University of the Ryukyus University Hospital

Two studies examined the effects of an apology on a victim's aggression and explored the psychological mechanisms underlying such effects. In Study 1, female undergraduates were psychologically harmed and then received an apology by another female student. In Study 2, male undergraduates were asked to role play a victim in a hypothetical harm situation. Results indicate that when the harm-doers apologized, as opposed to when they did not, the victim-subjects refrained from severe aggression against them. Regression analyses suggested that such aggression-inhibitory effects of an apology were mediated by impression improvement, emotional mitigation, and reduction in desire for an apology within the victims. It was also found that when the harm was severe, such effects of an apology on aggression were attenuated. The more severe the harm is, the more extensive of an apology may be needed to alleviate the victim's anger and aggression.

BACKGROUND: Thyroid storm (TS) is life threatening. Its incidence is poorly defined, few series are available, and population-based diagnostic criteria have not been established. We surveyed TS in Japan, defined its characteristics, and formulated diagnostic criteria, FINAL-CRITERIA1 and FINAL-CRITERIA2, for two grades of TS, TS1, and TS2 respectively. METHODS: We first developed diagnostic criteria based on 99 patients in the literature and 7 of our patients (LIT-CRITERIA1 for TS1 and LIT-CRITERIA2 for TS2). Thyrotoxicosis was a prerequisite for TS1 and TS2 as well as for combinations of the central nervous system manifestations, fever, tachycardia, congestive heart failure (CHF), and gastrointestinal (GI)/hepatic disturbances. We then conducted initial and follow-up surveys from 2004 through 2008, targeting all hospitals in Japan, with an eight-layered random extraction selection process to obtain and verify information on patients who met LIT-CRITERIA1 and LIT-CRITERIA2. RESULTS: We identified 282 patients with TS1 and 74 patients with TS2. Based on these data and information from the Ministry of Health, Labor, and Welfare of Japan, we estimated the incidence of TS in hospitalized patients in Japan to be 0.20 per 100,000 per year. Serum-free thyroxine and free triiodothyroine concentrations were similar among patients with TS in the literature, Japanese patients with TS1 or TS2, and a group of patients with thyrotoxicosis without TS (Tox-NoTS). The mortality rate was 11.0% in TS1, 9.5% in TS2, and 0% in Tox-NoTS patients. Multiple organ failure was the most common cause of death in TS1 and TS2, followed by CHF, respiratory failure, arrhythmia, disseminated intravascular coagulation, GI perforation, hypoxic brain syndrome, and sepsis. Glasgow Coma Scale results and blood urea nitrogen (BUN) were associated with irreversible damages in 22 survivors. The only change in our final diagnostic criteria for TS as compared with our initial criteria related to serum bilirubin concentration >3 mg/dL. CONCLUSIONS: TS is still a life-threatening disorder with more than 10% mortality in Japan. We present newly formulated diagnostic criteria for TS and clarify its clinical features, prognosis, and incidence based on nationwide surveys in Japan. This information will help diagnose TS and in understanding the factors contributing to mortality and irreversible complications.

A high level of serum creatinine (S-Cr) is a predictor of end-stage renal disease (ESRD), but only a few studies have investigated the prevalence of high S-Cr and its correlates in a large population. We analyzed the data collected from 6,403 subjects (4,222 men and 2,181 women) who participated in the Okinawa General Health Maintenance Association (OGHMA) screening both at 1997 and 1999. The computer-saved data included sex, age, blood chemistries, blood pressure, medical histories, and lifestyles. Multivariate Cox proportional hazard analyses were performed to identify the correlates of developing high S-Cr levels: > or = 1.4 mg/dl in men and > or = 1.2 mg/dl in women. The prevalence of high S-Cr was 3.0% (N=193), which was 4.1% in men (N=175) and 0.8% in women (N=18), and increased with age in both sexes at the 1997 screening. Among those who showed normal levels of S-Cr in 1997 (N=6,210), 241 subjects (223 men and 18 women) developed high S-Cr. The 2-year cumulative incidence of high S-Cr was 5.5% in men and 0.8% in women. Other than sex, serum uric acid was the most significant correlate for developing high S-Cr. The adjusted relative risk (95% confidence interval) of those with serum uric acid 8.0 mg/dl and over was 2.91 (1.79-4.75) in men and 10.39 (1.91-56.62) in women when compared to those with serum uric acid less than 5.0 mg/dl. Prevalence of high levels of S-Cr was relatively high in men. Other than gender, serum uric acid was a significant positive correlate of developing high S-Cr in this sample of the Japanese population.

