Search

(1) 15種類の新鮮野菜のビタミンC (VCと略）量を，正確に分析定量できるHPLCポストカラム誘導体法で測定した．その結果，総VC量に占めるアスコルビン酸（AsAと略）の割合を平均すると92.8%であった． (2）野菜（15種）の調理直後の総VCの残存率は茹で調理品より，炒め·揚げ調理品の方が高かったが，酸化型VC (DHA）の割合も後者で高かった．24時間冷蔵後のAsA残存率の平均値は茹で調理品の方が高い傾向にあった．したがって，調理野菜からVCを効率よく摂るためには，調理直後に食する場合は炒め調理法が，時間をおいて食する場合は煮（茹で）調理法が好ましいといえる． (3）市販惣菜（8品）の総VC量は調理直後の値の半分以下であり，AsA量は約1/4と著しく少なかった．

Transgenic tobacco plants expressing the ascorbate oxidase (AAO) gene in sense and antisense orientations, and an Arabidopsis mutant in which the T-DNA was inserted into a putative AAO gene, were used to examine the potential roles of AAO for salt-stress tolerance in plants. AAO activities in the transgenic tobacco plants expressing the gene in sense and antisense orientations were, respectively, about 16-fold and 0.2-fold of those in the wild type. Under normal growth conditions, no significant differences in phenotypes were observed, except for a delay in flowering time in the antisense plants. However, at high salinity, the percentage germination, photosynthetic activity, and seed yields were higher in antisense plants, with progressively lower levels in the wild type and the sense plants. The redox state of apoplastic ascorbate in sense plants was very low even under normal growth conditions. Upon salt stress, the redox state of symplastic and apoplastic ascorbate decreased among the three types of plants, but was lowest in the sense plants. The hydrogen peroxide contents in the symplastic and apoplastic spaces were higher in sense plants, progressively lower in the wild type, followed by the antisense plants. The Arabidopsis T-DNA inserted mutant exhibited very low ascorbate oxidase activity, and its phenotype was similar to that of antisense tobacco plants. These results suggest that the suppressed expression of apoplastic AAO under salt-stress conditions leads to a relatively low level of hydrogen peroxide accumulation and a high redox state of symplastic and apoplastic ascorbate which, in turn, permits a higher seed yield.

(1) オレガノ葉のDPPHラジカル捕捉活性および亜硝酸法で測定したO2-捕捉活性は,生葉100g当たり13400μmol AsA当量および7380μmol AsA当量であり,両者とも加熱調理後に活性が1.3倍に増加した.(2) オレガノ葉の主なポリフェノール化合物はロズマリン酸であった.加熱調理後にロズマリン酸を始め,プロトカテキュ酸,コーヒー酸が増大したが,中でも顕著に増大したポリフェノール化合物を分取し,機器分析により3-(3,4-ジヒドロキシフェニル)乳酸と同定した.これは,加熱調理操作中にロズマリン酸が加水分解して生成されたものではなかった.(3) オレガノ葉のDPPHラジカル捕捉活性の約55%が,O2-捕捉活性の約30∼40%が,本研究で同定した4種のポリフェノール化合物,3-(3,4-ジヒドロキシフェニル)乳酸,プロトカテキュ酸,コーヒー酸およびロズマリン酸によって説明できた.

In higher plants, the terminal step of L-ascorbic acid (AsA) biosynthesis is catalyzed by the enzyme L-galactono-1,4-lactone dehydrogenase (EC 1.3.2.3, GalLDH). We generated AsA-deficient transgenic tobacco BY-2 cell lines by antisense expression of the GalLDH cDNA that was amplified from BY-2 cells using PCR. Two transgenic cell-lines, AS1-1 and AS2-2, having a marked expression of antisense RNA were analyzed. Antisense suppression of GalLDH mRNA led to a significant decline in the GalLDH activity. The AsA levels in the transgenic cell lines were found to be 30% lower than the wild-type BY-2 cells. In synchronous cultures, division of AS1-1 and AS2-2 cells was restrained with a concomitant decrease in mitotic index that was probably due to a decline in AsA levels. The rate of cell growth was also found to be less than that of the wild-type cells. Interestingly, there was a significant phenotypic difference between the transgenic and wild-type cells. The calli of AS1-1 and AS2-2 appeared to be sticky and soft. Back extrusion method also showed that AsA-deficient BY-2 callus was rheologically soft. Furthermore, microscopic analysis revealed that AS1-1 and AS2-2 cells were abnormally slender, suggesting a potential for a significant and a uni-axial elongation. Thus, we observed that decline in the AsA levels has an adverse effect on the division, growth and structure of a plant cell.

