Extracellular polysaccharidases synthesized by the epiphytic lichen Evernia prunastri (L.) Ach.

Evernia prunastri Ach., an epiphytic lichen growing on Quercus rotundifolia Lam., produces a -1,4-glucanase (EC 3.2.1.4) and a polygalacturonase (EC 3.2.1.15). The activity of these polysaccharidases increases as a response to incubation of the lichen with carboxymethylcellulose or sodium polygalacturonate, respectively. This increase in activity is thought to be the result of enzyme induction because it is inhibited by both cycloheximide and 8-azaguanine. Both polysaccharide-degrading enzymes are partially secreted into the incubation media.     

A new depside and two new diphenyl ether compounds from the lichen Ramalina farinacea (L.) Ach

The chemical investigation of the Vietnamese lichen Ramalina farinacea (L.) Ach. led to the isolation and the structure elucidation of eight compounds (1–8), including one new depside, formulated as methyl homosekikate (1) and two new diphenyl ethers, 3-(2-carboxy-5-methoxy-3-propylphenoxy)-2-hydroxy-4-methoxy-6-propylbenzoic acid, namely ramalinic acid A (2), and 3-(2-carboxy-5-methoxy-3-propylphenoxy)-2-hydroxy-4-methoxy-6-pentylbenzoic acid, namely ramalinic acid B (3). Their chemical structures were unambiguously determined by analysis of 1D and 2D NMR and high resolution ESI mass spectroscopic data, as well as by comparison with literature data. We also proposed a possible biosynthetic route for the formation of the two new diphenyl ethers (2) and (3) via an enzymatically induced intramolecular Smiles rearrangement of the depsides sekikaic acid and homosekikaic acid, respectively.     

Impact of anoxia and hydrogen sulphide on the metabolism of Arctica islandica L. (Bivalvia)

The effects of environmental anoxia and anoxic sulphide exposure on metabolism are measured in tissues of the clam, Arctica islandica. Under anoxia the total activity of glycogen phosphorylase and the percentage of the enzyme in the active a form are significantly reduced. Alterations in pyruvate kinase kinetics produce slightly increased V_max values, strongly increased S_0.5 PEP, slightly increased S_0.5 ADP in the muscular tissues and mantle, and strongly reduced I₅₀ for alanine (up to 90-fold increased sensitivity). Anoxia also stimulates a reduction of fructose-2,6-bisphosphate levels, an effector of phosphofructokinase, in all tissues tested. These effects are consistent with enzyme modifications induced by phosphorylation to produce a restricted activity. Anoxic sulphide exposure produced similar effects on the glycogenolytic enzyme glycogen phosphorylase (GP), as does anoxia alone. In the course of the experiments, mitochondrial energy metabolism is not affected by sulphide. The accumulation of the anaerobic indicator metabolite succinate is almost identical in adductor and foot under both stresses. The data suggest a similar coordinated metabolic rate control under environmental anoxia and anoxic sulphide exposure, i.e. H₂S has no distinctly different effects on the parameters tested. This study provides evidence that while being burrowed in anoxic sediments, the clams are able to withstand the detrimental effects of sulphide for a substantial period of time.     

Genetic transformation of cork oak (Quercus suber L.) for herbicide resistance

The bar gene was introduced into the cork oak genome. Cork oak embryogenic masses were transformed using the Agrobacterium strain AGL1 which carried the plasmid pBINUbiBar. This vector harbours the genes, nptII and bar, the latter under control of the maize ubiquitin promoter. The transgenic embryogenic lines were cryopreserved. Varying activities of phosphinothricin acetyl transferase were detected among the lines, which carried 1–4 copies of the insert. Molecular and biochemical assays confirmed the stability and expression of the transgenes 3 months after thawing the cultures. These results demonstrate genetic engineering of herbicide tolerance in Quercus spp. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Rubén álvarez, Ricardo J. Ordás are contributed equally.     

Effects of hypoxia and body size on the oxygen consumption of the bivalve Arctica islandica (L.)

The relationship between oxygen consumption and body weight has been examined in Arctica islandica (L.).Large Arctica exhibit a high degree of respiratory independence under hypoxic conditions; like other species studied, respiratory independence increases markedly with increasing body size. Respiratory independence can also be modified by temperature and physiological condition and it is concluded that the division of species per se into oxygen regulators and oxygen conformers is not merited. These terms describe only the extremes of what is a variable capacity to maintain respiratory independence during hypoxia.     

