Local and systemic renin–angiotensin system participates in cardiopulmonary–renal interactions in monocrotaline-induced pulmonary hypertension in the rat

Renin–angiotensin system (RAS) is one of the pathophysiological mechanisms in heart failure. Recently, involvement of the kidney in the disease progression has been proposed in patients with pulmonary arterial hypertension (PAH). We hypothesized that local and systemic RAS could be the central regulators of cardiopulmonary–renal interactions in experimental monocrotaline-induced pulmonary hypertension (PH) in rats. Male 12-week-old Wistar rats were injected subcutaneously with monocrotaline (60 mg/kg). The experiment was terminated 4 weeks after monocrotaline administration. Using RT-PCR, we measured the expression of RAS-related genes in right and left ventricles, lungs and kidneys, together with indicators of renal dysfunction and damage. We observed a significantly elevated expression of angiotensin-converting enzyme (ACE) in both left and right ventricles and kidneys (P < 0.05), but a significantly decreased ACE in the lungs (P < 0.05). Kidneys showed a significant 2.5-fold increase in renin mRNA (P < 0.05) along with erythropoietin, TGFβ₁, COX-2, NOS-1 and nephrin. Expression of erythropoietin correlated inversely with hemoglobin oxygen saturation and positively with renin expression. In conclusion, monocrotaline-induced PH exhibited similar alterations of ACE expression in the left and right ventricles, and in the kidney, in contrast to the lungs. Increased renal renin was likely a consequence of renal hypoxia/hypoperfusion, as was increased renal erythropoietin expression. Alterations in RAS in the monocrotaline model are probably a result of hypoxic state, and while they could serve as a compensatory mechanism at a late stage of the disease, they could be viewed also as an indicator of multiorgan failure in PAH.

     

Changes in endogenous gibberellins in plant organs producing and utilizing photosynthates

The distribution of endogenous gibberellin-like substances in individual organs ofZea mays L., cv. CE 250, plants was investigated during the transition from the vegetative to the generative phase of development. The gradient of the content of gibberellin-like substances and photosynthetic activity in leaf segments was followed in different parts of the Jeaves, as well as the changes in the content of gibberellin-like substances in leaf segments during an exposure in the light and in the dark. The gradient of the content of endogenous gibberellin-liko substances in the leaves, in the stem and in the spike is interpreted in terms of possible relationship of these compounds to the regulation of sink — source.     

Does pollen limitation affect population growth of the endangered Dracocephalum austriacum L.?

Reproductive strategies can have significant consequences for the viability of plant populations. Still, the effects of lower fruit set due to pollen limitation on plant demography and population persistence have rarely been explored. The objectives of this study were to assess the ecological factors determining female reproductive success and to study the impact of pollen limitation on population growth of Dracocephalum austriacum L. (Lamiaceae), a critically endangered species with a discontinuous distribution across Europe. Despite the significant background information gathered on the population dynamics and genetic diversity of D. austriacum, little is known about its reproductive strategy and the effect it has on population growth. Thus, the reproductive system, pollinator assemblage and pollen limitation were studied in natural populations and the impact of pollen-limited seed production on population growth was assessed using existing transition matrix models. The results revealed that D. austriacum is protandrous self-compatible species that produces very few seeds in the absence of pollinators. The flowers are visited by several insects, including legitimate pollinators (e.g., Bombus hortorum, Osmia spp.) and nectar robbers (other Bombus spp., O. aurulenta). Fruit and seed production was significantly pollen-limited in all populations studied. However, despite the positive effect of pollen supplementation on seed production, the resulting increase in seed number did not significantly increase population growth rates in any of the studied populations. Hence, we conclude that populations are demographically stable and current natural seed production is sufficient for the species’ persistence.     

Mitochondrial chloride channels - What are they for?

This minireview focuses on observation of the properties, functional significance, and modulation of single chloride channels in the mitochondrial inner membrane using two electrophysiological methods - the patch-clamp and bilayer lipid membrane methods. Measurements of parameters such as conductance, Cl⁻/K⁺ selectivity, voltage or pH dependence as well as their modulation by endogenous and exogenous compounds using individual mitochondrial chloride channels result in an unexpectedly wide range of values. This paper discusses the origin of this wide variety of channel parameters and the possible involvement of these channels in mitochondrial membrane potential oscillations, apoptosis, carrier function, and mitochondrial fusion and fission.     