The diversity and community structures of symbiotic dinoflagellates are described from reef invertebrates in southern and central provinces of the Great Barrier Reef (GBR), Australia, and Zamami Island, Okinawa, Japan. The symbiont assemblages from region to region were dominated by Clade C Symbiodinium spp. and consisted of numerous host-specific and/or rare types (specialists), and several types common to many hosts (generalists). Prevalence in the host community among certain host -generalist symbionts differed between inshore and offshore environments, across latitudinal (central versus southern GBR) gradients, and over wide geographic ranges (GBR versus Okinawa). One particular symbiont (C3h) from the GBR had a dramatic shift in dominance. Its prevalence ranged from being extremely rare, or absent on high-latitude reefs to dominating the scleractinian diversity on a mid-latitude inshore reef. These changes occurred among coral fauna whose larvae must acquire symbionts from environmental sources (horizontal symbiont acquisition). Such differences did not occur among 'vertical transmitters' such as Porites spp., Montipora spp. and pocilloporids (corals that directly transmit symbionts to their offspring) or among those hosts displaying 'horizontal acquisition', but that associate with specific symbionts. Most host-specialized types were found to be characteristic of a particular geographic region (i.e. Okinawa versus Central GBR versus Southern GBR). The mode of symbiont acquisition may play an important role in how symbiont composition may shift in west Pacific host communities in response to climate change. There is no indication that recent episodes of mass bleaching have provoked changes in hostsymbiont combinations from the central GBR.

BACKGROUND: The prognosis of chronic dialysis patients is poor, in part due to the high incidence of cardiovascular disease. Malnutrition, such as hypoalbuminaemia, has been shown to be a predictor of death in this group of patients, while serum C-reactive protein (CRP) is a predictor of myocardial infarction and sudden death. Thus, the aim of the present study was to determine of the relationship between CRP and serum albumin concentration, and the value of baseline CRP data in the prediction of death. METHODS: In one of the dialysis units in Okinawa, Japan, baseline CRP data was available (n=163, 95 men and 68 women) in January 1991. These patients were divided into two groups according to their baseline CRP levels, with group 1 consisting of CRP<10 mg/l (n=128) and group 2 of CRP> or =10 mg/l (n=35), and then followed up until the end of 1997. Survival curves were calculated using the Kaplan-Meier method. The statistical significance of the relationship between CRP levels and the risk of death was evaluated by multiple logistic analysis with covariables such as age, sex, diabetes mellitus, serum albumin, and blood pressure. RESULTS: The mean (SD) level of serum albumin was 38 (3) g/l in group 1 and 36 (3) g/l in group 2 (P<0.00001). The 5-year survival rate was significantly poorer in group 2 (44.4%) than in group 1 (82.5%) (P<0.0001). Furthermore, the risk of death was significantly higher in group 2 (relative risk 3.48 (95% confidence interval 1.76-6.89), P<0.0003) by multivariate Cox proportional hazard analysis. CONCLUSIONS: CRP is a significant predictor of death in chronic dialysis patients, independent of serum albumin and other possible confounders. Dialysis patients with high CRP levels should be carefully evaluated and monitored regardless of serum albumin concentrations in the normal range.