"Two different methods were used to clarify whether total measured vitamin C (ascorbic acid plus dehydro-ascorbic acid) content of fresh, frozen and cooked vegetables from commercial sources depends on the method used. Total vitamin C content in frozen and cooked vegetables measured by HPLC was only 47.5% of that measured by the colorimetric method. Such an overestimation of vitamin C of prepared vegetables by the colorimetric method was due to the color development from other compounds such as 2, 3-diketogulonic acid, seasonings, sugar and starch. Total vitamin C content in cooked vegetables from commercial sources measured by HPLC should be one third to one fifth of that in fresh vegetables."

魚肉冷蔵中のIMPの分解に関与する2酵素に対する塩の影響をスケトウダラおよびシロギスについて調べた.1. 5'-ヌクレオチダーゼ:スケトウダラから抽出したそれの至適pHは8.0付近で, IMPに対する見かけのKm値は0.83mMであるのに対し,シロギス酵素の至適pHはpH 9.0以上, Km値は0.18mMであった.いずれの活性も塩によって阻害され,その程度はCaCl2>食塩No.1, NaCl, MgCl2>食塩No.2, No.3, KClの順であった. NaClによる阻害は不拮抗的で,Ki値はスケトウダラで0.38M,シロギスで0.36Mであった.2. プリンヌクレオシドホスホリラーゼ:スケトウダラから抽出した酵素のHxRに対する見かけのKm値は0.20mMであった,その活性はNaClによってほとんど阻害されなかったが, KCl, MgCl2によって阻害され,食塩No.2, No.3, CaCl2ではむしろ活性化された.一方,シロギスから抽出した酵素のKm値は0.10mMであり,その活性はNaCl, KCl>食塩No.1, No.2, No.3, CaCl2>MgCl2の順に阻害された.NaClによる阻害は非拮抗的で,そのKi値は1.0Mであった.3. これらの2種類の酵素に及ぼす塩の影響を調べることによって,魚肉の冷蔵中に起こるIMPの減少やHxの生成に対する塩類の抑制機構が酵素レベルで説明できた.

"愛知県安城農協ではいちじく果実の加工品として,前報で述べたワインの他にシャムも製造し,特産品として販売している.西欧では種々の果実をジャムにして食しているが,日本では,いちご,りんご,夏みかんのジャムが主である 近年,食の洋風化に伴いアンズ,ブルーベリーなども加わり,シャムの種類も多くなった.いちじくはペクチン音量が多くジャムに適した果物といえるが,安城で試みられたのが始めてである.そこで日常よく食しているいちごジャムと比較しつつ,いちじくジャムの食味特性と嗜好特性を明らかにするため,老若男女のパネルを用い官能検査を行った その結果,幾つかの知見が得られたので報告する"

"日本では古くからいちしくは薬の木と言われ,昔はどの家の庭先にも1～2本植えられ,非京に身近かな果物であったが,現在では各家庭の庭先から姿がみられなくなった ここ愛知県の三河地方は米の転換作物としていちじくの栽培に積極的に取り組み,日本一の生産地となっている いちじくの果実は生食するのが一般的であるが,果実の保存ができないので,安城市では加工品として新たにいちじくワインやジャムを開発し,特産品として精力的に販売を進めている そこで,いちじくワインの食味特性と嗜好特性を知るため,従来あるぶどうワインと比較しつつ,老若男女をパネルとして官能検査を行った その結果,いちじくワインの特性が明らかになり,改良点,普及対象,飲み方について新たな知見が得られたので報告する"

We found that dehydrated legume seeds (6 genera, 19 species and cultivated varieties) contained considerable amounts of vitamin C (VC). The average value of total VC content per 100 g of dry weight in dehydrated seeds varied from 0.24 mg (kidney beans) to 4.14 mg (green peas). Yard beans showed highest values among all legumes examined here in the both dehydrated and rehydrated forms (3.19 and 10.8 mg, respectively). By soaking for 16 h in the dark at 20(o)C, total VC contents of black grams and mung beans increased to 3.1- and 4.5-fold, respectively. However, three varieties of green peas (Hakuryu, Kurumeyutaka, and Nankaimidori) significantly lost their VC during the same soaking treatment. Total VC content of a rehydrated and cooked mung beans was higher than that of a dehydrated form. Appreciable amounts of total VC were detected in the immature seeds of six different genera such as yard beans, kidney beans, broad beans, green peas, soybeans and peanuts. Except for mung beans, 70-100% of VC in dehydrated seeds of adzuki beans, broad beans, green peas, black soybeans, and soybeans was lost by boiling. Total VC and L-ascorbic acid in mung beans, green peas, broad beans, black soybeans, and adzuki beans remained even after boiling, suggesting that it is possible to obtain VC from the cooked forms of these legume seeds.

