Gastrointestinal microflora,food components and colon cancer prevention

Evidence that the intestinal microbiota is intrinsically linked with overall health, including cancer risk, is emerging. Moreover, its composition is not fixed but can be influenced by several dietary components. Dietary modifiers, including the consumption of live bacteria (probiotics) and indigestible or limited digestible food constituents such as oligosaccharides (prebiotics) and polyphenols or both (synbiotics), are recognized modifiers of the numbers and types of microbes and have been reported to reduce colon cancer risk experimentally. Microorganisms also have the ability to generate bioactive compounds from food components. Examples include equol from isoflavones, enterodiol and enterolactone from lignans and urolithins from ellagic acid, which have also been demonstrated to retard experimentally induced cancers. The gastrointestinal microbiota can also influence both sides of the energy balance equation, namely, as a factor influencing energy utilization from the diet and as a factor that influences host genes that regulate energy expenditure and storage. Because of the link between obesity and cancer incidence and mortality, this complex complexion deserves greater attention. Overall, a dynamic interrelationship exists between the intestinal microbiota and colon cancer risk, which can be modified by dietary components and eating behaviors.     

Floral colour diversity in plant communities,bee colour space and a null model

Evolutionary biologists have long hypothesized that the diversity of flower colours we see is in part a strategy to promote memorization by pollinators, pollinator constancy, and therefore, a directed and efficient pollen transfer between plants. However, this hypothesis has never been tested against a biologically realistic null model, nor were colours assessed in the way pollinators see them. Our intent here is to fill these gaps. Throughout one year, we sampled floral species compositions at five ecologically distinct sites near Berlin, Germany. Bee-subjective colours were quantified for all 168 species. A model of colour vision was used to predict how similar the colours of sympatric and simultaneously blooming flowers were for bees. We then compared flower colour differences in the real habitats with those of random plant communities. We did not find pronounced deviations from chance when we considered common plants. When we examined rare plants, however, we found significant divergence in two of the five plant communities. At one site, similarly coloured species were found to be more frequent than expected, and at the other two locations, flower colours were indistinguishable from a random distribution. These results fit theoretical considerations that rare plants are under stronger selective pressure to secure pollination than common plants. Our study illustrates the power of linking such distinct biological traditions as community ecology and the neuroethology of bee vision.     

Purification and isolation of the arom aggregates of Schizosaccharomyces pombe

The five enzymes that catalyzing steps two through six in the prechorismate polyaromatic amino acid biosynthetic pathway are physically associated and have been purified up to 400-fold from Schizosaccharomyces pombe. The native arom aggregate has a molecular weight of approx. 140,000-145,000 based on gel filtration, glycerol-density-gradient centrifugation, and polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. Similarities between the S. pombe arom aggregate and that of Neurospora crassa and Euglena gracilis are discussed.     

Genome Sequence and Comparative Genomics Analysis of a Vibrio cholerae O1 Strain Isolated from a Cholera Patient in Malaysia

The genome sequence analysis of a clinical Vibrio cholerae VC35 strain from an outbreak case in Malaysia indicates multiple genes involved in host adaptation and a novel Na⁺-driven multidrug efflux pump-coding gene in the genome of Vibrio cholerae with the highest similarity to VMA_001754 of Vibrio mimicus VMA223.     

Species pattern of phosphatidylinositol from lung surfactant and a comparison of the species pattern of phosphatidylinositol and phosphatidylglycerol synthesized de novo in lung microsomal fractions.

1. Phosphatidylinositol (PI) is a minor component of lung surfactant which may be able to replace the functionally important phosphatidylglycerol (PG) [Beppu, Clements & Goerke (1983) J. Appl. Physiol. 55, 496-502] without disturbing lung function. The dipalmitoyl species is one of the main species for both PI (14.4%) and PG (16.9%). Besides the C16:0--C16:0 species, the C16:0--C18:0, C16:0--C18:1, C16:0--C18:2 and C18:0--C18:1 species showed comparable proportions in the PG and PI fractions. These similarities of the species patterns and the acidic character of both phospholipids could explain why surfactant PG may be replaced by PI. 2. PI and PG were radiolabelled by incubation of microsomal fractions with [14C]glycerol 3-phosphate (Gro3P). For 11 out of 14 molecular species of PI and PG we measured comparable proportions of radioactivity. The radioactivity of these 11 species accounted together for more than 80% of the total. The addition of inositol to the incubation system decreased the incorporation in vitro of Gro3P into PG and CDP-DG (diacylglycerol) of lung microsomes (microsomal fractions), but did not change the distribution of radioactivity among the molecular species of PG. These results supported the idea that both acidic surfactant phospholipids may be synthesized de novo from a common CDP-DG pool in lung microsomes.     

The core region of human glutaminyl-tRNA synthetase homologies with the Escherichia coli and yeast enzymes.

We have isolated from a Lambda-gt 11 library a human cDNA clone with one open reading frame of about 2400 bases. A stretch of about 350 amino acids in the deduced amino acid sequence is up to 40 percent identical with parts of the known amino acid sequences of E. coli and yeast glutaminyl (Gln)-tRNA synthetase. The isolated cDNA sequence corresponds to an internal section of a 5500 bases long mRNA that codes for a 170 kDa polypeptide associated with Gln-tRNA synthetase. Thus, the human enzyme is about three times larger than the E. coli and two times larger than the yeast Gln-tRNA synthetase. The three enzymes share an evolutionarily conserved core but differ in amino acid sequences linked to the N-terminal and C-terminal side of the core.     

Improved procedure for the purification of hepatic lipase from rat liver homogenate

A procedure is described for the purification of hepatic lipase (HL)4 from rat liver homogenate which results in a high yield (41%) of electrophoretically homogeneous enzyme. The method is based on that of Twu et al. (Biochim. Biophys. Acta 1984: 792, 330), but it is more efficient with respect to yield (about 4-fold) and purity (1.6-fold). It includes the preparation of a high-speed supernatant, chromatography in series on octyl-, heparin- and concanavalin A-Sepharose, and finally gel filtration. On SDS-PAGE analysis, the purified enzyme exhibited an apparent molecular mass of 63.6 +/- 3.2 kDa. Heterogeneity was observed, when purified HL was subjected to isoelectric focussing. The enzyme displayed a specific catalytic activity of 23,000 U* (mumol fatty acid released per h at 37 degrees C) per mg protein, when assayed with trioleoyl glycerol suspensions in arabic gum. A highly specific antiserum against rat liver HL, capable of inhibiting 817 mU* HL per microliter antiserum, was raised in rabbits.