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Contents:  We present a design for a dispersion managed (DM) soliton system, which is based on two primary parameters; the dispersion compensation period (DCP), which is defined by the number of DSF spans between dispersion compensation fiber, and pulse width. We designed the optimum value of these two parameters to achieve the widest system margins for both repeater output power and signal wavelength for trans-oceanic distance transmission. We checked this analysis by experiments for both 10 and 20 Gb/s DM soliton systems having 53 km repeater spacing. Experimental results confirm the validity of proposed system design.

Summary: Fourier transform and an image filtering technique were used for structural analysis of the pellicular strip inEuglena gracilis. Freeze-fracture images of a two-dimensional crystalline structure in the plasma membrane were taken from elongated and rounded cells. Their lattice constants were precisely determined from Fourier transform patterns, and masked filter images were generated. Although differences in their lattice constants could not be detected, the Fourier transform patterns showed a significant difference between these two stages of cell shape. In elongated cells, the pseudo-crystal lattice was generated in the half periodicity of the minor striation. In contrast, it disappeared when the cells became rounded. The filtered images confirmed the crystallographic disagreement between these two stages in cell shape, probably reflecting morphological changes of integrated plasma membrane particles. Four particles detected in a unit structure showed quite similar shapes across the pseudo-lattice in elongated cells, though a unit structure in rounded cells consisted of four heterogeneous particles with opaque boundaries. A 39 kDa integral plasma membrane protein (IP39) is known as a major component in the plasma membrane ofE. gracilis. The compositions of monomeric and oligomeric forms of IP39 were determined in both elongated and rounded cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, which showed the possibility that an oligomerization of IP39 proceeds during rounding-up movement of the cell. These morphological and stoichiometrical changes of the integrated plasma membrane proteins may suggest an active involvement in cell shape change.

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FtsH protein in Escherichia coli is an essential protein of 70.7 kDa (644 amino acid residues) with a putative ATP-binding sequence. Western blots (immunoblots) of proteins from fractionated cell extracts and immunoelectron microscopy of the FtsH-overproducing strain showed exclusive localization of the FtsH protein in the cytoplasmic membrane. Most of the FtsH-specific labeling with gold particles was observed in the cytoplasmic membrane and the adjacent cytoplasm; much less was observed in the outer membrane and in the bulk cytoplasm. Genetic analysis by TnphoA insertions into ftsH revealed that the 25- to 95-amino-acid region, which is flanked by two hydrophobic stretchs, protrudes into the periplasmic space. From these results, we concluded that FtsH protein is an integral cytoplasmic membrane protein spanning the membrane twice and that it has a large cytoplasmic carboxy-terminal part with a putative ATP-binding domain. The average number of FtsH molecules per cell was estimated to be approximately 400.

Summary Effects of cycloheximide (CHM) on preprophase bands (PPBs) of microtubules (MTs) and on prophase spindle MTs in root tip cells of onion (Allium cepa L.) were examined. When root tip cells were treated with 36 µM CHM for 0.5–4 h, the population of cells with a PPB did not decrease markedly although the population of mitotic cells and that of prophase cells with a PPB gradually decreased to half of the control root tips. In prophase cells treated with 11 and 36 µM CHM for 2 h, the width of the PPB was 1.4 times broader than that in the prophase PPB without CHM. Electron microscopic observation on the cross section of the PPB showed that the number of MTs and the distance between adjacent MTs in prophase PPBs treated with CHM were similar to those in the early developmental stage of PPBs without CHM. The bipolar spindle, that appeared in late prophase was not seen in prophase cells treated with 11 µM or higher concentrations of CHM for 2 h. In order to examine differences of perinuclear MT arrangement between CHM treated and non-treated prophase cells, arrangement of perinuclear MTs was examined by confocal laser scanning microscopy. In control cells without CHM, MTs appeared on the nuclear surface with several “branched” or “cross over” type MT foci in the cytoplasm when broad PPB formation started. These MT foci were replaced by the “aster” type MT foci, from which several MTs radiated along the nuclear surface. The “aster” type MT foci gradually gathered to form a bipolar spindle. MTs connecting the spindle pole region and the PPB were seen in late prophase. In CHM-treated cells (11-360 µM for 2 h), “branched” and “cross over” type MT foci were prominent, even in prophase cells with well condensed chromosomes. Neither linkages of MTs between the spindle pole region and the PPB nor “aster” type MT foci were seen. These observations showed that CHM prevents the bundling of MTs in the PPB and also inhibits the formation of “aster” type MT foci that is essential for bipolar spindle development.

Summary Changes in intracellular pH (pHi) have been examined during zoosporogenesis inPhytophthora cinnamomi in order to elucidate the molecular mechanisms that bring about initiation of the orderly cleavage of the sporangium. By microinjecting a dextranconjugated pH-sensitive fluorescent indicator, 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF dextran), and using fluorescence ratio image analysis, the pHi of a sporangium was monitored throughout the process of zoosporogenesis. The pHi of mature sporangia was found to remain constant at pH 6.84 ± 0.05 (mean ± SE, n=6) at room temperature (24 °C), but increased to 7.04 ± 0.04 (p < 0.001) during a 20 min cold treatment at 19 °C. As the process of zoosporogenesis proceeded, the increased level of pHi was maintained for 30–40 min after initiation of the cold shock. Zoosporogenesis was blocked when the pHi of the sporangium was held constant by microinjecting with 10 mM HEPES buffer (pH 7.0) before cytoplasmic cleavage was induced by a cold shock. In contrast, no inhibitory effect was observed when sporangia were microinjected with HEPES buffer after the cold shock. These results indicate that initiation of cytoplasmic cleavage requires a rise in pHi.

