Okabayashi Ken, Kano Rui, Watanabe Shinichi, Hasegawa Atsuhiko
Department of Pathobiology, Nihon University School of Veterinary Medicine, 1866, Kameino, 252-8510, Fujisawa Kanagawa, Japan.
Mycopathologia. 2005 Aug;160(1):1-7. doi: 10.1007/s11046-005-0139-6.
Cryptococcus neoformans produces an extracellular polysaccharide capsule that is related to its virulence. The production of capsular components was reported to be accelerated when cultured on media with lower amount of glucose. In this study, relationship between capsule synthesis and expression of capsule-associated genes (CAP genes) was investigated by quantitative real-time PCR analysis. Normally encapsulated strains and a stable acapsular strain were cultured in 1% polypepton medium with 0.1% or 15% glucose. The results of assessment of the capsule size showed that the capsule of yeast cells cultured in the medium with low amount of glucose was thicker than that with high amount of glucose. The CAP gene expressions of normally encapsulated strains were higher in the medium with 0.1% glucose than in the medium with 15% glucose. Furthermore, CAP10, CAP59 and CAP60 genes were expressed very low in a stable acapsular strain, and CAP64 gene was not expressed. Results of assessment of capsule size and CAP gene expressions by quantitative real-time PCR analysis indicated that CAP gene expressions might be related to the production of capsule, and that glucose concentration in culture media might be related to the expression of CAP genes.
新型隐球菌产生一种与毒力相关的细胞外多糖荚膜。据报道，在葡萄糖含量较低的培养基上培养时，荚膜成分的产生会加速。在本研究中，通过定量实时PCR分析研究了荚膜合成与荚膜相关基因（CAP基因）表达之间的关系。将正常有荚膜菌株和稳定的无荚膜菌株在含有0.1%或15%葡萄糖的1%蛋白胨培养基中培养。荚膜大小评估结果表明，在低糖培养基中培养的酵母细胞的荚膜比在高糖培养基中培养的酵母细胞的荚膜更厚。正常有荚膜菌株的CAP基因在含0.1%葡萄糖的培养基中的表达高于在含15%葡萄糖的培养基中的表达。此外，CAP10、CAP59和CAP60基因在稳定的无荚膜菌株中表达极低，而CAP64基因不表达。通过定量实时PCR分析对荚膜大小和CAP基因表达的评估结果表明，CAP基因表达可能与荚膜的产生有关，并且培养基中的葡萄糖浓度可能与CAP基因的表达有关。
