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  • Springer  (89,609)
  • 1995-1999
  • 1980-1984  (44,784)
  • 1975-1979  (44,825)
  • 1983  (44,784)
  • 1978  (44,825)
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  • 1995-1999
  • 1980-1984  (44,784)
  • 1975-1979  (44,825)
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  • 1
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le sac infrabuccal d'Acromyrmex octospinosus retient des particules en suspension dans la nourriture, dont le diamètre peut n'être que de 10 μm. Cette poche sert de réceptacle pour des matières prélevées sur les jardins à champignons, sur le corps même des fourmis, et pour de la cire léchée sur les feuilles utilisées dans la culture du champignon. Les pelotes rejetées de la poche infrabuccale des ouvrières contiennent des spores de champignons contaminants. Elles ont toujours été retrouvées loin des meules, le plus souvent sur les tas de détritus. Les femelles vierges cependant régurgitent leurs pelotes sur les jardins à champignons. Le champignon des fourmis a pu être cultivé sur des plaques d'agar, sur lesquelles des pelotes d'ouvrières ont été étalées. Les ouvrières n'ont pas été capables de débuter une nouvelle culture de champignons, mais l'utilisation par les reines du sac infrabuccal pour inséminer les nouveaux jardins lors des fondations de colonie peut être considérée comme un cas particulier d'un comportement plus général.
    Notes: Summary The leaf-cutting antAcromyrmex octospinosus was shown to filter out into its infrabuccal pocket from liquid food, particles down to ten μ in diameter. The pocket acted as a receptacle for material licked from the ants' fungus garden and from their own bodies, and for leaf wax licked from leaves used for fungus culture. The infrabuccal pellets of worker ants, which might contain contaminating fungal spores, were always found away from the fungus garden and mostly on the refuse dump. Virgin queens however, regurgitated their pellets onto the fungus garden. Pellets regurgitated by worker ants were streaked onto agar plates, and from these the ant fungus was cultured. Worker ants were not able to start a new fungus garden, but the use of the infrabuccal pocket by queens to transmit the ant fungus to newly founded colonies can be seen as part of a general behaviour pattern.
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  • 2
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    Insectes sociaux 25 (1978), S. 303-313 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In den Staaten vonOdontotermes stercorivorus (Sj.) entstehen Nymphen nur einmal im Jahr. Sie treten jedoch nicht in allen Nestern auf und ihre Anzahl pro Nest schwankt erheblich. Nymphen erscheinen im Nest schubweise. Sie entstehen zusammen mit Larven in Eikammern, die der Königinkammer benachbart liegen. Die alten Nymphen entfernen sich von den Eikammern und die geflügelten Geschlechtstiere sammeln sich schliesslich in Kammern an der Peripherie der Nester. Äussere Faktoren, insbesondere das Klima und das Nahrungsangebot könnten alljährlich die Entstehung von Nymphen auslösen, die jahreszeitlich artspezifisch festliegt. Ob jedoch in einem bestimmten Jahr in den einzelnen Nestern Nymphen auftreten oder nicht und in welcher Anzahl scheint abhängig zu sein von internen Faktoren.
    Notes: Summary In colonies ofOdontotermes stercorivorus (Sj.), nymphs appear only once annually. They are not to be found in all colonies of a similar size and their numbers show great variation from nest to nest. Nymphs originate and develop in batches, together with larvae, in egg chambers near to the queen. The older nymphs move from the egg chambers and the alatae congregate in chambers at the periphery of the nest. External factors, such as climate and foraging conditions, may be important as releasers of the annual nymphal production, the time of which is species specific. But whether or not nymphs occur in a nest in any particular year and in what numbers, seems to be more dependent on internal factors.
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  • 3
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary The authors investigated the possible existence in ants of differences in the amounts of sugar food given to the queen and worker larvae by the workers. Experimental groups of the AntPlagiolepis pygmaea, rearing worker biased or queen biased larvae, were fed on honey containing radio-actively labeled gold (Au108). Upon introduction of the tracer, the groups were incubated at 26° for 4, 6, 8, 10 and 12 days. The radio-activity of the larvae was measured after 25, 48 and 76 hours. This permits a comparative estimation of the quantity of material which has been given to larval feeding from the crop of the workers. It can be only some radio-active honey ingested by the workers; but the salivary secretions of the larvae could also, in the interval, add a small quantity to the honey. The results show that,weight for weight, the queen larvae receive much more food coming from crop than the worker larvae. This difference, which is very slight until the 8th day of incubation, becomes obvious on the 9th day and reaches its maximum on the 10th and 11th days: the queen larvae receive, at this time, up to 6 times more food, weight for weight, than the worker larvae. We note that it is at the moment when the weight increase of the queen larvae is at its highest that the quantitative difference in the received sugary matter, weight for weight, is also at its highest. The authors think that the very high sugar content of the diet of queen larvae does not come into play until after caste determination has occurred.
    Notes: Résumé Les auteurs ont recherché s'il existe, chez les Fourmis, des différences dans les quantités d'aliments sucrés données par les ouvrières aux larves de reines et aux larves douvrières. Des groupes expérimentaux de la FourmiPlagiolepis pygmaea, élevant des larves d'ouvrières ou des larves de reines, ont été nourris avec du miel contenant de l'or radioactif (Au108). Lors de l'introduction du radio-élément, les groupes sont élevés à 26°C depuis 4, 6, 8, 10 et 12 jours. La radio-activité des larves est mesurée au bout de 25, 48 et 76 heures. Elle permet une estimation comparative de la quantité de substances qui a servi à l'alimentation des larves, en provenance du jabot des ouvrières. Il peut s'agir seulement du miel radio-actif ingéré par les ouvrières; mais des sécrétions salivaires ont pu aussi, dans l'intervalle, s'y ajouter en petite quantité. Les résultats montrent que,par unité de poids, les larves de reine reçoivent beaucoup plus de substances provenant du jabot que les larves d'ouvrières. Peu sensible ou faible jusqu'au 8e jour de la mise en élevage, cette différence devient très nette à partir du 9e jour, et atteint son maximum les 10e et 11e jours: les larves de reines reçoivent alors, par unité de poids, jusqu'à 6 fois plus de nourriture que les larves d'ouvrières. On constate que c'est au moment où la croissance pondérale des larves de reines est la plus importante que la différence quantitative dans les matières sucrées reçues, par unité de poids, est la plus forte. Les auteurs estiment que cette alimentation très riche en sucre des larves de reines n'intervient qu'après le déterminisme de la caste.
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  • 4
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    Insectes sociaux 25 (1978), S. 323-337 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Honigbienen bevorzugen bestimmte Nistplatzeigenschaften. Die folgenden Bevorzugungen wurden herausgefunden («〉» bedeutet «bevorzugt gegenüber»): Höhe des Nestes, 5〉1 m; Fläche des Eingangs, 12,5〉75 cm2; Lage des Eingangs, Boden〉Spitze; Richtung des Eingangs, nach Süden〉nach Norden; Raum der Nesthöhle, 10〈40〉100 Liter. 2. Die Daten deuten darüber hinaus an, dass Honigbienen Nesthöhlen bevorzugen, die vorher bewohnt waren, oder die weiter als 300 m vom Mutterstock entfernt sind. 3. Exponierte und gut sichtbare Nistplätze werden schneller bezogen als weniger exponierte und weniger gut sichtbare Plätze. Wahrscheinlich hat dies aber seinen Grund darin, dass diese Plätze leichter entdeckt werden, nicht weil sie echt bevorzugt werden. 4. Keine Bevorzugung wurde für die folgenden Variablen gefunden: Form des Eingangs (Schlitz vs. Kreis), Form der Nesthöhle (Quader vs. hohe Rechtecksäule), Zugigkeit der Höhle (zugfrei vs. zugig) und Trockenheit (feucht vs. trocken). Wahrscheinlich sind Zugigkeit und Trockenheit der Höhle für die Biene wichtig. Da die Bienen jedoch ihr Nest abdichten und wasserdicht machen können, sind sie — was diese Nistplatz-Variablen angeht — nicht so wählerisch als gegenüber jenen, die sie nicht ändern können. 5. Dieser komplexe Prozess der Nistplatzwahl kommt der Honigbiene offensichtlich in verschiedener Weise zugute, z. B. zur Erleichterung der Verteidigung und Hygiene des Stockes, der Vereinfachung beim Nestbau und bei der Kontrolle des Mikroklimas, sowie zur Minderung der Futterkonkurrenz mit dem Muttervolk.
    Notes: Summary 1. Honey bees exhibit preferences in several nest site properties. The following preferences were identified («〉» means «preferred to»): nest height, 5〉1 m; entrance area, 12.5〉75 cm2; entrance position, bottom 〉top of nest cavity, entrance direction, southward〉northward; nest cavity volume, 10〈40〉100 liters. 2. The data also suggest preferences exist for previously inhabited nest cavities and for nest sites beyond 300 m from the parent colony. 3. Nest sites with high exposure and visibility were occupied more rapidly than sites with low exposure and visibility. However, this difference probably reflects differential ease of nest site discovery rather than a preference for exposed nest sites. 4. No preferences were found in the following variables: entrance shape (slit vs. circle), nest cavity shape (cube vs. tall parallelepiped), cavity draftiness (sound vs. drafty), and cavity dryness (wet vs. dry). Cavity draftiness and dryness are probably important to bees, but because bees can seal and waterproof their nests, they may be less demanding about these two nest site variables than about those they cannot modify. 5. The complex process of nest site selection apparently benefits a honey bee colony in several ways, including facilitation of colony defense and hygiene, simplification of nest construction and microclimate control, and reduction of foraging competition with the parent colony.
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  • 5
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Nous avons réalisé une étude expérimentale du développement de grandes larves ayant hiverné, chez 4 espèces deMyrmica. Utilisant une gamme de températures de 15°C à 25°C, nous avons montré que: 1. Il n'y a pas de différences entre les espèces quant à l'effet de la température sur les durées de développement. Toutes suivent le modèle: log. durée de développement =a-b T°C, avec la même valeur pour b. Ceci donne un Q10 effectif d'environ 3,1. Ce résultat est en accord avec les estimations de respirométrie chez les ouvrières de fourmis. 2. Les valeurs de a diffèrent de façon significative entre la plupart des espèces, ce qui confirme la différence intrinsèque que nous avions démontrée à la température constante de 22,5°C dans un précédent travail. Les durées de développement larvaire peuvent être ainsi classées, de la plus rapide à la plus lente:Myrmica ruginodis Nyl.,Myrmica rubra L.,Myrmica scabrinodis Nyl. etMyrmica sabuleti Meinert. A toutes les températures, il faut 1,5 fois plus de temps àM. sabuleti qu'àM. ruginodis pour qu'une grande larve ayant hiverné se transforme en nymphe blanche. 3. Nous n'avons pas observé de grandes différences dans la survie des larves et la production des reines, aux températures utilisées dans nos expériences. La plupart des espèces survivent le mieux à 22°C environ. 4. Les résultats sont brièvement discutés en fonction de la distribution écologique des 4 espèces dans le Sud de l'Angleterre. 5. Nous discutons les effets possibles d'un régime de température variable. Nous suggérons que l'amplitude des variations peut ne pas avoir un effet important alors que la périodicité des variations pourrait avoir un effet plus important.
    Notes: Summary The effect of temperature upon the development of large hibernated larvaæ of fourMyrmica species has been tested experimentally. Over the viable temperature range of 15–25°C, it was found that: 1. There are no differences between the species in the effect of temperature upon development times. All fit the model log Dev. time=a-b T°C with a common value for b. This gives an effective Q10 of about 3.1 which agrees with respirometrical estimates for worker ants. 2. The value for the intercept (a) differs significantly between most species confirming the intrinsic difference that has been demonstrated at a constant 22.5°C in previous work. The development times of larvæ can be ordered from fastest to slowest being:Myrmica ruginodis Nyl.,Myrmica rubra L.,Myrmica scabrinodis Nyl. andMyrmica sabuleti Meinert. At any temperature it takesM. sabuleti about 1.5 times as long asM. ruginodis to grow from a large hibernated larva to a white pupa. 3. No large differences in larval survival or gyne production could be detected between the temperature treatments. There was an indication that most species, survived best at about 22°C. 4. The results are discussed briefly in terms of the ecological distribution of the four species in the South of England. 5. The possible effects of a fluctuating temperature regime are discussed, it is suggested that the amplitude of fluctuations may not have any great effect whereas the periodicity could be more important.
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  • 6
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    Insectes sociaux 30 (1983), S. 149-164 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Chromosomenzahlen von 40 Ameisenarten werden mitgeteilt. Für 22 Arten wird zusätzlich der Karyotyp vorgelegt. Die haploiden Chromosomenzahlen bewegen sich zwischen n=8 und n=26. Bemerkenswert sind die Karyotypen der GattungLasius. Diese Karyotypen besitzen, abgesehen von einem oder zwei mediozentrischen Paaren, ausschliesslich acrozentrische Chromosomen. Alle übrigen Karyotypen bestehen überwiegend aus medio- bzw. submediozentrischen Chromosomen. In der GattungCamponotus entspricht die Gruppierung in Untergattungen auch einer Gruppierung von unterschiedlichen Chromosomenzahlen. Für die GattungenAphœnogaster undLeptothorax gilt diese Entsprechung nicht.
    Notes: Summary The chromosome numbers of 40 ant species are reported. For 22 species the karyotypes as well as the chromosome numbers are presented. The chromosome numbers range between n=8 and n=26. Remarkable karyotypes are those of the genusLasius in exhibiting mainly acrocentric chromosomes. In all other karyotypes the majority of chromosomes show medio- or submediocentric centromere position. Differences in chromosome numbers in the genusCamponotus reflect the grouping in subgenera with the exception ofTanœmyrmex. This pattern is not true for the generaAphœnogaster andLeptothorax, where a variety of chromosome numbers were found in the different subgenera.
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  • 7
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    Insectes sociaux 30 (1983), S. 210-220 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary Density effects inEublaberus distanti have been tested upon larvæ in groups of 20, 100 and 500 individuals. Increased density leads to higher larval mortality, particularly in young larvæ, a larger difference between slow development and rapid development, and a decrease in adult size. Density effects in cockroaches can be explained in terms of population dynamics comparable to phasic modifications of desert Locusts.
    Notes: Resume Les effets de la densité ont été testés sur des lots de larves de l'espèceEublaberus distanti, lots de 20, 100 et 500 individus par 615 cm2. Lorsque la densité augmente, la mortalité larvaire s'accroit, surtout chez les larves jeunes. L'augmentation de densité accentue les différences entre individus à développement rapide et développement plus lent, de même qu'elle implique une réduction de taille chez les adultes. Les effets de la densité s'expliquent par la dynamique de la régulation des populations de Blattes, comparable aux modifications phasaires des Acridiens migrateurs.
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  • 8
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    Insectes sociaux 30 (1983), S. 235-240 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Ein Volk vonHarpagoxenus sublœvis wurde in einem naturnahen Habitat künstlich angesiedelt. Am 7. und 8. Juli 1981, zwischen 2015 und 2130 MEZ, konnte erstmalig unter Freilandbedingungen das Locksterzelverhalten ergatomorpher Jungweibchen in Nestnähe beobachtet werden. Gleichzeitig fand am 7. Juli ein Sklavenraubzug desHarpagoxenus-Volkes auf ein benachbartesLeptothorax acervorum (Fabricius)-Nest statt. Das bisher nur aus Laborbeobachtungen bekannte Sexualverhalten wird somit unter Freilandbedingungen in gleicher Form gezeigt.
