Isolation and Partial Characterization of Amaranth and Banana Starches

Alternative sources from different botanical origin were used for starch isolation. Chemical analysis and functional properties were studied in amaranth seed and banana fruit starches. Chemical composition in both starches was different; banana starch presented higher protein, fat and ash levels than that from amaranth. Botanical origin of these starches contributes notably in their chemical composition. Blue value and λmax gave information on starch components: amaranth starch is classified as waxy type and banana starch as normal. Functional properties were evaluated; amaranth starch was more soluble than banana starch, but at higher temperatures amaranth showed lower swelling values than banana starch. The results of freeze-thaw stability suggest that amaranth starch can be used in frozen products. Apparent viscosity studies showed that amaranth starch paste has higher viscosity than banana starch, but the former starch presented higher stability during the 30-min test.     

Calcium Signaling in the Cerebellar Radial Glia and Its Association with Morphological Changes during Zebrafish Development

Radial glial cells are a distinct non-neuronal cell type that, during development, span the entire width of the brain walls of the ventricular system. They play a central role in the origin and placement of neurons, since their processes form structural scaffolds that guide and facilitate neuronal migration. Furthermore, glutamatergic signaling in the radial glia of the adult cerebellum (i.e., Bergmann glia), is crucial for precise motor coordination. Radial glial cells exhibit spontaneous calcium activity and functional coupling spread calcium waves. However, the origin of calcium activity in relation to the ontogeny of cerebellar radial glia has not been widely explored, and many questions remain unanswered regarding the role of radial glia in brain development in health and disease. In this study we used a combination of whole mount immunofluorescence and calcium imaging in transgenic (gfap-GCaMP6s) zebrafish to determine how development of calcium activity is related to morphological changes of the cerebellum. We found that the morphological changes in cerebellar radial glia are quite dynamic; the cells are remarkably larger and more elaborate in their soma size, process length and numbers after 7 days post fertilization. Spontaneous calcium events were scarce during the first 3 days of development and calcium waves appeared on day 5, which is associated with the onset of more complex morphologies of radial glia. Blockage of gap junction coupling inhibited the propagation of calcium waves, but not basal local calcium activity. This work establishes crucial clues in radial glia organization, morphology and calcium signaling during development and provides insight into its role in complex behavioral paradigms.     

Novel desiccants based on designed polymeric blends

We describe a novel concept for the preparation of desiccants based on polymeric blends. A hydrophilic channeling agent (e.g., PEG) is blended with a hydrophobic polymer (e.g., polypropylene) to produce interconnecting hydrophilic channels within the hydrophobic polymer. To make the system desiccating, a water‐absorbing material is blended into the polymeric matrix to become distributed within the hydrophilic portion. The resultant blend may be molded and cast into plug‐type inserts and liners for closed containers, or formed into films, sheets, beads, or pellets; its uses include pharmaceutical and industrial applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 317–327, 2001     

Blue-light induced interaction of LOV domains from Chlamydomonas reinhardtii

The phototropin from Chlamydomonas reinhardtii is a 120 kDa blue light receptor that plays a key role in gametogenesis of this green alga. It comprises two light-sensing domains termed LOV1 and LOV2 (light oxygen and voltage) and a serine/threonine kinase domain. The post-translationally incorporated chromophore is flavin mononucleotide (FMN). Upon absorption of blue light, LOV domains undergo a photocycle that activates a Ser/Thr kinase. The mechanism of this activation is still unknown. We studied the oligomerization of the recombinant LOV1 domain (amino acids 16-133) of C. reinhardtii by means of UV/Vis spectroscopy, size-exclusion chromatography (SEC), and chemical cross-linking with glutardialdehyde. The thermal back-reaction of LOV1 from the signaling state to the dark state as monitored by UV/Vis spectroscopy after an intensive blue light pulse could not be explained by a monoexponential model, although the spectra did not indicate the presence of an additional species. Therefore, we investigated the quaternary structure of the LOV1 domain by size-exclusion chromatography in the dark. This revealed an equilibrium between dimers and higher oligomers (M(W)>200 kDa) under native conditions. No monomers were detected by SEC. However, by analysis of the equilibrium by cross-linking of the protein with glutardialdehyde and subsequent SDS-PAGE, monomers and dimers were identified. Exposure of LOV1 to blue light resulted in a decrease in the monomer/dimer ratio, followed by re-equilibration in the dark. Calculation of the solvent-accessible surface area and the Conolly surfaces of the LOV1 dimers present in the crystal structure support the experimental observation that no mononomers are detected in the native state. A model is presented that accounts for a blue-light-driven change in the quaternary structure of the LOV1 domain and gives hints to the molecular basis of light activation and regulation in LOV-containing proteins.     

Efficient and Chemoselective Surface Immobilization of Proteins by Using Aniline‐Catalyzed Oxime Chemistry

Site‐specific immobilization of peptides and proteins is crucial to ensure their functionality in surface‐based assays. We report the use of aniline‐catalyzed oxime ligations as a very efficient and broadly applicable method to covalently attach the N terminus of proteins and peptides to a surface functionalized with alkoxy‐amine groups.

     

Zur Bildung von Ethoxy-hydrochinazolinon durch Reaktion von Estercarbonylsauerstoff mit Cyan-enamin

Formation of Ethoxyhydroquinazolinone by Attack of an Estercarbonyloxygen at a Cyano Group By the reaction of ethyl-2-oxo-cyclohexanecarboxylate with cyan amide 4-ethoxyhexahydroquinazolin-2-one (12) is formed. Butyl-2-oxo-cyclopentanecarboxylate and cyan amide yield butyl-3-cyanamino-cyclopent-1-en-carboxylate (14) . 2-Oxocyclohexane-carboxamide (1) and ethyl-cyanoacetate form with sodiumhydroxide 4-cyano-octahydroisoquinolin-1, 3-dione (17) and with ammonium acetate ethyl cyclohexylidene-cyanoacetate-2-carboxamide (18) . 18 and ammonia, hydrazine, or cyclohexylamine form the salts of cyanohydroquinazolindione 20a–c , respectively.     

In vitro starch digestibility changes during storage of maize flour tortillas

Nixtamalized maize flours elaborated by four factories in Mexico were used for tortilla preparation. Samples were stored at 4 degrees C for up to 72 h and their in vitro starch digestibility features were evaluated. Moisture content was different between flour and tortilla but no evident relation could be established. Protein and lipid levels were lower in tortillas than in flour but ash content was not different in both samples. A decrease in available starch content was observed upon 48 h cold storage (4 degrees C), changes that were concomitant with increased total resistant starch (RS) levels. These changes were due mainly to retrogradation, as suggested by the increased retrograded resistant starch (RRS) levels recorded in stored tortillas; in some samples, RRS represented up to 100% of total RS. The digestion (alpha-amylolysis) rate (DR) of freshly prepared tortillas differed for the various samples. Although the amylolysis patterns for fresh and 72 h-stored tortillas were similar, lower DR values were shown for the stored materials. The differences found among the various tortilla samples may be due to variations in processing conditions during commercial maize flour preparation, and to the use of different maize varieties.