Biochemical analysis of the microvillose membranes of the small intestine mucosa of dogs after levorin administration

The effect of oral levorin used for a prolonged period of time on the lipid composition and activity of alkaline phosphatase and invertase of the microvilli membranes of the small intestinal enterocytes of old dogs was studied. Higher ratios of cholesterol/phospholipids in the membranes and inactivation of alkaline phosphatase and invertase were noted in the old dogs as compared to the young ones. Exposure of the old dogs to levorin had a significant effect on the microvilli membranes of the intestinal epithelial cells. It was evident from a lower ratio of cholesterol/phospholipids in the membranes and stimulation of the alkaline phosphatase activity. It is supposed that the changes in the state of the microvilli membranes of the small intestinal mucosa due to levorin play a definite role in the mechanism of its hypercholesterolemic action.     

Influence of high temperature on the enzyme activity of the small intestine in thyroidectomized rats]

It was revealed in acute experiments that exposure to high temperature changed the invertase, dipeptidase, lipolytic and alkaline phosphatase activity of the small intestinal mucosa in rats. The direction of these changes and their degree differed in the thyroidectomized and sham-operated animals. It is suggested that the thyroid hormones took part in the reaction of the fermentative systems of the small intestine to the action of the thermal factor.     

Influence of age on duodenal brush border membrane and specific activities of brush border membrane enzymes in Wistar rats.

To examine age-related changes in the morphology of intestinal brush border membrane (BBM; microvilli) and specific activities of intestinal BBM enzymes including alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (gamma-GT), and disacchridase, four groups of Wistar rats were sacrificed at 2.5 wk, 5 wk, 5 mon and 23 mon. In an electron microscopic examination, morphologically a less dense BBM structure in the duodenum of rats aged 23 mon was observed than that of rats aged 5 mon. Specific activity of ALP in the duodenum from 5-mon-old rats was significantly higher than from rats aged 2.5 wk and 23 mon. The mucosal tissues from 5-wk-old rats had significantly higher specific activity of gamma-GT than did tissues from the other ages. In sucrase and maltase specific activities, 5-mon-old rats had higher activities of these enzymes than other age groups, especially 2.5-wk- and 23-mon-old rats. There was also a significant effect of site on intestinal BBM enzyme activities in post-weanling rats. Regional gradients of ALP and gamma-GT along the entire small intestine (duodenum > jejunum > ileum) were remarkable. Disaccharidase activities peaked in the jejunum and declined toward both the duodenum and ileum. Taken together the result obtained here suggested that 5-mon-old rats had the most elevated intestinal function. This result also strongly indicated that the structure of the intestinal BBM and development of intestinal BBM enzymes in Wistar rate were markedly influenced by age during the postnatal period.     

Stimulation of maize invertase activity following infection by Ustilago maydis

The effect of U. maydis infection on the invertase activity of maize leaves has been studied. Infection causes a specific stimulation of an acid invertase in soluble and pellet fractions of homogenized tissue. Invertase activity is stimulated within one day after infection, and is maintained at a high level until 10 days after infection, in contrast to the progressive decline in activity with age, in healthy leaves. Analyses of soluble extracts by gel electrophoresis suggest that the invertase showing this increase is derived from the host and not the pathogen.     

Effect of heat and cold on the amylolytic and invertase activity of the small intestine of growing rats]

Acute experiments were conducted on ratlings; it was shown that the action of heat (40-41 degrees C), cold (5-6 degrees C), and ACTH injections (4 units per 100 g of body weight) during the first week after birth led to a sharp reduction of the total (alpha-gamma-conditioned) amylolytic and invertase activity of the homogenates and of the portions of the small intestine (turned inside out) of the growing rats. This depressed condition of the intestinal function was revealed directly after the arrest of the action of the unfavourable factors (7-day rats) and persisted for the subsequent two weeks of the animal life.     

