Sucrose Ebooks Catalog
The man returned a few minutes later, not with an extra-large-black-no-sugar but rather with coffee grounds, which he rubbed into the cut with brisk, no-nonsense efficiency. Presto the bleeding stopped. Coffee, as it turns out, works as a coagulant. My friends, dumbstruck, thanked these Good
Unlike the other classes of organic compounds already discussed, the sugars and sugar alcohols interact with sodium silicate gradually to form gels over a matter of days. These gels are typically soft, and some sol-gel-sol transformations have been observed. In the cases involving sugar alcohols, the sol-gel-sol transformations could be quite dramatic as these gels were water soluble. Often, a darkening can be observed in the solutions and gels resulting from sugars or sugar alcohols. Any traces of color seemed to be eliminated during the washing process, as the dried gels consist of small whitish chunks.
For subsequent comparative proteomic analyses, an isolation method must allow easy access to relatively large amounts of biological material, typically above 100 mg of proteins. The method should be highly reproducible and relatively quick, so that it can be repeated with ease. To this end, three main strategies have been used magnetic isolation, ultracentrifugation on sucrose gradients and organelle electro-phoresis. The first two mainly make use of synthetic particles, and the last two have been applied to MCVs. Their respective principles, ease of use and quality control issues are discussed here.
The separation of MCVs by ultracentrifugation normally requires two centrifuga-tion steps to achieve sufficient homogeneity. The first step is usually a sucrose gradient and the second a Ficoll or sucrose cushion. Such procedures have been applied to Gram-positive as well as Gram-negative bacteria 35 . Using variations on this common theme, vacuoles containing mycobacteria (M. tuberculosis and M. avium) 10, 36 , Chlamydia psittaci 37 and Francisella tularensis 38 have been purified and used for comparative electrophoretic gel analysis. The mixing of 35 S-Met metabolically labeled macrophages with nonlabeled M. avium-containing macrophages before lysis did not reveal specific selection of contaminating proteins in purified MCVs, with a global contamination level estimated to be a low 6-8 10 .
The isolation of latex bead-containing phagosomes (LBPs) takes advantage of the low density of latex. After cell lysis, LBP isolation is performed via flotation on a sucrose step gradient in one separative centrifugation step. The method was first developed in Acanthamoeba castellanii 2 , but it has now been used for proteomics in all the common phagocytic models, including Dictyostelium discoideum 14, 15 , Entamoeba histolytica 16, 17 , Tetrahymena thermophila 18 , Drosophila melanogaster S2 cells 3 , mouse and human macrophage cell lines 5, 19-23 and human neutrophils 24 . A range of detailed protocols have been published 22, 25, 26 . As the potential contaminations of LBP preparations have been much debated, many control experiments have been performed to assess LBP purity. This exhaustive list of experiments exemplifies which approaches can be used to check and improve the purity of a phagosome preparation. Flotation of LBPs on sucrose gradients yields up to 50-fold enrichment and...
Early in vitro experiments used formaldehyde-fixed Staphylococcus aureus as phagocytic probe 9 . These bacteria bind the constant part of IgG antibodies via their surface Protein A and therefore expose free variable (Fab) parts. This feature makes them particularly suitable for the creation of an in vitro fusion assay as they can be used as affinity reagents for any molecule to which a specific antibody is available. Phagosomes containing antibody-coated S. aureus are fused with endosomes enclosing a corresponding antigen-enzyme complex (e.g., anti-dinitrophenol antibody dinitrophenol-derivatized b-glucuronidase). Fusion of both kinds of organelles can then be quantified as bacteria-associated enzyme activity (Figure 6.1a). An antigen-bovine serum albumin (BSA) conjugate present in the reaction buffer functions as a scavenger and impedes mutual binding of antibody-coated bacteria and antigen-enzyme complexes from broken organelles. In more recent approaches bacteria were substituted...
Since chloroplasts in many plant species accumulate significant amounts of starch during the light period, it may be pertinent to consider how these starch-laden chloroplasts differ from amyloplasts where starch storage is more long term. Transient starch in chloroplasts has a lower amylose content, forms as flattened plate-like structures rather than the more spherical grains of amyloplasts and does not possess the growth rings of amyloplast starch (A. Smith, personal communication). In some species such a tobacco and cotton, starch breakdown in older leaves is not complete by dawn and starch accumulates in these older leaf cells, taking on some properties of long-term storage starch. Conversely some species synthesise very little starch in the chloroplast at all during the light period and export their photosynthate and synthesise sucrose in the cytosol (Zeeman et al. 2004).
