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This research focuses on the multiphase oil film tribology between the piston pin and the connecting rod in an internal combustion engine and establishes a new computational approach for thin-film lubrication with unsteady flow channel variation. First, the pin and the connecting rod are considered as rigid bodies, and 3D numerical analysis of the cavitating lubricating oil flow is performed when combustion load is applied to the pin. We find that dynamic pressure does not increase around the connecting rod edge and that pressure is potentially insufficient to support the load. In the second numerical analysis, the pin and the connecting rod are considered to be elastically deformable structures, and coupled 3D multiphase fluid–structure interaction simulation is performed. The boundary lubrication area is detected using a statistical Greenwood–Tripp model as unevenness of the contacted metal surface. The results show that pressure distribution spreads more widely than in the result for rigid bodies and that the film was thicker as well. Also, the pin deformed like a bow, but the deformation of the connecting rod was quite small, suggesting a potential mechanical contact at the edge of the connecting rod with the pin. By comparison with an actual operationally used piston pin, we find that the fluid–structure coupled analysis qualitatively predicted the seizure location.

Coral symbionts are important members of the coral holobiont, and the coral bacterial flora is essential in host health maintenance and coral conservation. Coral symbionts are affected by various environmental factors, such as seawater temperature, pH, and salinity. However, the effect of communication between different coral species and water flow against coral bacterial flora on its community structure is not well understood. In this study, we designed an artificial rearing environment to examine the impact of environmental and biological factors on Acropora tenuis, one of the major coral species in Okinawa, and Montipora digitata, from their co-culture. We intervened with the water flow to reveal that the movement of the rearing environment alters the bacterial flora of A. tenuis. During the bacterial community reconstruction, the alpha diversity of the coral microbiota increased, suggesting the establishment of rare bacteria from the ocean. No differences in the bacterial composition between the control and water flow groups were observed under the rearing conditions. However, the structure of the bacterial flora was significantly different in the co-culture group. Comparison among each bacterial community succession strongly suggest that the difference was due to the suppressed transmission of bacteria from the ocean in the co-culture group. These results contribute to the understanding of communication between corals and shed light on the importance of regional differences and bacterial composition of coral flora.

Coral symbionts are important members of the coral holobiont, and coral bacterial flora are essential in host health maintenance and coral conservation. Coral symbionts are affected by various environmental factors, such as seawater temperature, pH, and salinity. Although physicochemical and chemical factors have been highlighted as possible causes of these effects, the effects of water flow and the co-culture of different species corals have not been elucidated. In this study, we designed an artificial rearing environment to examine the impact of environmental and biological factors on Acropora tenuis, one of the major coral species in Okinawa, and Montipora digitata, during their co-culture. We intervened with the water flow to reveal that the movement of the rearing environment alters the bacterial flora of A. tenuis. During the rearing under captive environment, the alpha diversity of the coral microbiota increased, suggesting the establishment of rare bacteria from the ocean. No differences in the bacterial composition between the control and water flow groups were observed under the rearing conditions. However, the structure of the bacterial flora was significantly different in the co-culture group. Comparison of bacterial community succession strongly suggested that the differences observed were due to the suppressed transmission of bacteria from the ocean in the co-culture group. These results enhance our understanding of interactions between corals and shed light on the importance of regional differences and bacterial composition of coral flora.

Most reef-building corals are hermaphroditic and discharge buoyant bundles that contain a mixture of eggs and spermatozoa during the breeding season. The buoyancy of the bundles is due to wax-ester...

Corals create an ecosystem, called a holobiont, with intracellular algae (zooxanthellae) and resident bacteria. Zooxanthellae and some bacteria play major roles in the physiological properties of the coral host. However, because of the difficulties in experimental verification of cross-organism interactions, the mechanisms underpinning these interactions are largely unknown. To address this, we here generated and then analyzed multi-omics datasets for corals, zooxanthellae, and bacteria collected at Okinawa, Japan, from November 2014 to September 2016. Using cross-organism co-expression analysis, we successfully characterized the host–alga relationship in the coral holobiont. Specifically, we observed that the coral host dominates the zooxanthellae. The multi-omics analysis also suggested that infection with coral-associated bacteria Endozoicomonas likely involves coral-like ephrin ligands, triggering an immune response of the coral host. This study highlights the potential of the multi-omics approach to elucidate coral–microbe interactions.

