Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To examine the effects of prenatal exposure to ethanol on postnatal development of small intestinal and liver functions, female rats were accustomed to increasing amounts of ethanol (10 to 25%, vol/vol) in tap water for 1 mo. During pregnancy, ethanol-fed dams had higher daily caloric intake and similar weight gain compared with controls. In ethanol offspring, neonatal mortality was 28.9% compared to 0% in controls. Although ethanol had been withdrawn at birth, pups issued from ethanol-treated mothers showed at 5 and 10 d postpartum decreased values of body weight, jejunal and ileal weights, and intestinal DNA concentration per unit of length, as well as lower specific and total activities in lactase and maltase, compared with controls. DNA synthesis rates, measured by the incorporation of [3H]thymidine into mucosal DNA, were also significantly (-20 to -34%, p < 0.01) depressed in the jejunum and ileum of ethanol pups at 5 and 10 d of age. All these parameters returned to control levels by d 15 postpartum. Electron microscopy of jejunal mucosal samples at 5, 10, and 15 d of age revealed that ethanol pups differed from controls by a fetal-like immature aspect of the enterocytes, which persisted up to d 15. The ontogenic upsurge in sucrase and the decline in lactase occurred at weaning with the same chronology in both groups, but the level reached by sucrase activity was about 50% lower in alcohol offspring than in controls. Except for moderate steatosis, the ultrastructure of hepatocytes was unaltered in sucklings.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prenatal exposure to ethanol in rats: effects on postnatal maturation of the small intestine and liver. 148 Apr 59

The effect of supplementation of the diet with galactose on the age-related decline of intestinal lactase activity was investigated in 108 growing rats. Starting from 14 days of age, the rats were divided into two groups and fed with chow, and with fluid either as tap water or 5% galactose solution. At 14 days the specific lactase activity was 112.8 +/- 3.2 mumol min-1 (g protein)-1, which decreased to less than 10% of this value at maturity. Galactose supplementation did not prevent the decline. The increase of maltase, sucrase and trehalase was also unaffected. The result suggests that galactose plays no significant role in the regulation of disaccharidase activities in the rat.
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PMID:The effect on intestinal disaccharidase activity of feeding galactose to growing rats. 224 21

The effect of chronic intragastric infusion of hypertonic mannitol on small intestinal mucosal structure and function was studied in adult rats. Animals were gavage-fed 20% mannitol (1300 mosm) at a dose of 5 ml/100 g body weight daily for seven days. Control animals were gavage-fed tap water on the same schedule. On day 8, the animals were anesthetized, the duodenum cannulated, and a test sugar (glucose, glucose polymer, lactose, sucrose, or maltose) was infused at a dose of 0.5 g/kg body weight in 2.5 ml distilled water over less than 1 min. Portal vein glucose was measured at 30-min intervals from 0 to 120 min. Mannitol treatment resulted in histologic and biochemical alterations (reduced lactase, sucrase, maltase) limited to the proximal small intestine compared to the control group. The absorption of glucose and glucose polymers was similar in mannitol-treated and control animals. In contrast, digestion and absorption of lactose, sucrose, and maltose was significantly diminished in mannitol-treated animals when compared to controls. No changes in permeability to polyethylene glycol 4000 or Na+-coupled glucose transport were observed in mannitol-treated animals compared to controls. These data suggest that when the intestinal mucosa is exposed to hyperosmolar loads that the digestive capacity for disaccharides is suppressed more than its glucose absorptive capacities. Furthermore, glucose oligomers may be more readily digested and absorbed than disaccharides, in this setting, due, in part, to the proximal injury and less pronounced proximal-distal gradient for glucoamylase than other brush-border carbohydrases.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Proximal small intestinal mucosal injury. Maintenance of glucose and glucose polymer absorption, attenuation of disaccharide absorption. 249 65

