Citizen science via social media revealed conditions of symbiosis between a marine gastropod and an epibiotic alga.

Environmental factors promote symbiosis, but its mechanism is not yet well understood. The alga Pseudocladophora conchopheria grows only on the shell of an intertidal gastropod Lunella correensis, and these species have a close symbiotic relationship which the alga reduces heat stress of the gastropod. In collaboration with general public, we investigated how environmental conditions alter the symbiotic interaction between the alga and the gastropod. Information about the habitats of each gastropod and images of shells was obtained from the Japanese and Korean coasts via social media. We constructed the hierarchical Bayesian model using the data. The results indicated that the proportion of shell area covered by P. conchopheria increased as the substrate size utilized by the gastropod increased. Meanwhile, temperature did not affect the proportion of P. conchopheria on the shell. These suggested that the alga provides no benefits for the gastropod on small substrates because gastropod can reduce the heat stress by diving into the small sediment. Further, the gastropod's cost incurred by growing the alga on the shell seems to be low as the algae can grow even in cooler places where no benefits of heat resistance for gastropods. Different environments can yield variable conditions in symbiosis.

Simple-measured leg muscle strength and the prevalence of diabetes among Japanese males: a cross-sectional analysis of data from the Kameda health study.

[Purpose] The aim of this study was to investigate the relationship between leg muscle strength, measured by a very simple one-leg stand-up test, and the prevalence of diabetes among Japanese males to raise awareness of diabetes prevention. [Participants and Methods] This cross-sectional analysis was conducted in 1,800 Japanese males (median [interquartile range] age, 61 [56-67] years) who completed health examinations and a one-leg stand-up test. The prevalence of diabetes was defined if any of the following conditions applied: 1) fasting blood glucose level more than 126 mg/dl, 2) two-hour blood glucose level more than 200 mg/dl (75-g oral glucose tolerance test), 3) HbA1c more than 6.5%, 4) diagnosed with diabetes by a physician, and/or 5) treated for diabetes. [Results] There were 490 participants with diabetes, and 517 participants were unable to complete the sit-to-stand task. When males, who could stand up, were used as a reference, the odds ratio for the prevalence of diabetes was significantly higher among those who were unable to stand up on neither leg than those who successfully stood up on both right and left legs after adjustment for covariates. [Conclusion] Low leg muscle strength, as measured by the one-leg stand-up test, was associated with a higher prevalence of diabetes among Japanese males. Because of its simplicity, this test could be useful detecting individuals who are at increased risk of developing diabetes.

Stand-up test overestimates the decline of locomotor function in taller people: a cross-sectional analysis of data from the Kameda Health Study.

[Purpose] The purpose of this study was to identify which physical attribute could influence each outcome in the Stand-up test and the Two-step test and the degree of their involvement. [Participants and Methods] The participants were 2,476 people (1,674 males and 802 females), who underwent a two-day health checkup and were requested to take the Locomotive Syndrome Risk Test (Locomo Test). Participants were divided into groups under the Locomo level based on the result of Locomo Test by gender. Furthermore, the relationship between each physical attributes (quartile) based on the result of Locomo Test and the Locomo level was evaluated. [Results] According to the relationship between each physical attributes and Locomo level 1 in the Stand-up test, height showed a positive relationship and the multivariable adjusted odds ratio significantly increased with taller height in both genders. Body weight and BMI showed a negative relationship, although rather weak positive relationship, it was identified in waist circumference. On the other hand, there was no clear correlation between each physical attribute and Locomo level 1 in the Two-step test. [Conclusion] The findings indicate The Stand-up test would overestimate the decline of locomotor function in taller people and would underestimate it in shorter individuals.

Analysis of life-history traits in a sex-changing marine shrimp (decapoda: caridea: rhynchocinetidae).

The hypothesis of protandrous (male to female) sex change was tested for the first time in a rhynchocinetid shrimp, Rhynchocinetes uritai, with an analysis of life-history traits. Samples were taken monthly for 2 years in Oura Bay, Japan, using a combination of bait and refuge traps. Breeding was seasonal but extended from spring through autumn, with female-phase individuals (FPs) producing broods successively, with their ovaries maturing for a new spawn during incubation of a previous brood. Females incubated numerous (∼500-4000) embryos that suffered insignificant mortality before hatching. Recruitment of juveniles after planktonic larval development began in summer and peaked during the autumn, with negligible recruitment during winter and spring. Cohort analysis confirmed the hypothesis of protandric sex change in this species, with juveniles maturing into the male phase (MP) during their first reproductive season at an age of 6-10 mon, depending on the time of recruitment. Sex change occurred during the following winter when transitional individuals matured into FPs during their second reproductive season at an age of ≥18 mon. Two cohorts were followed from recruitment until the end of the study, indicating a life span of 21-25 mon. Aside from its sexual system, this sex-changing species showed no obvious differences in reproductive and other life-history traits from those of gonochoric species from similar latitudes and habitats.