Cortisol and cortisone production in rat and mouse adrenal incubations

The presence of 17 alpha-hydroxylase in rodent adrenals is debated. The presence in blood of mice of 11-deoxycortisol together with the absence of cortisol is well known. We demonstrated here the in vitro synthesis of 17 alpha-hydroxyprogesterone and cortisol from [3H]progesterone in rat and mouse adrenals. We have shown that these syntheses represented 45 and 28% of those of 11-deoxycorticosterone and corticosterone, respectively, from progesterone. These data clearly suggest the presence of a 17 alpha-hydroxylase activity in vitro in these rodents adrenals. In addition, a noticeable synthesis of cortisol (0.87-1.57% per mg tissue, i.e. 52-64% per incubation flask) from 11-deoxycortisol was also observed and was inhibited by 0.1-0.3 mumol of Metyrapone and SKF 12185. These results allow to underline that the adrenals of rat and mouse, two species commonly used in laboratory experiments, may be used for in vitro investigations on cortisol metabolism from exogenous radioactive precursors.     

Suppressive effect of cyclosporin A on the development of Leishmania tropica-induced lesions in genetically susceptible BALB/c mice

The effect of cyclosporin A (CyA) application on the development of cutaneous lesions was analyzed in genetically susceptible BALB/c mice infected s.c. with Leishmania tropica promastigotes. Daily i.p. injections of CyA, beginning 2 days before or at the day of the infection, dose dependently inhibited the development of parasite-induced lesions; no effect on the lesions was observed, however, if CyA application was started 14 days after the infection. Cessation of CyA administration after having successfully suppressed the cutaneous lesions for a period of 42 days, resulted in the development of lesions within 3 days. CyA had no inhibitory effect on lesions developing in L. tropica infected hypothymic BALB/c nu/nu mice. CyA or CyA-containing mouse serum did not directly affect the viability and the growth rate of L. tropica promastigotes, suggesting that the effect of the agent was imposed on the cells participating in the formation of the cutaneous lesions. Quantitative analysis of the cell distribution in the spleens of infected mice revealed that CyA markedly suppressed the infection-associated numerical increase of splenocytes. Within the Thy-1+ lymphocyte compartment, CyA had its most pronounced effect on the Lyt-1+ T lymphocyte subset. Early in the disease, the frequency of splenic cells proliferating in response to L. tropica antigen in vitro was clearly inhibited by CyA; in the later stages of the infection, however, this effect could not be observed, indicating the presence of L. tropica-inducible T cells being relatively resistant to CyA. Taken together, our findings indicate that CyA reversibly inhibits or delays the parasite-induced expansion of Lyt-1+ splenic T lymphocytes, and thus suppresses the biological function of those T cells that are instrumental for the formation of cutaneous lesions in L. tropica-infected BALB/c mice.     

Novel Miscanthus hybrids: Modelling productivity on marginal land in Europe using dynamics of canopy development determined by light interception

New biomass crop hybrids for bioeconomic expansion require yield projections to determine their potential for strategic land use planning in the face of global challenges. Our biomass growth simulation incorporates radiation interception and conversion efficiency. Models often use leaf area to predict interception which is demanding to determine accurately, so instead we use low-cost rapid light interception measurements using a simple laboratory-made line ceptometer and relate the dynamics of canopy closure to thermal time, and to measurements of biomass. We apply the model to project the European biomass potentials of new market-ready hybrids for 2020–2030. Field measurements are easier to collect, the calibration is seasonally dynamic and reduces influence of weather variation between field sites. The model obtained is conservative, being calibrated by crops of varying establishment and varying maturity on less productive (marginal) land. This results in conservative projections of miscanthus hybrids for 2020–2030 based on 10% land use conversion of the least (productive) grassland and arable for farm diversification, which show a European potential of 80.7–89.7 Mt year⁻¹ biomass, with potential for 1.2–1.3 EJ year⁻¹ energy and 36.3–40.3 Mt year⁻¹ carbon capture, with seeded Miscanthus sacchariflorus × sinensis displaying highest yield potential. Simulated biomass projections must be viewed in light of the field measurements on less productive land with high soil water deficits. We are attempting to model the results from an ambitious and novel project combining new hybrids across Europe with agronomy which has not been perfected on less productive sites. Nevertheless, at the time of energy sourcing issues, seed-propagated miscanthus hybrids for the upscaled provision of bioenergy offer an alternative source of renewable energy. If European countries provide incentives for growers to invest, seeded hybrids can improve product availability and biomass yields over the current commercial miscanthus variety.     

