Evidence for two waves of induction of DNA enzymes in stimulated human lymphocytes

The stimulation of human lymphocytes with phytohaemoagglutinin induces the appearance or increase of several enzymes of DNA metabolism [Pedrini etal., Biochem. Biophys. Res. Comm., 47:1221(1972)]. With long times of stimulation, two phenomena are observed; an increase in the levels of DNA polymerase, of a DNase acting on single-stranded DNA, and of an endonuclease, occurring between the third and fourth day, in parallel with a wave of DNA synthesis;a second wave of increase of the same enzymes and of DNA ligase,occurring between the fifth and eight day when the DNA replication rate, as measured by thymidine-pulses, has decreased to values close to the background.     

Yeasts from Marine and Estuarine Waters with Different Levels of Pollution in the State of Rio de Janeiro, Brazil

Yeast counts were made at 24 marine and estuarine sites in the vicinity of Rio de Janeiro, Brazil. Mean salinities of estuarine sites ranged from 14.2 to 27.4‰, and mean temperatures ranged from 25 to 28°C. Total coliform counts varied from 80% above 100,000 colony-forming units (CFU)/100 ml at heavily polluted sites to 100% below 100 CFU/100 ml at unpolluted sites. Total yeast counts above 100 CFU/100 ml were typical of heavily and moderately polluted water but atypical of lightly polluted and unpolluted water. Mean total yeast counts were 2,880 CFU/100 ml for heavily polluted sites, 202 CFU/100 ml for moderately polluted sites, and 3 CFU/100 ml for lightly polluted and unpolluted sites. Total yeast counts had a positive response to increased pollution levels, and Candida krusei and phenotypically similar yeasts as a group were prevalent in polluted estuarine water but rare in unpolluted seawater. The 549 strains of yeasts and yeast-like organisms isolated were grouped into 67 species, of which the 21 most prevalent made up 86% of the total yeast population. The prevalent genera in the polluted estuary were Candida, Rhodotorula, Torulopsis, Hanseniaspora, Debaryomyces, and Trichosporon.     

Quantification of citrate lyase by enzyme-linked immunosorbent assay for determining the population of Lactococcus lactis subsp. Lactis biovar diacetylactis in pure and mixed cultures

Citrate lyase production by Lactococcus lactis subsp. lactis biovar diacetylactis DRC2 was quantified by an enzyme-linked immunosorbent assay (ELISA). The citrate lyase reached a concentration equivalent to 41 ± 4 g/ml purified citrate lyase in pure culture. When the strain DRC2, grown in mixed culture with L. lactis subsp. cremoris AM2, represented around 70% (DC culture) or 30% (CD culture) of the total initial population, the level of citrate lyase decreased to 21 ± 7 g/ml and 4.5 ± 1.5 g/ml respectively. The maximum bacterial concentration of strain DRC2 in pure culture reached 2.6 × 10⁹ cfu/ml and decreased to 1.5 (± 0.2) × 10⁹ cfu/ml and 0.5 (± 0.3) × 10⁹ cfu/ml in DC and CD mixed cultures respectively. In mixed cultures, the proportion of the strain DRC2 was 8.5 ± 5.0% lower at the end of the fermentation than immediately after inoculation, thus showing that this strain was clearly inhibited. However, the maximum rate of citrate consumption was the same during pure DRC2 culture and CD mixed culture (2.5 ± 0.3 mmol/h) and slightly highre in DC culture (3.07 mmol/h). The maximum rate of acidification was 0.37 ± 0.04 pH unit/h regardless of the culture. A good correlation was obtained between the population of the strain DRC2 and the citrate lyase concentration determined by ELISA but no relationship was found between citrate consumption and citrate lyase synthesis. Therefore an ELISA test of this kind can be used to monitor the growth of L. lactis subsp. lactis biovar diacetylactis in mixed cultures.     

Diversity of ndo genes in mangrove sediments exposed to different sources of polycyclic aromatic hydrocarbon pollution

Polycyclic aromatic hydrocarbon (PAH) pollutants originating from oil spills and wood and fuel combustion are pollutants which are among the major threats to mangrove ecosystems. In this study, the composition and relative abundance in the sediment bacterial communities of naphthalene dioxygenase (ndo) genes which are important for bacterial adaptation to environmental PAH contamination were investigated. Three urban mangrove sites which had characteristic compositions and levels of PAH compounds in the sediments were selected. The diversity and relative abundance of ndo genes in total community DNA were assessed by a newly developed ndo denaturing gradient gel electrophoresis (DGGE) approach and by PCR amplification with primers targeting ndo genes with subsequent Southern blot hybridization analyses. Bacterial populations inhabiting sediments of urban mangroves under the impact of different sources of PAH contamination harbor distinct ndo genotypes. Sequencing of cloned ndo amplicons comigrating with dominant DGGE bands revealed new ndo genotypes. PCR-Southern blot analysis and ndo DGGE showed that the frequently studied nah and phn genotypes were not detected as dominant ndo types in the mangrove sediments. However, ndo genotypes related to nagAc-like genes were detected, but only in oil-contaminated mangrove sediments. The long-term impact of PAH contamination, together with the specific environmental conditions at each site, may have affected the abundance and diversity of ndo genes in sediments of urban mangroves.     