Isoforms of trehalase and invertase of Fusarium oxysporum

Enzymatic assays and native PAGE were used to study trehalase and invertase activities, depending on culture age and different sugar conditions, in cell-free extracts, culture filtrates and ribosomal wash of Fusarium oxysporum. The activity of invertase preceded that of trehalase; in the exponential phase of growth, mainly invertase activity was produced, whereas trehalase activity was high in the stationary phase. In this last phase of growth, the activity of intracellular trehalase was repressed by monosaccharides, whereas disaccharides, especially lactose and starch, enhanced the activity of intracellular and extracellular trehalase. However, invertase activity was not repressed under these conditions and had the maximal activity in the presence of saccharose. Intracellular trehalase appeared in a single, high-molecular weight (120 kDa) form, whereas the extracellular enzyme appeared in a single, low-molecular weight (60 kDa) form. The activity pattern of invertase isoforms indicated the occurrence of three forms of intracellular enzyme with the main activity band at 120 kDa and two isoforms of extracellular enzyme. In the ribosomal wash, high-molecular weight isoforms of both trehalase and invertase were identified. A possible role of trehalase and invertase in carbohydrate metabolism of fungal pathogens is also discussed.     

Effect on lysosomes of invertase endocytosed by rat-liver

The intracellular localization of invertase endocytosed by rat liver was investigated by analytical centrifugation in sucrose and Percoll gradients of mitochondrial fractions originating from rats killed 15 h after injection. After isopycnic centrifugation in a sucrose gradient, invertase is located in higher density zones than acid hydrolases. The difference between the distribution of invertase and that of acid hydrolases increases with the amount of invertase injected. When the invertase dose is sufficiently high, a change of lysosomal enzyme distribution is clearly visible. It consists in the shift of a proportion of these enzymes to higher density regions where invertase is located. The proportion of hydrolase activity affected by invertase is different for each enzyme measured; it is the least pronounced for acid phosphatase, and most for acid deoxyribonuclease and arylsulfatase. A pretreatment of the rat with Triton WR 1339 considerably decreases the equilibrium density of structures bearing invertase. Nevertheless invertase distribution is quite distinct from that of the bulk of lysosomal enzymes that are recovered in lower density zones of the gradient; on the other hand the invertase injection to rats treated with Triton WR 1339 causes a spreading of the acid hydrolase distribution towards higher density zones. The distribution of acid hydrolases and invertase in a Percoll gradient depends on the sucrose concentration of the solvent. It is shifted towards higher densities when the sucrose concentration increases. The phenomenon is more important for invertase. These results are best explained by supposing that invertase accumulates in a distinct population of lysosomes that can be individualized as a result of the density increase they are subjected to by the invertase they accumulate. It is proposed that these lysosomes mainly originate from non-parenchymal cells of the liver.     

Mucosal inflammation in a genetic model of spontaneous type I diabetes mellitus

The BioBreeding (BB) rat provides a model of spontaneous type I diabetes mellitus that closely resembles the human disease. Diabetes-prone BB rats demonstrate increased intestinal permeability prior to the development of insulinitis. Studies suggest that alterations in intestinal permeability can lead to increased intestinal inflammatory activity. Diabetes-prone (BBdp) and diabetes-resistant (BBdr) BB rats were examined at 45 days and at >70 days of age following the development of clinical disease (BBd). In separate experiments, tissue was assayed for myeloperoxidase (MPO) or fixed for histological assessment and immunohistochemistry. Blood was obtained for leukocyte MPO measurements and morphological assessment of circulating leukocytes. MPO activity was significantly elevated in the distal small intestine of 45-day-old BBdp rats. In contrast, at >70 days of age, MPO activity was significantly increased throughout the small intestine of BBd and non-diabetic BBdp rats. Subsequently, all measurements were performed in >70-day-old rats. An increase in inflammatory infiltrate was noted in the distal small intestine of BBd rats by light microscopy. Infiltrating cells were identified as bands (a maturing cell type of the neutrophil lineage) and mature neutrophils. The findings suggest diabetes susceptibility is associated with an increase in intestinal inflammatory activity.     

