Production of extracellular enzymes and cyclosporin byTolypocladium inflatum and morphologically related fungi

Summary Tolypocladium inflatum, the producer of cyclosporins, and morphologically related fungi from the generaTolypocladium, Beauveria, Fusarium andNeocosmospora produced different levels of cyclosporin A and of extracellular lipase and chitinase. However, entomopathogenically important protease activity was not detected.     

Prey depletion by the foraging of the Eurasian treecreeper, Certhia familiaris, on tree-trunk arthropods

We examined to what extent breeding insectivorous treecreepers, Certhia familiaris, affect the abundance and the mean size of their prey population on the surface of tree trunks. In order to determine foraging pressure on tree trunks, we observed the parent birds' foraging behaviour in marked squares (25Ꭱ m) at a short (10 m) and long distance (90 m) from the nest, when the nestlings were near fledging. Immediately after fledging, we measured the remaining food abundance on a sample of tree trunks near to and far from the nest. All arthropods longer than 1 mm were collected and identified to family level and their length was measured. Treecreepers foraged for significantly less time on trunks far from the nest than on trunks close to the nest (5 s vs 186 s). Consequently, treecreepers were found to deplete food abundance on trunks close to the nest. During the nesting period, parent birds removed almost twice as many spiders and other arthropods (excluding Formica ants) from the tree trunks close to the nest than from those further away. The size distribution of arthropods was the same between frequently and seldom-used tree trunks, suggesting that arthropod consumption by treecreepers was not size selective. Our direct measurements on the abundance of arthropods provide rare evidence for the ability of predators to deplete their food resources to a large extent.     

Synthesis and CB1 receptor activities of novel arachidonyl alcohol derivatives

Novel derivatives of arachidonyl alcohol were synthesized and evaluated for their CB1 receptor activity by [(35)S]GTP(gamma)S assay using rat cerebellar membranes.     

Species richness and regional distribution of myrmecophilous beetles

Four major hypotheses have been put forward to explain local species richness of commensal or parasitic species. The resource distribution hypothesis predicts that regionally widespread host species are able to support higher local species richness of commensals or parasites. On the other hand, the resource size hypothesis predicts that larger hosts can support more species than smaller hosts, and comparably, the resource abundance hypothesis predicts that hosts that offer more resources are able to support more species. Finally, the resource concentration hypothesis predicts that hosts that occur in high-density patches support higher species richness. In this study, we tested the first three of the above hypotheses with myrmecophilous beetles and their host ants. In addition to species richness of myrmecophilous beetles, we also applied the above hypotheses to explain the distribution of the beetles. Our data are exclusively based on an extensive literature survey. Myrmecophilous beetles live in naturally fragmented environments composed of host ant colonies and they are exclusively dependent on ants. We found that the distribution of the host ants and the colony size of the host ants had a positive effect on both the species richness and the distribution of myrmecophilous beetles. In the same way, we found that myrmecophilous beetle species that are generalists, i.e. have more than one host ant species, and thus have more abundant resources, were more widely distributed than specialist species. Thus, we found support for the hypothesis that resource distribution, resource size and resource abundance have an effect on species richness and on the distribution of species.     

Urinary excretion of lignans after administration of isolated plant lignans to rats: the effect of single dose and ten-day exposures

The difference in urinary excretion of mammalian and plant lignans in rats was determined after oral administration of equivalent doses (25 mg/kg of body weight) of 7-hydroxymatairesinol (HMR), lariciresinol (LAR), matairesinol (MR), and secoisolariciresinol (SECO). Twenty-four hours-urine samples were collected after a single dose and after administration of one dose/day for 10 days. Eight lignans were analysed in urine extracts using a high-performance liquid chromatography-tandem mass spectrometry method showing good sensitivity and repeatability. After a single dose of HMR, LAR, MR, and SECO, the main metabolites were 7-hydroxyenterolactone (HENL), cyclolariciresinol (CLAR), enterolactone (ENL), and enterodiol (END), respectively, but after 10-day exposure ENL was the main metabolite of all the tested lignans, showing a considerably higher excretion than after a single dose. Metabolic transformations of plant lignans into each other could also be observed.     

Lipid metabolism in the adipose tissues of a carnivore, the raccoon dog, during prolonged fasting

Previous studies on laboratory rodents, rabbits, and humans have demonstrated that adipose tissue fatty acid (FA) mobilization is selective, and its efficiency is related to the molecular structure of FAs. This study was undertaken to find out whether such preferences of FA mobilization are a general feature of mammalian white adipose tissue (WAT) and are also manifested in carnivores. Fractional mobilization of a wide spectrum of FAs was studied by gas-liquid chromatography from six subcutaneous (scapular, rump, ventral) and intra-abdominal (omental, mesenteric, retroperitoneal) WAT depots of raccoon dogs (Nyctereutes procyonoides) fed or fasted for 2 months. Fasting stimulated the mobilization of shorter-chain saturated, mono-unsaturated (MUFAs), and polyunsaturated FAs (PUFAs). The effects of unsaturation and the position of the first double bond from the methyl end were more inconsistent. The effect of double-bond position may be due to chain shortening of longer-chain MUFAs and preferential utilization of n-3 PUFAs over n-6 PUFAs. Moreover, there were site-specific differences in fractional mobilization, the omental adipose tissue being the most divergent. The in vivo FA mobilization from the regional WAT depots of a carnivore was selective, and the molecular structure of the FA affected its efficiency.     

