Heat shock and developmental expression of hsp83 in the filarial nematode Brugia pahangi

hsp83 was cloned from the filarial nematode Brugia pahangi. The mRNA was co nstitutively expressed at 37 degreesC in life cycle stages that live in the mammalian host (microfilariae and adult worms). Heat shock resulted in onl y a minimal increase in levels of transcription. A genomic copy of hsp83 wa s isolated and was shown to contain 11 introns while sequencing of the 5' u pstream region revealed several heat shock elements. Using a chloramphenico l acetyltransferase (CAT) reporter gene construct the expression of hsp83 f rom B. pahangi (Bp-hsp83) was studied by transfection of COS-7 cells. Simil ar to the expression pattern in the parasite, CAT activity was detected at 37 degreesC and was not influenced by heat shock. When the free-living nema tode Caenorhabditis elegans was transfected with the same construct, CAT ac tivity was not observed at normal growth temperatures (21 degreesC) or unde r moderate heat shock conditions (28 degreesC). However exposure to more se vere heat shock (35 degreesC) resulted in an increase in CAT activity. Thes e results suggest that Bp-hsp83 has a temperature threshold greater than or equal to 35 degreesC for expression.