Many corals establish symbiosis with Symbiodiniaceae cells from surrounding environments, but very few Symbiodiniaceae cells exist in the water column. Given that the N-acetyl-D-glucosamine-binding lectin ActL attracts Symbiodiniaceae cells, we hypothesized that corals must attract Symbiodiniaceae cells using ActL to acquire them. Anti-ActL antibody inhibited acquisition of Symbiodiniaceae cells, and rearing seawater for juvenile Acropora tenuis contained ActL, suggesting that juvenile A. tenuis discharge ActL to attract these cells. Among eight Symbiodiniaceae cultured strains, ActL attracted NBRC102920 (Symbiodinium tridacnidorum) most strongly followed by CS-161 (Symbiodinium tridacnidorum), CCMP2556 (Durusdinium trenchii), and CCMP1633 (Breviolum sp.), however, it did not attract GTP-A6-Sy (Symbiodinium natans), CCMP421 (Effrenium voratum), FKM0207 (Fugacium sp.), and CS-156 (Fugacium sp.). Juvenile polyps of A. tenuis acquired limited Symbiodiniaceae cell strains, and the number of acquired Symbiodiniaceae cells in a polyp also differed from each other. The number of Symbiodiniaceae cells acquired by juvenile polyps of A. tenuis was correlated with the ActL chemotactic activity. Thus, ActL could be used to attract select Symbiodiniaceae cells and help Symbiodiniaceae cell acquisition in juvenile polyps of A. tenuis, facilitating establishment of symbiosis between A. tenuis and Symbiodiniaceae cells.

Rickettsiales-like organisms are important for the survival and functioning of corals, prompting an investigation of their complete genomes. Earlier reports of the genomes of these organisms remain incomplete. Here, we report a novel draft genome of Rickettsiales bacterial strain SESOKO1, found in Acropora tenuis coral, using single-cell genome technology.

Rickettsiales -like organisms are important for the survival and functioning of corals, prompting an investigation of their complete genomes. Earlier reports of the genomes of these organisms remain incomplete. Here, we report a novel draft genome of Rickettsiales bacterial strain SESOKO1, found in Acropora tenuis coral, using single-cell genome technology.

In high-pressure die casting, attention has been paid to the J factor, which is defined by the speed of the metal injected at the gate and the shape of the gate. In casting experiments using a piston die, the porosity of the product can be reduced by increasing the J factor such that the metal flow passing through the gate forms an atomized flow. To clarify the underlying mechanisms, we developed a system for simulating a two-phase flow of air and aluminum by large-scale calculations of turbulent flow. During the development of the system, we injected metal into an open space and performed imaging to confirm the state of the atomized flow. The system was then verified by reproducing the atomized flow. The analysis results visualized the many small turbulent vortices generated in the thick part far from the gate. We demonstrated that the change from small to longitudinal vortices promoted entrainment of air into the aluminum and increased the efficiency of air expulsion outside the die through an increase in the J factor.

World production of plastic has dramatically increased from the 1950's and now it reaches approximately 311 million tons per year. The resulting accumulation of small plastic detritus less than 5 mm in size, termed “microplastics”, has started threatening the life cycles of marine organisms. Here we show the first evidence that microplastics disturb the initiation of symbiotic relationships in anthozoan-algae symbiosis. We found in both the aposymbiotic sea-anemone Aiptasia sp. and the coral Favites chinensis that the infectivity of symbiotic algae into the host is severely suppressed by microspheres fed either directly or indirectly through microsphere-fed Artemia sp. Similar trends were seen when microplastics collected from commercial facewash were used instead of microspheres. Therefore, ongoing accumulation of microplastics in the ocean might disturb the healthy anthozoan-algae symbiotic relationships, which are cornerstones of the biologically enriched coral reef ecosystem.

Okinawa is the southwesternmost part of Japan and represents the northern limit of coral reefs that are influenced by the Kuroshio warm current. We have been studying two coral reefs off Sesoko Island, in northern Okinawa, to evaluate coral reef environments since 2014. In this study, we applied a metagenomic approach to analyze the seasonal composition of picophytoplankton at these two reef sites (Sesoko Minami and Ishikawabaru). The two sites were selected for their differences: Sesoko Minami faces the open ocean and experiences relatively small land effects, while Ishikawabaru experiences relatively high land effects and is surrounded by barrier reefs. Seawater samples were collected from these two sites and filtered through a 1.6 μm pore filter followed by a 0.2 μm membrane filter. DNA was extracted from the 0.2 μm filters, and the V1-V2 region of the 16S rRNA gene (260 bp) was amplified before sequencing using next-generation sequencing techniques. Cyanobacteria or chloroplast sequences were selected for further metabarcording analyses. Interestingly, almost no differences were indicated between the two sites and more than 95% of the picophytoplankton at both sampling sites was composed of only 5 to 7 OTUs. The seasonal composition of picophytoplankton clearly changed; in summer (Jul 2014, May to Jul 2015, and May to Aug 2016) OTU 1 (Synechococcus sp. NC007513) was most abundant. OTU 4 (Prochlorococcus marinus NC009091) also reached its maximum abundance in summer (May to Aug 2016), while OTU 6 (Bathycoccous prasinos FN563099) increased in winter. OTU 8 (Micromonas commoda RCC299 FJ858267) was present at every sampling period and accounted for 5–20% of the total picophytoplankton contig numbers. Our results indicate that seasonal changes clearly influence fluctuations in picophytoplankton community compositions.

