Muscular outputs during dynamic bench press under stable versus unstable conditions

Previous studies have suggested that resistance training exercise under unstable conditions decreases the isometric force output, yet little is known about its influence on muscular outputs during dynamic movement. The objective of this study was to investigate the effect of an unstable condition on power, force, and velocity outputs during the bench press. Twenty male collegiate athletes (mean age, 21.3 +/- 1.5 years; mean height, 167.7 +/- 7.7 cm; mean weight, 75.9 +/- 17.5 kg) participated in this study. Each subject attempted 3 sets of single bench presses with 50% of 1 repetition maximum (1RM) under a stable condition with a flat bench and an unstable condition with a Swiss ball. Acceleration data were obtained with an accelerometer attached to the center of a barbell shaft, and peak outputs of power, force, and velocity were computed. Although significant loss of the peak outputs was found under the unstable condition (p < 0.017), their reduction rates remained relatively low, approximately 6% for force and 10% for power and velocity outputs, compared with previous findings. Such small reduction rates of muscular outputs may not compromise the training effect. Prospective studies are necessary to confirm whether the resistance training under an unstable condition permits the improvement of dynamic performance and trunk stability.     

Formation of Pungent Principles in Fruits of Sweet Pepper,Capsicum annuum L. var. grossum during Post-harvest Ripening under Continuous Light

Pungent principles (Capsaicinoid(s)) were found to be produced in fruits of sweet pepper, Capsicum annuum L. var. grossum, during post-harvest ripening under continuous light. The initial formation was observed after 4 days’ ripening. After 7 days’ ripening, the capsaicinoids content in placenta increased to 12.9 μg per fruit, which was 2.5-fold of that in pericarp. No pungent principles were detected in fruits during ripening in the dark and in seeds under continuous light. In placenta, the formation of dihydrocapsaicin and nordihydrocapsaicin which are the vanillylamides of saturated branched fatty acids was higher than that of capsaicin which is the vanillylamide of an unsaturated one. Remarkable formation and accumulation of carotenoid were also observed during post-harvest ripening under continuous light.     

Intracellular Distributions of Enzymes and Intermediates Involved in Biosynthesis of Capsaicin and Its Analogues in Capsicum Fruits

Phenylalanine ammonia-lyase, trans-cinnamate 4-monooxygenase, and capsaicinoid synthetase [Agric. Biol. Chem., 44, 2907 (1980)] activities were investigated in the subcellular fractions from protoplasts of placenta of Capsicum fruits. The subcellular distribution of intermediates of the capsaicinoid biosynthesis, trans-cinnamic acid and trans-p-coumaric acid, and capsaicinoid were also investigated. The activity of trans-cinnamate 4-monooxygenase and capsaicinoid synthetase was in the vacuole fraction. While the activity of phenylalanine ammonia-lyase was in the cytosol fraction. After feeding l-[U-¹⁴C]phenylalanine to the protoplast, the newly synthesized trans-p-coumaric acid and capsaicinoid were found in the vacuole fraction, while trans-cinnamic acid was not in the vacuole fraction. The possible role of the vacuole on the biosynthesis of capsaicinoid is also discussed.     

Intein-based biosynthetic incorporation of unlabeled protein tags into isotopically labeled proteins for NMR studies

Segmental isotopic labeling of proteins using protein ligation is a recently established in vitro method for incorporating isotopes into one domain or region of a protein to reduce the complexity of NMR spectra, thereby facilitating the NMR analysis of larger proteins. Here we demonstrate that segmental isotopic labeling of proteins can be conveniently achieved in Escherichia coli using intein-based protein ligation. Our method is based on a dual expression system that allows sequential expression of two precursor fragments in media enriched with different isotopes. Using this in vivo approach, unlabeled protein tags can be incorporated into isotopically labeled target proteins to improve protein stability and solubility for study by solution NMR spectroscopy.     

Electron-microscopic immunocytochemistry of neuropeptide Y immunoreactive innervation of vasopressin neurons in the paraventricular nucleus of the rat hypothalamus

The neuropeptide Y (NPY) immunoreactive synaptic input to neurons containing neurophysin II (NP II), the carrier protein of vasopressin (VP), was observed in the paraventricular nucleus (PVN) of the rat hypothalamus by double-labeling immunocytochemistry combining the preembedding peroxidase-antiperoxidase (PAP) method with the postembedding immunogold staining method at the electron-microscopic level. NPY-like immunoreactivities were detected by the PAP method in the dense granular vesicles (70-100 nm in diameter) in the immunoreactive presynaptic axon terminals. NP II-like immunoreactive large neurosecretory granules labeled with gold particles were found in the neurons receiving synaptic input of the NPY-like immunoreactive terminals. This suggests that NPY may be a neurotransmitter or neuromodulator and that NPY neurons may, through synaptic contacts, regulate the secretion of VP neurons.     

