Relation between intestinal alkaline phosphatase activity and brush border membrane transport of inorganic phosphate, D-glucose, and D-glucose-6-phosphate

Vitamin E amelioration of oxidative stress and low immunity induced by high-lipid diets in hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu)

The experiment was conducted to investigate the effects of vitamin E (VE) on growth, oxidative stress and immunity for hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) fed high-lipid diet. Six groups of iso-protein (50.23%) and iso-lipidic high-lipid (15.36%) experimental diets were prepared by adding 0 (basic diet control), 0.01%, 0.02%, 0.03%, 0.04%, 0.05% α-tocopherol respectively in basic diet. Each treatment consisted of 3 replicates and 30 fish (10.20 ± 0.02 g) in each replicate for 8 weeks. The results showed that: 1) compared with the control group, the growth performance of grouper was not affected by the addition of VE in high-lipid diet, but the specific growth rate (SGR) in high VE dose (0.6%) group were significantly decreased compared with 0.02% and 0.03% groups. 2) Adding VE to high-lipid diet can alleviate the hepatic oxidative damage caused by high-lipid diet, and significantly improve the serum and liver antioxidant enzyme activity. 3) Compared with the control group, appropriate VE significantly increased the expression of liver anti-inflammatory factors TGF-β and IL10, and significantly decreased the expression of proinflammatory factors IL8 and IL6. In conclusion, adding appropriate amount of VE into high-lipid diet can improve antioxidant capacity and immunity of grouper, we speculated that VE may alleviate lipid peroxidation by improving antioxidant capacity to reduce the inflammatory response. In combination with the results of the current study, we recommend an additional dose of 0.02%-0.03% of α-tocopherol in this experiment under high-lipid conditions.

Holstein dairy cows with high phosphorus utilization efficiency fed a low phosphorous diet secreted less phosphorus with urine but more with milk and feces

The environmental pollution of phosphorus (P) from livestock farming is becoming increasingly problematic especially with regard to dwindling global P resources. Thus, a more sustainable handling of P resources, including improvements in P use efficiency and a reduction of P loss from farm animals, is necessary. Dairy cows may differ in milk P yield and P use efficiency despite receiving the same feed ration. The objective of this study was to elucidate inter-individual differences in P and closely linked nitrogen (N) excretions and the expression of P transport proteins in dairy cows with low and high P utilization efficiency. Twenty multiparous, late lactating German Holstein dairy cows were retrospectively assigned to either a high (HPeff; n = 10) or low (LPeff; n = 10) P utilization efficiency group. Cows were fed a diet low in P and crude protein (CP) content. During a 4-day balance study, feed intake, urine and fecal excretions, and milk yield were recorded to determine total P and N content in subsamples. Mammary gland, kidney and jejunal mucosa were sampled to analyze mRNA expressions of P transporters by real-time-PCR. A high milk P yield in HPeff cows strongly correlated with milk protein and milk N yield. HPeff cows excreted less urinary P, had a higher renal P reabsorption rate, and a higher renal sodium-P cotransporter 2 expression than LPeff cows. As HPeff cows channeled more P into milk, they mobilized more P from body reserves as indicated by their more negative P-balance. In addition, HPeff cows had higher fecal P excretion relative to ingested P, resulting in a lower apparent P digestibility. In conclusion, when fed a low P diet, HPeff cows channeled more endogenous P into milk and feces, which in the long-term, likely has adverse effects on animal health and the environment.

Hepatic and gastroprotective activity of Serjania marginata leaf aqueous extract in Nile tilapia (Oreochromis niloticus)

The aim of this study was to assess the leaf aqueous extract composition of Serjania marginata and the effects of its inclusion on the diet of Nile tilapia (Oreochromis niloticus), with respect to the activity of digestive enzymes and enzymes associated with the metabolism of the liver and intestine and liver histopathology. Fish (initial mean weight, 54.36 ± 17.04 g) were divided into groups: fasting (without feeding), control (commercial feed), and treatment (commercial feed with leaf aqueous extract of Serjania marginata), and in each aquarium, there were five individuals and the fish fed ad libitum for 15 days. Treatment fish had ingested on average 224.3 mg of extract/kg of fish/day. In the extract analysis by mass spectrometry, quercitrin, isoquercitrin, A-type proanthocyanidin trimer, and quinic acid were identified. In the enzymatic activity, fish from the treatment group showed higher level of alkaline phosphatase, while the hepatotoxic markers (AST and ALT) and levels of lipase, amylase, and nonspecific protease did not differ (p > 0.05). In liver histopathological analysis, it was observed that fish from the treatment showed normal structure, while abnormalities were associated with control (fibrosis, loss of cordonal architecture, vacuolated hepatocytes with nucleus displaced to the periphery) and fasting (reduction in hepatocyte size and sinusoidal space). The intestine histopathology evidenced that the extract favored the development of goblet cells and intestinal fold height. The results indicated that the leaf aqueous extract of S. marginata assists in the structural maintenance of the liver and intestine and stimulates intestinal alkaline phosphatase production in Nile tilapia, suggesting that the identified compounds act on the liver and intestine, showing hepatoprotective effects and stimulating intestinal digestion.

