Selection of indicative taxa for river habitats: a case study on benthic macroinvertebrates using indicator species analysis and the random forest methods

The aim of the study was to evaluate the exclusivity and/or preference of macroinvertebrate taxa for river habitats. Indicator species analysis and random forests methods were applied to the data set of macroinvertebrate samples taken from 58 sampling points. Samples were classified according to habitat types defined by the position in a river channel and local hydraulic characteristics. 86 macroinvertebrate taxa were included in the analyses. High indicative values for habitats (importance value ≥50 and/or indicator value ≥40) were identified for 26 taxa. The results of both methods can be considered similar. Merged habitats of channel margin (margin of main channel and side arms) were mainly defined by “negative” indicator taxa (correct classification of given samples was caused by non-occurrence and low abundances of certain taxa in this habitat). In general, there was only a small group of taxa preferring these habitats. Taxa were not fully habitat specific because they mostly occurred in two or three habitat types. This could be the result of autecological plasticity of individual taxa and the connectivity among habitats. According to the experience from this case study, it can be concluded that both random forests and IndVal methods are suitable for the detection of indicative species, and random forests method has some additional advantages.     

Mapping of repeated DNA sequences in plant chromosomes by PRINS and C-PRINS

 The primed in situ DNA labelling (PRINS) procedure was optimised for the rapid physical mapping of several types of repetitive DNA sequences on the mitotic chromosomes of Vicia faba, Pisum sativum and Secale cereale. A localization of the highly repeated FokI sequence on V. faba chromosomes was achieved after a 7-min total reaction time. In addition, we report a procedure for direct cycling-PRINS (C-PRINS), a variation of PRINS which involves a sequence of thermal cycles analogous to the polymerase chain reaction. Compared to PRINS, C-PRINS was more sensitive. Further work is needed to improve the sensitivity of the reaction to allow for the reliable detection of low-copy DNA sequences. Received: 17 September 1996 / Accepted: 18 October 1996     

Effect of Lipoprotein-X on lipid metabolism in rat kidney

Lipoprotein-X (Lp-X) is found in the plasma of patients with familiallecithin: cholesterol acyltransferase (LCAT) deficiency syndromes. Themajority of the patients with this disorder develop progressiveglomerulosclerosis. In this study, the effect of Lp-X on lipid metabolism inperfused rat kidney was investigated. Lp-X was isolated from plasma ofpatients with familial LCAT deficiency by sequential ultracentrifugation andgel filtration column chromatography. Rat kidneys were perfused for 1-2 hwith Krebs-Henseleit buffer containing 20 µM [1-14C]acetate or 20µM [Me-3H]choline. In the presence of Lp-X, no significant differencein the incorporation of radioactivity into triglycerides, cholesterol,phosphocholine, CDP-choline and sphingomyelin was observed. However,incorporation of radioactivity into cholesteryl esters andphosphatidylcholine was significantly elevated in Lp-X perfused kidneys. Thecontents of cholesterol, cholesteryl esters and phosphatidylcholine werealso significantly increased in Lp-X perfused kidneys. The increase in lipidcontent in the Lp-X perfused kidney is attributed to the direct depositionof Lp-X lipids into the organ. The increase in the labelling of cholesterylesters was attributed to the increase of available substrate (cholesterol)for the acyl-CoA:cholesterol acyltransferase (ACAT) reaction. The increasein phosphatidylcholine labelling was caused by a reduced turnover of thenewly synthesized labelled phosphatidylcholine during Lp-X perfusion.     

Ion channels and pores, made from scratch

We elaborate on the structural diversity well beyond the biological limitations that becomes accessible with synthetic ion channels and pores, and on the importance of advanced nanoarchitecture to create significant function.     

Effects of lactoferrin feeding on growth, feed intake and health of calves

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

A comparison of reactivating efficacy of newly developed oximes (K074, K075) and currently available oximes (obidoxime, HI-6) in cyclosarin-and tabun-poisoned rats

The potency of newly developed oximes (K074, K075) and commonly used oximes (obidoxime, HI-6) to reactivate nerve agent-inhibited acetylcholinesterase was evaluated in rats poisoned with tabun or cyclosarin at a lethal dose corresponding to the LD50 value. In vivo determined percentage of reactivation of tabun-inhibited blood and brain acetylcholinesterase showed that obidoxime is the most efficacious reactivator of tabun-inhibited acetylcholinesterase among studied oximes in the peripheral compartment (blood) although the differences between obidoxime and newly developed oximes were not significant. On the other hand, one of the newly developed oximes (K074) seems to be a significantly more efficacious reactivator of tabun-inhibited acetylcholinesterase in the central compartment (brain) than the other studied oximes. In addition, the oxime HI-6 is unable to sufficiently reactivate tabun-inhibited acetylcholinesterase in rats. In vivo determined percentage of reactivation of cyclosarin-inhibited blood and brain acetylcholinesterase in poisoned rats showed that HI-6 is the most efficacious reactivator of cyclosarin-inhibited acetylcholinesterase among the studied oximes in the peripheral (blood) as well as central (brain) compartment although the differences between the oxime HI-6 and other tested oximes in the brain were not significant. Due to their reactivating effects, both newly developed K-oximes can be considered to be promising oximes for the antidotal treatment of acute tabun poisoning while the oximes HI-6 is still the most promising oxime for the treatment of acute cyclosarin poisonings due to its high potency in reactivating cyclosarin-inhibited acetylcholinesterase in the peripheral as well as central compartment.     