Previous studies have suggested that blastomeres from the 2-, 4-, or 8-cell stage of corals have the ability to develop into normal primary polyps. However, it is still not known which developmental stage’s blastomere produces which juvenile. In this study, we demonstrated that only the blastomeres with animal hemispheres have the capacity to develop into normal primary polyps. Individuality was evaluated using blastomeres isolated from the corals Acropora digitifera, A. intermedia, Dipsastraea lizardensis, and Favites chinensis. On commencement of embryo cleavage, the animal pole was marked using Neutral red staining, and at the 2-, 4-, and 8-cell stages, embryos were divided into individual blastomeres using glass needles. We found that the survival rate and percentage metamorphosis were higher in the larger-sized blastomeres with animal hemispheres. The vegetal hemisphere alone is incapable of developing into a normal primary polyp; however, a ball-shaped embryo with incomplete mesenteries and no pharynx developed in some cases. These results indicate that the animal hemisphere is needed for corals to develop into normal primary polyps, and that the individuality of corals is possibly determined by a combination of the chance physical splitting of embryos by waves and their innate developmental ability.

Approximately 20 major-to-ultratrace elements in each organ (mantle, muscle, liver, kidney) of a giant clam, Tridacna crocea, and 16 elements in symbiotic zooxanthellae were determined by ICP-AES, ICP-MS, and CHN coder. The biogeochemical properties of T. crocea were then investigated using multi-element profiling analyses. The values for most elements were the highest in the kidney among all organs. However, the concentrations of Mn, Co, Ni, Zn, Se, Ag, Cd, and Pb in the mantle were higher than those in the muscle and liver. Therefore, these results indicate that most trace elements taken in by T. crocea through zooxanthellae may finally accumulate in the kidney. Moreover, 14 trace elements in zooxanthellae were present in the concentration range from 181 µg g−1 for Zn to 0.58 µg g−1 for U based on dry weight after isolating zooxanthellae from the mantle. The concentrations of some trace metals in zooxanthellae were relatively higher than those in other organs except for the kidney. These results suggest...

Corals harbor symbiotic dinoflagellates, Symbiodinium spp., acquired from surrounding environments. Because Symbiodinium are present at low densities in the water column, corals may attract these symbionts using chemotactic compounds. To examine whether corals contain chemotactic compounds, we established an assay to measure the chemotactic activity for Symbiodinium using an extract of the coral Acropora tenuis, a major reef-building coral in Japan. Our assay revealed that Symbiodinium strain NBRC102920 (clade A), which is taken up by juvenile A. tenuis polyps, is attracted to crude A. tenuis extracts. We found that the chemotactic compounds are water-soluble, heat-labile macromolecules and that the chemotactic activity was inhibited by N-acetyl-d-glucosamine (GlcNAc). We separated the GlcNAc-binding fraction (Fr-ActL) and identified it as the most plausible candidate for the chemoattractant, since the chemotactic activity of the crude A. tenuis extract appeared to be mainly attributable to the activity of Fr-ActL and was also inhibited by the addition of GlcNAc. These results indicate that chemoattraction is mediated via the binding of Symbiodinium to Fr-ActL.

The present study applied multi-element profiling analysis to the monitoring of coastal seawater around coral reefs to elucidate the elemental characteristics and the biogeochemical cycles. In temporal concentration variation, the long-term monitoring (monthly over one year) and short-term monitoring (3-hourly over two days) were subjected to multi-element determination by ICP-MS with solid phase extraction using chelating resin. In the long-term monitoring, the nutrient-type elements Fe, Ni, Cu, Zn, and Cd and the scavenging-type elements Mn, Co, and Pb showed wide variations in their total, dissolved, and acid-soluble concentrations. The elevated total concentrations of Mn, Fe, Ni, Cu, Zn, Cd, and Pb in short-term variation of October 2011 were possibly caused by mucus secreted from coral. The increased concentrations of trace metals in the coastal seawater around the reefs might play important role to provide bio-essential trace metals to zooxanthellae living in symbiotic animals, such as corals, anemones, and giant clams.

