Male Pheromones Induce Ovulation in Female Honeycomb Groupers (Epinephelus merra): A Comprehensive Study of Spawning Aggregation Behavior and Ovarian Development

This study characterizes the spawning phenomena of the honeycomb grouper (Epinephelus merra), which is a lunar-synchronized spawner that spawns a few days after full moon. To elucidate the aggregation characteristics of wild honeycomb groupers, the numbers of males and females at the spawning grounds were counted before and after the full moon. Approximately 20 males were consistently observed at the spawning grounds throughout the study period. Females appeared several days after full moon and rapidly increased in number, peaking four days after full moon (41 individuals). The maturation status of the females aggregating at the spawning grounds was investigated. The gonadosomatic index increased rapidly three days after full moon, and ovulation was confirmed. Individuals with ovulatory eggs were present for three days, after which the number of females at the spawning grounds decreased. Additionally, the role of males in final oocyte maturation (FOM) and ovulation in females during the spawning phase was investigated in captivity. FOM was induced in females reared in water with mature males, suggesting that male pheromones in the water induced FOM via activation of the hypothalamic–pituitary–gonadal axis. This suggests that spawning at the natural spawning grounds was the result of male–female interactions via pheromones

Controlling factors of large-scale harmful algal blooms with Karenia selliformis after record-breaking marine heatwaves

Unprecedented, large-scale harmful algal blooms (HABs) dominated by Karenia selliformis occurred off the southeastern coast of Hokkaido, Japan, from late September to early November 2021, about a month after intense and extensive marine heatwaves (MHWs) had subsided. The aims of the present study were to understand the mechanism of development, maintenance, and decay of the HABs as well as to investigate the effect of the MHWs on the HABs. We developed a one-dimensional, lower trophic-level ecosystem model (NEMURO+) to simulate the HABs. The model successfully simulated the 2021 HABs and indicated that their development, maintenance, and decay were controlled primarily by changes of water temperature. Nitrate supply from subsurface layers by seasonal vertical diffusion in autumn also helped to maintain the HABs. Vertical diffusion following MHWs in 2021 contributed to the long duration of the preferred temperature for K. selliformis and the occurrence of pre-bloom of K. selliformis, resulting in preconditioning and accelerating the HABs. However, simulations for normal years (i.e., the climatological mean during 2003–2018) showed that HABs could have occurred, even in the absence of MHWs. The simulations indicated that massive blooms of other phytoplankton species (e.g., diatoms) would not have occurred in 2021, even in the absence of a K. selliformis bloom. The implication was that the HABs in 2021 were the species-specific responses of K. selliformis. The proposed mechanism of the HABs was peculiar to our study area and differed from that previously reported for other K. selliformis blooms. Specifically, the preferred temperature for the HABs of K. selliformis was clearly lower than the previously reported preferred temperature of K. selliformis; thus, the physiological characteristics of the K. selliformis that bloomed in our study area differed from those of other K. selliformis strains. These discoveries provide the first evidence to explain how MHWs affect HABs, and to understand how inter-regional dissimilarities of K. selliformis can lead to large-scale, devastating outbreaks under different oceanographic conditions

The Impact of Tofogliflozin on Physiological and Hormonal Function, Serum Electrolytes, and Cardiac Diastolic Function in Elderly Japanese Patients with Type 2 Diabetes Mellitus

The sodium glucose transporter 2 (SGLT2) inhibitor tofogliflozin is a glucose-lowering drug that causes the excretion of surplus glucose by inhibiting SGLT2. Because of tofogliflozin’s osmotic diuresis mechanism, patients’ serum electrolytes, body fluid levels, and cardiac function must be monitored. We retrospectively analyzed the cases of 64 elderly Japanese patients with type 2 diabetes mellitus (T2DM) who received tofogliflozin for 3 months. Their HbA1c, serum electrolytes (sodium, potassium, chloride), hematocrit, brain natriuretic peptide (cardiac volume load marker) and renin and aldosterone (RAA; an index of regulatory hormones involved in body fluid retention) were continuously monitored during the investigation period. Renal function and cardiac function (by echocardiography) were assessed throughout the period. HbA1c significantly decreased (β1=−0.341, p<0.0001, linear regression analysis [LRA]). Most of the hormonal, electrolyte, and physiological parameters were maintained throughout the study period. In these circumstances, E/e’ tended to decrease (β1=−0.382, p=0.13, LRA). Compared to the baseline, E/e’ was significantly decreased at 1 and 3 months (p<0.01, p<0.05). In the higher E/e’ group (E/e’≥10, n=34), E/e’ decreased significantly (β1=−0.63, p<0.05, LRA). ΔE/e’ was correlated with body-weight change during treatment (r=0.64, p<0.01). The 3-month tofogliflozin treatment improved glycemic control and diastolic function represented by E/e’ in T2DM patients, without affecting serum electrolytes, renal function, or RAA. No negative impacts on the patients were observed. Three-month tofogliflozin treatment lowered glucose and improved cardiac diastolic function