    Notes: Summary A colony ofHarpagoxenus sublœvis was artificially established in a near-natural habitat. The sexual calling behavior of young ergatomorphic queens was observed for the first time under field conditions on July 7 and 8 1981, between 2015 and 2130 Central European Time. Simultaneously, on July 7, theHarpagoxenus colony conducted a slave raid on a neighboring nest ofLeptothorax acervorum (Fabricius). Previously the sexual behavior was known only from laboratory studies, these observations now show that it is performed in an identical manner under natural conditions.
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  • 9
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    Insectes sociaux 30 (1983), S. 255-258 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary The author proposes a new method of marking (with wire rings) which renders possible the individual identification of all the members of the colony.
    Notes: Resume L'auteur propose une nouvelle méthode de marquage, au moyen de ceintures de métal, permettant d'identifier chaque membre de la société.
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  • 10
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary In the antCataglyphis cursor, four categories of workers can be defined: minim, small, medium, large and very large. In each category, the workers are able to lay reproductive eggs and to produce, by parthenogenesis, queens, males and new workers of all sizes. Medium sized workers show the higher productivity. Average egg size and fecundity are related to workers size. All eggs seem able to develop. Difference between workers appear more quantitative than qualitative; the monophasic polymorphism of this species corresponds to this biological resemblance.
    Notes: Resume Chez la fourmiCataglyphis cursor, on peut définir 4 catégories d'ouvrières: minimes, petites, moyennes, grandes et très grandes. Dans chaque catégorie, les ouvrières sont capables de pondre et de produire par parthénogenèse, des reines, des mâles et de nouvelles ouvrières de toutes tailles. Les ouvrières moyennes présentent la plus forte productivité. La grosseur moyenne des œufs et la fécondité varient avec la taille des ouvrières; tous les œufs semblent capables de se développer. Les différences entre ouvrières apparaissent donc davantage comme quantitatives que qualitatives; le polymorphisme monophasique de l'espèce correspond bien à cette similitude biologique.
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  • 11
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    Insectes sociaux 25 (1978), S. 53-62 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In einigen Arten vonDrepanotermes zeigen die Arbeiter eine altersabhängige Arbeitsteilung in bezug auf Reparaturen am Nest und Sammelaktivität. Sofort nach der Beschädigung eines Nestes nahm die Anzahl der Arbeiterstadien A1, A2 und A3 ab, während die Arbeiterstadien A4+A5 und die Soldaten häufiger anzutreffen waren. Dies traf fürD. rubriceps als auch fürD. perniger zu. A4+A5 führten den grössten Anteil der Nestreparaturen aus, und zumindestens inD. perniger war die Anzahl dieses Arbeiterstadiums noch 60 Stunden nach der Beschädigung signifikant höher als in unbeschädigten Teilen des Nestes. An den oberirdisch sammelnden Termitengruppen waren inD. perniger über 75% Arbeiter des Stadiums A4+A5 beteiligt. Die Häufigkeit der jüngeren Stadien nahm stark mit absteigendem Alter ab. Soldaten waren ebenfalls überdurchschnittlich in den Sammelgruppen vertreten. In den peripheren Gallerien waren A4+A5 nicht unbedingt häufiger anzutreffen als im Inneren des Nestes, obwohl sie in den Sammelgruppen deutlich überwogen.
    Notes: Summary Species ofDrepanotermes show instar-dependent behavioural differences in the worker caste in both nest repair and foraging activity. Immediately following damage to the nest, the frequencies of W1, W2 and W3 at the damaged site decreased, while those of W4+W5 and soldiers increased in bothD. rubriceps andD. perniger. W4+W5 carried out most of the nest repair, and, at least inD. perniger, their frequency was still significantly higher at the damaged site 60 hours after damage. InD. perniger more than 75% of termites in the above-ground foraging parties were W4+W5, and the frequencies of younger workers were related to instar, the earlier the instar the lower the frequency. Soldiers were also over-represented in foraging parties. W4+W5 were not necessarily more abundant in the peripheral galleries than they were in the central nest, despite their predominance in the foraging parties.
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  • 12
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    Insectes sociaux 30 (1983), S. 57-69 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les reines du frelon oriental sont agressives l'une envers l'autre au début de la saison active, pendant les mois de mai, juin et juillet: elles défendent leur “Lebenraum” à l'intérieur du nid et ne permettent à aucune autre reine de pénétrer dans leur territoire. A cette période, toute rencontre de 2 reines, dans le nid de l'une ou dans tout autre endroit, déclenche un comportement agressif mutuel. Le combat qui s'ensuit peut durer des heures et dans son déroulement, si l'une des reines défait l'autre elle la pique au cou jusqu'à la mort. Cependant, dans de nombreux exemples, le combat n'apporte pas de solution: les combattants épuisés se retirent avant de reprendre le combat. D'autres fois, l'une des reines peut réussir à mutiler sa rivale en amputant l'extrémité de ses pattes. La reine estropiée abandonne le combat en adoptant une posture d' “infériorité” à l'égard du vainqueur et en offrant de la nourriture. Nous avons décrit en détail les différentes phases du combat entre les reines mises par deux.
    Notes: Summary Queens of the Oriental hornet are aggressive towards one another in the beginning of the active season, during the months of May, June and July: they defend their “Lebenraum” within the nest and do not enable any other queen to enter their territory. At that period any encounter between two queens, whether within the nest of the one or anawhere else, releases mutual aggressive behavior. The ensuing combat may last for hours and in its course, if the one queen beats the other, it stings it to death in the neck. In many instances, however, the combat remains unresolved and the exhausted combatants withdraw to recuperate before resuming their battle. At other times, one of the queens may succeed in maiming its rival by amputating the tips of its limbs at which point the disabled queen concedes the fight by assuming an “inferior” posture towards the victor and making a food offering. The various phases in the combat between queen pairs are described in detail.
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  • 13
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Resume Les distributions de trois «formes», en réalité des espèces jumelles d'Iridomyrmex purpureus furent étudiées près de Morgan en Australie du Sud, où la précipitation annuelle est de 230 mm. La dispersion des colonies a été décrite en détail pour une «forme bleue» et pour la formepurpureus sens. strict. qui existait dans cette région bien au-delà de ses limites pour les basses précipitations. Une colonie exceptionnellement grande d'I. purpureus couvrait un territoire de 10 ha: comprenant plus de 85 nids, elle avait plus de 1 500 entrées individuelles. Nous avons décrit les interactions entre les ouvrières des différentes formes, et leurs interactions au sein et entre les colonies de la même forme. La totalité de la faune de fourmis de la région et les faunes qui accompagnaient les différentes espèces d'Iridomyrmex furent étudiées au moyen de récoltes faites à la main et de piègeages dans des fosses. La diversité (abondance d'espèces) et la présence d'espèces de fourmis sans adaptations particulières sont liées au type de végétation et auxIridomyrmex associées. Les prises dans les pièges suggérant que le nombre d'individus et le nombre d'espèces d'autres taxons actifs à la surface du sol, en particulier les collemboles, sont affectés par le nombre de fourmis, en particulier les espèces d'Iridomyrmex et d'autres fourmis sans adaptations particulières. Au niveau évolutif, lesIridomyrmex influencent aussi la faune associé. On a noté la présence d'araignées zodariides présentant un mimétisme de couleur par rapport aux espèces presque identiques d'I. purpureus, dont ils sont des prédateurs. Nous avons noté et discuté des cas possibles de mimétisme d'I. purpureus par des fourmis du genreCamponotus.
    Notes: Summary The distributions of three “forms”, actually sibling species, of meat ant were studied near Morgan, South Australia, an area with mean annual rainfall of 230 mm. Colony dispersion is described for a “blue form” and for formpurpureus sens. strict. which occurs in this locality far beyond its normal low rainfall limit. An unusually large colony ofpurpureus had a territory covering 10 ha with more than 85 nests and over 1,500 individual nest entrances. Worker interactions between forms, and within and between colonies within forms are described. The ant fauna of the locality as a whole and the faunas accompanying differentIridomyrmex species were investigated by means of hand collections and pitfall trapping. Diversity (species — richness) and the occurrence of widely adapted ant species are related to vegetation type and associatedIridomymex. Catches of pitfall traps suggested that the numbers of individuals and species of other taxa active on the soil surface, predominantly Collembola, were affected by numbers of ants, particularlyIridomyrmex species and other, widely adapted ants.Iridomyrmex also influence associated fauna at an evolutionary level. The presence of zodariid spiders which are sibling species-specific colour mimics and predators of meat ants is noted. Possible cases of mimicry of meat ants by ants of the genusCamponotus are recorded and discussed.
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  • 14
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    Insectes sociaux 25 (1978), S. 339-350 
    ISSN: 1420-9098
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die europäische, sklavenhaltende AmeiseHarpagoxenus sublaevis weist einen speziellen Polymorphismus im weiblichen Geschlecht auf: Neben normalen Arbeiterinnen kommen zwei Formen von Königinnen vor, das normale, jedoch sehr seltene, geflügelte Weibchen und das viel häufigere arbeiterinähnliche, sogenannte ergatoide Weibchen. Für die Entwicklung von Larven entweder zu ergatoiden oder zu geflügelten Weibchen ist ein genetischer Mechanismus verantwortlich. Wir sammelten 61 Völker des nahe verwandten, nordamerikanischenHarpagoxenus canadensis an verschiedenen Orten in Ontario und Quebec, Kanada, und sezierten daraus insgesamt 241 Arbeiterinnen, 30 Intermorphe und 26 entflügelte Weibchen um festzustellen, ob ein ähnlicher Polymorphismus auch bei dieser Art vorliegt.H. canadensis hat jedoch einen recht normalen Polymorphismus. Alle Königinnen, die wir fanden, waren entflügelte Weibchen. Das receptaculum seminis, das den einzig bedeutsamen Unterschied zwischen ergatoiden Weibchen und Arbeiterinnen vonH. sublaevis darstellt, fehlt allen Arbeiterinnen und Intermorphen vonH. canadensis. Weitere Ergebnisse unserer Untersuchung sind folgende:H. canadensis ist, wieH. sublaevis, monogyn. In wenigen Kolonien legen einige Arbeiterinnen und Intermorphe Eier, auch in weiserlrichtigen Völkern. Die durchschnittliche Ovariolenzahl ist beiH. canadensis-Arbeiterinnen wesentlich geringer als beiH. sublaevis, variiert bei beiden Arten jedoch in etwa demselben Ausmß (table IV);H. canadensis-Arbeiterinnen sind darin den Arbeiterinnen der Wirtsarten ähnlicher. Die Anzahl der Malpighigefäße beträgt 5 bei Weibchen und Arbeiterinnen. Die Giftdrüse hat bei beidenHarpagoxenus-Arten etwa dieselbe Größe. Dagegen ist beiH. canadensis die Dufour-Drüse erheblich kleiner als beiH. sublaevis. H. canadensis ist damit in einer Reihe von Merkmalen der gemeinsamen WirtsgattungLeptothorax (S. G.Mychothorax) ähnlicher alsH. sublaevis.
    Notes: Summary The European slave-making antHarpagoxenus sublaevis has an unusual female polymorphism. In addition to ordinary workers, there are two kinds of reproductive females, the very rare full queens and the much more common ergatoid (i. e. workerlike) queens. A genetic mechanism is responsible for the development of larvae into either ergatoid or full queens. Sixty-one colonies of the closely related North American speciesHarpagotenus canadensis were collected from several localities in the provinces of Ontario and Quebec, Canada, and a total of 241 workers, 30 intermorphs, and 26 dealate full queens were dissected in order to discover whether a similar polymorphism occurs in this species. However,H. canadensis was found to have an essentialy normal polymorphism. All the fecundated reproductive females that we found were dealate full queens. A spermatheca, which constitutes the only significant difference between ergatoid queens and workers inH. sublaevis, is absent in all workers and intermorphs ofH. canadensis. In addition, we found that colonies ofH. canadensis are monogynous (likeH. sublaevis). However, minority of workers and intermorphs lay eggs even in queenright colonies. The average number of ovarioles is much lower inH. canadansis workers than in those ofH. sublaevis; but, in both species, it varies over about the same range (table IV). In this respect,H. canadensis workers resemble more closely the workers of the host species. The number of Malpighian tubules is five in both the reproductive females and workers. The poison gland is about the same size in bothHarpagoxenus species, but the Dufour's gland inH. canadensis is considerably smaller than inH. sublaevis. Thus, in several respects,H. canadensis bears a closer resemblance to the common host genusLeptothorax (subgenusMychothorax) thanH. sublaevis does.
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  • 15
    ISSN: 1420-9136
    Keywords: Condensation nuclei ; Aerosol particles ; -water uptake of ; -growth of
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Equilibrium water uptake and the sizes of atmospheric aerosol particles have for the first time been determined for high relative humidities, i.e., for humidities above 95 percent, as a function of the particles chemical composition. For that purpose a new treatment of the osmotic coefficient has been developed and experimentally confirmed. It is shown that the equilibrium water uptake and the equilibrium sizes of atmospheric aerosol particles at large relative humidities are significantly dependent on their chemical composition.
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    Pure and applied geophysics 116 (1978), S. 159-166 
    ISSN: 1420-9136
    Keywords: Ionization of moist air ; of dry air ; Coefficient for a water surface
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    Topics: Geosciences , Physics
    Notes: Summary A comparison has been made between the Townsend primary ionization coefficient, α, for dry air and for air with humidities typical of those in the atmosphere. α is defined as the number of new electrons produced by an electron per centimeter of drift in a field. A range of field/pressure ratios,E/p 0, of 40 to 100 V (cm torr)−1 was employed. The variation of α with humidity is very small. Over the range ofE/p 0 from 50 to 100 V (cm torr)−1, the secondary ionization coefficient, γ, of a water surface has been found from sparking potential data to be typically 2×10−4. γ represents the fraction of primary ionizing collisions that ultimately result in the production of additional electrons at the surface.
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    Pure and applied geophysics 116 (1978), S. 302-308 
    ISSN: 1420-9136
    Keywords: Bacteria ; Bubbles ; Scavenging
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    Topics: Geosciences , Physics
    Notes: Abstract Four parameters that control the enrichment of bacteria in jet drops are bubble scavenging, drop size, drop position in the jet set, and the type of bacteria. Without the scavenging of bacteria as a bubble rises through the water it is doubtful that the observed enrichment factors, EF, greater than 1000 could be obtained. There is a maximum in EF as a function of top jet drop size, and the EF decreases from the top to the bottom drop of the jet set. The efficiency by which bubbles scavenge bacteria varies with species. Presumably these parameters apply in some degree to the EF of virus in jet drops. Dissolved organic material in natural waters can adsorb to bubbles and contribute to a large EF in jet drops, but there is a feedback mechanism whereby changes in bubble surface free energy modify the jet drop-size distribution. However, there is reason to believe this will not significantly influence the jet drop-size distribution produced by bubbles in the sea.