And alanine could be obtained when a mixture of reduced gases was exposed to an electrical discharge. The mixture was assumed to be a simulation of the original terrestrial atmosphere which, by analogy with the outer planets, would have contained hydrogen, methane, ammonia, and water vapour. At sufficiently high energy fluxes, such mixtures of reducing gases generate hydrogen cyanide and formaldehyde, which in turn react to produce amino acids, purines, and a variety of simple sugars.
Bees are among the most important insects. They process the nectar of flowers to produce honey, a sugary liquid that humans use as a sweetener and nutrient. The nutritive component of honey is pure carbohydrate in the form of simple sugars, which are directly absorbed by the body. This characteristic gives honey its punch as a quick energy source. Edible in its natural state, it can also be used as an ingredient of desserts or to sweeten drinks. Not only bees, however, but also wasps play a fundamental role in the lives of all living beings. Many plants depend on them for pollination of their flowers. Without these insects there would be fewer fruits and vegetables to eat.
'Formaldehyde is another key molecule. Again it is very small, containing only one carbon, one oxygen and two hydrogen atoms. It can be formed in a number of ways - for example from ultraviolet sunlight on minerals in the presence of water and carbon dioxide. The wonderful thing about formaldehyde molecules is that they easily join together to give sugar molecules of all sorts. Several molecules of life are simple sugars. These contain carbon, oxygen and hydrogen atoms in the same proportion as in formaldehyde. Glucose is such a molecule. Often they have a ring of atoms, making a fairly rigid little unit that is useful for building purposes. (The connector pieces of nucleotides contain sugar units.)'
Lactose, for example, causes E. coli to hedge its bets. A supply of lactose may allow bacteria to survive when other kinds of sugar have been devoured. But in order to feed on lactose, a microbe first has to clear away all the proteins it was using to feed on other sugars and begin making the proteins it needs to eat lactose. That's a lot of time and energy for a microbe to invest. The investment may pay off or it may be a waste of effort the lactose may disappear quickly or a more energy-rich sugar may turn up.
Just as important as the genes Shigella gained were the ones it lost. Flagella are wonderful for swimming in the gut, but they are useless inside the crammed interior of a host cell. No Shigella strain can make flagella, although they all still carry disabled copies of the flagella-building genes. Shigella also has disabled copies of genes for eating lactose and other sugars that it no longer feeds on. And it has abandoned an enzyme called cadaverine, which other strains of E. coli make to protect themselves from acid. (Other bacteria produce this foul-smelling
Disaccharide such as trehalose in microbes, animals, and fungi, or sucrose in plants, is sufficient to survive desiccation (Crowe et al., 1992). Trehalose may provide effective protection against desiccation because it has superior biochemical and physicochemical properties for stabilizing membranes and biomolecules including proteins and lipids (Watanabe, 2006) by hydrogen bonding to polar residues in the dry macromolecular assemblages (Crowe etal., 1998). However, both trehalose and sucrose form glasses in the dry state so it has been suggested that glass formation (vitrification) is in itself sufficient to stabilize dry biomolecules (Sun et al., 1998). Crowe et al. (1998) have shown that, while vitrification is required, it is not in itself sufficient to allow anhydrobiosis.
Latex bead phagosomes can be purified by flotation in a sucrose gradient under different conditions, for example, different time-points. This allows the study ofthe influence of proteins and lipids present on the phagosomal membrane in actin binding or assembly (Figure 8.3). In addition, LBPs can be incubated with different Figure 8.3 In vitro assays to monitor actin in latex bead phagosomes (LBPs). (a) Scheme showing the purification of LBPs from macrophages for biochemical analysis. Briefly, latex beads are internalized and then isolated using its property offlotation in a sucrose gradient. Then isolated LBPs are used for the assays described below. (b) Assays to assess the role of actin in phagosome biology. (1) Actin nucleation assay, with this approach LBPs are used in presence of ATP and the nucleation of actin filaments around the phagosome measured 35 . (2) Actin binding, actin is polymerized and then phagosomes incubated with this actin network. Filamentous actin stabilized...
The Sugar Solution
Curb Sugar Cravings Once And For All With These Powerful Techniques. Sugar sensitive people might be low in specific neurochemicals that help us feel calm, centered, confident, and optimistic. Sugar is a drug that temporarily makes the sugar sensitive feel better, but with damaging consequences.