Bestimmung des Heterochromatisierungsstadiums beim white-Positionseffekt mittels r?ntgeninduzierter mitotischer Rekombination in der Augenanlage von Drosophila melanogaster

Summary Position-effect variegation of eye pigmentation in the examined Dp(1;3)N ^264-58 females is due to an insertion of a X-chromosome section including the white-locus into the proximal heterochromatic region of the third chromosome. The light and dark pigmented areas have a cell lineage basis (Fig. 2). Flies bearing the w ⁺-duplication had two X-chromosomes marked with w ^a lz ⁵⁰ e and w ^a rb rux ² respectively (Fig. 3). X-ray induced mitotic recombination in presumptive eye cells of larvae resulted in w ^a lz ^50e /w ^a rb rux ² twin mosaic spots in the adult eyes. After young larvae were treated twin spots appeared, which had one partner light colored and one dark. Such combinations were rarely found after older larvae were treated. Treatment of young larvae in addition produced twin spots with one or both partners variegated (Figs. 5 and 6). Sometime after the stage at which younger larvae were treated and before the stage at which older larvae were treated the translocated w ⁺-gene in each cell was determined for function or no function. As a result the progeny of each of these cells synthesized pigment or not during the pupal stage. At a temperature of 25.5° C the developmental phase during which determination, i.e. heterochromatization of the white gene, takes place, begins not earlier than 39 hours after egg laying and ends about 8 hours later (Fig. 7). In females heterozygous for the short arm of the heterochromatic Y-chromosome linked distally to the X-chromosome (Y ^S X/X) one twin spot partners is homozygous for this arm (Y ^SX/Y^S X), the other lacks it (X/X; Fig.4a). The Y ^SX/Y^S X-partner were more frequently dark pigmented than the X/X-partners (Tables 3 and 4). This shows that heterochromatization of the translocated w ⁺-genes is markedly influenced by the genotype of the single cell. When two genotypes with varied amounts of heterochromatin were compared (Fig. 4) no difference in the phases of heterochromatization could be observed (Table 5). Therefore, when position-effect variegation is modified by varying the amount of heterochromatin in the genome the modification is probably not due to a shift in the phase of heterochromatization.

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Vorgelegt von E. Hadorn     

Farbstoffgehalt und Grösse der Augen bei verschiedenen Mutanten von Drosophila melanogaster

Zusammenfassung Quantitative Untersuchungen über den Farbstoffgehalt der Drosophilaaugen haben schon wiederholt gezeigt, daß die Werte bei bestimmten Mutanten von der Erwartung abweichen. So fand man regelmäßig bei den rotäugigen Mutanten v bzw. cn weniger Pterin und bei der braunäugigen Mutante bw weniger Ommochrom als bei Wildfliegen.Wir haben diese Befunde zunächst mit Hilfe einer vereinfachten Extraktions- und Meßtechnik nachgeprüft und bestätigt. Die genauere Analyse ergab dann aber, daß das Farbstoffdefizit der Mutanten v, cn und bw lediglich darauf beruht, daß diese Tiere kleinere Augen haben als die Wildfliegen. Die Augenverkleinerung ist jedoch nicht, wie gelegentlich vermutet wurde, die Folge einer polyphänen Wirkung der Gene v, cn und bw, sondern nur eine besondere Eigenschaft bestimmter Fliegenstämme, die heute in fast allen Laboratorien gehalten werden.Die Erscheinung selbst beruht auf der Wirkung augenverkleinernder Modifikationsgene, die bei diesen Stämmen zufällig mit den Farbgenen gekoppelt sind, durch geeignete Kreuzungen aber eliminiert werden können. Unsere so erhaltenen neuen v-, cn- und bw-Stämme besitzen nicht nur ebenso große Augen wie die Wildfliegen, sondern enthalten auch die theoretisch erwarteten Mengen an Augenfarbstoffen. Der Zusammenhang zwischen der Größe der Augen und ihrem Farbstoffgehalt hat u. a. zur Folge, daß die Männchen, die ja stets kleinere Augen haben als die Weibchen, bei allen Mutanten weniger Augenpigment besitzen als jene.Der Farbstoffgehalt der Augen hängt außerdem von der Zucht-temperatur ab. Fliegen, die sich bei 18° C entwickeln, besitzen weniger Pterin aber mehr Ommochrom als solche, die bei 26° C aufgezogen werden. Auch die Melaninsynthese im Integument der Tiere wird durch Temperaturerniedrigung begünstigt; aus 18°-Zuchten stammende Fliegen sind deutlich dunkler als die entsprechenden 26°-Tiere.     

