Development of a stable body temperature and growth rates in nestlings of three ground nesting passerines in alpine tundra

Summary The mass gain, feather growth and development of a stable body temperature in nestlings of three ground nesting passerines — the Skylark (Alauda arvensis), Water Pipit (Anthus spinoletta) and Wheatear (Oenanthe oenanthe) — were studied in the alpine meadows of the western Pyrenees. When left together in the nest, individual Skylark nestlings had a stable body temperature of about 39°C by day 5, Water Pipits by day 6–7 and Wheatears by day 7–8. Individual nestlings, taken out of the nest and exposed to low ambient temperatures, could maintain a high body temperature (90% of adult levels) at an age of between 7 and 8 days (Skylark), and 10 and 11 days (Water Pipit and Wheatear, respectively). Feather growth was fastest in Skylarks. As the young in this species sit in exposed nests, early growth of feathers may help to retain heat or exclude solar radiation depending on the ambient conditions. Body mass gain is fastest in Skylarks and slowest in Wheatears and Water Pipits, which correlates with their nesting mode. All three species attain half their fledging weight between 4.2 and 5.0 days, regardless how long they remain in the nest subsequently.

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Zusammenfassung Massenzunahme, Federwachstum und Entwicklung einer konstanten Körpertemperatur wurde bei den Nestlingen dreier bodenbrütender Singvögel in den alpinen Matten der westlichen Pyrenäen untersucht, nämlich bei Feldlerche, Wasserpieper und Steinschmätzer. Wenn die Jungen zusammen im Nest bleiben, erreichen Feldlerchen am 5., Wasserpieper am 6.–7. und Steinschmätzer am 7. bis 8. Tag eine konstante Körpertemperatur von etwa 39°C. Einzelne aus dem Nest genommene und niedriger Umgebungstemperatur ausgesetzte Junge können eine hohe Körpertemperatur (etwa 90% der ad.) im Alter von 7–8 (Feldlerche) bzw. von 10–11 Tagen (Wasserpieper, Steinschmätzer) aufrecht erhalten. Das Federwachstum war bei der Feldlerche am schnellsten. Da bei dieser Art die Jungen in offenen Nestern sitzen, dürfte ein frühes Federwachstum eine hohe Bedeutung für die Isolation des Körpers gegenüber der Umgebung besitzen. Die Zunahme der Körpermasse ist bei der Feldlerche rascher als bei Wasserpieper und Steinschmätzer. Die Hälfte der Körpermasse zum Zeitpunkt des Ausfliegens wird bei allen drei Arten im Alter von 4,2 bis 5,0 Tagen erreicht, unabhängig von der Länge der Nestlingszeit.

     

Untersuchungen über die Wirkung des hydrostatischen Druckes auf das Wachstum von Delesseria sanguinea (L.) Lamour. aus der westlichen Ostsee

Observations on the effect of hydrostatic pressure on the growth of Delesseria sanguinea (L.) Lamour. from the western Baltic Sea.The post-treatment effects of hydrostatic pressures (100–500 atm) on the growth in lenght and breadth of young prolifications of D. sanguinea were studied at 15°C. Growth activity was compared amongst the prolifications separated from the midrib and not separated ones, and cell-viability as influenced by high pressures was also observed under the microscope. Pressure-temperature relationship was investigated, in which the pressure effects on growth were studied at different temperatures (5°–22°C), using prolifications which were previously adapted to corresponding temperatures. Long-termed experiments were also set up to study the capability of pressure adaptation in young leaflets. In this regard the growth activity was measured after long-termed exposure to relatively smaller pressures (20–60 atm).

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Institut für Meereskunde an der Universität Kiel, B. R. D.

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Meinem hochverehrten Doktorvater, Herrn Prof. Dr. Fritz Gessner, zum ersten Wiederkehr seines Todestages am 20.12.1973 gewidmet.     

