Engineered CD4- and CXCR4-using simian immunodeficiency virus from African green monkeys is neutralization sensitive and replicates in nonstimulated lymphocytes

During human immunodeficiency virus type 1 (HIV-1) infection, disease progression correlates with the occurrence of variants using the coreceptor CXCR4 for cell entry. In contrast, apathogenic simian immunodeficiency virus (SIV) from African green monkeys (SIVagm), specifically the molecular virus clone SIVagm3mc, uses CCR5, Bob, and Bonzo as coreceptors throughout the course of infection. The influence of an altered coreceptor usage on SIVagm3mc replication was studied in vitro and in vivo. The putative coreceptor binding domain, the V3 region of the surface envelope (SU) glycoprotein, was replaced by the V3 loop of a CD4- and CXCR4-tropic HIV-1 strain. The resulting virus, termed SIVagm3-X4mc, exclusively used CD4 and CXCR4 for cell entry. Consequently, its in vitro replication was inhibited by SDF-1, the natural ligand of CXCR4. Surprisingly, SIVagm3-X4mc was able to replicate in vitro not only in interleukin-2- and phytohemagglutinin-stimulated but also in nonstimulated peripheral blood mononuclear cells (PBMCs) from nonhuman primates. After experimental infection of two pig-tailed macaques with either SIVagm3-X4mc or SIVagm3mc, the coreceptor usage was maintained during in vivo replication. Cell-associated and plasma viral loads, as well as viral DNA copy numbers, were found to be comparable between SIVagm3mc and SIVagm 3-X4mc infections, and no pathological changes were observed up to 14 months postinfection. Interestingly, the V3 loop exchange rendered SIVagm3-X4mc susceptible to neutralizing antibodies present in the sera of SIVagm3-X4mc- and SIVagm3mc-infected pig-tailed macaques. Our study describes for the first time a successful exchange of a V3 loop in nonpathogenic SIVagm resulting in CD4 and CXCR4 usage and modulation of virus replication in nonstimulated PBMCs as well as sensitivity toward neutralization.     

Underreplication of satellite DNAs in polyploid ovarian tissue of Drosophila virilis

The satellite DNAs of Drosophila virilis have been examined in diploid and polyploid tissues by isopycnic ultracentrifugation and thermal denaturation experiments. Previous work has established that the satellite DNAs are under replicated in the polytene chromosomes of the salivary glands of D. virilis. The results of the present experiments demonstrate that this underreplication also takes place in the ovaries which contain nurse cells and follicle cells. These tissues are polyploid but do not show polytene chromosomes.     

On the composition of the nucleolus with special reference to its filamentous structure

Summary Different staining procedures, various digestion methods and autoradiographic techniques were employed to study the structure and composition of the nucleolus and of the nucleolonema, after unmasking the latter by adenosine treatment. The presence of DNA, RNA, protein and lipid in these structures has been shown. It has been demonstrated that the filamentous structure within the nucleolus — the nucleolonema— has a core of DNA, around which RNA and protein have accumulated. The structure of the nucleolonema suggests that it is in a highly active state, in synthesizing ribosomal RNA and protein.We take the opportunity to express our gratefulness to the Director, Prof. Dr. Hans Lettré, for providing facilities to work in this Institute. We like to thank our other colleagues, particularly Dr. N. Paweletz, for their valuable help during the course of the investigations.     

?Anp?beln“ bei Jungmeisen (Parus): Entwicklung der Rangordnung

Zusammenfassung Ein bisher nur von Tannenmeisen (Parus ater) bekanntes agonistisches Ritual (seitliches Flügelflattern) wird auch für Blau-, Kohl- und Haubenmeisen (Parus caeruleus, Parus major undParus cristatus) nachgewiesen. Seitliches Flügelflattern besteht aus einer Sequenz von Verhaltenselementen, ist direkt gegen einen Artgenossen gerichter und führt in der überwiegenden Zahl der Fälle zu einer Verfolgungsjagd. Das Verhalten tritt in der frühen Jugendphase auf, in der innerhalb der Jungmeisengruppe noch keine Rangordnung besteht. Es wird am häufigsten um den Zeitpunkt des Selbständigwerdens gezeigt und ist im Alter von ca. 10 Wochen verschwunden. Das Verhalten spielt offensichtlich eine wichtige Rolle bei der Ausbildung der Rangordnung. Für das bis jetzt namenlose Verhalten wird der Ausdruck Anpöbeln vorgeschlagen.

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Molesting in juvenile tits (Parus spp.): On the formation of dominance order

Summary An agonistic ritual (one-sided wing flapping) which was only known in Coal Tits (Parus ater) could also be proved for Blue, Great and Crested Tits (Parus caeruleus, Parus major andParus cristatus). One-sided wing flapping is composed of a sequence of behavioural elements, it is focussed directly on a conspecific and results in a persuit chase in the vast majority of the cases. The behaviour is displayed during the early juvenile stage when there still does not exist a social order within the juvenile group members. This characteristic behaviour is most frequent until the eighth week and is no longer discerned from the tenth week on. Apparently this behaviour does play an important role during the formation of dominance order. It is proposed to call the unnamed behaviour molesting because of its special characteristics.