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    Pure and applied geophysics 116 (1978), S. 372-384 
    ISSN: 1420-9136
    Keywords: Atmospheric Hydrocarbons ; Air Chemistry ; Hydrocarbon concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Trace concentrations of highly reactive hydrocarbons of biogenic origin have been proposed for some time as being important in aerosol formation processes in the atmosphere. More recently, assessments of potential photochemical reactions in the troposphere have proposed a role in the atmospheric ozone cycle for hydrocarbons, even for compounds such as methane that had previously been considered nonreactive. An assessment of the atmospheric hydrocarbon reaction system has been limited by a lack of observational information on the nature of conditions in the remote or non-urban atmosphere. Recent data on terpene concentrations and other biogenic hydrocarbon compounds are presented. Data on ethane and acetylene from aircraft samples taken over the north and south Pacific Ocean show concentrations in the 0.5 to 1 μ/m3 range for ethane and in the 0.05 to 0.3 μg/m3 range for acetylene. A concentration gradient is present for these compounds between the northern and southern hemisphere. A rudimentary global concentration pattern for these C2 compounds has been developed on the basis of recent data.
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    Pure and applied geophysics 116 (1978), S. 575-582 
    ISSN: 1420-9136
    Keywords: Chlorofluoromethanes ; Stratospheric chlorine ; Oceanographic tracers
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    Topics: Geosciences , Physics
    Notes: Abstract Depth profiles of the chlorofluoromethanes (CFM), CFCl3 and CF2Cl2, have been obtained together with tritium profiles from water samples collected in the Norwegian Sea between surface and 2800 m depth. CFM analysis was performed by vacuum extraction of the dissolved gases from 500 ml samples of seawater and subsequent gaschromatographic measurement. The CFM concentration decreases with depth to about 10 percent of surface concentration at depths below 2000 m. The same behaviour is found for the tritium content. From a correlation of the CFM and tritium concentration the upper limit of the preindustrial atmospheric CFM levels can be estimated to ≤5 percent of the present day concentrations.
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    Pure and applied geophysics 116 (1978), S. 634-654 
    ISSN: 1420-9136
    Keywords: Strength of rocks ; Crack growth with water ; Rock mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A series of stress relaxation experiments have been carried out on faulted and intact Tennessee sandstone to explore the influence of pore water on strength at different strain rates. Temperatures employed were 20, 300 and 400°C, effective confining pressure was 1.5 kb and strain rates as low as 10−10 sec−1 were achieved. Most samples were prefaulted at 2.5 kb confining pressure and room temperature. This is thought to have secured a reproducible initial microstructure. The strength of the dry rock was almost totally insensitive to strain rate in the range 10−4 to 10−10 sec−1. In contrast, the strength of the wet rock decreased rapidly with strain rate at rates less than 10−6 sec−1. Brittle fracture of the quartz grains which constitute this rock is the most characteristic mode of failure under the test conditions used. The experimental data are discussed in terms of the possible deformation rate controlling processes, and it is suggested that in the wet experiments at intermediate to high strain rates (10−7 to 10−4 sec−1) the observed deformation rate is controlled by the kinetics of water assisted stress corrosion, whilst deformation at low strain rates (ca. 10−9 sec−1) is controlled by a pressure solution process. The results have implications for the rheology of fault rocks at depths of perhaps 10 to 15 km in sialic crust.
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    Pure and applied geophysics 116 (1978), S. 511-529 
    ISSN: 1420-9136
    Keywords: Ozone ; photochemistry ; transport ; vertical distribution
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    Topics: Geosciences , Physics
    Notes: Abstract All available data of the vertical ozone distribution measured with chemical sondes have been assembled and combined with one year's results from the BUV satellite to obtain the best possible information on the vertical ozone distribution averaged over longitude as a function of season (month by month). For the southern hemisphere Umkehr data have been used as a guideline in the necessary smoothing procedure. Especially in the northern hemisphere considerable adaptation to the observed latitudinal mean of the total amount was needed because most sounding stations, are situated in upper air trough positions. The results are presented as vertical distributions, as meridional cross sections of partial pressure and of mixing ratio and as partial pressure isolines as a function of latitude and season at different levels. The interaction between photochemical processes and transport resonsible for the observed distribution is briefly discussed.
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    Pure and applied geophysics 116 (1978), S. 586-602 
    ISSN: 1420-9136
    Keywords: Rock mechanics ; Earthquake prediction
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    Topics: Geosciences , Physics
    Notes: Abstract Premonitory phenomena such as dilatancy, creep, acoustic emission, and changes in seismic velocity and attenuation, electrical resistivity, magnetic moment, and gas emission, which occur before fracture of initially intact rock and before stick-slip on faults or between finely ground surfaces of rock, have been reviewed and discussed in relation to earthquake prediction. This review is restricted to the results of laboratory experiments that have been carried out in the United States of America.
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    Pure and applied geophysics 116 (1978), S. 866-872 
    ISSN: 1420-9136
    Keywords: Fracture energy ; Identation of minerals ; Rock mechanics
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    Topics: Geosciences , Physics
    Notes: Abstract A relatively simple indentation technique for the rapid measurement of fracture surface energy, Γ, of small samples is described. The reliability of this technique is assessed by testing soda-lime glass for which there are good independent fracture mechanics determinations of fracture surface energy. The indentation technique gives a value for Γ of 4.33 J m−2 which compares favourably with the accepted value of 3.8 J m−2. Fracture surface energies of the {010} and {001} cleavage planes of single crystal olivine (modal composition Fo88Fa12) are then determined and compared with theoretical estimates of the thermodynamic surface energy, γ, calculated from atomistic parameters (γ is equal to Γ in the absence of dissipative processes during crack extension). The experimental values for Г{010} and Г{001} are respectively 0.98 J m−2 and 1.26 J m−2. The calculated values of γ{010} and γ{001} are respectively in the range from 0.37 J m−2 to 8.63 J m−2 and 12.06 J m−2. The particular advantages of the indentation technique for the study of the fracture surface energies of geological materials are outlined.
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    Pure and applied geophysics 116 (1978), S. 765-772 
    ISSN: 1420-9136
    Keywords: Velocity anomalies ; Microfractures ; Stick-slip
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    Topics: Geosciences , Physics
    Notes: Abstract Locations and velocities were calculated for microseisms occurring in samples of rock subjected to triaxial loading and injection of pore fluid. This was accomplished by analyzing arrival times of acoustic emission using an automatic first arrival picker. Apparent velocity anomalies were observed prior to both failure of intact samples and violent slip in samples containing saw cuts. Further analysis revealed that these fluctuations in calculated velocity were not due to changes in the true seismie velocity. Instead, variations in calculated velocity are shown to be related to sampling errors in picking first arrivals. The systematic picking of late first arrivals for small magnitude events was found to be a persistent bias resulting in low calculated velocities. This has encouraged the reexamination of earthquake records to determine how important sampling biases are in contributing to reported velocity anomalies.
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    Pure and applied geophysics 116 (1978), S. 732-742 
    ISSN: 1420-9136
    Keywords: Velocity changes ; Fracture ; Friction ; Holography
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    Topics: Geosciences , Physics
    Notes: Abstract Fracture and frictional sliding are considered as phenomena involving brittle failure. Brittle failure is preceded by the formation of small (subcritical) cracks. In non-water-saturated rock, the distribution, shape and size of these suberitical cracks determine the change in the physical properties prior to failure. A model is proposed which suggests that the spatial and temporal distribution, shape and size of subcritical cracks within a stressed rock depend upon the rate of deformation and the volatile content. As a rock is stressed beyond about 50 percent of its ultimate failure stress, dilatancy is initiated. With increasing stress a broad zone of cracks develops within the dilatant region. The seismic velocities through this zone decrease markedly and the cracks grow more numerous., changing in size and shape. Before brittle failure of the rock occurs, the subcritical cracks interact, leading to a concentration of the zone. During the stage when the zone narrows, the seismic velocities in crease in the surrounding volume due to local rotation of stresses and consequent closure of some cracks. In most laboratory experiments the stage during which the velocity increases and the now intense deformation zone becomes narrow is very short and difficult to observe experimentally. At very low strain rates and with volatiles present, the crack growth and subsequent interaction lead to the narrowing of the intense deformation zone and therefore to an observable increase in velocity. The above is based upon an interpretation of a number of experiments. Using optical holography we have observed the development and subsequent intensification of a deformation zone. Ultrasonic velocity measurements showed a distinct anomaly (decrease followed by an increase) before failure. The anomaly was only detectable at our lowest experimental strain rates (3×10−8/sec).
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    Pure and applied geophysics 116 (1978), S. 807-839 
    ISSN: 1420-9136
    Keywords: Creep transient ; Semi brittle rocks ; Earthquake faulting
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    Topics: Geosciences , Physics
    Notes: Abstract We review transient creep and semibrittle behavior of crystalline solids. The results are expected to be pertinent to crystalline rocks undergoing deformation in the depth range 5 to 20 km, corresponding to depths of focus of many major earthquakes. Transient creep data for crystalline rocks at elevated temperatures are analyzed but are poorly understood because of lack of information on the deformation processes which, at low to moderate pressure, are likely to be semibrittle in nature. Activation energies for transient creep at high effective confining pressure are much higher than those found for atmospheric pressure tests in which thermally-activated microfracturing probably dominates the creep rate. Empirical transient creep equations are extrapolated at 200° to 600°C, stresses from 0.1 to 1.0 kbar, to times ranging from 3.17×102 to 3.17×108 years. At the higher temperatures, appreciable transient creep strains may take place but the physical significance of the results is in question because the flow mechanisms have not been determined. The purpose of this paper is to stimulate careful research on this important topic.
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    Pure and applied geophysics 116 (1978), S. 873-887 
    ISSN: 1420-9136
    Keywords: Stiffness ; Stick-slip ; Rock-mechanics
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    Topics: Geosciences , Physics
    Notes: Summary This paper discusses the influence of system stiffness on the dynamic instability of fault surfaces under laboratory conditions for a number of test modes. In conjunction with shear load stiffness, the normal load stiffness, often neglected, is shown to have a considerable effect on the stick-slip process —its presence or absence and its characteristics. Also appropriate stiffnesses are suggested for an earthquake sequence modeled as a growing dislocation.
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    Pure and applied geophysics 116 (1978), S. 913-930 
    ISSN: 1420-9136
    Keywords: Fault structures ; Deformation bands ; Entrada and Navajo Sandstores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Small faults with displacements of a few millimeters or centimeters are abundant in the Entrada and Navajo Sandstones, in the San Rafael Desert, Utah, where they are important primary structures, preceding the development of large faults with displacements of several meters or tens of meters. The small faults contain no surfaces of discontinuity, rather they occur asdeformation bands about one millimeter and tens or hundreds of meters long, and across which the displacements are distributed. Two zones with different modes of deformation can be distinguished within a deformation band: an outer zone where the matrix, including pores and matrix material, deforms; and an inner zone, about 0.5 mm thick, where the sand grains fracture and further consolidation takes place. Fracturing of the grains is controlled by contact geometry; the grains tend to split into subgrains along lines connecting contact points between the grains. Then the angular subgrains, which are readily fractured, are further granulated and mixed with the matrix. The final product is the deformation band, with much smaller grain size, poorer sorting, and lower porosity than the original parent sandstone. The sandstone on either side of a deformation band is almost undisturbed-fractures are rare there — so that deformation is highly localized within the band. The material within a deformation band apparently strain hardens as a result of the deformation; perhaps this is why the shear displacement across a deformation band is at most a few centimeters.
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  • 29
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    Pure and applied geophysics 116 (1978), S. 954-963 
    ISSN: 1420-9136
    Keywords: Friction ; Rupture and Particle velocity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary Laboratory measurements of rupture and particle velocity are in surprisingly good agreement with seismic values, providing further evidence that stick-slip friction is a suitable mechanism for shallow earthquakes. A simple theory is developed to explain the linear relationship observed between average particle velocity and stress drop for stick-slip events. Both stick-slip ruptures and cracks in brittle material commonly propagate at velocities roughly comparable to theS wave velocity of the material. Rupture normally begins relatively slowly and accelerates to a steady velocity in a few centimeters. Observations suggest that stick-slip ruptures can propagate atS wave speeds or occasionally greater and that cracks in pre-stressed glass can also propagate faster than theS waves. Fracture and thus rupture velocity of intact rock specimens is greatly influenced by the inhomogeneous structure of rock. Fracture may be modeled by coalescence of many cracks rather than growth of a single crack.
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    Pure and applied geophysics 116 (1978), S. 964-989 
    ISSN: 1420-9136
    Keywords: Friction ; Earthquake mechanics
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    Topics: Geosciences , Physics
    Notes: Abstract A review of simple models and observations suggests that the main first-order features of active faulting-mechanical instability, the frequency-magnitude relations, seismic and aseismie slip, seismic radiation, incoherency and rupture stoppage — may be explained by a single characteristic of crustal faults: the spatial variation of the effective frictional stress, which resists slippage on faults. Faultoffset data suggest that rupture propagation ceases in regions of high resistance which act, as barriers. In these regions slippage is associated with negative stress drop. The spacing λ and the amplitudeA(λ) of the barriers, as inferred from the frequency-magnitude and moment relation for earthquakes, obeys a simple statistical relationA(λ)∼λp. On the scale of particle motion, this variability of frictional stress provides a mechanical instability which may be associated with the concept of dynamic friction. Invariably, the rapid particle motion in the model is always preceded by accelerated creep. The particle acceleration is highly irregular, giving rise to an almost random acceleration record on the fault. The particle displacement is relatively smooth, giving rise to simple displacement time function in the far field. Rupture propagation time is approximately proportional to the gradient of frictional stress along the fault. Consequently sharp changes of this stress may cause multiple events and other long period irregularities in the fault motion. The power density spectrum associated with the frictional stress implies that stress may be related to a Poisson distribution of lengths. The autocorrelation of such type of distribution yields a correlation lengthk L −1 , similar perhaps toHaskell's (1964) andAki's (1967) correlation lengths inferred from spectral analysis of seismic waves. The partial incoherency of faulting implies that preseismic deformation may be significantly incoherent, consequently the prediction of small moderate earthquakes may be subject to inherent uncertainties. We conclude that frictional stress heterogeneities may be necessary and sufficient to explain active faulting associated with small and moderate earthquakes.
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    ISSN: 1420-9136
    Keywords: satellite meteorology ; Cirrus clouds ; Radiative transfer through cirrus
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    Topics: Geosciences , Physics
    Notes: Abstract A one-dimensional spectral infrared radiative transfer model has been developed for atmospheres containing cirrus clouds and absorbing gases above, below and within the cloud. The transfer model takes into consideration the inhomogeneity of the cloudy atmosphere, the gaseous absorption in scattering cloud layers and the wavenumber dependence of radiative transfer. In addition, the cirrus cloud is further divided into a number of sub-layers to account for the non-isothermal and inhomogeneous cloud characteristics. Single-scattering properties for ice crystals are calculated assuming ice cylinders 200 and 60 μm in lenght and width, respectively, randomly oriented in a horizontal plane. The spectral infrared transfer program is applied to VTPR channels of the NOAA 4 satellite to simulate upward radiances in cirrus cloud conditions. Comparisons between satellite observed and theoretically simulated upward radiances are carried out for selected cirrus cloud cases. Incorporating atmospheric profiles obtained from radiosonde and the observed cloud information into the spectral transfer program, we show a systematic agreement between observed and computed upward radiances. Systematic reduction patterns of the upward radiance caused by the increase of the cloud ice content are clearly demonstrated for VTPR channels employing tropical and midlatitude atmospheric profiles. Having the quantitative relationships between upward radiances and ice contents, procedures are described for the inference of the cloud ice content and cloud amount. The proposed method has been successfully applied to the three cirrus cloud cases.
