Testing multiple hypotheses on the colour change of treefrogs in response to various external conditions.

Amphibians are famous for their ability to change colours. And a considerable number of studies have investigated the internal and external factors that affect the expression of this phenotypic plasticity. Evidence to date suggests that thermoregulation and camouflage are the main pressures that influence frogs' adaptive colour change responses. However, certain gaps in our knowledge of this phenomenon remain, namely: (i) how do frogs adjust their colour in response to continuously changing external conditions?; (ii) what is the direction of change when two different functions of colour (camouflage and thermoregulation) are in conflict?; (iii) does reflectance in the near-infrared region show thermally adaptive change?; and (iv) is the colour change ability of each frog an individual trait (i.e., consistent within an individual over time)? Using Dryophytes japonicus (Hylidae, Hyla), we performed a series of experiments to answer the above questions. We first showed that frogs' responses to continuously-changing external conditions (i.e., background colour and temperature) were not linear and limited to the range they experience under natural conditions. Second, when a functional conflict existed, camouflage constrained the adaptive response for thermoregulation and vice versa. Third, though both temperature and background colour induced a change in near-infrared reflectance, this change was largely explained by the high correlation between colour (reflectance in the visible spectrum) and near-infrared reflectance. Fourth, within-individual variation in colour change capacity (i.e., the degree of colour change an individual can display) was lower than inter-individual variation, suggesting individuality of colour change capacity; however, we also found that colour change capacity could change gradually with time within individuals. Our results collectively reveal several new aspects of how evolution shapes the colour change process and highlight how variation in external conditions restricts the extent of colour change in treefrogs.

Comparative and experimental studies on the relationship between body size and countershading in caterpillars.

Countershading is a gradient of colouration in which the illuminated dorsal surfaces are darker than the unilluminated ventral surface. It is widespread in the animal kingdom and endows the body with a more uniform colour to decrease the chance of detection by predators. Although recent empirical studies support the theory of survival advantage conferred by countershading, this camouflage strategy has evolved only in some of the cryptic animals, and our understanding of the factors that affect the evolution of countershading is limited. This study examined the association between body size and countershading using lepidopteran larvae (caterpillars) as a model system. Specifically, we predicted that countershading may have selectively evolved in large-sized species among cryptic caterpillars if (1) large size constrains camouflage which facilitates the evolution of a trait reinforcing their crypsis and (2) the survival advantage of countershading is size-dependent. Phylogenetic analyses of four different lepidopteran families (Saturniidae, Sphingidae, Erebidae, and Geometridae) suggest equivocal results: countershading was more likely to be found in larger species in Saturniidae but not in the other families. The field predation experiment assuming avian predators did not support size-dependent predation in countershaded prey. Collectively, we found only weak evidence that body size is associated with countershading in caterpillars. Our results suggest that body size is not a universal factor that has shaped the interspecific variation in countershading observed in caterpillars.

Association between urinary iodine concentration and the risk of papillary thyroid cancer by sex and age: a case-control study.

Previous studies on dietary iodine intake and the risk of papillary thyroid cancer (PTC) have demonstrated inconsistent results. We aimed to evaluate the association between urinary iodine concentration (UIC), a surrogate biomarker for dietary iodine intake, and the risk of thyroid cancer stratified by sex and age in an iodine-sufficient area. A hospital-based case-control study was conducted in Seoul, South Korea. A total of 492 cases of newly diagnosed PTC and 595 controls were included. Compared with the lowest quartile of creatine-adjusted UIC (< 159.3 µg/gCr), the highest quartile (≥ 1037.3 µg/gCr) showed an increased risk of PTC (odds ratio [OR] 1.49, 95% confidence interval [CI] 1.04-2.13), especially in those who were < 45 years old (ptrend = 0.01) compared with those who were ≥ 45 years old (ptrend = 0.48). For those who were < 45 years old, a positive association between creatinine-adjusted UIC and the risk of PTC was observed in both men (q4 vs. q1, OR 4.27, 95% CI 1.14-18.08) and women (OR 1.97, 95% CI 1.04-3.78). For those who were ≥ 45 years old, no association was found in any sex. Creatinine-adjusted UIC was positively associated with the risk of PTC, especially in those who were younger than 45 years for both men and women.