Neue Formen vonAsperula scutellaris Vis. und ihre morphologisch-geographische und klimatische Bedeutung

Zusammenfassung Die ArtAsperula scutellaris Vis. wurde diagnostisch erweitert und genauer präzisiert. Sie zerfällt in folgende Sippen: die typische Form ssp.illyrica Korica, welche zwei Varietäten umfaßt (var.veleensis Korica und var.montenegrina Korica), und ssp.ramiflora Korica mit einer Varietät (var.albanica Korica).Asperula scutellaris Vis. ist ein mediterran-illyrischer Endem und einer der bemerkenswertesten Vertreter der jugoslawischen und albanischen Karstflora. Im mittleren Teil Albaniens tritt sie auch auf Serpentinen auf.In pflanzengeographischem Sinn sind vier Entwicklungsgebiete dieser Art zu unterscheiden: das Entwicklungsgebiet der Veleplanina in der Herzegowina (var.veleensis), das montenegrinische Entwicklungsgebiet (var.montenegrina) mit dem ursprünglichen Ausbildungszentrum in der weiteren Umgebung der Stadt Cetinje, endlich das nordalbanische Entwicklungsgebiet im Stromgebiet der Flüsse Cijevna und Drim. Diese drei Gebiete sind von submediterranem Charakter, das mittelalbanische Entwicklungsgebiet in der Gegend des Flusses Shkumbi (var.albanica) weist dagegen einen mediterranisch-submediterranischen Charakter auf.Auf Grund der festgestellten Tatsachen des heutigen Standes der Verbreitung der einzelnen Sippen dieser Art sowie auf Grund der charakteristischen geomorphologischen und klimatischen Differenzen zwischen den monomorphen Sippen (ssp.illyrica), welche an die Küstenteile des beschriebenen Areals gebunden sind, und den polymorphen Übergangsformen der submediterranen Sippen, welche in den kontinentalen Teilen des Areals überwiegen (submediterrane klimatische Einflüsse), folgt, daß die typischen Formen (ssp.illyrica) im submediterranen Gebiet phylogenetisch nicht mit jenen des mediterranen Gebietes identisch sind.     

Paraquat effect on the bioelectric parameters of the rabbit small intestine and its in vitro penetration

The effect of paraquat (in concentrations of 10(-4) and 10(-3) mol/l) was studied on the bioelectric parameters of rabbit small intestine. A short-lasting rise in the potential difference (PD) and some decrease of tissue resistance (R) were observed, particularly after the higher concentration. These changes indicate stimulation of the transport function of the rabbit small intestine as a result of administration of this herbicide. Other tested parameters included determination of the rate of paraquat penetration (at concentration gradient 10(-3) mol/l) across the intestinal wall from the serosal side to the mucosal side and conversely. In the latter case three experimental models were used: first--complete intestinal wall, second--intestinal wall with the serosa stripped off, and third--intestinal wall with the mucosa and serosa removed. Differences were found in these rates depending on the model used. The importance of epithelial cells of the mucosa and subepithelial layers, and mesothelium of the serosa in limiting the penetration of bipirydylium herbicides is stressed.     

