Different influences of cytochalasin B on the activation of human neurophils settled onto petri dishes displayed by simultaneously detected native and luminol-dependent luminescence

Cytochalasin B (CB) is known to interfere reversibly with the cytoplasmic contractile filamental network of mammalian cells. The role of the microfilament system in the mechanism of the reactive oxygen intermediates release of polymorphonuclear leukocytes (PMNL) was studied for different kinds of stimuli. PMNL from fresh human blood were treated with CB and stimulated by adherence on plastic surfaces, by opsonized zymosan, by phorbol myristate acetate and by N-formylmethionyl-phenylalaline. The production of reactive oxygen species were monitored by simultaneous detection of native, luminol-independent, luminescence (NL) and luminol-dependent luminescence (LDL) using a method of spectral discrimination. Different influences of CB on NL with respect to LDL as well stimuli-dependent influences of CB on the luminescence response of PMNL were observed. Especially phagocytosis-associated activation of PMNL was strongly inhibited by CB, whereas LDL was reduced to a much greater extent in comparison with NL. A firm involvement of the microfilament system is indicated, but it depends on the kind of stimulus engaged.     

Langzeit-Erfassung brutbiologischer Parameter beim KleiberSitta europaea in zwei norddeutschen Untersuchungsr?umen

Zusammenfassung Der Zusammenstellung liegen Befunde zu den brutbiologischen Parametern Gelegestärke, Schlüpftermin und Anzahl flügger Junge zugrunde, die von 1970–1995 an rund 1500 Erstbruten des Kleibers in Versuchsgebieten mit künstlichen Nisthöhlen bei Braunschweig und Essen gewonnen wurden. Die Vollgelege-Eizahl beträgt im Durchschnitt 6,8 Eier (nur Daten aus dem Braunschweiger Raum), der durchschnittliche Schlüpftermin fällt auf den 9. Mai (Braunschweig) und 6. Mai (Essen) und die Anzahl flügger Nestlinge liegt in erfolgreichen Bruten im Mittel bei 5,6 (Braunschweig) bzw. 5,2 (Essen). Im Untersuchungszeitraum kam es in beiden Gebietsregionen zu einer signifikanten Verfrühung des Bruttermins. Doch werden wohl erst die Befunde der kommenden Jahre zeigen können, ob die rezente Häufung früher Brutjahre beim Kleiber (diese Arbeit) und bei Kohl- und Blaumeisen (Winkel &Hudde unveröff.) bereits eine Folge des anthropogen bedingten global warming ist oder noch das normale Auf und Ab der Witterung widerspiegelt.

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Long-term changes of breeding parameters of NuthatchesSitta europaea in two study areas of northern Germany

Between 1970 and 1995, nestbox data about clutch size, hatching date and fledging success were collected for a total of around 1500 first broods of Nuthatches in two north German study areas (near Brunswick 52.16 N 10.32 E and near Essen 51.24 N 6.59 E). The average clutch size was 6.8 eggs (Brunswick), the average hatching date 9 May (Brunswick) and 6 May (Essen), and the mean number of fledglings per successful brood 5.6 (Brunswick) and 5.2 (Essen). Over time hatching dates significantly advanced in both areas. Data of further years are needed to clarify if the recent unusual sequence of early breeding years in the Nuthatch is already a consequence of the anthropogenic greenhouse effect or just due to normal variation of weather conditions.

     

Mechanism of MAT alpha donor preference during mating-type switching of Saccharomyces cerevisiae.

