Die Rolle von Lokomotion und Morphologie in der Habitatwahl der Rohrs?nger (Acrocephalus)

Ohne Zusammenfassung

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The role of locomotion and morphology in the habitat selection of reed warblers (Acrocephalus)

     

Phylogenetic Comparison of the Photoaffinity-Labeled Benzodiazepine Receptor Subunits

The late evolutionary appearance of the benzodiazepine receptor (BZR) allows an experimental approach for evaluation of the qualitative development of its subunits. Photoaffinity labeling of brain membranes with [3H]flunitrazepam followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography offers a suitable method for tracing the qualitative evolution of the BZR. A systematic comparison of the subunit patterns in fishes, amphibians, reptiles, birds, and mammals revealed that the subunit of 53K is phylogenetically the oldest photoaffinity labeled subunit; whereas it is the only band present in the lungfish and most amphibians, additional bands are apparent in higher tetrapods. In fishes, the evolution of the BZR subunits leads to the loss of the 53K subunit. KD values are discussed in relation to specific subunit patterns. Possible explanations for the observed variation of the subunits are discussed, with special emphasis placed on the possible evolution by gene duplication and subsequent divergence.     

Fate of Cyclic Nucleotides in PC12 Cell Cultures: Uptake, Metabolism, and Effects of Metabolites on Nerve Growth Factor-Induced Neurite Outgrowth

The fate of cyclic AMP (cAMP), dibutyryl-cAMP (Bt2-cAMP), and the (Sp)-isomer of adenosine 3',5'-monophosphorothioate [(Sp)-cAMPS] was studied in the PC12 culture medium by means of HPLC. In the absence of PC12 cells, cAMP and Bt2-cAMP were rapidly degraded by nonspecific esterases and cyclic nucleotide phosphodiesterase both originating from the serum commonly used as a culture medium ingredient, whereas (Sp)-cAMPS was completely stable. Since 5'-AMP, adenosine, inosine, and hypoxanthine appeared in the culture medium after incubation with cAMP or Bt2-cAMP, we have determined their effect on nerve growth factor (NGF)-induced neurite outgrowth. 5'-AMP, adenosine, and inosine were indeed potent agents in producing a potentiating effect on NGF-induced early neurite outgrowth at a concentration of 1 mM. Thus, cAMP metabolites had the capacity to induce an effect that has been described as cAMP-specific. In serum-free culture medium and in the presence of cells, all cyclic nucleotides were taken up by PC12 cells. Uptake was highly correlated with the hydrophobic nature of the compounds, and was accompanied by a simultaneous excretion of metabolites. On incubation with cAMP, NGF had a pronounced effect on the metabolic pattern found in the culture medium. In particular, dephosphorylation of 5'-AMP was specifically enhanced. This effect of NGF on the degradation of cAMP was also apparent when cAMP metabolites were incubated with PC12 cells. Whereas 5'-AMP degradation was greatly increased, NGF had no effect on the metabolism of the other purine compounds.     

Morphologische Aspekte der Habitatwahl von Zugv?geln in einem SW-deutschen Rastgebiet

Zusammenfassung Bairlein (1981) stellte eine Beziehung zwischen Ökologie und Morphologie durchziehender Kleinvögel in einem SW-deutschen Rastgebiet (Mettnau, 47,44 N/09,00 E) fest. Eine neue Analyse der Daten beschäftigt sich speziell mit den morphologischen Aspekten der Habitatwahl. Fangdaten aus 7 Jahren von 32 Arten (Tab. 1), welche die Verteilung der Vögel auf die einzelnen Netze (Abb. 1) und die Fanghöhe in den Netzen betreffen, wurden zusammen mit 36 morphologischen Merkmalen der Arten (Tab. 2) analysiert. Die Auswertungen basieren auf der kanonischen Korrelationsanalyse. Die morphologischen Merkmale wurden aus datenanalytischen Gründen vorher einer Hauptkomponentenanalyse unterzogen (Tab. 2). Als deutliche Beziehung zwischen Ökologie und Morphologie finden wir: Die Fanghöhe in den Netzen hängt mit morphologischen Merkmalen zusammen, die mit der Lokomotionsweise innerhalb des Lebensraums zu tun haben. Häufig und geschickt manövrierende Arten mit geschlitzten Flügeln werden vorzugsweise in den höheren Netzfächern, Arten, die sich sehr viel mit Hilfe der Hinterextremität fortbewegen, hingegen im unteren Netzbereich gefangen (Tab. 3, Abb. 2). Diese Arten weisen sich durch den Besitz gestufter Schwänze, großer Füße, kurzer Schnabelborsten und wenig geschlitzter Flügel aus. Eine undeutlichere Beziehung zeichnet sich zwischen Netzposition (die eine Abfolge von Gebüsch-Waldlebensräumen über Pfeifengras-Seggenzone zu ufernahen Röhrichten charakterisiert, Abb. 1) und dem Flügelschnitt ab (Tab. 3, Abb. 3). Spitzflügeligere Formen, die auch längere Krallen besitzen, werden in den ufernahen Röhrichten, rundflügeligere Arten dagegen mehr in den landseitigen Gehölzen gefangen. Der Flügelschnitt spiegelt nicht nur die Verteilung auf die verschiedenen Habitate, sondern auch unterschiedliche Zugleistungen wider. Spitzflügeligere Arten sind in der Regel Langstreckenzieher. Keine Zusammenhänge konnten zwischen Schnabelbau und Habitatwahl gefunden werden.