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    Pure and applied geophysics 116 (1978), S. 1089-1100 
    ISSN: 1420-9136
    Keywords: Atmospheric electric field
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    Topics: Geosciences , Physics
    Notes: Abstract Fluctuations of short period in the atmospheric electric field were studied through the measurements of electric field and space charge density on the Mid-Pacific Ocean. The amplitude of fluctuation is about one third of the mean electric field, and the period mainly ranges from 2 to 5 min. The fluctuations are considered to be under the influence of spatial and temporal variation of space charge layer that possibly originates from the electrode effect above the sea surface. The unit of electrical irregularities in the atmosphere above the ocean has horizontal scale of the order of 1.5 km and indicates a tendency to become large as the wind speed increases. The vertical scale of space charge layer is estimated at several tens meters.
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    Pure and applied geophysics 116 (1978), S. 1118-1142 
    ISSN: 1420-9136
    Keywords: Electromagnetic waves ; transmission of in troposphere ; Microwaves ; transmission of in troposphere
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    Topics: Geosciences , Physics
    Notes: Summary Theory for the transmission of electromagnetic waves in a non-uniform troposphere is presented. The atmospheric refractive index is allowed to vary both with height and range. The formulation is facilitated by the fact that the field within a piecewise (laterally) uniform section can be represented by a discrete sum of modes that are orthogonal in the transverse plane. Using the appropriate radial wave functions, mode conversion at a junction between two laterally uniform sections is considered. The analysis is then extended to multi-section structures. A few typical profiles of refractive index are examined numerically for both uniform and non-uniform models. One of the important findings is that the lateral non-uniformities in an elevated duct will enhance the overall transmission for ground-based transmitting and receiving antennas.
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    Pure and applied geophysics 116 (1978), S. 1231-1249 
    ISSN: 1420-9136
    Keywords: Plate tectonics ; Lithosphere ; Asthenosphere ; Convection ; Mantle flow ; Viscosity of the mantle
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    Notes: Abstract A one-dimensional model of flow between a fixed boundary at the bottom and a moving one on top with no net flow through vertical sections is tested for geophysically interesting mantle viscosity-depth functions. Such a model, although simplistic, may help in answering the question to what depth the return flow extends, at least in the case of moving plates measuring many thousand kilometers across, such as the Pacific plate. It the viscosity in the asthenosphere is less than three orders of magnitude smaller than that of the mantle below, the return flow extends to great depth and the asthenosphere is a zone of concentrated shear. If the viscosity contrast is greater, the return flow is concentrated in the asthenosphere. For a wide range of model parameters typical flow velocities below the asthenosphere are about one-tenth of the plate velocity. The pressure gradient required by the mantle flow may be manifest in gravity trends across moving plates, but no excessive gravity anomalies are required by the model if the absolute viscosity values conform to those inferred from post-glacial rebound data. A thinner and lower-viscosity layer is favored over a thicker and more viscous layer if both fit glacial rebound evidence. The present model may not be applicable if down to the core the viscosity is as low as about 1021 N s m−2 with a free-slip bottom boundary.
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    Pure and applied geophysics 117 (1978), S. 1-2 
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    Pure and applied geophysics 117 (1978), S. 361-366 
    ISSN: 1420-9136
    Keywords: Aerosol effects ; Dobson spectrophotometer ; Total ozone
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    Notes: Abstract The effect of aerosol extinction on Dobson measurements of total ozone is investigated, and several recent attempts to resolve this problem are reviewed. It is pointed out that the balloon measurements of Paetzold and his colleagues circumvent this problem: Solar-cycle and quasi-biennial effects can be clearly discerned in the balloon data. It is suggested that Paetzold's data would be ideal for testing stratospheric models and searching for man's effect on the stratospheric ozone layer.
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    Pure and applied geophysics 117 (1978), S. 367-380 
    ISSN: 1420-9136
    Keywords: Stratosphere ; Methane
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    Notes: Abstract A new determination of stratospheric methane from 22 km to 35 km altitude with implications on the abundance of this constituent at greater heights is presented. Previous measurements, some of which showed large discrepancies with currently admitted values, have been reinterpreted and brought into agreement. The results are in contradiction according to present theories with thein situ determined CH4 abundances at the upper edge of the stratosphere. Implications on the vertical transport coefficient used in one dimensional models are discussed.
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    Pure and applied geophysics 117 (1978), S. 381-394 
    ISSN: 1420-9136
    Keywords: Grille spectrometer ; Infrared absorption spectrometry ; Stratospheric trace constituents
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    Topics: Geosciences , Physics
    Notes: Summary Spectrometric experiments performed, in November 1976, within the framework of the ‘Latitude Survey Mission’ on board the NASA Convair 990 from Ames Research Center are briefly deseribed. The results presented concern odd nitrogen molecules, HCl and water vapor. In terms of vertical column density, HNO3 is predominant over NO+NO2 at all latitudes higher than 40 degrees. A seasonal variation of NO2 abundance is observed, with larger values in the summer hemisphere at high latitude. The mean zenith column density of HCl above 11 km is 1.5×1015 mol.cm−2, with no evidence for any seasonal or climatic variation. Local number densities as high as 1.4×1010 mol.cm−3 for HNO3 and 5.4×1014 mol.cm−3 for water vapor have been measured during the same flight near 11 km.
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    Pure and applied geophysics 117 (1978), S. 531-536 
    ISSN: 1420-9136
    Keywords: Chlorofluoromethane ; Infrared spectra
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    Topics: Geosciences , Physics
    Notes: Abstract Laboratory infrared absorption spectral measurements of CF2Cl2 in the 10.8 μm band have been performed. Doppler limited resolution has been achieved using semiconductor tunable lasers. The line strength and the self and pressure broadening rates have been measured for the 918.562 and 918.621 cm−1 lines. The results are used for considerations on the application of high resolution spectroscopy to the measurement of atmospheric CF2Cl2.
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  • 40
    ISSN: 1420-9136
    Keywords: Hail prevention ; Randomized seeding ; Statistical design
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    Topics: Geosciences , Physics
    Notes: Abstract An experimental research program is described which investigates the possibility of reducing hailfall in an area of 1000 km2 using the Moldavian rocket seeding method. It involves a design in which experiments are randomized (50∶50) by day over a fixed experimental area. The evaluation is based on data collected during the experimental unit (12–2100 hours). The test variable is hail kinetic energy measured by hailpads and by a hailpad-adjusted S-band radar. A description of the experimental area, the instrumentation and the seeding method adapted from the Soviet Union as well as calculations of the nuclei plume behaviour after seeding with large Oblako rockets are presented. The statistical design is given as well as an extensivea priori description of the confirmatory evaluation procedure which will be used to prove an eventual seeding effect. It is recognized that good predictors are essential to arrive at a statistically significant results in 5 years. From synoptic and radar data obtained during the preliminary phase of the experiment a predictor function is derived. A concomitant variable (cloud base temperature) is proposed taking into account a possibly variable reaction of different storm types to the seeding. The development of the statistical test to be used is also described. Section 7 indicates some possibilities for further exploratory analyses with emphasis on hailpad measurements.
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  • 41
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    Pure and applied geophysics 117 (1978), S. 599-626 
    ISSN: 1420-9136
    Keywords: Drop breakup ; Drop size distribution ; Rain drops ; Drop collision
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    Topics: Geosciences , Physics
    Notes: Abstract New equations and techniques for dealing with drop breakups are developed and applied to the modelling of the evolution of raindrop spectra in rainshafts. Breakup experiments byMcTaggart-Cowan andList (1975) served as data base. No matter what the original size distribution, the spectrum evolution will always lead to a Marshall-Palmer type equilibrium di tributionN=N 0e−ΛD, with Λ=constant andN 0 proportional to the rainfall rateR. (D stands for raindrop diameter.) ForR≥29 mm h−1 and an original Marshall-Palmer distribution, the required fall height to reach equilibrium is ≲2 km. The equilibrium distributions are characterized by linear relationships betweenR, the radar reflectivity factorZ, the liquid water content LWC and theN 0 of the Marshall-Palmer distribution. Possible explanations for the discrepancy with observations are given. The fact that the all-water processes cannot produce drops withD≥2.5 mm (as confirmed by observations) leads to the conclusion that observed large raindrops withD≈5 mm represent melted hailstones and have not yet reached an equilibrium distribution. These latter conclusions were reached within the original assumption of videspread, steady state precipitation.
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  • 42
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    Pure and applied geophysics 117 (1978), S. 711-742 
    ISSN: 1420-9136
    Keywords: Resistivity ; Conductors in earth ; Buried Cables ; Direct Current
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    Topics: Geosciences , Physics
    Notes: Abstract Current flow in homogeneous and layered conducting media is analyzed for the case where an axial conductor or cable is present. The cable is characterized by a specified axial impedance and is assumed to be infinite in length. Various configurations are chosen such as a current point source in an infinite, semi-infinite, and layered region where the cable is taken parallel to the interface(s). The resulting formulas for the potentials reduce to known cases in the absence of the cable. Using these formulations, we present some concrete calculated examples that are relevant to resistivity probing of perturbed homogeneous and layered structures. Only the two-electrode array is treated, but various cable orientations are considered. In general, it is found that a long axial conductor such as a bare cable will distort the potential distribution of the current in a major way. This leads to profound departures from the apparent resistivity curves calculated for idealized homogeneous and layered structures.
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  • 43
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    Pure and applied geophysics 117 (1978), S. 253-261 
    ISSN: 1420-9136
    Keywords: Radon concentrations of steam ; Radon emanating power of rocks ; Flow rate of producing wells ; Steam reservoirs ; Fluid transit time ; Larderello, Italy
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    Topics: Geosciences , Physics
    Notes: Abstract The authors conducted a Rn222 survey in wells of the Larderello geothermal field (Italy) and observed considerable variations in concentrations. Simple models show that flow-rate plays an important part in the Rn222 content of each well, as it directly affects the fluid transit time in the reservoirs. Rn222 has been sampled from two wells of the Serrazzano area during flow-rate drawdown tests. The apparent volume of the steam reservoir of each of these two wells has been estimated from the Rn222 concentration versus flow-rate curves.
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  • 44
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    Pure and applied geophysics 117 (1978), S. 276-289 
    ISSN: 1420-9136
    Keywords: H2S, CO2, N2, H2, Hydrocarbon gases ; Oxygen isotopes ; Deuterium content of steam ; Isotope exchange ; Thermal metamorphism ; Rock-water reactions
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    Topics: Geosciences , Physics
    Notes: Abstract Steam samples from six wells (Colombaia, Pineta, Larderello 57, Larderello 155, Gabbro 6, and Gabbro 1) in a south to north section across the Larderello geothermal field have been analyzed for inorganic and hydrocarbon gases and for oxygen-18 and deuterium of steam. The wells generally decrease in depth and increase in age toward the south. The steam samples are generally characterized by (1) Total gas contents increasing south to north from 0.003 to 0.05 mole fraction; (2) Constant CO2 (95±2 percent); near constant H2S (1.6±0.8), N2 (1.2±0.8), H2 (2±1), CH4 (1.2±1), and no O2 in the dry gas; (3) Presence of numerous, straight chain and branched C2 to C6 hydrocarbons plus benzene in amounts independent of CH4 contents with highest concentrations in the deeper wells; (4) Oxygen-18 contents of steam increasing south to north from −5.0‰ to −0.4‰ with little change in deuterium (−42±2‰). These observations are interpreted as showing: (1) Decreasing gas contents with amount of production because the proportion of steam boiled from liquid water increases with production; (2) Synthesis of CH4 from H2 and CO2 with CO2 and H2 produced by thermal metamorphism and rock-water reactions; (3) Extraction of C2 to C6 hydrocarbons from rock organic matter; (4) Either oxygen isotope exchange followed by distillation of steam from the north toward the south (2 plates at ∼220°C) or mixture of deeper more-exchange waters from the north with shallow, less-exchanged recharging waters from the south.
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  • 45
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    Pure and applied geophysics 117 (1978), S. 309-320 
    ISSN: 1420-9136
    Keywords: Flow of hot water ; Vertical fault ; Finite difference method ; Buoyant flow ; Two-dimensional temperature field
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    Topics: Geosciences , Physics
    Notes: Abstract Many geothermal anomalies are intersected by vertical fault zones (narrow zones of fractured material with large effective permeability). These conduits are probably responsible for much of the upwelling of hot water from depth. This paper considers a shallow aquifer intersected by a vertical fault. The fluid flow in the aquifer is numerically modeled as a two-dimensional problem. It is observed that the temperature distribution in the aquifer is governed primarily by lateral flow of hot water supplied from the intersecting vertical fault and only secondarily by conduction. The numerical results also provide a possible explanation for the local temperature maxima and inversions occasionally observed in borehole measurements. The present model is an alternative to that based on mushroom-shaped isotherm distributions found in high Rayleigh number large-scale circulation cell calculations.
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  • 46
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    Pure and applied geophysics 117 (1978), S. 436-447 
    ISSN: 1420-9136
    Keywords: Chlorofluoromethanes ; Ozone photochemistry ; Two dimensional model
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    Topics: Geosciences , Physics
    Notes: Abstract In order to study the behavior of stratospheric minor constituents related to aeronomic processes and atmospheric transport in the meridional plane, a numerical two-dimensional model is established. This model is applied to the study of chlorine compounds in the stratosphere. A special attention is devoted to the effect in the ozonosphere of an increase of CIX due to anthropogenic activities.
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  • 47
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    Pure and applied geophysics 117 (1978), S. 513-530 
    ISSN: 1420-9136
    Keywords: Stratosphere ; Troposphere ; Turbulent diffusion
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    Notes: Abstract A generalized turbulent diffusion model has been developed which evaluates the time rate of growth of a simulated ‘cloud’ of particles released into a turbulent (i.e. diffusive) atmosphere. The general model, in the form of second-order differential equations, computes the three-dimensional size of the cloud as a function of time. Parameters which influence the cloud growth, and which are accounted for in the model equations, are: (1) length scales and velocity magnitudes of the diffusive field, (2) rate of viscous dissipation ε, (3) vertical stability as characterized by the relative adiabatic lapse rate (1/T)(g/C p +∂T/∂z), and (4) vertical shear in the mean horizontal winds $${{\partial \bar U} \mathord{\left/ {\vphantom {{\partial \bar U} {\partial z}}} \right. \kern-\nulldelimiterspace} {\partial z}}$$ , and $${{\partial \bar V} \mathord{\left/ {\vphantom {{\partial \bar V} {\partial z}}} \right. \kern-\nulldelimiterspace} {\partial z}}$$ , for a given height and of spatial extent equal to that of the diffusing cloud. Sample results for near ground level and for upper stratospheric heights are given. For the atmospheric boundary layer case, the diffusive field is microscale turbulence. In the upper stratospheric case it is considered to be a field of highly interactive and dispersive gravity waves.
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  • 48
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    Pure and applied geophysics 117 (1978), S. 486-497 
    ISSN: 1420-9136
    Keywords: Minor constituents ; Ozone ; Volcanic influence
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    Topics: Geosciences , Physics
    Notes: Abstract Although stratosphere penetrating volcanic eruptions have been infrequent during the last half century, periods have existed in the last several hundred years when such eruptions were significantly more frequent. Several mechanisms exist for these injections to affect stratospheric minor constitutent chemistry, both on the long-term average and for short-term perturbations. These mechanisms are reviewed and, because of the sensitivity of current models of stratospheric ozone to chlorine perturbations, quantitative estimates are made of chlorine injection rates. It is found that, if chlorine makes up as much as 0.5 to 1% of the gases released and if the total gases released are about the same magnitude as the fine ash, then a major stratosphere penetrating eruption could deplete the ozone column by several percent. The estimate for the Agung eruption of 1963 is just under 1% an amount not excluded by the ozone record but complicated by the peak in atmospheric nuclear explosions at about the same time. The long-term contribution to stratospheric CIX by volcanic eruptions is estimated as ∼0.1 ppbv for the period 1900–60 and ∼1 ppbv for the much more volcanically active period 1780–1840. All of the estimates are subject to large uncertainties, perhaps a factor of 2 or 3 on the high side and a factor of 10 or more on the low side.