Associations of fasting glucose and glycated hemoglobin with vitamin D levels according to diabetes mellitus status in Korean adults.

OBJECTIVES: According to previous studies, vitamin D deficiency might increase the risk of type 2 diabetes mellitus (DM). However, few studies have examined whether vitamin D continues to affect glucose control after DM diagnosis. Therefore, we examined the association between vitamin D and glucose levels in individuals with and without DM. METHODS: We analyzed data for 32,943 adults aged 19 years and older from the 2008 to 2014 Korea National Health and Nutrition Examination Survey. Patients were classified into 3 groups according to the 25-hydroxyvitamin D concentration. DM was defined as a fasting glucose level ≥126 mg/dL, current use of DM medications or insulin injections, or a self-reported diagnosis of DM by a doctor. RESULTS: In male DM patients, the hemoglobin A1c (HbA1c) level increased significantly as vitamin D levels became severely deficient. In male and postmenopausal female with abnormal HbA1c, those with severe vitamin D deficiency had significantly higher HbA1c levels (p for trend=0.004 and 0.022 for male and postmenopausal female, respectively). Significant differences were found between participants with normal and abnormal HbA1c levels in both male and female. However, regardless of sex or menopausal status, there was no significant association between vitamin D and fasting glucose in any of the fasting glucose subgroups. CONCLUSIONS: Male and female with abnormal HbA1c levels showed markedly elevated blood glucose when they also had vitamin D deficiency. A more distinct difference was observed in the HbA1c subgroups than in the fasting glucose subgroups.

Prey with hidden colour defences benefit from their similarity to aposematic signals.

Some camouflaged animals hide colour signals and display them only transiently. These hidden colour signals are often conspicuous and are used as a secondary defence to warn or startle predators (deimatic displays) and/or to confuse them (flash displays). The hidden signals used in these displays frequently resemble typical aposematic signals, so it is possible that prey with hidden signals have evolved to employ colour patterns of a form that predators have previously learned to associate with unprofitability. Here, we tested this hypothesis by conducting two experiments that examined the effect of predator avoidance learning on the efficacy of deimatic and flash displays. We found that the survival benefits of both deimatic and flash displays were substantially higher against predators that had previously learned to associate the hidden colours with unprofitability than against naive predators. These findings help explain the phenological patterns we found in 1568 macro-lepidopteran species on three continents: species with hidden signals tend to occur later in the season than species without hidden signals.

Diabetes and COVID-19: IDF perspective in the Western Pacific region.

The World Health Organization (WHO) declared a pandemic, the highest risk level in the infectious disease alert phase, on 11 March 2020. In the Western Pacific Region (WPR), 192,016 confirmed cases with 7125 deaths had been reported as of 8 June 2020. In people with diabetes COVID-19 can be more difficult to treat due to the wide fluctuations in blood glucose levels or presence of comorbidities such as diabetes complications, including cardiovascular disease and renal damage, which are recognized risks for adverse outcomes. National diabetes associations and governments have established guidelines for subjects with diabetes in relation to COVID-19, and are trying to supply emergency and their regularly required medical products for them. The WPR is so large and composed of such diverse countries and COVID-19 situations, no one conclusion or program applies. Instead we could see a diverse COVID-19 pandemic profile in the WPR, and several creative diagnostic and therapeutic measures undertaken. This includes drive-through screening facilities, high-speed RT-PCR technologies, convalescent patients' plasma therapy, which potentially had some positive contributions in combatting COVID-19 in the WPR as well as globally. Although the numbers of confirmed cases are currently decreasing in the region, the COVID-19 pandemic is not over, and many experts are recommending to prepare measures for potential second or third waves of COVID-19.