Extracellular superoxide dismutase (EC-SOD) binds to type i collagen and protects against oxidative fragmentation

The antioxidant enzyme extracellular superoxide dismutase (EC-SOD) is mainly found in the extracellular matrix of tissues. EC-SOD participates in the detoxification of reactive oxygen species by catalyzing the dismutation of superoxide radicals. The tissue distribution of the enzyme is particularly important because of the reactive nature of its substrate, and it is likely essential that EC-SOD is positioned at the site of superoxide production to prevent adventitious oxidation. EC-SOD contains a C-terminal heparin-binding region thought to be important for modulating its distribution in the extracellular matrix. This paper demonstrates that, in addition to binding heparin, EC-SOD specifically binds to type I collagen with a dissociation constant (K(d)) of 200 nm. The heparin-binding region was found to mediate the interaction with collagen. Notably, the bound EC-SOD significantly protects type I collagen from oxidative fragmentation. This expands the known repertoire of EC-SOD binding partners and may play an important physiological role in preventing oxidative fragmentation of collagen during oxidative stress.     

Using drug-discrimination techniques to study the abuse-related effects of psychoactive drugs in rats

Drug-discrimination (DD) techniques can be used to study abuse-related effects by establishing the interoceptive effects of a training drug (e.g., cocaine) as a cue for performing a specific operant response (e.g., lever pressing reinforced by food). During training with this protocol, pressing one lever is reinforced when the training drug is injected before the start of the session, and responding on a second lever is reinforced when vehicle is injected before the session. Lever choice during test sessions can then be used as an indication of whether a novel drug has effects similar to the training drug, or whether a potential therapeutic alters the effects of the training drug. Although training can be lengthy (up to several months), the pharmacological specificity of DD procedures make them a perfect complement to other techniques used to study drug-abuse phenomena, such as intravenous self-administration and conditioned place-preference procedures.     

Membrane rafts: a potential gateway for bacterial entry into host cells

Pathogenic bacteria have developed various mechanisms to evade host immune defense systems. Invasion of pathogenic bacteria requires interaction of the pathogen with host receptors, followed by activation of signal transduction pathways and rearrangement of the cytoskeleton to facilitate bacterial entry. Numerous bacteria exploit specialized plasma membrane microdomains, commonly called membrane rafts, which are rich in cholesterol, sphingolipids and a special set of signaling molecules which allow entry to host cells and establishment of a protected niche within the host. This review focuses on the current understanding of the raft hypothesis and the means by which pathogenic bacteria subvert membrane microdomains to promote infection.     

Acaulospora alpina, a new arbuscular mycorrhizal fungal species characteristic for high mountainous and alpine regions of the Swiss Alps

Acaulospora alpina sp. nov. forms small (65-85 microm diam), dark yellow to orange-brown spores laterally on the neck of hyaline to subhyaline sporiferous saccules. The spores have a three-layered outer spore wall, a bi-layered middle wall and a three-layered inner wall. The surface of the second layer of the outer spore wall is ornamented, having regular, circular pits (1.5-2 microm diam) that are as deep as wide and truncated conical. A "beaded" wall layer as found in most other Acaulospora spp. is lacking. The spore morphology of A. alpina resembles that of A. paulinae but can be differentiated easily by the unique ornamentation with the characteristic pits and by the spore color. A key is presented summarizing the morphological differences among Acaulospora species with an ornamented outer spore wall. Partial DNA sequences of the ITS1, 5.8S subunit and ITS2 regions of ribosomal DNA show that A. alpina and A. paulinae are not closely related. Acaulospora lacunosa, which has similar color but has generally bigger spores, also has distinct rDNA sequences. Acaulospora alpina is a characteristic member of the arbuscular mycorrhizal fungal communities in soils with pH 3.5-6.5 in grasslands of the Swiss Alps at altitudes between 1800 and 2700 m above sea level. It is less frequent at 1300-1800 m above sea level, and it so far has not been found in the Alps below 1300 m or in the lowlands of Switzerland.     

Distribution of isoflavonoids in non-leguminous taxa - an update

Common emphasis of the fact that isoflavonoids are characteristic metabolites of leguminous plants sometimes leads to overlooking that the presence of isoflavonoids has been reported in several dozen other families. The spectrum of isoflavonoid producing taxa includes the representatives of four classes of multicellular plants, namely the Bryopsida, the Pinopsida, the Magnoliopsida and the Liliopsida. A review, recently published by Reynaud et al. [Reynaud, J., Guilet D., Terreux R., Lussignol M., Walchshofer N., 2005. Isoflavonoids in non-leguminous families: an update. Nat. Prod. Rep. 22, 504-515], provided listing of 164 isoflavonoids altogether reported in 31 non-leguminous angiosperm families. In this contribution we complement the abovementioned inventory bringing the references on further 17 isoflavonoid producing families and on additional 49 isoflavonoids reported to occur in non-leguminous plants.     