The required role of endogenously produced lipoxin A4 and annexin-1 for the production of IL-10 and inflammatory hyporesponsiveness in mice

The appropriate development of an inflammatory response is central for the ability of a host to deal with any infectious insult. However, excessive, misplaced, or uncontrolled inflammation may lead to acute or chronic diseases. The microbiota plays an important role in the control of inflammatory responsiveness. In this study, we investigated the role of lipoxin A4 and annexin-1 for the IL-10-dependent inflammatory hyporesponsiveness observed in germfree mice. Administration of a 15-epi-lipoxin A4 analog or an annexin-1-derived peptide to conventional mice prevented tissue injury, TNF-alpha production, and lethality after intestinal ischemia/reperfusion. This was associated with enhanced IL-10 production. Lipoxin A4 and annexin-1 failed to prevent reperfusion injury in IL-10-deficient mice. In germfree mice, there was enhanced expression of both lipoxin A4 and annexin-1. Blockade of lipoxin A4 synthesis with a 5-lipoxygenase inhibitor or Abs against annexin-1 partially prevented IL-10 production and this was accompanied by partial reversion of inflammatory hyporesponsiveness in germfree mice. Administration of BOC-1, an antagonist of ALX receptors (at which both lipoxin A4 and annexin-1 act), or simultaneous administration of 5-lipoxygenase inhibitor and anti-annexin-1 Abs, was associated with tissue injury, TNF-alpha production, and lethality similar to that found in conventional mice. Thus, our data demonstrate that inflammatory responsiveness is tightly controlled by the presence of the microbiota and that the innate capacity of germfree mice to produce IL-10 is secondary to their endogenous greater ability to produce lipoxin A4 and annexin-1.     

High-throughput identification of inhibitors of human mitochondrial peptide deformylase

The human mitochondrial peptide deformylase (HsPDF) provides a potential new target for broadly acting antiproliferative agents. To identify novel nonpeptidomimetic and nonhydroxamic acid-based inhibitors of HsPDF, the authors have developed a high-throughput screening (HTS) strategy using a fluorescence polarization (FP)-based binding assay as the primary assay for screening chemical libraries, followed by an enzymatic-based assay to confirm hits, prior to characterization of their antiproliferative activity against established tumor cell lines. The authors present the results and performance of the established strategy tested in a pilot screen of 2880 compounds and the identification of the 1st inhibitors. Two common scaffolds were identified within the hits. Furthermore, cytotoxicity studies revealed that most of the confirmed hits have antiproliferative activity. These findings demonstrate that the designed strategy can identify novel functional inhibitors and provide a powerful alternative to the use of functional assays in HTS and support the hypothesis that HsPDF inhibitors may constitute a new class of antiproliferative agent.     

Mammalian sprouty proteins inhibit cell growth and differentiation by preventing ras activation

Sprouty was genetically identified as an antagonist of fibroblast growth factor signaling during tracheal branching in Drosophila. In this study, we provide a functional characterization of mammalian Sprouty1 and Sprouty2. Sprouty1 and Sprouty2 inhibited events downstream of multiple receptor tyrosine kinases and regulated both cell proliferation and differentiation. Using NIH3T3 cell lines conditionally expressing Sprouty1 or Sprouty2, we found that these proteins specifically inhibit the Ras/Raf/MAP kinase pathway by preventing Ras activation. In contrast, activation of the phosphatidylinositol 3-kinase pathway was not affected by Sprouty1 or Sprouty2. We further showed that Sprouty1 and Sprouty2 do no prevent the formation of a SNT.Grb2.Sos complex upon fibroblast growth factor stimulation, yet block Ras activation. Taken together, these results establish mammalian Sprouty proteins as important negative regulators of growth factor signaling and suggest that Sprouty proteins act downstream of the Grb2.Sos complex to selectively uncouple growth factor signals from Ras activation and the MAP Kinase pathway.     

Does morality have a biological basis? An empirical test of the factors governing moral sentiments relating to incest.

Kin-recognition systems have been hypothesized to exist in humans, and adaptively to regulate altruism and incest avoidance among close genetic kin. This latter function allows the architecture of the kin recognition system to be mapped by quantitatively matching individual variation in opposition to incest to individual variation in developmental parameters, such as family structure and co-residence patterns. Methodological difficulties that appear when subjects are asked to disclose incestuous inclinations can be circumvented by measuring their opposition to incest in third parties, i.e. morality. This method allows a direct test of Westermarck's original hypothesis that childhood co-residence with an opposite-sex individual predicts the strength of moral sentiments regarding third-party sibling incest. Results support Westermarck's hypothesis and the model of kin recognition that it implies. Co-residence duration objectively predicts genetic relatedness, making it a reliable cue to kinship. Co-residence duration predicts the strength of opposition to incest, even after controlling for relatedness and even when co-residing individuals are genetically unrelated. This undercuts kin-recognition models requiring matching to self (through, for example, major histocompatibility complex or phenotypic markers). Subjects' beliefs about relatedness had no effect after controlling for co-residence, indicating that systems regulating kin-relevant behaviours are non-conscious, and calibrated by co-residence, not belief.