Enzymic Preparation of Benzyl β-D-Glucopyranoside

Benzyl β-D-glucopyranoside was prepared by an enzyme-catalysed direct reaction between D-glucose, or better cellobiose, and benzyl alcohol in the presence of a minimum amount of water. The enzyme β-glucosidase was used in the immobilized form (adsorbed onto macroporous polyethylene terephthalate or covalently bound on polyglycidyl methacrylate), enabling multiple application.     

Numerical syntaxonomy of the tall-forb and tall-grass communities in the Tatra Mountains

The tall-forb and tall-grass subalpine and alpine vegetation belonging to the Mulgedio-Aconitetea from the Tatra Mountains was subjected to reclassification with Complete Linkage Clustering. The communities are classified into 3 alliances: Adenostylion, Calamagrostion villosae and Trisetion fusci. It was concluded that the orders Adenostyletalia and Calamagrostietalia villosae should be fused into one unit. Synecological relations of the communities was clarified using a series of Detrended Correspondence Analyses.Abbreviations CLC = Complete Linkage Clustering - DCA = Detrended Correspondence Analysis     

High-altitude vegetation of the Western Carpathians — a syntaxonomical review

This paper presents a survey of high-altitude plant communities which occur in the Western Carpathians with an enumeration of the characteristic, transgressive and differential species of the individual alliances, orders and classes. It describes the tall-herb vegetation (Mulgedio-Aconitetea) and communities of the subalpine shrubs (Betulo carpaticae-Alnetea viridis), the montane and alpine calcareous swards (Elyno-Seslerietea), the wind-exposed cryophilous swards on ridge edges with low snow cover (Carici rupestris-Kobresietea bellardii), the chionophilous communities of snow beds and snow fields (Salicetea herbaceae), the arctic-boreal dwarf-shrub heathlands (Loiseleurio-Vaccinietea), the alpine acidophilous grasslands (Caricetea curvulae) and the high-mountain mat-grass swards of the alliance Nardion strictae (Nardetea strictae).     

Genetic diversity affects productivity in early but not late stages of stand development

Recent declines in the genetic diversity of populations have stimulated research on the importance of genetic diversity for the functioning of natural communities. Current studies on this topic are based on the exploration of a limited number of clones and do not allow distinctions to be made between the effects of genetic identity and genetic diversity per se and to evaluate the effects of genetic diversity in genetically diverse communities. Also, most information comes from short-term studies, which are insufficient for evaluating the long-term effects relevant in relatively undisturbed communities of perennial species.We explored the importance of clone diversity vs. clone identity for stand productivity and the changes of the pattern over time. We used 18 clones of a perennial grass, Festuca rubra, to establish a set of communities composed of 1, 6 or 18 clones in two environments and studied the effects of genetic diversity on stand productivity over 3 years.Genetic diversity had a significant effect on stand productivity in the 1st year but not in the 2nd or 3rd year. In most cases, the observed yield was not significantly different from the total expected yield. The biomass of the mixtures never outperformed the biomass of the most productive clone, suggesting that clone identity is an important determinant of total biomass.The results indicate that the effects of genetic diversity on stand productivity may be transient and suggest that the conclusions of short-term studies on diversity effects should be evaluated carefully. They also suggest that individual clones are not complementary and that the properties of the stands are mainly additive results of the properties of the constituent clones.     

Automated egg-collecting and pupa-separator system for medfly mass-rearing facilities

The new automated egg-collecting system and pupa-separator device described here substantially reduces labour during medfly [ Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)] mass production. The egg-collecting system gathers eggs dropping from the cage's oviposition net into a continuous stream of water, after which they accumulate in an egg-collecting sieve. The system provides an optimal environment for eggs, keeping them in a slow stream of well-oxygenated water. A pupa separator was designed to enable the separation of pupae from the pupation medium by sucking off the medium through a slowly moving sieving belt. The smaller particles of pupation medium are removed by a vacuum cleaner located under the circular sieving belt, and the pupae are collected in a collecting box. Quality control tests of the eggs collected and pupae separated have shown that neither system has a negative effect on the quality of the eggs or the pupae.