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.     

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.     

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)     

Activation of Protein Synthesis and Biogenesis of Mitochondrial Particles during Aging of Discs of Sweet Potato Root Tissue

Protein synthesis in mitochondrial and supernatant fractions of sweet potato root tissue was found to be activated up to about 3 and 1.5 times in response to wounding, respectively. The activation seemed to take place within 8 hr after slicing. Sucrose density gradient centrifugation of mitochondrial fraction prepared from the aged sliced tissue showed the presence of new fraction of mitochondrial particles which were not seen in the case of fresh tissue. The particles in the fraction were labeled by radioactive leucine in vivo more rapidly than the other particles. Chloramphenicol treatment of tissue before aging blocked the development of these particles. These results suggest that the particles were newly formed during aging.     

Wounding-induced Enhancement of the Activity of Chromatin-bound DNA-Dependent RNA Polymerases in Sweet Potato Root

Chromatin fractions were isolated from intact and wounded sweet potato root tissues. The synthesis of RNA by the chromatin fractions was dependent on four ribonucleoside triphosphates and a divalent cation such as Mg²⁺ and Mn²⁺, Mn²⁺ being most effective. Whereas phosphate did not interfere with the polymerase reaction, it was totally blocked by pyrophosphate. The reaction was inhibited by DNase and actinomycin D as well as RNase and trypsin. The RNA polymerases of sweet potato root needed SH-groups for catalysis. Activity of chromatin-bound RNA polymerases (EC 2.7.7.6) promptly increased in the 6 hr after wounding and then decreased gradually up to 24 hr. Under the present experimental conditions it was mostly due to the activity of RNA polymerase I. RNA polymerase II contributed only about 5 to 15% to the total activity. The increase in the activity after wounding was completely inhibited by cycloheximide. Plant hormones such as 2,4-dichlorophenoxyacetic acid, gibberellic acid and dibutyryl cyclic adenosine 3′,5′-monophosphate stimulated the increase in RNA polymerases three to four times after wounding. Ethylene partially suppressed the wound-induced increase of RNA polymerases.     

Morphological Changes in Chilling Injured Sweet Potato Root

Hydrophobicity and amounts of polar groups on the cell surface were determined by the use of fluorescent probe, colloid titration, and acid titration. Surface hydrophobicity of hydrocarbon-grown cells was about 7 times greater than that of glucose-grown cells of the same strain, while amounts of polar groups did not differ so much. Adsorption of cells to air bubbles was maximum at pH 3. Langmuir’s adsorption isotherm held for the adsorption. Affinity to air bubbles of hydrocarbon-grown cells was 1.8 times greater than that of glucose-grown cells, while the theoretical maximum amounts of cells to adsorb per unit area of bubbles were equal for the both cells.     

Furano-sesquiterpene Reductase from Fungal-inoculated Sweet Potato Root Tissue

Cigarette flavor ingredients adsorbed on activated carbon were recovered by an organic solvent extraction method and a stem desorption method. Recovery by dichloromethane extraction showed the maximum effect and many volatile components, especially the thermal degradation products from sugar analogues, were recovered in a good yield. Their recovered yield and desorption rate depended on the physical properties of the carbons. Most of the volatile components were also recovered by the steam desorption method, but the recovery of components with high boiling points was very low by steam desorption. The difference in recovered yield from the carbons is explained by the specific surface area of the carbons measured before and after the desorption procedure.     

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.     

Increase in Catalase mRNA in Wounded Sweet Potato Tuberous Root Tissue

Catalase protein, as well as its activity, increases in woundedsweet potato tuberous root tissue [Esaka et al. (1983) PlantCell Physiol. 24: 615]. Whether catalase mRNA increases in woundedtissue was examined with a hybridization probe of a cDNA forsweet potato catalase mRNA. The content of catalase mRNA inthe tissue increased after a lag phase of 10 h to reach a maximumat 30 h after wounding, whereas total RNA content increasedwithout a lag phase. The increase in the mRNA content afterthe lag phase preceded that in catalase activity. In the earlystages after wounding, catalase mRNA in polysomes increasedin spite of no increase in the total content of mRNA in thetissue. We propose that an increase in catalase mRNA is responsiblefor the increase in catalase protein in wounded sweet potatotuberous root tissue. In the early stage after wounding, however,the translation of catalase mRNA seems to be activated throughincreased availability of ribosomes. (Received January 28, 1987; Accepted May 6, 1987)     

Purification and Properties of Catalase from Sweet Potato Root Microbodies

Catalase was isolated in a pure form from sweet potato rootmicrobodies by simple procedures including ammonium sulfatefractionation and Sepharose 6B column chromatography. A singleprotein band was detected after polyacrylamide gel electrophoresisof the purified preparation. The catalase consisted of polypeptideswith a molecular weight of 60,000 when analyzed by sodium dodecylsulfate-polyacrylamidegel electrophoresis, while the molecular weight of the enzymewas about 240,000 when estimated from sucrose density gradientcentrifugation. The enzyme's ratio of absorbance at 280 nm tothat at 405 nm was about twice that of mammalian catalase. Thecatalase showed a maximal activity at pH 6.5–8.5 but wasstable only at alkaline pHs. In double immunodiffusion tests,antiserum against the purified preparation formed a single precipitinline with the crude soluble fraction from sweet potato roottissue as well as with the purified preparation. The antiserumhad no ability to inhibit the activity, but catalase in boththe crude fraction and the purified preparation was completelyprecipitated by the antiserum. (Received August 20, 1981; Accepted January 5, 1982)     

