A New IL6 Isoform in Chinese Soft-Shelled Turtle () Discovered: Its Regulation during Cold Stress and Infection.

The Chinese soft-shelled turtle () is a widely cultured commercial species in East and Southeast Asian countries. The turtles frequently suffer from acute cold stress during farming in China. Stress-induced factor such as Interleukin-6 (IL6) is a multifunctional molecule that plays important roles in innate and adaptive immune response. In the present study, we found that the turtle possessed two IL6 transcripts, where one IL6 transcript contained a signal peptide sequence (), while the other IL6 transcript () possessed no such signal peptide gene. To test any differential expression of the two isoforms during temperature and microbial stress, turtles were adapted to optimal environmental water temperature (25 °C), stressed by acute cooling for 24 h, followed with the challenge of (1.8 × 10 CFU) or (5.8 × 10 CFU). Gene characterization revealed that , a splicer without codons encoding a signal peptide and identical to the one predicted from genomic sequence, and , a splicer with codons encoding a signal peptide, were both present. Inducible expression was documented in primary spleen cells stimulated with ConA and poly I: C. The splenic and intestinal expression of and was increased in response to temperature stress and bacterial infection.