Digestibility of the hydrogenated derivative of an isomaltooligosaccharide mixture by rats.

The digestibility of the hydrogenated derivative of an isomaltooligosaccharide mixture (IMO-H) was investigated. In an in vitro experiment, the digestibility of IMO-H was examined by models of the digestive system. IMO-H was resistant to two types of alpha-amylase and to artificial gastric juice. Enzymes in the rat small intestinal mucosa hydrolyzed tri-, tetra- and higher saccharide alcohols to disaccharide alcohol, removing successive glucose units from the non-reducing ends of the chains. The hydrolysis ratio for IMO-H was intermediate between the values for maltose and maltitol. In an in vivo study, growing rats were fed on an experimental diet containing IMO-H, maltitol, or hydrogenated palatinose in the range from 5% to 20%. The growth parameters of the rats fed on the test sugar show that the availability of IMO-H was about 1.2 to 1.25 times that of maltitol or hydrogenated palatinose.     

Stopped-flow investigation of the reaction between vitamin E radical and vitamin C in solution

Kinetic study of the reaction between vitamin E radical and vitamin C has been performed. The rates of reaction of vitamin C (ascorbic acid 1, 6-0-stearyl ascorbic acid 2, and 2,6-O-dipalmitoyl ascorbic acid 3) with vitamin E radical (5,7-diisopropyl-tocopheroxyl) in benzene-ethanol (2:1, v/v) solution have been determined spectrophotometrically, using stopped-flow technique. The second-order rate constants obtained are 549 +/- 30 M-1s-1 for 1, 626 +/- 53 M-1s-1 for 2, and 4.84 +/- 1.41 M-1s-1 for 3 at 25.0 degrees C. The result shows that the ascorbic acid ester 2 having a long-alkyl-chain at 6-position is 1.14 times as reactive as the ascorbic acid 1, whereas the ascorbic acid ester 3 substituted at 2-position is only 0.01 times as reactive as the ascorbic acid 1.     

Restriction map and alpha-amylase activity variation among Drosophila mutation accumulation lines

The specific activities of alpha-amylase were measured for two sets of mutation accumulation lines, each set having originated from a different lethal-carrying second chromosome and SM1(Cy) chromosome and having been maintained by a balanced lethal system for about 300 generations. Significant variation was found to have accumulated among lines of both sets. Because of dysgenic crosses in the early generations of mutation accumulation, insertions or deletions of transposable elements in the Amy gene region were suspected of being the cause of this variation. In order to test this possibility, the structural changes in the 14 kb region of these chromosomes that includes the structural genes for alpha-amylase were investigated by restriction map analysis. We found that most part of the activity variation is due to replacements of a chromosomal region of SM1(Cy), including the structural genes for alpha-amylase, by the corresponding regions of the lethal chromosomes. One line also contained an insertion in this region but this line has an intermediate activity value. Thus, insertions of transposable elements into the Amy gene region were not found to be responsible for the new variation observed in alpha-amylase activity. If we remove those lines with structural changes from the analysis, the genetic variance of alpha-amylase specific activity among lines becomes non-significant in both sets of chromosomes.     

Construction and expression of human aldolase A and B expression plasmids in Escherichia coli host

E. coli expression plasmids for human aldolases A and B (EC 4.1.2.13) have been constructed from the pIN-III expression vector and their cDNAs, and expressed in E. coli strain JM83. Enzymatically active forms of human aldolase have been generated in the cells when transfected with either pHAA47, a human aldolase A expression plasmid, or pHAB 141, a human aldolase B expression plasmid. These enzymes are indistinguishable from authentic enzymes with respect to molecular size, amino acid sequences at the NH2- and COOH-terminal regions, the Km for substrate, fructose 1,6-bisphosphate and the activity ratio of fructose 1,6-bisphosphate/fructose 1-phosphate (FDP/F1P), although net electric charge and the Km for FDP of synthetic aldolase B differed from those for a previously reported human liver aldolase B. In addition, both the expressed aldolases A and B complement the temperature-sensitive phenotype of the aldolase mutant of E. coli h8. These data argue that the expressed aldolases are structurally and functionally similar to the authentic human aldolases, and would provide a system for analysis of the structure-function relationship of human aldolases A and B.     

