Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.20 (alpha-glucosidase)
4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transmission electron micrographs of the pea aphid midgut revealed that its anterior region has cells with an apical complex network of lamellae (apical lamellae) instead of the usual regularly-arranged microvilli. These apical lamellae are linked to one another by trabeculae. Modified perimicrovillar membranes (MPM) are associated with the lamellae and project into the lumen. Trabeculae and MPM become less conspicuous along the midgut. The most active A. pisum digestive enzymes are membrane-bound. An aminopeptidase (APN) is described elsewhere. An alpha-glucosidase (alpha-Glu) has a molecular mass of 72 kDa, pH optimum 6.0 and catalyzes in vitro transglycosylations in the presence of an excess of the substrate sucrose. There is a major cysteine proteinase activity (CP) on protein substrates that has a molecular mass of 40 kDa, pH optimum 5.5, is inhibited by E-64 and chymostatin and is activated by EDTA+cysteine. The enzyme is more active against carbobenzoxy-Phe-Arg-4-methylcoumarin-7-amide (ZFRMCA) than against ZRRMCA. These features identify the purified CP as a cathepsin-L-like cysteine proteinase. Most CP is found in the anterior midgut, whereas alpha-Glu and APN predominate in the posterior midgut. With the aid of antibodies, alpha-Glu and CP were immunolocalized in cell vesicles and MPM, whereas APN was localized in vesicles, apical lamellae and MPM. The data suggest that the anterior midgut is structurally reinforced to resist osmotic pressures and that the transglycosylating alpha-Glu, together with CP and APN are bound to MPM, thus being both distributed over a large surface and prevented from excretion with honeydew. alpha-Glu frees glucose from sucrose without increasing the osmolarity, and CP and APN may process toxins or other proteins occasionally present in phloem.
...
PMID:Midgut adaptation and digestive enzyme distribution in a phloem feeding insect, the pea aphid Acyrthosiphon pisum. 1277 12

When fed in semi-artificial diet in short- and long-term bioassays, the lectins from snowdrop (Galanthus nivalis; GNA) and jackbean (Canavalia ensiformis; Con A) affected the activities of soluble and brush border membrane (BBM) enzymes in the midgut of Lacanobia oleracea larvae. In the short term both lectins increased gut protein levels and BBM aminopeptidase activity. The lectins also increased trypsin activity, both in the gut (Con A) and in the faeces (GNA). GNA also increased the activity of alpha-glucosidase, but neither lectin had a significant effect on alkaline phosphatase activity. Trypsin mRNA levels were similar in lectin-fed and control larvae in the short term, showing that there is no direct effect on expression of the encoding genes. Larvae chronically exposed to GNA and Con A showed reductions in weight of 50-60%, and exhibited a significant reduction in alpha-glucosidase activity, but little change in other enzyme activities. Con A bound to many BBM and peritrophic matrix (PM) proteins in vitro, whereas GNA showed more specific binding, with strongest binding to a 94kDa uncharacterised BBM protein. Both lectins accumulated in gut tissues of insects after chronic exposure in vivo, but Con A was present at higher levels than GNA.
...
PMID:A comparison of the short and long term effects of insecticidal lectins on the activities of soluble and brush border enzymes of tomato moth larvae (Lacanobia oleracea). 1277 Mar 21

The rapid development of the gastrointestinal tract posthatch has been described; however, little information exists concerning the development of the small intestine in the prehatch period. The present study examined the morphological, cellular, and molecular changes occurring in the small intestine toward the end of the incubation period by examining the expression of intestinal genes that code for brush border digestive enzymes and transporters, their biochemical activities, and the morphological changes in the mucosal layer. The results indicated that during the last 3 d of incubation the weight of the intestine, as a proportion of embryo weight, increased from approximately 1% on d 17 of embryonic age to 3.5% at hatch. At this time the villi could be divided into two main developmental stages, differing in their length and shape, with the larger villi often being pear-shaped and the smaller villi being narrower and having a rocket-like shape. However, on d 19 a further stage of villus development was observed. Activities of maltase, aminopeptidase, sodium-glucose transporter (SGLT)-1, and ATPase began to increase on d 19 and further increased on the day of hatch. The expression of mRNA for these brush-border membrane (BBM) enzymes and transporters was detected from d 15. Determining quantities relative to beta-actin indicated that expression of all parameters examined was low on d 15 and 17, increased 9- to 25-fold on d 19, and all decreased again on the day of hatch. Relative expression of mRNA of the different enzymes and transporters were correlated as were their activities (r = 0.75 to 0.96); however, expression was not correlated with enzymatic activities. The role of these parameters in the ontogeny of absorption is discussed. Thus, major changes in the expression and localization of the functional brush-border proteins prepare the framework for ingestion of carbohydrate- and protein-rich exogenous feed posthatch.
...
PMID:Morphological, molecular, and functional changes in the chicken small intestine of the late-term embryo. 1465 69

