Size, activity and catabolic diversity of the soil microbial biomass in a wetland complex invaded by reed canary grass

Reed canary grass (Phalaris arundinacea, L.) invasion of wetlands is an ecological issue that has received attention, but its impact on soil microbial diversity is not well documented. The present study assessed the size (substrate-induced respiration), catabolic diversity (CLPP, community level physiological profiles) and composition (selective inhibition) of the soil microbial community in invaded (>95% P. arundinacea cover) and in non-invaded areas of a wetland occupied by native species grown either as a mixed assemblage (22 species) or as quasi-monotypic stands of Scirpus cyperinus (74% cover). The study also tested the hypothesis that decomposition of lignin- and phenolics-rich plant tissues would be fastest in soils exhibiting high catabolic diversity. Results showed that soil respiration, microbial biomass and diversity were significantly higher (P?<?0.03; 1.5 to 3 fold) in P. arundinacea-invaded soils than in soils supporting native plant species. Fungal to bacterial ratios were also higher in invaded (0.6) than in non-invaded (0.4) plots. Further, canonical discriminant analysis of CLPP data showed distinct communities of soil decomposers associated with each plant community. However, these differences in microbial attributes had no effect on decomposition of plant biomass which was primarily controlled by its chemical composition. While P. arundinacea invasion has substantially reduced plant diversity, this study found no parallel decline in the size and diversity of the soil microbial community in the invaded areas.     

Networks of neurons coupled to microelectrode arrays: a neuronal sensory system for pharmacological applications

Two main features make microelectrode arrays (MEAs) a valuable tool for electrophysiological measurements under the perspective of pharmacological applications, namely: (i) they are non-invasive and permit, under appropriate conditions, to monitor the electrophysiological activity of neurons for a long period of time (i.e. from several hours up to months); (ii) they allow a multi-site recording (up to tens of channels). Thus, they should allow a high-throughput screening while reducing the need for animal experiments. In this paper, by taking advantages of these features, we analyze the changes in activity pattern induced by the treatment with specific substances, applied on dissociated neurons coming from the chick-embryo spinal cord. Following pioneering works by Gross and co-workers (see e.g. Gross and Kowalski, 1991. Neural Networks, Concepts, Application and Implementation, vol. 4. Prentice Hall, NJ, pp. 47-110; Gross et al., 1992. Sensors Actuators, 6, 1-8.), in this paper analysis of the drugs' effects (e.g. NBQX, CTZ, MK801) to the collective electrophysiological behavior of the neuronal network in terms of burst activity, will be presented. Data are simultaneously recorded from eight electrodes and besides variations induced by the drugs also the correlation between different channels (i.e. different area in the neural network) with respect to the chemical stimuli will be introduced (Bove et al., 1997. IEEE Trans. Biomed. Eng., 44, 964-977.). Cultured spinal neurons from the chick embryo were chosen as a neurobiological system for their relative simplicity and for their reproducible spontaneous electrophysiological behavior. It is well known that neuronal networks in the developing spinal cord are spontaneously active and that the presence of a significant and reproducible bursting activity is essential for the proper formation of muscles and joints (Chub and O'Donovan, 1998. J. Neurosci., 1, 294-306.). This fact, beside a natural variability among different biological preparations, allows a comparison also among different experimental session giving reliable results and envisaging a definition of a bioelectronic 'neuronal sensory system'.     

Study on the synthesis of complement components by human renal mesangial cells in culture. Assessment of the effect of cytokines

Renal mesangial cell (MC) cultures are easily established and widely used. MC produce some complement (C) regulatory proteins. We studied whether MC synthesize C components (C3, C5, C8). MC cultures were established from normal portions of cortices of nephrectomies for renal cancer. After growing to near-confluence in RPMI/17% FBS and resting for 24 h in RPMI/0.5% FBS, MC were stimulated up to 72 h with IL-1 or IL-6 (10, 100, 1000 U/ml). Neither C5 nor C8 were detected by ELISA. While C3 was present in supernatant under basal conditions (15.5–107.6 ng/10⁶ cells/24h) in different MC lines. IL-1 up-regulated the synthesis by 2.4–4.5 folds, whereas IL-6 did not show any effect. C3 synthetic rate was 1,76 ng/h/10⁶ cells under IL-1 stimulation versus basal rate of 0,37 ng/h/10⁶ cells. MC production of C3, especially induced by IL-1 may have pathogenetic relevance in glomerulonephritis.     

Analysis of molybdenite bioleaching by Thiobacillus ferrooxidans in the absence of iron (II)

Summary Thiobacillus ferrooxidans attachment on MoS² and Mo dissolution are increased by the addition of the tensioactive agent Tween 80 in absence of iron(II), which suggests that the poor bioleaching of MoS² is caused by its hydrophobic character. Additionally, inhibition ofThiobacillus ferrooxidans growth by the presence of MoO₄ ^2– and the effect of variable amounts of Tween 80 on bacteria growth and on MoS² bioleaching are considered in this paper. Data confirm the need of bacterial attachment to insoluble substrate for bioleaching by the direct mechanism.     

