Microbiological quality of wheat flour consumed in Morocco

Cereal products (soft and hard wheat) are a basic staple food in the Moroccan diet. A total of 60 samples of two types of wheat flours used for human consumption were collected; 30 samples among this collection were obtained from various households using Moroccan varieties of wheat produced in traditional flour mills. The rest of the samples were purchased from retail wheat flour sources in the Rabat and Sale city markets. Standard plate counts (SPC), total and faecal coliforms, Clostridium, Salmonella spp., Shigella spp., Staphylococcus aureus, Listeria monocytogenes, yeast, lactic acid bacteria, and molds, were carried out to assess the microbiological quality of wheat flour. Microbiological interpretation of the criteria was performed according to standards implemented by the Codex Alimentarius Commission. Most frequent counts, in traditional and industrial wheat flour, were total aerobic mesophilic bacteria with an average 4 × 104 and 2.5 × 104 cfu/g, respectively. The results showed higher coliform and fungi counts in house than in commercial samples. Pathogenic flora as Salmonella spp., Shigella spp., S. aureus, L. monocytogenes, and Clostridium were not detected in all investigated samples. Bacterial strains isolated from both flours belong to the following genera: Enterobacter spp., Serratia spp., Klebsiella spp., Pantoea spp., Leclercia spp., Proteus spp. The most frequent genus of the investigated isolates was Aspergillus (81 %). Microbial counts were lower than the limit laid down in the Codex Alimentarius, attributing to these flours a satisfactory microbiological quality.     

A novel, generic and effective method for the rapid purification of G protein-coupled receptors

G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are of major therapeutic importance. Structure determination of G protein-coupled receptors and other applications require milligram quantities of purified receptor proteins on a regular basis. Recombinant GPCRs fused to a heterologous biotinylation domain were produced in the yeast Pichia pastoris. We describe an efficient method for their rapid purification that relies on the capture of these receptors with streptavidin immobilized on agarose beads, and their subsequent release by enzymatic digestion with TEV protease. This method has been applied to several GPCRs belonging to the class A rhodopsin subfamily, leading to high yields of purified proteins; it represents a method of choice for biochemical and biophysical studies when large quantities of purified GPCRs are needed.     

Plant intelligence: Why,why not or where?

The concept of plant intelligence, as proposed by Anthony Trewavas, has raised considerable discussion. However, plant intelligence remains loosely defined; often it is either perceived as practically synonymous to Darwinian fitness, or reduced to a mere decorative metaphor. A more strict view can be taken, emphasizing necessary prerequisites such as memory and learning, which requires clarifying the definition of memory itself. To qualify as memories, traces of past events have to be not only stored, but also actively accessed. We propose a criterion for eliminating false candidates of possible plant intelligence phenomena in this stricter sense: an “intelligent” behavior must involve a component that can be approximated by a plausible algorithmic model involving recourse to stored information about past states of the individual or its environment. Re-evaluation of previously presented examples of plant intelligence shows that only some of them pass our test.

“You were hurt?” Kumiko said, looking at the scar.Sally looked down. “Yeah.”“Why didn''t you have it removed?”“Sometimes it''s good to remember.”“Being hurt?”“Being stupid.”—(W. Gibson: Mona Lisa Overdrive)

Key words: intelligence, memory, learning, plant development, mathematical models, plant neurobiology, definition of terms     

Integrated immobilized cell reactor-adsorption system for β-cyclodextrin production: a model study using PVA-cryogel entrapped Bacillus agaradhaerens cells

Production of cyclodextrins (CDs) by immobilized cells of the alkaliphilic Bacillus agaradhaerens LS-3C with integrated product recovery was studied. The microorganism was entrapped in polyvinyl alcohol-cryogel beads and used as a convenient source of immobilized cyclodextrin glycosyltransferase (CGTase). On activation by incubation in the cultivation medium containing 1% (w/v) starch, the entrapped cells multiplied and secreted CGTase with an activity of 2–3 mg -cyclodextrin h^–1 g^–1 beads. The immobilized biocatalyst exhibited maximum activity at pH 9 and 50 °C, and formed cyclodextrins comprising 92–94% -CD and remaining -CD. The cyclodextrin product from the immobilized cell bioreactor was continuously recovered by adsorption to Amberlite XAD-4 in a recycle batch mode. The product adsorption was facilitated at low temperature while hot water was used for elution.     

Polymeric cryogels as promising materials of biotechnological interest

Cryogels are gel matrices that are formed in moderately frozen solutions of monomeric or polymeric precursors. Cryogels typically have interconnected macropores (or supermacropores), allowing unhindered diffusion of solutes of practically any size, as well as mass transport of nano- and even microparticles. The unique structure of cryogels, in combination with their osmotic, chemical and mechanical stability, makes them attractive matrices for chromatography of biological nanoparticles (plasmids, viruses, cell organelles) and even whole cells. Polymeric cryogels are efficient carriers for the immobilization of biomolecules and cells.     

Assessment of multidrug resistance reversal using dielectrophoresis and flow cytometry

In cancer, multidrug resistance (MDR) is the simultaneous resistance of tumor cells to different natural product anticancer drugs that have no common structure. This is an impediment to the successful treatment of many human cancers. A common correlate of MDR is the overexpression of a membrane protein, P-glycoprotein. Many studies have shown that MDR can be reversed after the use of substrate analogs, called MDR modulators. However, our understanding of MDR modulation is incomplete. In this article, we examine the electrical properties of the human leukemic cells (K562) and its MDR counterpart (K562AR) using dielectrophoresis and flow cytometry (with a membrane potential sensitive dye, DIOC5), both before and after treatment with XR9576 (a P-glycoprotein-specific MDR-reversal agent). The results show significant differences in the cytoplasmic conductivity between the cell lines themselves, but indicate no significant changes after modulation therapy. We conclude that the process of MDR modulation is not associated with changes in the electrical properties of cancer cells. Moreover, the results demonstrate that using the flow cytometry method alone, with MDR cells, may produce artifactual results--whereas in combination with dielectrophoresis, the results show the role of MDR modulators in preventing drug efflux in MDR cells.