Die quantitative Erfassungsgrenze in der Histochemie

Zusammenfassung Durch Vergleich licht- und elektronenmikroskopischer Befunde am Nebennierenmark wird als praktische Erfassungsgrenze für Catecholamine 10^–11g Adrenalin pro Zelle ermittelt. Das entspricht einer Konzentration im Zytoplasma von 1,0%. Diese Konzentration wird auch als Verdünnungsgrenze in Modellversuchen festgestellt. Aufgrund theoretischer Überlegungen wird dargelegt, daß 10^–11 bis 10^–12g/Zelle allgemein die für eine beliebige histochemische Reaktion notwendige Konzentration darstellt.

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Summary Comparing light and electron-microscopical data from adrenal medulla, the identification limit for catecholamines has been calculated to be in the order of 10^–11g adrenaline/cell. This is equivalent to a concentration of 1,0% adrenaline/cell which has been found to be the dilution-limit in model experiments, too. On the basis of theoretical calculation it has been demonstrated that 10^–11–10^–12g/cell is the concentration needed for any histochemical reaction.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Quantitative DNS-Bestimmungen von Ameisenhirnzellen

Zusammenfassung Gehirnzellen von Myrmica laevinodis-Arbeiterinnen wurden Feulgengefärbt und dabei 1–6 oder 15 Std im Schiffschen Reagens behalten. Die Farbintensität wurde mikrospektrophotometrisch bestimmt. Die Tiere des einen Nestes zeigten ein Extinktionsmaximum nach 1 Std Aufenthalt im Schiffschen Reagens, die eines anderen Nestes nach 5 Std. Die Färbedauer ist also ein weiterer Faktor, der bei quantitativen DNS-Bestimmungen zu berücksichtigen ist.

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Quantitative determination of DNA in feulgen stained brain cells of antsI. The effect of the staining duration on the extinction

Summary Brains of adult Myrmica laevinodis (Hymenoptera, Formicidae) workers were Feulgen stained. They were kept in Schiff's reagens for 1 to 6 hours. In specimens from one nest the colour maximum was reached after 1 hour, in others from a different nest after 5 hours. The colour intensity measured by microspectrophotometry depended on the time the brains stayed in Schiff's reagens. This result means that the time of staying in Schiffs reagens is another factor influencing the amount of measurable DNA.

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Die Untersuchung wurde mit Unterstützung durch den Schweizerischen Nationalfond durchgeführt.

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Die Laborantin Frl. Elisabeth Räber trug mit tatkräftiger, selbständiger Arbeit zum Fortgang der Untersuchung bei. Prof. Dr. F. Ruch stellte uns großzügigerweise sein Mikrospektrophotometer zur Verfügung, wofür ich ihm herzlich danke.     

Bemerkungen zu der Arbeit von Charles Marit et Jean Milaire

Ohne Zusammenfassung

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Mit 1 Textabbildung

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Erschienen in Histochemie2, 298–305 (1961)     

Removal of bacteria and nutrient dynamics within the coral reef framework of Curaçao (Netherlands Antilles)