Three genomic clones (Inv*Dc1, Inv*Dc2 and Inv*Dc3) were isolated by using the cDNA for carrot cell wall beta-fructofuranosidase as a probe. The expression patterns of the three genes differed markedly. High levels of Inv*Dc1 transcripts were found in leaves and roots of young carrot, whereas in plants with developing tap roots no transcripts were detected. A high level of mRNA of Inv*Dc1 was also present in suspension-cultured cells. In developing reproductive organs, only low levels of transcripts of Inv*Dc1 were found in flower buds and flowers and none at later stages of development. In contrast, Inv*Dc2 and Inv*Dc3 were not expressed in vegetative plant organs. Invb1*Dc1 was exclusively and strongly expressed in flower buds, and Inv*Dc3 at a very low level in suspension-cultured cells.
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PMID:Structural organization and differential expression of carrot beta-fructofuranosidase genes: identification of a gene coding for a flower bud-specific isozyme. 778 83

Carrot cell wall beta-fructosidase, previously purified and cloned, is encoded by a single, wound- and pathogen-inducible gene. The developmental regulation of the gene was studied by determining the steady-state mRNA levels in different organs during carrot development: cell wall beta-fructosidase mRNA was detected in roots and leaves of young plants but not during tap root development. A genomic clone was isolated and characterized. The transcription start site was determined by primer extension analysis. Inspection of the promoter sequence (1488 bp) revealed the presence of sequences with high homology to cis-acting elements for the regulation of plant genes by wounding and infection. The 5'-regulatory sequence was fused to the reporter gene beta-glucuronidase (GUS) and tested in a transient expression assay with carrot suspension cells and wounded carrot root tissue (aged disks of carrot roots). The expression of the GUS gene in the transfected cells proved that the isolated promoter was functional. In transgenic tobacco plants containing the cell wall beta-fructosidase promoter fused to GUS, the reporter gene was predominantly expressed in the shoot and root meristems of young seedlings. No GUS expression was detected in mature tobacco plants, showing that the development-specific regulation of the cell wall beta-fructosidase promoter seen in carrot was maintained in tobacco plants. In contrast, expression of the GUS reporter gene in transgenic tobacco was not wound inducible. To analyze the functional organization of the cell wall beta-fructosidase promoter, a 5'-deletion series was generated and tested in a transient expression assay in protoplasts of Nicotiana plumbaginifolia. Two regions containing putative silencer elements were identified. A comparison of these regions with known silencer elements identified in both regions one copy of the negative dominant cis-acting element found in a chalcone synthase promoter of petunia.
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PMID:Molecular characterization of the gene for carrot cell wall beta-fructosidase. 822 Apr 95

To unravel the functions of cell wall and vacuolar invertases in carrot, we used an antisense technique to generate transgenic carrot plants with reduced enzyme activity. Phenotypic alterations appeared at very early stages of development; indeed, the morphology of cotyledon-stage embryos was markedly changed. At the stage at which control plantlets had two to three leaves and one primary root, shoots of transgenic plantlets did not separate into individual leaves but consisted of stunted, interconnected green structures. When transgenic plantlets were grown on media containing a mixture of sucrose, glucose, and fructose rather than sucrose alone, the malformation was alleviated, and plantlets looked normal. Plantlets from hexose-containing media produced mature plants when transferred to soil. Plants expressing antisense mRNA for cell wall invertase had a bushy appearance due to the development of extra leaves, which accumulated elevated levels of sucrose and starch. Simultaneously, tap root development was markedly reduced, and the resulting smaller organs contained lower levels of carbohydrates. Compared with control plants, the dry weight leaf-to-root ratio of cell wall invertase antisense plants was shifted from 1:3 to 17:1. Plants expressing antisense mRNA for vacuolar invertase also had more leaves than did control plants, but tap roots developed normally, although they were smaller, and the leaf-to-root ratio was 1.5:1. Again, the carbohydrate content of leaves was elevated, and that of roots was reduced. Our data suggest that acid invertases play an important role in early plant development, most likely via control of sugar composition and metabolic fluxes. Later in plant development, both isoenzymes seem to have important functions in sucrose partitioning.
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PMID:Antisense repression of vacuolar and cell wall invertase in transgenic carrot alters early plant development and sucrose partitioning. 992 37

Wounding of sugar beet tap-root causes an induction of invertase activity, which contributes to post-harvest sucrose losses. In this first comprehensive monitoring of wound-induced invertase mRNAs, proteins, enzyme activities, and tissue hexose concentrations, the VI isoform responsible for wound-induced hexose accumulation in mature tap-root could be identified.
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PMID:In wounded sugar beet (Beta vulgaris L.) tap-root, hexose accumulation correlates with the induction of a vacuolar invertase isoform. 1170 88

