Expression Patterns of Three Genes Under Short and Long Term Cold Exposure in Thitarodes pui (Lepidoptera: Hepialidae), A Host of Ophiocordyceps sinensis

　　BACKGROUND: Thitarodes larvae are the host of the caterpillar fungus Ophiocordyceps sinensis. Low temperature is the main environmental limitation for larvae growth.

OBJECTIVE

To better understand the cold adaption process in T. pui larvae, the expression patterns of trehalose-6-phosphate synthase (TpTPS), heat shock protein 70 (TpHSP70), and heat shock protein 90 (TpHSP90) were investigated upon short and long-term exposure to 0°C.

MATERIALS AND METHODS

The 6th instar T. pui larvae were collected in July 2013. TpTPS was firstly sequenced and expression patterns of TpTPS, TpHSP70 and TpHSP90 were investigated using quantitative PCR.

RESULTS

Full-length cDNA of TpTPS was 3,012 bp, with an open reading frame of 2,472 bp and an encoding protein of 823 amino acids. TpTPS up-regulation was induced by cold exposure. TpHSP70 expression is altered by cold exposure, but remained low. TpHSP90 expression was obviously up regulated in long-term cold stimulation.

CONCLUSION

All three genes (TpTPS, TpHSP70 and TpHSP90) have likely contributed to cold tolerance in T. pui larvae, TpTPS and TpHSP90 potentially being more important.

Single-nucleotide polymorphism identification in the caprine myostatin gene

Polymerase chain reaction (PCR) products of MSTN gene amplified from 35 goats representing 17 Chinese indigenous goat breeds and five imported goat breeds were sequenced to identify the single-nucleotide polymorphisms (SNPs) of a 379-bp fragment including part of intron 2 and exon 3 of MSTN gene. A total of eight SNPs (A1980G, G1981C, A1982G, G1984T, A2121G, T2124C, G2174A and A2246G) were identified among the sequenced goats. The SNPs found are all located in intron 2 except for A2246G, which was a synonymous mutation in exon 3. Four haplotypes were sorted from these eight SNPs, of which, haplotype I (AGAGATGA) and haplotype II (GCGTGTAA) are the two main haplotypes with the frequency of 77.8% and 14.8% respectively. The SNPs found at positions 1980, 1981, 1982, 1984 and 2121 might be linked to inheritance completely.