The authors studied removal rates of bacteria and the regeneration of inorganic nutrients in coral reef cavities in the reef slope of Curaçao, Netherlands Antilles. We found that in cavities the hard substratum surface area (=ca 68% of cavity surface area) is 65% covered with sessile filter feeders. The cryptic cavity surface area exceeds the projected surface area of the reef by 1.5–8 times. Consequently, the organisms living in these cryptic habitats have potentially a large impact on pico- and nano-plankton densities and are important in reef water nutrient dynamics. We closed cavities (±70 l volume, 15 m depth) in seven experiments to study changes in bacterial densities and dissolved inorganic nutrients (DIN, DIP, and silicate) over time. Water samples were taken from the middle of the cavity at 5-min intervals, for 30 min, and analyzed for heterotrophic bacterial abundance and nutrient concentrations. After closure, bacterial abundance dropped rapidly. Of the initial bacterial concentration in the cavities, 50–60% had disappeared after 30 min, an average disappearance rate of 1.43×10⁴ bacteria ml^–1 min^–1 (0.62 mg C l^–1 d^–1; or 30.1 mg C m^–2 cavity surface area d^–1). NO_x concentrations increased significantly during the time of closure. Efflux rates varied between 1.02–9.77 mmol m^–2 cavity surface area d^–1. NH₄⁺ and PO₄^3– concentrations were variable and did not show a consistent change over time in the experiments. Comparison of bacterial organic nitrogen disappearance rates and DIN (NO_x+NH₄⁺) release rates suggests that on average only 30–40% of additional sources of N besides bacteria were required to balance the nitrogen budget. This highlights the importance of heterotrophic bacterioplankton as food for cryptic filter feeders on coral reefs. Silicate concentrations significantly decreased after closure with 0.50 mmol m^–2 cavity surface area d^–1, suggesting the net deposition of SiO₄^2– in spicules of cryptic filter feeding sponges. We conclude that coral reef cavities are a major sink for heterotrophic bacteria, a sink for dissolved silicon (DSi), and a source for NO_x. That reef cavities are a source for NO_x suggests strong remineralization and nitrification in cavities with a potential role for sponge-symbiotic microbial nitrification.Communicated by K.S. Sealey     

Diesj?hrige Wiesenpieper(Anthus pratensis) als Helfer am Nest

Summary On 23.7. 1977a colour-ringed first-year Meadow Pipit was observed feeding nestlings of a third brood of more than two-year-old parent Meadow Pipits for at least three times. The first-year Meadow Pipit had hatched about 1.5. 1977 in a nest about 3100m off the place where it helped feeding.On 27. and 28.6. 1978 another first-year Meadow Pipit was observed feeding nestlings of a brood some four times. This first-year Meadow Pipit had hatched about 8.5. 1978 nearly 3400m off the place where it helped feeding. The only adult parent that was seen feeding the brood was a colour-ringed adult male. On 14.6. 1978 a copulation was observed between the adult male and the first-year Meadow Pipit — obviously a female.Evidently there were no close relationships between the first-year Meadow Pipits and the parents of the broods they helped.     

Über die Physiologischen Eigenschaften von Gewebekulturen aus Tumor- und normalem Gewebe vonPicea glauca

Summary In contrast to other plant tumor tissues (crown gall and genetic tumors), that fromPicea glauca can be cultivated in vitro only in the presence of IAA. The auxin requirement for maximal growth of the tumor is appreciably higher (10^–5 g/ml IAA) than that of normal Picea cultures (10^–8 g/ml). A similar marked difference is also found in the ascorbic acid requirement, which is 10^–5 g/ml for neoplastic, but 10^–7 g/ml for normal tissue. The significance of these results for the characterisation and the in vitro growth of plant tumors is discussed.

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Mit 4 Textabbildungen     

Ein Beitrag zum Zusammenhang zwischen Stimme und Atmung bei V?geln

Zusammenfassung Beim nordamerikanischen Abendkernbeißer (Hesperiphona vespertina, Körpergewicht um 60 g) wurde die Atmung bei einer Reihe von Schreckrufen aufgezeichnet. Die Rufe wurden beim Ausatmen ausgestoßen, der Luftstrom war in Pulsationen von 55–60/sec zerlegt. Bei den dazwischen liegenden Einatmungen waren Atemstrom und Atemvolumen im Vergleich zur Ruhe erhöht. Die Einatmungsdauer betrug nur 0,1–0,15 sec, was der Atmung im Flug sehr ähnlich ist.

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Summary In the North American Evening Grosbeak (Hesperiphona vespertina, body weight about 60 g) the respiration was recorded during distress calls. The calls were produced in the expired airstream in pulsations of 55–60/sec. The inspirations lying between the calls had increased tidal volume and airflow velocity relative to rest. The duration of inspiration was only 0,1–0,15 sec, which is very similar to that in flight.