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    Pure and applied geophysics 117 (1978), S. 573-582 
    ISSN: 1420-9136
    Keywords: Precipitable water ; Water vapour
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    Topics: Geosciences , Physics
    Notes: Abstract For the site of the astronomical observatory operated by The University of Tromsø in Skibotn, Northern Norway, the distribution of very small amounts of atmospheric water vapour is estimated from aerological data. For 5 winter months through a period of 11 years, during at least 6 per cent of the time, the precipitable water is likely not to exceed 3.0 mm, i.e. observations at wavelengths as long as 25 μ and a little short of 1 mm are possible. For a mountain site at 1250 m altitude, the corresponding amount is estimated to be 1.8 mm. The small amounts considered, were observed in the subsidence of tropospheric ridges. The Skibotn site is compared with other sites for infrared measurements in the Subtropics and in the Arctic.
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    Pure and applied geophysics 117 (1978), S. 627-663 
    ISSN: 1420-9136
    Keywords: Gravity waves ; Tropospheric dynamics
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    Topics: Geosciences , Physics
    Notes: Summary The nature and the role of gravity waves in the troposphere is briefly discussed and reviewed. After describing some basic properties of gravity waves and their generation mechanisms, we analyze their ability to influence phase changes, trigger and organize convective cells, to produce and interact with turbulence, and to affect diffusive processes in the atmosphere. Throughout, the emphasis is placed on the physical processes involved in the interaction of gravity waves with mesoscale and planetary boundary layer phenomena. Also discussed and reviewed are those remote sensing devices which are particularly useful in revealing and measuring such waves. Finally, an attempt is made to outline possible lines of future work for the purpose of fully understanding the role of gravity waves in mesoscale and microscale dynamics.
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    Pure and applied geophysics 117 (1978), S. 690-710 
    ISSN: 1420-9136
    Keywords: Electrical conductivity ; Porosity in rocks ; Pore fluids
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    Topics: Geosciences , Physics
    Notes: Abstract Calculations on the basis of the self-consistent approximation are used to study the effects of randomly distributed elliptical cracks and of non-randomly distributed circular cracks, either dry or saturated by a highly conductive material phase, on the electric conductivities of a cracked body. Analytic and numeric results are given for two special non-random distributions. In the first, the cracks are assumed randomly distributed in planes parallel to a given plane. In the second, the crack normals are randomly distributed in parallel planes. The results of the theoretical calculations indicate that the magnitudes of the crack induced variations of the dry cracked rock depend upon a crack density parameter ɛ rather than upon the crack porosity. Here, ɛ is defined as $$\varepsilon = \frac{{2N}}{\pi }〈 \frac{{A^2 }}{P} 〉 $$ whereN is the average number of cracks per unit volume, andA andP are the crack area and perimeter respectively. (For circular cracks of radiusa, ɛ=N〈a3〉.) Although a straightforward relationship does connect ɛ with the porosity, it may be more meaningful for laboratory experiments to concentrate upon measuring crack-induced variations as functions of crack density rather than of porosity. For saturated cracked rocks, the results of the calculations indicate that, in addition to ɛ, variations in conductivity depend also upon a saturation parameter Ω, which relates crack aspect ratio α to matrix and fluid conductivities σ and σF $$\Omega = \frac{{{\sigma \mathord{\left/ {\vphantom {\sigma {\sigma _F }}} \right. \kern-\nulldelimiterspace} {\sigma _F }}}}{\alpha }.$$
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    Pure and applied geophysics 117 (1978), S. 761-771 
    ISSN: 1420-9136
    Keywords: Gravity anomalies ; Magnetic anomalies ; Dikes ; Potential fields of ; Wavenumber domain
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    Notes: Abstract The interpretation of the gravity and magnetic fields from inclined dikes has been studied with artifical data contaminated by various noise components: base level, linear trend, and random noise. A Gaussian window was applied to the data prior to transformation to reduce the influence of noise as demonstrated by an analysis of the horizontal cylinder. The case of the dike is more complicated due to the fact that its spectrum has a number of zeroes at wavenumbers which are inversely related to the width of the dike. Around these wavenumbers, especially the random noise distorts the spectrum making interpretation ambiguous.
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    Pure and applied geophysics 117 (1978), S. 806-815 
    ISSN: 1420-9136
    Keywords: Antarctica ; Age of ; Surface wave disperison ; Precambrian shields
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    Topics: Geosciences , Physics
    Notes: Abstract Rayleigh wave dispersion measurements across East Antarctica give high phase velocities to periods as long as 75 sec. These are characteristic of the other Precambrian shields of the world.
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    Development genes and evolution 184 (1978), S. 155-170 
    ISSN: 1432-041X
    Keywords: Developmental restrictions ; Compound eye ; Pattern formation ; Genetic mosaics ; Drosophila
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    Topics: Biology
    Notes: Summary Five regions of the compound eye have been found to be preferential boundaries for clones of labelledMinute + cells, and to act restrictively on the growth of cell clones after a given developmental stage. One of these regions is topographically related to the line of pattern inversion existing at the level of the equator. The results of experiments showing independency of origin of restriction lines and line of pattern inversion are reported.
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    Development genes and evolution 184 (1978), S. 171-180 
    ISSN: 1432-041X
    Keywords: Xenopus ; Blastula ; Neurula ; Tail-bud stage ; Nuclear proteins ; Electrophoresis
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    Topics: Biology
    Notes: Summary The changes in saline-soluble, 0.35 M NaCl-soluble and the residual fraction of nuclear proteins during early development ofXenopus were studied by analytical electrophoresis on sodium dodecyl sulfate polyacrylamide gel. The fractions were obtained by consecutive extraction of nuclei from the blastula, neurula and tail-bud stage of development. No qualitative and only limited quantitative differences were found when the proteins of any of the three fractions isolated from the neurula stage were compared with the proteins of the corresponding fraction isolated from the tail-bud stage. But the electrophoretic pattern of each of the three fractions of the nuclear proteins from the blastula stage differs significantly from the electrophoretic pattern of the same fraction isolated from the neurula or tail-bud stage. Compared with the blastula stage, in the two later stages the relative amounts of chromosomal proteins with apparent molecular weights below 30,000 are decreased. Proteins which migrate in electrophoresis in the positions of the very lysine-rich histones and of the proteins of the nuclear ribonucleo-protein particles are indicated among the chromosomal proteins of the blastula stage, and are visible as strong bands in the electrophorogram of 0.35 M NaCl-soluble proteins extracted from neurula or tail-bud stage nuclei.
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  • 56
    ISSN: 1432-041X
    Keywords: Ultrastructure ; Scanning cytophotometry ; Chromatin ; Chondrocytes ; Regeneration
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    Topics: Biology
    Description / Table of Contents: Résumé Les cellules cartilagineuses des membres postérieurs deTriturus cristatus en régénération après amputation, ont été étudiées en microscopie électronique et par cytophotométrie à balayage. Nous nous sommes intéressés à la structure et à la distribution de la chromatine mais aussi à différents organites cytoplasmiques. Dans l'étude de cytophotométrie à balayage, la chromatine a été considérée à travers son constituant majeur, l'ADN, coloré par la réaction de Feulgen. Au cours de la régénération du membre, l'hétérochromatine initialement condensée, essentiellement accolée à la membrane nucléaire se décondense. Les vacuoles du cytoplasme, caractéristiques des animaux âgés par rapport aux animaux jeunes, disparaissent, les mitochondries et le reticulum endoplasmique rugueux deviennent plus abondants. Les caractéristiques nucléaires de l'activation cellulaire apparaissent précocement, précédent les modifications cytoplasmiques et conduisent à des cellules en tous points identiques aux cellules d'animaux jeunes en dehors de tout processus régénératif. Cette phase d'euchromatisation et de restructuration cytoplasmique est peut-être nécessaire à l'accroissement d'activité métabolique et à la division cellulaire qui suivent. Son déroulement peut expliquer tout au moins le ralentissement de la régénération observé chez les animaux âgés par rapport aux animaux jeunes.
    Notes: Summary Cartilaginous cells of aged newts (Triturus cristatus) were studied during hind limb regeneration. The electron microscope was used to study the structure and distribution of chromatin in the cell nuclei, while the DNA content of the chromatin was measured by means of a scanning cytophotometer. Changes in the ultrastructure of the cytoplasm during regeneration were also studied. It was observed that the structure and distribution of chromatin in the activated cell is greatly modified. In the non-activated cell of the aged newt, the chromatin is found highly condensed and distributed peripherally close to the nuclear membrane. In contrast, in the activated cells, the chromatin is much less condensed and is distributed throughout the nucleus. Moreover, cytoplasmic vacuoles, found only in the non-activated aged cells, disappear and an increase in the mitochondria and rough endoplasmic reticulum is also observed. Changes in the nuclear structure are observed prior to the cytoplasmic modifications. It is interesting to note that the process of activation induces structural changes in the aged cells which make these cells appear to be structurally identical to the young cells. This process of rejuvenation takes 3–5 days in the newt. We suggest that these structural changes of the chromatin and cytoplasm in the aged cells are necessary to increase the metabolic activity which precedes cell division. It may also explain why regeneration takes a longer time in the aged animals than in the young ones.
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    Development genes and evolution 184 (1978), S. 273-283 
    ISSN: 1432-041X
    Keywords: Nervous system ; Development ; Imaginal discs ; Drosophila
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    Topics: Biology
    Notes: Summary The pathway of adult sensory nerves has been analysed in three experimental situations: (i) in flies with grossly abnormal thoracic morphology resulting from X-irradiation early during development, (ii) in flies which had been subjected to surgical operations late in the larval period, (iii) in homoeotic mutants. The results provide experimental support for a simple mechanism in which developing adult axons join the nearest larval nerve and are guided by it up to the central nervous system. In particular, experimental interference with normal development can result in nerves from different segments, or from dorsal and ventral appendages, joining each other and entering the central nervous system together.
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    Development genes and evolution 184 (1978), S. 29-40 
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    Topics: Biology
    Notes: Summary Isolated cells from the siliceous spongeGeodia cydonium have been studied with respect to their partition behaviour in a two-phase aqueous polymer system. With this method it is possible to determine subtle changes in the cell surface charge. Addition of a homologous aggregation factor to the isolated cells lowers the partition rate, a finding which indicates that after binding of the aggregation factor to the cells their surface charge is reduced. The partition rate of the cells is strongly correlated with their content of membranebound sialic acid. Sixty-nine percent of the total, membrane-bound hexuronic acid is associated with the aggregation receptor; 1.8×107 aggregation receptor molecules are present on the surface of one cell which means that the average surface density amounts to 2.8×105 molecules per μm2. Removal of the aggregation receptor molecules from the cell surface results in a decrease of the partition rate in the two-phase system. After charging the receptor-depleted cells with soluble aggregation receptor, the partition behaviour of these cells can be reconstituted.
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    Development genes and evolution 184 (1978), S. 75-82 
    ISSN: 1432-041X
    Keywords: Egg shape ; Pole cell transplantation ; Sterility ; Drosophila
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    Topics: Biology
    Notes: Summary Females homozygous for a newly isolated mutation induced by ethyl methane sulphonate,fs(1)K10, lay abnormally shaped eggs in which the dorsal appendages of the chorion are enlarged and fused ventrally. The eggs are usually not fertilized and development is never normal beyond the blastoderm stage. The mutant was mapped to the tip of the X-chromosome with a meiotic position of 1–0.5 and a cytological location between 2B17 and 3A3. Using germ line mosaics constructed by transplantation of pole cells, it was shown that the abnormal morphology and the sterility are obtained only when the germ line is homozygous for the mutant.
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    Development genes and evolution 184 (1978), S. 109-113 
    ISSN: 1432-041X
    Keywords: Oocyte ; Germinal vesicle ; Cleavage ; Acipenser
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    Topics: Biology
    Notes: Summary Experiments with oocyte enucleation and transplantation of germinal vesicles show that already at the beginning of the period of rapid growth, the oocyte karyoplasm contains the substances necessary for the appearance in the cytoplasm of the ability to divide.
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    Development genes and evolution 184 (1978), S. 135-142 
    ISSN: 1432-041X
    Keywords: rDNA-Amplification ; Ovary ; Trophocytes ; Hybridization
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    Topics: Biology
    Notes: Summary In the meroistic insect ovary, the oocyte synthesizes little if any RNA. Most of the RNA which accumulates in the oocyte is synthesized by trophocytes. In the polytrophic meroistic ovary each oocyte is associated with a cyst containing 1,3,7 or 15 trophocytes. The trophocytes are derived from the same cell as the oocyte. The trophocyte cysts and the oocytes of the giant silkworm moth,Antheraea pernyi (Lepidoptera: Saturniidae), are large enough to enable their isolation by microdissection. The nucleus of each trophocyte is highly polyploid, containing hundreds of nucleoli. In order to determine whether DNA coding for rRNA (rDNA) is amplified in trophocytes ofA. pernyi, the percentage of the genome hybridizing with rRNA in somatic tissues was compared to that percentage in gametogenic tissues. RNA-DNA hybridization analysis indicates that approximately the same proportion (0.018%) of the DNA extracted from male and female gemetogenic tissues (testis, isolated trophocytes, and isolated oocytes) and somatic tissues (brain, Malpighian tubules) hybridizes with rRNA. The fact that DNA hybridizing with rRNA comprises the same proportion of the total DNA extracted from trophocytes, spermatogenic cells, and male and female somatic cells indicates that rDNA is not amplified in the trophocytes ofA. pernyi. In the polytrophic ovary, polyploidization of the entire trophocyte genome rather than amplification of a small part of it accounts for the increase of rDNA available for transcription.
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    Development genes and evolution 184 (1978), S. 181-193 
    ISSN: 1432-041X
    Keywords: Xenopus laevis ; Early embryo ; Lectin binding ; Cell surface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The composition of the surface coat in embryonic cells ofXenopus laevis was examined by agglutination and fluorescent staining with lectins. Cells of early and mid gastrula stages were agglutinated by lectins specific for D-mannose, D-galactose, L-fucose, N-acetyl-D-glucosamine and N-acetyl-D-galactosamine. No differences in agglutinability among ectoderm, mesoderm and endoderm cells were observed with lectins specific for D-mannose, D-galactose and N-acetyl-D-galactosamine, though agglutination of gastrula cells with fluorescent lectins revealed considerable differences in the intensity of lectin binding among cells within an aggregate. These differences in amount of lectin bound were not related to cell size or morphology. Patches of fluorescent material formed on the cells, suggesting that lectin receptors are mobile in the plane of the plasma membrane. In the early cleavage stages intensive lectin binding occurs only at the boundary between preexisting and nascent plasma membranes. The external surface of the embryo has few lectin receptors up to the late gastrula stage. The unpigmented nascent plasma membranes, when exposed to fluorescent lectins, do not assume any fluorescence distinguishable from the background autofluorescence of yolk, in stages up to the mid-blastula. From this stage onwards lectin binding was observed on the membranes of the reverse side of surface layer cells and on the membranes of deep layer cells. During gastrulation there is an accumulation of lectin-binding material on surfaces involved in intercellular contacts. The significance of lectin binding material for morphogenesis is discussed.
