Effects of dietary substitution of fishmeal by black soldier fly (Hermetia illucens) meal on growth performance, whole-body chemical composition, and fatty acid profile of Pontastacus leptodactylus juveniles

Freshwater crayfish are considered as aquatic products of high quality and high nutritional value. The increasing demand has led to populations reduction in several locations throughout their range. Thus, the development of appropriate rearing conditions is considered necessary, among which, optimization of their diet is a basic part. Towards this direction, in the present study, a 98-day feeding trial was carried out to evaluate the impact of dietary fishmeal substitution by Hermetia illucens meal on Pontastacus leptodactylus juveniles kept under laboratory conditions. Insect meals represent an environmentally friendly alternative solution, considered as a high-value feed source, rich in nutrients such as protein and fat. Three dietary regimens were utilized with a fishmeal-based without Hermetia meal (HM) defined as the control diet (HM0), and two diets, the first with 50% (HM50) and the second with 100% (HM100) of fishmeal substitution by HM, respectively. Growth performance, whole-body composition, and fatty acid profiles of individuals were studied in the different treatments. At the end of the feeding trial, statistically significant differences were observed in the mean survival rate (SR), specific growth rate (SGR), feed conversion ratio (FCR) and weight gain (WG) values. More specifically, animals fed with HM-based diets had higher mean SR, while the control group performed better regarding FCR and SGR. The HM inclusion in the diet significantly altered the whole-body chemical composition of the crayfish signifying a different metabolic utilization compared to fishmeal (FM). The fatty acid analysis revealed that 16:0 (palmitic acid) was the predominant saturated fatty acid (SFA), 18:1ω9 (oleic acid) was found to be the main monounsaturated fatty acid (MUFA), while 18:2ω6 (linoleic acid) represented the major polyunsaturated fatty acid (PUFA) followed by C20:3 cis ω3 (cis-11-14-17-eicosatrienoate) and C22:6 cis ω3 (cis-4,7,10,13,16,19-Docosahexaenoic) fatty acids. The inclusion of dietary HM significantly reduced the contents of ∑SFAs, ∑PUFAs and ∑ω6 fatty acids, as well as those of C22:6 cis ω3 and increased the ω6/ω3 and hypocholesterolemic to hypercholesterolemic ratios in the body. In parallel with improvements in balanced diets and in culture conditions that need to be optimised for rearing of freshwater crayfish, our study provides new data that enlighten the suitability of insect meals in the nutrition of P. leptodactylus

The Coding Mitogenome of the Freshwater Crayfish <i>Pontastacus leptodactylus</i> (Decapoda:Astacidea:Astacidae) from Lake Vegoritida, Greece and Its Taxonomic Classification

Pontastacus leptodactylus (Eschscholtz, 1823) (Decapoda:Astacidea:Astacidae) constitutes an ecologically and economically highly important species. In the present study, the mitochondrial genome of the freshwater crayfish P. leptodactylus from Greece is analyzed for the first time, using 15 newly designed primer pairs based on available sequences of closely related species. The analyzed coding part of the mitochondrial genome of P. leptodactylus consists of 15,050 base pairs including 13 protein-coding genes (PCGs), 2 ribosomal RNA gene (rRNAs), and 22 transfer RNA genes (tRNAs). These newly designed primers may be particularly useful in future studies for analyzing different mitochondrial DNA segments. Based on the entire mitochondrial genome sequence, compared to other haplotypes from related species belonging in the same family (Astacidae) available in the GenBank database, a phylogenetic tree was constructed depicting the phylogenetic relationships of P. leptodactylus. Based on the results, the genetic distance between Astacus astacus and P. leptodactylus is smaller than the genetic distance between Austropotamobius pallipes and Austropotamobius torrentium, despite the fact that the latter two are classified within the same genus, questioning the phylogenetic position of A. astacus as a different genus than P. leptodactylus. In addition, the sample from Greece seems genetically distant compared with a conspecific haplotype available in the GenBank database, possibly implying a genetic distinction of P. leptodactylus from Greece

Antioxidant and DNA-Protective Activity of an Extract Originated from Kalamon Olives Debittering