Temporal relationships between DNA metabolism and the growth-inhibitory response produced by dexamethasone in rat glioma cell cultures

Summary The temporal relationships between aspects of DNA metabolism and the suppression of cell proliferation were investigated in rat glioma (strain C6) monolayer cultures exposed to 10μM dexamethasone. Cell densities (cell number per cm²), rates of DNA synthesis (dpm of [³H]thymidine incorporated per μg DNA per min), and cellular DNA (μg DNA per cm²) were measured daily in control and dexamethasone-treated cultures over a 3-day period. The percentage of cells in metaphase and the proportion of metaphases containing >2n(42) chromosomes also were determined in control and treated cultures. When log-phase C6 cultures were exposed to dexamethasone (day 0), cell densities were not significantly different from controls by day 1. Cell proliferation ceased thereafter in dexamethasone-treated cultures, whereas control cell populations continued to proliferate at log-phaserates. In contrast, cellular DNA increased exponentially in control and treated cultures over the 3-day period. On days 0 and 1, control and treated cells each contained 6 pg DNA. By day 3, the DNA content per treated cell increased to >20 pg; control cells each contained 10 pg DNA. The rates of DNA synthesis in the treated cultures did not differ significantly from controls on days 1 and 2. However, the rate in the treated cultures decreased significantly on day 3, one day after cell proliferation ceased. On day 2, the percentage of cells found in metaphase in the treated cultures was 0.32% compared to 0.64% in control cultures. By day 3, these percentages decreased to 0.20% and 0.22%, respectively. However, the proportion of metaphases containing >42 chromosomes increased 1.5-fold in the treated cultures relative to controls. These results indicate that nonproliferating dexamethasone-treated cells contain elevated amounts of DNA. Thus dexamethasone action appears to arrest the cell cycle at any point between the completion of DNA replication and mitosis. A preliminary report of this work was presented on June 8, 1977, at the 28th Annual Meeting of the Tissue Culture Association in New Orleans, Louisiana. This investigation was supported in part by grants from Merck Sharp & Dohme Research Laboratories, West Point, Pa., the American Cancer Society (IN-113), and NIH (AM 18719).     

Male nest site fidelity and female serial polyandry in lingcod (Ophiodon elongatus, Hexagrammidae)

Nest site fidelity and serial polyandry were examined in lingcod, Ophiodon elongatus, a teleost fish in which the nest-guarding male parent invests more heavily in parental care than the elusive female parent. Lingcod parental and progeny genotypes were established for fish spawning on a 200 m(2) section of Snake Island reef, British Columbia in two successive years to evaluate male and female mate choice (monogamy or polygamy) and nest site reuse by the same parents (nest site fidelity) and/or different parents (nest site affinity). Thirteen nests (egg masses) guarded by nine males and 14 nests guarded by seven males were observed in 2002 and 2003, respectively. No female laid more than one nest per season or spawned in the study area in both years. In contrast, at least six (86%) and possibly all seven (100%) of the 2003 guardian males had been guardian or auxiliary males in 2002. Both nest site affinity and extreme male nest site fidelity were observed, with at least four males reusing the exact same nest site. Serial polyandry resulting from the high male and low female nest site fidelity is consistent with predictions based on a low female parental investment and high rate of progeny loss to predation and cannibalism. Male polygyny, achieved primarily by cuckoldry within seasons, was enhanced by the lack of female fidelity between seasons. Polygamy in both sexes of nest-tending marine fish may minimize reproductive skew and maximize genetic diversity within populations.     

In vitro cortical neuronal networks as a new high-sensitive system for biosensing applications

By taking advantages of the main features of the microelectrode array (MEA) technology (i.e. multisite recordings, stable and long-term coupling with the biological preparation), we analyzed the changes in activity patterns induced by applying specific substances to dissociated cortical neurons from rat-embryos (E18). Data were recorded simultaneously from 60 electrodes, and the electrophysiological behavior was investigated during the third week in vitro, both at the spike and burst level. The analysis of the electrophysiological activity modulation, by applying agonists of the ionotropic glutamate receptors at low (i.e. 0.2-1-5 microM) and high (i.e. 50-100 microM) concentrations, is presented. Preliminary results show that the dynamics of the in vitro cortical neurons is very sensitive to pharmacological manipulation of the glutamatergic transmission and the effects on the network behavior are strictly dependent from the drug concentration. In particular, the addition of a high-dose of agonist determined a global and irreversible depression of the network activity, while, in the low-concentration case, the electrophysiological behavior showed different results, depending on the type of receptor involved. From these observations, we are encouraged to think of a more engineered system, based on in vitro cortical neurons, as a novel sensitive system for drug (pre)-screening and neuropharmacological evaluations.     