Male Pheromones Induce Ovulation in Female Honeycomb Groupers (Epinephelus merra): A Comprehensive Study of Spawning Aggregation Behavior and Ovarian Development

This study characterizes the spawning phenomena of the honeycomb grouper (Epinephelus merra), which is a lunar-synchronized spawner that spawns a few days after full moon. To elucidate the aggregation characteristics of wild honeycomb groupers, the numbers of males and females at the spawning grounds were counted before and after the full moon. Approximately 20 males were consistently observed at the spawning grounds throughout the study period. Females appeared several days after full moon and rapidly increased in number, peaking four days after full moon (41 individuals). The maturation status of the females aggregating at the spawning grounds was investigated. The gonadosomatic index increased rapidly three days after full moon, and ovulation was confirmed. Individuals with ovulatory eggs were present for three days, after which the number of females at the spawning grounds decreased. Additionally, the role of males in final oocyte maturation (FOM) and ovulation in females during the spawning phase was investigated in captivity. FOM was induced in females reared in water with mature males, suggesting that male pheromones in the water induced FOM via activation of the hypothalamic–pituitary–gonadal axis. This suggests that spawning at the natural spawning grounds was the result of male–female interactions via pheromones

Distribution pattern and habitat use of the protandrous shrimp Pandalus latirostris in relation to environmental characteristics in Akkeshi waters on the pacific coast of eastern Hokkaido, Japan

A sampling of the protandric shrimp, Pandalus latirostris, was conducted at fixed sites from July 2015 to March 2020 in Akkeshi Bay and the connecting Lake Akkeshi on the Pacific coast of eastern Hokkaido. Based on the occurrence pattern of P. latirostris, most individuals begin mating as males at Age-1, followed by a sex change to females, spawn eggs as females at Age-2, and hatch their eggs in the spring of Age-3. Pre-hatching ovigerous females were mainly found in eelgrass beds near and in Lake Akkeshi, where the water temperature was relatively high. The females probably migrate there to hatch their eggs, making sure of the high survival and growth of the hatched larvae. Juveniles and small males were also abundant in near and in Lake Akkeshi, indicating that many larvae remained in the eelgrass beds where they hatched. These eelgrass beds play an important role in the maintenance of the shrimp population as a major egg-hatching site and nursery habitat in Akkeshi waters. With ontogenetic development, the occurrence rate of P. latirostris gradually increased on the offshore side of Akkeshi Bay, with its body size being larger. As P. latirostris grow, they will probably disperse to the offshore side of Akkeshi Bay. However, the density of P. latirostris in the eelgrass bed in the bay near the lake was extremely high, with its strong preference at all ontogenetic stages. This eelgrass bed would help maintain the shrimp population as a “key habitat” for the shrimp. The site-specific environmental characteristics of vegetation beds influence the distribution and abundance of individuals within a population of P. latirostris through their growth and the associated change in habitat preference. In this study, the importance of maintaining the diverse habitats of P. latirostris will be discussed as part of the shrimp stock management measures

Intraoperative transit-time flowmetry in patients undergoing coronary surgery to determine relationships between graft flow and patency and prior coronary interventions and flow demand: a retrospective study

Abstract Background The aim of this study was to delineate impacts of percutaneous coronary intervention (PCI), flow demand, and status of myocardium on graft flow. Methods We retrospectively assessed 736 individual coronary artery bypass grafts that had been created as the sole bypass graft for a vascular region in 405 patients. The grafts comprised 334 internal thoracic artery (ITA) to left anterior descending (LAD), 129 ITA and 65 saphenous vein grafts (SVG) to left circumflex (LCX), and 142 gastroepiploic artery (GEA) and 66 SVG to right coronary artery (RCA). Minimal luminal diameter, size of revascularized area, history of myocardial infarction, and PCI in the relevant area were examined to determine whether these factors are associated with flow insufficiency (FI), which was defined as ≤ 20 mL/min. Results FI developed in 123/736 grafts (16.7%) and correlated significantly with stenosis in the distal portion (23.0% vs. 12.8%, p = 0.0003). Prior myocardial infarction significantly correlated with FI in GEA–RCA (p = 0.002) and ITA–LCX grafts (p = 0.04). There was a history of PCI to the LAD (PCI group) in 54 ITA to LAD bypass grafts (16.2%), whereas the remaining 280 had no history of PCI to the LAD (no-PCI group). Graft flow was significantly greater in the no-PCI than in the PCI group (53 ± 29 vs. 42 ± 27; p = 0.006). The incidences of FI and graft failure were significantly higher in the PCI than the no-PCI group (22.2%, vs. 8.2%; p = 0.003; 9.2% vs. 1.8%; p = 0.003, respectively). Conclusions Prior PCI has a negative impact on graft flow. The influences of small revascularized area, myocardial infarction, and PCI are greater, necessitating consideration of factors associated with flow demand or microvasculature when planning revascularization