Analyse der physiologischen Bedingungen des Vermehrungswachstums männlicher Keimzellen von Drosophila melanogaster

Summary 48 h old testis were implanted into different adult hosts. In virgin females the germ cell multiplication is lower than in both mated females or in males. However in all host types the differentiation into spermatids beginns at the same time as in situ.The role of the different adult host glands in male germ cell development was investigated. Through inactivation of such glands in mated females or implantation of extra glands in virgin hosts was demonstrated, that not the adult Corpus allatum but the Median Neurosecretory Brain Cells (MNBC) are responsable for this germ cell multiplication.Adult host provided with larval Ring gland or pupal host accelerate the germ cell differentiation but not the germ cell multiplication of implanted testis. This acceleration would be much higher if the normal development of the germ cells in adult hosts were due to rests of pupal hormons in this milieu.The nutritive conditions of the host play a very important role in germ cell multiplication. The testis implanted in castrated females or females injected with casein hydrolisate show a higher number of developing germ cells. The MNBC controll the protein metabolism (assimilation) but are only indirectly responsable for the germ cell multiplication; the multiplication is a consequence of the autonomous protein synthesis of the germ cells themself.The growth of other imaginal discs in adult hosts are discussed in the light of these results.

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Herrn Prof. Dr. E.Hadorn bin ich zu Dank verpflichtet für die kritische Diskussion dieser Arbeit, Herrn Dr. R.Nöthiger und Herrn W.Gehring für die Hilfe bei der Abfassung des deutschen Textes.     

über die Auslösbarkeit von Temperatur-modifikationen wÄhrend der Embryonalentwicklung von Drosophila melanogaster Meigen

Ohne Zusammenfassung     

Wirkungen von L-glutaminsäure auf grösse und puff-muster der Larvalen Speicheldrüsenchromosomen von Drosophila melanogaster in vivo

The ratio DNA: RNA in the dry substance of Drosophila melanogaster larvae changes when L-glutamic acid is added to the substratum. The number of cells in the salivary glands is not affected (Fahrig et al., 1967). The present paper deals with the effect of this altered ratio on the puffing pattern of the salivary gland chromosomes.Compared to controls of the same game age, glutamic acid fed prepupae younger than 15 min have five additional puffs. In all, 98 pairs of homologous puffs were studied. In 54 of these, size differences were tested statistically; in the glutamic acid series, 20 puffs were larger and 18 smaller than in the controls whereas 16 had the same size. Size reduction was stronger in the more prominent puffs. In prepupae reared at lower temperatures, chromosomes were significantly longer. Glutamic acid causes a significant increase in chromosome width. Combined measurements of both effects were made by determining the surface area of tested segments. Lowering the temperature adds higher size classes, whereas addition of glutamic acid causes a significant shift of the distributional peak towards the higher size classes. This excludes the possibility of an additional replication cycle. In salivary glands of glutamic acid fed prepupae the majority of nuclei have reached the highest degree of polyteny, which in controls is never found at 25° C but sometimes at 18° C. The agent causing both additional puffing and enhanced growth is effective only via the alimentary tract of the larva.     

Die puff-Musterfolgen der Speicheldrüsenchromosomen aus wanderlarven und vorpuppen von Drosophila melanogaster in vitro

Late larval salivary glands of D. melanogaster of an exactly defined developmental stage (VP 0, i.e. prepupae ot later than 15 min after formation of the puparium) are cultured under sterile conditions in three standard media for insect tissue culture and in Ringer solution. In chromosomes II and III, variations in puff number and size are the same in vivo and in vitro, and almost all changes in puffing pattern are very similar to those appearing in normal development. They are the same in the four media. No additional puff is ever induced due to the medium. By contrast, salivary gland chromosomes from larvae of the late third instar before pupation do show different alterations in vitro than in vivo. This points to a threshold in the course of the puffing pattern between puff stage 8/9 and 10/11. The appearance of a substance causing prepupal changes in puffing is strictly correlated with the formation of the pupanium and the beginning of the intermoult phase in the prepupa. Comparing the results of the experiments it can be stated that the new control system is not based solely on the absence of ecdysone, but also on the existence of another inducer. Immediately after puparium formation the control by ecdysone is still active, together with the control by the supposed inducer. Later, control by ecdysone respectively by the puffs of the ecdysone cycle is substituted by the new control system, up to the next moult. As far as the chemical nature of the puffing inducer in the intermoult phase is concerned, further investigations are necessary.     

Experimentelle Untersuchungen über Hitzemodifikationen des Flügels von Drosophila melanogaster

Ohne ZusammenfassungMit Unterstützung der China Foundation und der Alexander von Humboldt-Stiftung.D₇.     