Table olives are a major component of the Mediterranean diet and are associated with many beneficial biological activities, which are mainly related to their phenolic compounds. Olive fruit debittering process defines the quantitative and qualitative composition of table olives in biophenols. The aim of the present study was to evaluate the in vitro antioxidant capacity and DNA-protective activity of an extract originated from brine samples, according to the Greek style debbitering process of Kalamon olive fruits. The main phenolic components determined in the brine extract were hydroxytyrosol (HT), verbascoside (VERB) and tyrosol (T). The in vitro cell-free assays showed strong radical scavenging capacity from the extract, therefore antioxidant potential. At cellular level, human endothelial cells (EA.hy296) and murine myoblasts (C2C12) were treated with non-cytotoxic concentrations of the brine extract and the redox status was assessed by measuring glutathione (GSH), reactive oxygen species (ROS) and lipid peroxidation levels (TBARS). Our results show cell type specific response, exerting a hormetic reflection at endothelial cells. Finally, in both cell lines, pre-treatment with brine extract protected from H2O2-induced DNA damage. In conclusion, this is the first holistic approach highlighted table olive wastewaters from Kalamon- Greek style debittering process, as valuable source of bioactive compounds, which could have interesting implications for the development of new products in food or other industries

First detection of Aphanomyces astaci and its potential responsibility for mass mortalities of Pontastacus (Astacus) leptodactylus in Greek lakes

Aphanomyces astaci is a pathogen categorized among the 100 worst invasive alien species, responsible for the crayfish plague disease. In the past, many disease outbreaks devastated native European crayfish populations. The pathogen was transferred in Europe by its natural carriers, among which is the North American crayfish species Pacifastacus leniusculus, that has been introduced in Greece during 1980s. On the other hand, Pontastacus leptodactylus represents an indigenous species in Greece and apart from being keystone organism constitutes a valuable food source. Here, we investigated populations from lakes Volvi, Polifitou and Vegoritida for the pathogen’s presence after the mass mortalities observed from local fishermen in the two of them, namely, Vegoritida and Polifitou. All samples from these two lakes were positive, verifying the pathogen presence for the first time in Greece. On the other hand, all examined Pacifastacus leniusculus individuals were surprisingly negative, despite the expected hypothesis that they could be the reason for the spread of the pathogen in Greece. The unfavorable environmental conditions observed this year in combination with the improper management practices may led to massive reduction of crayfish populations in lakes Vegoritida and Polifitou. Thus, there is an urgent need for deeper investigations to unveil the leading cause of the disease outbreak in order to design and propose proper management measurements

Antioxidant and DNA-Protective Activity of an Extract Originated from Kalamon Olives Debittering

Table olives are a major component of the Mediterranean diet and are associated with many beneficial biological activities, which are mainly related to their phenolic compounds. Olive fruit debittering process defines the quantitative and qualitative composition of table olives in biophenols. The aim of the present study was to evaluate the in vitro antioxidant capacity and DNA-protective activity of an extract originated from brine samples, according to the Greek style debbitering process of Kalamon olive fruits. The main phenolic components determined in the brine extract were hydroxytyrosol (HT), verbascoside (VERB) and tyrosol (T). The in vitro cell-free assays showed strong radical scavenging capacity from the extract, therefore antioxidant potential. At cellular level, human endothelial cells (EA.hy296) and murine myoblasts (C2C12) were treated with non-cytotoxic concentrations of the brine extract and the redox status was assessed by measuring glutathione (GSH), reactive oxygen species (ROS) and lipid peroxidation levels (TBARS). Our results show cell type specific response, exerting a hormetic reflection at endothelial cells. Finally, in both cell lines, pre-treatment with brine extract protected from H2O2-induced DNA damage. In conclusion, this is the first holistic approach highlighted table olive wastewaters from Kalamon- Greek style debittering process, as valuable source of bioactive compounds, which could have interesting implications for the development of new products in food or other industries

Aquaponics as a Promising Strategy to Mitigate Impacts of Climate Change on Rainbow Trout Culture