Neurohumoral changes in chronic heart failure

Background: Humoral systems play an important role in the patophysiology and development of chronic heart failure (CHF). Methods: We conducted a search of neurohumoral activation in heart failure and its risk in the development of CHF. Results and conclusion: Neurohumoral factors may be divided into vasoconstrictive, vasodilative and cytokines. The main vasoconstrictive systems are the renin-angiotensin-aldosterone system (RAAS) and the sympathoadrenal system (SAS). Cytokines include tumour necrosis factor (TNF) alpha and interleukins. The systems of actions are interconnected and they mutually influence their secretion and activities. The possibilities of their detection and assessment for clinical purposes depend on their changes and kinetics in the organism and on the activity of individual metabolites. Apart from their vasoactive effects, the majority of humoral actions also interfere in the process of remodelling, function of the endothelium, blood elements, cardiomyocytes, cells of the smooth muscles, and in immunity as well as inflammatory processes. The rapid development of knowledge on the humoral actions in recent years has made possible their utilisation in diagnostics, treatment and prognosis.     

Grazer and virus-induced mortality of bacterioplankton accelerates development of Flectobacillus populations in a freshwater community

We present a detailed analysis of the effects of distinct bacterial mortality factors, viral lysis and heterotrophic nanoflagellates (HNF) bacterivory, associated with the development of filamentous Flectobacillus populations. Reservoir bacterioplankton communities were subjected to additions of both HNF and viruses together, or HNF alone, and then incubated in situ in dialyses bags. For distinct bacterial groups, mortality or growth stimulation was analysed by examining bacterial prey ingested in HNF food vacuoles with fluorescence in situ hybridization (FISH) and via FISH with microautoradiography (MAR-FISH). We also developed a semi-quantitative MAR-FISH-based estimation of relative activities of Flectobacillus populations (targeted by the R-FL615 probe). Bacterial groups vulnerable to HNF predation (mainly clusters of Betaproteobacteria), or discriminated against (Actinobacteria), were detected. Bacterial lineages most vulnerable to virus-lysis (mainly the Betaproteobacteria not targeted by the R-BT065 probe, of the Polynucleobacter cluster) were identified by comparing treatments with HNF alone to HNF and viruses together. Filaments affiliated with the Flectobacillus cluster appeared in both treatments, but were about twice as abundant, long and active as in incubations with viruses and HNF as compared with HNF alone. Viruses appeared to selectively suppress several bacterial groups, perhaps enhancing substrate availability thus stimulating growth and activity of filamentous Flectobacillus.     

Interleukin 6 signaling regulates promyelocytic leukemia protein gene expression in human normal and cancer cells

Tumor suppressor PML is induced under viral and genotoxic stresses by interferons and JAK-STAT signaling. However, the mechanism responsible for its cell type-specific regulation under non-stimulated conditions is poorly understood. To analyze the variation of PML expression, we utilized three human cell types, BJ fibroblasts and HeLa and U2OS cell lines, each with a distinct PML expression pattern. Analysis of JAK-STAT signaling in the three cell lines revealed differences in levels of activated STAT3 but not STAT1 correlating with PML mRNA and protein levels. RNAi-mediated knockdown of STAT3 decreased PML expression; both STAT3 level/activity and PML expression relied on IL6 secreted into culture media. We mapped the IL6-responsive sequence to an ISRE(-595/-628) element of the PML promoter. The PI3K/Akt/NFκB branch of IL6 signaling showed also cell-type dependence, being highest in BJ, intermediate in HeLa, and lowest in U2OS cells and correlated with IL6 secretion. RNAi-mediated knockdown of NEMO (NF-κ-B essential modulator), a key component of NFκB activation, suppressed NFκB targets LMP2 and IRF1 together with STAT3 and PML. Combined knockdown of STAT3 and NEMO did not further promote PML suppression, and it can be bypassed by exogenous IL6, indicating the NF-κB pathway acts upstream of JAK-STAT3 through induction of IL6. Our results indicate that the cell type-specific activity of IL6 signaling pathways governs PML expression under unperturbed growth conditions. As IL6 is induced in response to various viral and genotoxic stresses, this cytokine may regulate autocrine/paracrine induction of PML under these pathophysiological states as part of tissue adaptation to local stress.