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Morphological aspects of habitat selection of small migrating birds in a SW-German stopover site

Summary Bairlein (1981) documented a relationship between the ecology and morphology of avian transients in a SW-German stopover site (Mettnau 47° 44 N/09° 00 E). A reanalysis of these data is concerned with morphological aspects of habitat selection. Data over 7 years from 32 species (Tab. 1) on the distribution of captures in different nets, located in different habitats (Fig. 1) and the height of capture were compared with 36 morphological characteristics using canonical correlation analysis. The morphological parameters were previously subjected to a principal components analysis (Tab. 2) for analytical reasons. The predominant relationships between ecology and morphology were between: the height of capture in the nets and morphological characteristics relevant for locomotion within the habitat. Manoeuvrable species with slotted wings were primarily caught high in the nets whereas species more dependent on the hind limb were caught low in the nets (Tab. 3, Fig. 2). These species were characterized by rounded tails, large feet, short rictal bristles and the lack of notched wings. A less clear relationship was found between the net position (which varied from forest and bush through sedges to the reeds on the bank of the lake) and wing form (Tab. 3, Fig. 3). Species with pointed wings and longer claws were found in the reeds near the shore. Those with more rounded wings were found in the wooded areas. The form of the wings also reflected the migratory performance. Pointed wings were characteristic for long distance migrants. No relationships were found between beak structure and habitat selection.

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16. Mitteilung aus dem MRI-Programm.     

Evidence for the occurrence of the opioid octapeptide dynorphin-(1–8) in the neurointermediate pituitary of rats

Evidence is provided for the existence of the opioid peptide dynorphin-(1–8) in the neurointermediate pituitary of rats. The octapeptide was isolated by immunoadsorption to antibodies directed against porcine dynorphin-(1–13) followed by a variety of chromatographic separation procedures. The identity of the purified material with dynorphin-(1–8) was indicated by the following criteria: comigration with synthetic dynorphin-(1–8) on gelfiltration chromatography and high-performance liquid chromatography systems and liberation of a peptide with the same chromatographic behavior as leucine-enkephalin after sequential cleavage with trypsin and carboxypeptidase B.Radioimmunological estimations revealed that dynorphin-(1–8) is a major dynorphin-related opioid peptide in the pituitary of rats.     

On time dependency of frequency and distribution of chromatid aberrations induced by mutagens with delayed effects. An interpretation