南美蟛蜞菊中的酚酸类化学成分

为了解南美蟛蜞菊[Wedelia trilobata (L.) Hitchc.]的化学成分, 从其全株中分离得到9 个酚酸类化合物。经光谱分析, 分别鉴定为6-乙酰基-7-羟基-2,3-二甲基色原酮 (1)、七叶内酯 (2)、丁香醛 (3)、5-羟甲基糠醛 (4)、对羟基苯甲酸 (5)、水杨酸 (6)、反式对羟基桂皮酸 (7)、咖啡酸甲酯 (8) 和反式咖啡酸 (9)。化合物1~8 为首次从该植物中分离得到。     

Factors Affecting Urease Activity in the Lichen Evernia prunastri (L.) Ach

In the lichen Evernia prunastri increased urease activity inthe presence of urea is enhanced by phosphate buffer and respirablereserves and decreased by desiccation. Although stimulatory,exogenous urea is not essential and may act as both an enzymeactivator and inducer. The previously observed decline in ureaseactivity on prolonged urea treatment, attributed to in vivoenzyme inactivation by phenolic lichen substances, is prevented,but not reversed, by in vitro additions of dithiothreitol. Evernia prunastri urease activity, enzyme inactivation, enzyme induction desiccation lichen     

Die FormenkreiseTurdus libonyanus (A. Sm.) undTurdus olivaceus L.

Ohne Zusammenfassung     

The impact of the 2003 summer drought on the intra-annual growth pattern of beech (Fagus sylvatica L.) and oak (Quercus robur L.) on a dry site in the Netherlands

Climate change is expected to result in more extreme weather conditions over large parts of Europe, such as the prolonged drought of 2003. As water supply is critical for tree growth on many sites in North-Western Europe, such droughts will affect growth, species competition, and forest dynamics. To be able to assess the susceptibility of tree species to climate change, it is necessary to understand growth responses to climate, at a high temporal resolution. We therefore studied the intra-annual growth dynamics of three beech trees (Fagus sylvatica L.) and five oak trees (Quercus robur L.) growing on a sandy site in the east of the Netherlands for 2 years: 2003 (oak and beech) and 2004 (oak). Microcores were taken at 2-week intervals from the end of April until the end of October. Intra-annual tree-ring formation was compared with prior and contemporary records of precipitation and temperature from a nearby weather station.The results indicate that oak and beech reacted differently to the summer drought in 2003. During the drought, wood formation in both species ceased, but in beech, it recovered after the drought. The causes of species-specific differences in intra-annual wood formation are discussed in the context of susceptibility to drought.     

Immunomodulating polysaccharides from the lichen Thamnolia vermicularis var. subuliformis

Three heteroglycans Ths-4, Ths-5 and thamnolan and a beta-glucan, Ths-2, isolated from the lichen Thamnolia vermicularis var. subuliformis were tested for in vitro immunomodulating activities and shown to have various influences on the immune system. All the polysaccharides except Ths-4 caused a stimulation of rat spleen cell proliferation. In contrast, Ths-4 caused cell death early in the culture, probably due to over-stimulation. Moreover, the galactofuranomannans, Ths-4, Ths-5 and the beta-glucan Ths-2, induced rat spleen cells to secrete IL-10 significantly above background levels. In addition, Ths-4 and Ths-5 stimulated significant TNF-alpha secretion by rat peritoneal macrophages. The galactofuranomannans Ths-4 and Ths-5 have similar structures apart from the molecular weight. Thus, it may be concluded that the molecular size might influence the potency but not the pattern of activity for Ths-4 and Ths-5. The galactofuranorhamnan thamnolan had less mitogenic effect than Ths-5 and Ths-2 and neither induced IL-10 secretion by rat spleen cells nor TNF-alpha secretion by peritoneal macrophages to significant levels. This shows that thamnolan with its unusual galactofuranorhamnan structure differs from the other Thamnolia polysaccharides in its immunomodulatory activity.     

Schneeammern (Passerina nivalis L.) und Zwergtrappe (Otis tetrax L.) in Krain 1914/1915

Ohne Zusammenfassung     

Furanoditerpenes from Arcangelisia flava (L.) Merr. and their antifungal activity

Two furanoditerpenes, 2α,3α-epoxy-2,3,7,8α-tetrahydropenianthic acid methyl ester (1) and 2α,3α-epoxy-2,3-dihydropenianthic acid methyl ester (2) were isolated and identified from the root of Arcangelisia flava (L.) Merr. The configuration of 1 was determined by X-ray crystallographic analysis and two-dimensional NMR. Fibraurin (3), fibleucin (4), 2β, 3α-dihydroxy-2,3,7,8α-tetrahydropenianthic acid-2,17-lactone (5), p-hydroxybenzaldehyde and vanillin were also isolated and identified by NMR and EI-MS or FAB-MS. The 2β, 3α-dihydroxy-2,3,7,8α-tetrahydropenianthic acid-2,17-lactone (5) showed the highest antifungal activity of the isolated five furanoditerpenes against a white-rot fungus (Trametes versicolor) and a brown-rot fungus (Fomitopsis palustris).