Linking Foliar Chemistry to Forest Floor Solid and Solution Phase Organic C and N in Picea abies [L.] Karst Stands in Northern Bohemia

Dissolved organic carbon and nitrogen (DOC and DON) produced in the forest floor are important for ecosystem functions such as microbial metabolism, pedogenesis and pollutant transport. Past work has shown that both DOC and DON production are related to litterfall and standing stocks of C and N in the forest floor. This study, conducted in spring, 2003, investigated variation in forest floor water extractable DOC (WEDOC) and DON (WEDON) and forest floor C and N as a function of lignin, cellulose and N contained in live canopy foliage across eight Picea abies [L.] Karst stands in northern Bohemia. Based on Near Infrared Spectroscopy (NIR) analysis of foliar materials, lignin:N and cellulose:N content of the youngest needles (those produced in 2002) were positively and significantly related to WEDOC (R² = 0.82–0.97; P<0.01) and to forest floor C:N ratio (R = 0.72–0.78; P<0.01). Foliar N was strongly and negatively related to WEDOC and C:N ratio (R = −0.91 and 0.72; P<0.05) among our study sites. WEDON was positively correlated to foliar lignin:N (R = 0.48; P<0.05; n=40). Forest floor C pools were not positively correlated with foliar lignin and cellulose and forest floor N pools were not positively correlated with foliar N. Instead, a significant negative correlation was found between forest floor N pools and foliar cellulose (R=−0.41; P<0.05), and between forest floor C pools and foliar N (R = −0.44; P<0.05). From a remote sensing standpoint, our results are important because canopy reflectance properties are primarily influenced by the most recent foliage, and it was the chemistry of the most recently produced needles that showed a stronger relationship with forest floor WEDOC and C:N ratio suggesting forest floor production of WEDOC can be calculated regionally with remote sensing.     

Long-term change of the littoral Cladocera in the Tatra Mountain lakes through a major acidification event

In our study, we focused on littoral Cladocera living and feeding in shallow shore parts of 46 mountain lakes in the Tatra Mountains (Slovakia and Poland). The studied lakes underwent a major acidification event in the 1980s and are now in the process of recovery. Lakes were divided into three categories based on their sensitivity to acidification: 5 extremely sensitive (ES), 11 acid sensitive (AS), and 30 non-sensitive (NS) lakes. In our study, we included historical data from the literature, and data from sediment core and littoral samples, which together represent the evolution of the littoral communities from a pre-industrial period up to the present. In total, 11 littoral species were found belonging to three cladoceran families. Most of the species were members of the family Chydoridae: Alona affinis, A. quadrangularis, A. rectangula, A. guttata, Acroperus harpae, Alonella excisa, A. nana, Chydorus sphaericus, and Eurycercus lamellatus. One species belonged to each family Daphniidae (Ceriodaphnia quadrangula) and Polyphemidae (Polyphemus pediculus). The most numerous littoral taxa were Alona affinis, Acroperus harpae, and Chydorus sphaericus. All species reacted to decreased pH levels during peak acidification in the 1980s by disappearing from most of the lakes of all categories; the only persisting species was Chydorus sphaericus. Most species returned to the lakes when pH started to increase in the 1990s, although their return was noticeably slower in AS lakes. Alona quadrangularis decreased its distribution range over the studied period; Polyphemus pediculus was mostly detected in the 1910s only. The number of species was highest in all lake categories when dwarf pine was present in the lake catchment. On the whole, the littoral community was richest in NS lakes.     

Littoral benthic macroinvertebrates of mountain lakes in the Tatra Mountains (Slovakia,Poland)

Littoral benthic macroinvertebrates of 45 mountain lakes in the Tatra Mountains were sampled using a semi-quantitative method in September 2000. A total of 32,852 specimens were identified to 93 taxa belonging to 14 higher taxonomic groups. Multivariate statistics (CCA, RDA) and nine biotic metrics (AQEM/STAR) were used to explain relationships between macroinvertebrate assemblages and environmental variables. Up to 57% of the ecological position of littoral macroinvertebrate assemblages were explained by variance of environmental variables divided into chemical, trophic, physical, catchment and location. Five types of Tatra lakes were recognized using CCA: A — strongly acidified lakes (small catchment, low pH, high concentration of TP, DOC, highest amount of POM in littoral); B — alpine acidified lakes (low amount of POM, low values of biotic metrics); C — alpine non-acidified lakes (high value of diversity index, predominance of Diptera); D — subalpine acidified lakes (high values of biotic metrics: number of families, proportion of crenal and rhithral taxa/total taxa); E — subalpine non-acidified lakes (high values of biotic metrics: number of families, number of genera, BMWP score, number of taxa and abundance of EPT taxa). RDA was used to design five levels of macroinvertebrate taxa acidification tolerance. The Tatra Acidification Index (TAI) was established to assess the acidification status of the lakes in the Tatra Mts.     

Chemical composition of the Tatra Mountain lakes: Response to acidification

Data from two surveys of the Tatra Mountain lakes (Slovakia and Poland) performed in the autumns of 1984 (53 lakes) and 1993 or 1994 (92 lakes) were used to estimate spatial variability in water chemistry in this lake district during the period of maximum European acid deposition. The ionic content of the lakes was generally low, with conductivity (at 20°C) ranging from 1.1 to 4.7 mS m^?1 and 23% of the lakes had a depleted carbonate buffering system. Major factors governing differences in lake-water chemistry were bedrock composition and amount of soil and vegetation in their catchment areas. Compared to lakes in the predominantly granitic central part of the Tatra Mountains, lakes in the West Tatra Mountains had higher concentrations of base cations and alkalinity due to the presence of metamorphic rocks in the bedrock. Concentrations of phosphorus, organic carbon, organic nitrogen, and chlorophyll-a were highest in forest lakes and decreased with decreasing density of vegetation and soil cover in the catchment areas. Concentrations of nitrate showed an opposite trend. Several exceptions to these general patterns in chemical and biological composition were due to exceptional geology or hydrology of the lake catchments.