Characteristics of alpha-glucosidase production from recombinant Aspergillus oryzae by membrane-surface liquid culture in comparison with various cultivation methods

alpha-Glucosidase was produced using recombinant Aspergillus oryzae by membrane-surface liquid culture (MSLC), a method previously developed by the authors and the results compared with other methods, including shaking flask culture (SFC), agar-plate culture (APC), culture on urethane sponge supports (USC), and liquid surface culture (LSC) to determine possible reasons for the advantageous features of MSLC. When yeast extract was used as a nitrogen source, the amount of enzyme produced by MSLC was 5 or more times higher than those for SFC and LSC, but similar to that using APC. Enzyme production in USC was slightly lower than in MSLC and APC. Cell growth was similar irrespective of the cultivation method used. When NaNO3, a typical inorganic nitrogen source was used, enzyme production in all the cultures was lower than that using yeast extract. However, even using NaNO3, the amount of the enzyme produced by MSLC was 8 to 20 times higher than those by SFC, APC, USC, and LSC. Although cell growth using NaNO3 was similar to that for yeast extract in MSLC, it was markedly decreased in SFC, APC, and LSC. The reason for the difference in enzyme productivity for various cultivation methods using yeast extract and NaNO3 as a nitrogen source is discussed, on the basis of the experimental findings. The role of the oxygen transfer effect and gene expression levels in enzyme production were also examined.     

2 Gbit/s small form factor fiber-optic transceiver for single modeoptical fiber

Small form factor (SFF) optical transceivers are expected to be commonly used in the near future for high-end (high bit-rate, single mode) applications as well as for low-cost applications. SFF optical transceivers require new packaging techniques for the optical portion, because the distance between input and output optical axes is much smaller than those of conventional transceivers, e.g., the “1by9” type. Two types of optical packaging are introduced, both of which are suitable for transceivers which have an MT-based receptacle for single mode applications. One of the packaging types, a fiber-bulk structure, takes full advantage in cost and reliability of standard, hermetically sealed TO-canned optical devices. A conventional TO-can packaged laser diode (LD) and photodiode (PD) are held with short optical fibers by low-cost, injection-molded polymer retainers. The short fibers are connected to an MT ferrule inside the transceiver. An alternative packaging type, a surface mount structure, is intended for drastic cost reduction in large volume production by using advanced highly integrated assembly. An LD chip with an integrated spot-size converter and a waveguide-structured PD chip are mounted on a Si-substrate. Optical coupling between the optical devices and fibers on V-groove is accomplished by passive alignment, which reduces assembling time. A prototype transceiver with an MPO receptacle has been developed using the former packaging structure. Evaluated results show performance which complies with the 2.125 Gbit/s Fiber Channel standard. SFF transceivers with these new packaging technologies are expected to increase the optical port density and also to reduce the cost of high-end systems with bit rate of 2 Gbit/s or higher per port     

Neuroimmunological Implications of AQP4 in Astrocytes

The brain has high-order functions and is composed of several kinds of cells, such as neurons and glial cells. It is becoming clear that many kinds of neurodegenerative diseases are more-or-less influenced by astrocytes, which are a type of glial cell. Aquaporin-4 (AQP4), a membrane-bound protein that regulates water permeability is a member of the aquaporin family of water channel proteins that is expressed in the endfeet of astrocytes in the central nervous system (CNS). Recently, AQP4 has been shown to function, not only as a water channel protein, but also as an adhesion molecule that is involved in cell migration and neuroexcitation, synaptic plasticity, and learning/memory through mechanisms involved in long-term potentiation or long-term depression. The most extensively examined role of AQP4 is its ability to act as a neuroimmunological inducer. Previously, we showed that AQP4 plays an important role in neuroimmunological functions in injured mouse brain in concert with the proinflammatory inducer osteopontin (OPN). The aim of this review is to summarize the functional implication of AQP4, focusing especially on its neuroimmunological roles. This review is a good opportunity to compile recent knowledge and could contribute to the therapeutic treatment of autoimmune diseases through strategies targeting AQP4. Finally, the author would like to hypothesize on AQP4’s role in interaction between reactive astrocytes and reactive microglial cells, which might occur in neurodegenerative diseases. Furthermore, a therapeutic strategy for AQP4-related neurodegenerative diseases is proposed.     