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC1.1.1.34), the key enzyme in isoprenoid biosynthesis, was purified from microsomes of potato tuber tissue, and a polyclonal antibody and two monoclonal antibodies against the purified enzyme were prepared. HMGR protein content was measured by immunotitration and radioimmunoassay using these antibodies. HMGR activity was very low in the fresh tissues of both potato tuber and sweet potato root. The activity in potato tuber was increased by cutting and further by additional fungal infection of the cut tissues. In sweet potato root tissue, the activity was scarcely increased after cutting alone, but was markedly increased by additional fungal infection or chemical treatment. The HMGR protein contents in both fresh potato tuber and sweet potato root tissues were also very low, and increased markedly in response to cutting and fungal infection. From these results, we proposed a hypothesis on the induction mechanism of HMGR after cutting and fungal infection in potato tuber and sweet potato root tissues.

L-Galactono-gamma-lactone dehydrogenase (EC 1.3.2.3, GLDHase) was partially purified from mitochondria of sweet potato tuberous roots over 600-fold on a specific activity basis, followed by purification of the enzyme protein of 56 kDa by a preparative SDS-PAGE. The absorption spectrum of the hydroxylapatite column-purified GLDH-ase showed peaks at 448 and 373 nm, suggesting the presence of flavin as a prosthetic group. The activity of GLDH-ase was inhibited by lycorine, an alkaloid which inhibits ascorbic acid biosynthesis in vivo. N-terminal partial sequences of four internal polypeptides generated by partial digestion of GLDHase with V8 protease were determined. The deduced nucleotide sequences were used to amplify a cDNA fragment of the GLDHase gene. The clone encoded a polypeptide of 581 amino acid residues with a molecular mass of 66 kDa. The deduced amino acid sequence showed 77% identity with that of cauliflower GLDHase, and significant homology to those of L-gulono-gamma-lactone oxidase (22% identity) from rat and L-galactono-gamma-lactone oxidase from yeast (17% identity), which are enzymes involved in L-ascorbic acid biosynthesis in these organisms. The absorption spectrum and cDNA sequence suggested that the flavin group bound noncovalently. We conclude that GLDHase, L-gulono-gamma-lactone oxidase and L-galactono-gamma-lactone oxidase are homologous in spite of the difference in substrates and electron acceptors. Genomic Southern analysis suggested that GLDHase gene exists as a single copy in the genome of sweet potato.

The distribution of the glucosides of trans - and cis -2-hydroxy cinnamic acid and of the β-glucosidase which hydrolyzes the latter glucoside was examined in preparations of epidermal and mesophyll tissue obtained from leaves of sweet clover ( Melilotus alba Desr.). The concentrations of glucosides in the two tissues were about equal when compared on the basis of fresh or dry weight. Inasmuch as the epidermal layers account for no more than 10% of the leaf volume, the mesophyll tissue contains 90% or more of the glucosides. Vacuoles isolated from mesophyll protoplasts contained all of the glucosides present initially in the protoplasts. The specific activities of the β-glucosidase in the two tissues were also similar; thus, most of the enzyme is contained in mesophyll tissue. However, the amount of enzyme in mesophyll protoplast extracts amounts to only 1 to 2% of the activity present in leaf homogenates when chlorophyll was the basis for comparison. (This small amount of coumarin-β-glucosidase present in protoplasts is not associated with chlorophyll-containing fractions.) In contrast, 90% of the uridine diphosphate glucose- o -coumaric acid glucosyl transferase activity present in leaf homogenate was recoverable in protoplasts prepared from intact leaves. Such results indicate that most of the coumarin-β-glucosidase in M. alba leaves is located in the extracytoplasmic space. Only a small fraction (7%) of this extra cytoplasmic β-glucosidase was associated with individual cells or cell clusters isolated from clover leaves.

