A source of hidden diversity: soil seed bank and aboveground populations of a common herb contain similar levels of genetic variation.

In many landscapes, successful re-establisment of plant populations depends on the presence of diaspores, either near or directly beneath sites to be restored. The soil seed bank is, therefore, an important part of ecosystem resilience and a vital pillar for regeneration of genetic diversity in many plant populations. However, regeneration from the soil seed bank and the siubsequent restoration can only be considered successful when genetic diversity of restored populations is not eroded nor genetic differentiation inflated. We compared genetic variation within and among soil seed bank and aboveground populations of Origanum vulgare, to test whether genetically variable populations can be restored from the soil seed bank. We explored levels of genetic diversity within aboveground populations and the corresponding soil seed banks. Furthermore, we assessed the extent to which the soil seed bank differs genetically from the aboveground population. Levels of genetic diversity were to generally similar in aboveground populations and the corresponding soil seed banks. Only levels of inbreeding were slightly higher in the lower layer of the soil seed bank compared to the aboveground populations, probably because of selection processes acting against homozygotes accumulating in the seed bank. Furthermore, significant genetic differentiation between the aboveground population and the corresponding seed banks was completely absent. Across all sites, genetic differentiation between the soil seed bank was similar to that between aboveground populations, probably due to the absence of severe climate conditions, strong bottlenecks or disturbance events. Our conclusions support the possibility of successful re-establishment of healthy, genetically variable plant populations after aboveground destruction or following soil re-allocation from persistent seed banks.

Impact of river dynamics on the genetic variation of Gypsophila repens (Caryophyllaceae): a comparison of heath forest and more dynamic gravel bank populations along an alpine river.

Alpine rivers are, despite anthropogenic water flow regulation, still often highly dynamic ecosystems. Plant species occurring along these rivers are subject to ecological disturbance, mainly caused by seasonal flooding. Gypsophila repens typically grows at higher altitudes in the Alps, but also occurs at lower altitudes on gravel banks directly along the river and in heath forests at larger distances from the river. Populations on gravel banks are considered non-permanent and it is assumed that new individuals originate from seed periodically washed down from higher altitudes. Populations in heath forests are, in contrast, permanent and not regularly provided with seeds from higher altitudes through flooding. If the genetic structure of this plant species is strongly affected by gene flow via seed dispersal, then higher levels of genetic diversity in populations but less differentiation among populations on gravel banks than in heath forests can be expected. In this study, we analysed genetic diversity within and differentiation among 15 populations of G. repens from gravel banks and heath forests along the alpine River Isar using amplified fragment length polymorphisms (AFLP). Genetic diversity was, as assumed, slightly higher in gravel bank than in heath forest populations, but genetic differentiation was, in contrast to our expectations, comparable among populations in both habitat types. Our study provides evidence for increased genetic diversity under conditions of higher ecological disturbance and increased seed dispersal on gravel banks. Similar levels of genetic differentiation among populations in both habitat types can be attributed to the species' long lifetime, a permanent soil seed bank and gene flow by pollinators among different habitats/locations.

Molecular markers provide evidence for a broad-fronted recolonisation of the widespread calcareous grassland species Sanguisorba minor from southern and cryptic northern refugia.

Calcareous grasslands belong to the most species-rich and endangered habitats in Europe. However, little is known about the origin of the species typically occurring in these grasslands. In this study we analysed the glacial and post-glacial history of Sanguisorba minor, a typical plant species frequently occurring in calcareous grasslands. The study comprised 38 populations throughout the whole distribution range of the species across Europe. We used molecular markers (AFLP) and applied Bayesian cluster analysis as well as spatial principal components analysis (sPCA) to identify glacial refugia and post-glacial migration routes to Central Europe. Our study revealed significant differences in the level of genetic variation and the occurrence of rare fragments within populations of S. minor and a distinct separation of eastern and western lineages. The analyses uncovered traditional southern but also cryptic northern refugia and point towards a broad fronted post-glacial recolonisation. Based on these results we postulate that incomplete lineage sorting may have contributed to the detected pattern of genetic variation and that S. minor recolonised Central Europe post-glacially from Iberia and northern glacial refugia in France, Belgium or Germany. Our results highlight the importance of refugial areas for the conservation of intraspecific variation in calcareous grassland species.

