Effects of Consuming Xylitol on Gut Microbiota and Lipid Metabolism in Mice

The sugar alcohol xylitol inhibits the growth of some bacterial species including Streptococcus mutans. It is used as a food additive to prevent caries. We previously showed that 1.5–4.0 g/kg body weight/day xylitol as part of a high-fat diet (HFD) improved lipid metabolism in rats. However, the effects of lower daily doses of dietary xylitol on gut microbiota and lipid metabolism are unclear. We examined the effect of 40 and 200 mg/kg body weight/day xylitol intake on gut microbiota and lipid metabolism in mice. Bacterial compositions were characterized by denaturing gradient gel electrophoresis and targeted real-time PCR. Luminal metabolites were determined by capillary electrophoresis electrospray ionization time-of-flight mass spectrometry. Plasma lipid parameters and glucose tolerance were examined. Dietary supplementation with low- or medium-dose xylitol (40 or 194 mg/kg body weight/day, respectively) significantly altered the fecal microbiota composition in mice. Relative to mice not fed xylitol, the addition of medium-dose xylitol to a regular and HFD in experimental mice reduced the abundance of fecal Bacteroidetes phylum and the genus Barnesiella, whereas the abundance of Firmicutes phylum and the genus Prevotella was increased in mice fed an HFD with medium-dose dietary xylitol. Body composition, hepatic and serum lipid parameters, oral glucose tolerance, and luminal metabolites were unaffected by xylitol consumption. In mice, 40 and 194 mg/kg body weight/day xylitol in the diet induced gradual changes in gut microbiota but not in lipid metabolism

AUTS2 Governs Cerebellar Development, Purkinje Cell Maturation, Motor Function and Social Communication

Autism susceptibility candidate 2 (AUTS2), a risk gene for autism spectrum disorders (ASDs), is implicated in telencephalon development. Because AUTS2 is also expressed in the cerebellum where defects have been linked to ASDs, we investigated AUTS2 functions in the cerebellum. AUTS2 is specifically localized in Purkinje cells (PCs) and Golgi cells during postnatal development. Auts2 conditional knockout (cKO) mice exhibited smaller and deformed cerebella containing immature-shaped PCs with reduced expression of Cacna1a. Auts2 cKO and knock-down experiments implicated AUTS2 participation in elimination and translocation of climbing fiber synapses and restriction of parallel fiber synapse numbers. Auts2 cKO mice exhibited behavioral impairments in motor learning and vocal communications. Because Cacna1a is known to regulate synapse development in PCs, it suggests that AUTS2 is required for PC maturation to elicit normal development of PC synapses and thus the impairment of AUTS2 may cause cerebellar dysfunction related to psychiatric illnesses such as ASDs

Behavioral Characteristics of Ubiquitin-Specific Peptidase 46-Deficient Mice

<div><p>We have previously identified <i>Usp46,</i> which encodes for ubiquitin-specific peptidase 46, as a quantitative trait gene affecting the immobility time of mice in the tail suspension test (TST) and forced swimming test. The mutation that we identified was a 3-bp deletion coding for lysine (Lys 92), and mice with this mutation (MT mice), as well as <i>Usp46</i> KO mice exhibited shorter TST immobility times. Behavioral pharmacology suggests that the gamma aminobutyric acid A (GABA_A) receptor is involved in regulating TST immobility time. In order to understand how far <i>Usp46</i> controls behavioral phenotypes, which could be related to mental disorders in humans, we subjected <i>Usp46</i> MT and KO mice to multiple behavioral tests, including the open field test, ethanol preference test, ethanol-induced loss of righting reflex test, sucrose preference test, novelty-suppressed feeding test, marble burying test, and novel object recognition test. Although behavioral phenotypes of the <i>Usp46</i> MT and KO mice were not always identical, deficiency of <i>Usp46</i> significantly affected performance in all these tests. In the open field test, activity levels were lower in <i>Usp46</i> KO mice than wild type (WT) or MT mice. Both MT and KO mice showed lower ethanol preference and shorter recovery times after ethanol administration. Compared to WT mice, <i>Usp46</i> MT and KO mice exhibited decreased sucrose preference, took longer latency periods to bite pellets, and buried more marbles in the sucrose preference test, novelty-suppressed feeding test, and marble burying test, respectively. In the novel object recognition test, neither MT nor KO mice showed an increase in exploration of a new object 24 hours after training. These findings indicate that <i>Usp46</i> regulates a wide range of behavioral phenotypes that might be related to human mental disorders and provides insight into the function of USP46 deubiquitinating enzyme in the neural system.</p> </div

Novel object recognition test.

