M?nnchen-überschu? bei Schwarzspechtnestlingen (Dryocopus martius)?

Zusammenfassung Von 1979 bis 1991 wurde auf einer etwa 200 km² großen Mischwaldfläche in Süddeutschland bei 445 Schwarzspechtnestlingen (140 Bruten; Alter der Jungvögel: 14 bis 20 Tage) eine Geschlechtsbestimmung vorgenommen. Das Gesamtgeschlechterverhältnis (0,92 :1 ; alle Daten von 1979 bis 1991 zusammengefaßt) sowie die Geschlechterverhältnisse der Einzeljahre wichen nicht signifikant von einem ausgeglichenen Geschlechterverhältnis ab. Eine statistische Überprüfung aller zum sekundären Geschlechterverhältnis beim Schwarzspecht vorliegenden Literaturangaben ergab ebenfalls in keinem Fall einen statistisch signifikanten Unterschied zwischen den ermittelten Geschlechterverhältnissen und einem Verhältnis von 1:1. Die mehrmals in der Literatur vertretene Meinung, bei Schwarzspechtnestlingen sei ein -Überschuß festzustellen, ist somit nicht länger haltbar.

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Is there a surplus of males in Black Woodpecker nestlings (Dryocopus martius)?

Summary A population of Black Woodpeckers was studied in an area of about 200 km² in southern Germany from 1978 up to 1991. Once a year the nesting trees were visited to record the age and number of young and to ring the nestlings. In 1979 the sex of seven birds (two broods) was determined additionally (crown feathers showing red from tenth day in , bluish-black in — only nape is red). From 1980 onwards the young of all broods censused were sexed (445 birds; 140 broods; age of the birds: 14 to 20 days). In contrast to several studies which had pointed to a -biased secondary sex ratio in the Black Woodpecker, but corresponding to findings in various bird species sexually monomorphic in size, neither the overall sex ratio (0,92 :1 ; pooled data from 1979 to 1991) nor the ratios of single years showed any significant deviations from 1:1. Likewise, we did not find any differences between the sex ratios of Black Woodpecker nestlings reported in the literature and a balanced ratio. For these reasons it is not tenable any longer to speak about a surplus of in Black Woodpecker nestlings.

     

Inhibition of apoptosis prevents West Nile virus induced cell death

Background  

West Nile virus (WNV) infection can cause severe meningitis and encephalitis in humans. Apoptosis was recently shown to contribute to the pathogenesis of WNV encephalitis. Here, we used WNV-infected glioma cells to study WNV-replication and WNV-induced apoptosis in human brain-derived cells.     

Decreased glycogen mobilization during ochratoxicosis in broiler chickens.

Graded doses of pure ochratoxin A (0, 0.5, 1.0, 2.0, 4.0, and 8.0 microgram of toxin per g of feed) were incorporated into a commercial diet which was fed to chickens from hatching to 3 weeks of age, at which time the experiments were terminated. Liver glycogen levels were elevated significantly (P less than 0.05) by 4.0 and 8.0 microgram/g but not lower doses. Glucagon stimulation of glycogen mobilization was inhibited at the same concentrations. Histopathological examination revealed cytoplasmic but not nuclear deposits of glycogen in cells at the periphery of liver lobes. These data demonstrated that ochratoxin inhibited glycogenolysis. Impaired ability to generate glucose from glycogen could account for the increased susceptibility to cold stress previously reported to occur in ochratoxicosis. Based on present and prior observations, it seems possible that ochratoxin induces a syndrome which mimics the glycogen storage disease of type X which is caused by a deficiency in the cyclic AMP-dependent enzyme of the glycogenolytic enzymatic cascade.     

Pharmacological activity of DTPA linked to protein-based drug carrier systems

The chelating agent diethylenetriaminepentaacetic acid (DTPA) inhibits human cytomegalovirus replication. Since chelating agents are known to exhibit anti-cancer effects, DTPA-induced cytotoxicity was evaluated in breast cancer cells (MCF-7) and neuroblastoma cells (UKF-NB-3). DTPA inhibited cancer cell growth in threefold lower concentrations compared to human foreskin fibroblasts (HFF). Antiviral and anti-cancer activity of chelating agents is caused by intracellular complexation of metal ions. DTPA, an extracellular chelator, was covalently coupled to human serum albumin (HSA) molecules, HSA nanoparticles (HSA-NP), gelatin type B (GelB) molecules, and GelB nanoparticles (GelB-NP) to increase cellular uptake. Coupling of DTPA to drug carrier systems increased its cytotoxic and antiviral activity by 5- to 8-fold. Confocal laser scanning microscope examination revealed uptake of DTPA-HSA-NP in UKF-NB-3 cells and HFF. Therefore, coupling of DTPA to protein-based drug carrier systems increases its antiviral and anti-cancer activity probably by mediating cellular uptake.     