Sex differences in spironolactone induction of rat intestinal and hepatic p-nitrophenol UDP-glucuronyltransferase

In the present study we analyzed the effect of spironolactone administration on hepatic and intestinal p-nitrophenol-UDP-glucuronyltransferase activity. We used microsomal preparations from male and female Wistar rats to establish whether or not this effect was sex dependent. Enzyme activity was measured in the presence of UDP-N-acetylglucosamine, a presumed physiological activator of the enzyme. Female but not male microsomes showed an increase in enzyme activity of both hepatic and intestinal tissue preparations in response to the inducer pretreatment. In addition, the inducer effect observed in female rats showed a tissue-related difference, since percent increase in the intestinal enzyme activity was greater than that in the liver (127 and 52%, respectively). These results suggest that factors regulating enzyme activity or mechanisms involved in the inducer effect of spironolactone could be different in the intestinal mucosa in comparison to the liver. A possible explanation of sex-related response to spironolactone administration was discussed.     

Effects of Carbon Source, Gibberellins and Ethylene on Wall-Bound Invertase Activity in Callus of Convolvulus arvensis

The growth rate of Convolvulus callus on a sucrose-containing medium appeared to be largely independent of the activity of cell wall invertase. The increase of this enzyme activity which occurs upon subculturing was unaffected within the first 24 h by the presence of the substrate sucrose. Neither substitution by glucose or fructose, nor complete deletion of the carbon source had any effect. Gibberellins apparently were not involved in the initiation and/or control of the increase of wall-bound invertase activity occurring upon subculturing. Exogenous ethylene was unable to mimick this effect of subculturing but when applied immediately after subculturing it had a synergistic effect on the increase of invertase. Inhibition occurred, however, when exposure to ethylene was delayed until after 24 h of incubation. These findings suggest a role of ethylene in the control of wall-bound invertase activity.     

Activity of gut invertase in phytophagous, saprophagous and carnivorous insects

The effect of hydrogen-ion concentration, temperature, substrate concentration, enzyme concentration and incubation period on invertase activity of Dactylosternum hydrophilioides, Catharsius molossus and Pheropsophus occipitalis has been studied. The optimum invertase activity was observed at pH 6.5, 6.8 and 6.0 and at temperatures 35, 38 and 37 degrees C in D. hydrophiliodes, C. molossus and P. occipitalis, respectively. With the increase in substrate (sucrose) concentration, an increase in invertase activity was recorded. For invertase activity estimation, 4% sucrose concentration was found suitable in these insects where an increase in enzyme concentration increases the invertase activity. The invertase activity also increases with lengthening of the incubation period but after some time it remains constant in the phytophagous, saprophagous and carnivorous insects. The activity of invertase in phytophagous, saprophagous and carnivorous insects shows their independent nature as regards the pH and temperature.     

Age-related changes in antioxidant enzyme activities in the small intestine and liver from Wistar rats.

The present study was designed to determine age-related changes in intestinal and hepatic antioxidant enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and glutathione-S-transferase (GST), and lipid peroxidation in male Wistar rats (n = 8) aged 2 wk, 2.5 mon, 5 mon, 10 mon, and 23 mon. In the small intestine, cytosolic SOD, GSH-PX activities and lipid peroxidation were not affected by age, but intestinal GST activity was noticeably enhanced as age increased. In particular, intestinal GST activity in 23 mon old rats was 3 times as strong as that in 2 wk old rats. In the liver, the activity of hepatic cytosolic SOD was not affected by age, whereas GSH-PX and GST activities in rats aged 10 mon and 23 mon were much stronger than those in rats aged 2 wk, 2.5 mon, and 5 mon. The increased lipid peroxidation in 2.5 mon and 5 mon old rats was observed when compared with that of other groups. It is therefore concluded from the results presented here that age greatly increases GST activity in the small intestinal mucosae and increasing GSH-PX, GST activities and lipid peroxidation in the liver from male Wistar rats.     