The crown-of thorns starfish, Acanthaster planci, has been blamed for coral mortality in a large number of coral reef systems in the Indo-Pacific region. Because population outbreaks of A. planci are closely related to reproduction, it is important to examine the mechanism of reproductive control in this starfish. Previously, a relaxin-like gonad-stimulating peptide (RGP) in starfish Asterina pectinifera has been identified as the gonadotropin responsible for final gamete maturation. On the basis of homology research on RGP cDNAs from several species, this study was carried out to identify gonadotropin in A. planci. The cDNA sequence of RGP was determined using a RACE product of mRNA from the radial nerves of A. planci. The coding DNA sequence consisted of 351 base pairs with an open reading frame encoding a peptide of 116 amino acids (aa), including a signal peptide (29 aa), B-chain (19 aa), C-peptide (44 aa), and A-chain (24 aa). The chemical structure of A. planci RGP was exactly the same as that of A....

Most reef-building corals in tropical and subtropical areas symbiose with microalgae from the genus Symbiodinium (dinoflagellate) and depend on the photosynthate produced by the microalgae. The majority of corals acquire Symbiodinium from the surrounding environment through horizontal transfer, but the molecular mechanisms involved in the acquisition of Symbiodinium remain unknown. It has been hypothesized that carbohydrate-binding proteins, or lectins, of the host coral recognize cell surface carbohydrates of Symbiodinium in the process of acquiring symbionts. Thus, we examined the molecular mechanisms involving lectins and carbohydrates using model organism Acropora tenuis, a common reef-building coral, and Symbiodinium culture strains. Juvenile polyps acquire more cells of Symbiodinium strain NBRC102920 at 72–96 h of metamorphosis induction than in any other period. Glycosidase treatment of Symbiodinium inhibited the acquisition of Symbiodinium by juvenile coral polyps. The presence of carbohydrates D-galactose, N-acetyl-D-galactosamine, and N-acetyl-D-glucosamine at 10 mM also tended to decrease Symbiodinium acquisition. We isolated two N-acetyl-D-galactosamine binding lectins with apparent molecular masses of 14.6 and 29.0 kDa from A. tenuis, and de novo sequencing and cDNA cloning showed that the 29.0 kDa protein is Tachylectin-2-like lectin (AtTL-2). The anti-Tachylectin-2 antibody is suggested to bind specifically to AtTL-2. The antibody also inhibited binding of AtTL-2 to N-acetyl-D-galactosamine-resin and the acquisition of Symbiodinium by juvenile A. tenuis polyps. Based on these results, AtTL-2 is likely involved in the process of Symbiodinium acquisition., 論文

Scleractinian corals host photosynthetic endosymbionts, making direct measurement of the host respiration rate via incubation methods based on O2 consumption impossible. We tested the use of the respiratory electron transport system activity (ETSA) for measuring host potential respiration. The applied method, modified from a previous study, is based on the re - duction of (4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) to formazan. After the development of a protocol suitable for corals, the method was tested on 5 different spe- cies. Metabolism, including photosynthesis, dark respiration and light and dark calcification, was measured through incubation. Host and zooxanthellae fractions were separated and their ETSAs, protein contents and zooxanthellae densities were measured. Mean ETSA/dark respiration (ETSA/R) ratios for host corals ranged from 1.7 ± 0.2 to 3.5 ± 0.6, while ratios for zooxanthellae ranged from 3.7 to 7.8. The high ratios observed for zooxanthellae indicate that their respiration may be 5 times higher under light conditions than in the dark. Considering the obtained ratios, host respiration in light could increase at most by a factor of 3.5 compared with dark respiration rates. Ratios close to 1 were found for some specimens, which suggests that higher respiration rates under light compared with dark conditions are not possible. Therefore, increased respiration in light cannot explain the observed enhancement of calcification under light conditions. ETSA was correlated with zooxanthellae density, suggesting adaptation of the levels of host ETS enzymes to the amount of translocated photosynthetates under optimal conditions. Estimated dark host respiration was correlated with photosynthesis, which suggests that it is determined mainly by the amount of energy available but also the amount of electron transport system enzymes. This constrains the amount of ATP available for calcification. Hence, we propose a mechanism by which respiration limits the calcification rate.