The impact of climate change on both terrestrial and aquatic ecosystems tends to become more progressively pronounced and devastating over the years. The sector of aquaculture is severely affected by natural abiotic factors, on account of climate change, that lead to various undesirable phenomena, including aquatic species mortalities and decreased productivity owing to oxidative and thermal stress of the reared organisms. Novel innovative technologies, such as aquaponics that are based on the co-cultivation of freshwater fish with plants in a sustainable manner under the context of controlled abiotic factors, represent a promising tool for mitigating the effect of climate change on reared fish. The rainbow trout (Oncorhynchus mykiss) constitutes one of the major freshwater-reared fish species, contributing to the national economies of numerous countries, and more specifically, to regional development, supporting mountainous areas of low productivity. However, it is highly vulnerable to climate change effects, mainly due to the concrete raceways, in which it is reared, that are constructed on the flow-through of rivers and are, therefore, dependent on water’s physical properties. The current review study evaluates the suitability, progress, and challenges of developing innovative and sustainable aquaponic systems to rear rainbow trout in combination with the cultivation of plants. Although not commercially developed to a great extent yet, research has shown that the rainbow trout is a valuable experimental model for aquaponics that may be also commercially exploited in the future. In particular, abiotic factors required in rainbow trout farming along, with the high protein proportion required in the ratios due to the strict carnivorous feeding behavior, result in high nitrate production that can be utilized by plants as a source of nitrogen in an aquaponic system. Intensive farming of rainbow trout in aquaponic systems can be controlled using digital monitoring of the system parameters, mitigating the obstacles originating from extreme temperature fluctuations

Determination of Redox Status in Different Tissues of Lambs and Kids and Their in-between Relationship

The objective of this study was to assess the resting values of the physiological oxidative stress exhibited by lambs and kids reared in Greece, and the potential correlations between redox biomarker levels in blood and other tissues (liver, diaphragm, quadriceps, psoas major muscle). For this purpose, lambs and kids at different developmental stages (d.s.) were used. The latter corresponded to four live weight categories (LWC), each representing 25%, 35%, 70% and 100% of mature body weight. In each of the above tissues, the levels of five common redox biomarkers were determined: glutathione (GSH), catalase (CAT), total antioxidant capacity (TAC), thiobarbituric reactive substances (TBARS), and protein carbonyls (CARBS). The results revealed that lambs and kids belonging to the 35% LWC had weaker endogenous antioxidant pools, while animals in the 70% and 100% LWC had elevated intrinsic antioxidant defense systems. Blood redox biomarkers were associated with the respective ones measured in the diaphragm, liver, quadriceps, and psoas major of both species. Importantly, TBARS levels in blood of animals in the 25% and 100% LWC are correlated with the TBARS levels in all other tissues tested. Blood antioxidant parameters might be used as potential biomarkers to predict the antioxidant status of tissues that affect meat quality. The latter would facilitate quality assessment prior to slaughter, allowing for timely nutritional interventions that can improve meat products

Prevalence of Antibiotic Resistant <i>E. coli</i> Strains Isolated from Farmed Broilers and Hens in Greece, Based on Phenotypic and Molecular Analyses

The use of antimicrobials is beneficial for livestock health; however, their overuse and misuse may increase resistance to these compounds. Thus, the aim of the present study was the phenotypic and molecular examination of the presence of Escherichia coli antibiotic-resistant strains in broiler and laying hen farms. The resistance of E. coli strains was examined against various antibiotics, including several families of compounds such as penicillin class medications (ampicillin), cephalosporins (cefotaxime, cefoxitin, cefpodoxime and ceftazidime), sulfonamides (co-trimoxazole), quinolones (enrofloxacin and nalidixic acid), aminoglycosides (gentamicin), β-lactams (imipenem), aminoglycoside (streptomycin), and polymyxin (colistin). In total, 106 strains were investigated, sampled during the years 2016–2019 from 91 poultry farms, including 75 broiler farms and 16 laying hen farms, originating from three Regional Units in Greece. The examined isolates revealed the highest resistance rates to sulfamethoxazole (81.1%), nalidixic acid (73.6%), tetracyclin (70.8%), and streptomycin (70.8%). On the other hand, the resistance of the isolates to third generation cephalosporins was found to be at lower levels for ceftazidime (2.8%), ceftriaxone (3.7%) cefoxitin (4.7%), and cefotaxime (4.7%). Phenotypic tests showed that 13.6% and 10.2% of the isolates produced ESBL, while 2.7% and 1% produced AmpC b-lactamase, for broiler and laying hens, respectively. The prevalence of the mcr-1 gene was found to be 22.7%, detected only in broiler isolates. Based on our results, E. coli antibiotic resistance represents a critical control point in poultry production that, apart from farm animals, may affect public health as well