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Issued as N.R.C. No. 10 302.     

Windrichtung und Vegetationsdeckung am Nest der Silberm?we(Larus argentatus)

Zusammenfassung An 1047 Silbermöwen-Nestern auf den Watteninseln Mellum und Memmert wurden 1979/80 ermittelt (Abb. 1): Grenzrichtungen der Vegetationsstände 1–3 (1: Vegetationsstand größter Winkelgröße) und Nest-Zugänge 1–3, ihre Winkelgrößen und mittleren Richtungen. Mehr als 80% der Nester waren zu 40–90% von Vegetation umstanden (Abb. 2). Die Winkelgröße des Gesamtvegetationsstandes betrug auf Mellum 212°, auf Memmert 205° (Tab. 1). Die Nestzugänge hatten eine geringere Winkelgröße als die Vegetationsstände (Tab. 1, Abb. 3). Die Silbermöwe bevorzugte demnach Nestplätze, die von Vegetation schützend umgeben sind. Der Vegetationsstand 1 befand sich bevorzugt auf der westlichen (= Hauptwindrichtung), der Zugang 1 auf der östlichen Nestseite (Tab. 2, Abb. 4). Die Verteilung der Gesamtvegetation zeigte entsprechende Vorzugsrichtungen (Abb. 6). Im Vergleich zu 1979 war 1980 eine Verlagerung der Vorzugsrichtung des Vegetationsstandes 1 um 50–60° von West nach Nord festzustellen (Tab. 2, Abb. 4). Ein Vergleich der mittleren Windrichtungen beider Jahre zeigte eine gleichsinnige Richtungsänderung (Abb. 5). Auf den zwei untersuchten Probeflächen Mellums ließ sich eine Auswahl des Nestplatzes im Hinblick auf Sichtschutz gegen Nachbarn nicht nachweisen (Tab. 3). Die mögliche Funktion der nestumgebenden Vegetation als Wind- und Wetterschutz wird diskutiert.

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Vegetation surrounding Herring Gulls'(Larus argentatus) nests in relation to wind direction

Summary The following measurements were taken for a total of 1047 Herring Gulls' nests on the North Sea islands Mellum and Memmert (West Germany) in 1979 and 1980 (cf. Fig. 1 for terminology): limiting directions, angular sizes, and mean directions of the surrounding vegetation-stands 1 to 3 (1 = vegetation-stand with largest angular size), and of the entrances 1 to 3. For more than 80% of the nests, 40–90% of the circumference were surrounded by vegetation (Fig. 2). The mean angular size of the total vegetation-stand was 212° on Mellum and 205° on Memmert (Tab. 1). The nest entrances had a smaller angular size than the vegetation-stands (Tab. 1, Fig. 3). This shows the Herring Gull's preference for nest sites protected by surrounding vegetation.Vegetation-stand 1 was preferably orientated towards the west (= main wind direction), nest entrance 1 towards the east (Tab. 2, Fig. 4). The distribution of the total vegetation showed corresponding preferred directions (Fig. 6). A comparison of the years 1979 and 1980 revealed a shift of 50°–60°, from west to north, for the preferred direction of vegetation-stand 1 (Tab. 2, Fig. 4). A similar shift could be found for the mean wind direction (Fig. 5). For the two study plots on Mellum, a nest site selection favouring visual isolation from neighbours' nests could not be demonstrated (Tab. 3). The possible function of nest-surrounding vegetation as a shelter against wind and weather is discussed.