OBJECTIVE: To identify the 140-kd autoantigen recognized by anti-155/140 autoantibodies that are associated with adult cancer-associated dermatomyositis (DM) and juvenile DM and to determine the clinical relevance of anti-155/140 antibodies in a large cohort. METHODS: Sera from 456 DM patients were assessed for the presence of anti-155/140 antibodies by immunoprecipitation using K562 cell extracts as substrate. Using immunoprecipitation and Western blotting, we then examined whether anti-155/140-positive sera recognized transcription intermediary factor 1α (TIF-1α), TIF-1β, and TIF-1γ. The clinical associations of antigen reactivity were also evaluated. RESULTS: Anti-155/140-positive sera reacted with 140-kd TIF-1α in addition to 155-kd TIF-1γ. Among sera from 456 DM patients, 52 were reactive with both TIF-1α and TIF-1γ, while another 25 were reactive with TIF-1γ alone. Additionally, 7 were reactive with TIF-1β. Malignancy was more frequently found in adult patients with both anti-TIF-1α and anti-TIF-1γ antibodies than in those with anti-TIF-1γ antibodies alone (73% versus 50%; P < 0.05). In addition to juvenile DM patients and middle-aged and older DM patients with high percentages of malignancy, 8 "young adult" DM patients without malignancy had these autoantibodies. CONCLUSION: Anti-155/140 antibodies target TIF-1 family proteins, TIF-1α and TIF-1β, in addition to TIF-1γ. Since TIF-1 proteins have significant roles in oncogenesis, these antibodies may be produced during misdirected antitumor immunity.

Among vertebrates, fishes show an exceptional range of reproductive strategies regarding the expression of their sexuality. Fish sexualities were categorized into gonochorism, synchronous/sequential hermaphrodite, or unisexual reproduction. In gonochoristic fishes, sex is determined genetically or by environmental factors. After sex determination, the gonads are differentiated into ovary or testis, with the sex remaining fixed for the entire life cycle. In contrast, some sequential hermaphrodite fishes can change their sex from male to female (protandrous), female to male (protogynous), or serially (bi-directional sex change) in their life cycle. In many cases, sex change is cued by social factors such as the disappearance of a male or female from a group. This unique diversity in fishes provides an ideal animal model to investigate sex determination and differentiation in vertebrates. This review first discusses genetic-orientated sex determination mechanisms. Then, we address the gonadal sex differentiation process in a gonochoristic fish, using an example of the Nile tilapia. Finally, we discuss various types of sex change that occur in hermaphrodite fishes.

Recent submarine, geological, and geophysical investigations including diving surveys reveal the geo-history of the Ryukyu Islands and the East China Sea. Two stages are fundamental for formation processes of the Ryukyu Arc. The crustal thinning in the western part of the East China Sea and thus eastward drifting of the Arc may have occurred in the late Miocene to middle Pliocene at the first stage. Between 1.6 - 1.3 Ma, the East China Sea area, including most of the Okinawa Trough, may have been subaerial. At that time, the Ryukyu Arc region may have been a part of the Eurasian continent. Extensive subsidence may have occurred at the second stage, at about 1.3 Ma, in the early Pleistocene. The present Ryukyu Arc (Ryukyu Ridge) has been formed since then. The Ryukyu Arc may have been nearly connected to the Chinese continent, through Taiwan as a land bridge, sometime during the two major development periods (such as sometime during 1.6 - 1.0 Ma, and 0.2 - 0.025 Ma). The paleo-land may have been submerged step by step since 0.03 Ma by both crustal movement and sea-level rising after the last Ice Age. Submarine stalactite caves at 10 - 35 m deep off the Ryukyu Islands were discovered. The caves have subsided since the Wiirm Ice Age. Stone tools were also recovered inside one of them. Additionally, archeological evidence in the form of a stepped pyramid, estimated at greater than 6,000 years old, has been discovered beneath the sea off Yonaguni Island. Existence of such submarine ruins provide indicators of subsidence processes of the Ryukyu Arc.

OBJECTIVE: To test an intervention to enhance collaborative communication among nurse and physician leaders (eg, nurse manager, medical director, clinical nurse specialist) in two diverse intensive care units (ICUs). BACKGROUND: Collaborative communication is associated with positive patient, nurse, and physician outcomes. However, to date, intervention-focused research that seeks to improve collaborative communication is lacking. METHODS: A pretest-posttest repeated measures design incorporated baseline data collection, implementation of the intervention over 8 months, and immediate and 6-months-post data collection. FINDINGS: Communication skills of ICU nurse and physician leaders improved significantly. Leaders also reported increased satisfaction with their own communication and leadership skills. In addition, staff nurse and physician perceptions of nursing leadership and problem solving between groups increased. Staff nurses reported lower personal stress (eg, more respect from co-workers, physicians, and managers), even though they perceived significantly more situational stress (eg, less staffing and time). CONCLUSION: Study findings provide evidence that nurse-physician collaborative communication can be improved.