A method for estimating the fatigue life of Pb-free solder (Sn–3.0Ag–0.5Cu) bump joints under thermal cycling is described. The test specimens were 4, 6 and 8 mm chip size packages mounted on printed circuit boards. To develop a semi-analytical model for estimating the thermal fatigue life, thermal cycle tests were carried out on the test specimens and the thermal fatigue life obtained experimentally was compared with the corresponding result from nonlinear, elastic–plastic finite element analysis. It was found that the chip size affected the thermal fatigue life and the strain accumulated in the solder bumps during thermal cycling. This was due to the difference in mechanical boundary conditions around the Si chip. Based on the Coffin–Manson law, an equation for estimating the thermal fatigue life was derived and the predicted fatigue life for various chip sizes and under different rises in temperature were found to be in good agreement with the experimental results. Moreover, a measurable parameter that correlates with the accumulated strain in the solder bumps was introduced for estimating the thermal fatigue life of the test specimens.

The creep properties, that is, the velocity constant, activation energy, stress index, and time index, of a test piece (TP) cut from a glass-fiber-reinforced nylon 6 product were successfully determined by a compression creep test. In the determination of the creep properties, the experimental creep curves for the TP were fitted by finite element analysis (FEA). Fiber-reinforced nylon 6 beams with different fiber orientations were also prepared, and their creep properties were successfully determined by a combination of the bending creep test and the corresponding analysis. The creep behavior of the press-fit component composed of a metal collar and a fiber-reinforced nylon 6 product was predicted by FEA with the determined creep properties of the TP. The predicted retention forces were in good agreement with the experimental ones. The effects of the fiber orientation on the long-term reliability of the press-fit component are also discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

All corals have a common structure: two tissue layers enclose a lumen, which forms the gastric cavity. Few studies have described the processes occurring inside the gastric cavity and its chemical and biological characteristics. Here, we show that the coral gastric cavity has distinct chemical characteristics with respect to dissolved O2, pH, alkalinity, and nutrients (vitamin B12, nitrate, nitrite, ammonium, and phosphate) and also harbors a distinct bacterial community. From these results, the gastric cavity can be described as a semi-closed sub-environment within the coral. Dissolved O2 shows very low constant concentrations in the deepest parts of the cavity, creating a compartmentalized, anoxic environment. The pH is lower in the cavity than in the surrounding water and, like alkalinity, shows day/night variations different from those of the surrounding water. Nutrient concentrations in the cavity are greater than the concentrations found in reef waters, especially for phosphate and vitamin B12. The source of these nutrients may be internal production by symbiotic bacteria and/or the remineralization of organic matter ingested or produced by the corals. The importance of the bacteria inhabiting the gastric cavity is supported by the finding of a high bacterial abundance and a specific bacterial community with affiliation to bacteria found in other corals and in the guts of other organisms. The findings presented here open a new area of research that may help us to understand the processes that maintain coral health.

Reproduction and larval/post-larval development of the one of the smallest known comatulid Dorometra sesokonis were studied on the coral reefs of Sesoko-jima Island, Okinawa, Japan. Breeding individuals were found every month from May 2003 to April 2004 indicating continuous reproduction. Individuals possessed both mature ovaries and testes, and were therefore characterized as simultaneous hermaphrodites. This species was observed to be an external brooder in which the embryos developed on the surface of parental genital pinnules until the doliolaria larval stage, and subsequently released doliolariae settled on substrata within 4 days after hatching. Larvae then metamorphosed into the post-larval cystidean stage, which lasted for more than a month. The reproductive features of this species are unique among crinoids, and, together with juvenile morphological features observed in adults, can be interpreted as adaptations to their cryptic habitat, which is subject to frequent natural disturbances.

A new metamorphosis-enhancing macrodiolide, luminaolide (1), was isolated from the crustose coralline algae (CCA) Hydrolithon reinboldii. Its structure was determined by spectroscopic analysis. A fraction (1.30 mug/mL) eluted with 80% aqueous MeOH by ODS gel column chromatography of the same CCA extract induced larval metamorphosis (25.9 +/- 7.4%) against Leptastrea purpurea, and its metamorphosis-inducing activity was further enhanced to 92.6 +/- 2.9% with the addition of 1 (25.6 ng/mL).

The effects of applied voltage, pulse frequency, flow rate and permittivity of dielectric material on the concentration of O3 and NO2 in a Dielectric Barrier Discharge (DBD) air plasma jet are experimentally investigated for industrial applications. Furthermore, the production and decay processes of chemical species and also time dependent chemical species concentration field in a DBD discharge region are numerically analyzed by integrated chemical reaction model with thermofluid flow field. There is a reasonable agreement of O3 and NO2 concentration with experimental data.