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Herrn Dr. Friedrich Goethe zur Vollendung des 70. Lebensjahres gewidmet     

Predator presence may benefit: kestrels protect curlew nests against nest predators

We studied whether the presence of breeding kestrels (Falco tinnunculus) affected nest predation and breeding habitat selection of curlews (Numenius arquata) on an open flat farmland area in western Finland. We searched for nests of curlews from an area of 6 km² during 1985–1993. For each nest found, we recorded the fate of the nest, and the distance to the nearest kestrel nest and to the nearest perch. We measured the impact of breeding kestrels on nest predation by constructing artificial curlew nests in the vicinity of ten kestrel nests in 1993. Curlew nests were closer to kestrel nests than expected from random distribution, eventhough kestrels fed on average 5.5% of curlew chick production. Predation risk by kestrels was lower than predation risk by corvids and other generalist predators, which predated 9% of curlew nests surviving farming practices and an unknown proportion of chicks. Artificial nest experiment showed that nest predation was lower close to kestrel nests than further away suggesting that the breeding association of curlews and kestrels was a behavioural adaptation against nest predation. Thus, the presence of a predator may sometimes be beneficial to prey, and prey animals have behavioural adaptations to these situations.     

Nest sites and breeding success of Baywinged Cowbirds (Molothrus badius)

Summary Molothrus badius nested in a diversity of natural locations (foliage, cavities, palm trees, etc.) and in nest boxes in a study area in Argentina. No other local passerine showed such diversity of nest locations. Nests built by 3 other species of birds were used, but less frequently than holes. Nest piracy was rare. Some successful nest sites were used for 5–6 breeding seasons. Predation affected only 9 % of the nests. The timing of breeding was not earlier for females using nests built by other birds than for those nesting in other locations. The amount of nest building bybadius was similar for most nest sites. I found no significant differences in the incidence of brood parasitism byM. rufoaxillaris andM. bonariensis between different types of nests. Productivity of young forbadius was not higher for nests in structures built by other birds than for nests located elsewhere,

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Neststand und Bruterfolg des Braunkuhstärlings (Molothrus badius)

Zusammenfassung Molothrus badius wird als der nächste nestbauende Verwandte der brutparasitischen Kuhstärlinge betrachtet. Seine Brutbiologie ist daher von besonderem Interesse. In einem Untersuchungsgebiet in Argentinien brütete die Art in einer Vielfalt natürlicher Neststandorte (Laub, Höhlen, Palmen usw.) sowie in Nistkästen. Kein anderer Singvogel des Gebiets wies eine ähnliche Vielfalt an Nistplätzen auf. Alte Nester dreier anderer Arten wurden benutzt, allerdings weniger häufig als Höhlen. Nestokkupation war selten. Einige erfolgreiche Nistplätze wurden 5–6 Brutperioden benutzt. Nestraub betraf nur 9 % der Nester. in alten Nestern anderer Arten brüteten nicht früher als solche in anderen Nestern. Die Investition in den Nestbau war bei den meisten Nistplätzen ähnlich. Das Ausmaß der Parasitierung durchM. rufoaxillaris undM. bonariensis war in allen Nesttypen gleich. Die Jungenproduktion in alten Nestern anderer Arten war nicht höher als in anderen Nestern.

     

Competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, derived by alteration of mating tactics of the former

Interspecific competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, was studied on a rocky shore. Large males (LM: 55–80mm in standard length: SL) and small males (SM: 34–52mm SL) of B. fuscus acted as nest holders and sneakers, respectively, in the early spawning season (July). The sympatric male E. abax (22–33mm SL) was smaller than SM B. fuscus, and synchronically used rocky holes much smaller than those of LM B. fuscus. In this season, aggressions between the two species were rarely observed. In late season (August), as the number of the LM decreased, the SM converted their tactics to nest holding, occupying nests of a sizes similar to those of E. abax. Eviota abax males were dispossessed by SM and shifted their nest sites to cavities between cobbles and sandy bottom, which might be poorer nest sites than rocky holes.     