Enzymatic assay method for measuring mizoribine levels in serum

A sensitive and specific method for assaying serum mizoribine levels that can be applied to general automatic clinical analyzers was developed. Regression analysis of the enzymatic assay (y) vs. the HPLC method (x) produced the following relation: y=0.964x+0.090 (n=262, Sy, x=6.37 ng/mL).     

Resveratrol derivative-rich melinjo (Gnetum gnemon L.) seed extract suppresses multiple angiogenesis-related endothelial cell functions and tumor angiogenesis

Angiogenesis is a promising target for cancer prevention and treatment. This study aimed to determine the antiangiogenic effects of melinjo (Gnetum gnemon L.) seed extract and its resveratrol derivative components, such as gnetin C (GC), gnetin L (GL), gnemonoside A (GMA), gnemonoside C (GMC), and gnemonoside D (GMD). An ethanol extract of melinjo seeds (EEMS) and the two gnetins markedly inhibited the proliferation and tube formation of human umbilical vein endothelial cells (HUVEC) stimulated with vascular endothelial growth factor and basic fibroblast growth factor. The inhibitory effects of GC and GL were much stronger than those of resveratrol. GMC and GMD inhibited only proliferation, whereas GMA had almost no effect on the two endothelial cell functions. The EEMS and GC also reduced the cell viability of tube-forming HUVEC, with accompanying ERK1/2 inactivation, and suppressed the migration of HUVEC. Furthermore, dietary intake of EEMS significantly inhibited tumor angiogenesis in a mouse dorsal air sac assay. In conclusion, we found that the EEMS and its resveratrol derivatives, particularly GC, suppress multiple angiogenesis-related endothelial cell functions and/or tumor angiogenesis, indicating that the melinjo seeds and the natural resveratrol derivatives may be useful for cancer prevention and treatment.     

A computational model for distributed knowledge systems with learning mechanisms

This paper addresses the issues of machine learning in distributed knowledge systems, which will consist of distributed software agents with problem solving, communication and learning functions. To develop such systems, we must analyze the roles of problem-solving and communication capabilities among knowledge systems. To facilitate the analyses, we propose a computational model: LPC. The model consists of a set of agents with (a) a knowledge base for learned concepts, (b) a knowledge base for problem solving, (c) prolog-based inference mechanisms and (d) a set of beliefs on the reliability of the other agents. Each agent can improve its own problem-solving capabilities by deductive learning from the given problems, by memory-based learning from communications between the agents and by reinforcement learning from the reliability of communications between the other agents. An experimental system of the model has been implemented in Prolog language on a Window-based personal computer. Intensive experiments have been carried out to examine the feasibility of the machine learning mechanisms of agents for problem-solving and communication capabilities. The experimental results have shown that the multiagent system improves the performance of the whole system in problem solving, when each agent has a higher learning ability or when an agent with a very high ability for problem solving joins the organization to cooperate with the other agents in problem solving. These results suggest that the proposed model is useful in analyzing the learning mechanisms applicable to distributed knowledge systems.     

Comparative nutritional value for amino acids,oligopeptides and soybean protein

In recent years our view on the absorption of protein digestion products has undergone a radical change. We now believe that intralumen hydrolysis of intake proteins to free amino acids is only partial. It has thus been hypothesized that partial protein hydrolysates or oligopeptide mixtures are nutritionally superior to corresponding amino acid mixtures. With this consideration for a background, we developed a sophisticated technique of protease-catalyzed modification of soy protein to produce enzymatically modified proteins (EMP) having different levels of covalently attached methionine. We also carried out feeding tests with protein-malnourished rats, with the result that for their recovery from a state of malnutrition, an EMP containing peptide-bound methionine at 3% was significantly more effective than the corresponding amino acid mixture and even the soy protein itself. Discussions stress the importance of applying such a technique to production of an oligopeptide rather than a free amino acid nitrogen source as a foodstuff for therapeutic use.