Effects of hypergravity on expression of XTH genes in azuki bean epicotyls

Hypergravity produced by centrifugation caused inhibition of elongation growth and a decrease in the cell wall extensibility in azuki bean epicotyls ( Vigna angularis Ohwi et Ohashi). Also, hypergravity increased the molecular mass of xyloglucans, whereas it decreased xyloglucan-degrading activity in epicotyls. When the expression profiles of three xyloglucan endotransglucosylase/hydrolase ( XTH ) genes, VaXTHS4 , VaXTH1 and VaXTH2 , were analyzed under hypergravity conditions, the expression of VaXTHS4 , which shows only hydrolase activity, was downregulated in proportion to the logarithm of the magnitude of gravity (R = −0.94). However, the gene expression of VaXTH1 or VaXTH2 , which shows only transglucosylase activity, was not affected by gravitational conditions. When the seedlings that had been grown at 1  g were transferred to hypergravity conditions at 300  g , the downregulation of VaXTHS4 expression was detected within 1 h. By removal of hypergravity stimulus, VaXTHS4 expression was increased within 1 h. These results suggest that azuki bean epicotyls promptly regulate the expression level of only VaXTHS4 in response to gravity stimuli. The regulation of xyloglucan-hydrolyzing activity as a result of changes in VaXTHS4 expression may be involved in the regulation by gravity of molecular mass of xyloglucans, leading to modifications of cell wall mechanical properties and cell elongation. Lanthanum and gadolinium, potential blockers of mechanosensitive calcium ion permeable channels (mechanoreceptors), nullified the suppression of VaXTHS4 expression, suggesting that mechanoreceptors are responsible for inhibition by hypergravity of VaXTHS4 expression.     

Modification of chemical properties of cell walls by silicon and its role in regulation of the cell wall extensibility in oat leaves

Effects of silicon on the mechanical and chemical properties of cell walls in the second leaf of oat (Avena sativa L.) seedlings were investigated. The cell wall extensibility in the basal region of the second leaf was considerably higher than that in the middle and subapical regions. Externally applied silicon increased the cell wall extensibility in the basal region, but it did not affect the extensibility in the middle and subapical regions. The amounts of cell wall polysaccharides and phenolic compounds, such as diferulic acid (DFA) and ferulic acid (FA), per unit length were lower in the basal region than in the middle and subapical regions of the leaf, and silicon altered these amounts in the basal region. In this region, silicon decreased the amounts of matrix polymers and cellulose per unit length and of DFA and FA, both per unit length and unit matrix polymer content. Silicon treatment also lowered the activity of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) in the basal region. In contrast, the amount of silicon in cell walls increased in response to silicon treatment in three regions. These results suggest that in the basal region, silicon reduces the net wall mass and the formation of phenolic acid-mediated cross-linkages between wall polysaccharides. Such modifications of wall architecture may be responsible for the silicon-induced increase in the cell wall extensibility in oat leaves.     

External and internal flavonoids from Madagascarian Uncarina species (Pedaliaceae)

External and internal flavonoids were isolated from 12 Uncarina taxa (Pedaliaceae), endemic to Madagascar. Four flavone aglycones, tricetin 7,3′,5′-trimethyl ether, tricetin 7,4′,5′-trimethyl ether, 5,3′-dihydroxy-6,7,4′,5′-tetramethoxyflavone and eupatorin were isolated from leaf wax of seven Uncarina taxa, Uncarina grandidieri, Uncarina decaryi, Uncarina abbreviata, Uncarina turicana, Uncarina platycarpa, Uncarina leandrii var. leandrii and Uncarina peltata, but not Uncarina stellulifera, Uncarina perrieri, Uncarina sakalava, Uncarina leptocarpa and U. leandrii var. rechbergeri. Furthermore, eight flavonoid glycosides were isolated from the leaves. Major glycosides were apigenin and luteolin 7-O-glucuronides and occurred in all the Uncarina taxa examined, except the absence of the former compound in U. peltata. Other glycosides were identified as hispidulin, jaceosidin, chrysoeriol and tricin 7-O-glucuronides, and luteolin 7,4′-di-O-glucuronide and a flavonol, isorhamnetin 3-O-diglucoside. From the results described above, methylated flavone aglycones and glucuronides were chemical characters of the leaves of Uncarina species, and also may be those of the family Pedaliaceae. Besides, an anthocyanin, two flavonols and three flavones were isolated from the flowers of U. grandidieri, and identified as cyanidin 3-O-rutinoside (anthocyanin), quercetin and isorhamnetin 7-O-glucuronides (flavonols) and apigenin, luteolin and jaceosidin 7-O-glucuronides (flavones).     

Mice lacking alpha1,3-fucosyltransferase IX demonstrate disappearance of Lewis x structure in brain and increased anxiety-like behaviors

The 3-fucosyl-N-acetyllactosamine [Lewis x (Le(x)), CD15, SSEA-1] carbohydrate structure is expressed on several glycolipids, glycoproteins, and proteoglycans of the nervous system and has been implicated in cell-cell recognition, neurite outgrowth, and neuronal migration during development. To characterize the functional role of Le(x) carbohydrate structure in vivo, we have generated mutant mice that lack alpha1,3-fucosyltransferase IX (Fut9(-/-)). Fut9(-/-) mice were unable to synthesize the Le(x) structure carried on glycoproteins and glycolipids in embryonic and adult brain. However, no obvious pathological differences between wild-type and Fut9(-/-) mice were found in brain. In behavioral tests, Fut9(-/-) mice exhibited increased anxiety-like responses in dark-light preference and in elevated plus maze tests. Immunohistochemical analysis showed that the number of calbindin-positive neurons was decreased in the basolateral amygdala in Fut9(-/-) mice. These observations indicated that the carbohydrates synthesized by Fut9 play critical roles in functional regulations of interneurons in the amygdalar subdivisions and suggested a role for the Le(x) structure in some aspects of emotional behavior in mice.     