Ipomeamarone 15-hydroxylase activity was found in a microsomal fraction from cut-injured and Ceratocystis fimbriata -infected sweet potato ( Ipomoea batatas Lam. cv. Norin No. 1) root tissues and its optimum pH was 8.0. The enzyme reaction required O 2 and NADPH. The K m values calculated for ipomeamarone and NADH were approximately 60 and 2 micromolar, respectively. NADPH alone had little effect on enzyme activity but activated the reaction in the presence of low concentrations of NADPH. Ipomeamarone 15-hydroxylase activity was strongly inhibited by p -chloromercuribenzoic acid and markedly suppressed by cytochrome c and p -benzoquinone. KCN was an activator rather than an inhibitor for the reaction. CO inhibited the activity strongly and its inhibition was partially reversed by light. CO difference spectra of the reduced microsomal fraction showed two absorption maxima at 423 and 453 nm; the latter maximum may be due to a cytochrome P-450. These results suggest that ipomeamarone 15-hydroxylase is a cytochrome P-450-dependent, mixed-function oxygenase. Ipomeamarone 15-hydroxylase activity was not found in fresh tissue of sweet potato roots. However, the activity appeared and increased markedly in response to cut-injury or infection by Ceratocystis fimbriata , and reached a maximum after 24 to 36 hours of incubation. The increase in activity in the latter case was 3- to 5-fold higher than in the former. The time course patterns of development and successive decline in ipomeamarone hydroxylase activities were similar to those for cinnamic acid 4-hydroxylase activity, which had been described as a cytochrome P-450-dependent, mixed-function oxygenase. However, little substrate competition was found between ipomeamarone 15-hydroxylase and cinnamic acid 4-hydroxylase in our preparations.

"新鮮な小魚肉の特性を長期間保持できる貯蔵方法を見いだす目的で,魚肉を異なる方法で貯蔵し,貯蔵中の魚肉の含有タンパク質や遊離アミノ酸の変化および加熱調理後のたたきだんごの物理特性と食味特性を調べた.新鮮キス肉のタンパク質と遊離アミノ酸含量は各々17.1%と1.02%であったが,一週間貯蔵する間に両値とも徐々に減少した.加熱調理後のたたきだんごの破断力や硬さの変化は,全魚を氷水貯蔵した場合に最も大であり,すり身にして冷凍・冷却貯蔵した場合には小であった.食塩を加熱前に加えてだんごをつくると,たたきだんごの物理特性および食味特性が向上した.新鮮なキス肉でつくったたたきだんごの特性を長く保持させる最もよい魚肉貯蔵方法は,食塩添加すり身をつくり冷凍貯蔵する方法であった.", "In order to obtain a knowledge on storage condition of fish or minced fish (surimi) for keeping the properties of the boiled minced meat ball (Tatakidango) of fresh fish, we determined the contents of proteins and free amino acids as well as the physical properties of Tatakidango of stored fish or surimi in different conditions. Contents of proteins and free amino acids of fresh meat of Sillago japonica were 17.1% and 1.02%, respectively, and both decreased gradually during one-week storage. Changes in the physical properties such as the breakness and hardness of Tatakidango were the most drastic in the case of fish as a whole stored in ice water, and were much less in the case of surimi stored in a refrigerator (+ 5℃) or in a freezer (-25℃). When NaCl was added to the surimi before boiling, the physical properties and sensory evaluation of Tatakidango were improved. In this study, it was found that the best storage condition for keeping the properties of Tatakidango of Sillago japonica was a frozen storage of surimi at -25℃ after adding NaCl."

Ipomeamarone, a furanosesquiterpenoid produced in Ceratocystis fimbriata-infected sweet potato root tissue, was decomposed by neither sweet potato strain nor oak Strain of C. fimbriata. Ipomeamarone inhibited various physiological events of C. fimbriata such as endoconidial germination, germ-tube growth, mycelial growth, endoconidial formation, black coloration of mycelia and normal morphological development of mycelia. The inhibitory effects were not so severe in sweet potato strain, pathogenic to sweet potato, compared with oak strain, non-pathogenic one.

Acetate: CoA ligase (AMP) (EC 6. 2.1. 1, acetyl CoA synthetase, ACS) was found in sweet potato root tissue. When the tissue was infected by Ceratocystis fimbriata, activity of the enzyme was increased several-fold compared to that in fresh tissue and decreased rapidly after reaching a maximum. When cut tissue was incubated without inoculation, the activity was rather decreased.The fact that terpenes such as ipomeamarone are synthesized in diseased tissue but not in cut tissue, strongly suggests that increased activity of ACS in diseased tissue mainly participates in terpene biosynthesis supplying acetyl CoA.

