Environmental conditions,including ambient temperature,play important roles in survival,growth development,and reproduction of the Japanese sea cucumber,A postichopus japonicus. Low temperatures result in slowed growth and skin ulceration disease. In a previous study,we investigated the effect of low temperature on gene expression profiles in A. japonicus by suppression subtractive hybridization(SSH). Genes encoding Ferritin,Lysozyme,Hsp70,gp96,and AjToll were selected from a subtracted cDNA library of A. japonicus under acute cold stress. The transcriptional expression profiles of these genes were investigated in different tissues(coelomocyte,respiratory tree,intestine,longitudinal muscle) after exposure to acute and mild temperature dropping treatments. The results show that(1) the five cold-tolerance-related genes were found in all four tissues and the highest mRNA levels were observed in coelomocyte and respiratory tree;(2) under the temperature dropping treatments,three types of transcriptional regulation patterns were observed: primary suppression followed by up-regulation at-2°C,suppressed expression throughout the two treatments,and more rarely an initial stimulation followed by suppression; and(3) gene expression suppression was more severe under acute temperature dropping than under mild temperature dropping treatment. The five cold-tolerance-related genes that were distributed mainly in coelomocyte and respiratory tissues were generally down-regulated by low temperature stress but an inverse up-regulation event was found at the extreme temperature(-2°C). Environmental conditions, including ambient temperature, play important roles in survival, growth development, and reproduction of the Japanese sea cucumber, A postichopus japonicus. Low temperatures result in slowed growth and skin ulceration disease. In a previous study, we investigated the effect of low temperature on gene expression profiles in A. japonicus by suppression subtractive hybridization (SSH). Genes encoding Ferritin, Lysozyme, Hsp70, gp96, and AjToll were selected from a subtracted cDNA library of A. japonicus under acute cold stress. The transcriptional expression profiles of these genes were investigated in different tissues (coelomocyte, respiratory tree, intestine, longitudinal muscle) after exposure to acute and mild temperature dropping treatments. The results show that (1) the five cold-tolerance-related genes were found in all four tissues and the highest mRNA levels were observed in coelomocyte and respiratory tree; (2) under the temperature dropping treatments, three types of t ranscriptional regulation patterns were observed: primary suppression followed by up-regulation at-2 ° C, suppressed expression throughout the two treatments, and more rarely an initial stimulation followed by suppression; and (3) gene expression suppression was more severe under acute temperature dropping than under mild temperature dropping treatment. The five cold-tolerance-related genes that were distributed mainly in coelomocyte and respiratory tissues were down-regulated by low temperature stress but an inverse up-regulation event was found at the extreme temperature (-2 ° C).