During homothallic switching of the mating-type (MAT) gene in Saccharomyces cerevisiae, a- or alpha-specific sequences are replaced by opposite mating-type sequences copied from one of two silent donor loci, HML alpha or HMRa. The two donors lie at opposite ends of chromosome III, approximately 190 and 90 kb, respectively, from MAT. MAT alpha cells preferentially recombine with HMR, while MATa cells select HML. The mechanisms of donor selection are different for the two mating types. MATa cells, deleted for the preferred HML gene, efficiently use HMR as a donor. However, in MAT alpha cells, HML is not an efficient donor when HMR is deleted; consequently, approximately one-third of HO HML alpha MAT alpha hmr delta cells die because they fail to repair the HO endonuclease-induced double-strand break at MAT. MAT alpha donor preference depends not on the sequence differences between HML and HMR or their surrounding regions but on their chromosomal locations. Cloned HMR donors placed at three other locations to the left of MAT, on either side of the centromere, all fail to act as efficient donors. When the donor is placed 37 kb to the left of MAT, its proximity overcomes normal donor preference, but this position is again inefficiently used when additional DNA is inserted in between the donor and MAT to increase the distance to 62 kb. Donors placed to the right of MAT are efficiently recruited, and in fact a donor situated 16 kb proximal to HMR is used in preference to HMR. The cis-acting chromosomal determinants of MAT alpha preference are not influenced by the chromosomal orientation of MAT or by sequences as far as 6 kb from HMR. These data argue that there is an alpha-specific mechanism to inhibit the use of donors to the left of MAT alpha, causing the cell to recombine most often with donors to the right of MAT alpha.     

Localization of α1-adrenoceptors in rat and human hearts by immunocytochemistry

The localization of the ai adrenoceptors (₁-AR) in the heart tissues from rat and human and in the cultured heart cells from neonatal rats was studied by indirect immunofluorescence and postembedding electronmicroscopical immuno-gold technique. With antipeptide antibodies directed against the second extracellular loop of the human ₁-AR (AS sequence 192–218), this receptor was found to be localized along the sarcolemma in both human and rat hearts. Similar localization sites were detected in cultivated rat neonatal cardiomyocytes. Beside the localization in cardiomyocytes, ₁-AR were identified in endothelial cells of capillaries and smooth muscle cells of coronary vessels, in neuronal endings, in mast cells of cultivated heart cells but not, or in less amount in fibroblasts. Interestingly, in the right atrium of rat heart the localization of ₁-AR was found to be near or on atrial natriuretic factor (ANF) granules, providing the basis for the -adrenergic influence on ANF release. The immunocytochemical studies further confirm and complete the findings known by using autoradiographic binding studies with specific ligands.     

Reduction of cardiac hypertrophy in TGR(mREN2)27 by angiotensin II receptor blockade

TGR(mREN2)27 is a transgenic rat harboring the murine Ren-2 gene and exhibit fulminant hypertension and marked heart hypertrophy. In order to study the role of angiotensin II in the increase of cardiac mass, these animals were treated with anti-hypertensive and non-antihypertensive doses of the angiotensin II receptor AT₁ antagonist Telmisartan for 9 weeks. All doses led to significant reductions of heart hypertrophy detected by the evaluation of the diameter of cardiac muscle bundles. We conclude from this study that cardiac hypertrophy in TGR(mREN2)27 is characterized by an increased volume of cardiomyocytes and an unchanged amount of fibrous tissue and that angiotensin II plays an important role in the mechanisms leading to this phenotype.     

Agglutinierte Foraminiferen aus Graptolithen-Schwarzschiefern des Llanvirnium (Ordovizium) von Plettenberg im Sauerland (Nordrhein-Westfalen,NW-Deutschland)

The Plettenberger Bänderschiefer (Ordovician, Lower Llanvirnian, Zone ofDidymograptus bifidus (Hcall) from the type locality at Plettenberg (Sauerland, NW-Germany) yielded a foraminiferal fauna consisting of primitive agglutinated species (Amphitremoida, Bathysiphon,?Raibosammina, ?Thekammina, Thurammina). Forming one of the stratigraphically oldest European foraminiferal assemblages, these taxa were washed out of an unconsolidated graptolite siltstone and represent a pelagic, oxygen-depleted environment.