Isolation of Possible Intermediate of Chlorogenic Acid Biosynthesis in Sweet Potato Root Tissue

Thienodolin, a new plant growth-regulating substance, was isolated from the fermentation broth of a streptomycete strain identified as Streptomyces albogriseolus.

The active principle was extracted with ethyl acetate and purified by silica gel column chromatography and preparative HPLC. The substance showed growth promoting activity with 1.2 × 10^?6–1.2 × 10^?5 M treatment to rice seedlings, and inhibitory activity with 4.0 × 10^?5 M treatment.     

Changes in Acid-soluble Nucleotides in Cut-injured Sweet Potato Root Tissue

ATP and ADP increased in cut-injured sweet potato root tissue during the 3 to 6-hr incubation period, and showed the maximum for the 9 to 18-hr, and 6 to 9-hr incubation periods, respectively, then decreased. ATP was present in the highest amount among ATP, ADP and AMP throughout the 72-hr incubation period, while AMP was in the lowest. Total acid-soluble nucleotides increased gradually, and showed the peak content at the 12-hr incubation period, and decreased thereafter. Adenine mononucleotides such as ATP, ADP and AMP occupied about 40 to 65% of total acid-soluble nucleotides.     

Isolation of 1-O-trans-p-Coumaroyl-r{beta}-D-glucopyranose from Sweet Potato Roots and Examination of Its Role in Chlorogenic Acid Biosynthesis

1-O-trans-p-Coumaroyl-rß-D-glucopyranose (p-coumaroyl-D-glucose)was isolated from slices of sweet potato root which had beenincubated with trans-cinnamic acid. Pre-loaded trans-cinnamicacid efficiently trapped the radioactivity from L-[U-¹⁴C]-phenylalanineand reduced its incorporation into chlorogenic acid by 75% ofcontrol values in disks of sweet potato root. In the root diskssupplied with trans-[3-¹⁴C]-cinnamic acid, the radioactivitywas transferred first to trans-cinnamoyl- D-glucose, then top-coumaroyl-D-glucose, and subsequently to chlorogenic acidand isochlorogenic acid. These results support our earlier propositionthat p-coumaroyl-D-glucose is involved in the biosynthesis ofchlorogenic acid as an intermediate adjacent in the pathwayto trans-cinnamoyl-D-glucose in sweet potato roots. (Received April 11, 1988; Accepted August 9, 1988)     

Stimulation by Ethylene of Mitochondrial Development in Wounded Sweet Potato Root Tissue

Ethylene (about 100 µl per liter) markedly stimulatedincreases in respiratory, Cyt c oxidase and succinate dehydrogenaseactivities of the crude mitochondrial fraction as well as mitochondrialmembrane protein during aging of sliced sweet potato root tissue,indicating that it stimulated mitochondrial development in woundedtissue. It had such an effect even when slices were pre-agedin its absence for 1 day and thereafter aged in its presence.The mitochondrial inner membrane from slices aged in ethylene-containingair was denser than that from fresh slices, while the membranefrom slices aged in ethylene-free air was lighter. Chloramphenicolcompletely inhibited the increase in Cyt c oxidase activitywhether slices were aged in the presence or absence of ethylene.Cycloheximide did not inhibit the increase in slices aged inethylene-free air, but did by 50% in those aged in ethylene-containingair. ¹ This work was supported in part by a Grant-in-Aid (No. 411308)for Scientific Research from the Ministry of Education, Scienceand Culture, Japan. (Received April 4, 1981; Accepted July 7, 1981)     

Induction of Polysome Formation in Sweet Potato Root Tissue in Response to Wounding

We determined the effects of yolk water-soluble protein (YSP) on bone resorption. YSP potently suppressed osteoclastogenesis from bone marrow-derived precursor cells driven by tumor necrosis factor-α (TNF-α). YSP (200 μg/ml) abolished the formation of tartarate-resistant acid phosphatase (TRAP)-positive osteoclasts. Furthermore, TNF-α induced TRAP activity was greatly inhibited by YSP (100 μg/ml) treatment. Our results suggest that YSP has therapeutic potential for bone-erosive diseases.     