Photovoltaic (PV) generators exhibit nonlinear v-i characteristics and maximum power (MP) points that vary with solar insulation. An intermediate converter can therefore increase efficiency by matching the PV system to the load and by operating the solar cell arrays (SCAs) at their maximum power point. An MP point tracking algorithm is developed using only SCA voltage information thus leading to current sensorless tracking control. The inadequacy of a boost converter for array voltage based MP point control is experimentally verified and an improved converter system is proposed. The proposed converter system results in low ripple content, which improves the array performance and hence a lower value of capacitance is sufficient on the solar array side. Simplified mathematical expressions for a PV source are derived. A signal flow graph is employed for modeling the converter system. Current sensorless peak power tracking effectiveness is demonstrated through simulation results. Experimental results are presented to validate the proposed method.

The polysaccharides, such as κ-carrageenan, ι-carrageenan, agarose (agar), gellan gum, amylose, curdlan, alginate, and deacetylated rhamsan gum, in water changed into an ice-like structure with hydrogen bonding between polymer and water molecules, and between water-water molecules even at a concentration range of 0.1% - 1.0% (W/V) at room temperature, resulting in gelation. Such dramatic changes from liquid into gels have been understood at the molecular level in principles. In this review, we describe the structure-function relationship of starch on the view point of rheological aspects and discuss gelatinization and retrogradation mechanism including water molecules at molecular level. The starch molecules (amylose and amylopectin) play a dominant role in the center of the tetrahedral cavities occupied by water molecules, and the arrangement is partially similar to a tetrahedral structure in a gelatinization process. The arrangement should lead to a cooperative effect stabilizing extended regions of ice-like water with hydrogen bonding on the surface of the polymer molecules, where hemiacetal oxygen and hydroxyl groups might participate in hydrogen bonding with water molecules. Thus, a more extended ice-like hydrogen bonding within water molecules might be achieved in a retrogradation process. Though many investigations not only include starch gelatinization and retrogradaion, but also the gelling properties of the polysaccharides have been undertaken to elucidate the structure-function relationship, no other researchers have established mechanism at the molecular level. There is reasonable consistency in our investigations.

There is enormous global anticipation for stem cell-based therapies that are safe and effective. Numerous pre-clinical studies present encouraging results on the therapeutic potential of different cell types including tissue derived stem cells. Emerging evidences in different fields of research suggest several cell types are safe, whereas their therapeutic application and effectiveness remain challenged. Multiple factors that influence treatment outcomes are proposed including immunocompatibility and potency, owing to variations in tissue origin, ex-vivo methodologies for preparation and handling of the cells. This communication gives an overview of literature data on the different types of cells that are potentially promising for regenerative therapy. As a case in point, the recent trends in research and development of the mesenchymal stem cells (MSCs) for cell therapy are considered in detail. MSCs can be isolated from a variety of tissues and organs in the human body including bone marrow, adipose, synovium, and perinatal tissues. However, MSC products from the different tissue sources exhibit unique or varied levels of regenerative abilities. The review finally focuses on adipose tissue-derived MSCs (ASCs), with the unique properties such as easier accessibility and abundance, excellent proliferation and differentiation capacities, low immunogenicity, immunomodulatory and many other trophic properties. The suitability and application of the ASCs, and strategies to improve the innate regenerative capacities of stem cells in general are highlighted among others.

