Melanisation of Teladorsagia circumcincta larvae exposed to sunlight: a role for GTP-cyclohydrolase in nematode survival.

Trichostrongylid nematode parasites of livestock inhabit two very different niches during their life-cycle; within the host and free-living in the environment. UV radiation plays a significant role in the survival of free-living, pre-parasitic nematode larvae, with different species exhibiting differing levels of sensitivity. In many eukaryotes, melanisation is a key protective mechanism against UV damage, however there is little information about this process in parasitic nematodes.

GTP-cyclohydrolase and development in Teladorsagia circumcincta and Dictyocaulus viviparus (Nematoda: Strongylida).

GTP-Cyclohydrolase (GTP-CH) is necessary for the production of tetrahydrobiopterin, a required cofactor for the three aromatic amino acid hydroxylases and nitric oxide synthases. The gene encoding GTP-CH is transcribed at high levels in infective third larval stages of a number of parasitic trichostrongylid nematodes. We explore the potential role of GTP-CH within the processes of nematode development and environmentally-induced hypobiosis.