The ‘king of fruits’ mango (Mangifera indica) is widely cultivated in tropical areas and has been threatened by frequent extreme cold weather. Cyclic nucleotide–gated ion channel (CNGC) genes have an important function in the calcium-mediated development and cold response of plants. However, few CNGC-related studies are reported in mango, regardless of the mango cold stress response. In this study, we identified 43 CNGC genes in mango showing tissue-specific expression patterns. Five MiCNGCs display more than 3-fold gene expression induction in the fruit peel and leaf under cold stress. Among these, MiCNGC9 and MiCNGC13 are significantly upregulated below 6 °C, suggesting their candidate functions under cold stress. Furthermore, cell membrane integrity was damaged at 2 °C in the mango leaf, as shown by the content of malondialdehyde (MDA), and eight MiCNGCs are positively correlated with MDA contents. The high correlation between MiCNGCs and MDA implies MiCNGCs might regulate cell membrane integrity by regulating MDA content. Together, these findings provide a valuable guideline for the functional characterization of CNGC genes and will benefit future studies related to cold stress and calcium transport in mango.

The effects of meteorological conditions on asthma in Haikou, a tropical city in China, are still unclear. This study aimed to determine the relationships between meteorological factors and the number of asthma hospital visits in Haikou. A Poisson generalized additive model combined with a distributed lag nonlinear model is used to model the nonlinear exposure–response relationship between the daily mean temperature and asthma hospital visits. The daily mean pressure and air quality are used as covariates and simultaneously control the mixed effects of holiday effects, weekend effects, and long-term trends. The results indicate that there is a significant statistical relationship between the daily mean temperature and asthma hospital visits, which shows an inverted J-shaped relationship. When the daily mean temperature is below the reference value (29.3 °C), the number of asthma patients increases considerably, and there is a marked lag in the prevalence of asthma. The longest lag is 9 days, and the most pronounced impact of the daily mean temperature on the number of asthma hospital visits can be found when the lag time is 1–4 days. When the daily mean temperature is 10 °C, the cumulative effect of the relative risk of asthma is 2.204, an increase of 120.4% (95% CI 1.294–3.755). If the daily mean temperature is below the 2.5th percentile value (14.8 °C), the relative risk significantly increases by more than 5.3% (95% CI 1.000–1.110), and the longest lasting impact time is 5 days. This indicates that increases in asthma hospital visits in Haikou, China, are significantly correlated with low-temperature weather. We suggest that preventive measures for asthma should take low-temperature weather into account. Additionally, we also found that extremely high temperatures have a certain impact on the increase in asthma hospital visits, but that the correlation is not significant.

Research on the impact of temperature in tropical regions on the risk of cardiovascular and cerebrovascular diseases was limited. The aim of the study was to investigate this topic using Haikou, a tropical city, as the research area. Outpatient data on cardiovascular and cerebrovascular diseases (CVD and CeVD) from Hainan Provincial People’s Hospital during 2016–2018 (total of 77,820) and meteorological and air-quality data were used to establish a distributed-lag nonlinear model (DLNM) based on the nested generalized addition model (GAM) of meteorological elements. The results revealed the impact on the risk of CVD and CeVD was mainly due to the cold effect, which significantly lagged behind. The thermal effect had a strong impact on the onset of CVD and CeVD on the day of high temperature. Males were easily affected by low temperatures, while females were the opposite. The lag period of the working-age group affected by low temperatures was longer and greater than that of the elderly group. The high-temperature effect only had an impact on the working-age group. The lag effect of low temperatures on the risk of hypertension was the greatest. These results can provide technical support for carrying out meteorological forecasting, warning, and services for individuals with CVD and CeVD, suggesting attaching importance to health protection for special populations.

Meteorological conditions and air quality are important environmental factors in the occurrence and development of cardiovascular diseases (CVDs) such as hypertension. The aim of this study was to take Haikou City, located on the tropical edge, as the research area and to analyze the exposure–response relationship and lag effect between its meteorological conditions, air quality, and the number of hypertensive patients. Using the data from the hypertension outpatient department of Hainan Provincial People’s Hospital from 2016 to 2018, together with meteorological data and air quality data, a distributed lag nonlinear model based on the nested generalized addition model of meteorological element base variables was established. The results showed that the impact of temperature on the risk of hypertension was mainly due to the cold effect, which was associated with high risk, with a lag of 1–10 days. When the temperature dropped to 10 °C, the cumulative effect on the risk of hypertension of relative risk (RR) reached its highest value on the day the low temperature occurred (RR was 2.30 and the 95% confidence interval was 1.723~3.061), passing the test with a significance level of 0.05. This result indicated that efforts should be made to strengthen the prevention of hypertension under low-temperature conditions and the prediction and early warning of disease risks. The impact of the air-quality effect (the environmental Air Quality Index was selected as an indicator) on the risk of hypertension was mainly characterized by a low air-quality effect, with a lag effect of 0–8 days. When the risk reached approximately 124, the RR was highest (RR was 1.63 and the 95% confidence interval was 1.104~2.408), passing the test with a significance level of 0.05. The research results can provide technical support for conducting medical meteorological forecasting, early warning, and services for hypertension. A joint work and research mechanism among multiple departments such as meteorology and medical health should be established to improve the level of medical and health care, optimize the allocation of social resources, and develop targeted prevention and control strategies to reduce the health and economic burden of hypertension.

This study aimed to investigate the effect of apparent temperature (AT) on hypertension outpatient visits in Haikou City and to establish a meteorological risk grade index for hypertension incidence. Based on daily data from September 2016 to April 2018, correlation analysis and a distributed lag nonlinear model were used to evaluate the association and lag effects between AT and the daily number of hypertension outpatient visits. The number of hypertension outpatient visits was significantly negatively correlated with AT. The cold effect (low AT) was predominant, exhibiting a significant lag and increasing the risk of outpatient visits, whereas the heat effect (high AT) was associated with a decreased risk. When the AT fell below 24.9°C, the risk increased as the temperature decreased; at 9.1°C, the same-day relative risk peaked (RR = 2.37, 95% CI: 1.771–3.173). When the AT exceeded 24.9°C, the risk decreased as the temperature increased; at 29.9°C, the relative risk was lowest (RR = 0.856, 95% CI: 0.741–0.989). Using the rate of increase in outpatient visits as an indicator, a risk grade index based on AT was established. The critical AT values for the high, relatively high, medium, and low risk levels were 11.07°C, 12.34°C, and 14.88°C, respectively. Subgroup analysis revealed that the effects of cold were stronger for males than for females, whereas the opposite pattern was observed for the effects of heat. The cold effect affected the juvenile group only on the day of exposure, whereas its effects on the working-age and elderly groups peaked on lag days 2 and 6, respectively. The heat effect affected only the working-age group. Low AT is an independent risk factor for hypertension outpatient visits in Haikou city, with a significant lag effect. The risk grade index based on AT provides a scientific basis for meteorological early warning and targeted prevention of hypertension in tropical regions.