The relation between serum uric acid level and cardiovascular risk factors is complex and has been investigated mainly in men. We examined the correlation between serum uric acid level and obesity, hypertension, dyslipidemia, and diabetes mellitus (DM) in both men and women of a screened cohort in Okinawa, Japan. A total of 9,914 individuals (6,163 men and 3,751 women ranging in age from 18 to 89 years) who were screened at Okinawa General Health Maintenance Association were subjects in this study. Hyperuricemia was defined as a serum uric acid level > or = 7.0 mg/dl in men and > or = 6.0 mg/dl in women. The odds ratios (95% confidence intervals) for the presence of hyperuricemia in men were 1.75 (1.56-1.97) for obesity, 1.42 (1.25-1.62) for hypertension, 1.16 (1.02-1.30) for hypercholesterolemia, 1.80 (1.60-2.03) for hypertriglyceridemia, 1.19 (1.02-1.40) for hypo-high density lipoprotein (HDL) cholesterolemia, and 0.61 (0.49-0.75) for DM; in women, they were 2.02 (1.62-2.53) for obesity, 1.64 (1.29-2.10) for hypertension, 1.31 (1.04-1.65) for hypercholesterolemia, 1.95 (1.51-2.51) for hypertriglyceridemia, 1.53 (0.96-2.44) for hypo-HDL cholesterolemia, and 1.20 (0.76-1.90) for DM. Hyperuricemic subjects had higher rates of coexistence of two or more of these cardiovascular risk factors than non-hyperuricemic subjects (63.8% vs. 43.2% in men; 58.9% vs. 27.6% in women). The present study revealed that hyperuricemia is positively associated with obesity, hypertension, and dyslipidemia in both men and women, and that hyperuricemic subjects tend to have a clustering of these cardiovascular risk factors.

Larval settlement rates, genetic structure, and gene flow of broadcast-spawning (Acropora tenuis) and planula-brooding (Stylophora pistillata) corals (Scleractinia) were compared within a 500 km range in the Ryukyu Archipelago. We conducted a laboratory experiment to investigate planula settlement rates, and a broad sampling survey to determine genetic variation in both species in the Archipelago. In the laboratory experiment, the planulae of S. pistillata settled a few hours after release, while those of A. tenuis started to settle at least 4 d after the release of gametes. The survival rates and competency periods of larvae were higher and longer for A. tenuis than for S. pistillata. These results suggest that broader dispersal is more likely for A. tenuis than for S. pistillata. In the population genetic analysis, we measured local (2 stations in a region) and regional (Okinawa, Kerama and Yaeyama) patterns of genetic variation with allozyme electrophoresis. We also inferred the levels of gene flow in the 2 species. In the study area, gene flow (N e m) and genetic distance (D) were, respectively, higher and smaller for the spawner A. tenuis (N e m = 3.5 to 16.4, D = 0.028 to 0.187) than for the brooder S. pistillata (N e m = 0.9 to 1.5, D = 0.026 to 0.309). Therefore, the planulae settlement rates were well in agreement with gene flow. In addition, for both species, N e m between the Okinawa and Kerama regions (30 to 150 km apart; N e m = 9.4 to 22.5 in A. tenuis and 1.4 to 3.3 in S. pistillata) was higher than that between the Okinawa-Kerama and Yaeyama regions (up to 500 km apart; N e m = 3.1 to 9.4 in A. tenuis and 0.5 to 1.4 in S. pistillata). The results suggest that coral populations in the Kerama Island are a major source of the coral planulae needed for the recovery of both brooding and spawning coral communities around the Okinawa Islands, after the mass-bleaching event in 1998.

Several epidemiological studies have shown a positive association between serum uric acid levels and the risk of hypertension. However, subjects in these studies were mostly men, or were incompletely examined for lifestyle-related variables. We prospectively examined the relation between hyperuricemia and the risk of developing hypertension with consideration for alcohol consumption and smoking habits in a large screened cohort of men and women. A total of 4,489 individuals (2,927 men and 1,562 women) who did not have hypertension and were not currently using antihypertensive medication were examined at the Okinawa General Health Maintenance Association in 1977. Subjects were re-examined in 2000. Hyperuricemia was defined as a serum uric acid level >or=7.0 mg/dl in men and >or=6.0 mg/dl in women. Hypertension was defined as systolic blood pressure (SBP) >or=140 mmHg, and/or diastolic blood pressure (DBP) >or=90 mmHg. A total of 289 subjects (201 men and 88 women) were hypertensive (SBP >or=140 mmHg, and/or DBP >or=90 mmHg) in 2000. Multivariate analysis was performed for development of hypertension in hyperuricemic subjects, adjusted for age, family history of hypertension, alcohol consumption, cigarette smoking, obesity, hypercholesterolemia, hypertriglyceridemia, low high-density lipoprotein cholesterol, and diabetes mellitus. The adjusted odds ratio (95% confidence interval) in men was 1.48 (1.08-2.02) and in women was 1.90 (1.03-3.51) (p <0.05, respectively). The results showed hyperuricemia to be a new predictor of hypertension development in both men and women.