A free-space optical interconnection scheme is described for massively parallel processors based on the interconnection-cached network architecture. The optical network operates in a circuit-switching mode. Combined with a packet-switching operation among the circuit-switched optical channels, a high-bandwidth, low-latency network for massively parallel processing results. The design and assembly of a 64-channel experimental prototype is discussed, and operational results are presented.

Detergent-extracted cell models of the euglenoid flagellate, Astasia longa, were obtained that rounded-up on addition of calcium. Treatment with 4% Triton X-100 and Nonidet P-40 removed the flagellar membrane, all membranous structures inside the cell body and the plasma membrane at groove regions of the cell surface. Maximum rounding-up was induced when the concentration of free calcium was raised to ≥10−7M, and ATP strongly enhanced this response. The ionic requirements and sensitivity to vanadate were different from those for the reactivation of flagellar movement. The results suggest that the mechanism of force generation is different from the dynein-based system of the flagellum and that a rise in cytoplasmic free Ca2+ concentration might cause euglenoid movement in vivo. The mechanism of euglenoid movement is discussed in relation to other protozoan motile systems.

Using its microtubule-containing axopodia, a heliozoan Echinosphaerium nucleofilum feeds on various kinds of protozoans and small metazoans. The present study revealed that food capture and ingestion were carried out in 2 different ways or by a combination of them. The first one was by the rapid contraction of axopodia, by which the food organism was conveyed directly toward the body surface. After such a contraction, many of the microtubules which had been present inside the axopodia degraded and were replaced by C-shaped microtubules. Bundles of tubular bodies were also detected alongside the axonemal microtubules, especially following the use of glutaraldehyde fixative containing ruthenium red. The second method was by means of axopodial flow, by which a food organism attached to an axopodium was conveyed to the body surface along the axopodial surface without accompanying axopodial degradation or contraction. Subsequently the food organism was surrounded by several small pseudopodia to form a food vacuole; many filamentous structures (5–10 nm in diameter) were observed inside the pseudopodia. During the ingestion process many cytoplasmic extensions, including rosary-like filaments, were observed to protrude from the contracted axopodia and the cell body. Mottled dense granules were observed to be discharged from the axopodial surface just when the prey was captured.

Summary InEuglena fusca, each pellicular strip carries a row of particles on its surface. The relative displacement of particles on adjacent strips was analysed by video-microscopy and evidence was obtained that adjacent pellicular strips slide relative to each other during euglenoid movement.E. fusca shows two types of euglenoid movement, oscillatory bending and rounding-up of the cell body. During oscillatory bending, the maximum velocity of sliding was 0.4 µm/s and the maximum displacement distance between adjacent strips 2.3 µm about their mean position. WhenE. fusca exhibited rounding-up of the cell body, particle displacement again occurred and the angle of the pellicular strips to the long axis of the cell body increased because of pellicular sliding. As a result the distance between the cell's anterior and posterior tips was reduced. There was no change in distance either between rows of particles or between particles within the same row. The findings are incompatible with theories of euglenoid movement requiring local contraction of pellicular strips and point to the likely existence of active sliding between adjacent strips.

A high speed receiver module has been developed for 10 Gbit/s optical transmission systems. To achieve a wideband module, a 12.7 GHz bandwidth AlGaAs/GaAs HBT preamplifier IC and an impedance matched package were used. The receiver sensitivity at 10 Gbit/s is −15.7 dBm, and is −30.3 dBm with an optical preamplifier.

A high-sensitivity optical receiver has been developed with a low-noise, large gain-bandwidth product superlattice APD. Minimising the front-end circuit noise has realised the highest receiver sensitivity of −27.6dBm at 10Gbit/s operation ever reported for the APD receivers.

High-performance, long-wavelength OEICs on a GaAs-on-InP heterostructure were fabricated. For the transmitter OEIC, high-speed operation up to 2.4 Gbit/s was achieved, and a receiver sensitivity as high as −26.0 dBm for a 1.2 Gbit/s NRZ signal was realised for the receiver OEIC. To confirm the usefulness of these OEICs for optical fibre networks, a 1.2 Gbit/s optical fibre transmission experiment was successfully carried out over a 52.5 km span.

A multi-Gbit/s transmitter module with a high-speed hetero-MISFET driver IC and a multi-quantum-well DFB-LD has been developed. A miniaturised module with bare chip mounting of the LD and the driver IC made 10 Gbit/s high-speed operation possible. Using this module, an optical fibre transmission experiment has been successfully carried out over 40 km.

A 5 Gbit/s optical receiver module was developed by using a wideband transimpedance Si IC and a high gain-bandwidth product GaInAs APD. A 6 GHz bandwidth Si IC utilising a f1 = 20 GHz Si MMIC process, bare chip mounting of a Si IC and an APD to minimise parasitic capacitance, made it possible to realise high speed operation and high receiver sensitivity of −31.8 dBm.

A GaAs-on-InP long wavelength OEIC receiver, with a monolithically integrated three-stage preamplifier, was designed using SPICE and fabricated. The three-stage OEIC receiver exhibited excellent performances, such as −32.5 dBm receiver sensitivity and 85 dBΩ transimpedance at 600 Mbit/s. These results indicate the feasibility of integrating large scale electronic circuits, which are considered as the OEIC merits, caused by using both GaAs-on-InP heterostructures and SPICE.

The feasibility of 10 Gbit/s transmission has been confirmed through zero power-penalty transmission over a 100 km dispersion-shifted optical fibre, employing a high-speed, small chirping MQW DFB-LD and a high quantum efficiency back-illuminated GaInAs APD.

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