A team of researchers from the Federal University of Santa Maria and the State University of Santa Catarina in Brazil explored the use of marc (GPF) flour in diets of grass carp raised in the face of a disease. The researchers published details of their work in the magazine, aquaculture.
“The purpose of this study was to evaluate whether supplementation with GPF is able to reduce or prevent the impairment of cellular energy homeostasis in experimentally infected herbaceous carp with P. aeruginosa,”the researchers said.
The researchers found that the addition of 300 mg of pomace flour / kg of feed could alleviate the activities of creatine kinase (CK), adenylate kinase (AK), pyruvate kinase (PK) and lactate dehydrogenase (LDH) compared to other infected fish but results were not the same as those of the uninfected control group.
However, the GPF supplement has prevented alterations in the oxidative damage resulting from the disease, the researchers said.
“The use of 300 mg of GPF / kg of feed has exerted protective effects on branched energy metabolism linked to the metabolism of ATP reducing the impairment of cellular energy homeostasis; its effects can be mediated by prevention of the oxidation of the SH group,” they added.
Aquaculture and disease
Aquaculture production is a rapidly expanding industry with an average growth rate of 5.8% from 2000 to 2016, the researchers said. By 2016 it has generated about 80 million tons of food fish.
However, dependence on intensive farming practices to meet demand has triggered outbreaks of several pathogenic organisms including Pseudomonas aeruginosa, they said. The Gram-negative bacterium is a common pathogen found both in sweet and marine aquaculture, and in relation to the “Red skin disease,”which affects several species including Nile tilapia, Mozambique tilapia, silver catfish and herbivorous carp.
The disease is characterized by dark skin, ascites, gill rot, petechial haemorrhage and exophthalmia, they said. “The gills are the organ most affected by the P. aeruginosa infection, which has been observed to cause severe destruction of primary and secondary lamellae, edema, hyperplasia, telangiectasia and desquamation,” they added.
In fish, the phosphorylated transfer system plays a role in coupling the production and consumption of adenosine triphosphate (ATP), the researchers said. The process is fundamental to the “Bioenergetics and homeostasis” of organisms.
“The enzymes creatine kinase (CK), adenylate kinase (AK) and pyruvate kinase (PK) have been linked to the efficient transfer of high-energy phosphoryl and signal communication in the cell to maintain energy balance,”they said.
However, P. aeruginosa infection is thought to hinder cellular energy homeostasis by downregulating the activity of enzymes involved in the phosphoryl transfer network in the gills of infected fish, they said. That interaction adds to the “Pathophysiology of the disease.”
“The alteration of CK, AK and PK activities causes a rapid decrease in global ATP concentrations during P. aeruginosa infection, which contributes directly to the pathogenesis of fish disease and mortality,” they said. “In this sense, the search for treatments that reduce or prevent alterations of the phosphoryl transfer network could be considered an appropriate approach to avoid this situation and the consequent mortality of the fish.”
Why use pomace flour in aquaculture diets?
Use of vegetables or “natural”Additives such as essential oils have been a more recent approach to the prevention or limitation of bioenergetic dysfunctions related to a compromised phosphotransfer network, the researchers said.
Grape pomace is a bio-residue from wine production, they said. It has “Powerful immunomodulatory effects”On the immune function of herbaceous carp infected with P. aeruginosa, which appears to be related to resveratrol (RSV).
“In this regard, Bottari et al. (2015) revealed that RSV was able to avoid the inhibition of CK and AK brain activity during toxoplasmosis, abolishing the energy imbalance between ATP production and; use of ATP,” the researchers said.
“Our hypothesis is that the use of GPF can reduce or prevent the impairment of the cellular energy homeostasis caused by the P. aeruginosa infection,” they added.
Feed test details
During the food and disease challenge process, 120 young people received one of three diets, the researchers said. The fish were acclimatized for 10 days, received the feed for 60 days and then half of the fish was injected with a strain of P. aeruginosa.
The diets included a control diet and that diet with two levels of additive GPF at 150 mg or 300 mg / kg, they said. The GFP used was commercially available and the chemical composition of the GPF was checked.
“The animals were divided into six groups (AF, n = 6 per group, in triplicate) as follows: groups A and D received the basal diet (without GPF supplementation), groups B and E received a diet containing 150 mg of GPF / kg of feed, while groups C and F received a diet containing 300 mg of GPF / kg of feed,” tThe researchers said. “After 60 days, the groups from D to F were experimentally infected.”
Fifteen days after infection, a selection of fish was collected and their branched tissue was collected and checked “Measurements of parameters related to oxidative stress,” they said. The homogenates for “Measurements of the phosphoryl transfer network,” they were also analyzed to verify AK, PK and cytosolic activity and mitochondrial CK.
Lipid peroxidation, non-protein thiols (NPSH) and proteins (PSH) were measured together with the activity of CK, AK and PK. The branched levels of reactive oxygen species (ROS) and peroxidation of proteins and lipids were established and an MTT assay was completed.
The researchers discovered an interaction between the infection and the use of the GPF supplement on the cytosolic gill activity and mitochondrial CK. CK activity decreased in infected fish compared to uninfected fish, while infected fish in integrated 300 mg feed saw better activity.
“The infection caused by P. aeruginosa PA01 causes a branched bioenergetic dysfunction in the herbivorous carp, as observed in the gills of the experimentally infected silver catfish from this bacterium,” they said. “The most important finding revealed in the present study is that the food supplement with 300 mg of GPF / kg of feed improves the activity of enzymes belonging to the phosphotransfer network, which can contribute to an efficient intracellular energy communication between the synthesis and consumption of cellular ATP.”
“Furthermore, this improvement effect on the phosphotransfer network appears to be linked to the protective effects against oxidative damage,” they added.
The infected fish that received the 300 mg supplement also improved the responses for the branching activity of AK and PK compared to infected fish, but the level of activity was not as high as the fish in the control group, they said. researchers. LDH branchial was higher in infected fish than in fish in the fish control group or infected fish on the 300mg diet.
The TBARS and ROS gill levels had increased in infected fish, but both uninfected fish and those with the 300 mg diet avoided the increase, they said. The infection has also increased the oxidation levels of branched lipids (LOOH) for fish, while the 300 mg supplement has reduced the increase.
The carbonylation levels of branchial proteins have increased in infected fish, they said. Addition, “Integration with 300mg of GPF / kg of feed (group F) avoided the increase in protein carbonylation levels in experimentally infected fish with P. aeruginosa and the levels were similar to the control group (group A).”
They said that NPSH and PSH levels decreased for infected fish compared to fish in the control group. However, the addition of 300 mg of GPF allowed the fish to avoid falling.
by M. Baldissera, C. Souza, S. Descovi, C. Verdi, C. Zeppenfeld, A. da Silva, R. Santos, B. Baldisserotto