Origin of intestinal disaccharidases of Ascaris suum

Disaccharidases from the gut of Ascaris suum were investigated to determine whether they were synthesized by the worm or whether they were host enzymes adsorbed to the worms' intestinal cells. Alpha-d-glucoside glucohydrolase (maltase) (EC 3.2.1.20), Beta-d-fructofuranoside fructohydrolase (invertase) (EC 3.2.1.26) and 1-glucohydrolase (trehalase) (EC 3.2.1.28) from Ascaris were studied in both a membrane (brush border)-bound and solubilized form with regard to temperature stability and pH optima. Data collected were compared to similar data on hog intestinal enzymes. Worm maltase and trehalase were relatively heat labile, whereas the hog enzymes were more stable to heat inactivation. Worm invertase was heat stable in comparison to the hog enzyme. The pH optima for Ascaris maltase and invertase were different from those of hog disaccharidases, whereas the pH optimum for trehalase from both parasite and host were similar. Tissue homogenates of second-stage larvae contained measurable maltase, but not sucrase, or trehalase activity. Results suggested that Ascaris intestinal disaccharidases represent three distinct enzymes of parasite rather than host origin.     

Effect of ethanol on intestinal lipid absorption in the rat

The effect of ethanol infusion on intestinal lipid absorption was studied in rats with a duodenal cannula. Rats were infused with ethanol overnight and ethanol was included in a trioleoylglycerol emulsion infusion given for 3 hr the next day. These rats were compared to control animals infused with glucose (isocalorically). The ethanol-infused rats had a greatly impaired lipid absorptive capacity. The monoacylglycerol and free fatty acid contents in the intestinal lumen in the ethanol-infused rats were 4- and 7-fold greater, respectively, than controls. The inhibition of absorption was not due to an effect of ethanol on lipolytic activity. The lipase content of the ethanol-infused rats was greater than controls and the separate infusion of monoacylglycerol and fatty acids demonstrated impaired absorption of these end products of lipolysis as compared to controls. To observe if these changes were due to an effect of ethanol on the enterocyte brush border membrane, the membrane lipids were analyzed. The phosphatidylcholine, lysophosphatidylcholine, and phosphatidylethanolanine content was reduced but not the neutral lipids, sphingomyelin, or phosphatidylserine. The uptake of fatty acid into intestinal rings was also shown to be impaired by ethanol infusion. Lastly, the specific activity of the neutral lipids remaining in the intestinal lumen after [3H]glycerol-labeled trioleoylglycerol-infusion was similar to controls even though the mass was much greater. It is concluded that ethanol impairs neutral lipid absorption due to an effect on the enterocyte brush border membrane and by increasing the efflux of low specific activity lipid from the enterocyte back out into the intestinal lumen. A potential pathway for this efflux is the recently described increased porosity of the apical junctional complex in response to ethanol infusion.     

Localization of cloned invertase in Saccharomyces cerevisiae directed by the SUC2 and MFalpha1 signal sequences

Protein localization in Saccharomyces cerevisiae was studied with two plasmid systems used as a model: one containing the SUC2 structural gene fused with the MFalpha1 (alpha-factor) promoter and signal-sequence, the other containing the entire SUC2 gene. Special emphasis was placed on the effect of promoter/signal-sequence (SUC2 vs. MFalpha1) on the efficiency of invertase transport. The MFalpha 1 and SUC2 signal sequences were capable of transporting, respectively, 83% and 77% of cloned invertase out of the cytoplasm. However, the SUC2 promoter was easier to control since a six-fold enhancement of the transported invertase activity associated with derepression was achieved in response to a glucose concentration change from 10 to 2 g/L Cloning on a multicopy plasmid resulted in a four-fold increase in total specific invertase activity over the wild type yeast strain (which harbors a single copy of the SUC2 gene on the chromosome), whereas the chromosomal site was more efficient for invertase localization yielding over 90% of the invertase transported out of the cytoplasm. Transient experiments done with the SUC2 signal-sequence-containing plasmid showed that the specific invertase activity in the periplasmic space reached a maximum three hours after derepression, then decreased very slowly with an accompanying gradual increase in invertase activity in the growth medium.     