This paper provides a theoretical analysis of pecularities of both the frequency and intrachromosomal distribution of chromatid aberrations observed in the first post-treatment mitosis and induced by clastogenic agents showing delayed effects (S-phase dependent clastogens), as functions of recovery time. The theoretical deductions are based on the following facts: (1) DNA is the target of clastogen action. Lesions induced by clastogens showing delayed effects (e.g. mono- and polyfunctional alkylating agents, ultraviolet light) give rise to aberrations only after interference with the process(es) associated with DNA replication. (2) DNA replication occurs asynchronously with respect to the local involvement in replication of different chromatin regions and according to a highly ordered pattern. (3) Lesions may be removed from DNA (or otherwise modified) by repair processes prior to replication. The removal of lesions from DNA is a time-dependent function.Several possibilities are analysed (i.e. random or non-random distribution of DNA lesions, uniform or locally differing capacities of pre-replicative repair of lesions, uniform or locally differing rates of DNA synthesis) and the frequencies and distribution patterns of chromosome structural changes, as expressed in form of aberration yield-time curves, have been discussed. The theory presented in this paper offers a simple interpretation both of variations of aberration frequency and aberration distribution in dependence on the cell's position within the cell cycle during induction of lesions.It is shown that the intrachromosomal aberration distribution is non-random even if random distribution of lesions and uniform repair rates between chromosome regions replicating at different time periods during S are assumed. Non-random aberration distributions are a necessary consequence of at least two factors: (a) the temporal replication pattern, and (b) the repair activities acting prior to replication. Random distribution of aberrations is only to be expected for the most simplified situation (random distribution of lesions along the DNA and equal transformation probabilities of a given kind of lesion into aberrations) when no loss of lesions prior to replication takes place (no pre-replicative repair) and cells treated with the mutagen during G1 are analysed.     

Analysis of bromine-oxidised dextran by 13C-n.m.r. spectroscopy

Dextran T 10, elaborated by Leuconostoc mesenteroides NRRL B-512, was oxidised with aqueous bromine at pH 7.0. The resulting oxodextran and its methoximated derivative were analysed by ¹³C-n.m.r. spectroscopy. The total amount of keto groups and their positions were established. Assignments of the ¹³C signals were made by referring to spectra of the corresponding methyl glucosiduloses and an oxodextran having most of the carbonyl groups at position 3 of the glycopyranosyl residues. In accordance with the mechanism for bromine oxidation of mono- and di-saccharides, the glucopyranosyl residues of dextran were oxidised mainly at C-2 and C-4. Over-oxidation resulted in a small proportion of acidic, ring-cleavage products.     

Identification and structural characterization of further DNA elements in the potato and pepper genomes homologous to the transposable element-like insertion Tst1

Summary The molecular cloning and nucleotide sequence of elements from potato and pepper that are related to the recently identified Tst1 element are described. Sequence analysis reveals considerable conservation of sequences internal to both the Tst1 element and two of the related elements identified here. In six potato clones analysed, the II by inverted repeat first identified in the Tst1 element is conserved. Several of the elements are flanked by an 8 by direct repeat. DNA fragments which were amplified from several pepper genomes by polymerase chain reaction (PCR) amplification using the inverted repeat as sequence primers also display considerable conservation of sequences internal to the Tst1 element. These data further support the possibility that Tst1 is a non-autonomous transposable element and that Tst1 might be the first example of a transposable element which occurs in several genera of solanaceous plants.     

(4S)-4-amino-5,6-heptadienoic acid (MDL 72483): A potent anticonvulsant GABA-T inhibitor

(4S)-4-Amino-5,6-heptadienoic acid ((S)--allenyl-GABA; MDL 72483) is a potent inactivator of brain GABA-T in mice; (ED₅₀ (i.p.)=60 mg·kg^–1; ED₅₀ (oral)=70 mg·kg^–1). Its anticonvulsant effects against 3-mercaptopropionic acid (MPA)-induced seizures in mice is related to the elevation of whole brain GABA concentrations: The mentioned doses of MDL 72483 which cause a decrease of GABA-T activity by 50%, produce within 5 h after dosing an increase of GABA concentration by about 3 mol·g^–1, and protect 50% of the mice against seizures in this model of presynaptic GABA deficit. When given orally MDL 72483 is about five times more potent than vigabatrin ((4R/S)-4-amino-5-hexenoic acid) a known antiepileptic GABA-T inhibitor. Complete protection was achieved with a dose of 150 mg·kg^–1. Similar to vigabatrin, MDL 72483 does not protect significantly against metrazol-induced convulsions. However, at a dose of 300 mg·kg^–1, the time elapsing between metrazol administration and onset of convulsions was prolonged by a factor of 3.4. Oral administration of MDL 72483 for up to 19 days at a daily dose of 91–96 mg·kg^–1 did not produce any obvious behavioral changes in mice, nor was the ED₅₀ of the drug in MPA-seizure tests significantly altered by the pretreatment. These observations indicate that MDL 72483 is a promising drug for the treatment of certain epilepsies.Special issue dedicated to Dr. Eugene Roberts.