Inhibitory effect of voglibose and gymnemic acid on maltose absorption in vivo

AIM To determine whether diabetic care can be improved by combination of voglibose and gymnemic acid ( GA ), we compared the combinative and individual effects of voglibose and GA on maltose absorption in small intestine.METHODS The small intestine 30 cm long from 2 cm caudal ward Treitz's ligament of Wistar rat was used as an in situ loop, which was randomly perfused in recircular mode with maltose (10 mmol/L) with or without different dosages of voglibose and/or GA for an hour. To compare the time course, perfusion of 10 mmol/L maltose was repeated four times.Each time continued for 1 hour and separated by 30 minutes rinse. In the first time, lower dosages of GA (0.5g/ L) and/ or voglibose (2μmol/L) were contained except control.RESULTS Absorptive rate of maltose was the lowest in combinative group (P< 0.05, ANOVA),for example, the inhibition rate was about 37%during the first hour when 0.5g/L GA and 2μmol/L voglibose with 10mmol/L maltose were perfused in the loop. The onset time was shortened to 30 minutes and the effective duration was prolonged to 4 hours with the combination; therefore the total amount of maltose absorption during the effective duration was inhibited more significantly than that in the individual administration (P＜0.05, U test of Mann-Whitney). The effect of GA on absorptive barriers of the intestine played an important role in the combinative effects.CONCLUSION There are augmented effects of voglibose and GA. The management of diabetes mellitus can be improved by employing the combination.

Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine

AIM To compare the combinative andindividual effect of acarbose and gymnemic acid(GA) on maltose absorption and hydrolysis insmall intestine to determine whether nutrientcontrol in diabetic care can be improved bycombination of them.METHODS The absorption and hydrolysis ofmaltose were studied by cyclic perfusion ofintestinal loops in situ and motility of theintestine was recorded with the intestinal ring invitro using Wistar rats.RESULTS The total inhibitory rate of maltoseabsorption was improved by the combination ofGA (0.1 g/L 1.0 g/L) and acarbose(0.1 mmol/L 2.0 mmol/L) throughout theireffective duration (P＜0.05, U test of Mann-Whitney), although the improvement only couldbe seen at a Iow dosage during the first hour.With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3 h and the inhibitory effect onset of GA was fastened to 15min. GA suppressed the intestinal mobility with a good correlation (r-0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1 g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers.CONCLUSION There are augmented effects of acarbose and GA, which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination.

Effect of Maltose Concentration on Plant Regeneration of Anther Culture with Different Genotypes in Rice (<i>Oryza sativa </i>L.)

This study describes the impact of different concentrations of maltose on plant regeneration of anther culture for five genotypes of rice (Oryza sativa). N6 medium was used for calli induction, while N6 medium supplemented with different concentrations of maltose, 2.0 mg/L NAA and 0.5 mg/L kinase was used for plant regeneration. The result showed that during the initial stages of calli induction the anther cultures had varying rates of calli formation among genotypes, with the best frequency being observed for Dreami2/CaMsrB2-8-DH-1 with a calli frequency of 27.8%. Different genotypes of rice cultured in regeneration media showed varying plantlet regeneration on media supplemented with different concentrations of maltose, with low concentrations (0.04 g/L) leading to low frequency regeneration plantlet but high green plant production. Indeed, when Dreami2/CaMsrB2-8-DH-2 and Dreami2/CaMsrB2-8-DH-5 were cultivated under these conditions, 100% green plants were observed. Another genotype also showed a small rate of albino frequency in response to the lowest concentration of maltose, while increased maltose concentrations resulted in increased rates of albino plants. Overall, the results of this study should facilitate establishment of an efficient plant regeneration system from anther culture in rice.

Biosensor for maltose quantification and estimation of maltase activity

Abstract: The aim of this study was to create a laboratory model of an amperometric microbial biosensor for maltose quantification in the presence and absence of starch and to estimate the use of the model in the study of maltase activity of the culture-receptor. The biosensor for maltose was developed on the basis of a Clark-type oxygen electrode, coupled with a bioreceptor, which contained bacterial cells immobilized on the membrane. The determination of maltose concentration was based on measuring the rate of electrode current change in response to addition of the analyte. The detection limit of the biosensor was 1 μM maltose, a linear interval of standard curve was observed from 14 μM up to 1.9 mM of maltose. The microbial biosensor demonstrated good sensitivity to maltose, 36.02 nA (M-s)-1. Combination of bioreceptors on the basis of fungus and bacterium allowed of using the biosensor for quantification of maltose in the presence of starch. Changes in metabolism of the culture-receptor had an effect on the biosensor response. It indicated that the developed model was a tool of simple construction and easy-to-use in the study of maltase activity of the immobilized culture-receptor.