Fine structure of neurons synthesizing vasoactive intestinal peptide in the human colon from patients with Hirschsprung's disease

Summary The fine structure of neuronal perikarya and processes containing VIP-like immunoreactive material in the colon of patients with Hirschsprung's disease was investigated by immunoelectron microscopy. No VIP-like immunoreactive terminals were found in Auerbach's plexus of the ganglionic segment. However, VIP-like immunoreactive preterminal axons were frequently found to make synaptic contact with both immunoreactive and non-immunoreactive elements within Meissner's plexus. Therefore, the function of the VIP neurons in Auerbach's plexus seems to differ from that in Meissner's plexus. In the oligoganglionic segment, there were a few VIP-like immunoreactive processes, but no VIP-like immunoreactive synaptic formations. VIP-like immunoreactive processes were rarely encountered in the aganglionic segment. In both the oligo-and aganglionic segments, bowel relaxation is considered to be disturbed due to the lack of synaptic contacts of VIP-like immunoreactive neurons with other neuronal components.This work was supported in part by a grant (no. 57370002) from the Ministry of Education, Science and Culture, Japan     

Identification of viruses infected in Rehmannia glutinosa Libosch. var purpurea Makino and effect of virus infection on root yield and iridoid glycoside contents

Virus free plants of Rehmannia glutinosa Libosch. var. purpurea Makino were obtained through meristem tip tissue cultures from plants infected with a mixture of tabocco mosaic virus(TMV), a member of the carlavirus group, and an unknown spherical virus. The re-infection rate of the virus free plants by TMV in the field was determined by enzyme linked immunosorbent assay(ELISA). Twenty seven percent of the plants were re-infected during the first year, 31 % by the end of second year, and 63 % by the end of the third year. The yield of root and iridoid glycoside contents gradually decreased each year. These results led to the conclusion that virus infection causes marked decrease of the yield of roots and productivity of secondary metabolites.     

Roles of PsbI and PsbM in photosystem II dimer formation and stability studied by deletion mutagenesis and X-ray crystallography

PsbM and PsbI are two low molecular weight subunits of photosystem II (PSII), with PsbM being located in the center, and PsbI in the periphery, of the PSII dimer. In order to study the functions of these two subunits from a structural point of view, we crystallized and analyzed the crystal structure of PSII dimers from two mutants lacking either PsbM or PsbI. Our results confirmed the location of these two subunits in the current crystal structure, as well as their absence in the respective mutants. The relative contents of PSII dimers were found to be decreased in both mutants, with a concomitant increase in the amount of PSII monomers, suggesting a destabilization of PSII dimers in both of the mutants. On the other hand, the accumulation level of the overall PSII complexes in the two mutants was similar to that in the wild-type strain. Treatment of purified PSII dimers with lauryldimethylamine N-oxide at an elevated temperature preferentially disintegrated the dimers from the PsbM deletion mutant into monomers and CP43-less monomers, whereas no significant degradation of the dimers was observed from the PsbI deletion mutant. These results indicate that although both PsbM and PsbI are required for the efficient formation and stability of PSII dimers in vivo, they have different roles, namely, PsbM is required directly for the formation of dimers and its absence led to the instability of the dimers accumulated. On the other hand, PsbI is required in the assembly process of PSII dimers in vivo; once the dimers are formed, PsbI was no longer required for its stability.     

Increase in the activity of Rhizopus delemar lipase on water-soluble esters by its binding with phosphatidylcholine

Rhizopus (Rh.) delemar (ATCC 34612) C-lipase was found to exhibit a slight activity towards water-soluble esters. The hydrolytic reaction of this lipase on alpha-naphthyl acetate was competitively inhibited by the presence of olive oil or Tween 80. This finding showed that both substrates, insoluble triglyceride and water-soluble ester, were hydrolyzed at the same site on the enzyme. The activities on water-soluble esters (alpha-naphthyl acetate, beta-naphthyl acetate, methyl acetylsalicylate and Tween 80) increased on binding of lipase with phosphatidylcholine (PC), although the activity on olive oil did not change. The increase in activity on water-soluble esters was due to the increase in the Vmax for its hydrolysis. It appears that local structural change of the catalytic site on lipase occurred on binding of PC to the lipase molecule and resulted in an increase in the activity on water-soluble esters. The temperature dependence of the hydrolysis of water-soluble esters demonstrated that the activation energy was lowered on binding of PC to the lipase molecule, and this resulted in an increase in the activity.     

Identification of suberimidate cross-linking sites of four histone sequences in H1-depleted chromatin. Histone arrangement in nucleosome core

The arrangement of 8 histones in the nucleosome core has been investigated by identifying the sites of 4 histone sequences cross-linked with a bifunctional amino-group reagent, dimethyl suberimidate, selected from among 4 diimidoesters of various linker lengths examined. H1-depleted calf thymus chromatin was allowed to react with 14C-labeled suberimidate at pH 8.5 and 0 degrees C. The cross-linked chromatin was then digested exhaustively with trypsin. Almost all the histone fragments were released from the chromatin with 0.25 M HCl and chromatographed on several columns and on paper. Cross-linked peptides were detected by analyzing the content of radioactive suberimidoylbislysine after acid hydrolysis. The chromatographic procedure developed here showed that the whole histone fragments contained 29 mol% of the total linked reagent as suberimidoylbisylsine. The 5 finally purified cross-linked peptides were identified from the total and N-terminal amino acids of each pair of peptides separated by two-dimensional cellulose thin layer chromatography after cutting the linker by ammonolysis. Thus, intramolecular cross-linking was found between Lys-5 and Lys-9 of H2A, and Lys-34 and Lys-85 of H2B, while intermolecular cross-linking was found between Lys-24 (or 27) of H2B and Lys-74 of H2A, Lys-85 of H2B and Lys-91 of H4, and Lys-120 of H2B and Lys-115 of H3 and/or Lys-77 of H4. Most of these lysine residues are located in the DNA-binding segments of the 4 histone sequences identified previously [Kato, Y. & Iwai, K, (1977) J. Biochem. 81, 621--630]. All the 5 or 6 cross-links can be located in a heterotypic tetramer consisting of one molecule each of H2A, H2B, H3, and H4, and a model of the histone arrangement in the tetramer is proposed. Two such tetramers may compose to the histone octamer in the nucleosome core.