Internal and external loading as regulators of nutrient concentrations in the agriculturally loaded Lake Pyhäjärvi (southwest Finland)

This study assesses the effects of external and internalloading on the nutrient concentrations in an agriculturallyloaded shallow lake. Using 13 years of observations of thelake's input and outflow, we calculated the long-term balancesof Tot-P and Tot-N. A more detailed balance, which includeddissolved nutrients and suspended solids, was estimated for anice-free period of one year. The contribution of the externalload was assessed using a mass-balance model. The internalload was estimated from the nutrient balances and on the basisof sedimentation measurements and bioassays. The drainagebasin of the lake provided most of the external nutrientinput; the remaining load was derived from atmosphericdeposition to the lake. The proportions of river-transported Pand N in dissolved form were 25% and 77%, respectively. Thelake retained >80% of the external load. Particulatenutrients settled to the bottom and were probably resuspendedseveral times before permanent sedimentation. Dissolvednutrients were bound by primary producers and a highproportion of dissolved P was removed with the fish catch.Dissolved N was also lost via denitrification. Themass-balance model showed that external loading only partlyregulated the mean annual nutrient concentrations in the lake.The regulation was probably due to internal loading, which washigh despite the efficient net retention of nutrients. Duringthe ice-free period, the temporal variations in nutrientconcentrations were controlled almost solely by internalprocesses, such as resuspension of inorganic and organicbottom matter. Although the internal load of bioavailable Pmay, under favourable conditions, exceed the external load,the mechanism by which bioavailable P is translocated from thebottom sediments to the water could not be fully identified.Abbreviations used in this paper follow the editor'srules.     

Effects of elevated ultraviolet-B radiation on a plant–herbivore interaction

Enhanced ultraviolet-B (UV-B) radiation may have multiple effects on both plants and animals and affect plant–herbivore interactions directly and indirectly by inducing changes in host plant quality. In this study, we examined combined effects of UV-B and herbivory on the defence of the mountain birch (Betula pubescens ssp. czerepanovii) and also the effects of enhanced UV-B radiation on a geometrid with an outbreak cycle: the autumnal moth (Epirrita autumnata). We established an experiment mimicking ozone depletion of 30% (a relevant level when simulating ozone depletion above Northern Lapland). Both arctic species responded only slightly to the enhanced level of UV-B radiation, which may indicate that these species are already adapted to a broader range of UV-B radiation. UV-B exposure slightly induced the accumulation of myricetin glycosides but had no significant effect on the contents of quercetin or kaempferol derivatives. Mountain birch seedlings responded more efficiently to herbivory wounding than to enhanced UV-B exposure. Herbivory induced the activities of foliar oxidases that had earlier been shown to impair both feeding and growth of moth larvae. In contrast, the contents of foliar phenolics did not show the same response in different clones, except for a decrease in the contents of tannin precursors. The induction of foliar phenoloxidase activities is a specific defence response of mountain birches against insect herbivory. To conclude, our results do not support the hypothesis that the outbreak cycle of the autumnal moth can be explained by the cycles of solar activity and UV-B.     

Murine cathepsin D deficiency is associated with dysmyelination/myelin disruption and accumulation of cholesteryl esters in the brain

Cathepsin D (CTSD) deficiencies are fatal neurological diseases that in human infants and in sheep are characterized by extreme loss of neurons and myelin. To date, similar morphological evidence for myelin disruption in CTSD knockout mice has not been reported. Here, we show that CTSD deficiency leads to pronounced myelin changes in the murine brain: myelin-related proteolipid protein and myelin basic protein were both markedly reduced at postnatal day 24, and the amount of lipids characteristically high in myelin (e.g. plasmalogen-derived alkenyl chains and glycosphingolipid-derived 20- and 24-carbon acyl chains) were significantly lowered compared with controls. These changes were accompanied by ultrastructural alterations of myelin, including significant thinning of myelin sheaths. Furthermore, in CTSD knockout brains there was a pronounced accumulation of cholesteryl esters and abnormal levels of proteins related to cholesterol transport, with an increased content of apolipoprotein E and a reduced content of ATP-binding cassette transporter A1. These results provide evidence for dysmyelination and altered trafficking of cholesterol in brains of CTSD knockout mice, and warrant further studies on the role of lipid metabolism in the pathogenesis of CTSD deficiencies.