Optimization of Fermentation Conditions of <i>Bacillus thuringiensis</i>EC1 for Enhanced Methionine Production

Bacillus thuringiensis EC1, isolated from the fermented oil bean seed, Pentachletra macrophila Benthan, produced a methionine yield of 1.89 mg/ml. The influence of cultural conditions on methionine accumulation by B. thuringiensis EC1 showed that a 20% medium/fermenter volume ratio and a 5% inoculum size increased methionine yield. The carbon of choice was maltose and at 8% level stimulated methionine production. Among the nitrogen sources studied, ammonium sulphate was found to be the best and at 1% concentration produced a methionine yield of 2.56 mg/ml. All growth-promoting substances and their mixtures enhanced methionine accumulation by B. thuringiensis EC1. The effect of Vitamins on methionine production showed that riboflavin and thiamine HCl at 1.0 μg/ml yielded 2.49 mg/ml and 2.80 mg/ml methionine respectively. The influence of bivalent metals on methionine accumulation indicated that Zn2+ at all concentration stimulated methionine production. Mg2+ and Ba2+ at 0.1 μg/ml and 10.0 μg/ml respectively improved methionine yield. Optimizing the cultural conditions of B. thuringiensis EC1 in submerged medium gave a methionine yield of 3.18 mg/ml.

Sweet Potato Leaf Curl Virus: Coat Protein Gene Expression in <i>Escherichia coli</i>and Product Identification by Mass Spectrometry

Sweet potato is one of the first natural GMOs, genetically modified 8000 years ago by Agrobacterium rhizogenes as reported recently by Kyndt et al. A section of 10 kbp long DNA (Transferred- DNA or T-DNA) of the Ri (Root-inducing) plasmid was transferred to the plant genome by A. rhizo-genes and has been maintained in all 291 hexaploid sweet potato cultivars of the world. The maintenance in the sweet potato genome and expression of two T-DNA genes for tryptophan-2-monooxygenease (iaaM) and for indole-3-acetamide hydrolase (iaaH) are likely to be physiologically significant since these enzymes convert tryptophan to indole-3-acetic acid, a major plant growth hormone auxin. Sweet potato (Ipomoea batatas (L.) Lam) is ranked the third most important root crop after potato and cassava, and the seventh in global food crop production with more than 126 million metric tons. Although sweet potato originated in Central or South America, China currently produces over 86% of world production with 109 million metric tons. In the United States, North Carolina is the leading producer with 38.5% of the 2007 sweet potato production, followed by California, Mississippi, and Louisiana with 23%, 19%, and 15.9%, respectively. Leaf curl virus diseases have been reported in sweet potato throughout the world. One of the causal agents is Sweet potato leaf curl virus (SPLCV) belonging to the genus Begomovirus (family Geminiviridae). Although SPLCV does not cause symptoms on Beauregard, one of the most predominant sweet potato cultivars in the US, it can reduce the yield up to 26%. Serological detection of SPLCV is not currently available due to the difficulties in obtaining purified virions that can be used as antigen for antiserum production. In attempts to obtain the coat protein (CP) of SPLCV for antibody production, primers were designed to amplify the CP gene. This gene was cloned into the expression vector pMAL-c2E as a fusion protein with maltose-binding protein, and transformed into Escherichia coli strain XL1-Blue. After gene induction, a fusion protein of 72 kDa was purified by amylose affinity chromatography. The yield of the purified fusion protein was approximately 200 μg/liter of bacterial culture. Digestion with enterokinase cleaved the fusion protein into a 42.5 kDa maltosebinding protein and a 29.4 kDa protein. The latter protein was identified by mass spectrometry analysis as the coat protein of SPLCV based on the fact that the mass spectrometry elucidated the sequences corresponding to 37% of amino acid positions of the SPLCV coat protein.