassung Es wird ein cytochemisches Verfahren zum Nachweis der sauren Desoxyribonuclease in Blutzellen beschrieben. Das Prinzip des Nachweises beruht auf der Depolymerisierung von Desoxyribonucleinsäuren der Inkubationslösung zu Mononucleotiden, deren in 3-Stellung stehendes Phosphation durch ebenfalls der Inkubationslösung zugegebene saure Phosphatase freigesetzt und mit dem Verfahren der Schwermetallsalz-Präzipitation in Form des Bleisulfids mikroskopisch erkennbar dargestellt wird.In allen Leukocytenarten, Erythroblasten, Reticulocyten und Thrombocyten ist saure Desoxyribonuclease nachweisbar. Die Spezifität der Methode wird diskutiert.

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Cytochemical staining for acid deoxyribonuclease in cytoplasm of blood cellsI. Method

Summary A technique for the cytochemical demonstration of acid deoxyribonuclease in blood cells is presented in this paper. Blood slides were incubated in a medium containing highly polymerized DNA, lead nitrate an acid phosphatase. DNA is depolymerized by the deoxyribonuclease and mononucleotides are formed. These serve as substrate for exogenous acid phosphatase, which release phosphate ions. The latter are locally precipitated by lead ions.Acid deoxyribonuclease occurs in all leucocytes, erythroblasts, reticulocytes and thrombocytes. The specifity of this method is discussed.

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Die Untersuchungen wurden mit Sachbeihilfen der Deutschen Forschungsgemeinschaft durchgeführt.     

Riesenzellen im Bulbus olfactorius von Teleosteern

Zusammenfassung Im sessilen Bulbus olfactorius von Teleosteern werden große Nervenzell-Somata als bulbäre Riesenzellen beschrieben. Sie treten bei Arten mit einem gestielten Bulbus nicht auf. Ihre Anordnung geht parallel mit dem bulbären Verlauf des Nervus terminalis. Holmgrens Kaudale Zellgruppe bzw. das Kerngebiet des Nervus terminalis (Scharrer) ist eine häufig anzutreffende Gruppierung dieser Zellen am caudalen Bulbusende. Es wird die Möglichkeit erörtert, ob die bulbären Riesenzellen nicht den Ganglienzellen des Nervus terminalis verwandte Strukturen darstellen.

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Giant cells in the olfactory bulb of teleostean fishes

Summary Large nerve cell somata are described as bulbar giant cells in the sessile olfactory bulb of teleostean fishes. They are not found in species with a stalked olfactory bulb. They are arranged along the bulbar course of the nervus terminalis. In the Kaudale Zellgruppe of Holmgren and the Kerngebiet des Nervus terminals of Scharrer a greater part of these giant cells lie at the caudal end of the bulb. It is discussed if these cells are related to the ganglion cells of the nervus terminalis.

     

Funktionsstrukturen im Oocytenkern von Locusta migratoria

Examination of living oocyte nuclei of Locusta migratoria has revealed the presence of thread-like struktures. They are paired and are thought to be the uncoiled chromosomes since they are broken into fragments by treatment with DNase. The greater part of the threads carries lateral loops like the lampbrush chromosomes of Amphibia (Fig. 14). A smaller part has no loops hut bears a series of conspicious granules with bright appearance under positive phase contrast optics (pearl-string segments) (Fig. 2). — The visibility of the chromosomes has been investigated in solutions with several ions. In hypertonic media the chromosomes contract, the granules fuse, and the pearl-string segments become lumpy (Fig. 21). In nitrogenous atmosphere and if kept at low temperature the pearl-string structures are likewise transformed into a few lumps (Fig. 19). After return to normal conditions they reconstitute their characteristic beaded appearance. — In autoradiographs obtained by injection of H³-uridine into the body cavity and by incubation of isolated nuclei in vitro, a rather uniformly distributed labelling occurs over the oocyte nuclei up to 30 min incubation time (Fig. 23). With prolonged incubation the activity of the pearl-string segments becomes more intense than the labelling of the lampbrush chromosomes (Fig. 24). After treatment with actinomycin RNA synthesis is stopped, the pearl-string axes and the lampbrush chromosomes contract, and the granules disappear more and more (Figs. 25-28). — The pearlstring segments look very much like the nucleoli in the oocytes of Amphibia, where the nucleolar substance is likewise distributed as a series of beads of rather uniform size on an axis. Therefore, the pearl-string structures may have nucleolar function in Locusta too. If so, the only difference to the Amphibian nucleoli would be the continued attachment to the lampbrush chromosomes.