Historically, hermatypic corals are defined as a symbiotic system composed of an animal host, corals belonging to the taxa Cnidarian, and a photosynthetic organism, the dinoflagellate Symbiodinium spp., also known as zooxanthellae. The high gross productivity and stability of coral reefs have been explained by the efficiency of the coral-algal symbiotic system in using the low nutrient concentrations found in the surrounding water and their rapid recycling in the water. Although several studies have reported the presence of bacteria closely associated with corals, the mechanisms of the relationships among them, the host and the zooxanthellae, remain to be shown. In this study, evidence for the importance of coelenteric bacteria in corals as a component of the coral symbiotic complex was shown by using a new approach. Vitamin B12, which is produced only by prokaryotes, was chosen as a chemical tool to clarify the symbiotic relationships among bacteria, coral, and zooxanthellae, which require vitamin B12. High vitamin B12 concentrations (up to 700pmol l-1 compared with max. 20pmol l-1 in the surrounding water) and high bacteria abundances (100 times higher than surrounding water) were found in the coelenteron of live corals using a new sampling method. The results led to the hypothesis that prokaryotes are the drivers of internal processes, such as vitamin B12 production, occurring directly inside the coral, forming a semi-closed system. Furthermore, most maintenance of the symbiotic complex is due to internal processes rather than the supply from outside the coral.

We observed a severe reduction in salinity around Khang Khao Island at the end of the rainy season in September and October, 1995, caused by the most serious freshwater flooding in Thailand in recent 15 years. During low tide, corals around Khang Khao Island were exposed to 23‰ at three meters depth, and 25‰ at five meters. As a result, Pocillopora damicornis and a few species of Acropora showed colony bleaching or partial or complete colony death in the field. On the other hand, Porites spp., the dominant corals of this area, did not show any conspicuous effects. Porites lutea could survive five days of experimental exposure to 17‰, the critical salinity for other corals. The chlorophyll-a concentration of P. lutea that become partially bleached after seven days exposure to 20‰ was higher than in normal control fragments. These phenomena suggest that P. lutea has a compensation mechanism against salinity reduction. Both field observations and experiments suggest that lowered salinity caused by runoff during the rainy season is an important factor besides turbidity in establishing the characteristics of the coral community structure around Khang Khao Island. A detailed study of the process of coral community formation in this area may contribute to an understanding of not only the negative effects of continental great rivers on the establishment of coral reefs around tropical continental shores but also the influence of the heavy rainfall on a coral community in the coral reef region by the global climate change.

External chemical signals used by scleractinian corals to recognize suitable substrata for larval settlement and metamorphosis were identified from crustose coralline red algae (CCA). A fragment of coral rubble with CCA induced larval metamorphosis of the scleractinian coral Pseudosiderastrea tayamai . A natural inducer and compounds that enhanced its effect in larval metamorphosis were isolated from the methanol extracts of coral rubble with CCA. A bromotyrosine derivative, 11-deoxyfistularin-3 (10 − 7 M) isolated from the CCA, induced the metamorphosis of P. tayamai larvae (27.5 ± 24.0%). In the presence of fucoxanthinol (10 − 9 M) and fucoxanthin (10 − 9 M), the percentage of metamorphosis induced by the bromotyrosine derivative was further enhanced to 87.8 ± 13.0 and 88.4 ± 17.8%, respectively. Both carotenoids are also found in the coral rubble with CCA. These results suggest that bromotyrosine derivative and carotenoids have a synergistic effect in the metamorphosis of P. tayamai larvae. The synergistic effect provides a higher selectivity for recruitment than a single-component natural inducer for recognizing suitable substrata for larval metamorphosis. Thus, the effect might offer a survival advantage for benthic marine invertebrates.

To determine the friction coefficient of a press-fit pin in thin plating, both experiments and three-dimensional finite element analysis are carried out. The compliant press-fit pins are assembled into printed circuit boards with two types of plated through holes, one is Cu and Sn plated and the other only Cu plated, and the load-displacement relationships of the pin during assembly are recorded. Based on the load-displacement relationships of the pin obtained experimentally and the nodal reactions of the pin contacting with the plated hole, obtained from numerical analysis, performed assuming a fiction-less condition, the friction coefficients of the pin in plated holes during assembly are successfully determined. The friction coefficient of the pin in the Sn/Cu plated hole exhibits a higher value than that for the Cu plated hole during assembly, due to the adhesion in the contacting region. In an attempt to check the validity of the determined coefficients of friction, different press-fit assemblies are considered, and the load-displacement relationships of the pin are predicted. The simulations are found to be in good agreement with experimental measurements. The retention forces between the pin and the plated holes are also predicted.