Histologische Analysen von triploiden Spontanaborten

Zusammenfassung Es werden die histologischen Befunde an 4 triploiden Spätaborten (14.–21. Woche post menstruationem) beschrieben. Es handelt sich um 3 Triploidien (zweimal 69,XXY und einmal 69,XXX) und 1 Mosaik 46,XX/69,XXY (1:1). An allen 4 Placenten ergaben sich typische degenerative hydatidiforme Veränderungen bei einem Entwicklungsstand von 21–31 Tagen post ovulationem (p.o.). In 2 Fällen waren Embryonen vorhanden, die Mißbildungen im Bereich des ZNS und der caudalen Regionen aufwiesen. Der Entwicklungsstand der Embryonen wurde nach äußerlichen Merkmalen mit 28–30 Tagen p.o. bestimmt. Die histologische Analyse deckte einen Differenzierungsstand von 5–51/2 Wochen p.o. auf.

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Histological analysis of spontaneous abortions with triploidy

Summary 4 triploid abortions with an gestational age of 14–21 weeks were analyzed histologically. 3 of them showed true triploidies (two 69,XXY, one 69,XXX), whereas 1 was a mosaic 46,XX/69,XXY (1:1). Hydatidiform degeneration was found in all the placentae. Normal development had been stopped at an ovulational age of 21–31 days. 2 embryos were found and analyzed histologically. They were malformed, mainly in the CNS and in the caudal region. Development of the external features had been stopped at 28–30 days, while histological analysis revealed, that the developmental arrest of the organs occurred at an ovulational age of 5 and 5 1/2 weeks.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Vorgetragen auf dem 2. Kongreß der European Teratology Society, Prag, 23–26. 5. 1972.     

Dark tree cavities – a challenge for hole nesting birds?

Holes provide the safest nest sites for birds, but they are an underutilized resource; in natural forests there are usually more holes than birds that could use them. Some bird species could be prevented from nesting in holes because of their inability to operate in the low light conditions which occur in cavities. As no visual system can operate in complete darkness some nest cavities could be too dark to be useable even by hole‐nesters. Thus, the light conditions within tree cavities could constrain both the evolution of the hole nesting habit, and the nest site choice of the hole‐nesting birds. These ideas cannot be tested because little is known about the light conditions in cavities. We took an opportunity provided by ongoing studies of marsh tits Poecile palustris and great tits Parus major breeding in a primeval forest (Bia?owie?a National Park, Poland) to measure illumination inside their nest cavities. We measured illuminance in cavities at daybreak, which is just after the parents commenced feeding nestlings. Only ca 1% of incoming light reached the level of the nest. Illuminance at nests of both species (median = 0.1–0.2 lx) fell within mesopic‐scotopic range, where colour vision is impaired. Measurements in model cavities showed strong declines in illumination with distance from the entrance, with light levels typically as low as 0.01 lx at 40 cm from the cavity entrance. Thus cavities can be very dark, often too dark for the use of colour vision, and we suggest that ‘lighting’ requirements can affect the adoption of specific nest sites by hole nesting birds. We discuss implications of the findings for understanding the adaptations for hole‐breeding in birds.     

Nesting habitat and nest features of Water Rails Rallus aquaticus and Little Crakes Zapornia parva on large wetlands

ABSTRACT

Capsule: In large and medium wetlands with extended reed beds Phragmites and cattail Typha dominated areas, Water Rails Rallus aquaticus and Little Crakes Zapornia parva show higher differences in nesting sites in contrast with other populations from small and fragmented wetlands, where the ranges of values for environmental variables at nesting sites overlap greatly.

Aims: To investigate the nesting sites and nesting habitats of both species to a fine scale, on medium and large wetlands, to evaluate the potential overlapping of nesting habitat and to compare data with those obtained in small wetlands.

Methods: In the study area, the Fize? Basin, Romania, 17 wetlands, ponds and reed beds ranging from 11.78 to 252.68 ha were investigated. The species were present on 4 wetlands, which were subsequently surveyed for nests. Between April and August 2010–2012, a total of 83 Water Rail and 46 Little Crake nests were found, measured and analysed in terms of nesting habitat and nest features.

