Effects of local Polynesian plants and algae on growth and expression of two immune-related genes in orbicular batfish (Platax orbicularis)
Résumé
The emerging orbicular batfish (Platax orbicularis) aquaculture is the most important fish aquaculture
industry in French Polynesia. However, bacterial infections are causing severe mortality episodes.
Therefore, there is an urgent need to find an effective management solution. Besides the supplying
difficulty and high costs of veterinary drugs in French Polynesia, batfish aquaculture takes place close to
the coral reef, where use of synthetic persistent drugs should be restricted. Medicinal plants and
bioactive algae are emerging as a cheaper and more sustainable alternative to chemical drugs. We have
studied the effect of local Polynesian plants and the local opportunistic algae Asparagopsis taxiformis on
batfish when orally administered. Weight gain and expression of two immune-related genes (lysozyme g
e Lys G and transforming growth factor beta - TGF-b1) were studied to analyze immunostimulant activity
of plants on P. orbicularis. Results showed that several plants increased Lys G and TGF-b1 expression
on orbicular batfish after 2 and 3 weeks of oral administration. A. taxiformis was the plant displaying the
most promising results, promoting a weight gain of 24% after 3 weeks of oral administration and
significantly increasing the relative amount of both Lys G and TGF-b1 transcripts in kidney and spleen of
P. orbicularis.