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  • 63
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    Development genes and evolution 184 (1978), S. 233-249 
    ISSN: 1432-041X
    Keywords: Tissue culture ; Muscles ; Metamorphosis ; Ecdysone ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The differentiation of muscles in primary cultures of cells fromDrosophila melanogaster embryos was investigated. In early cultures, and in the absence of exogenous ecdysone, two main classes of muscle were found. Comparison, by light and electron microscopy, of one of these classes (the “myotube” class) with muscles from third instar larvae shows that this class corresponds to the muscles of the body wall of the larva. When α- or β-ecdysone is added to the cultures, these undergo a number of metamorphic changes. Most of the larval muscles disappear, and two new types of muscle form. Ultrastructural and light microscopic examination of these two types indicates that they correspond to the two classes of skeletal muscle (fibrillar and tubular) found in adult flies.
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  • 64
    ISSN: 1432-041X
    Keywords: Ganglion of Remak ; Neural crest ; Cell migration ; Catecholamines
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    Topics: Biology
    Notes: Summary Isotopic and isochronic transplantation of fragments of quail neural tube into chick demonstrates that neural and glial cells of the entire ganglion of Remak (RG) arise from the lumbo-sacral level of the neural crest. The ganglioblasts first accumulate in the mesorectum (stage 24 of Hamburger and Hamilton, in the chick and I8 of Zacchei in the quail) and subsequently migrate cranially. Histochemical studies have been carried out on the rectal and cloacal parts of the quail RG at various stages of development. Cholinesterase activity can be detected as soon as the primordium is in place and the intensity of the reaction increases rapidly. During morphogenesis of the cloacal region the RG and the pelvic plexus become intimately associated. Catecholamine-containing cells are found first in the pelvic plexus, then in the cloacal part of the RG. Fluorescent cells are often grouped close to blood vessels and associated with non-fluorescent ganglia. Cranial to the level of the bursa of Fabricius, the RG is composed only of non-fluorescent neurons whatever the developmental stage considered (up to 1 day after hatching). The developmental capabilities of the RG of the 5-day quail have been tested by transplanting various parts of the hind-gut with the dorsal mesentery onto the chorio-allantoic membrane. Catecholamine-containing cells develop only in grafts including the cloacal region. By using quail-chick chimaerae in which the RG belongs to the quail while mesentery and gut are of chick origin, it was possible to show that neurons which develop in the graft (i.e. in the absence of preganglionic innervation), send nerve fibres into the gut wall. Moreover some neuroblasts located in the primordium of the RG migrate into the gut wall and give rise to some enteric ganglion cells. The contribution of the lumbo-sacral neural crest to the enteric ganglia, by this route, is discussed.
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  • 65
    ISSN: 1432-041X
    Keywords: Grasshopper ; Juvenile hormone-carrier ; Sexual behaviour ; Ovaries ; Spermatheca
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    Topics: Biology
    Notes: Summary Egg-production, spermathecal enzyme activity and sexual behaviour inGomphocerus rufus females are shown to be controlled by the corpora allata, i.e. the juvenile hormone (JH). The haemolymph of this insect contains a high molecular weight glyco-lipo-protein (220,000; IEP 6.8) which has a high affinity for JH (Kd=5×10−8M). This protein binds JH selectively, even in competition with other haemolymph lipoproteins. Purification of the JH-binding protein and subsequent immunisation of rabbits yielded a homogenous antibody solution (Anti-JCv) which eliminated the JH-transport in the haemolymph if it was injected into adult males or females for several days after ecdysis. After this treatment the females did not produce eggs, and spermatophore-formation occurred only partially in the males, this indicating that the Anti-JCv-injections had exactly the same effect as bilateral allatectomy. The haemolymph of related grasshoppers was shown to contain a protein which is immunologically identical to the JH-carrier from theG. rufus haemolymph. It is suggested that the JH produced by the c. allata needs a protein carrier in order to exert its control on the functioning of the reproductive system. The synthesis of the JH-carrier is not dependent upon the presence of JH, i.e. the c. allata, since it is also produced by bilaterally allatectomized males and females throughout their whole life.
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  • 66
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    Development genes and evolution 185 (1978), S. 19-36 
    ISSN: 1432-041X
    Keywords: Salamandridae ; Palate ; Dental lamina ; Vomerine bar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Im Bereich des Vomer und der sich während der Metamorphose bildenden Vomerspange wurden bei verschieden alten Larven vonSalamandra salamandra Defektsetzungen, Exstirpations- und Verlagerungsexperimente durchgeführt. Ein im Spangenbildungsbereich gesetzter Defekt beeinträchtigt das spätere Auswachsen der Vomerspange nicht. In Gewebsfragmenten, die aus der Spangenbildungszone entnommen und in eine andere Körperregion verpflanzt wurden, bilden sich keine Spangenstrukturen. Nach Entfernung des Vomer mit anhängendem Bindegewebe entwickelt sich keine Spange. Die Ausschaltung des palatinalen Anteils vom Pterygopalatinum hat keinen Einfluß auf die Spangenbildung; die Spange ist also keine “Vomeropalatinalspange”. Die Vomerspange bildet sich auch dann, wenn vor Beginn der Spangenbildung die dem Vomer zugeordnete Zahnleiste entfernt wurde. Somit steht fest, daß die Vomerspange keine “Zahnknochen”-Bildung im Sinne von Wintrebert (1922a-c) darstellt. Die caudale Verlängerung der Vomerzahnleiste ist an das Auswachsen der Vomerspange gebunden.
    Notes: Summary The relations between the osseous palate and its dental laminae in larvalSalamandra salamandra (L.) during metamorphosis were examined by various amputation procedures. Removal of the mucosa and the subepithelial tissue in the region where the differentiation of the osseous bar of the vomer (“Vomerspange”) takes place, does not prevent outgrowth of the bar. When this tissue material is transplanted into the subepithelial connective tissue of the body, structures similar to the bar are not formed. Amputation of the vomer and adhering connective tissue prevents the development of the bar, whereas removal of the palatinal part of the pterygopalatinum has no influence on its development. The vomerine bar does not therefore represent a “Vomeropalatinalspange” in the sense of Wintrebert. The caudal elongation of the dental lamina of the vomer is correlated with the outgrowth of the vomerine bar.
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  • 67
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    Development genes and evolution 185 (1978), S. 59-77 
    ISSN: 1432-041X
    Keywords: Nerve differentiation ; Pioneer fibres ; Imaginal discs ; β-ecdysone-Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An ultrastructural analysis is presented of the cuticular and neural structures formed by the prothoracic leg and wing imaginal discs of maleDrosophila melanogaster larvae during culture in vitro with 0.2 μg/ml of β-ecdysone. A pupal cuticle, and subsequently an imaginal cuticle with a well-defined epicuticle and a laminated endocuticle is formed. The ultrastructure of the epidermis and of cuticular structures such as bristles, trichomes, apodemes, and tracheoles is very similar to that found in situ. Dendrites and nerve cell bodies are formed in vitro, and sensory axons form nerve bundles similar to those of normal appendages in situ, despite their isolation from the central nervous system. It is concluded that at the ultrastructural level, differentiation in vitro closely parallels the normal course of development.
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  • 68
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    Development genes and evolution 192 (1983), S. 1-7 
    ISSN: 1432-041X
    Keywords: Fat body ; Basement membrane ; Ageing ; Transplantation ; Monoclonal antibody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The hemocytes oftu-Sz ts melanotic tumor larvae ofDrosophila melanogaster encapsulate heterospecific and surface-modified homospecific tissue implants, but do not encapsulate unmodified homospecific implants (R. Rizki and Rizki 1980). In the present study we usedtu-Sz ts hosts to assay changes in larval fat body surfaces during development. Donor fat bodies from various ages of larvae were accepted (remained unencapsulated) intu-Sz ts hosts whereas fat bodies from donors with everted spiracles and all subsequent stages of development that were tested were rejected (encapsulated). Since the demarcation between acceptance and rejection by thetu-Sz ts blood cells did not coincide with the gross morphological changes that appear in the fat body during metamorphosis (dissolution of the basement membrane and dispersal of the freed fat body cells at pupation), we compared acceptable and nonacceptable fat body surfaces by three other methods. Fat body surface ultrastructure was examined, fat bodies were treated with fluorescein isothiocyanate-conjugated lectins, and fat body surfaces were reacted with a monoclonal antibody specific for basement membrane. These approaches did not uncover fat body surface changes associated with eversion of the anterior spiracles, suggesting that recognition of tissue surface heterogeneities by the insect hemocytes exceeds the resolving power of the other three methods. However, the monoclonal antibody fails to bind to the basement membrane ofD. virilis larvae, whose fat body is always rejected intu-Sz ts hosts. This supports our suggestion that the molecular architecture of the basement membrane may be important in eliciting the encapsulation response.
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  • 69
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    Development genes and evolution 192 (1983), S. 13-20 
    ISSN: 1432-041X
    Keywords: Hydra carnea ; Fertilization ; Sperm-egg interactions ; Site-specificity
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    Topics: Biology
    Notes: Summary Fertilization in the freshwater hydrozoanHydra carnea has been examined by light, scanning and transmission electron microscopy. Sperm penetrate the jelly coat which covers the entire egg surface only at the site of the emission of the polar bodies. The egg surface exhibits a small depression, the so called fertilization pit at this site. Sperm-egg fusion takes place only at the bottom of the fertilization pit.Hydra sperm lack a structurally distinct acrosome and in most of the observed cases, fusion was initiated by contact between the membrane of the lateral part of the sperm head and the egg surfacce. Neither microvilli nor a fertilization cone are formed at the site of gamete fusion. The process of membrane fusion takes only a few seconds and within 1 to 2 min sperm head and midpiece are incorporated in the egg. Electron dense material is released by the egg upon insemination but cortical granule exocytosis does not occur and a fertilization envelope is not formed. The possible polyspermy-preventing mechanisms in hydrozoans are discussed. Hydra eggs can be cut into halves whereupon the egg membranes reseal at the cut edges and the fragments assume a spherical shape. Fragments containing the female pronucleus can be inseminated and exhibit normal cleavage and development. The observation that in such isolated parts the jelly coat will not fuse along the cut edges was used to determine its role in site-specific gamete fusion. These experiments indicate that site-specificity of gamete fusion can be attributed to special membrane properties at the fertilization pit.
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  • 70
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    Development genes and evolution 192 (1983), S. 28-36 
    ISSN: 1432-041X
    Keywords: Budding ; Polarity ; Positional information ; Ascidian
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    Topics: Biology
    Notes: Summary In the polysteelid ascidian,Polyandrocarpa misakiensis, buds can arise at any antero-posterior positional level around the basal margin of a functional zooid. In this study, each bud was cut into anterior and posterior halves along its proximo-distal axis. When an anterior half was combined with a posterior half from a higher (more posterior) level, the future zooid developed the same anteroposterior polarity as a normal bud. When the same operation was performed with a posterior half from a lower (more anterior) level, the antero-posterior polarity was inverted, resulting in a reversed body asymmetry (situs inversus viscerum). Bud polarity depended not on the size or the growth stage of the fragmented buds, but on the difference in parental positional levels from which respective buds to be fused had originated. Surgically constructed doublehalf buds developed a single polarity instead of a pattern reduplication. Insertion experiments with bud pieces showed that the gap between the positional levels was recognized at the proximal region of operated buds. The results of this study are inconsistent with the predictions of the polar coordinate model for pattern formation. It is concluded that a parent zooid possesses antero-posterior position-specific potential for determining bud polarity.
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  • 71
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    Development genes and evolution 192 (1983), S. 37-41 
    ISSN: 1432-041X
    Keywords: Tunicamycin ; Exogastrulation ; Neural induction ; Cell permeability
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    Topics: Biology
    Notes: Summary Bufo arenarum eggs at late blastula and gastrula were treated with tunicamycin, an inhibitor of glycoprotein glycosylation, to investigate its effects on morphogenesis and neural induction. Because of the low permeability of the amphibian egg to a number of drugs, the blastocoel was opened surgically prior to treatment. Almost all of the eggs treated with the antimetabolite, at a concentration of 10 μg/ml, from late blastula stage for 24h exhibited exogastrulation. The effect is dose- and stage-dependent as shown by the lower proportion of exogastrulae obtained when eggs are treated at a lower concentration (5 μg/ml) or after the onset of gastrulation. Treatment with the antimetabolite did not interfere with neural induction, as partial exogastrulae developed a small neural tube. The most striking biochemical effect was an enhanced uptake of glucose, mannose and leucine. The incorporation of mannose into acid-insoluble material was severely inhibited by tunicamycin, with a concomitant decrease of leucine incorporation into the acid-soluble pool.
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  • 72
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    Development genes and evolution 184 (1978), S. 143-153 
    ISSN: 1432-041X
    Keywords: Insect embryogenesis ; 3H-uridine precursor conversion ; Polyadenylated RNA ; Maternal RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung In der Oogenese und frühen Embryogenese markierte Nukleinsäuren wurden aus Eiern der ZikadeEuscelis plebejus isoliert. Poly(A)-haltige RNS wird in frühen Oogenesestadien in die Oocyte eingebaut. Im frisch abgelegten Ei beträgt ihr Anteil am RNS-Gehalt etwa 2,7%. Im Molekulargewicht ist diese Fraktion (15–32 S) deutlich verschieden von poly(A)-haltiger RNS aus dem embryonalen Markierungszeitraum zwischen früher Furchung und Vorkeimanlagenstadium (4–20 S). Am vorderen Eiende injiziertes3H-Uridin war innerhalb von 3 h gleichmäßig über den Eiraum verteilt. Als3H-Uridin im frühen Furchungsstadium injizierte Markierung fand sich in späteren Stadien (nach 10–10 h) in hohem Umfang in DNS eingebaut (25–35%); markierte RNS konnte erst im zellulären Blastodermstadium nachgewiesen werden. Bei getrennter Aufarbeitung von Dotter-Endoplasma und Blastodermzellen war nur in den letzteren eine embryonale RNS-Synthese erkennbar. Von der im Embryo markierten RNS lagen im frühen Blastodermstadium etwa 10% als poly(A)-haltige RNS vor, im frühen Keimanlagenstadium nur etwa 3%. Anteriore und posteriore Eihälften im frühen Keimanlagenstadium zeigten keine Unterschiede der Molekulargewichte ihrer poly(A)-haltigen RNS.
    Notes: Summary RNA labelled during oogenesis or early embryogenesis was isolated from eggs of the leaf hopperEuscelis plebejus. The polyadenylated RNA fraction deposited during early oogenesis accounted for approximately 2.7% of the total RNA content of the newly laid egg. This fraction differed significantly in molecular weight (15–32 S) from poly(A)-containing RNA synthesised between early cleavage and early germ anlage stages (4–20S). Locally injected3H-uridine spread through the egg within approximately 3 h. A considerable fraction (25–35%) of label injected as3H-uridine during early cleavage was recovered in DNA at subsequent stages (10–20 h later); labelled RNA was not found prior to the cellular blastoderm stage. When the yolk-endoplasm was separated from the blastoderm cells, only the latter contained demonstrable amounts of RNA synthesised by the embryo. Of the precursor incorporated into embryonic RNA, approximately 10% was found in the polyadenylated fraction at the early blastoderm stage, but only 3% at the early germ anlage stage. No differences in size distribution of polyadenylated RNA were evident between anterior and posterior halves of the early germ anlage stage.