Flowerpiercers are the most specialized nectar-feeding passerines in the Neotropics. They are nectar robbers that feed on the sucrose-rich diet of hummingbirds. To test the hypothesis that flowerpiercers have converged with hummingbirds in digestive traits, we compared the activity of intestinal enzymes and the gut nominal area of cinnamon-bellied flowerpiercers (Diglossa baritula) with those of eleven hummingbird species. We measured sucrase, maltase, and aminopeptidase-N activities. To provide a comparative context, we also compared flowerpiercers and hummingbirds with 29 species of passerines. We analyzed enzyme activity using both standard allometric analyses and phylogenetically independent contrasts. Both approaches revealed the same patterns. With the exception of sucrase activity, hummingbirds' digestive traits were indistinguishable from those of passerines. Sucrase activity was ten times higher in hummingbirds than in passerines. Hummingbirds and passerines also differed in the relationship between intestinal maltase and sucrase activities. Maltase activity was two times higher per unit of sucrase activity in passerines than in hummingbirds. The sucrase activity of D. baritula was much lower than that of hummingbirds, and not unlike that expected for a passerine of its body mass. With the exception of aminopeptidase-N activity, the digestive traits of D. baritula were not different from those of other passerines.
...
PMID:Sugar and protein digestion in flowerpiercers and hummingbirds: a comparative test of adaptive convergence. 1475 1

The intestinal plasticity of digestive enzymes of amphibian species is poorly known. The goal of this study was to characterize digestive enzyme profiles along the small intestine of adult frogs, Xenopus laevis, in response to an experimental diet. We acclimated adult X. laevis for 30 days either to carbohydrate-rich or protein-rich diets, and determined the morphology and digestive enzymes of the small intestine. We found a significant difference of aminopeptidase-N activity between carbohydrate-rich and protein-rich acclimated animals. We also found a little variation in the expression of maltase activity, which contrast with the proposed hypothesis about the existence of digestive tradeoff in vertebrates. This finding supports the adaptive modulation hypothesis and suggests that caution is called for when analyzing physiological data regarding assumed discrete trophic category of species.
...
PMID:Phenotypic flexibility in the intestinal enzymes of the African clawed frog Xenopus laevis. 1566 22

Gut plasticity is a trait with implications on animal performance. However, and despite their importance as study models in physiology, research on gut flexibility in amphibians is scarce. In the present work, we analyse digestive adjustments of Bufo spinulosus adult individuals to cope with changes in diet quality and quantity at two organizational levels (i.e., digestive morphology and enzymes). We found that changes in gut size are related to the amount of food ingested, but not to diet composition. This is in agreement with "the gut seasonal change" hypothesis and offers a proximal explanation for this change. Digestive enzymatic activity (maltase and aminopeptidase-N) did not change with diet quality or quantity, which agrees with the hypothesis of "hard-wired physiology in adult amphibians". Both hypotheses are in agreement with the general theoretical framework of gut phenotypic flexibility when interpreted in light of amphibian natural history. In addition, our results indicate that the correlation between feeding frequency and the level of gut up-regulation proposed for interspecific comparisons may also be found at the intraspecific level.
...
PMID:Digestive morphology and enzyme activity in the Andean toad Bufo spinulosus: hard-wired or flexible physiology? 1574 55

We examined seasonal and age-related variation in digestive organ sizes and enzyme activities in female western sandpipers (Calidris mauri) refueling at a coastal stopover site in southern British Columbia. Adult sandpipers exhibited seasonal variation in pancreatic and intestinal enzyme activities but not in digestive system or organ sizes. Spring migrants had 22% higher total and 67% higher standardized pancreatic lipase activities but 37% lower total pancreatic amylase activity than fall migrants, which suggests that the spring diet was enriched with lipids but low in glycogen. Spring migrants also had 47% higher total intestinal maltase activity as well as 56% higher standardized maltase and 13% higher standardized aminopeptidase-N activities. Spring migrants had higher total enzymic capacity than fall migrants, due primarily to higher total lipase and maltase activities. During fall migration, the juvenile's digestive system was 10% larger than the adult's, and it was composed differently: juveniles had a 16% larger small intestine but a 27% smaller proventriculus. The juvenile's larger digestive system was associated with lower total enzymic capacity than the adult's due to 20% lower total chitinase and 23% lower total lipase activities. These results suggest that juvenile western sandpipers may process food differently from adults and/or have a lower-quality diet.
...
PMID:Digestive organ sizes and enzyme activities of refueling western sandpipers (Calidris mauri): contrasting effects of season and age. 1588 90