A peculiar relationship between genetic diversity and adaptability in invasive exotic species: bluegill sunfish as a model species

A peculiar relationship exists between population genetics and invasion biology. Introduced populations often suffer a depletion of genetic variation, but they can persist and adapt to new environments. Here, we show that this relationship is observed in bluegill sunfish (Lepomis macrochirus), an invasive exotic fish in Japan. Genetic analysis using selectively neutral genetic markers reconfirmed that the bluegill introduced into Japan from the United States in 1960 had a single origin with only 15 founders. The analysis also shows that in the process of range expansion, the introduced bluegills experienced severe depletion of genetic diversity due to the founder effect and/or genetic drift. Despite such a decline in genetic diversity, the bluegill populations exhibited a divergent feeding morphology in response to the colonized environments. Such a morphological divergence can facilitate prey exploitation, thereby causing a greater negative impact on native prey resources. Further, in a trophically polymorphic bluegill population in Lake Biwa, physiological characteristics and genetic structures of the intestinal bacterial communities were associated with the difference in diet among the trophic morphs in the host bluegill population. This empirical evidence suggests that despite the severe decline in genetic diversity, the introduced bluegill populations rapidly adapted to the new environment and formed diverse functional relationships with the native bacterial community. Thus, these findings suggest that genetic variation at selectively neutral markers does not always predict adaptability and invasiveness in introduced populations.     

Clinical application of Clostridium botulinum type A neurotoxin purified by a simple procedure for patients with urinary incontinence caused by refractory destrusor overactivity

Type A neurotoxin of Clostridium botulinum was purified by a simple procedure using a lactose gel column. This procedure was previously reported for type B neurotoxin. Hemagglutinin-positive toxins (19S and 16S) were bound to the column under acid conditions, and the neurotoxin alone was dissociated from these hemagglutinin-positive toxins by changing the pH of the column to an alkaline condition. The toxicity of this purified toxin preparation was retained for at least 1 year at -30 degrees C by supplementing it with either 0.1% albumin or 0.05% albumin plus 1% trehalose. This preparation was used to treat 18 patients with urinary incontinence caused by refractory idiopathic and neurogenic detrusor overactivity; 16 of the patients showed excellent improvement. Improvements started within 1 week after injection in most cases and lasted 3-12 months [corrected]     

Rab27b regulates mast cell granule dynamics and secretion

The Rab GTPase family regulates membrane domain organization and vesicular transport pathways. Recent studies indicate that one member of the family, Rab27a, regulates transport of lysosome-related organelles in specialized cells, such as melanosomes and lytic granules. Very little is known about the related isoform, Rab27b. Here we used genetically modified mice to study the involvement of the Rab27 proteins in mast cells, which play key roles in allergic responses. Both Rab27a and Rab27b isoforms are expressed in bone marrow-derived mast cells (BMMC) and localize to secretory granules. Nevertheless, secretory defects as measured by beta-hexosaminidase release in vitro and passive cutaneous anaphylaxis in vivo were found only in Rab27b and double Rab27 knockout (KO) mice. Immunofluorescence studies suggest that a subset of Rab27b and double Rab27-deficient BMMCs exhibit mild clustering of granules. Quantitative analysis of live-cell time-lapse imaging revealed that BMMCs derived from double Rab27 KO mice showed almost 10-fold increase in granules exhibiting fast movement (>1.5 microm/s), which could be disrupted by nocodazole. These results suggest that Rab27 proteins, particularly Rab27b, play a crucial role in mast cell degranulation and that their action regulates the transition from microtubule to actin-based motility.     

Wheat bran protects Fischer-344 rats from diquat-induced oxidative stress by activating antioxidant system: selenium as an antioxidant

Wheat bran had a protective effect against diquat toxicity in rats fed a purified diet (PD). We studied the effects of wheat bran on the antioxidant system in the liver of rats treated with saline and diquat. Although feeding wheat bran did not affect the concentration of hepatic non-protein sulfhydryl or the activity of glucose 6-phosphate dehydrogenase in the saline-injected rats, these values were significantly higher in the rats fed PD containing wheat bran (W-PD) than in rats fed only PD after administering diquat. The glutathione peroxidase and reductase activities were significantly elevated by wheat bran in the saline-injected rats. Although the glutathione peroxidase activity was unchanged in both the PD-fed rats and W-PD-fed rats after the diquat treatment, the glutathione reductase activity was significantly decreased in both the PD-fed and W-PD-fed rats. Feeding the rats with PD containing 0.15 ppm selenium as well as with W-PD elevated the activity of hepatic glutathione peroxidase and attenuated the diquat toxicity. These results indicate that wheat bran protected against diquat toxicity by activating the hepatic antioxidant system, and that selenium was the key antioxidant in wheat bran.