Mud crab, Scylla paramamosain is one of the most important crustacean species in global aquaculture. To determine the genetic basis of sex and growth-related traits in S. paramamosain , a high-density genetic linkage map with 16,701 single nucleotide polymorphisms (SNPs) was constructed using SLAF-seq and a full-sib family. The consensus map has 49 linkage groups, spanning 5,996.66 cM with an average marker-interval of 0.81 cM. A total of 516 SNP markers, including 8 female-specific SNPs segregated in two quantitative trait loci (QTLs) for phenotypic sex were located on LG32. The presence of female-specific SNP markers only on female linkage map, their segregation patterns and lower female: male recombination rate strongly suggest the conformation of a ZW/ZZ sex determination system in S. paramamosain . The QTLs of most (90%) growth-related traits were found within a small interval (25.18–33.74 cM) on LG46, highlighting the potential involvement of LG46 in growth. Four markers on LG46 were significantly associated with 10–16 growth-related traits. BW was only associated with marker 3846. Based on the annotation of transcriptome data, 11 and 2 candidate genes were identified within the QTL regions of sex and growth-related traits, respectively. The newly constructed high-density genetic linkage map with sex-specific SNPs, and the identified QTLs of sex- and growth-related traits serve as a valuable genetic resource and solid foundation for marker-assisted selection and genetic improvement of crustaceans.

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The aim of the present study was to investigate and compare the 24-hour intraocular pressure (IOP) rhythms in winter and summer in the healthy population of Shanghai, China.This is a cross-sectional study in which 24-hour IOP measurements were taken for all eligible healthy volunteers in winter and summer, respectively, and the temperature, hours of sunlight (sunlight time), and circulatory parameters, including heart rate, systolic blood pressure, and diastolic blood pressure, were also recorded. The 24-hour IOP curves and IOP parameters (mean, peak, trough, and fluctuation of IOP together with the diurnal-to-nocturnal IOP change) in winter and summer were obtained and compared. The magnitude of IOP changes from summer to winter was also calculated.A total of 29 participants (58 eyes), 14 (48.28%) male and 15 (51.72%) female, aged 43.66 ± 12.20 (19–61) years, were considered eligible for this study. Generally, IOP decreased progressively before noon, increased notably in the nocturnal period, and peaked at 12:00 am in winter and at 2:00 am in summer. The pattern of 24-hour IOP in winter and summer was significantly different (P = 0.002). The average IOPs from 4:00 pm to 8:00 am, except for 6:00 am, were significantly higher in winter (P < 0.05). However, no significant differences were shown after adjusting for temperature and/or sunlight time. From summer to winter, the extent of IOP increase was mostly around 0 to 3 mm Hg, and the IOPs increased more significantly in the nocturnal period than in the diurnal period (P = 0.05).The 24-hour IOP rhythms were different in winter and summer, with higher IOP level in winter. Temperature and sunlight time, which are independent of heart rate and blood pressure, affected the 24-hour IOP rhythms in healthy people in Shanghai, China. Further investigations are expected for the rhythm of some endogenous substance secretion and the inner mechanism of regulation of IOP.

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