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Anemonefish, including the false clownfish Amphiprion ocellaris, are attractive model organisms because of their unique features, such as sex change and brilliant color patterns in mutants. However, anemonefish are not widely used to study gene function using reverse genetic approaches owing to microinjection difficulties and subsequent rearing and hatching of embryos without parental care. A. ocellaris embryos are spawned on a hard substrate and cared for by their parents until hatching. However, the eggs need to be detached from the substrate and raised without their parents to perform successful microinjection. We established a method to culture and hatch A. ocellaris embryos without spawning substrates or parental care. We found that changing water and generating water flow are critical for culturing the embryos, and that water flow (as physical stimulation) and complete darkness in the dark period are necessary for successful hatching. We further investigated the effectiveness of microinjection into the yolk sac of fertilized eggs rather than into the cytoplasm, which makes microinjection easier. A reporter RNA injected into the yolk sac was transferred to the cytoplasm and translated, indicating that yolk sac microinjection is an efficient alternative as has been used for zebrafish. These findings highlight the potential of A. ocellaris as an experimental model organism for reverse genetics, and our methods could be applied to other anemonefish species. [ABSTRACT FROM AUTHOR]

Natural antifouling products have been the subject of considerable attention. We screened marine algae for antifouling activity and discovered omaezallenes, the new bromoallene-containing natural products isolated from the red alga Laurencia sp. Described is the isolation, structure elucidation, and total syntheses of omaezallenes. The relative and absolute configurations of natural omaezallenes were unambiguously established through total synthesis. The antifouling activities and ecotoxicity of omaezallenes were also evaluated. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to examine the potential use of defatted soybean meal (SBM) and freeze-dried meat of blue mussel (BM) as partial replacement of fish meal in the diet of tiger puffer. Eight experimental diets were formulated, in which 0, 20, 40 and 60% fish meal protein were replaced with SBM (S0B0, S20B0, S40B0, and S60B0), and 40 and 60% with a combination of SBM and BM (S30B10, S20B20, and S45B15, S30B30). Fish of 11 g initial body weight were fed the diets to satiation twice daily, 6 d/wk for 8 wk at 20 C. Specific growth rate, feed efficiency, and protein efficiency ratio (PER) of fish fed diets containing SBM as an alternative protein source for fish meal decreased with increasing level of SBM, and these parameters of fish fed S40B0 and S60B0 diets were significantly lower than those of the control. Growth of fish in dietary groups containing BM were statistically identical to those in the control, and tended to increase with increasing level of dietary BM both at 40 and 60% substitution levels. Growth and feed utilization of fish fed S20B20 were almost the same to those in the control. [ABSTRACT FROM AUTHOR]

The acute toxicities of copper were examined for Japanese flounder, Paralichthys olivaceus, and red sea bream, Pagrus major, in terms of fish size and water temperature. Artificial seawater of low pH of 5.4–6.7 was used as testing water to keep dissolved copper concentration at 0.04–41 mg Cu/L. Japanese flounder of 0.3–17 g and red sea bream of 0.5–13 g were exposed to different concentrations of copper for 96 h at 20 C under semistatic condition. Median-lethal concentration for 96 h of Japanese flounder and red sea bream were 8.7–12.2 and 2.0–5.2 mg Cu/L, respectively. No significant relationships were observed between median-lethal concentrations for 96 h and fish size for Japanese flounder, while the value decreased significantly with increasing fish size for red sea bream. Effect of water temperature on the acute toxicity was examined for Japanese flounder of 0.3 and 0.4 g at 10, 15, 20, and 25 C and red sea bream of 0.5 and 1.0 g at 12, 15, 20, and 25 C. Ninety-six-hour median-lethal concentrations for Japanese flounder and red sea bream were 5.1–11.2 and 1.0–5.3 mg Cu/L, respectively. No significant relationships were observed between median-lethal concentrations for 96 h and water temperature for both fish species. [ABSTRACT FROM AUTHOR]

Two 12-wk rearing experiments were conducted to examine the effect of rearing salinities of 10–35 ppt on the growth of 3- and 170-g-size tiger puffer, Takifugu rubripes. Fish were reared in a closed recirculation system without introducing fresh culture water at 23 C and were fed commercial pellet diet for tiger puffer twice or three times daily to apparent satiation each, almost everyday. Growth of 3-g-size fish seemed to increase with decreasing salinity; however, there were no significant differences in the specific growth rate and weight gain among treatments because of differences in initial body weight. Final body weight and length of fish reared at 10 ppt were significantly higher than those for fish reared at 30 ppt although initial sizes were similar. Differences were not found for the feed efficiency (FE) and daily feed consumption. Apparent relationships were not observed between salinity and blood characteristics or proximate compositions of muscle of the cultured fish. Differing from smaller fish, growth of 170-g-size fish tended to decrease with decreasing salinity from 30 to 10 ppt and with increasing salinity from 30 to 35 ppt. Similar trends for FE were observed. [ABSTRACT FROM AUTHOR]

The distribution of stress during drying of fresh Japanese noodle (udon) was investigated by mathematically modelling the changes in shrinkage and other mechanical properties, this allowed crack formation to be predicted. It was observed that the shrinkage coefficients were nearly the same in all three directions with changing moisture content, and the degree of shrinkage was independent of the temperature. The Young's modulus, yield stress and fracture stress could be expressed as exponential functions of moisture content. Changes in stress distribution during drying were calculated by coupling the moisture transfer equation with the constitutive equation using a finite element method. The calculated stress distribution indicated that a rapid drying rate causes extensive internal tensile stress in udon. The scheme used in the present study was found to effectively represent the potential for crack formation along the central axis, this was shown to be consistent with the actual cracking pattern. [ABSTRACT FROM AUTHOR]

Although the π/4 phase shift modulation schemes used in quadrature phase shift keying (QPSK) are important approaches to ensuring efficient frequency usage in digital portable telephone systems, they also require linearity of the power amplifiers, they also require linearity of the power amplifiers, which is an undesirable constraint from the standpoint of efficiency. In this work, we describe a unified approach to this problem based on the idea that distortion can be effectively decreased by creating dips or “bumps” in the intermod characteristics, due to the dependence of the adjacent channel power (ACP) leakage on input power. For the special case of an impedance Zes connected to the gate of a FET, we use Volterra series to quantitatively demonstrate how the appearance of such dips or bumps is related both to Zes and to the fifth intermod (IM5). We then show analytically that when these dips or bumps are generated effectively, they can suppress IM5. Finally, we show that the resulting decrease in intermodulation distortion and improved efficiency make this method useful in the design of MMIC power amplifiers used in Personal Handy Phone (PHS) service. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(4): 10–21, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1100 [ABSTRACT FROM AUTHOR]