Chloroplast DNA restriction analysis and the infrageneric grouping ofAllium (Alliaceae)

The utility of chloroplast DNA variation for checking a recently proposed infrageneric classification of the genusAllium was tested. cpDNA restriction patterns of 49 species representing the main subgenera, sections, and subsections of the existing classification were compared. 363 different fragments generated by 4 restriction enzymes were identified and analysed by UPGMA clustering. The resulting phenogram largely confirms the subgeneric classification based on an integration of morphological and other methods.     

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.     

Molekularbiologie der Mukoviszidose

Mukoviszidose ist eine angeborene Funktionsstörung der exokrinen Körperdrüsen. Sie kommt bei etwa 1 : 2500 Lebendgeborenen in der weißen Bevölkerung Europas und Nordamerikas vor und gehört damit zu den häufigsten lebensbedrohlichen Erbkrankheiten des Menschen. Dennoch sind vollständige Beschreibungen des Krankheitsbildes erst seit etwas mehr als fünfzig Jahren bekannt. Die bei den meisten Mukoviszidosekranken auftretenden fibrotischen Veränderungen (Fibrose - Vermehrung des Bindegewebes) der Bauchspeicheldrüse haben zu der Bezeichnung cystic fibrosis of the pancreas geführt, so daß auch der Name zystische Fibrose (cystic fibrosis, CI) heute synonym gebräuchlich ist. Wir wollen im folgenden in kurzer Form auf die Symptome und Ursachen der Erkrankung eingehen. Eine ausführlichere Darstellung der Mukoviszidose und ihrer molekularbiologischen Grundlagen mit zahlreichen Literaturhinweisen ist kürzlich aktualisiert und erweitert worden [21].     

Algorithm independent properties of RNA secondary structure predictions

Algorithms predicting RNA secondary structures based on different folding criteria – minimum free energies (mfe), kinetic folding (kin), maximum matching (mm) – and different parameter sets are studied systematically. Two base pairing alphabets were used: the binary GC and the natural four-letter AUGC alphabet. Computed structures and free energies depend strongly on both the algorithm and the parameter set. Statistical properties, such as mean number of base pairs, mean numbers of stacks, mean loop sizes, etc., are much less sensitive to the choice of parameter set and even of algorithm. Some features of RNA secondary structures, such as structure correlation functions, shape space covering and neutral networks, seem to depend only on the base pairing logic (GC or AUGC alphabet). Received: 16 May 1996 / Accepted: 10 July 1996     

Studies on the uptake and intracellular replication of Legionella pneumophila in protozoa and in macrophage-like cells

Abstract Legionella pneumophila strains isolated from different sources were tested for their host range in the protists Acanthamoeba castellanii, Hartmannella vermiformis and Entamoeba histolytica . It has been shown that A. castellanii and H. vermiformis but not E. histolytica support the intracellular replication of L. pneumophila . Furthermore it could be demonstrated that in vivo virulence in the guinea pig and the intracellular growth in U937 cells coincides with the capability to replicate intracellularly in A. castellanii at 37°C. The infectivity of L. pneumophila that had sustained a 48 hours nutrient deprivation was not significantly different from that of legionellae grown to log-phase on BCYE plates. In contrast the nutrient limitation on A. castellanii increased the amount of intracellular legionellae at the beginning of infection. An initial opsonin independent attachement stage of legionellae to U937 cells was demonstrated by scanning electron microscopy. In contrast, L. pneumophila's capability of stable or long term attachmennt to A. castellanii was shown to be inefficient.     

Statistics of RNA melting kinetics

We present and study the behavior of a simple kinetic model for the melting of RNA secondary structures, given that those structures are known. The model is then used as a map that. assigns structure dependent overall rate constants of melting (or refolding) to a sequence. This induces a landscape of reaction rates, or activation energies, over the space of sequences with fixed length. We study the distribution and the correlation structure of these activation energies. Correspondence to: P. Schuster     

Octopamine-like immunoreactive neurones in locust genital abdominal ganglia

Using a well characterized anti-serum, the distribution of octopamine-like immunoreactive neurones is described in the locust seventh abdominal (A7) and terminal ganglia (TG), which are associated with genital organs. Apart from 4 paired ventral somata occasionally observed in the TG, all labelled cells could be identified as efferent dorsal- and ventral unpaired median (DUM/VUM) neurones by virtue of the characteristic large size and position of their somata, projections of their primary neurites in DUM-cell tracts, and bifurcating axons which arise from dorsal T-junctions and enter peripheral nerves. For the examined ganglia our data indicate that the whole population of efferent DUM and VUM-cells, defined here as progeny of the segment specific unpaired median neuroblast with peripheral axons, are octopaminergic, and that equal numbers of these cells occur in both sexes: 8 in A7 and 11 in TG. Sex-specific differences are probably restricted to the axonal projections of 5 octopamine-like immunoreactive DUM-somata in A7, and 5 in TG, which in females project into their segment specific sternal nerves, but in males into the genital nerve of the TG. Numerous intersegmentally projecting octopamine-like immunoreactive fibres traverse both ganglia. The majority probably stem from previously described octopamine-like immunoreactive neurones in the thoracic and suboesophageal ganglia.