Porites cylindrica and Porites lutea fragments of colonies were inflicted with five different injury types: chisel, file, Water Pik, osmotic and cement injuries. The fragments were maintained in outdoor aquaria for a period of 240 days under light intensities varying from 2–5% to 70–90% of incident surface photosynthetic active radiation (PAR 0 ). During the exposure, changes in weight of the fragments, the rates of regeneration of the injuries, abundance of algae and animals settled onto injured areas were monitored. The regeneration rate of the injuries depended on interspecific differences in corals, injury types, number and composition of algae and animals settled onto the lesions, and light and temperature conditions. Competitive interactions between polyps and settlers occurred after colonizers settled onto the damaged surface or the live tissue. It is noteworthy that recovered coral tissue generally overgrew about 100 algal species with or without inhibition of coral growth by algae. In the summer period, the cyanobacterium Lyngbya majuscula covered some lesions (osmotic and cement) by 100%, thus reducing dramatically the regeneration rate of the inflicted injuries and also caused coral bleaching when in direct contact.

A cDNA encoding a major egg protein was cloned in Galaxea fascicularis, a hermatypic coral with a gonochoric breeding system, and gene expression at the transcriptional level was compared between female and functional male colonies. In an electrophoretic analysis, four soluble proteins were present in high abundance in the female egg, but not in the pseudo-eggs of functional males. Partial amino acid sequences of one of the major proteins named GfEP-1 (88 kDa) were determined, and a cDNA fragment of about 2 kb containing a partial GfEP-1 sequence was isolated. The deduced amino acid sequence exhibited sequence similarities to vertebrate and invertebrate vitellogenins. GfEP-1 transcripts were detected in both sexes 0–1 month before spawning. However, the mRNA levels were significantly higher in females than in functional males. The expression of GfEP-1 may be utilized in sexing and also monitoring effects of environmental and anthropogenic factors on vitellogenesis and sex determination.

There are accumulating reports showing that the El Niño/Southern Oscillation (ENSO) has a significant effect on the population dynamics of marine fishes. However, the influence of ENSO on the physiology of fishes, as possible components of those ecological changes in fish populations, is not fully understood. This study investigated the cellular, physiological, and organismal stress responses in a wild fish population under natural thermal stress. The sea surface temperature at the subtropical ocean of Okinawa, Japan, was the highest in the last 10 years (>32°C) during the summer of 1998 with a strong ENSO. To examine the effects of those unusually warm ocean temperatures on fish, we compared tissue 70-kDa heat shock protein (HSP70) levels and growth rates between the ENSO summer of 1998 and the normal summer of 1999 in a common fish species in Okinawa, the Indo-Pacific sergeant, Abudefduf vaigiensis. We also conducted a complementary heat shock experiment in the laboratory. The field collected Indo-Pacific sergeant had significantly higher muscle HSP70 levels in 1998 than 1999. Higher muscle HSP70 and plasma cortisol levels were observed at 32°C than at 28°C in the laboratory heat shock experiment, indicating that the highest summer ocean temperature in 1998 was sufficient for the fish to up-regulate the cellular and physiological stress responses. In support of this effect, otoliths showed slower growth rates of the fish during the summer of 1998; this may reflect the significant energetic cost of these stress responses.

The seasonal dynamics of size-fractionated phytoplankton biomass in a coral reef area were investigated off Sesoko Island, Okinawa, Japan. Chlorophyll (Chl) a and nutrient concentrations were low almost all year round, showing no clear seasonal variability with values similar to those in some other coral reef areas. Picoplankton dominated the phytoplankton community; average contributions of pico-, nano- and microplankton to the total Chl a biomass were 52, 34 and 11%, respectively. However, in 1998, when the seawater ttemperature was extremely high and coral bleaching occurred due to the ENSO event, low Chl a coupled with high nutrient concentrations were observed. This was associated with a decrease in the picoplankton size fraction. We suggest that the high seawater temperature in 1998 decreased the growth rate of the picoplankton; however, the micro- and nanoplankton may also be limited by other factors such as low nutrient concentrations.

We examined the genotypic diversity of the large population of Heliopora coerulea, discovered recently in Ooura Bay, northern Okinawa Main Island Japan, together with another large population in Shiraho Reef, also in southwest Japan, using 9 polymorphic microsatellite markers. From each population, 40 samples were systematically collected along 2 transect lines with 4-m intervals. Surprisingly, all 40 samples from Ooura Bay were mono-genotypic, implying that the huge coral structure (30 m × 80 m) originated from a single larva. Conversely, the 40 samples collected from the Shiraho Reef site all had different genotypes; measurements of genetic diversity, HE and HO, were 0.075–0.975 and 0.064–0.655, respectively. At least four factors are considered to make such a huge H. coerulea population with a single genotype in Ooura Bay, (1) origin of single larva or fragment (2) a genetic bottleneck, (3) post settlement selection, and (4) frequent asexual propagation.

