Recently, the question of whether vitamin D exerts an effect on the pathogenic process of infertility has become the centre of attention. There are some controversial conclusions on this issue. Based on previous studies, we sought to explore the difference of serum 25-hydroxyvitamin D , 1,25-dihydroxyvitamin D levels between infertile patients and fertile men, and to find the influence on semen quality. The analysis of serum 25-hydroxyvitamin D level showed no significant difference between infertile patients and fertile men. However, the levels of serum 1,25-dihydroxyvitamin D in oligospermia (P < 0.05), asthenospermia (P < 0.01), oligoasthenospermia (P < 0.05) and azoospermia (P < 0.01) patients were significantly lower than those in fertile men. Moreover, serum 1,25-dihydroxyvitamin D level was positively correlated with progressive motility and total sperm number in infertile patients. In addition, a positive correlation between serum prolactin and 1,25-dihydroxyvitamin D was observed in fertile men. Our results indicated that lower vitamin D could be a risk factor for poor semen quality in infertile men. The 1,25-dihydroxyvitamin D , as the biologically active form of vitamin D, may be more significant.

To increase the growth of industrial strains under environmental stress, the Saccharomyces cerevisiae BY4741 salt-tolerant strain Y00 that tolerates 1.2 M NaCl was cultured through nitroguanidine mutagenesis. The metabolomics and transcription data of Y00 were compared with those of the wild-type strain BY4741. The comparison identified two genes related to salt stress tolerance, cds1 and cho1. Modular assembly of cds1 and cho1 redistributed the membrane phospholipid component and decreased the ratio of anionic-to-zwitterionic phospholipid in strain Y03 that showed the highest salt tolerance. Therefore, significantly increased membrane potential and membrane integrity helped strain Y03 to resist salt stress (1.2 M NaCl). This study provides an effective membrane engineering strategy to enhance salt stress tolerance.

To enhance the growth performance of Saccharomyces cerevisiae under osmotic stress, mutant XCG001, which tolerates up to 1.5 M NaCl, was isolated through adaptive laboratory evolution (ALE). Comparisons of the transcriptome data of mutant XCG001 and the wild-type strain identified ELO2 as being associated with osmotic tolerance. In the ELO2 overexpression strain (XCG010), the contents of inositol phosphorylceramide (IPC; t18:0/26:0), mannosylinositol phosphorylceramide [MIPC; t18:0/22:0(2OH)], MIPC (d18:0/22:0), MIPC (d20:0/24:0), mannosyldiinositol phosphorylceramide [M(IP)2C; d20:0/26:0], M(IP)2C [t18:0/26:0(2OH)], and M(IP)2C [d20:0/26:0(2OH)] increased by 88.3 times, 167 times, 63.3 times, 23.9 times, 27.9 times, 114 times, and 208 times at 1.0 M NaCl, respectively, compared with the corresponding values of the control strain XCG002. As a result, the membrane integrity, cell growth, and cell survival rate of strain XCG010 increased by 24.4% ± 1.0%, 21.9% ± 1.5%, and 22.1% ± 1.1% at 1.0 M NaCl, respectively, compared with the corresponding values of the control strain XCG002 (wild-type strain with a control plasmid). These findings provided a novel strategy for engineering complex sphingolipids to enhance osmotic tolerance. IMPORTANCE This study demonstrated a novel strategy for the manipulation of membrane complex sphingolipids to enhance S. cerevisiae tolerance to osmotic stress. Elo2, a sphingolipid acyl chain elongase, was related to osmotic tolerance through transcriptome analysis of the wild-type strain and an osmosis-tolerant strain generated from ALE. Overexpression of ELO2 increased the content of complex sphingolipid with longer acyl chain; thus, membrane integrity and osmotic tolerance improved.