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    Development genes and evolution 192 (1983), S. 51-51 
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  • 74
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    Development genes and evolution 192 (1983), S. 48-50 
    ISSN: 1432-041X
    Keywords: Drosophila ; Hybrid lethality ; Imaginal discs ; Interspecific transplantation
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    Topics: Biology
    Notes: Summary Females ofDrosophila melanogaster, crossed with males ofDrosophila mauritiana, produce only female offspring. The male hybrid larvae grow very slowly, fail to pupate and die after prolonged larval life. Imaginal discs from these male hybrids transplanted into Drosophila melanogaster larvae can give rise to adult structures with normal patterns. Differentiation of hybrid imaginal disc tissue is improved by short term culture in non-hybrid larvae prior to metamorphosis, suggesting that the hybrid larval haemolymph is inadequate to sustain normal imaginal disc growth. This may represent the physiological basis of the reproductive isolating mechanism separating the twoDrosophila species
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  • 75
    ISSN: 1432-041X
    Keywords: Immunofluorescence ; Telotrophic Meroistic Ovary ; Postribosomal Particles ; Insect Oogenesis ; Early Insect Development
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    Topics: Biology
    Notes: Summary During previtellogenesis, the oocytes of the telotrophic meroistic ovary ofDysdercus are provided with ribosomes and ribonucleoprotein (RNP) particles by the nurse cells. At the end of vitellogenesis, the oocyte itself becomes active as shown by autoradiography. The proteins synthesized by the oocyte are stored in cytoplasmic postribosomal particles which are preformed by the tropharium. The proteins of these particles were separated by SDS polyacrylamide gels and their endogenous oocyte proteins revealed by fluorography. The synthesis, transport, and storage of the postribosomal particles are demonstrated by indirect immunofluorescence. The young oocytes of previtellogenic follicles show a diffuse distribution of these particles. In late vitellogenesis, fluorescence becomes more and more concentrated in spots throughout a distinct region in the middle part of the oocyte. Thus, in freshly laid eggs, the periplasm is free of fluorescence. During migration of the cleavage nuclei the postribosomal particles were shifted into the cortex. Fluorescence is then most intense in the periplasmic region. During blastoderm formation, however, fluorescence decreases.
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  • 76
    ISSN: 1432-041X
    Keywords: Early neurogenesis ; Neurogenic mutants ; Drosophila
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    Notes: Summary The central nervous system (CNS) ofDrosophila develops from precursor cells called neuroblasts. Neuroblasts segregate in early embryogenesis from an apparantly undifferentiated ectoderm and move into the embryo, whereas most of the remaining ectodermal cells continue development as epidermal cell precursors. Segregation of neuroblasts occurs within a region called the neurogenic field. We are interested in understanding how the genome ofDrosophila controls the parcelling of the ectoderm into epidermal and neural territories. We describe here mutations belonging to seven complementation groups which effect an abnormal neurogenesis. The phenotypes produced by these mutations are similar. Essential features of these phenotypes are a conspicuous hypertrophy of the CNS accompanied by epidermal defects; the remaining organs and tissues of the mutants are apparently unaffected. The study of mutant phenotype development strongly suggests this phenotype to be due to misrouting into the neural pathway of development of ectodermal cells which in the wildtype would have given rise to epidermal cells, i.e. to an initial enlargement of the neurogenic region at the expense of the epidermogenic region. These observations indicate that the seven genetic loci revealed by the mutations described in this study contribute to control the neurogenic field. The present results suggest that in wildtype development neurogenic genes are supressed within all derivatives of the mesoderm and endoderm and some derivatives of the ectoderm, and conditionally expressed in the remaining ectoderm. The organisation of the neurogenic field in the wildtype is discussed.
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  • 77
    ISSN: 1432-041X
    Keywords: Gastropoda ; Mesoderm induction ; Dorsoventral polarity ; Epigenetics ; Mosaic/regulative development
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    Topics: Biology
    Notes: Summary In equally cleaving gastropods, the interactions between micromeres and macromeres involved in the determination of the mesentoblast mother cell (3D) were studied by changing the spatial arrangement of the micromeres by deleting one first quartet micromere or its progeny. A fixed relation was found between the deletion site and the place of origin of 3D; therefore, a fixed relation also exists in the configuration of the three remaining first quartet micromeres and the 3D. These results argue against the possibility that the animal-vegetal interactions do not choose between macromeres, but only permit the expression of a choice already made in another way and at another moment. The results are consistent with a stochastic model in which accidental differences between the macromeres in the number or extent of contacts with first quartet micromeres play a discriminating role during micromere — macromere interactions, that lead to 3D determination. Embryos which lack a given first quartet micromere show a total absence of regulation in the larval head pattern; only the cephalic plates show regulative abilities while forming the adult head structures. Therefore, in later stages new activating and restraining factors seem to play a part in the head development.
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    Development genes and evolution 192 (1983), S. 86-94 
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    Keywords: Dictyostelium discoideum ; Pattern formation ; Differentiation markers
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    Topics: Biology
    Notes: Summary The appearance and spatial distrubution of ultrastructural markers ofDictyostelium discoideum differentiation were quantitatively analysed. Our results combined with data from the literature on the functions of cells at various stages of development lead to the following conclusions. When food is no longer available all amoebae initially develop an autophagic apparatus in order to sustain metabolism. After slugs have been formed, autophagy is suppressed in the prespore cells. During aggregation a number of cells gradually form prespore characteristics. These cells arise at random but later they become located in the basal part of the tip-forming aggregate. From the early slug stage onwards, cells of the posterior two third region gradually enter into the prespore pathway. During prolonged slug migration the optimal acquirement of prespore characteristics is blocked. Cells of the anterior region show no active differentiation but they maintain the morphology and most of the functions of aggregating cells. At the rear-guard of the slug and later on in the basal region of the maturing fruiting body, a second anteriorlike region appears. Actual stalk cell differentiation takes place only at the apex and at the base of the developing fruiting body.
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    Development genes and evolution 192 (1983), S. 95-102 
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    Keywords: Polychaeta ; Typosyllis ; Reproduction ; Endocrine control
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    Topics: Biology
    Notes: Summary When exposed to a “winter” light-temperature cycle, reproduction in the polychaeteTyposyllis prolifera is inhibited by a hormone from the proventriculus. When exposed to a “summer” cycle, worms show periodic reproduction following an endogenous lunar rhythmictiy. The endocrine system mediating the stimulation of reproduction by summer conditions, was studied by extirpation and transplantation of prostomium and/or proventriculus. A previously unknown prostomial hormone was found to play a major role in this process. Summer conditions induce a temporary endocrine activity in the prostomium. This homone probably does not act directly on peripheral targets, but stimulates reproduction by inactivating the proventricular endocrine system. The experimental evidence of a hierarchic neuroendocrine system governing reproductive activity in syllid polychaetes is discussed.
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    Development genes and evolution 192 (1983), S. 108-112 
    ISSN: 1432-041X
    Keywords: Gangliosides ; Fetal human brain ; Acetylcholinesterase
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    Topics: Biology
    Notes: Summary Correlative histological, histochemical and biochemical investigations on laminar compartments from four different areas of fetal human neopallium at 28 weeks of gestation revealed discrete distribution of gangliosides in the cerebral wall. Highest level of total ganglioside concentration was found in the layers of cortical anlage (cortical plate and “subplate layer”) which are concomittantly characterized by highest activity of acetylcholinesterase (AChE) and which are known to be involved in intensive synaptogenesis at this stage of cortical development. In three of four areas the proportion of GD1a — ganglioside from total ganglioside amount tended to increase and that of GT1b to decrease from inside (ventricle) to outside (cortical anlage) throughout the cerebral wall.
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    Development genes and evolution 185 (1978), S. 167-183 
    ISSN: 1432-041X
    Keywords: Endoderm ; Chordo-mesoderm ; Rana ; Differentiation ; Morphogenetic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Du cordo-mésoderme dorsal greffé sur la région ventrale d'un massif endodermique de même âge provoque sa différenciation locale (st. 17/neurula). Des néo-formations nombreuses et variées sont obtenues en faisant varier les caractéristiques du greffon (cordo-mésoderme) et du porte-greffe (endoderme). L'existence, la nature et le volume de ces néo-formations dépendent: de l'étroitesse et de la durée du contact greffon/porte-greffe, de l'âge du cordo-mésoderme et de l'âge de l'endoderme, des niveaux de contact, plus ou moins antérieurs, du greffon et du porte-greffe. Les résultats des greffes (st. 17) sont interprétés grâce à la construction de modèles théoriques. Ces modèles sont bâtis sur les quatre paramètres suivants: 1) l'existence de 2 facteurs morphogénétiques, l'un de nature endodermique et l'autre de nature cordo-mésodermique. Ces 2 facteurs sont responsables de l'apparition de néo-formations; 2) la localisation de ces 2 facteurs actifs dans les deux tiers (antérieur et moyen) de l'endoderme et du cordo-mésoderme; 3) la décroissance de l'activité des 2 facteurs selon l'axe antéro-postérieur de l'embryon; 4) le rôle différent de chacun de ces 2 facteurs. Le facteur endodermique déterminerait la nature et la taille des néo-formations; le facteur cordo-mésodermique jouerait un rôle stimulant. Une discussion est engagée sur la méthode, la démarche et l'intérêt de ce type d'interprétation des résultats.
    Notes: Summary Chordo-mesoderm grafted onto the ventral area of yolk endoderm of the same age causes its local differentiation (Rana dalmatina: st. 17/neurula). Numerous and various neo-formations are achieved by variation of the grafted tissue (chordo-mesoderm) and host (endoderm) characteristics. The existence, the constitution and the volume of the neo-formations are dependant on: the tightness and the duration of the graft/host contact, the age of the chordo-mesoderm and the age of the endoderm, and the antero-posterior level of contact with grafted tissue and host. The results of the grafts (st. 17) are explained by the elaboration of a theoretical model. These models are elaborated according to four parameters: (1) the existence of two morphogenetic factors, one endodermal and the other mesodermal. These two factors are responsible for the constitution of “neo-formations”; (2) the localization of these two factors, active in the anterior and median thirds of the endoderm and the chorda-mesoderm; (3) decreasing activity of these two factors along to the antero-posterior axis of the embryo; (4) the different notes of each of these two factors. The endodermal factor might determine the constitution and the size of the neo-formations; the chordo-mesodermal factor might play a stimulatory role. The method, the procedure and the interpretation of this kind of results are discussed.
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    Development genes and evolution 192 (1983), S. 120-129 
    ISSN: 1432-041X
    Keywords: Intracellular inhibition ; Polar lobe-Polychaeta ; Embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The embryo ofSabellaria cementarium (Polychaeta) forms a polar lobe at each of the first two cleavage divisions which becomes absorbed into one of the blastomeres at the end of the division. Lobe removal experiments show that the polar lobe preceding first cleavage is necessary for the development of the apical tuft and the posttrochal region of the trochophore larva. The polar lobe preceding second cleavage is smaller than the first polar lobe and is necessary only for post-trochal region development. In blastomere isolation experiments, isolates containing the C but not the D blastomere form apical tufts. Isolates containing the D but not the C blastomere do not form apical tufts. When the polar lobe preceding second cleavage is removed and the C and D blastomeres are separated and raised in isolation, each can form an apical tuft. When the second cleavage is equalized with sodium dodecyl sulfate (SDS) such that both the C and the D blastomeres receive second polar lobe material, no apical tuft is formed. These results suggest that apical tuft determinants are distributed to both the C and D blastomeres at second cleavage but that the second polar lobe contains an inhibitor for apical tuft formation which is shunted to the D blastomere after the completion of second cleavage.
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  • 83
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    Development genes and evolution 192 (1983), S. 130-137 
    ISSN: 1432-041X
    Keywords: Vegetalizing factor ; Inducer concentration ; Incubation time with inducer ; Pattern formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Early amphibian gastrula ectoderm (Xenopus laevis) has been treated with vegetalizing factor using the sandwich technique, varying the period of incubation and the inducer concentration. The pattern of induced tissues depends on three factors: the inducer concentration, the size of inducer pellet and the time of exposure of ectodermal target cells to inducer. Short treatment with inducer will result in the formation of blood cells and heart structures. An increase in incubation time or inducer concentration, or both, will cause the formation of increasing amounts of such dorsal mesodermal structures as pronephros, somites and notochord. Neural structures can only be observed in explants with considerable amounts of somites and notochord. Ectoderm treated with high concentrations of vegetalizing factor for the whole period of competence will differentiate into endoderm. Furthermore, the results show thatX. laevis ectoderm does not show any autoneuralizing tendency under our experimental conditions. It therefore seems to be a suitable tool for the study of primary embryonic induction.
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  • 84
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    Keywords: Mouse embryogenesis ; Cytochalasin B ; Polyploid ; Chromosome replication ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cleavage of fertilized mouse eggs was prevented during cytochalasin B incubation and consequently these eggs became tetraploid the following day during in vitro culture. When the eggs were cultured further in normal medium, they cleaved and gave rise to tetraploid blastocysts. Protein synthesis was analysed in these embryos at different developmental stages using two-dimensional polyacrylamide gel electrophoresis. The protein synthesis pattern of one-cell tetraploid eggs was intermediate between those of normal one- and two-cell embryos. Tetraploid two-cell embryos expressed protein sets equivalent to those of untreated four-cell embryos, and tetraploid four-cell embryos synthesized proteins similar to those of four- to eight-cell controls. At subsequent pre-implantation stages the asynchrony was no longer detectable. When fertilized eggs were cultured continuously in the presence of cytochalasin B, they became tetraploid, octoploid and more and more polyploid without cleavage occurring. The protein synthesis patterns expressed by these one-cell polyploid eggs did not resemble that of normal fertilized eggs, but were similar to those of cleaving control embryos and blastocysts of equivalent age and nuclear division. These results strongly suggest that in early mouse embryos stage-specific translation is temporally correlated with chromosome replication (karyokinesis) and independent of cell division (cytokinesis) or cell interaction.
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    Development genes and evolution 192 (1983), S. 152-158 
    ISSN: 1432-041X
    Keywords: Calliphora ; Fat body ; RNA polymerase ; Ecdysteroids
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    Topics: Biology
    Notes: Summary In vivo labelling of RNA polymerases I and II with S35-methionine shows that ecdysterone causes a de novo synthesis of both enzymes in nuclei of fat body cells inCalliphora 3rd instar larvae. Binding experiments with H3-α-amanitin demonstrate that the concentration of RNA polymerase II molecules increases two- to threefold within 3 h after ecdysterone treatment. The enhanced polymerase concentration coincides with an enhanced enzymatic activity and an increase in RNA synthesis in response to ecdysteroids.