1. When disks of root tissue from sugar or red beet (Beta vulgaris L.) are washed in running aerated tap water the sucrose contained in them disappears and glucose and fructose are formed. 2. Invertase activity in the disks has been measured by a polarimetric method. Freshly cut tissue has a very low activity, but a considerable increase occurs during the first 3-4 days of washing, the final activity being sufficient to hydrolyse the sucrose contained in the disk within a few hours. 3. Disks of red beet have been cut and shaken in water under aseptic conditions. Sucrose breakdown and invertase development still took place. Microbial contamination is therefore not responsible. 4. Trisaccharides that appear in sugar-beet disks during the washing process have been isolated and identified; their formation also suggests that a higher-plant invertase is acting. 5. The significance of these results is discussed in relation to protein synthesis in washed storage-tissue slices, and the occurrence of high invertase activity in growing plant cells.
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PMID:THE DEVELOPMENT OF INVERTASE ACTIVITY IN SLICES OF THE ROOT OF BETA VULGARIS L. WASHED UNDER ASEPTIC CONDITIONS. 1434 26

The expression pattern of the genes coding for vacuolar and extracellular invertase activity was analyzed in sugar beet (Beta vulgaris) and compared with the expression of sucrose synthase in this important sucrose-storing crop. Northern blot analysis revealed that sucrose synthase is the predominant sucrose-cleaving enzyme in tap roots, whereas vacuolar invertase was specifically expressed in petioles. Extracellular invertase transcripts showed low abundance in all the sugar beet organs and were not detected in northern blots. Relative RT-PCR analysis revealed differential expression of the two extracellular invertase genes: BVInv-CW1 was almost exclusively expressed in tap roots and BVInv-CW2 was widely expressed in all the organs analyzed. A remarkable result of this analysis was the high expression of vacuolar invertase (BVInv-V3) in petioles. Two factors had a clear influence on vacuolar invertase gene expression in petioles: light and the developmental stage, so that expression was higher in petioles from juvenile plants. BVInv-V3 transcripts showed circadian oscillation in petioles, with maximal accumulation during the light period. A similar pattern of diurnal oscillation was also observed for the vacuolar invertase activity, showing a delay with respect to the level of transcripts. The analysis of sugars in petioles revealed oscillation of the hexoses, with a remarkably higher content of glucose than fructose. In contrast, the level of sucrose in petioles was very low. This pattern of expression suggests an important role of petiole vacuolar invertase in plant development and photoassimilate partitioning.
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PMID:Circadian and developmental regulation of vacuolar invertase expression in petioles of sugar beet plants. 1605 18

Sucrose utilisation in sink tissues depend on its cleavage and is mediated by two different classes of enzymes, invertase and sucrose synthase, which determine the mechanism of phloem unloading. Cloning of two extracellular (BIN35 and BIN46) and one vacuolar invertase (BIN44) provided the basis for a detailed molecular analysis of the relative contribution of the sucrose cleaving enzymes to the sink metabolism of sugar beets (Beta vulgaris) during development. The determination of the steady state levels of mRNAs has been complemented by the analysis of the corresponding enzyme activities. The present study demonstrates an inverse regulation of extracellular invertase and sucrose synthase during tap root development indicating a transition between functional unloading pathways. Extracellular cleavage by invertase is the dominating mechanism to supply hexoses via an apoplasmic pathway at early stages of storage root development. Only at later stages sucrose synthase takes over the function of the key sink enzyme to contribute to the sink strength of the tap root via symplasmic phloem unloading. Whereas mRNAs for both extracellular invertase BIN35 and sucrose synthase were shown to be induced by mechanical wounding of mature leaves of adult plants, only sucrose synthase mRNA was metabolically induced by glucose in this source organ supporting the metabolic flexibility of this species.
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PMID:The developmental and organ specific expression of sucrose cleaving enzymes in sugar beet suggests a transition between apoplasmic and symplasmic phloem unloading in the tap roots. 1709 37


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