Effects of local Polynesian plants and algae on growth and expression of two immune-related genes in orbicular batfish ( Platax orbicularis )

Abstract

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 - Lys G and transforming growth factor beta - TGF-β1) were studied to analyze immunostimulant activity of plants on P. orbicularis. Results showed that several plants increased Lys G and TGF-β1 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-β1 transcripts in kidney and spleen of P. orbicularis.

Dual RNAseq highlights the kinetics of skin microbiome and fish host responsiveness to bacterial infection

“…Eggs were randomly distributed into six black circular fiberglass tanks of 210 L with 50 eggs.L -1 in order to achieve an average density of 30 larvae.L -1 . Half of the tank were then reared in conditions that followed standard procedures implemented in the CIP facility (open water system, normal salinity around 36 psu), named "Standard" [18]. The other half was reared in conditions that were supposed to be optimal according to previous experiments, named "Recirculated".…”

“…before being weaned from day 16 to 23. Fingerlings were then fed with commercial micropellets ranging from 0,3 to 1 mm for the range Micro-Gemma and Gemma (Skretting, Stavanger, Norway) and 1-1.3 mm for Ridley (Le Gouessant, Lamballe, France) according to the standard previously established [18]. Seawater provided to both systems was pumped from the lagoon, filtered with 300 µm sand filter and two 25 and 10 µm mesh filters and UV treated (300 mJ/cm²).…”

“…Tenacibaculum maritimum is a worldwide-distributed fish pathogen, known for its lethal consequences on a broad range of wild and farmed marine fish populations. Major efforts have been undertaken to lessen the effect of the pathogen and/or increase fish immune resistance [18], yet the mechanisms of the infection and the response of fish remain largely unknown which significantly hold back development of aquaculture sectors. Nevertheless, recent sequencing of T. maritimum strain NCIMB 2154 T genome provided unprecedented information on the putative molecular mechanisms involved in virulence [19].…”

Macroalgal diversity for sustainable biotechnological development in French tropical overseas territories

“…These algae or seaweed extracts are used either to replace proteins of animal origin or for their prebiotic or anti-microbial effects, usually in the context of Integrated Multi-Trophic Aquaculture (IMTA) projects. Reverter et al (2016) studied the effects of local Polynesian plants and the red alga Asparagopsis taxiformis on the orbicular batfish when orally administered. Weight gain and expression of two immune-related genes (i.e.…”

“…lysozyme G and transforming growth factor beta-TGF-β1) were studied to analyze immunostimulant activity on orbicular batfish (Platax orbicularis Forsskäl). Asparagopsis taxiformis was the organism displaying the most promising results, promoting a weight gain of 24% after three weeks of oral administration and significantly increased the relative amount of both Lys G and TGF-β1 transcripts in the kidney and spleen of the fish (Reverter et al 2016).…”