Genetic variation of Mimetes hirtus and Mimetes fimbriifolius (Proteaceae) - a comparative analysis of two closely related fynbos species.

We investigated the influence of differing life history traits on the genetic structure of the related species Mimetes fimbriifolius and Mimetes hirtus (Proteaceae), which occur in the South African fynbos. Both species are bird-pollinated and ant-dispersed, but differ in rarity, longevity, ecological strategy and the fragmentation of their distribution area. We used AFLPs to study genetic variation within and between 21 populations of these two species across their distribution range. AFLP analysis revealed significantly higher genetic variation within populations of M. fimbriifolius than within M. hirtus. While M. fimbriifolius clearly lacked any significant genetic differentiation between populations, a distinct geographic pattern was observed for M. hirtus. Differentiation was, however, stronger at the regional (Phi(PT) = 0.57) than at the local scale (Phi(PT) = 0.08). Our results clearly indicate that even closely related species that share the same mode of pollination and seed dispersal can differ in their genetic structure, depending on the magnitude of fragmentation, longevity of individuals and ecological strategy.

Genetic differentiation among populations of Sesleria albicans Kit. ex Schultes (Poaceae) from ecologically different habitats in central Europe.

As observed for many other plant species, the populations of Sesleria albicans in Central Europe are located in habitats, which differ to a high degree from each other with regard to ecological factors such as nutrients, light and water as well as in type of land use. The species colonizes limestone cliffs, pavements, screes, grazed and mown grasslands, heaths, fens and open woodlands. In this study, we used random amplified polymorphic DNA (RAPD) analysis to investigate the genetic differentiation among 25 populations of S. albicans from six different types of habitat (beech forests, alpine and lowland rocky ridges, lowland screes, fens, calcareous grasslands). With RAPD analysis, 344 fragments could be amplified, of which 95.9% were polymorphic. The level of polymorphism ranged from 29.7 to 56.7% polymorphic bands per population and was correlated with population size. In an analysis of molecular variance (AMOVA), used to detect variation among individuals within populations, among populations from the same habitat and among different habitats, most of the genetic variation was found within populations (62.06%) and among populations from the same habitat (33.36%). In contrast, only a very low level of differentiation could be observed among different habitats (4.58%). The results of our study give only little evidence for an ecotypic differentiation of Sesleria albicans. This differentiation is principally conceivable, but obviously not related to the investigated RAPD loci.

Clearance of recombinant tissue factor pathway inhibitor (TFPI) in rabbits.

The pharmacokinetics of recombinant tissue factor pathway inhibitor (TFPI) after an intravenous bolus injection was studied in rabbits. Clearance of TFPI was followed by measurement of the radioactivity of the 125I-labelled compound in the whole plasma or the trichloroacetic acid precipitate and by quantitation of the functional TFPI activity of the unlabelled compound using a tissue factor-induced coagulation assay. When iodinated TFPI was used, the ratios of the trichloroacetic acid precipitable counts vs. that of the whole plasma was about 1 in the first 10 min after TFPI injection, but this ratio gradually decreased to less than 0.5 after 2 h. This result suggested that the iodinated TFPI in the plasma was partially degraded after prolonged circulation in the animal. When unlabelled TFPI was used, the clearance of TFPI activity from the plasma exhibited bi-exponential elimination kinetics with a rapid alpha phase half-life (t1/2 alpha) of 2.3 min, and a terminal beta phase half-life (t1/2 beta) of 79 min. The plasma clearance was 4.2 ml kg-1 min-1. The tissue distribution of intravenously administered 125I-TFPI in the rabbit was studied using whole-body autoradiography. At 3 min after dosing, significant levels of TFPI were apparent in the liver, kidney, and other highly blood perfused tissues. Significant levels of 125I-TFPI-derived radioactivity were also apparent in the liver and kidney at 30 min after intravenous administration. The localization within the liver demonstrated a mottled appearance, suggesting regions of higher uptake within the liver. In the kidney, the outer cortex consistently revealed the highest activity.

[Renal effects of conversion enzyme inhibitors]. / Renale Effekte der Konversionsenzymhemmer.

