RESUMO
The first gout attack in a hyperuricaemic patient may be regarded as a nucleation event which is caused by monosodium urate monohydrate (MSUM) deposition in the synovial fluid. The effect of Tailor-Made Inhibition (TMI) may be effective as drugs for the prevention of aberrant nucleation and crystallization. Therefore, the understanding of the underlying mechanisms in inhibiting the MSUM nucleation by TMI has proven to be of great significance. Yet most of the published studies about nucleation inhibition have tended to focus on simpler molecular models with a hydrogen-bonded acceptor and donor, which may be not suitable for the uric acid molecule with multiple hydrogen-bonded acceptors and donors under physiological conditions. Herein, the mechanisms of nucleation inhibition of MSUM were explored in a simulated biological environment (0.15 M Na+ and pH 7.40) in the presence and absence of TMI. And the evidence of nucleation inhibition by TMI in solution and the amorphous form of MSUM was investigated by HNMR, IR, Raman, PXRD, Dynamic light scattering (DLS), induction time measurements, and density functional theory (DFT) calculations. Results showed that the inhibition comes from a combination of kinetic and thermodynamic effects, with an impact of kinetics as the TMI inhibition effects far exceeded what could be accounted for by changes in usual factors of classical nucleation theory. The data demonstrated that the complex between urate and TMI disturbed the formation of two-dimensional sheets of sodion and purine rings parallel to the (011) plane and further impeded the formation of a three-dimensional structure with aromatic stacking interactions in solution. To our knowledge, the nucleation inhibition of TMI is achieved by suppressing interplanar stacking, which is a mechanism proposed for the first time.
RESUMO
Melon is an important agricultural and economic vegetable crop worldwide. The genetic male sterility mutant (ms-5) has a recessive nuclear gene that controls the male sterility germplasm. Male sterility could reduce the cost of F1 seed production in melon, but heterozygous fertile plants should be removed before pollination. In this study, bulked segregant analysis combined with specific length amplified fragment sequencing was applied to map the single nuclear male sterility recessive gene. A 30-kb candidate region on chromosome 9 located on scaffold 000048 and spanning 2,522,791 to 2,555,104 bp was identified and further confirmed by cleavage amplified polymorphic sequence markers based on parental line resequencing data and classical mapping of 252 F2 individuals. Gene prediction indicated that six annotated genes are present in the 30-kb candidate region. Quantitative RT-PCR revealed significant differences in the expression level of the LOC103498166 ABORTED MICROSPORES (AMS) gene in male-sterile lines (ms-5) and male-fertile (HM1-1) lines during the 2-mm (tetrad) and 5-mm (the first pollen mitosis) periods, and negative regulation of the AMS candidate gene transcription factor was also detected. Sequencing and cluster analysis of the AMS transcription factor revealed five single-nucleotide polymorphisms between the parental lines. The data presented herein suggest that the AMS transcription factor is a possible candidate gene for single nuclear male sterility in melon. The results of this study will help breeders to identify male-sterile and -fertile plants at seeding as marker-assisted selection methods, which would reduce the cost of seed production and improve the use of male-sterile lines in melon.
