Efficiency of electron transport processes

Efficiency of electron transport along the linear chain of molecules was investigated from a dynamic viewpoint. It was proposed that two kinds of efficiency are important for electron transport; one is energy efficiency, the other quantum efficiency. In this paper, these two efficiencies are defined for a linear chain system and the correlation between these quantities and the arrangement of various electron transfers is investigated. The optimization of energy and quantum efficiency is found to set different conditions on the arrangement of the rate constants of electron transfer, and there is strong correlation between neighboring electron transfers. In order to maximize both efficiencies, the rate constants of forward and backward transfers of electrons should be bounded by one another in a limited range. In particular, when there are some bypass reactions on the linear chain, as is the case for photosynthesis and respiration, the rate of the backward transfer should be the same order of magnitude as that of the next forward transfer. The present results are applied to some biological processes. In the early stage of photosynthetic electron transfer it seems that quantum efficiency is more important than energy efficiency. The quantum efficiency is close to unity, whereas a considerable part of the free energy is wasted as heat during the primary electron transfers. On the other hand, in the slower electron transfer processes in photosynthesis and respiration, which take place mostly near equilibrium, the energy efficiency seems to be more important than the quantum efficiency. The relation of these properties to biological function is discussed.     

A critical role for antigen-specific Th1 cells in acute liver injury in mice.

A novel liver injury model was established in mice by targeting of OVA-containing liposomes into the liver, followed by adoptive transfer of OVA-specific Th1 cells. Combined treatment of mice with OVA-containing liposomes and Th1 cell transfer caused an increase in serum transaminase activity that was paralleled with an elevation of serum IFN-gamma levels. In sharp contrast, OVA-specific Th2 cell transfer resulted in an increase of serum IL-4 levels, but did not induce liver injury. Neither NK, NK T, nor CD8+ T cells were required for the Th1-induced liver injury. The liver injury was blocked by anti-IFN-gamma mAb and anti-TNF-alpha mAb, but not by anti-Fas ligand mAb. The Fas/Fas ligand independency was also demonstrated using Fas-deficient lpr mice. These findings indicate that Th1 cells are the major effector cells in acute liver injury.     

Proliferation of Intrahyphal Hyphae Caused by Disruption of csmA, Which Encodes a Class V Chitin Synthase with a Myosin Motor-Like Domain in Aspergillus nidulans

We have found that the Aspergillus nidulans csmA gene encodes a novel protein which consists of an N-terminal myosin motor-like domain and a C-terminal chitin synthase domain (M. Fujiwara, H. Horiuchi, A. Ohta, and M. Takagi, Biochem. Biophys. Res. Commun. 236:75-78, 1997). To clarify the roles of csmA in fungal morphogenesis, we constructed csmA null mutants. The growth rate of the mutant colonies was almost the same as that of the wild-type strain, but hyphal growth was severely inhibited when a chitin-binding reagent, Calcofluor white or Congo red, was added to the medium. Moreover, morphological abnormalities in tip growth and septum formation were identified microscopically. Proliferation of intracellular new hyphae, called intrahyphal hyphae, which behaved as intrinsic hyphae, was the most striking phenotypic feature among them. These phenotypes were not suppressed when the only chitin synthase domain of csmA was expressed under the control of the alcA promoter, whereas they were suppressed when the intact form of csmA was expressed. Therefore, it was concluded that the product of csmA (CsmA) has important roles in polarized cell wall synthesis and maintenance of cell wall integrity and that the myosin motor-like domain is indispensable for these functions.     

Changes in fructose-induced production of glucose in the rat liver following partial hepatectomy.

The fructose-induced production of glucose in the liver after partial hepatectomy (PH) was evaluated by using the liver-perfusion system. There was no significant difference in plasma glucose level between hepatectomized (HX) and sham-operated (SO) rats at 24 h after surgery, and, thereafter, almost similar levels were obtained in both groups. However, the level of serum free fatty acids (FFA) was significantly higher in HX rats than that in SO rats at 24 and 48 h after surgery. When both groups of rats were given fructose by gavage, the increment of plasma glucose was significantly larger in HX rats than in SO rats. Lactate infusion failed to increase the rate of glucose production in perfused livers of both HX and SO rats and there was no significant difference in the activity of hepatic phosphoenolpyruvate carboxykinase. By contrast, fructose infusion elicited a large increase in glucose production in the perfused livers of HX rats at 24 and 48 h after PH. The increase was closely associated with not the change in fructose 2,6-bisphosphate levels but the increment of the intracellular levels of citrate. Treatment of octanoate or oleate, which supplies acetyl-CoA via fatty acid oxidation, mimicked the fructose-induced increase in glucose production in SO rats with a concomitant increase in hepatic levels of citrate. These results suggest that the oxidation of FFA may play an important role in glucose production induced by fructose administration during the early phase of liver regeneration.     

Pulsed column reactor as a novel tool for continuous enzymatic synthesis of peptide in an aqueous/organic biphasic medium

We propose a novel effective method for a continuous peptide synthesis in an aqueous/organic biphasic medium using a pulsed column reactor. N-Formyl-l-aspartyl-l-phenylalanine methyl ester was enzymatically synthesized continuously. With this extractive method using a pulsed column reactor, we can synthesize peptides with a stable performance even if a peptide (or a peptide-amino acid complex) is precipitated due to its high hydrophobicity.     

Cell wall-affecting antibiotics induce expression of a novel gene, drp35, in Staphylococcus aureus.

A novel gene, drp35, of Staphylococcus aureus, which was inducible especially with cell wall-affecting antibiotics, has been cloned. Analysis of differential hybridization with mRNAs enhanced in the presence of beta-lactams resulted in two positive clones that harbored a new gene encoding a 35,845-Da protein (Drp35) and the penicillin-binding protein 2 (PBP2). Immunoblot analysis revealed that the Drp35 protein band was evidently enhanced after 30 min in the presence of beta-lactams. The Drp35 expression was also enhanced with not only beta-lactams, but also vancomycin, bacitracin, and fosfomycin. Homology search revealed that Drp35 was a new protein. Our results revealed that it was specific in S. aureus and respondent to these agents in both methicillin-resistant and -sensitive strains of S. aureus.     

Recycled addition of CD4+ T cell-rich population for induction of human autologous cytotoxic T lymphocytes: A practically efficient method

When CD4⁺ T cell-rich population appears in theinitial trial in induction cultures of humanautologous cytotoxic T lymphocytes (CTL), the cultureresults frequently in no or weak killing activity andtherefore usually be discarded as an `unsuccessful'CTL induction culture. However, addition of theinitial CD4⁺ T cell-rich population enabledefficient induction of the autologous CTL in theensuing trials. The CTL thus generated exhibitedstronger killing activities against autologous braintumor cells and ovarian tumor cells than previouslyobserved. This simple recycling of the primed butinert CD4⁺ T cell-rich population for CTLinduction will promote clinical practice of adoptiveimmunotherapy of human tumors with autologous CTL.     

Preliminary observations of spawning behavior of white-streaked grouper (Epinephelus ongus) in an Okinawan coral reef

Epinephelus ongus forms spawning aggregations at specific reef sites at Okinawa. The aim of the present study was to describe the spawning behavior of E. ongus based upon underwater video imagery. Epinephelus ongus spawning is usually paired with courting males and females rushing upwards towards the surface during the spawning ascent, with a subsequent release of eggs at the apex of the ascent. In two of four spawning events we observed, however, the ascending pair was joined by additional males. Fish eggs collected at the site were identified as those of E. ongus and confirmed that this species spawns mainly at night during a slack tide. This study is the first documentation of E. ongus spawning behavior in the field.