Results: Principal component analyses suggest no overlap in nest site selection and a partial overlap in the nest features. An analysis of similarity confirmed significant nest structural differences. A discriminant function analysis highlights the main factors dividing the nest features of both species being: water depth and distance between the nest and a water surface. Little Crakes build their nests in cattail Typha sloped clumps, while Water Rails build their nests near reed Phragmites strains.

Conclusion: In large and medium wetlands, Water Rails nest deep in the reed bed rather than in other types of habitats, contrary to what has been reported for small ponds areas. Little Crakes nest in cattail independently of the size of the wetland where they occur.     

Studies on the population genetics of the ceruloplasmin polymorphism

Summary Phenotype and gene frequencies of the ceruloplasmin polymorphism are reported. In all populations considered here (Germans, Icelanders, Iranians, Pakistani, and Koreans) high frequencies of the allele Cp^B (0.978–0.996) could be observed, whilst the frequencies of the alleles Cp^A (0.003–0.013) and Cp^C (0.000–0.013) are very low.

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Zusammenfassung Die Verfasser berichten über Phänotypen-und Gen-Frequenzen des Coeruloplasmin-Polymorphismus. In allen untersuchten Populationen (Deutsche, Isländer, Iraner, Pakistani und Koreaner) konnten sehr hohe Frequenzen des Allels Cp^B beobachtet werden (0,978–0,996), während die Frequenzen der Allele Cp^A (0,003–0,013) und Cp^C (0,000–0,013) deutlich geringer sind.

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Supported by the Deutsche Forschungsgemeinschaft.     

Etude de la distribution générale des 46 chromosomes dans les cellules humaines en métaphase

Summary This study, based on the square distances of chromosome centromeres from the center of a cell, shows after circular transformation, that the general dispersion of the 46 chromosomes is uniform, except on the periphery of the cell. It is found that the chromosomes taken separately have not a random distribution, but have peculiar positions. In males, chromosomes 1, 13-14-15 and 21–22 tend to lie nearer the middle of the nucleus, while chromosomes, Y, 6-X and 4–5 tend to lie nearer the periphery. In female mitoses the chromosome 13-14-15, 21–22 and 19–20 and 19–20 have a more central position, while chromosomes 4–5, 3, 2 and 16 tend to lie nearer the periphery.

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Prière d'envoyer les demandes de tirés-à-part à cette adresse.     

The effect of pretreatment with cyanide and azide on the rate of X-ray induced mutations in Drosophila

Summary Drosophila males were injected with a 0.008 M solution of potassium cyanide prior to X-radiation with doses varying from 980–2400 r. Compared to the controls, which were only X-rayed, the frequency of sex-linked lethals after cyanide pretreatment was significantly increased in germ cells which formed mature sperm 4–7 days after treatment. A similar enhancing effect on the X-ray induced mutation rate was obtained by pretreatment with sodium azide. The results are tentatively ascribed to an increased production of hydrogen peroxide in the pretreated irradiated germ cells.

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Zusammenfassung Vor einer Röntgenbestrahlung, deren Stärke von 980–2400 r variierte, wurden Drosophila-Männchen mit einer 0.008 Molar Kaliumzyanidlösung injiziert. Es stellte sich heraus, daß im Vergleich zu den Kontrollen, welche nur bestrahlt wurden, die Mutationsrate nach Zyanidvorbehandlung signifikant gesteigert war, und zwar in den jüngeren Geschlechtszellen, welche 4–7 Tage nach der Behandlung reife Spermatozoen gebildet hatten. Eine ähnliche Zunahme der von Röntgenstrahlen induzierten Mutationsrate konnte nach Vorbehandlung mit Natriumazid beobachtet werden. Als ein möglicher Grund für diese Beobachtungen wird ein erhöhter Gehalt an Wasserstoffsuperoxyd in den vorbehandelten, bestrahlten Zellen in Erwägung gezogen.

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With 1 figure in the text.