Theoretical investigations on circular and chain-like hydrogen bonded structures found in two crystal forms of α-cyclodextrin hexahydrate: Models for hydration and water clusters

Hydration of macromolecules and the structure of water of crystallization are not understood in detail because in these complex systems. H-atoms cannot be located and the hydrogen bonding schemes are not known. X-ray and neutron diffraction studies on a hydrated oligosaccharide, α-cyclodextrin 6H₂O, ((C₆H₁₀O₅)₆·6H₂O), crystals forms A and B, gave insight into the chain-like and circular arrangement of hydrogen bonds. In the circles, homodromic (unidirectional) and antidromic (counter-running) orientation of five to six hydrogen bounds is observed. PCILO calculations showed that homodromic circles and chains are approx. 8% per hydrogen bond more stable than antidromic circles, that the changes in electronic charges on H and O atoms are greater in homo than in antidromic systems and that the dipole moments are only approx. 3 D in the homodromic circles but 6–8 D in chain-like and antidromic arrangement. These results have been interpreted in terms of cooperative effect. Circular systems are considered as structural elements in hydration shells of macromolecules and in the assembly of ‘flickering’ water clusters.     

Amphipod crustaceans as an important component of zoobenthos of the shallow Antarctic sublittoral

Benthic quantitative samples were taken in 1988 in the soft bottom sublittoral of Admiralty Bay (King George Island, South Shetlands) using a Tvärminne-type bottom sampler and SCUBA-diving technique at 7 successive stations situated at depths from 4 to 30 m.Dominant animal groups in terms of abundance were Amphipoda, Polychaeta and Bivalvia, whereas in terms of biomass Echinoidea were also dominant. Amphipod crustaceans clearly dominated the zoobenthos at depths from 10 to 25 m (the numerical share surpaising 60%) with maximal abundance of abt. 17 000 ind m^–2; in terms of biomass at specific depths amphipods occupied the 1st, 2nd or 3rd place with maximal biomass of abt. 100 g m^–2 where the maximal total biomass of zoobenthos reached 260 g m^–2 (10 m).Amphipoda were the most diversified group with some 35 taxa belonging to 14 families. Most species belonged to Eusiridae s.l. and Lysianassidae s.l. Dominant forms were Pontogeneiella brevicornis, Prostebbingia gracilis, Schraderia gracilis, Hippomedon kergueleni, Orchomenella cf. ultima, Cardenio paurodactylus and Paraphoxus rotundifrons.     

Bi-directional modulation of fast inhibitory synaptic transmission by leptin

The hormone leptin has widespread actions in the CNS. Indeed, leptin markedly influences hippocampal excitatory synaptic transmission and synaptic plasticity. However, the effects of leptin on fast inhibitory synaptic transmission in the hippocampus have not been evaluated. Here, we show that leptin modulates GABA_A receptor-mediated synaptic transmission onto hippocampal CA1 pyramidal cells. Leptin promotes a rapid and reversible increase in the amplitude of evoked GABA_A receptor-mediated inhibitory synaptic currents (IPSCs); an effect that was paralleled by increases in the frequency and amplitude of miniature IPSCs, but with no change in paired pulse ratio or coefficient of variation, suggesting a post-synaptic expression mechanism. Following washout of leptin, a persistent depression (inhibitory long-lasting depression) of evoked IPSCs was observed. Whole-cell dialysis or bath application of inhibitors of phosphoinositide 3 (PI 3)-kinase or Akt prevented leptin-induced enhancement of IPSCs indicating involvement of a post-synaptic PI 3-kinase/Akt-dependent pathway. In contrast, blockade of PI 3-kinase or Akt activity failed to alter the ability of leptin to induce inhibitory long-lasting depression, suggesting that this process is independent of PI 3-kinase/Akt. In conclusion these data indicate that the hormone leptin bi-directionally modulates GABA_A receptor-mediated synaptic transmission in the hippocampus. These findings have important implications for the role of this hormone in regulating hippocampal pyramidal neuron excitability.