Eighty-six Nocardia strains isolated from clinical samples in Belgium were identified by 16S rRNA gene sequencing. Eighty-three (96%) strains belonged to only six Nocardia species: N. farcinica (38 [44%]), N. nova (19 [22%]), N. cyriacigeorgica (13 [15%]), N. brasiliensis (6 [6.9%]), N. abscessus (5 [5.8%]), and N. paucivorans (2 [2.3%]). A gallery of nine conventional and enzymatic tests was developed for the rapid identification of the most common species isolated during this survey. Pyrrolidonyl aminopeptidase, gamma-glutamyl aminopeptidase, alpha-mannosidase, and alpha-glucosidase were found to be highly discriminating and could be used to develop an identification scheme.
...
PMID:Distribution of nocardia species in clinical samples and their routine rapid identification in the laboratory. 1595 75

Anuran metamorphosis is one of the most spectacular processes in nature. Metamorphosis entails morphological transformations and extensive changes in feeding habits, such as transforming from an herbivore to a carnivore. This phenomenon is especially sensitive to environmental cues. We studied the phenotypic plasticity of intestinal morphology and enzyme activity in tadpoles of the Chilean giant frog Caudiverbera caudiverbera. We tested the effects of diet and temperature using a factorial design, which included a control of nontreated individuals. There was no significant effect of diet treatment (i.e., low- vs. high-quality diet) on any of the measured variables, including external morphology. We found significant effects of temperature on morphological traits. Temperature treatment also had significant effects on aminopeptidase-N and maltase activity. Both enzymes exhibited complex interactions with temperature along the intestine. Gut size varied significantly among temperatures, with intestines from warm-treated individuals smaller than the intestines from control and cold-treated tadpoles. Our findings suggest that phenotypic plasticity of intestinal morphology and physiology exists in larvae of this species, at least in response to temperature. However, we did not detect clear effects of diet or temperature on the timing of metamorphosis.
...
PMID:Digestive plasticity in tadpoles of the Chilean giant frog (Caudiverbera caudiverbera): factorial effects of diet and temperature. 1692 38

Many studies dealing with trinitrobenzene sulfonic acid (TNBS) colitis in rats have been carried out referring only to the colon. In humans, ulcerative colitis (UC) can extend a variable distance into the terminal ileum in a phenomenon known as backwash ileitis (BWI). The aim of this study was therefore to examine the effect of TNBS-induced colitis on different aspects of the rat ileum and jejunum. We hypothesized that TNBS administration would lead to a systemic influence on the small intestine. Rats were induced colitis by administration of 0.25 ml of 2,4,6-trinitrobenzene sulfonic acid and 72 h after colitis induction animals were sacrificed. Segments were taken of the colon, ileum and jejunum. In addition to mucin mRNA expression, morphological changes were observed in the jejunum and ileum. We examined the mRNA expression and biochemical activity of brush border enzyme, sucrase iso-maltase and aminopeptidase, in all three segments. The villous surface area of colitis-induced rats was smaller in jejunum and ileum compared to control. In the jejunum of TNBS-induced rats, goblet-cell volume increased and their density decreased. The relative amount of MUC2 mRNA decreased in the jejunum, ileum and colon of colitis rat. However, MUC3 mRNA expression increased in the ileum and colon of these rats. Sucrase isomaltase expression and activity decreased in the ileum of TNBS-induced rats, while aminopeptidase activity was lower in the jejunum. These observations suggest that intrarectal administration of TNBS to rats influences not only their colon and terminal ileum, but also the proximal ileum and jejunum. Involvement of the ileum and jejunum in TNBS-induced colitis may be related to the systemic reaction of the immune system and mucosa to colitis.
...
PMID:Mucosal function in rat jejunum and ileum is altered by induction of colitis. 1696 28


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---