Effects of cyanobacterium exopolysaccharides on life-history of Ceriodaphnia cornuta SARS

The objective of the present investigation was to verify ifAnabaena spiroides exopolysaccharides sustains growth and reproductionof Ceriodaphnia cornuta. The animals were raised in controlledlaboratory conditions and fed exclusively on A. spiroides exopolysaccharides,which were obtained from filtered stationary growth phase A.spiroides cultures. A molecular weight cut-off of 12–14kDa was used to separate the exopolysaccharides from low molecularweight materials. The lyophilized exopolysaccharides were dissolvedin filtered and autoclaved reservoir water at a concentrationof 15 mg L^–1 (0.22 ± 0.01 mg C animal^–1day^–1).These results were compared with animals fed on seston at naturalconcentration obtained by filtering (68 µm) Barra BonicaReservoir water (0.23 ± 0.01 mg C animal^–1day^–1).Several life history parameters (duration of embryonic development,generation time, reproductive performance, age-specific length,primipara age and length) were obtained during 15-day experiments.Growth rate (GR) and weight-specific secondary production werealso quantified. Exopolysaccharide-fed organisms had bettergrowth and reproductive performance (0.091 ± 0.004 GR;51 ± 4.59 eggs produced per female) than seston-fed individuals(0.078 ± 0.010 GR; 30.90 ± 7.25 eggs producedper female). These results show that such macromolecules area potential food source, fulfilling nutritional requirementsto sustain growth and reproduction of C. cornuta and supportstrophic relationships in aquatic ecosystems.     

Magnesia-zirconia based mimetic biomembrane chromatography for predicting human drug absorption

In this paper, a novel mimetic biomembrane chromatography stationary phase of magnesia-zirconia composite matrix were prepared with the Lewis acid-base interaction between phosphatidylcholine's residue phosphonate group and Lewis acid sites of magnesia-zirconia composite; the retention factors of a chemically diverse set of drugs on the new stationary phase were determined; the drugs logK(mbm) values were correlationed with the absorbed fraction of drugs orally administered in humans (%F(a)) and a hyperbolic relationship was obtained. Meanwhile, the relationship between the logK(mbm) values and hydrophobic parameters (logP(oct) and logD(oct)) were discussed. The usefulness of the new column for predicting oral drug absorption in humans is demonstrated by comparing this model with IAM, ILC and BMC models. Results show that the logK(mbm) values have good relationship with logK(W)(IAM), logK(BMC) and have moderate to fair relationship with logK(s) determined on four different ILC column (EPL, PC, PC-PE, PC-PS). Therefore, the logK(mbm) values can provide key information about the transport properties of drugs and this chromatographic model may be applicable for prediction of drug uptake through epithelial cell membranes during the drug discovery process.     

Altered gene expression profiles of NIH3T3 cells regulated by human lung cancer associated gene CT120

CT120, a novel membrane-associated gene implicated in lung carcinogenesis, was previously identified from chromosome 17pl 3.3 locus, a hot mutation spot involved in human malignancies. In the present study, we further determined that CT120 ectopic expression could promote cell proliferation activity of NIH3T3 cells using MTS assay, and monitored the downstream effects of CT120 in NIH3T3 cells with Atlas mouse cDNA expression arrays. Among 588 known genes, 133 genes were found to be upregulated or downregulated by CT120. Two major signaling pathways involved in cell proliferation, cell survival and anti-apoptosis were overexpressed and activated in response to CT120:One is the Raf/MEK/Erk signal cascades and the other is the PI3K/Akt signal cascades, suggesting that CT120 might contribute, at least in part, to the constitutively activation of Erk and Akt in human lung caner cells. In addition, some tumor metastasis associated genes cathepsin B, cathepsin D, cathepsin L, MMP-2/TIMP-2 were also upregulated by CT120, upon which CT120 might be involved in tumor invasiveness and metastasis. In addition, CT120 might play an important role in tumor progression through modulating the expression of some candidate “Lung Tumor Progression”genes including B-Raf, Rab-2, BAX, BAG-1, YB-1, and Cdc42.     

LIGHT sensitizes IFNγ-mediated apoptosis of HT-29 human carcinoma cells through both death receptor and mitochondria pathways

LIGHT [homologous to lymphotoxins, shows inducible expression, and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator (HVEM/TR2)] is a new member of TNF superfamily. The HT-29 colon cancer cell line is the most sensitive to LIGHT-induced, IFNγ-mediated apoptosis among the cell lines we have examined so far. Besides downregulation of Bcl-XL, upregulation of Bak, and activation of both PARP [poly (ADP-ribose) polymerase] and DFF45 (DNA fragmentation factor), LIGHT-induced, IFNy-mediated apoptosis of HT-29 cells involves extensive caspase activation. Caspase-8 and caspase-9 activation, as shown by their cleavages appeared as early as 24 h after treatment, whereas caspase-3 and caspase-7 activation, as shown by their cleavages occurred after 72h of LIGHT treatment. Caspase-3 inhibitor Z-DEVD-FMK (benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone) and a broad range caspase inhibitor Z-VAD-FMK (benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone) were able to block LIGHT-induced, IFNγ-mediated apoptosis of HT-29 cells. The activity of caspase-3, which is one of the major executioner caspases, was found to be inhibited by both Z-DEVD-MFK and Z-VAD-FMK. These results suggest that LIGHT-induced, IFNy-mediated apoptosis of HT-29 cells is caspase-dependent, and LIGHT signaling is mediated through both death receptor and mitochondria pathways.     

