Diversity and technological properties of predominant lactic acid bacteria from fermented cassava used for the preparation of Gari, a traditional African food

Traditional fermentation of cassava is dominated by a lactic acid bacteria (LAB) population. Fermentation is important for improving product flavour and aroma as well as safety, especially by reduction of its toxic cyanogenic glucosides. The production of Gari from cassava in Benin typically occurs on a household or small industrial scale, and consequently suffers from inconsistent product quality and may not always be safe for consumption. Therefore, the diversity of LAB from a typical cassava fermentation for the preparation of Gari, and their technologically relevant characteristics were investigated with a view towards selection of appropriate starter cultures. A total of 139 predominant strains isolated from fermenting cassava were identified using phenotypic tests and genotypic methods such as rep-PCR and RAPD-PCR. DNA-DNA hybridisation and sequencing of the 16S rRNA genes were done for selected strains. Lactobacillus plantarum was the most abundantly isolated species (54.6% of isolates), followed by Leuconostoc fallax (22.3%) and Lactobacillus fermentum (18.0%). Lactobacillus brevis, Leuconostoc pseudomesenteroides and Weissella paramesenteroides were sporadically isolated. The L. plantarum strains were shown to be better acid producers and capable of faster acid production than the L. fallax or L. fermentum strains. The incidence of beta-glucosidase (linamarase) activity was also highest among strains of this species. Production of antagonistic substances such as H2O2 and bacteriocins, however, was more common among L. fallax and L. fermentum strains. Strains of all three species were capable of utilising the indigestible sugars raffinose and stachyose. Therefore, a starter culture containing a mixture of strains from all three species was recommended.     

Influence of UV-B Supplemental Radiation on Growth and Pigment Content in Suaeda Maritima L.

In a field experiment with a mangrove species Suaeda maritima L. grown under ambient and supplementary UV-B radiation corresponding to 20 % ozone depletion, changes in growth and contents of photosynthetic and UV-absorbing pigments were determined. Supplemental UV-B irradiation for 9 d significantly reduced the growth and concentration of photosynthetic pigments. However, anthocyanin and flavonoid contents were significantly increased in UV-treated plants and which could be reduce the UV-B penetration and damage to the underlying tissues.     

Immunoreactive hephaestin and ferroxidase activity are present in the cytosolic fraction of rat enterocytes

Discovered over a decade ago, hephaestin (Heph) has been implicated as a ferroxidase (FOX) vital for intestinal iron absorption. Stringent structural or kinetic data derived from purified, native protein is however lacking, leading to the hypothesis that an alternate, undiscovered form of Heph could exist in mammalian enterocytes. This possibility was tested using laboratory rodent and cell culture models. Cytosolic and membrane fractions were obtained from rat enterocytes and purity of the fractions was assessed. Western blot analyses revealed Heph in cytosol obtained by three different methods, ruling out the possibility of a method-induced artifact being the major contributor to this observation. Absence of two different membrane-proteins, ferroportin 1 and Menke's copper ATPase in cytosol, and the absence of lipids in representative cytosolic samples tested by thin layer chromatography, eliminated significant membrane contamination of cytosol. Further, immunohisto- and immunocyto-chemical analyses identified Heph in rat enterocytes and in two intestinal epithelial cell lines, IEC-6 and Caco-2, intracellularly. Additionally, cytosolic Heph increased upon iron-deprivation but more important, decreased significantly upon copper-deprivation, mimicking the response of membrane-bound Heph. Moreover, FOX activity was present in rat cytosol, and was partly inhibited by anti-Heph antibody. Finally, lack of immunodetectable ceruloplasmin (Cp) by western blot precluded Cp as an underlying cause of this activity. These data demonstrate that rat enterocytes contain a soluble/cytosolic form of Heph possibly contributing to the observed FOX activity.     

Design and synthesis of AB(3)-type (A = 1,3,5-benzenetricarbonyl unit; B = Glu diOME or Glu(7) octa OMe) peptide dendrimers: crystal structure of the first generation

The first generation molecule of glutamic acid-based dendrons on a 1, 3,5-benzenetricarbonyl core leads to a cylindrical assembly as demonstrated by single crystal x-ray diffraction. The benzene pi-pi stack (A) is stabilized by vertical NH...O===C hydrogen bonding with each subunit participating in three intermolecular hydrogen bonds related by three-fold rotation symmetry.     

C. elegans locomotory rate is modulated by the environment through a dopaminergic pathway and by experience through a serotonergic pathway

Caenorhabditis elegans modulates its locomotory rate in response to its food, bacteria, in two ways. First, well-fed wild-type animals move more slowly in the presence of bacteria than in the absence of bacteria. This basal slowing response is mediated by a dopamine-containing neural circuit that senses a mechanical attribute of bacteria and may be an adaptive mechanism that increases the amount of time animals spend in the presence of food. Second, food-deprived wild-type animals, when transferred to bacteria, display a dramatically enhanced slowing response that ensures that the animals do not leave their newly encountered source of food. This experience-dependent response is mediated by serotonergic neurotransmission and is potentiated by fluoxetine (Prozac). The basal and enhanced slowing responses are distinct and separable neuromodulatory components of a genetically tractable paradigm of behavioral plasticity.     

Studies on the effect of storage of normolipidemic plasma on the metabolism of very-low-density lipoprotein cholesterol in human skin fibroblasts

Very-low-density lipoproteins (VLDL) isolated from fresh normolipidemic plasma were able to compete with labeled low-density lipoproteins (LDL) for receptor binding as efficiently as LDL in human skin fibroblasts. However, VLDL from fresh plasma failed to stimulate acyl-CoA: cholesterol acyltransferase (ACAT) (EC 2.3.1.26) activity significantly. When plasma was stored at 4 degrees C for 24-48 h before ultracentrifugation, the VLDL were able to stimulate ACAT activity significantly. Proteolytic and lipolytic enzymes do not appear to play a role in this phenomenon. The increased capacity of VLDL from stored plasma to stimulate ACAT activity appears to be due partly to the increase in the internalization and degradation processes. Both the larger and the smaller VLDL subclasses were able to stimulate ACAT activity in the cells. The actual changes that take place in the VLDL molecule during the storage of plasma are not known.