Unveiling the effect of dietary essential oils supplementation in Sparus aurata gills and its efficiency against the infestation by Sparicotyle chrysophrii

Abstract

A microencapsulated feed additive composed by garlic, carvacrol and thymol essential oils (EOs) was evaluated regarding its protective effect in gills parasitized by Sparicotyle chrysophrii in Sparus aurata. A nutritional trial (65 days) followed by a cohabitation challenge with parasitized fish (39 days) were performed. Transcriptomic analysis by microarrays of gills of fish fed the EOs diet showed an up-regulation of genes related to biogenesis, vesicular transport and exocytosis, leukocyte-mediated immunity, oxidation–reduction and overall metabolism processes. The functional network obtained indicates a tissue-specific pro-inflammatory immune response arbitrated by degranulating acidophilic granulocytes, sustained by antioxidant and anti-inflammatory responses. The histochemical study of gills also showed an increase of carboxylate glycoproteins containing sialic acid in mucous and epithelial cells of fish fed the EOs diet, suggesting a mucosal defence mechanism through the modulation of mucin secretions. The outcomes of the in vivo challenge supported the transcriptomic results obtained from the nutritional trial, where a significant reduction of 78% in the abundance of S. chrysophrii total parasitation and a decrease in the prevalence of most parasitic developmental stages evaluated were observed in fish fed the EOs diet. These results suggest that the microencapsulation of garlic, carvacrol and thymol EOs could be considered an effective natural dietary strategy with antiparasitic properties against the ectoparasite S. chrysophrii.

Diet, Immunity, and Microbiota Interactions: An Integrative Analysis of the Intestine Transcriptional Response and Microbiota Modulation in Gilthead Seabream (Sparus aurata) Fed an Essential Oils-Based Functional Diet

“…In fact, the dietary supplementation of garlic or its bioactive compounds (18), carvacrol, and/or thymol (19) have been reported to increase the number of white blood cells and other immune parameters in several cultivated fish species. Similarly to our results, the activation of the degranulation transcriptional response of the neutrophils was previously observed in the gills of gilthead seabream fed the same EOs-supplemented diet and attributed to its increased defense capacity against a monogenean helminth parasite infection (9).…”

“…A basal (control) diet was formulated with high levels of marine-derived protein sources to contain 46% crude protein, 18% crude fat, and 21.5 MJ/kg gross energy ( Table 1 ) as described in Firmino et al ( 9 ). The second experimental diet was the control diet supplemented with 0.5% of the functional additive composed of a blend of microencapsulated garlic, carvacrol, and thymol synthetic EOs (AROTEC-G®, TECNOVIT-FARMFAES, S.L., Spain).…”

“…Detailed information and transcriptomic raw data are available at the Gene Expression Omnibus (GEO) public repository at the U.S. National Center for Biotechnology Information (NCBI), accession numbers GPL13442 and GSE159643 , respectively. The sampling labeling, hybridization, washes, and scanning were performed as described before ( 9 ). For this purpose, a one-color RNA labeling was used (Agilent One-Color RNA Spike-In Kit; Agilent Technologies, USA).…”

“…Formulation and proximate composition of the basal diet. H. sapiens and gilthead seabream species, protein BLAST was run, and the GeneCards (www.genecards.org) and UniProt (www.uniprot.org) databases were accessed as described in Firmino et al(9).…”

Carvacrol, Thymol, and Garlic Essential Oil Promote Skin Innate Immunity in Gilthead Seabream (Sparus aurata) Through the Multifactorial Modulation of the Secretory Pathway and Enhancement of Mucus Protective Capacity

“…In this context, the aim of the present study was to evaluate the inclusion of a functional feed additive composed by a blend of garlic essential oil, carvacrol, and thymol (the main bioactive compounds of Labiateae plants essential oils) in a standard ongrowing diet for gilthead seabream (Sparus aurata), assessing its effects on the skin transcriptional response, pathogenic bacterial growth capacity in skin mucus, and fish overall health condition. This species was chosen since it is the most important marine farmed fish species in the Mediterranean with an annual production of 85,385.1 t in 2018 and an economic value of 502,398,000 US$ (16); thus, improving health management strategies based on sustainable dietary approaches for this farmed species is of relevance for this growing industry.…”