The coral species, Montipora digitata and seagrass, Thalassia hemprichii , co-inhabit the southern portion of the reef moat in Bise, Okinawa, Japan. To elucidate the biogeochemical relationship between coral and seagrass in mixed communities of the coral reef ecosystem, the carbon metabolisms and the inorganic nitrogen flux rates were estimated in various reef habitats. We used benthic chambers to investigate sandy, seagrass, coral-seagrass mixed communities, coral, and acorn worm habitats. Relatively high concentrations of nitrate and nitrite ions (NO x ) were observed in all habitats due to coastal groundwater inflow. The uptake rate constant of NO x was the highest in the coral-seagrass habitat and was significantly different from the rate constant in the seagrass habitat, indicating that seagrass benefits from co-inhabitation with coral. Dissolution of CaCO 3 was observed in the seagrass and coral-seagrass communities. This decline in basal coral carbonate substrate may contribute to increased fragmentation and dispersal of the coral habitat. On a biogeochemical scale, the coral-seagrass relationship benefits the seagrass in terms of NO x availability and benefits the coral in terms of carbonate dissolution, increasing fragmentation, and furthering habitat development.

In the tropical zones of the Indo-Pacific Oceans, the crown-of-thorns sea star Acanthaster planci, as the predator of corals, destroys coral reefs. We recently found that viscera of the sea urchin Toxopneustes pileolus produced a feeding attractant for this sea star. Using our simple bioassay system, we isolated arachidonic acid and α-linolenic acid as feeding attractants from T. pileolus. This is the first report about the sea star A. planci being attracted to unsaturated fatty acids. Interestingly, other unsaturated fatty acids such as eicosapentaenoic acid, docosahexaenoic acid and linoleic acid showed no activity. Our preliminary experiments indicated that these attractants have an attractive effect for the sea star both in the aquarium and in the sea. We anticipated that these attractants could be used to control A. planci. In addition, we verified the existence of arachidonic acid in the coral as one of the feeding attractants.

To clarify the relationship between the regional variability of water temperatures and the spatially non-uniform appearances of coral mass bleaching and consequent mortality, we have investigated the near-shore temperatures continuously monitored around the Ryukyu Islands in 1999 and NOAA–SST image data in 1998 and 1999. They indicate appreciable regional differences in temperature (e.g., at the Kerama Islands located southwest of Okinawa Island the temperature in summer was generally lower than that at the Okinawa Island coasts). Comparison of the solar radiation distribution and NOAA-SST images with bottom bathymetry and a numerical experiment suggest that the presence of the shelf around the Kerama Islands caused the relatively lower temperature (i.e., the warm water mass from the Kuroshio currents may be propagated toward Okinawa Island but may be blocked at the shelf edge, resulting in relatively lower temperature at the Kerama Islands). Further comparison with the reported changes in the coral coverage in the Ryukyu Islands after the mass coral bleaching event in summer 1998 suggests that one of the primary causes of the regional variability of the coral bleaching and consequent mortality is the regional variation of water temperature.

Larger foraminifera living in the upper 50 m in front of the fringing coral reef northwest off Sesoko Island, Japan show strong habitat differences. This study closely examines the distributions of larger foraminifers and relates these to a number of key environmental factors using rigorous statistical methods. Since all larger foraminifera house symbiotic algae, light attenuation by the water column is the most important limiting factor that must be dealt with wall structures. Water energy is also countered by test structure. The local topography is responsible for different intensities of hydrodynamic forces, which are expressed in various substrates, mostly coral rubble and coarse-grained sand. The genus Peneroplis, very common on the reef flat, clearly prefers hardgrounds of the shallowest slope parts down to 30 m, while Dendritina is restricted to sandy bottoms and avoids the uppermost meters of the slope. It can be found down to 50 m at least. Alveolinella shows a similar depth distribution to Dendritina, but is common on hard bottom. The distribution of Parasorites, which is restricted to sandy substrates, starts at 20 m and extends to 80 m. Sorites, on the other hand, was found only on firm substrates between the reef edge and 50 m. The same depth distribution was recorded for Amphisorus, but this genus is not correlated with specific substrates. Most of the Amphistegina species prefer hardgrounds, while Amphistegina radiata is also common on sand. The calcarinids, capable of withstanding high water energy, are abundant on firm substrates close to the reef edge. Only Baculogypsinoides inhabits deeper parts of the slope on sandy bottom and avoids the shallowest parts. Sections with hard substrates are settled by Heterostegina, even down to 80 m, although this genus was occasionally found on sandy bottoms. Nummulites, in contrast, is restricted to sands between 20 and 70 m. Operculina, starting at 20 m, also prefers sandy substrates, but rare individuals were detected on coral rubble and macroids.