[Maturation of Cordyceps sinensis associates with alterations of fungal expressions of multiple Ophiocordyceps sinensis mutants in stroma of Cordyceps sinensis].
OBJECTIVE
To examine maturational changes in expressions of Ophiocordyceps sinensis (O.sinensis) transition and transversion mutation genotypes  in Cordyceps sinensis (C.sinensis) stroma.


METHODS
MassARRAY single nucleotide polymorphism (SNP) matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrum genotyping was used, and 8 SNP extension primers were designed based on the scattered, multiple point  mutations of known sequences for the O.sinensis mutants within their internal transcribed spacer (ITS) segments. Of the extension primers, 5 (not capable of  distinguishing between the 2 AT-biased genotypes) located in rDNA ITS1 and ITS2 regions: 067721-211, 067721-240, 067721-477, 067721-531 and  067721-581. The other 3 extension primers located in 5.8S rDNA region: 067740-324, 067740-328 and 067740-360, to distinguish between the 2 AT-biased genotypes.


RESULTS
MS chromatograms at the 8 SNP sites showed dynamic alterations of mutant alleles in C.sinensis stroma. The allele for the  AT-biased genotypes at 067721-211 site showed higher peak height than its GC-biased counterpart in the premature C.sinensis stroma, but  disappeared with C.sinensis maturation. Chromatograms displayed not only the transition mutation alleles, but also transversion mutants. Some of the  transversion mutation alleles displayed higher peak heights than those for GC- and AT-biased alleles, but their peak heights and detection rates tended  to be decreased with C.sinensis maturation. When distinguishing between the 2 AT-biases, AB067744 and AB067740 genotype alleles co-existed in the  premature C.sinensis stroma. The allele peak height for AB067744 genotype was greatly decreased with C.sinensis maturation, while that for AB067740  genotype increased.


CONCLUSIONS
Co-existence of at least 5 transition and transversion mutant genotypes of O.sinensis and the dynamic changes in  their expressions in C.sinensis stroma along with C.sinensis maturation may be of extreme importance in C.sinensis stroma germination and maturation,  enabling C.sinensis to complete its life cycle.
Pharmanex Beijing Clinical Pharmacology Center, Beijing 100088, China.
Ling
L
Gao
Xiao-hong
XH
Li
Jian-qing
JQ
Zhao
Ji-hong
JH
Lu
Jia-gang
JG
Zhao
Jia-shi
JS
Zhu
D001483:Base Sequence; D032661:Cordyceps / Q000235:genetics* / Q000254:growth & development*; D004271:DNA, Fungal / Q000235:genetics*; D005838:Genotype; D008969:Molecular Sequence Data; D017354:Point Mutation; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004271:DNA, Fungal