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Herrn Prof. F. Schaller zum 70. Geburtstag gewidmet.     

Beta‐diversity in temperate and tropical forests reflects dissimilar mechanisms of community assembly

Site‐to‐site variation in species composition (β‐diversity) generally increases from low‐ to high‐diversity regions. Although biogeographical differences in community assembly mechanisms may explain this pattern, random sampling effects can create this pattern through differences in regional species pools. Here, we compared assembly mechanisms between spatially extensive networks of temperate and tropical forest plots with highly divergent species pools (46 vs. 607 species). After controlling for sampling effects, β‐diversity of woody plants was similar and higher than expected by chance in both forests, reflecting strong intraspecific aggregation. However, different mechanisms appeared to explain aggregation in the two forests. In the temperate forest, aggregation reflected stronger environmental correlations, suggesting an important role for species‐sorting (e.g. environmental filtering) processes, whereas in the tropics, aggregation reflected stronger spatial correlations, more likely reflecting dispersal limitation. We suggest that biogeographical differences in the relative importance of different community assembly mechanisms contribute to these striking gradients in global biodiversity.     

Methicillin-Resistant Staphylococcus aureus in Saarland,Germany: The Long-Term Care Facility Study

BackgroundMultiresistant organisms pose a threat for patients and care recipients. Control interventions need to be tailored to region, the type of institution considered, and risk factors. The German state of Saarland is ideally suited to study colonisation epidemiology throughout its various health and care institutions. After conclusion of a large admission prevalence study in acute care hospitals, we now performed a methicillin-resistant Staphylococcus aureus (MRSA) point prevalence study in Saarland long term care facilities (LTCF), allowing for a direct comparison with respect of MRSA prevalence and associated risk factors between these two institutional types located within a confined region.ConclusionAs already known from previous studies, colonisation with MRSA is common in LTCF residents even in an area with relatively low MRSA prevalence. This found prevalence can now be related to the acute care admission prevalence (2.2%) as well as to the admission prevalence in acute care geriatric departments (7.6%). The common clonal attribution (spa type) of MRSA isolates prevalent in the LTCF population as well as in the acute care admission population points towards a close relationship between both types of institutions. However, the ostensible absence of risk factors such as “previous hospitalisation” in conjunction with newly identified factors such as “multiple decolonisation cycles” refers to MRSA colonisation risks independent of contact with acute care facilities. Overall, this large LTCF point prevalence study allows data-based, region-tailored decisions on MRSA screening policies and provides a basis for additional preventative measures.     

Biotransformation of biphenyl by the filamentous fungus <Emphasis Type="Italic">Talaromyces helicus</Emphasis>

The filamentous fungusTalaromyces helicus , isolated from oil-contaminated sludge, oxidizes biphenyl via 4-hydroxybiphenyl to the dihydroxylated derivatives 4,4-dihydroxybiphenyl and 3,4-dihydroxybiphenyl, which, to a certain extent, are converted to glycosyl conjugates. The sugar moiety of the conjugate formed from 4,4-dihydroxybiphenyl was identified as glucose. Further metabolites: 2-hydroxybiphenyl, 2,5-dihydroxylated biphenyl, and the ring cleavage product 4-phenyl-2-pyrone-6-carboxylic acid accumulated only in traces. From these results the main pathway for biotransformation of biphenyl in T. helicus could be proposed to be the excretion of dihydroxylated derivatives (>75%) and their glucosyl conjugates (<25%).     

High affinity insulin binding and insulin receptor-effector coupling: modulation by Ca2+.

Insulin binding and insulin stimulated amino acid and glucose uptake were determined in cultured HTC hepatoma cells in the presence of Ca2+ and ruthenium red (RR) in order to further characterise the putative calcium binding site on the receptor. These ions increased insulin receptor high affinity binding and the sensitivity of these responses to insulin. The insulin concentration required to half-maximally stimulate amino acid uptake decreased significantly from 26.9 +/- 5.8 ng/ml to 6.0 +/- 1.3 ng/ml in the presence of 10 mM Ca2+ and to 1.3 +/- 0.5 ng/ml in the presence of RR. The effect of Ca2+ and RR was more pronounced on insulin stimulated glucose uptake. These agents also increased receptor-effector coupling, reducing the percentage of occupied receptors required for maximal insulin stimulation of amino acid uptake from 10.8% in control cells to 3.4 and 1.4% in the presence of Ca2+ and RR respectively. The receptor occupancy required to produce maximal insulin responses on glucose uptake decreased from 20% (control) to 3.8% (Ca2+ and RR). We hypothesize that since Ca2+ and RR have similar effects, that occupation of Ca2+ binding sites on the receptor produces a conformational change in the insulin receptor which increases insulin receptor affinity, insulin sensitivity and acts on an early post-receptor event responsible for coupling binding to insulin action.