Biological control of pedological and hydro-geomorphological processes in a deciduous forest ecosystem

This study describes the effect of soil fauna and vegetation on the development of landscapes and how these actually control soil formation, geomorphological development and hydrological response. The study area is located in a semi-natural deciduous forest on marl in Luxembourg, with a strong texture contrast in the soil at 15–25 cm depth (luvic planosols). The methodology applied is both based on hydrological and geomorphological field measurements on runoff, sediment yield, perched water table dynamics, geomorphological survey, pedological survey and measurements related to in situ ectorganic horizon dynamics and litter decay, soil animal activity, as well as measurements of dynamic soil properties such as soil moisture and swelling and shrinkage. The results show that there is a positive feedback between tree type, soil fauna activity and the development of pipes, partial areas, soils and geomorphology. The landscape can be divided into two main types: Areas where Stellario-Carpinetum vegetation and partial areas are common and areas with Milio-Fagetum vegetation on dry slopes, which are differentiating more and more over time as a result of ongoing geo-ecosystem processes, and which also reflected in their sediment yield. The hydrological response is highly different for both landscape compartments as they are dominated by matrix (Beech) and pipe flow (Hornbeam) respectively. Soil fauna and tree type drive both soil and geomorphological evolution and they both can be considered as important ecosystem engineers.     

Design,RNA cleavage and antiviral activity of new artificial ribonucleases derived from mono-, di- and tripeptides connected by linkers of different hydrophobicity

A novel series of metal-free artificial ribonucleases (aRNases) was designed, synthesized and assessed in terms of ribonuclease activity and ability to inactivate influenza virus WSN/A33/H1N1 in vitro. The compounds were built of two short peptide fragments, which include Lys, Ser, Arg, Glu and imidazole residues in various combinations, connected by linkers of different hydrophobicity (1,12-diaminododecane or 4,9-dioxa-1,12-diaminododecane). These compounds efficiently cleaved different RNA substrates under physiological conditions at rates three to five times higher than that of artificial ribonucleases described earlier and displayed RNase A-like cleavage specificity. aRNases with the hydrophobic 1,12-diaminododecane linker displayed ribonuclease activity 3–40 times higher than aRNases with the 4,9-dioxa-1,12-diaminododecane linker. The assumed mechanism of RNA cleavage was typical for natural ribonucleases, that is, general acid-base catalysis via the formation of acid/base pairs by functional groups of amino acids present in the aRNases; the pH profile of cleavage confirmed this mechanism. The most active aRNases under study exhibited high antiviral activity and entirely inactivated influenza virus A/WSN/33/(H1N1) after a short incubation period of viral suspension under physiological conditions.     

Downscaling indicators of forest habitat structure from national assessments

Downscaling is an important problem because consistent large-area assessments of forest habitat structure, while feasible, are only feasible when using relatively coarse data and indicators. Techniques are needed to enable more detailed and local interpretations of the national statistics. Using the results of national assessments from land-cover maps, this paper demonstrates downscaling in the spatial domain, and in the domain of the habitat model. A moving window device was used to measure structure (habitat amount and connectivity), and those indicators were then analyzed and combined with other information in various ways to illustrate downscaling.     

Penicisimpins A⿿C,three new dihydroisocoumarins from Penicillium simplicissimum MA-332, a marine fungus derived from the rhizosphere of the mangrove plant Bruguiera sexangula var. rhynchopetala

Three new dihydroisocoumarin derivatives, penicisimpins A⿿C (1⿿3), were isolated and identified from Penicillium simplicissimum MA-332, a fungus derived from the rhizosphere of the marine mangrove plant Bruguiera sexangula var. rhynchopetala. Their structures and absolute configurations were elucidated by extensive spectroscopic methods in combination with X-ray diffraction experiment. Compounds 1⿿3 exhibited brine shrimp (Artemia salina) lethality as well as broad-spectrum antimicrobial activities.     