Novel genetic components controlling invertase production in Saccharomyces cerevisiae

Low levels of invertase (EC 3.2.1.26) activity were observed in most diploid strains of S. cerevisiae used in this work. There was no effect of mating type on invertase levels, and cell surface was not a limiting factor, because an increase in ploidy did not cause further decrease in specific invertase activity. Finally, some diploids showed the activity expected from the additive effects of different SUC genes, and haploid strains possessing two SUC genes expressed very variable invertase activities depending on the strain. This suggested the existence of one or more additional genes which control the levels of invertase. Genetic analysis of SUC5 strains provided evidence of the existence of a new gene, RPS5, which drastically reduced the specific invertase activity in strains possessing active SUC alleles. The recessive allele of this gene (rps5) allows expression of higher levels of invertase. We suggest that genes similar RPS5 are responsible for the low levels of invertase activity observed in diploid strains of S. cerevisiae.     

The effect of high temperature and hydrocortisone on amylolytic and invertase activities of the mucous membrane of the small intestine in early ontogenesis of rats]

In experiments on 16-19 day rats, studies have been made of the effect of 2-hour heat exposure (40-41 degrees ) and hydrocortizone injection (4 mg per 100 g of body weight) on gamma-amylolytic and invertase activities of homogenized ad inside-turned pieces of proximal, middle and distal parts of the small intestine. It was shown that thermal stress results in a sharp increase of the enzymic activities of homogenates and total pieces of proximal and middle parts of the intestine. In distal parts, the enzymic induction is less significant or even completely absent. Hydrocortizone injections evoke similar changes, although the latter are more evident. On the basis of the data obtained, it is suggested that the effect of thermal factor on the synthesis of intestinal enzymes is realized via the hormones of suprarenal cortex.     

川西高山林线交错带凋落叶分解初期转化酶特征

胞外酶对于有机质的降解具有重要的作用。在凋落物分解过程中,酶活性不仅受到凋落物种类或基质质量的影响,还受到环境因素的影响。转化酶催化蔗糖水解为葡萄糖和果糖,因此在凋落物分解早期,转化酶比降解难分解物质的酶具有更重要的作用。以川西高山林线交错带12种代表性凋落叶为研究对象,对林线交错带不同植被类型下的凋落叶转化酶活性以及物种和环境因子对转化酶活性的影响进行了研究。结果表明:同一植被类型下,12个物种转化酶活性具有极显著差异(P0.01)。物种、环境因子及其交互作用对转化酶活性有极显著的影响(P0.01)。初始纤维素含量与转化酶活性极显著正相关(P0.01)。初始木质素和总酚含量与转化酶活性极显著负相关(P0.01),能够共同解释转化酶活性变异的50.8%。不同植物生活型中,禾草类转化酶活性均为最高,这可能与禾草类较高的初始纤维素含量、较低的木质素和总酚含量有关。多元线性回归分析表明,凋落叶含水量能单独解释转化酶活性变量的62.1%,是环境因子中最重要的变量。从植被类型来看,大多数物种的转化酶活性在针叶林中均极显著高于高山草甸和灌丛(P0.01),这可能与针叶林中凋落叶的含水量最高且雪被最厚有关。历经一个雪被期分解后,凋落叶初始质量与环境因子的综合作用能够解释转化酶活性变异的79.1%,表明川西高山林线交错带凋落叶分解前期转化酶活性主要受初始木质素含量、总酚含量和含水量的调控。在全球气候变化情景下,凋落物水分含量的变化将会强烈的影响凋落叶分解前期的转化酶活性。