Integrated alternative approaches to select feed-efficient rainbow trout families to enhance the plant protein utilization.

Improving feed utilization efficiency is a challenge in aquaculture. Therefore, we developed an indirect benchmark to use in selecting trout for improved efficiency of feed utilization on plant protein (soy)-based diets, with the long-term goal of reducing the cost of commercial trout production. We used a four-part integrative approach to identify feed efficient individuals among 1595 fish coming from 12 genetically selected families by establishing the phenotypic relationship between feed conversion ratio (FCR) and body weight variations using compensatory feeding regimes. Additionally, we examined the nutritional composition of fish filet for each efficiency phenotype during the compensatory regimen. Our findings showed that the fish with the lowest weight loss during a feed deprivation period and the highest weight gain during the refeeding period (FD-/RF +) demonstrated the lowest FCR (FCR = 0.99) and consisted of individuals from several lines. This finding confirms the possibility of improving feed efficiency in mixed lines. Although feeding period has an effect on nutritional composition of fillet, such selection criteria did not show an effect on groups. Overall, successful selection for the improvement of feed efficiency will have a broad application to commercial fish selective breeding programs, leading to increased aquaculture sustainability in the long run.

Extract of common mallow (Malvae sylvestris) enhances growth, immunity, and resistance of rainbow trout (Oncorhynchus mykiss) fingerlings against Yersinia ruckeri infection.

The dietary effects of a native medicinal plant from Iran, common mallow (Malvae sylvestris), was evaluated on growth performance, innate immune parameters, mucosal immune parameters, and resistance of rainbow trout (Oncorhynchus mykiss) against Yersinia ruckeri. Therefore, 360 fish (initial weight 10.42 ± 0.09 g) were randomly distributed into 12 fiberglass tanks. Experimental diets supplemented with 0 (as control- C), 1% (M1), 3% (M2) and 5% (M3) levels of M. sylvestris flowers extract were fed to the fish based on 3% of body weight for 8 weeks. At the terminal sampling, growth performance, liver and digestive enzymes activities, blood and mucosal immune responses were determined. Results showed that M2 and M3 had greater final weight, weight gain, SGR, survival rate and lower FCR; higher levels of total protein, albumin, globulin, and lower cortisol levels in comparison to control; 5% extract also lowered cholesterol and glucose levels as well as Lactate Dehydrogenase (LDH) activity. We reported higher values of hematocrit, hemoglobin, Mean Corpuscular Hemoglobin (MCH), Mean Corpuscular Volume (MCV), White Blood Cell (WBC), Red Blood Cell (RBC) and lymphocytes for treated groups. Innate immune responses (Alternative complement activity (ACH50) in M2 and M3 group, total Immunoglobulin (Ig) and lysozyme in M3), mucosal immune parameters (ACH50, total Ig for M2 and M3 group and lysozyme in all treated groups) were enhanced. Activities of digestive enzymes (protease in all treated groups, amylase for 3 and 5%, while lipase only for 5%) and lower activity of liver ALT enzyme in individuals treated with highest dose was observed. Overall results indicated that the extract can positively affect growth performance and immune responses of rainbow trout.

Finding the undiscovered roles of genes: an approach using mutual ranking of coexpressed genes and promoter architecture-case study: dual roles of thaumatin like proteins in biotic and abiotic stresses.

Regarding the possible multiple functions of a specific gene, finding the alternative roles of genes is a major challenge. Huge amount of available expression data and the central role of the promoter and its regulatory elements provide unique opportunely to address this issue. The question is that how the expression data and promoter analysis can be applied to uncover the different functions of a gene. A computational approach has been presented here by analysis of promoter regulatory elements, coexpressed gene as well as protein domain and prosite analysis. We applied our approach on Thaumatin like protein (TLP) as example. TLP is of group 5 of pathogenesis related proteins which their antifungal role has been proved previously. In contrast, Osmotin like proteins (OLPs) are basic form of TLPs with proved role only in abiotic stresses. We demonstrated the possible outstanding homolouges involving in both biotic and abiotic stresses by analyzing 300 coexpressed genes for each Arabidopsis TLP and OLP in biotic, abiotic, hormone, and light microarray experiments based on mutual ranking. In addition, promoter analysis was employed to detect transcription factor binding sites (TFBs) and their differences between OLPs and TLPs. A specific combination of five TFBs was found in all TLPs presenting the key structure in functional response of TLP to fungal stress. Interestingly, we found the fungal response TFBs in some of salt responsive OLPs, indicating the possible role of OLPs in biotic stresses. Thirteen TFBS were unique for all OLPs and some found in TLPs, proposing the possible role of these TLPs in abiotic stresses. Multivariate analysis showed the possibility of estimating models for distinguishing biotic and abiotic functions of TIPs based on promoter regulatory elements. This is the first report in identifying multiple roles of TLPs and OLPs in biotic and abiotic stresses. This study provides valuable clues for screening and discovering new genes with possible roles in tolerance against both biotic and abiotic stresses. Interestingly, principle component analysis showed that promoter regulatory elements of TLPs and OLPs are more variable than protein properties reinforcing the prominent role of promoter architecture in determining gene function alteration.