Anatomical site of pheromone accumulation and temporal pattern of pheromone emission in the ambrosia beetle Megaplatypus mutatus

Megaplatypus mutatus (Chapuis) is a native South American ambrosia beetle that attacks live hardwood trees (e.g. Populus spp.), causing important economic losses to commercial plantations. Male beetles release the main components of the sex pheromone, namely (+)‐6‐methyl‐5‐hepten‐2‐ol [(+)‐sulcatol, or retusol] and 6‐methyl‐5‐hepten‐2‐one (sulcatone), when colonizing suitable hosts. The hindgut is shown to be the anatomical site of pheromone accumulation within males, the enantiomeric composition of sulcatol in this tissue is 99%‐(+) and sulcatol is first detectable in this tissue on days 1–2 after gallery initiation. Peak accumulation of sulcatol occurs on days 5–12 after gallery initiation. Trace quantities of sulcatone are also observed during the same period. Both pheromone components are present in male emissions from three host species (Populus×canadensis, Populus alba and Casuarina stricta) between days 2 and 12 after gallery initiation, although sulcatone is always present in low concentrations. The temporal patterns of sulcatol and sulcatone accumulation or storage in male M. mutatus correspond to the temporal patterns of emission.     

Neurogenic relaxation mediated by vasoactive intestinal polypeptide (VIP) in the isthmus of the human fallopian tube

The smooth musculature of the Fallopian tube is important for normal ovum transport, fertilization and implantation. Little is known about the factors controlling the motor activity of the isthmic sphincter. Studies were performed on smooth muscle preparations from the human tube in vitro. Electrical field stimulation of the nerves in the isthmic region reduced the motor activity, particularly in the circular muscle. The response was unaffected by adrenergic and cholinergic antagonists, but blocked by tetrodotoxin, suggesting a neural involvement. Vasoactive intestinal polypeptide (VIP) was considered a likely candidate for the neural mediation of this response in view of the high density of VIP-containing nerve fibres in this region, and in view of the fact that exogenous VIP causes a marked reduction of the tubal motor activity. To test whether VIP might be the endogenous mediator of this effect, nerve stimulation was carried out in the presence of large amounts of exogenous VIP in order to occupy all VIP receptors; the motor inhibitory action of VIP was counteracted by vasopressin. Under these conditions, nerve stimulation failed to reduce isthmic motor activity. This was not due to vasopressin since reduction occurred in the presence of this peptide alone. The results suggest that VIP is responsible for the neurogenic inhibition of motor activity in the isthmus region of the human Fallopian tube.     

Cage experiments on Orius tantillus predation of Helicoverpa armigera

The role of Orius tantillus (Motschulsky) (Hemiptera: Anthocoridae) in the predation of H. armigera was studied on both sorghum (Sorghum bicolor L.) and pigeonpea (Cajanus cajan L.), the predominant intercrop of small farmers in Andhra Pradesh, India. Adult Orius tantillus was observed in cages where there were eggs and first-instar larvae of H. armigera on sorghum and pigeonpea. We found that O. tantillus had two diurnal peaks of activity, after sunrise and before sunset. O. tantillus was found preying on first-instar larvae and not on eggs. However, a later immunoassay of O. tantillus collected on sorghum during a peak period of H. armigera oviposition activity showed that predation of eggs did occur under certain conditions. The activity of O. tantillus on sorghum was significantly higher on the flowers than elsewhere but this was not the case on pigeonpea. Therefore O. tantillus was a significantly more efficient predator on sorghum than on pigeonpea. The results indicate that O. tantillus could be an important predator of early stages of an H. armigera infestation, particularly in sorghum.     

The Effects of the Porosity of a Support and of Attachment on the Mode of Action of Immobilized Endopolygalacturonase

Endopolygalacturonase of Aspergillus sp. was immobilized by three different methods; viz. (a) via amino groups, (b) via carboxyl groups and (c) by means of epoxy groups to a nonporous microparticular silicon dioxide (Cabosil), functionalized by 3-(amino)-propyl groups and 3-(2',3'-epoxypropoxy)-propyl groups, respectively. The conjugates were compared in their mode of action with corresponding immobilized preparations based on microporous ceramics. The binding via amino groups and via carboxyl groups lead, by itself, to changes in the mode of action of the enzyme, consisting of a decrease in randomness of glycosidic linkage splitting. The changes were greater in microporous support conjugates due to additional size-exclusion effects. The action pattern of endopolygalacturonase bound by means of epoxy groups was modulated exclusively by the porosity of the support, whereas the binding alone did not play any role.