<p>(A) Number of explorations of the 2 objects on the training day. Compared to WT mice, <i>Usp46</i> KO mice showed significantly lower numbers of explorations for each object. The number of explorations for object B made by KO mice was also significantly lower than that by MT mice. (B) A familiar object was substituted by a novel object at 24 hours after the training. The number of explorations for the novel object was significantly increased for the WT mice, but not for <i>Usp46</i> MT and KO mice. (C) Total number of explorations for the objects on the training day and 24 hours after the training. The number of explorations made by KO mice was significantly lower than those by WT or MT mice. The number of mice used is shown within parentheses. One-way ANOVA with Fisher's PLSD test; *<i>P</i><0.05, **<i>P</i><0.01. Student's <i>t</i> test; ^#<i>P</i><0.05.</p

Open field test.

<p>Total distance of movement (A), number of climbing and rearing events (B), time spent in the outer zone (C), and resting time in the outer zone (D) of an open field for 5 min. <i>Usp46</i> KO mice showed significantly lower values than WT and MT mice for the total distance of movement and the number of climbing and rearing events. Nonmoving time in the outer zone was significantly higher for KO mice. The number of mice used is shown within parentheses. One-way ANOVA with Fisher's PLSD test; *<i>P</i><0.05, **<i>P</i><0.01.</p

Novelty-suppressed feeding test.

<p>(A) <i>Usp46</i> MT and KO mice showed an increased latency time to bite pellets in a test box. (B) Feeding time in the test box for 10 min. KO mice exhibited significantly lower feeding times. (C) Feeding time in the home cage for 5 min. The KO mice showed significantly longer feeding times. (D) Total food consumption (in the test box for 10 min, and the home cage for 5 min) was not significantly different between the MT, KO, and WT mice. The number of mice used is shown within parentheses. One-way ANOVA with Fisher's PLSD test; *<i>P</i><0.05, **<i>P</i><0.01.</p

Effects of Consuming Xylitol on Gut Microbiota and Lipid Metabolism in Mice

The sugar alcohol xylitol inhibits the growth of some bacterial species including Streptococcus mutans. It is used as a food additive to prevent caries. We previously showed that 1.5–4.0 g/kg body weight/day xylitol as part of a high-fat diet (HFD) improved lipid metabolism in rats. However, the effects of lower daily doses of dietary xylitol on gut microbiota and lipid metabolism are unclear. We examined the effect of 40 and 200 mg/kg body weight/day xylitol intake on gut microbiota and lipid metabolism in mice. Bacterial compositions were characterized by denaturing gradient gel electrophoresis and targeted real-time PCR. Luminal metabolites were determined by capillary electrophoresis electrospray ionization time-of-flight mass spectrometry. Plasma lipid parameters and glucose tolerance were examined. Dietary supplementation with low- or medium-dose xylitol (40 or 194 mg/kg body weight/day, respectively) significantly altered the fecal microbiota composition in mice. Relative to mice not fed xylitol, the addition of medium-dose xylitol to a regular and HFD in experimental mice reduced the abundance of fecal Bacteroidetes phylum and the genus Barnesiella, whereas the abundance of Firmicutes phylum and the genus Prevotella was increased in mice fed an HFD with medium-dose dietary xylitol. Body composition, hepatic and serum lipid parameters, oral glucose tolerance, and luminal metabolites were unaffected by xylitol consumption. In mice, 40 and 194 mg/kg body weight/day xylitol in the diet induced gradual changes in gut microbiota but not in lipid metabolism

Design and synthesis of strong root gravitropism inhibitors with no concomitant growth inhibition

Abstract Herein, we describe a highly potent gravitropic bending inhibitor with no concomitant growth inhibition. Previously, we reported that (2Z,4E)-5-phenylpenta-2,4-dienoic acid (ku-76) selectively inhibits root gravitropic bending of lettuce radicles at 5 μM. Based on the structure–activity relationship study of ku-76 as a lead compound, we designed and synthesized various C4-substituted analogs of ku-76. Among the analogs, 4-phenylethynyl analog exhibited the highest potency for gravitropic bending inhibition, which was effective at only 0.01 μM. Remarkably, 4-phenylethynyl analog is much more potent than the known inhibitor, NPA. Substitution in the para position on the aromatic ring of 4-phenylethynyl group was tolerated without diminished activity. In addition, evaluation using Arabidopsis indicated that 4-phenylethynyl analog inhibits gravitropism by affecting auxin distribution in the root tips. Based on the effects on Arabidopsis phenotypes, 4-phenylethynyl analog may be a novel inhibitor that differs in action from the previously reported auxin transport inhibitors