Highly organized interphase cortical microtubule (MT) arrays are essential for anisotropic growth of plant cells, yet little is known about the molecular mechanisms that establish and maintain the order of these arrays. The Arabidopsis thaliana spiral1 (spr1) mutant shows right-handed helical growth in roots and etiolated hypocotyls. Characterization of the mutant phenotypes suggested that SPR1 may control anisotropic cell expansion through MT-dependent processes. SPR1 was identified by map-based cloning and found to encode a small protein with unknown function. Proteins homologous to SPR1 occur specifically and ubiquitously in plants. Genetic complementation with green fluorescent protein fusion proteins indicated that the SPR1 protein colocalizes with cortical MTs and that both MT localization and cell expansion control are conferred by the conserved N-and C-terminal regions. Strong SPR1 expression was found in tissues undergoing rapid cell elongation. Plants overexpressing SPR1 showed enhanced resistance to an MT drug and increased hypocotyl elongation. These observations suggest that SPR1 is a plant-specific MT-localized protein required for the maintenance of growth anisotropy in rapidly elongating cells.
Acetic acid bacteria, fermentative microorganisms of traditional foods, have unique alkali-stable lipids (ASL), such as dihydroceramide which is a precursor of sphingolipids. Sphingolipids are important components of the brain tissue. We examined the effect of oral administration of ASL in a rat model of dementia (7-week-old, male) with a basal forebrain lesion. In a water maze test, the dementia model rats demonstrated poor spatial orientation. The administration of ASL (165 or 1650 mg/kg of body weight per day, for 14 days) produced a significant improvement in learning ability in the dementia model rats. In vitro experiments showed ASL had the ability to promote neurite outgrowth in pheochromocytoma (PC12) cells. Among the ASL components, dihydroceramide has the most potent effect on the differentiation of PC12 cells. It is highly possible that oral administration of dihydroceramide-containing ASL reverses the decline in cognitive function in dementia.
50The lipid matrix in the stratum corneum is important to the barrier function of mammalian skin. Ceramides are main components of intercellular lipids in the stratum corneum and play an essential role in skin barrier function. Moreover, recent investigations have demonstrated improvement in skin barrier properties after oral intake of ceramides of plant origin in mice and healthy adults. However, beneficial effects on skin barrier function by oral intake of ceramides other than those of plant origin have not been reported.It is known that acetic acid bacteria accumulate intracellular ceramides. Therefore, we examined the dietary effect of ceramide-containing acetic acid bacteria on skin barrier function. Studied were 3 groups, each comprised of 20 healthy adults with awareness of dry skin. The control group was given a placebo, the low acetic acid bacteria group [low-dose group] was given 55.6 mg dry acetic acid bacteria containing 400 μg ceramide, and the high acetic acid bacteria group [high-dose group] was administered 111.1 mg dry acetic acid bacteria containing 800 μg ceramide per day for 8 weeks. Transepidermal water loss (TEWL) and stratum corneum hydration (SCH) were measured as indexes of skin barrier function on the cheek, upper inner arm and back of the neck of all study subjects. The most marked effect was on the cheek, the area most exposed. On the cheek, the TEWL value increased significantly on week 4 after starting administration in the control group, but remained at the baseline level in both the low-dose and high-dose groups. In both the low-dose and high-dose groups, TEWL values decreased significantly on week 6. The SCH value increased significantly after 6 weeks administration in the control group, whereas in both the low-dose and high-dose groups the SCH value increased significantly after just 4 weeks of intake. This increase occurred within a shorter period than in the control group. These results suggest that oral intake of ceramide-containing acetic acid bacteria effects to maintain skin barrier function in healthy adults with awareness of dry skin.
Abstract
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