Acid and alkaline phosphatase localization in the digestive tract mucosa of the Hemisorubim platyrhynchos

This cytochemical study investigated the acid and alkaline phosphatase of the digestive tract of Hemisorubim platyrhynchos. Acid phosphatase was detected in the lining epithelium throughout the digestive tract, whereas alkaline phosphatase was only observed in the intestine. In the esophagus, an acid phosphatase reaction occurred in the apical cytoplasm of the epithelial cells and was related to epithelial protection and freeing of superficial cells for sloughing. Similar results were also observed in epithelial cells of gastric epithelium. In the gastric glands, acid phosphatase occurred in lysosomes of the oxynticopeptic cells acting in the macromolecule degradation for use as an energy source, whereas in the vesiculotubular system, its presence could be related to secretion processes. Furthermore, acid phosphatase in the intestine occurred in microvilli and lysosomes of the enterocytes and was correlated to absorption and intracellular digestion. However, no difference was reported among the regions of the intestine. However, alkaline phosphatase reaction revealed a large number of reaction dots in the anterior intestine, with the number decreasing toward the posterior intestine. This enzyme has been related to several functions, highlighting its role in the nutrient absorption primarily in the anterior intestine but also being essential in pH regulation because this is a carnivorous species with many gastric glands with secretions that could damage the intestine.

The Secretion and Action of Brush Border Enzymes in the Mammalian Small Intestine

Microvilli are conventionally regarded as an extension of the small intestinal absorptive surface, but they are also, as latterly discovered, a launching pad for brush border digestive enzymes. Recent work has demonstrated that motor elements of the microvillus cytoskeleton operate to displace the apical membrane toward the apex of the microvillus, where it vesiculates and is shed into the periapical space. Catalytically active brush border digestive enzymes remain incorporated within the membranes of these vesicles, which shifts the site of BB digestion from the surface of the enterocyte to the periapical space. This process enables nutrient hydrolysis to occur adjacent to the membrane in a pre-absorptive step. The characterization of BB digestive enzymes is influenced by the way in which these enzymes are anchored to the apical membranes of microvilli, their subsequent shedding in membrane vesicles, and their differing susceptibilities to cleavage from the component membranes. In addition, the presence of active intracellular components of these enzymes complicates their quantitative assay and the elucidation of their dynamics. This review summarizes the ontogeny and regulation of BB digestive enzymes and what is known of their kinetics and their action in the peripheral and axial regions of the small intestinal lumen.

Morphological and histochemical study of intestine in wild and reared European eel (Anguilla anguilla L.)

Diet-related differences between the ratio of intestine length to body size and the enzymatic activity in the intestinal tract of wild and reared European eel (Anguilla anguilla L.) were studied. Compared with reared eel, wild eel showed significantly shorter relative intestine length. For the purpose of histochemical examination, different parts (anterior, middle and posterior) of intestine proper were used. Activities of non-specific esterase, alkaline and acid phosphatase, and aminopeptidase were examined in each segment. All enzymes were present in the intestines of both wild and reared European eel. Fish from both groups showed similar enzyme distribution within the enterocytes, but distribution and intensity of enzyme activity along the intestine vary depending on the group. Generally, reared European eel showed highest enzymatic activity and wider distribution of enzymes throughout all parts of the intestine. These results suggest that different diets could be one of the reasons for observed changes.

Histochemical analyses of digestive enzymes in the intestine of adult large-scaled gurnard (lepidotrigla cavillone, lacepède, 1801)

Localization and activity levels of the following digestive enzymes in the intestine of free-living large-scaled gurnard were determined: non-specific esterase, alkaline and acid phosphatase as well as aminopeptidase. Enzymatic activity of the four enzymes was confirmed in all intestine parts but with different distribution through the enterocytes and varying in diverse intensity according to intestine part. This research is part of a broader research project on the biology of economically important fish from the Adriatic Sea. Our study reveals that in the large-scaled gurnard, the middle and posterior intestinal segments play the major role in digestion and absorption of proteins, whereas all parts of the intestine participate in lipid absorption and intracellular digestion. The high protein and lipid content in the diet of the large-scaled gurnard is most likely responsible for high activities of esterase, alkaline phosphatase and aminopeptidase, as they are involved in digestion and absorption of proteins and lipids.