This paper describes the antitumoral activity of branched-chain fatty acid (BCFA) in human breast cancer cells with an emphasis on its effect on fatty acid biosynthesis. First, the relationship between chain-length and antitumoral activity was studied. The highest activity was observed with iso-16:0, and the activity decreased with increase or decrease of the chain-lengths from C16:0. Anteiso-BCFA, as well as iso-series, was cytotoxic to the breast cancer cells. Cytotoxicity of BCFA was comparable to that of conjugated linoleic acid known as antitumoral fatty acid. Incubation of breast cancer cells with BCFA (13-methyltetradecanoic acid) significantly reduced the [14C] acetate incorporation into free fatty acid and fatty acid esters, showing the inhibition of fatty acid biosynthesis by BCFA. Examination of substrate level effect found that BCFA slightly inhibited fatty acid synthetase and acetyl-CoA carboxylase, and significantly the glucose-6-phosphate dehydrogenase which was the main NADPH generating system in breast cancer cells. The present study thus suggests that BCFA synthetically lowers the fatty acid biosynthesis by reducing the precursors, in addition to its direct inhibitory effect on fatty acid synthetase.

Sexual propagation of corals specifically for reef rehabilitation remains largely experimental. In this study, we refined low technology culture and transplantation approaches and assessed the role of colony size and age, at time of transfer from nursery to reef, on subsequent survival. Larvae from Acropora millepora were reared from gametes and settled on engineered substrates, called coral plug-ins, that were designed to simplify transplantation to areas of degraded reef. Plug-ins, with laboratory spawned and settled coral recruits attached, were maintained in nurseries until they were at least 7 months old before being transplanted to replicate coral limestone outcrops within a marine protected area until they were 31 months old. Survival rates of transplanted corals that remained at the protected in situ nursery the longest were 3.9-5.6 times higher than corals transplanted to the reef earlier, demonstrating that an intermediate ocean nursery stage is critical in the sexual propagation of corals for reef rehabilitation. 3 years post-settlement, colonies were reproductively mature, making this one of few published studies to date to rear a broadcasting scleractinian from eggs to spawning adults. While our data show that it is technically feasible to transplant sexually propagated corals and rear them until maturity, producing a single 2.5year-old coral on the reef cost at least US$60. 'What if' scenarios indicate that the cost per transplantable coral could be reduced by almost 80 %, nevertheless, it is likely that the high cost per coral using sexual propagation methods would constrain delivery of new corals to relatively small scales in many countries with coral reefs.

