Combining Lemon and Glycerin may Beneficially Regulate Blood Glucose Levels by Modulating Gut Microbiota in Non-obese Diabetic Mice

Both dietary lemon and glycerin have shown beneficial effects in diabetic humans and animals. It was hypothesized that there were potential therapeutic advantages of combining both agents in hyperglycemic and healthy mice. In a 6-month study using mature adult male non-obese diabetic (NOD) mice, oral treatment with either lemon or glycerin alone increased blood glucose levels during the third month glucose tolerance test and decreased the activity of the predicted glycolysis/gluconeogenesis pathways when compared to the vehicle control; however, this was no longer observed when lemon and glycerin were combined. Metabolomic analysis indicated that acetate was increased in the fecal samples after treatment with either glycerin or the combination. A 2-month study was also conducted in both male and female NOD mice and suggested that there were more gut microbiome changes at one month in comparison to six months. In older NOD male mice, treatment with the combination for six months decreased insulin resistance. In both adult male and female C57BL/6 mice, dosing with the combination for two months decreased blood glucose levels, as well as glucose tolerance and insulin resistance. In addition, treatment with the combination decreased body weights, especially in male mice, in all four studies. Overall, these studies suggest that lemon and glycerin in combination may reduce the side effects of individual treatments (e.g., transient hyperglycemia) and have some additional benefits (e.g., weight loss). Microbiome modulation likely contributed to the observed beneficial effects

Structural Biology: Practical NMR Applications

This textbook begins with an overview of NMR development and applications in biological systems. It describes recent developments in instrument hardware and methodology. Chapters highlight the scope and limitation of NMR methods. While detailed math and quantum mechanics dealing with NMR theory have been addressed in several well-known NMR volumes, chapter two of this volume illustrates the fundamental principles and concepts of NMR spectroscopy in a more descriptive manner. Topics such as instrument setup, data acquisition, and data processing using a variety of offline software are discussed. Chapters further discuss several routine stategies for preparing samples, especially for macromolecules and complexes. The target market for such a volume includes researchers in the field of biochemistry, chemistry, structural biology and biophysics

Two Biosynthetic Pathways for Aromatic Amino Acids in the Archaeon Methanococcus maripaludis

Methanococcus maripaludis is a strictly anaerobic, methane-producing archaeon. Aromatic amino acids (AroAAs) are biosynthesized in this autotroph either by the de novo pathway, with chorismate as an intermediate, or by the incorporation of exogenous aryl acids via indolepyruvate oxidoreductase (IOR). In order to evaluate the roles of these pathways, the gene that encodes the third step in the de novo pathway, 3-dehydroquinate dehydratase (DHQ), was deleted. This mutant required all three AroAAs for growth, and no DHQ activity was detectible in cell extracts, compared to 6.0 ± 0.2 mU mg(−1) in the wild-type extract. The growth requirement for the AroAAs could be fulfilled by the corresponding aryl acids phenylacetate, indoleacetate, and p-hydroxyphenylacetate. The specific incorporation of phenylacetate into phenylalanine by the IOR pathway was demonstrated in vivo by labeling with [1-(13)C]phenylacetate. M. maripaludis has two IOR homologs. A deletion mutant for one of these homologs contained 76, 74, and 42% lower activity for phenylpyruvate, p-hydoxyphenylpyruvate, and indolepyruvate oxidation, respectively, than the wild type. Growth of this mutant in minimal medium was inhibited by the aryl acids, but the AroAAs partially restored growth. Genetic complementation of the IOR mutant also restored much of the wild-type phenotype. Thus, aryl acids appear to regulate the expression or activity of the de novo pathway. The aryl acids did not significantly inhibit the activity of the biosynthetic enzymes chorismate mutase, prephenate dehydratase, and prephenate dehydrogenase in cell extracts, so the inhibition of growth was probably not due to an effect on these enzymes

Mutations of Arabidopsis TBL32 and TBL33 Affect Xylan Acetylation and Secondary Wall Deposition.

Xylan is a major acetylated polymer in plant lignocellulosic biomass and it can be mono- and di-acetylated at O-2 and O-3 as well as mono-acetylated at O-3 of xylosyl residues that is substituted with glucuronic acid (GlcA) at O-2. Based on the finding that ESK1, an Arabidopsis thaliana DUF231 protein, specifically mediates xylan 2-O- and 3-O-monoacetylation, we previously proposed that different acetyltransferase activities are required for regiospecific acetyl substitutions of xylan. Here, we demonstrate the functional roles of TBL32 and TBL33, two ESK1 close homologs, in acetyl substitutions of xylan. Simultaneous mutations of TBL32 and TBL33 resulted in a significant reduction in xylan acetyl content and endoxylanase digestion of the mutant xylan released GlcA-substituted xylooligomers without acetyl groups. Structural analysis of xylan revealed that the tbl32 tbl33 mutant had a nearly complete loss of 3-O-acetylated, 2-O-GlcA-substituted xylosyl residues. A reduction in 3-O-monoacetylated and 2,3-di-O-acetylated xylosyl residues was also observed. Simultaneous mutations of TBL32, TBL33 and ESK1 resulted in a severe reduction in xylan acetyl level down to 15% of that of the wild type, and concomitantly, severely collapsed vessels and stunted plant growth. In particular, the S2 layer of secondary walls in xylem vessels of tbl33 esk1 and tbl32 tbl33 esk1 exhibited an altered structure, indicating abnormal assembly of secondary wall polymers. These results demonstrate that TBL32 and TBL33 play an important role in xylan acetylation and normal deposition of secondary walls

Kinetic properties of the PtrGXM methyltransferase activities.

<p>Recombinant PtrGXM proteins were assayed for the methyltransferase activity in the presence of various concentrations of the (GlcA)Xyl₄ acceptor. The results were analyzed by Lineweaver-Burk plots to determine the <i>K</i>_m and <i>V</i>_max values.</p