Mechanism of the Increase in Succinate Dehydrogenase Activity in Wounded Sweet Potato Root Tissue

The large subunit (mol wt: 65,000) of sweet potato succinatedehydrogenase was isolated by SDS-polyacrylamide gel electrophoresisof a succinate dehydrogenase preparation, which had been partiallypurified from root mitochondria by solubilizing the enzyme withEmulgen 810, DEAE-cellulose column chromatography, and polyacrylamidegel electrophoresis. Antibody to the purified large subunitwas produced in a rabbit, and the antiserum obtained was judgedto be specific to the large subunit based on the results ofdouble immunodiffusion tests and immunoelectrophoresis. Rocketimmunoelectrophoresis with the antiserum showed that the increasein succinate dehydrogenase activity during the ageing of sliced,sweet potato root tissue was due to an increase in the amountof enzyme protein. Both the increases in the activity of succinatedehydrogenase and in the amount of the large subunit proteinwere inhibited by cycloheximide or chloramphenicol. We proposethat synthesis of the large subunit of succinate dehydrogenaseon cytoplasmic ribosomes is controlled by a mitochondrial translationproduct(s). ¹ This work was supported in part by a research fund from TheIshida Foundation, Nagoya, Japan. (Received November 28, 1981; Accepted February 17, 1982)     

Mechanism of the Increase in Catalase Activity through Microbody Development in Wounded Sweet Potato Root Tissue

An increase in catalase activity accompanied by microbody developmentin wounded sweet potato root tissue was investigated with aspecific antibody against sweet potato catalase. The increasewas completely inhibited by cycloheximide. Analysis with singleradial immunodiffusion method showed that protein immunoprecipitatedby the antibody increased in wounded tissue, indicating theinvolvement of de novo synthesis of catalase protein in theactivity-increase. The activity-increase was, however, moreremarkable than the increase in immunoreactive protein and thisresults in an increase in specific catalase activity in woundedtissue, indicating the presence in intact tissue of an inertor less active protein, immunologically analogous to catalase.Actually, immunological analysis showed the presence in intacttissue of an immunoreactive protein which differed from activecatalase protein in the mobility on a polyacrylamide gel andprobably also in the molecular weight of subunit. The immunoreactiveprotein seemed to exist in a significant amount outside themicrobodies in intact tissue cells. Thus, there is a possibilitythat the increase in catalase activity in wounded tissue ispartly due to activation of the immunoreactive protein. (Received October 16, 1982; Accepted February 24, 1983)     

Increase of Mitochondrial Fraction in Sweet Potato Root Tissue after Wounding or Infection with Ceratocystis fimbriata

The acid-insoluble nitrogen content, lipid content, and cytochrome oxidase activity in the mitochondrial fraction are found to increase during incubation of slices of sweet potato (Ipomoea batatas) root tissue. These increases appear to be related to an increase in the number of the mitochondrial particles. The increase in the mitochondrial fraction is not accompanied by an increase in cell number. The nitrogen content in the mitochondrial fraction increases prior to the changes in the activity of cytochrome oxidase and lipid content. The increase in the numbers of the mitochondrial particles lags behind the increase in the cytochrome oxidase activity. Such findings are also found in the tissue infected by Ceratocystis fimbriata.     

Isolation of Dehydro-ipomeamarone,a New Sesqui-terpenoid from the Black-rot Fungus Infected Sweet Potato Root Tissue and Its Relation to the Biosynthesis of Ipomeamarone

α_s1-Casein was dissolved in 50 mm cacodylate-HCl-70 mm KC1 buffer containing 0.02% of sodium azide (pH 7.1), and the size and shape of α_s1-caseins in the absence and presence of calcium ions were observed with the electron microscope. In the absence of calcium ions, most α_s1-caseins existed as spherical particles of which the smallest diameter was 5~6 nm. The particles were polymerized into bent chains by adding 3 mm calcium. It seemed that the smallest particles were the polymerizing units. The mean length of α_s1-casein in the absence of calcium was 8.7 nm, and it increased as the calcium concentration increased. From these results, it was speculated that α_s1-casein in the absence of calcium had one binding site and the calcium-induced conformational changes produced a second binding site. The probability distributions were calculated with the above speculation, and compared with the frequency distributions obtained from electron micrographs. It was suggested from the comparisons that the second binding site produced in α_s1-casein might be responsible for the calcium-induced aggregation.     