Geochemical characteristics of hydrothermal fluids in the Iheya North hydrothermal field, mid-Okinawa Trough, was investigated. Twelve-years observation reveals temporal variation of vent fluid chemistry potentially controlled by temporally varying pattern of the phase-separation and -segregation, while the constant Element/Cl ratios among the periods and chimneys indicate the stable chemical composition of the source hydrothermal fluid prior to undergoing phase-separation. The high K contents in the estimated source fluid are typical in the arc-backarc hydrothermal systems due to the hydrothermal reaction with the K-enriched felsic rocks. The high I, B and NH4 contents and alkalinity are derived from decomposition of the sedimentary organic matters. Compositional and isotopic properties of gas species, CH4, H2, CO2, and C2H6, strongly suggest a dominance of biogenic CH4 associated with the sedimentary organic matter. Based on the carbon mass balance calculation and the multidisciplinary investigations of the Iheya North hydrothermal system since the discovery, we hypothesized that the microbial methanogenesis occurs not only within the Central Valley where hydrothermal vents exist, but also in the spatially abundant and widespread basin-filling sediments surrounding the Iheya North Knoll, and that the microbially produced CH4 is recharged together with the source fluid into the deep hydrothermal reaction zone. This “Microbial Methanogenesis at Recharge area in hydrothermal circulation” (MMR) model would be an implication for the generation and incorporation of hydrothermal fluid CH4 in the deep-sea hydrothermal systems but also for those of cold seep CH4 and for the presently uncertain hydrothermal fluid paths in the subseafloor environments. In the near future, the IODP drilling will be conducted in the Iheya North hydrothermal system, and give an excellent opportunity to testify our MMR model.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 346:89-96 (2007) - DOI: https://doi.org/10.3354/meps07114 Temporal changes in settlement, lipid content and lipid composition of larvae of the spawning hermatypic coral Acropora tenuis Saki Harii1,4,*, Kazuo Nadaoka1, Masanobu Yamamoto2, Kenji Iwao3 1Department of Mechanical and Environmental Informatics, Graduate School of Information Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan 2Faculty of Environmental Earth Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku, Sapporo 060-0810, Japan 3Akajima Marine Science Laboratory, 179 Aka, Zamami son, Okinawa 901-3311, Japan 4Present address: Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan *Email: h081771@sci.u-ryukyu.ac.jp ABSTRACT: Stored lipids in marine planktonic larvae play an important role in buoyancy and as an energy source and thus are a key to understanding the dispersal and settlement potential of larvae. However, little is known about lipid content and composition in different coral species or their temporal changes during larval dispersal. We examined the lipid content and composition of eggs and planula larvae of Acropora tenuis, a reef-building coral, and their temporal changes over the course of larval dispersal and settlement. The total content and composition of lipids in newly released planulae of the brooding corals A. brueggemanni, Pocillopora damicornis and Heliopora coerulea were also examined for comparison. A. tenuis eggs were positively buoyant; lipids accounted for 85% of their dry weight, but decreased to 50% of their dry weight within 30 d after spawning. Wax esters were a major component of lipids in the eggs; they decreased appreciably by 5 d after spawning and decreased thereafter. In contrast, the phospholipid content remained almost constant. The period of rapid decrease in wax esters occurred before settlement, suggesting that A. tenuis planulae consume mainly wax ester lipids as an energy source during the planktonic phase. In contrast, the lipid content of H. coerulea planulae, which have a shorter dispersal period, was lower (41% of dry weight) than that found in 5-d-old planulae of A. tenuis and newly released planulae of A. brueggemanni and P. damicornis (>58% of dry weight). Triacylglycerols in lipids were detected in P. damicornis and H. coerulea planulae, which settle quickly after release, but not in A. tenuis or A. brueggemanni, suggesting that triacylglycerols are used for rapid energy. These findings suggest that lipids are used for buoyancy and as an energy source and are related to differences in the dispersal period of planulae among coral species. KEY WORDS: Corals · Dispersal · Larvae · Lipid composition · Lipid content · Settlement Full text in pdf format PreviousNextCite this article as: Harii S, Nadaoka K, Yamamoto M, Iwao K (2007) Temporal changes in settlement, lipid content and lipid composition of larvae of the spawning hermatypic coral Acropora tenuis. Mar Ecol Prog Ser 346:89-96. https://doi.org/10.3354/meps07114 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 346. Online publication date: September 27, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.

Ocean acidification is now recognized as a threat to marine ecosystems; however, the effect of ocean acidification on fertilization in marine organisms is still largely unknown. In this study, we focused on sperm flagellar motility in broadcast spawning reef invertebrates (a coral and a sea cucumber). Below pH 7.7, the pH predicted to occur within the next 100 years, sperm flagellar motility was seriously impaired in these organisms. Considering that sperm flagellar motility is indispensable for transporting the paternal haploid genome for fertilization, fertilization taking place in seawater may decline in the not too distant future. Urgent surveys are necessary for a better understanding of the physiological consequences of ocean acidification on sperm flagellar motility in a wide range of marine invertebrates.