Structures and Syntheses of Two Phenolic Amides from Piper nigrum L.

Two phenolic amides were isolated from the fruits of white pepper (Piper nigrum L.) and identified to be N-trans-feruloyl tyramine (2a) and N-5-(4-hydroxyphenyl)-2E, 4E-pentadienoyl piperidine (6a) on the basis of chemical and specrtal evidence. Both compounds were synthesized.     

QTL mapping for tuberous stem formation of kohlrabi (<Emphasis Type="Italic">Brassica oleracea</Emphasis> var. <Emphasis Type="Italic">gongylodes</Emphasis> L.)

The tuberous stem of kohlrabi is an important quantitative trait, which affects its yield and quality. Genetic control of this trait has not yet been unveiled. To identify the QTLs controlling stem swelling of kohlrabi, a BC₁ population of 92 plants was developed from a cross of broccoli DH line GCP04 and kohlrabi var. Seine. A wide range of variation in tuberous stem diameter was observed among the mapping populations. We constructed a genetic map of nine linkage groups (LGs) with different types of markers, spanning a total length of 913.5 cM with an average marker distance of 7.55 cM. Four significant QTLs for radial enlargement of kohlrabi stem, namely, REnBo1, REnBo2, REnBo3, and REnBo4 were detected on C02, C03, C05, and C09, respectively, and accounted for the phenotypic variation of 59% for the stem diameter and 55% for the qualitative grading of tuberous stem in classes. Then, we confirmed the stability of identified QTLs using BC₁S₁ populations derived from the BC₁ plants having heterozygous alleles at the target QTL and homozygous kohlrabi alleles at the remaining QTLs. REnBo1and REnBo2 using 128 plants of BC₁68S₁ and 94 plants of BC₁43S₁, respectively, and REnBo3 and REnBo4 using 152 plants of BC₁57S₁ were detected at the same positions as the respective QTLs of the BC₁ population. Confirmation of QTLs in two successive generations indicates that the QTLs are persistent. The QTLs obtained in this study could be useful in marker-assisted selection of kohlrabi breeding, and to understand the genetic mechanisms of stem swelling and storage organ development in kohlrabi and other Brassica species.     

Inhibition of the catalase reaction of Photosystem II by anions

A new binding site for anions which inhibit the water oxidizing complex (WOC) of Photosystem II in spinach has been identified. Anions which bind to this site inhibit the flash-induced S₂/S₀ catalase reaction (2H₂O₂2H₂O+O₂) of the WOC by displacing hydrogen peroxide. Using a mass spectrometer and gas permeable membrane to detect the ³²O₂ product, the yield and lifetime of the active state of the flash-induced catalase (to be referred to simply as flash-catalase) reaction were measured after forming the S₂ or S₀-states by a short flash. The increase in flash-catalase activity with H₂O₂ concentration exhibits a K_m=10–20 mM, and originates from an increase in the lifetime by 20-fold of the active state. The increased lifetime in the presence of peroxide is ascribed to formation of the long-lived S₀-state at the expense of the unstable S₂-state. The anion inhibition site differs from the chloride site involved in stimulating the photolytic water oxidation reaction (2H₂OO₂+4e^-+4H⁺). Whereas water oxidation requires Cl^- and is inhibited with increasing effectiveness by F^-CN^-N₃ ^-, the flash-catalase reaction is weakly inhibited by Cl^-, and with increasing effectiveness by F^-CN^-, N₃ ^-. Unlike water oxidation, chloride is unable to suppress or reverse inhibition of the flash-catalase reaction caused by these anions. The inhibitor effectiveness correlates with the pK_a of the conjugate acid, suggesting that the protonated species may be the active inhibitor. The reduced activity arises from a shortening of the lifetime of the flash-induced catalase active state by 3–10 fold owing to stronger anion binding in the flash-induced states, S₂ and S₀, than in the dark S-states, S₁ and S_-1. To account for the paradoxical result that higher anion concentrations are required to inhibit at lower H₂O₂ concentrations, where S₂ forms initially after the flash, than at higher H₂O₂ concentrations, where S₀ forms initially after the flash, stronger anion binding to the S₀-state than to the S₂-state is proposed. A kinetic model is given which accounts for these equilibria with anions and H₂O₂. The rate constant for the formation/release of O₂ by reduction of S₂ in the WOC is <0.4 s^-1.Abbreviations ADRY acceleration of the deactivation reactions of the water splitting enzyme system Y - BTP bis [tris(hydroxymethyl)methylamino]-propane - CCCP carbonylcyanide m-chlorophenylhyrazone - DCBQ 2,5-dichlorobenzoquinone - DMBQ 2,3-dimethylbenzoquinone - WOC water oxidizing complex     