Die Häufigkeit der Telomeren bei Drosophila melanogaster in Abhängigkeit von verschiedenen Auslesebedingungen

Zusammenfassung Aus einer Laborpopulation wurden durch verschiedene Selektion Linien abgeleitet, in denen die Häufigkeiten der Telomeren an den Chromosomenarmen 3L und 3R ausgezählt wurden. Die beobachteten Häufigkeiten entsprachen in der Regel den beim Hardy-Weinberg-Gleichgewicht zu erwartenden. Die Häufigkeit der Telomeren am Chromosomenarm 3R wird von Art und Richtung der Auslese beeinflußt, wobei sich typische, von den Auslesebedingungen mitbestimmte Gleichgewichte einstellten. Terminale Adhäsionen der Chromosomenarme 3L und 3R wurden häufiger bei vorhandenem Telomer beobachtet.Die Ergebnisse lassen den Schluß zu, daß Vorhandensein und Fehlen von Telomeren Bestandteil der genetischen Variabilität der Population ist und daß die Telomeren der Auslese direkte Ansatzpunkte liefern.

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Frequency of telomers in Drosophila melanogaster dependent on different modes of selection

Summary The frequencies of telomers were counted in chromosomes 3L and 3R in several strains of Drosophila melanogaster kept under different selection pressures for many generations. Observed frequencies were in most cases in good agreement with frequencies expected from Hardy-Weinberg-equilibria. Mode and direction of selection affected the frequencies of telomers on chromosome 3R. Equilibria of the telomer-structures were determined to a certain degree by different selection procedures. Terminal adhesions of 3L and 3R were more frequent when telomers were present.The main conclusion is that presence or absence of telomers are part of the genetic variability of populations, and that telomer frequencies are affected by selection in much the same way as other adaptive chromosome polymorphisms.

     

Heterosis × nutrition interaction in Drosophila melanogaster

Summary The relationship between heterozygosity and the expression of heterosis at two different nutrition levels was investigated using Drosophila melanogaster. Average daily egg production and egg hatchability were measured in two parental strains and in F₁, F₂ and reciprocal backcross generations. Heterosis was more pronounced in the poor nutritional conditions. Two electrophoretic markers used to estimate the level of heterozygosity in F₂ and backcrosses revealed an excess of heterozygous genotypes. Quantitative genetic effects (an additive line effect and individual and maternal heterosis) were estimated for both traits in the two environments. Although this model gave a reasonable fit in most cases, some epistatic interaction would have to be invoked in order to explain fully the results.     

Die Lage des Aufnahmeorganes für die Schlupfperiodik von Drosophila

Zusammenfassung Der Ort, dessen tagesrhythmisch wechselnde Beleuchtung zur Schlupfperiodik von Drosophila führt, liegt in der Kopfregion der Puppe.     

Untersuchungen zur Struktur und Funktion des Lampenbürsten-Y-Chromosoms in der Spermatogenese von Drosophila

Incorporation studies with radioactive precursors have shown that the lampbrush-like loops of the Y-chromosome in the spermatocytes of Drosophila hydei contain axial DNA and actively synthesize RNA. Uridin-incorporation, at least in some of the loops, appears to be polarized. In most of the loops, the amount of the label increases with incubation time. Studies of the life cycle of spermatocytes indicate that labeled RNA is stored in the loops for about 20 to 30 hours, while the loops themselves persist for about 120 hours. Following incubation with labeled amino-acids, an uptake of labeled proteins from the cytoplasm into the nucleus was observed. The labeled nuclear proteins apparently leave the nucleus within a few hours, without long-term binding to the Y-structures, for even a 40-hour-incubation does not result in preferentially labeled Y-structures. These data, along with data on the action of antimetabolites, suggest that the Y-structures are dynamic structures: Their form seems to be maintained by an equilibrium between the accumulation and outflow of matrix material surrounding the DNA axis. The possible role of the functional structures of the Y-chromosome for messenger utilization in the postmeiotic stages of spermiogenesis is discussed.     

Einfluss der Pufferlösung auf die färberische Bestimmung des Umladungsbereiches von Gewebselementen

Zusammenfassung Bei Behandlung histologischer Schnittpräparate mit gepufferten Farblösungen erfolgt neben der Bindung von Farbstoffionen auch eine Adsorption von farblosen Ionen des Puffergemisches. Der färberisch bestimmte Umladebereich wird hierdurch mehr oder weniger stark verschoben und stellt daher lediglich einen Äquivalentwert dar.Zur Durchführung der Untersuchungen standen Mittel der Deutschen Forschungsgemeinschaft zur Verfügung.