Ethylene Production in Sweet Potato Root Tissue Infected by Ceratocystis fimbriata

The rate of ethylene production by sweet potato (Ipomoea batatasLam. cv. Norin No. 1) root tissue infected with Ceratocystisfimbriata Ell. & Halst. increased markedly during incubationat 29?C under high relative humidity. During incubation thefungus progressively invaded root tissue. The rate of ethyleneproduction reached a peak two days after inoculation when thebrowning region that contained the penetrating mycelia had expandedinward about 0.3 mm from the surface, followed by a declinein ethylene production. Apparently, the 1-aminocyclopropane-1-carboxylicacid (ACC) synthase activity was not high enough, and the amountof ACC in the infected tissue was too low to account for thehigh rate of ethylene production throughout the incubation period.Ethylene production by the infected tissue showed scarcely anyinhibition by amino-ethoxyvinylglycine, a specific inhibitorof ACC synthase. These findings suggest that the pathway ofethylene biosynthesis that operates in infected sweet potatoroot tissue may differ from the methionine pathway in whichACC serves as an intermediate. (Received March 24, 1984; Accepted June 27, 1984)     

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.     

The Presence of Two Forms of Succinate Dehydrogenase in Sweet Potato Root Mitochondria

Succinate dehydrogenase was partially purified from sweet potatoroot tissue by solubilization of the enzyme from the submitochondrialparticles, ammonium sulfate fractionation, and DEAE-cellulosecolumn chromatography. Sweet potato succinate dehydrogenaseexisted in two forms; these were separated by disc polyacrylamidegel electrophoresis or by hydroxyapatite column chromatography.There was a difference in the electric charge of the molecule,but not in the molecular weights of the two forms. No differencewas detected between the two forms of succinate dehydrogenasewith respect to their K_m values for succinate, pH-optimums andsubunit compositions. The two subunits that make up the enzymehave molecular weights of about 26,000 and 65,000. ¹ This work was supported in part by Grant-in-Aid 411308 forScientific Research from the Ministry of Education, Scienceand Culture of Japan. (Received November 28, 1981; Accepted February 17, 1982)     

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

Amino acid sequence and peptide-carbohydrate linkage of GP–I–a and GP–I–b, which are two glycopeptides out of three obtained from the saccharogenic amylase of Rhizopus javanicus sp. 3–46, were investigated. By the dinitrophenylation and the subtractive Edman degradation the sequence of GP–I–a and GP–I–b was determined to be respectively.

A glycosylamine type linkage between asparagine and N-acetylglucosamine residue was proved for GP–I–a by the use of the enzyme, β-aspartylglycosylamine amide hydrolase. It seems likely that the peptide-carbohydrate linkage of GP–I–b is also a glycosylamine type linkage.     

Isolation of Functional RNA from Periderm Tissue of Potato Tubers and Sweet Potato Storage Roots

A reliable and efficient protocol is given for the isolation of mRNA from the periderm of potato tubers and sweet potato storage roots. The method relies on a urea-based lysis buffer and lithium chloride to concentrate total RNA away from most of the cytoplasmic components and to prevent oxidation of phenolic complexes. To enhance the physical separation of the RNA from other macromolecular components, the RNA fraction was incubated in the presence of the cationic surfactant Catrimox-14. Poly(A)⁺ mRNA was separated from total RNA and other contaminants by using Promega's MagneSphere technology. The mRNA was suitable for cDNA library construction and RNA fingerprinting.     

甘薯块根生长及其淀粉体发育过程的解剖结构特征

为了探明甘薯块根的生长及其淀粉体的发育规律,该试验以甘薯品种‘徐薯22’为材料,采用树脂半薄切片等方法对甘薯块根的生长及其淀粉体的发育进行观察研究。结果表明:(1)甘薯块根完成初生生长的时间短,块根初生结构由表皮、皮层和中柱构成,块根横截面上皮层所占比例比中柱大。(2)甘薯移栽后10 d块根开始次生生长,次生生长形成维管形成层和木栓形成层;随着块根次生生长,位于次生木质部分散导管周围的薄壁细胞脱分化,通过平周分裂产生副形成层;维管形成层、木栓形成层和副形成层的共同作用使块根快速膨大。(3)淀粉体在块根进入次生生长时首先在皮层细胞产生,随后大量出现在次生生长产生的薄壁细胞中,块根中淀粉体的发生及发育总体上表现出由外向内的顺序。(4)块根薄壁细胞中的淀粉粒有单粒和复粒两种类型;块根生长早期,薄壁细胞中主要以复粒淀粉为主,生长后期主要以单粒淀粉为主;块根生长过程中,包含复粒淀粉的淀粉体可通过分裂形成包含单粒淀粉的淀粉体。(5)淀粉可在块根生长的整个时期积累,其中以块根生长中期积累速度最快。     

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)