Satelliten-Telemetrie beim Wei?storch (Ciconia ciconia) auf dem Wegzug — eine Pilotstudie

Zusammenfassung (1) 1991 konnten erstmals 4 mit Kleinsendern ausgerüstete Weißstörche mit Hilfe der Satelliten-Telemetrie auf Teilstrecken ihres Wegzugs bis zu 46 Tage lang verfolgt werden. Die japanischen Sender betrugen nur etwa 2 % des Körpergewichts der Vögel; die Ortung erfolgte durch das ARGOS-System. Die Versuchsvögel zeigten völlig normales Zugverhalten. — (2) Drei der in Brandenburg und Sachsen-Anhalt markierten Vögel waren Ostzieher und konnten über Strecken von etwa 640–4700 km verfolgt werden, 1 Storch bis zur ägyptisch-sudanesischen Grenze. Ein Westzieher konnte rund 1400 km bis zu den Pyrenäen geortet werden. — (3) Die Vögel wanderten individuell recht verschieden. 2 zogen weitgehend kontinuierlich bis in den Sudan bzw. zu den Pyrenäen, die anderen legten längere Pausen ein. Die ermittelten Zugstrecken verliefen recht geradlinig; Richtungsänderungen erfolgten vor allem an der Donau, den Karpaten, am Mittelmeer und auf der Sinai-Halbinsel. Tagesetappen betrugen mindestens bis zu 370 km, in einem Fall in 21 Tagen durchschnittlich 224 km/Tag. Die Zuggeschwindigkeit lag in der Größenordnung von 30–90 km/h. — (4) Verbesserte Sender mit längerer Lebensdauer und mehreren Ortungen pro Tag dürften es bald ermöglichen, individuelle Wanderrouten von Weißstörchen und anderen Großvögeln praktisch lückenlos zu ermitteln. Begleitmannschaften werden zudem die Zug- und Rastökologie mit Sendern ausgerüsteter Vögel mit erfassen können. Damit dürfte der Vogelschutz auf dem Zug eine neue Dimension gewinnen.

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Satellite tracking of White Storks during the autumn migratory period — a pilot study

Summary (1) In 1991 parts of the routes of White Storks migrating in autumn could be recorded for the first time by satellite tracking. Four individuals could be followed for up to 46 days. Transmitter weight accounted for only about 2 % of body mass. Locations were obtained by the ARGOS system. Migratory behaviour of the experimental birds appeared to be absolutely normal. — (2) The birds were equipped with transmitters in eastern Germany. Three of them followed the eastern migration route and could be tracked from 640 up to 4700 km, the latter reaching the borders of Egypt and Sudan. A western migrant could be followed over a distance of about 1400 km towards the Pyrenees. — (3) Migration showed considerable individual variation. Whereas in two birds migration was largely continuous towards the Sudan and the Pyrenees, respectively, the other birds rested for longer periods. The tracked migration routes were fairly straight. Marked directional shifts occurred towards the Danube valley, at the Carpathian mountains, the Mediterranean and on the Sinai. Capacity per day was at least 370 km. One bird covered 224 km/day on average during a period of 21 days. Migration speed ranged in the magnitude of 30–90 km/h. — (4) Improved transmitters with increased lifetime giving several locations per day will presumably allow to record migration routes of White Storks and other large birds more completely in the near future. Escorts should then be able to closely analyse the ecology of migration and staging of their test birds. These possibilities may give a new dimension to bird conservation measures during migration.

     

Effects of deletion of the prolactin receptor on ovarian gene expression

Prolactin (PRL) exerts pleiotropic physiological effects in various cells and tissues, and is mainly considered as a regulator of reproduction and cell growth. Null mutation of the PRL receptor (R) gene leads to female sterility due to a complete failure of embryo implantation. Pre-implantatory egg development, implantation and decidualization in the mouse appear to be dependent on ovarian rather than uterine PRLR expression, since progesterone replacement permits the rescue of normal implantation and early pregnancy. To better understand PRL receptor deficiency, we analyzed in detail ovarian and corpora lutea development of PRLR-/- females. The present study demonstrates that the ovulation rate is not different between PRLR+/+ and PRLR-/- mice. The corpus luteum is formed but an elevated level of apoptosis and extensive inhibition of angiogenesis occur during the luteal transition in the absence of prolactin signaling. These modifications lead to the decrease of LH receptor expression and consequently to a loss of the enzymatic cascades necessary to produce adequate levels of progesterone which are required for the maintenance of pregnancy.     

Aprotinin uptake in the proximal tubules in the rat kidney. II. Uptake site relative to glomerulus

Glomerular filtration rates in whole kidney and in outer, middle and inner cortical zones have previously been estimated by measuring the amount of iodinated Aprotinin, filtered and taken up in the first two thirds of the proximal convoluted tubules, in part positioned more superficial than the parent glomerulus. Thus, an appreciable amount of the absorbed Aprotinin may be located superficial to its filtration site and lead to an underestimate of glomerular filtration in deep cortical layers. Therefore, in this study we have measured the distance from the glomerulus to the center of proximal convoluted tubular ball and the site of Aprotinin uptake. Measurements were made on photos of Microfil-injected tubules and on camera lucida drawings of tubular transections from autoradiographs of nephrons containing both Microfil and iodinated Aprotinin. Both techniques showed that the center of the tubular ball was localized more superficial in all cortical layers. The average distance, in percent of cortical thickness, from all proximal convoluted tubular transections to the parent glomerulus was 9% in deep and 13% in middle and superficial cortex. Corresponding distances for tubular transections containing Aprotinin were 7 and 12%. Grain density in five reconstructed proximal convoluted tubules showed a continuous and exponential fall of Aprotinin along the uptake segment. The results may be used to estimate single nephron filtration rate from Aprotinin uptake and glomerular density in outer, middle, and inner cortex.     

Light-enhanced dark respiration in leaves and mesophyll protoplasts of pea in relation to photorespiration,respiration and some metabolites content

The respiration rate of leaves and mesophyll protoplasts of pea (Pisum sativum L.), from plants which were previously kept in darkness for 24 h was doubled following a period of photosynthesis at ambient level of O₂ (21 %), whereas the low level of O₂ (1 % and 4 % for leaves and protoplasts, respectively) reduced this light-enhanced dark respiration (LEDR) to the rate as noted before the illumination. Similarly to respiration rate, the oxygen at used concentrations had no effect on the ATP/ADP ratio in the dark-treated leaves. However, the ATP/ADP ratio in leaves photosynthesizing at 21 % O₂ was higher (up to 40 %, dependence on CO₂ concentration in the range 40–1600 1 dm⁻³) than in those photosynthesizing at 1 % O₂ or darkened at air (21 % O₂). Also, at 1 % O₂ the accumulation of malate was suppressed (by about 40 %), to a value noted for leaves darkened at 21 % O₂. The dark-treatment of leaves reduced the ability of isolated mitochondria to oxidize glycine (by about twofold) and succinate, but not malate. Mitochondria from both the light- and dark-treated leaves did not differ in qualitative composition of free amino acids, however, there were significant quantitative differences especially with respect to aspartate, alanine, glutamate and major intermediates of the photorespiratory pathway (glycine, serine). Our results suggest that accumulation of photorespiratory and respiratory metabolites in pea leaves during photosynthesis at 1 % O₂ is reduced, hence the suppression of postillumination respiration rate.