Effect of Ethylene on the Increase in Catalase Activity through Microbody Development in Wounded Sweet Potato Root Tissue

Catalase activity increases when slices of sweet potato roottissue are incubated in air. The increase is due to de novosynthesis of the enzyme protein and probably also to activationof a precursor protein [Esaka et al. (1983) Plant & CellPhysiol. 24: 615]. The activity-increase was partly depressedwhen tissue slices were incubated in ethylenecontaining air,while the immunologically determined amount of catalase proteindid not increase, rather it decreased, under the same conditions.We propose that ethylene inhibits the de novo synthesis of catalaseprotein but not the activation of precursor protein. Catalasefrom tissue slices incubated in ethylene-containing air migratedfaster on a polyacrylamide gel than that from intact tissueor tissue slices incubated in air. When either polyacrylamideor an SDS-polyacrylamide gel applied with crude extract fromtissue slices incubated in ethylene-containing air underwentimmunological blotting, the blots were much fainter than thosefor intact tissue. In addition, microbody membrane fractionfrom incubated tissue slices contained a significant amountof catalase which was sedimented at the bottom of a sucrosedensity gradient (20–70%) and was not solubilized by highconcentrations of lubrol PX. The fraction showed an exceptionallyhigh catalase activity per unit amount of immunoreactive proteinto anti-catalase antibody. We propose that ethylene causes somemodification of catalase protein which facilitates the formationof aggregates or cores. ¹Present address: Laboratory of Food Technology, Faculty ofApplied Biological Science, Hiroshima University, Fukuyama,Hiroshima 720, Japan. ²Present address: Terumo Co. Ltd., Omiya, Fujinomiya, Shizuoka418, Japan. (Received October 16, 1982; Accepted February 24, 1983)     

The contribution of taste bud populations to bitter avoidance in mouse strains differentially sensitive to sucrose octa-acetate and quinine

Mice of the SWR/J (SW) strain avoid orally delivered sucrose octa-acetate (SOA), whereas the mice of the C3HeB/FeJ (C3) strain are insensitive to SOA. Mice of both strains and of a congenic strain (C3.SW) that shares more than 99% of the C3 genome, were tested in a taste-salient brief-access taste test for responses to SOA and quinine hydrochloride, before and after transection of the glossopharyngeal or chorda tympani nerve, or sham surgery. Prior to surgery, congenic SOA tasters (C3.SW(T)) were phenotypically identical to the SW strain in avoidance of SOA, but showed a greater reduction in sensitivity after nerve transection. For quinine avoidance, which is thought to be a polygenic trait, SW mice showed the greatest sensitivity to quinine, C3 the least and C3.SW(T) mice were different from both parental strains, showing intermediate sensitivity. Nerve transections had only a moderate effect on quinine sensitivity, suggesting that both anterior and posterior taste bud fields contribute to behavioral quinine avoidance. These findings are discussed with regard to the distribution in the oral cavity of putative taste receptors for quinine and SOA and the peripheral organization of bitter taste.     

Top-Down Control of Sweet and Bitter Taste in the Mammalian Brain

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Different Intracellular Localization of Two Cytochrome P-450 Systems, Ipomeamarone 15-Hydroxylase and Cinnamic Acid 4-Hydroxylase, in Sweet Potato Root Tissue Infected with Ceratocystis fimbriata

Ipomeamarone 15-hydroxylase activity was mainly recovered inthe pellet fraction between centrifugations at 10,000 and 100,000?gfrom a crude extract of Ceratocystis fimbriata-infected sweetpotato root tissue, whereas cinnamic acid 4-hydroxylase activitywas found between centrifugations at 300 and 10,000?g. Whenparticles in the crude extract were fractionated by sucrosedensity gradient centrifugation, the rough-surfaced microsomeswere distributed over a wide density range from 1.09 to 1.14g cm^–3, judging from the distributions of protein, RNAand NADPH-cytochrome c reductase activity. Phosphorylcholine-glyceridetransferase activity was only in the lighter half of the microsomalfraction (density: 1.09–1.11 g cm^–3). Ipomeamarone15-hydroxylase activity was found in heavier half of the microsomalfraction (density: 1.10–1.14 g cm^–3). We proposethat this tissue has two rough-surfaced endoplasmic reticulumspecies, only one of which carries phosphorylcholine-glyceridetransferase, and that the cytochrome P-450 system is localizedon the species lacking the enzyme. Cinnamic acid 4-hydroxylaseactivity was mainly found in a fraction that had densities of1.17–1.19 g cm^–3 and contained vesicular particlesof various sizes. ¹ Present address: Laboratory of Food Hygienics, Faculty ofAgriculture, Kagawa University, Miki-cho, Kida-gun, Kagawa 761-07,Japan. (Received September 6, 1984; Accepted December 27, 1984)