Recently it has been recognized that even minor elevations of blood pressure contribute to progression of renal failure. Furthermore it has been documented that antihypertensive treatment retards progression of renal failure. Despite impressive experimental data firm clinical evidence, incontrovertible on biostatistical grounds, is not yet available to document that converting enzyme inhibitors (CEI) are superior to alternative antihypertensive agents with respect to halting progression. CEI undoubtedly reduce albuminuria, independent of their effect on systemic blood pressure, and this is related to alterations of glomerular permeability. Recent experimental data suggest that growth processes in damaged kidneys are an important aspect of progression. It is a fascinating perspective, but yet unproven, that CEI interfere with these processes.

Use of angiotensin-converting enzyme inhibitors for the preservation of kidney function. A retrospective study.

To investigate the effects of angiotensin-converting enzyme (ACE) inhibitors on renal outcome in patients with renal insufficiency, a 2-part study was conducted. Part A consisted of a retrospective 1-year analysis of 80 hypertensive outpatients with serum creatinine levels of 1.5-6 mg/dl, 39 of whom received ACE inhibitors and other antihypertensive agents and 41 of whom received only other antihypertensive agents. Median serum creatinine levels in the ACE group rose acutely from 2.33 to 2.7 mg/dl after 1 month of therapy and remained stable thereafter. Serum creatinine levels more than doubled in 2 patients. In controls, median serum creatinine levels rose gradually over 12 months from 2.39 to 3.45 mg/dl, and serum creatinine more than doubled in 9 patients. Part B consisted of a prospective follow-up of patients for a second year; 34 patients in the treatment group and 32 controls were then analyzed; median serum creatinine level was 3.0 vs. 4.4 mg/dl after 2 years; 2 of 34 vs. 6 of 32 patients were on dialysis; serum creatinine level had more than doubled in 4 of 34 vs. 8 of 32. These results suggest that ACE inhibitors are more effective than other antihypertensive agents in reducing the progression of renal failure.

Effects of WY 47987 (atrial natriuretic factor 102-126) in patients with renal insufficiency: a placebo-controlled, randomised study.

We studied renal, hormonal and cardiovascular effects of ANF 102-126 (WY 47987) in seven patients with chronic renal failure (serum creatinine 25-68 mg/l) and in four normal volunteers. ANF or placebo bolus injections were given at 1, 2, and 3 micrograms/kg i.v. (each dose on separate days). As compared to placebo, ANF did not induce changes of renal excretory parameters, of plasma renin and aldosterone or of blood pressure and heart rate in patients. In healthy volunteers, however, the same dose of ANF increased urinary excretion of sodium, potassium, calcium, chloride and phosphorus as well as water, and creatinine clearances, and decreased plasma aldosterone. The data suggest blunted effectiveness of ANF bolus injections in patients with renal insufficiency.

[Conversion enzyme inhibitors in the antihypertensive treatment of patients with renal insufficiency]. / Konversionsenzymhemmer in der antihypertensiven behandlung niereninsuffizienter Patienten.

Changes in serum creatinine concentration and proteinuria over a period of 12 months were analysed retrospectively in hypertensives in renal failure, 39 treated with conversion-enzyme inhibitors and 41 treated with other antihypertensives. The occasionally recorded blood pressures were comparable in the two groups. Median serum creatinine levels in the patients treated with conversion-enzyme inhibitors rose from 2.33 mg/100 ml (range 1.5-5.5) after one month acutely by 0.4 mg/100 ml and then remained essentially constant. In nine patients the level was higher by greater than or equal to 0.5 mg/100 ml after 12 months than at the beginning of treatment. Proteinuria did not show any identifiable changes. On the other hand, in those patients treated with other antihypertensives, median serum creatinine concentration rose gradually over 12 months from 2.4 mg/100 ml (range 1.5-6.0) to 3.45 mg/100 ml (1.5-12.9). In 18 patients the serum creatinine level rose by less than or equal to 0.5 mg/100 ml. Five patients developed side effects to conversion-enzyme inhibitors, but none required discontinuation of treatment. It is concluded that the use of conversion-enzyme inhibitors in patients with renal failure is effective and largely safe. It apparently causes less of a rise in serum creatinine than other antihypertensives.