Hisateru Mitsuda

Inhibitory effect of ammonium ion on recovery of cryopreserved rice cells

Abstract We examined the effect of post-thaw culture medium on the viability of freeze-thawed rice ( Oryza sativa L. cv. Nihonbare) cells. Elimination of ammonium ion from Linsmaier-Skoogs medium increased the viability in post-thaw culture. However, ammonium ion was needed for the vigorous growth of the cells that had recovered from freezing-injury and unfrozen control cells. These results suggested that ammonium ion was deleterious only to freeze-damaged rice cells; in other words, it inhibited the recovery of the cells from freezing-injury. The composition of post-thaw culture medium is thus important for successful cryopreservation of cultured rice cells.

Changes of blood gas in carp, Cyprinus carpio, anesthetized with carbon dioxide

Abstract 1. 1. Carp were cannulated in the dorsal aorta and the changes in arterial blood gas were examined during 30 min CO2 anesthesia under differing conditions and during the subsequent 60 min recovery period. The mean PaCO2, PaO2, and pHa of the carp (n = 50) before anesthesia were 3, 63, and 7.78 mmHg, respectively. 2. 2. All of the carp became anesthetized to Stage II (initial stage of anesthesia) or higher when treated with water containing high concentrations of CO2 (more than pCO2 = 125 mmHg), while only one carp out often reached Stage II at PwCO2 = 100 mmHg. The mean induction time of anesthesia (Stage II) was 23 (n = 1), 20, 12, and 8 min at PwCO2 = 100,125,175, and 250 mmHg, respectively. At Stage II, the mean PaCO2, PaO2, and pHa were 88–146 mmHg, 181–262mmHg, and 6.61–6.66, respectively. 3. 3. At recovery, the mean PaCO2, PaO2, and pHa were 15–31, 63–175 and 6.95–7.20 mmHg, respectively, the mean recovery time being 8–22 min.

Product specificity of rice germ lipoxygenase

Incubation of linoleic acid with partially purified lipoxygenase from rice germ yielded a ratio of 9-to 13-hydroperoxides of linoleic acid of 97∶3 as measured by high performance liquid chromatography. Under similar conditions, hematin gave the 9- to 13-hydroperoxides at a ratio of 51∶49, and soybean lipoxygenase-a at 9∶91. Infrared spectral analysis revealedcis-trans configuration to predominate in the reaction products with the rice germ enzyme as was with the soybean enzyme.

Effects of a high concentration of CO2 on electrocardiograms in the carp, Cyprinus carpio

1. The effects of a high concentration of CO2 (PCO2 = 250 mmHg and PO2 = 360 mmHg in water) and MS222 (tricaine methanesulfonate, 1/8000 or 1/5000) on the electrocardiogram (ECG) in carp were examined using five kinds of bipolar leads from the body surface. 2. In the carp anesthetized with the high concentration of CO2 for 30 min, the QRS duration, PQ interval and and direction of the QRS axis on the frontal plane significantly changed. Even after recovery from anesthesia, delay in the QRS duration was still recognized. 3. The concentration of CO2 used in this study had an anesthetic action to the same degree as 1/8000 of MS222 and had a much more severe effect on the ECG of the carp than 1/5000 of MS222.

Selenium Content of Foods and Its Average Daily Intake in Japan

種々の食品のセレン含量を, 比色法また螢光法で測定した。魚, その他の海産物, およびニンニク中に著量のセレンが検出された。しかし, 問題となるほど過剰にセレンを含んだものはなかった。さらに, 将来の食糧源としての微生物菌体, 藻類中のセレン含量を測定したが, 全般に低い値であった。今回の分析結果, ならびに分析値および食糧需給調査資料をもとにして, 日本人が1人あたり1日に摂取するセレン量を求めたところ207.7μgであった。この摂取量はカナダ人, アメリカ人とほぼ等しく, 各国とも同等のセレン栄養の状態にあると推察された。

Electrocardiograms recorded from the body surface of the carp, Cyprinus carpio

Abstract 1. 1. The electrocardiograms (ECGs) in five kinds of bipolar leads were recorded from the body surface of the carp under water. 2. 2. Each component constituting the ECG wave could be detected by the present method. 3. 3. The potentials of the ECGs recorded by the present method were relatively small, the values being 2–64 μV. 4. 4. The electrical axis in most carp was directed toward the right lateral side.

A New Sulfur-containing Peptide from Lentinus edodes Acting as a Precursor for Lenthionine

A sulfur-containing peptide, acting as an enzymatic precursor of the aroma-bearing substance, was isolated in crystalline form from fruiting bodies of the shiitake mushroom. The isolation procedure consists of methanol extraction, repeated ion-exchange chromatographies, and crystallization from methanol-water. The common name “lentinic acid” is given for the isolated peptide. Amino acid analysis, performed after acid hydrolysis of the oxidized or desulfurized peptide, indicates involvement of a glutamic acid and S-substituted cysteine sulfoxide in the molecule. Results of enzymatic assays led to the designation of l-configuration for the component amino acids. The presence of a γ-glutamyl peptide bond is shown, since glutamic acid constitutes the N-terminal amino acid and a free amino group is adjacent to a free carboxyl group. The structure proposed for lentinic acid is, The precise structure for the portion in brackets is unidentified.

Enzymic formation of thiamine pyrophosphate in plants.

Evidence was presented by paper chromatographic analysis on the occurrence of an enzyme capable of catalyzing a pyrophosphate transfer from ATP to thiamine in green leaves of various plants. The exclusive localization of the enzyme activity in the 105,000 X g supernatant (in a soluble form) was demonstrated by differential centrifugation of a cell homogentae in 0.25 M sucrose. The enzyme was purified by column chromatography with DEAE-cellulose and by gel filtration with Sephadex G-150. The partially pruified preparation, while contaminated with detectable activity of acid phosphatase, lost the ability of utilizing thiamine monophosphate as the substrate in place of thiamine. These findings lead to the conclusion that thiamine pyrophosphate is formed in green leaves of plants through a direct pyrophosphorylation of thiamine in the presence of ATP and Mg.

Enzymatic pyrophosphorylation of 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine by cell-free extracts of Escherichia coli B

Abstract Cell-free extracts of Escherichia coli B catalyze the direct pyrophosphorylation of 14C-labelled 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine. Radioisotopic and chromatographic evidence show that the product enzymatically formed in this reaction is the pyrophosphate ester of the pteridine. ATP and Mg++ are essential as cofactors for the reaction. The pyrophosphorylation is strongly inhibited by 2-amino-4-hydroxy-6-carboxy-7,8-dihydropteridine.

Effect of Chlorophenol Analogues on the Oxidative Phosphorylation in Rat Liver Mitochondria

The inhibition of chlorophenol analogues on oxidative phosphorylation in rat liver mitochondria was studied using polarographic technique and some new findings that not only pentachlorophenol (PCP) but also other analogues inhibited the oxidative phoshorylation in a similar manner were made. The inhibitory activity was found to be roughly correlated with its dissociation constant of the inhibitor, PCP being the strongest, varying with the number and position of chlorine atoms in the molecule. The mode of the inhibition was classified into three types and discussed in detail.