Oxidation and methylation status determine the effects of arsenic on the mitotic apparatus

We investigated the spindle inhibitory properties of six arsenicals differing in their methylation or oxidation state. Human lymphoblasts were exposed for 6 h to either sodium arsenate (NaAs^V), sodium arsenite (NaAs^III), monomethylarsonic acid (MMA^V), monomethylarsonous acid (MMA^III), dimethylarsinic acid (DMA^V), or dimethylarsinous acid (DMA^III). After exposure slides were prepared, and the mitotic indices (MI) were assessed. We also exposed tubulin directly to each arsenical and spectrophotometrically measured its effect on polymerization. NaAs^V caused a small but significant increase in MI. MMA^V also caused only a slight increase in MI that just reached statistical significance. In contrast, DMA^V caused a significant increase in MI, producing ∼75% the MI of demecolcine and ∼4 times the MI of the control. NaAs^III had no significant effect on MI and was quite toxic. MMA^III induced more than a twofold increase in MI compared to the control, which was about 40% that caused by demecolcine. On a micromolar basis, MMA^III was the most potent of the arsenicals tested. DMA^III gave inconsistent results. None of the pentavalent arsenicals had a substantial effect (either inhibition or enhancement) on GTP-induced polymerization of tubulin. In contrast, NaAs^III inhibited polymerization at concentrations of 1 mM and above and MMA^III and DMA^III at 10 μM and above. Taken together, these results present a complex picture of how arsenicals may affect cells. These studies demonstrate that the metabolites of arsenic are active not only as chromosome breaking and DNA damaging agents but can also interfere with cell division via tubulin disruption.     

A biological tool with chemical applications

Chemistry researchers demonstrate the utility of the sandwich immunoassay for high-throughput screening of catalysts of organic coupling reactions.     

Untersuchungen über das Zusammenwirken von Gesichtssinn und Gehörsinn bei Elritzen (Phoxinus laevis Agass.)1

• 1 Zur Entscheidung der Frage, ob Elritzen akustische Reize zusätzlich zur optischen Orientierung als Information verwenden, wurden Versuchsfische auf gegensinnige wie auf gleichsinnige optische und akustische Signale abgerichtet.
• 2 Qualitative Versuche mit gegensinnigen Signalen ergaben Konfliktreaktionen, aus denen zu schließen ist, daß die Versuchstiere beide Reizmodalitäten gleichzeitig perzipieren. Die Fische reagierten hierbei auf Licht besser als auf Ton, gleichgültig ob dieser Futter- oder Warnsignal war.
• 3 Quantitative Versuche mit variierten Reizstärken zeigten, daß die Signale das Konfliktverhalten ihrer Stärke entsprechend beeinflussen, wobei der Dressursinn ohne Bedeutung ist.
• 4 Wenn Elritzen ein optisches Futtersignal nach längerem Darbieten infolge Gewöhnung nicht mehr beachteten, konnten sie durch einen Futterton wieder zum Futterlicht gelockt werden.
• 5 Die Untersuchungen zeigen, daß trotz vorwiegend optischer Orientierung dem Hörvermögen der Elritzen eine nicht unerhebliche Bedeutung zukommt.

     

Antenna organisation in the purple bacterium Rhodopseudomonas acidophila studied by fluorescence induction

The photosynthetic membrane of the purple bacterium Rhodopseudomonas (Rps.) acidophila is composed of reaction centers (RCs) which are surrounded by closely connected light harvesting complexes (LH1) and peripheral light-harvesting complexes (LH2). Both LH1 and LH2 – which bind the antenna pigments between -, -heterodimers – form rings composed of an integer number of -, -subunits. Here we use the sigmoidicity of fluorescence induction curves to probe the excitonic connectivity of RCs in order to gain information on the structural arrangement of these LH complexes in the natural chromatophore membrane. The data exclude models of the Rps. acidophila photosynthetic unit that assume aggregates of RC-LH1 complexes or linear chains of RC-LH1 complexes to which LH2 complexes are attached on the periphery. Rather, they support the model suggested by Papiz et al. ((1996) Trends in Plant Science 1: 198–206) in which peripheral light-harvesting rings tightly surround each core complex (LH1-ring with the RC inside) circumferentially.     

Isolation of Mycoplasma gallopavonis from free-ranging wild turkeys in coastal North Carolina seropositive and culture-negative for Mycoplasma gallisepticum.

Serum samples and choanal cleft swabs were collected from livetrapped and hunter killed wild turkeys (Meleagris gallopavo) from Martin and Bertie counties, North Carolina (USA). Sera were tested for antibodies to Mycoplasma gallisepticum, Mycoplasma synoviae and Mycoplasma meleagridis by hemagglutination inhibition (HI). Sera from 33% (five of 15) of livetrapped turkeys were positive for antibodies to M. gallisepticum by HI, and all were negative for antibodies to M. synoviae and M. meleagridis. Choanal cleft swabs from 22 livertrapped and five hunter killed wild turkeys cultured in Frey's broth medium resulted in 23 mycoplasma isolations. Using direct immunofluorescence, 74% (17/23) were M. gallopavonis, and 26% (six of 23) were unidentified; no isolate was identified as M. gallisepticum, M. synoviae or M. meleagridis.