Effects of auxin and gibberellin on conidial germination and elongation of young hyphae in a cyclic 3′:5′ adenosine monophosphate-dependent protein kinase mutant of Neurospora crassa

The possibility that plant growth regulators may relate to a cyclic 3:5 adenosine monophosphate (cAMP)-dependent protein kinase through the control of cAMP level in the conidial germination process of Neurospora crassa was examined using a cAPM-dependent protein kinase mutant (cpk mutant) which is thought to be cAMP-independent because of defect in the regulatory subunit of cAMP-dependent protein kinase. IAA, 2,4-D and GA₃ promoted conidial germination and elongation of young hyphae in the mutant as well as in the wild-type. The result suggests that the effects of auxin and gibberellin on germination and hyphal elongation are not mediated by cAMP.     

Transfer of Hessian fly resistance from rye to wheat via radiation-induced terminal and intercalary chromosomal translocations

Summary A new Hessian fly (Mayetiola destructor) resistance gene derived from Balbo rye and its transfer to hexaploid wheat via radiation-induced terminal and intercalary chromosomal translocations are described. Crosses between resistant Balbo rye and susceptible Suwon 92 wheat and between the F₁ amphidiploids and susceptible TAM 106 and Amigo wheats produced resistant BC₂F₃ lines that were identified by C-banding analysis as being 6RL telocentric addition lines. Comparative chromosomal analyses and resistance tests revealed that the resistance gene is located on the 6RL telocentric chromosome. X-irradiated pollen of 6RL addition plants was used to fertilize plants of susceptible wheats TAM 106, TAM 101, and Vona. After several generations of selection for resistance, new sublines were obtained that were homogeneous for resistance. Thirteen of these lines were analyzed by C-banding, and three different wheat-6RL chromosomal translocations (T) were identified. Wheat chromosomes involved in the translocations were 6B, 4B, and 4A. Almost the complete 6RL arm is present in T6BS · 6BL-6RL. Only the distal half of 6RL is present in T4BS · 4BL-6RL, which locates the resistance gene in the distal half of 6RL. Only a very small segment (ca 1.0 m) of the distal region of 6RL is present in an intercalary translocation (Ti) Ti4AS · 4AL-6RL-4AL. The 6RL segment is inserted in the intercalary region between the centromere of chromosome 4A and the large proximal C-band of 4AL. The break-points of the translocations are outside the region of the centromere, indicating that they were induced by the X-ray treatment. All three translocations are cytologically stable and can be used directly in wheat breeding programs.Cooperative investigations of the Kansas Agricultural Experiment Station, Departments of Entomology and Plant Pathology, the Wheat Genetics Resource Center, Kansas State University, and the US Department of Agriculture, Agricultural Research Service. Contribution No. 91-117-JDeceased     

Stopped-flow investigation of antioxidant activity of tocopherols. Finding of new tocopherol derivatives having higher antioxidant activity than alpha-tocopherol

Second-order rate constants, kappa s, for H-atom abstraction by phenoxyl radicals from five tocopherol (vitamin E) derivatives have been measured spectrophotometrically at 25.0 degrees C by the stopped-flow method, as a model reaction of tocopherols with unstable free radicals (LOO., LO., and HO.) in biological systems. Three new tocopherol derivatives with a five-membered heterocyclic ring were found to be 1.9-2.1 times more active than the alpha-tocopherol which has the highest antioxidant activity among natural tocopherols. The proton hyperfine splittings for the five tocopheroxyl radicals derived from these tocopherols by the reaction with phenoxyl were also determined by ESR measurements.