Molecular Sizes of the Catalytic Units of Oxygen Evolution and the Reaction Center in Photosystem II of Spinach Thylakoids

Target analysis of the PS II reaction in spinach thylakoidsshowed that the respective molecular masses of the catalyticunits for oxygen evolution and the reaction center are about120 kDa and 250 kDa based on a kinetic separation of the tworeaction rates. The size of the oxygen-evolving enzyme agreedwith that determined for the PS II preparation from a thermophiliccyanobacterium by the same means [Nugent and Atkinson (1984)FEBS Lett. 170: 89]. Single hit-inactivation of oxygen evolutionand the PS II reaction center units indicates that each functionis driven by a structurally assembled unit. (Received August 6, 1984; Accepted December 17, 1984)     

Scavenging of Hydrogen Peroxide in Prokaryotic and Eukaryotic Algae: Acquisition of Ascorbate Peroxidase during the Evolution of Cyanobacteria

Ascorbate (AsA) peroxidase was found in six species of cyanobacteriaamong ten species tested. Upon the addition of H₂¹⁸O₂ to thecells of AsA peroxidase-containing cyanobacteria, ¹⁶O₂ derivedfrom water and ¹⁸O₂ derived from H₂^I8O₂ were evolved in thelight. The evolution of ¹⁶O₂ was inhibited by DCMU and did notoccur in the dark, but ^I8O₂ was evolved even in the dark orin the presence of DCMU. Similar light-dependent evolution of¹⁶O₂ was observed in the cells of AsA peroxidase-containingEuglena and Chlamydomonas. However, the cells of AsA perox-idase-lackingcyanobacteria evolved only ¹⁸O₂ in either the light or dark.Furthermore, the quenching of chlorophyll fluorescence inducedby hydrogen peroxide was observed only in the cells of the AsAperoxidase-containing Synechocystis 6803, and not in the cellsof Anacystis nidulans which lacks AsA peroxidase. Thus, cyanobacteriacan be divided into two groups, those that has and those thatlacks AsA peroxidase. The first group scavenges hydrogen peroxidewith the peroxidase using a photoreductant as the electron donor,and the second group only scavenges hydrogen peroxide with catalase. (Received July 23, 1990; Accepted October 18, 1990)     

Matrix-Embedded Osteocytes Regulate Mobilization of Hematopoietic Stem/Progenitor Cells

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Gender differences in effects of 20 days horizontal bed rest on muscle strength in young subjects

Gender differences in the effect of 20 days bed rest (BR) on muscle strength were evaluated in voluntary 11 male and 7 female students. Maximum Isometric Voluntary Contractions (MVC) of 4 right arm muscles (RAM), 5 right leg muscles (RLM), and 2 body trunk muscles were measured with an isometric dynamometer, respectively. Muscle masses (MM) of right arm and leg and body trunk were determined by dual energy X-ray absorptiometry, respectively. The maximum cross sectional area (CSAmax) of right m. quadriceps femoris was measured by magnetic resonance imaging. Elbow flexion MVC in males and all MVC of RLM except knee flexion in both males and females were decreased (p<0.05), but elbow extension MVC in females was increased (p<0.05), while all of other MVC only tended to decrease. However, the decrements in leg MVC were not correlated to the leg MM, and also the decrement in knee extension was not correlated to the CSAmax of m. quadriceps. The reduction of MVC of antigravity muscles might be caused not only by a decrease in MM but also by other factors. The greater decrements of leg MVC during BR were the higher initial level in males, but the inverse was observed in females. However, this discrepancy between males and females cannot be explained in the present study.