Furano-terpene production in sweet potato root tissue treated with chemicals, such as HgCl2, l-alanine and cAMP was inhibited by antibiotics, such as cycloheximide, blasticidin S, puromycin and chloramphenicol when the antibiotics were administered to the tissue immediately after cutting. However furano-terpene production was not inhibited by antibiotics when they were administered to the 18-hr incubated cut tissue together with chemical elicitors of furano-terpene production. Furano-terpenes were accumulated in the tissue in 5 hr after HgCl2 treatment to the 18-hr incubated cut tissue and the content reached a maximum in 10hr and then decreased gradually. The rate of protein synthesis in the tissue was enhanced in 6 hr after cutting and decreased by 15 hr, then reached a constant rate. HgCl2 treatment to the 24-hr incubated cut tissue did not affect the rate of protein synthesis but cycloheximide administered to the tissue with HgCl2 strongly suppressed the rate of protein synthesis. These data suggest t...

Study of the soluble proteins of sweet potato (Ipomoea batatas L. cv. Norin 1) roots showed that the major protein had an apparent molecular weight of 25,000, and accounted for 60 ~ 70% of the total soluble protein extracted from fresh tissue. The 25-kDa protein exists in two forms, which can be resolved into two bands by nondenaturing polyacrylamide gel electrophoresis. Immunodiffusion and crossed immunoelectrophoresis showed that these forms are immunologically identical. This protein was identified as the antigenic component A of sweet potato root.1) It was degraded to proteins of lower molecular weight (9,500 to 20,000) if the tissue was cut or infected by Ceratocystis fimbriata. As almost none of this 25-kDa protein was detected in roots stored for one year at 10 ~ 12°C, it is probably the storage protein of these roots. Another major protein was identified as β-amylase by immunodiffusion and immunoelectrophoresis. The amount of β-amylase did not change appreciably after cutting or infection, but it ...

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 adeno...

"麺の官能検査をした場合,おいしさに影響する要因が何かを解明する目的で,市販の手延べ・手打ち・機械麺,合計40点の試料について官能検査を実施した.その結果, 1.ゆで麺の水分合量の平均値は74.1±2.6%で,ゆで後の増重率は元の重量の約3倍であった.両者間には相関係数r=0.64で,有意に正の相関関係があった. 2.ゆで麺の断面積と官能評価(総合評価)の間には相関係数r=0.54で,正の相関が認められ,麺線の大さか官能評価に大きく影響することがわかった. 3.手延べ麺と機械麺の官能評価の結果は手延べ麺が「わずかに良い」から「すこし良い」に対し,機械麺は「普通」であった.手延べ麺の方が総合評価,はだあれ,なめらかさ,弾力において危険率1%にて有意に良いと評価され,かたさの点で危険率5%で良いと評価された. 4.機械麺の中の上位評価品と下位評価品の比較をした結果,食味と弾力で危険率1%にて有意差が認められ,かたさの点で危険率5%で有意な差が認められた. 5.麺の総合的な官能評価には弾力と食味が大きく寄与し,各々の寄与率は70%および67%であった."

In addition to HMG-CoA reductase, another HMG-CoA utilizing enzyme is present in the Mt fraction of sweet potato root tissue and its activity interferes with the assay to HMG-CoA reductase activity.

When sweet potato (Ipomoea batatas) root tissue was infected by Ceratocystis fimbriata, activity of the enzyme system from mevalonate to isopentenyl pyrophosphate, especially of pyrophosphomevalonate decarboxylase (EC 4.1.1.33), was increased in the noninfected tissue adjacent to the infected region, preceding the furano-terpene production in the infected region. Cutting and incubation of sweet potato slices did not produce furano-terpenes, and only slightly increased the activity of the enzyme system from mevalonate to isopentenyl pyrophosphate. The enzymic activity in diseased tissue was localized in the soluble fraction, and was higher in the tissue from the surface to a depth of about 5 mm with gradual decrease toward the inner part.Mercuric chloride (0.1%, w/v) and sodium dodecyl sulfate (1.0%, w/v) were utilized as model inducers of furano-terpenes and pyrophosphomevalonate decarboxylase. The mercuric chloride- or sodium dodecyl sulfate-induced response was inhibited by administration of cycloheximide to the discs together with the inducer immediately after disc preparation. When cycloheximide or blasticidin S was applied together with the inducer, to the discs 9 hours or more after disc preparation, the induction was not inhibited but rather stimulated.