Mammalian intestinal alkaline phosphatase acts as highly active exopolyphosphatase

Recent results revealed that inorganic polyphosphates (polyP), being energy-rich linear polymers of orthophosphate residues known from bacteria and yeast, also exist in higher eukaryotes. However, the enzymatic basis of their metabolism especially in mammalian cells is still uncertain. Here we demonstrate for the first time that alkaline phosphatase from calf intestine (CIAP) is able to cleave polyP molecules up to a chain length of about 800. The enzyme acts as an exopolyphosphatase degrading polyP in a processive manner. The pH optimum is in the alkaline range. Divalent cations are not required for catalytic activity but inhibit the degradation of polyP. The rate of hydrolysis of short-chain polyP by CIAP is comparable to that of the standard alkaline phosphatase (AP) substrate p-nitrophenyl phosphate. The specific activity of the enzyme decreases with increasing chain length of the polymer both in the alkaline and in the neutral pH range. The K(m) of the enzyme also decreases with increasing chain length. The mammalian tissue non-specific isoform of AP was not able to hydrolyze polyP under the conditions applied while the placental-type AP and the bacterial (Escherichia coli) AP displayed polyP-degrading activity.

Distribution and properties of rat intestinal alkaline phosphatase isoenzymes

The ALP activities and properties of rat intestine cut into 20 segments were examined, and we were able to demonstrate that the ALP activity of upper intestine is high compared to that of lower intestine. This result coincided with those of other reports. However, we newly clarified that there is an ALP isoenzyme found in the lower intestine which can be inhibited by L-homoarginine. The molecular weight of the ALP isoenzyme was 136 kDa. In addition, it was clarified that there are several isoenzymes from upper to lower intestine. This study demonstrates that there exist isoenzymes, which are inhibited by L-HArg, in the intestine which are similar to the isoenzymes in the liver, bone and kidney.

Allotype immunoglobulin enhances alkaline phosphatase activity: implications for the inflammatory response

To understand the interactions among components of the immune/inflammation response, we studied the effects of immunoglobulins on the phosphatase activity of alkaline phosphatase in vitro. Bovine intestinal alkaline phosphatase was incubated with substrate in the presence of allotypic and xenotypic immunoglobulin. We found that bovine but not rabbit immunoglobulin enhanced the phosphatase activity of bovine intestinal alkaline phosphatase. Similarly, human but not bovine immunoglobulin G enhanced human placental alkaline phosphatase activity. By enhancing alkaline phosphatase activity, immunoglobulins bound to alkaline phosphatase may assist physiologic transport functions and enhance resolution of the inflammatory response. Further, in clinical conditions with high immunoglobulin concentrations, the serum alkaline phosphatase recorded may have spuriously high values.

Amino acid phosphatase activity of alkaline phosphatase. A possible role of protein phosphatase

Alkaline phosphatase (ALP) hydrolyzed phosvitin and amino acid phosphates demonstrating nonisotropy at different pH. Orthovanadate, a protein phosphatase inhibitor, more specifically inhibited the serine and tyrosine phosphatase activities of ALP than that of threonine phosphatase at concentrations > 0.1 mM or 0.01 mM, respectively. Calyculin A and okadaic acid at increased concentrations increased ALP amino acid phosphatase activity. Bisphosphonates, such as disodium-1-hydroxy-1-aminopropylidine-1,1-diphosphonate (APD) and ethane-1-hydroxy-1,1-diphosphonate (HEBP), at increased concentrations, inhibited ALP amino acid phosphatase activity. These results suggest that ALP may function as a protein phosphatase. In terms of protein kinase inhibitors, N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide, N-(6-aminoheyxl)-5-chloro-1-naphthalenesulfomide hydrochloride and 4',5,7-trihydroxyisoflavone had little effect on ALP amino acid phosphatase activity. Staurosporine slightly enhanced ALP serine and threonine phosphatase activities at a concentration of 0.1 mM. These results suggest that protein phosphatase activity does not depend on the protein kinase activity of ALP, since duality between the former and the latter is not supported. ALP may function less as a protein kinase than as a protein phosphatase. The coupling mechanism of phosphate dynamics may be regulated indirectly.

Alkaline phosphatase from Echinococcus multilocularis: purification and characterization

1. Kinetic and physical parameters of purified alkaline phosphatase from Echinococcus multilocularis metacestodes, livers of infected gerbils and control animals were determined. 2. Km value for p-nitrophenyl phosphate was about 0.05 +/- 0.02 mM for the three enzymes. 3. Vmax values were 357 +/- 67 nmol/min/mg proteins for metacestode enzyme, and 6.7 +/- 1.1 and 6.7 +/- 0.8 nmol/min/mg proteins for liver enzyme of infected and control animals, respectively. 4. Mr and pI were different for the parasite and hepatic enzyme. 5. The parasite enzyme was less sensitive to the elevation of temperature than hepatic enzyme. 6. The isatin inhibition was a competitive inhibition type for parasite and uncompetitive type for host liver enzyme.

The human alkaline phosphatases: what we know and what we don't know

A review of the human alkaline phosphatases dealing specifically with (1) the gene loci, (2) characterization and discrimination of the various enzymes, (3) polymorphism at the enzyme level, (4) cDNA and gene structures, (5) membrane binding, (6) the carbohydrate moieties, (7) hypophosphatasia, (8) alkaline phosphatases in malignancies, (9) function.