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  • 86
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    Keywords: Embryonic induction ; Epithelial cell differentiation ; Organ culture ; Immunoperoxidase
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    Notes: Summary Undifferentiated metanephric mesenchymes, when grown in transfilter contact with an inductor tissue, differentiate into epithelial kidney tubules. The segregation of these tubules into the different segments of the nephron was studied. In explants grown in continuous transfilter contact with the inductor, immunohistological and histochemical markers specific for the glomerular epithelial, proximal tubule, and distal tubule cells appeared by 4 1/2 to 5 days, 4 days, and 5 days of culture, respectively. Electron microscopy confirmed segmentation of the tubules: Avascular glomeruli with glomerular basement membrane material, proximal tubules with brush border formation, and distal tubules were revealed in the explants after 5 days of culture. A short (18 h) transfilter induction pulse, followed by a prolonged subculture in the absence of the inductor, resulted sulted in the formation of only a small number of tubules in about half of the explants while the rest remained undifferentiated. These scarce tubules showed the markers specific for the proximal tubules only. The segregation of all three aspects of the nephron seems to be programmed during the transfilter culture, but apparently the time needed for the induction of the different segments varies.
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    Development genes and evolution 192 (1983), S. 159-163 
    ISSN: 1432-041X
    Keywords: RNA synthesis ; Early insect embryogenesis ; Nucleotide pools
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    Topics: Biology
    Notes: Summary The total amount of ATP and UTP was measured in embryos ofDrosophila melanogaster andBruchidius obtectus at different development stages. The pool-sizes were measured by their ability to enhance poly(AU) synthesis in an in vitro test, using RNA polymerase ofE. coli, poly-d(AT), ATP, and3H-UTP. In embryos ofD. melanogaster, the amount of UTP decreased from 4.5 pmoles/ embryo during cleavage and early blastoderm to 2 pmoles at later stages. The ATP pool decreased from 14 pmoles/ embryo to 6 pmoles at the same developmental stages. In embryos ofB. obtectus, the UTP pool expanded from about 1 pmole/embryo during cleavage and early blastoderm to about 3 pmoles during gastrulation and organogenesis. Much more ATP was found inB. obtectus embryos: during fertilization 23 pmoles/embryo were found. At late syncytial blastoderm stages the amount of ATP rose to about 50 pmoles/embryo. At cellular blastoderm stages and during gastrulation only 26 pmoles/embryo of ATP were found. During organogenesis the ATP pool decreased to about 14 pmoles/embryo.
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    Development genes and evolution 192 (1983), S. 179-188 
    ISSN: 1432-041X
    Keywords: Pattern formation ; Molecular asymmetries ; Mirror-image doublets ; Cortical pattern ; Ciliate
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    Topics: Biology
    Notes: Summary Mirror-image doublets of the hypotrich ciliateParaurostyla weissei were induced by modifying culture conditions. Successive steps of doublet formation involve inhibiting the separation of daughter cells during cell division and the shifting of these to attain a parallel configuration. The posterior part of the adoral band of membranelles in the right component then turns to the left and fuses with the distal terminal of the membranellar band in the left component. In effect, part of the adoral band and some of the paroral membranelles become apposed upside down, and the paroral membranelles of the right component are located on the left side of the adoral membranelles. A new site of oral primordium formation is initiated at the junction of the two oral apparatuses, the ciliature of which is arranged in a mirror-image pattern. During further cortical reorganization, the whole body ciliature of the right component becomes organized as a mirror-image of the normal left component. Both components of the doublet show the same ultrastructure of body ciliature and lack the right marginal cirri; the symmetry-reversal half, however, possesses multiple rows of left marginal cirri. The individual adoral membranelles and paroral membranelles in the symmetry-reversal component are rotated anteroposteriorly. Some aspects of the patterning of cortical structures are discussed.
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    Development genes and evolution 192 (1983), S. 222-227 
    ISSN: 1432-041X
    Keywords: Silkmoth chorion ; Transcription ; Northern analysis
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    Topics: Biology
    Notes: Summary cDNA clones for two distinct families ofBombyx mori chorion protiens, Class A (m2774) and Class Hc (m5000), were used to study the developmental regulation of specific chorion mRNAs. Individual follicles from maturing ovarioles were assayed by Northern blotting techniques and amino acid pulse-labeling to determine concomitant RNA accumulation and protein synthesis patterns with a temporal resolution of 2.2–2.6 h of developmental age. RNAs hybridizing to the two cloned chorion sequences at high criterion showed distinctive, non-overlapping patterns of accumulation during the middle-late and very late stages of choriogenesis. Moreover, the periods of expression of these RNAs coincided exactly with the synthetic periods of two distinct subsets of chorion proteins, one containing Class A and B components, and the other containing Class Hc components alone. These results suggest that chorion gene transcription and translation are tightly coupled.
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  • 90
    ISSN: 1432-041X
    Keywords: Amphibia ; Cleavage cycle ; Gastrulation ; Asymmetry ; Time-lapse cinematography
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    Topics: Biology
    Notes: Summary The animal and the vegetative side of 15 embryos ofXenopus laevis were studied from the 5th cleavage to gastrulation by means of time-lapse cinematography. The duration of cleavage cycles, defined for the embryo as a whole as the period between the earliest blastomere divisions of one cycle to those of the next, varies quite a lot between individual embryos, both with respect to synchronous and lengthened cycles. Cycle lengthening may start at either cycle 10, 11 or 12. Cycle 13 deviates from the individual rhythm, and moreover its duration is inversely correlated with the period elapsing from the beginning of this cycle to the onset of gastrulation which occurs in cycles 14 or 15. In each cleavage cycle, the regional sequence of first blastomere divisions is visible on films as a “cleavage wave” runming over the animal cap. The direction of the waves varies in different embryos during the synchronous period but begins to change from cycle 10 onwards, resulting in a similar direction in most embryos prior to gastrulation: from the ventral/left to the dorsal/right half. This change reflects an asymmetry in the lengthening of the cycles in the animal cap: more dorsally than ventrally, and more on the right than on the left. The possible significance of the results for the timing of gastrulation and for the pattern of the future embryo is discussed.
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    Development genes and evolution 192 (1983), S. 228-233 
    ISSN: 1432-041X
    Keywords: Cell fusion ; Oogenesis ; Somatic nurse cells ; Dipteran insect
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    Topics: Biology
    Notes: Summary Formation of the oocyte-nurse chamber complex in the cecidomyid insectMycophila speyeri was studied in situ and in vitro by electron microscopy and time-lapse cinemicrography. At the end of the oogonial divisions each oogonium passes through a mitotic division with incomplete cytokinesis. This division gives rise to two sister cells, a prospective nurse cell and the oocyte, which remain connected by an intercellular bridge. In two phases of nurse chamber formation, first four and then (usually) one or two ovarian cells of mesodermal origin fuse with the prospective nurse cell. This results in a syncytial nurse chamber containing one germ-cell-derived nucleus and a varying number of mesoderm-cell-derived nuclei. In two subsequent fusion steps, two mesodermal cells fuse with the oocyte, giving rise to an oocyte containing one large and two small nuclei. Thus, four fusion steps lead to the formation of the complete oocyte-nurse chamber complex. Characteristics of the cell fusions are: (1) in each case one or more somatic cell(s) fuse with a germ-line cell and (2) cell contact between the fusing cells is established by the somatic cell, which approaches the germ-line cells.
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    Development genes and evolution 192 (1983), S. 248-255 
    ISSN: 1432-041X
    Keywords: Morphogenesis ; Ooplasmic segregation ; Polar Lobe ; Cell surface ; cytochalasin B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the eggs ofSabellaria alveolata specific morphogenetic determinants are segregated into the vegetal part of the egg which is constricted off to form a polar lobe during the first cleavages. Segregation is supposed to take place during meiosis. In this paper we describe the appearance of a patch of small blebs at the vegetal pole of the eggs after both the first and the second meiotic division and after the first cleavage, as assessed by scanning electron microscopy. We investigated the possible functional relationship between the segregation process and the modulation of the surface architecture at the vegetal pole by treating the eggs with cytochalasin B during meiosis. As a result, both the appearance of the blebs and the development of lobe-dependent structures in the larva are suppressed. From this result it is argued that cortical processes at the vegetal pole are likely to be involved in the segregation of morphogenetic determinants.
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    Development genes and evolution 192 (1983), S. A3 
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    Development genes and evolution 192 (1983), S. 8-12 
    ISSN: 1432-041X
    Keywords: Determination ; Mesoderm ; Dorsal marginal zone ; Cynops
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stepwise process of the formation and determination of mesoderm inCynops pyrrhogaster was analyzed. The presumptive ectoderm (PE) of the early gastrula was transformed into mesoderm within 12 h when transplanted into the upper half of the dorsal marginal zone of the same stage. The self-differentiation capacity and the neural-inducing activity of this newly mesodermized PE (MPE) were examined by both isolation and sandwich cultures. The MPE showed self-differentiation for notochord and muscle in the isolation culture. In the sandwich culture, the MPE made contact with the PE of the successive gastrula stages. The MPE was capable of inducing neural tissues even in the PE of the mid-gastrula, which has high neural competence but loses it within a short period of 6 h. These results show that firstly the mesodermization of the PE is completed within 12 h and secondly both the self-differentiation capacity and the neural-inducing activity are established immediately after the mesodermization of the PE.
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    Development genes and evolution 192 (1983), S. 21-27 
    ISSN: 1432-041X
    Keywords: Vitamin A (Retinoic acid) ; Chick embryo ; Integument Morphogenesis ; Ptilopody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Intra-amniotic injection of 125 μg of retinoic acid to 10-day old chick embryos causes the formation of feathers on the scales of the anterior face of the tarsometatarsus. The early effects of retinoic acid (RA) on the chick foot integument have been studied between 12 h and 72 h following RA injections by two methods. Firstly, sequential fixation in glutaraldehyde and then osmium tetroxide to follow the early changes at the macroscopical and ultrastructural levels. Secondly, sequential grafts of contralateral samples on to chorioallantoic membrane (CAM) of nontreated chick embryos to test their morphogenetic performance and to determine the minimum time for RA to take effect. Results show that during the first 24 h RA causes morphological changes of both epidermal and dermal cells in almost half of the injected embryos. In particular, the dermal-epidermal junction is transformed from scale-type into feather-type. However, the development of grafted samples shows that feather morphogenesis is irreversibly undertaken only 24 to 48 h after the treatment. At this stage, roundish feather-like placodes are formed instead of the normal rectangular, scale placodes. The scales, the formation of which has been temporarily inhibited, resume their development between 48 h and 72 h after the the injection, proximally to the feather buds, so that feathers are finally carried by the distal tips of the scales.
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    Development genes and evolution 185 (1978), S. 127-136 
    ISSN: 1432-041X
    Keywords: Ommochromes ; 3-OH-kynurenine ; Pigment granules ; Ephestia kühniella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Imagines der Mutantealb vonEphestia wurden auf Metaboliten der Tryptophan→Ommochromreaktionskette untersucht. Zum Vergleich wurden der Wildtyp und die Mutantewa herangezogen. Die Analyse beschränkte sich auf das Ovar und den Kopf. 2. alb-Köpfe haben mit 14 μmol/g Frischgewicht mehr als das Dreifache der im Wildtyp gemessenen 3-OH-Kynureninkonzentration (4 μmol/g Frischgewicht). Dagegen ist die Ommochrommenge beialb auf etwa 1% reduziert. Das Ommochromspektrum ist jedoch mit dem des Wildtyps identisch. Die Mutantewa enthält im Kopf keinen der analysierten Tryptophanmetaboliten. 3. Die Ovarien aller drei Stämme enthalten dieselbe Konzentration an 3-OH-Kynurenin (1 μmol/g Frischgewicht). Ommochrom kommt in diesem Organ nicht vor. 4. Die Befunde sprechen dafür, daß es mindestens zwei verschiedene Formen der 3-OH-Kynureninakkumulation gibt. Die möglicherweise zugrunde liegenden Mechanismen werden diskutiert.
    Notes: Summary 1. Metabolites of the tryptophan→ommochrome pathway were examined in adults of the mutantalb ofEphestia. The mutantwa and the wild type were analysed for comparison. The investigation was restricted to head and ovary. 2. In thealb head, the concentration of 3-OH-kynurenine was more than three times higher than that in the wild type head. The quantity of ommochromes inalb heads is reduced to 1% of that in the wild type, but the ommochrome spectra are identical. Thewa head fails to accumulate demonstrable amounts of any of the analysed metabolites. 3. The ovaries of all three strains contain identical concentrations of 3-OH-kynurenine. Ommochromes are absent from this organ. 4. The results indicate that different mechanisms for the accumulation of 3-OH-kynurenine may exist in different tissues.
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    Development genes and evolution 185 (1978), S. 195-200 
    ISSN: 1432-041X
    Keywords: Vitamin A (retinoic acid) ; Chick embryo ; Integument morphogenesis ; Ptilopody
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Injection of retinoic acid (3×62.5 μg or 3×125 μg) into the amniotic sac of chick embryos between 10 and 12 days of incubation resulted in the formation of club-shaped feathers within the feather tracts, and the development of feathers in the scale-forming areas of the feet. The latter finding is interpreted as caused by a disturbance of the tissue interactions which occur in the skin of the feet at this time.
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    Development genes and evolution 185 (1978), S. 185-193 
    ISSN: 1432-041X
    Keywords: Coelenterates ; Hydra attenuata ; Nerve-cell-types ; Distribution in ecto- and endoderm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Polyps ofHydra attenuata Pall. were subdivided into four axial fragments (I–IV) of about identical length. Ecto- and endoderm of each of these fragments were separated from each other and dissociated according to the technique of David (1973). Each preparation was qualitatively and quantitatively examined as to its content of nerve cells. The presence of 11 different types of nerve cells (Tardent and Weber, 1976) could be confirmed. While multipolars (M1, M2), symmetrical bipolars (B1, B2) and unipolars (U1, U2) were found in both layers, asymmetrical bipolars (B3–7) are limited to the endoderm (Fig. 1), which, as a whole, contains fewer nervous elements than the ectoderm (Fig. 2). The ecto- and endoderm of the tentacles could not be separated from each other and the dissociation was only partly successful. It was, however, possible to ascertain that among the nerve cells present in the tentacles the most numerous are the symmetrical bipolars (B1, B2).
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    Development genes and evolution 185 (1978), S. 201-207 
    ISSN: 1432-041X
    Keywords: Amphibian embryo ; Cell differentiation ; Cell culture ; Tyrosine ; Melanin synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Explants comprising about 15 cells were dissected from various regions of the blastula ofAmbystoma mexicanum and cultured in Barth's medium. By addition of L-tyrosine to the culture medium it was possible to induce melanin synthesis in three different cells types: undifferentiated embryonic cells, mesenchyme cells and nerve cells. Tyrosine was found to act as an inductor in a very low concentration (1 μM). It is suggested that tyrosine serves both as an inductor and as a substrate for melanin synthesis in the amphibian larva.
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    Development genes and evolution 185 (1978), S. 235-248 
    ISSN: 1432-041X
    Keywords: Liver ; Primary culture ; Ultrastructure ; Albumin synthesis ; Xenopus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Electron microscopic analysis of primary cultures derived from larvalXenopus liver has shown that these cells, although they form only two-dimensional aggregates, retain and presumably also develop structural characteristics typical of liver parenchyma cells, such as bile canaliculi with microvilli and epithelial junctional complexes. As judged from structural criteria, primary cultures contain 80–90% hepatocytes. In contrast to the intact tissue, primary cultures showed excessive development of microfilaments, however. Incorporation of labeled amino acids has revealed further that the capacity for protein synthesis is maintained in culture and that synthesis of liverspecific protein albumin is maintained in vitro, even in liver cultures derived from thyrostatic tadpoles. This latter result suggests that initiation of albumin synthesis in the larval liver is probably not dependent upon thyroid hormones but rather reflects the protodifferentiated state of this tissue.
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