Increasing pre-term and low-birth-weight rates over time and their impact on infant mortality in south-east Brazil

This study investigates the possible effects of pre-term births and low birth weight on infant mortality rates (IMRs) over a 15-year period in Ribeir?o Preto, Brazil, based on surveys carried out in 1978/79 and 1994. The 1978/79 survey included 6750 births over a 12-month period and the 1994 survey 2846 births over a 4-month period. Infant deaths were retrieved monthly from the city register. Infant mortality rate decreased from 36.6 to 16.9 deaths per 1000 over 15 years. The decrease in IMR was larger in the 2500-2999 g group than in any other group. The observed falls in IMR were attributable to decreases in birth-weight-specific mortality rates. Likewise, there was a general decrease in IMR in mild, moderate and severe pre-term births. The incidence rate ratio of infant mortality between surveys was 0.46 (95% CI 0.34-0.63); it increased to 0.57 (95% CI 0.35-0.75) when adjusted for birth weight and other factors in the model and rose to 0.69 (95% CI 0.49-0.97) when adjusted for length of gestation and other variables. The increase in pre-term births and low birth weight may have had, at most, a marginal effect on the IMR. Progress in the care of newborns may have decreased the mortality risk, but even mild pre-term birth still has an impact on infant mortality. There is room for further improvement in IMR by tackling the high rates of pre-term birth.     

Gibberellin regulates Arabidopsis floral development via suppression of DELLA protein function

The phytohormone gibberellin (GA) regulates the development and fertility of Arabidopsis flowers. The mature flowers of GA-deficient mutant plants typically exhibit reduced elongation growth of petals and stamens. In addition, GA-deficiency blocks anther development, resulting in male sterility. Previous analyses have shown that GA promotes the elongation of plant organs by opposing the function of the DELLA proteins, a family of nuclear growth repressors. However, it was not clear that the DELLA proteins are involved in the GA-regulation of stamen and anther development. We show that GA regulates cell elongation rather than cell division during Arabidopsis stamen filament elongation. In addition, GA regulates the cellular developmental pathway of anthers leading from microspore to mature pollen grain. Genetic analysis shows that the Arabidopsis DELLA proteins RGA and RGL2 jointly repress petal, stamen and anther development in GA-deficient plants, and that this function is enhanced by RGL1 activity. GA thus promotes Arabidopsis petal, stamen and anther development by opposing the function of the DELLA proteins RGA, RGL1 and RGL2.     

A novel method for measuring photosynthesis using delayed fluorescence of chloroplast

Photosynthesis is the most important chemical reaction in the world. The measurement of plant photosynthesis rate plays an important role in agriculture. Light-induced delayed fluorescence (DF) in plants is an intrinsic label of the efficiency of charge separation at P680 in photosystem II (PS II). In this paper, we have developed a biosensor that can accurately measure the plant photosynthesis ability by means of DF. Compared with common methods for measuring the photosynthesis rate based on consumption of CO2, the proposed technique can quantify the plant photosynthesis ability with less influence of the environment. The biosensor is an all-weather measuring instrument, it has its own illumination power and utilizes intrinsic DF as the measurement marker. The current investigation has revealed that, there is a good correspondence between the results measured by the biosensor and that by commercially available portable photosynthesis system under controlled conditions. We thus conclude that DF is an excellent marker for evaluating plant photosynthesis ability under its biological status with less interferences of the environment.     

Lipophilic triphenylphosphonium cations as tools in mitochondrial bioenergetics and free radical biology

Lipophilic phosphonium cations were first used to investigate mitochondrial biology by Vladimir Skulachev and colleagues in the late 1960s. Since then, these molecules have become important tools for exploring mitochondrial bioenergetics and free radical biology. Here we review why these molecules are useful in mitochondrial research and outline some of the ways in which they are now being utilized.Translated from Biokhimiya, Vol. 70, No. 2, 2005, pp. 273–283.Original Russian Text Copyright ¢ 2005 by Ross, Kelso, Blaikie, James, Cochemé, Filipovska, Da Ros, Hurd, Smith, Murphy.This revised version was published online in April 2005 with corrections to the post codes.     

The pseudo-immunoreceptor tyrosine-based activation motif of CD5 mediates its inhibitory action on B-cell receptor signaling

Genetic studies revealed that CD5 could be a negative regulator of the B-cell antigen receptor (BCR). We explore here the effect of human CD5 on BCR-triggered responses. B cells were obtained expressing a chimera composed of extracellular and transmembrane domains of Fcgamma type IIB receptor fused to CD5 cytoplasmic domain (CD5cyt). Coligation of the chimera with the BCR induces CD5cyt tyrosine phosphorylation. A rapid inhibition of BCR-induced calcium response is observed, as well as a partial but delayed inhibition of phospholipase Cgamma-1 phosphorylation. Activation of extracellular regulated kinase-2 is also severely impaired. Moreover, at the functional level, interleukin-2 production is abolished. Src homology 2 domain-bearing tyrosine phosphatase SHP-1 and Src homology 2 domain-bearing inositol 5'-phosphatase SHIP usually participate in negative regulation of the BCR. We show that they do not associate with the phosphorylated CD5 chimera. We finally demonstrate that the pseudo-immunoreceptor tyrosine based activation motif present in CD5cyt is involved because its deletion eliminates the inhibitory effect of the chimera, both at biochemical and functional levels. These results demonstrate the inhibitory role of CD5 pseudo-immunoreceptor tyrosine based activation motif tyrosine phosphorylation on BCR signaling. They further support the idea that CD5 uses mechanisms different from those already described to negatively regulate the BCR pathway.