Hepatitis C virus drives the unconstrained monoclonal expansion of VH1-69-expressing memory B cells in type II cryoglobulinemia: a model of infection-driven lymphomagenesis

Chronic hepatitis C virus infection causes B cell lymphoproliferative disorders that include type II mixed cryoglobulinemia and lymphoma. This virus drives the monoclonal expansion and, occasionally, the malignant transformation of B cells producing a polyreactive natural Ab commonly encoded by the V(H)1-69 variable gene. Owing to their property of producing natural Ab, these cells are reminiscent of murine B-1 and marginal zone B cells. We used anti-Id Abs to track the stages of differentiation and clonal expansion of V(H)1-69(+) cells in patients with type II mixed cryoglobulinemia. By immunophenotyping and cell size analysis, we could define three discrete stages of differentiation of V(H)1-69(+) B cells: naive (small, IgM(high)IgD(high)CD38(+)CD27(-)CD21(high)CD95(-)CD5(-)), "early memory" (medium-sized, IgM(high)IgD(low)CD38(-)CD27(+)CD21(low)CD95(+)CD5(+)), and "late memory" (large-sized, IgM(low)IgD(low-neg)CD38(-)CD27(low)CD21(low-neg)CD5(-)CD95(-)). The B cells expanded in cryoglobulinemia patients have a "memory" phenotype; this fact, together with the evidence for intraclonal variation, suggests that antigenic stimulation by hepatitis C virus causes the unconstrained expansion of activated V(H)1-69(+) B cells. In some cases, these cells replace the entire pool of circulating B cells, although the absolute B cell number remains within normal limits. Absolute monoclonal V(H)1-69(+) B lymphocytosis was seen in three patients with cryoglobulinemia and splenic lymphoma; in two of these patients, expanded cells carried trisomy 3q. The data presented here indicate that the hepatitis C virus-driven clonal expansion of memory B cells producing a V(H)1-69(+) natural Ab escapes control mechanisms and subverts B cell homeostasis. Genetic alterations may provide a further growth advantage leading to an overt lymphoproliferative disorder.     

Multinuclear (P, Pt) magnetic resonance and electrospray mass spectrometric studies of the reactions between platinum bis(dithiolates) and two potentially tetradentate phosphine ligands

The reactions of platinum(II) bis(dithiolates) Pt(S---S)₂ ((S---S)=S₂P(OEt)₂ (dtp), S₂COⁿPr (xan), S₂CNEt₂ (dtc)) with two potentially tetradentate phosphine ligands have been investigated by multinuclear magnetic resonance spectroscopy and electrospray mass spectrometry (ESMS). The phosphines used were P(CH₂CH₂PPh₂)₃ (P₃P′) and Ph₂PCH₂CH₂P(Ph)CH₂CH₂P(Ph)CH₂CH₂PPh₂ (P₂P′₂). ³¹P and ¹⁹⁵Pt NMR spectroscopies show that P₃P′ reacts in dichloromethane solution with Pt(dtp)₂ and Pt(xan)₂ to give five-coordinate [(η⁴-P₃P′)Pt(η¹-S---S)]⁺ and with Pt(dtc)₂ to give a temperature dependent mixture of [(η⁴-P₃P′)Pt(η¹-dtc)]⁺ and [(η³-P₃P′)Pt(η²-dtc)]⁺. All these formulations were confirmed by observation of the intact ions in the ES mass spectra directly from the solutions. [(η⁴-P₃P′)Pt(η¹-xan)]⁺ slowly reacts with the free xan ion to give the dithiocarbonate complex (η³-P₃P′)Pt(η²-S₂CO). The pendant phosphine in [(η³-P₃P′)Pt(η²-dtc)]⁺ undergoes various chemical reactions such as methylation and reaction with sulfur, and the cation behaves as a monodentate phosphine towards Pt(dtp)₂ to give [(η¹-dtp)(η²-dtp)Pt(η¹-μ²-η³-P₃P′)Pt(η²-dtc)]⁺ which was fully characterised by multi-NMR spectroscopy and confirmed by observation of the intact ion by ESMS. P₂P′₂ reacts with Pt(dtp)₂ to give [(P₂P′₂)Pt]²⁺, but with Pt(xan)₂ and Pt(dtc)₂ the products are [(η⁴-P₂P′₂)Pt(η¹-S---S)]⁺, but the xanthate complex slowly de-alkylates to give (η³-P₂P′₂)Pt(η²-S₂CO). The identities of the cationic P₂P′₂ species in solution were confirmed by direct observation of the intact ion by ESMS.