A spatial interpolation approach for environmental assessment of aquaculture effects on water quality of Pagasitikos Gulf (Eastern Mediterranean).

The impact of fish farming on the physicochemical and biological parameters of the water column was investigated between July and October 2021, in Pagasitikos Gulf. For this purpose, a sampling strategy based on Geographical Information System (GIS) was developed and a grid of 28 sampling stations was created for in situ measurements. The method of spatial interpolation and especially the Radial Basis Function (RBF) was used to estimate the spatial distribution of DO, chl α and nutrients by means of GIS. General Linear Model (GLM) analysis showed significant differences for all measured parameters except for NO3. Nutrients remained at low concentrations without exceeding the permitted limits for eutrophication and welfare of cultivated organisms. GIS exhibited high usefulness for data analysis, with further studies warranted for its optimization on applications related to the environmental impact of fish farming.

Recent Advances in Mycotoxin Determination in Fish Feed Ingredients.

Low-cost plant-based sources used in aquaculture diets are prone to the occurrence of animal feed contaminants, which may in certain conditions affect the quality and safety of aquafeeds. Mycotoxins, a toxic group of small organic molecules produced by fungi, comprise a frequently occurring plant-based feed contaminant in aquafeeds. Mycotoxin contamination can potentially cause significant mortality, reduced productivity, and higher disease susceptibility; thus, its timely detection is crucial to the aquaculture industry. The present review summarizes the methodological advances, developed mainly during the past decade, related to mycotoxin detection in aquafeed ingredients, namely analytical, chromatographic, and immunological methodologies, as well as the use of biosensors and spectroscopic methods which are becoming more prevalent. Rapid and accurate mycotoxin detection is and will continue to be crucial to the food industry, animal production, and the environment, resulting in further improvements and developments in mycotoxin detection techniques.

Malpigmentation of Common Sole (Solea solea) during Metamorphosis Is Associated with Differential Synaptic-Related Gene Expression.

In farmed flatfish, such as common sole, color disturbances are common. Dyschromia is a general term that includes the color defects on the blind and ocular sides of the fish. The purpose was to examine the difference in gene expression between normal pigmented and juveniles who present ambicoloration. The analysis was carried out with next-generation sequencing techniques and de novo assembly of the transcriptome. Transcripts that showed significant differences (FDR < 0.05) in the expression between the two groups, were related to those of zebrafish (Danio rerio), functionally identified, and classified into categories of the gene ontology. The results revealed that ambicolorated juveniles exhibit a divergent function, mainly of the central nervous system at the synaptic level, as well as the ionic channels. The close association of chromophore cells with the growth of nerve cells and the nervous system was recorded. The pathway, glutamate binding-activation of AMPA and NMDA receptors-long-term stimulation of postsynaptic potential-LTP (long term potentiation)-plasticity of synapses, appears to be affected. In addition, the development of synapses also seems to be affected by the interaction of the LGI (leucine-rich glioma inactivated) protein family with the ADAM (a disintegrin and metalloprotease) ones.

Hox Genes Polymorphism Depicts Developmental Disruption of Common Sole Eggs.

In sole aquaculture production, consistency in the quality of produced eggs throughout the year is unpredictable. Hox genes have a crucial role in controlling embryonic development and their genetic variation could alter the phenotype dramatically. In teleosts genome duplication led paralog hox genes to become diverged. Direct association of polymorphism in hoxa1a, hoxa2a & hoxa2b of Solea solea with egg viability indicates hoxa2b as a potential genetic marker. High Resolution Melt (HRM) analysis was carried out in 52 viable and 61 non-viable eggs collected at 54±6 hours post fertilization (hpf). Allelic and genotypic frequencies of polymorphism were analyzed and results illustrated a significantly increased risk for non-viability for minor alleles and their homozygous genotypes. Haplotype analysis demonstrated a significant recessive effect on the risk of non-viability, by increasing the odds of disrupting embryonic development up to three-fold. Phylogenetic analysis showed that the paralog genes hoxa2a and hoxa2b, are separated distinctly in two clades and presented a significant ω variation, revealing their diverged evolutionary rate.

Molecular cloning of four glutathione peroxidase (GPx) homologs and expression analysis during stress exposure of the marine teleost Sparus aurata.

Glutathione peroxidase (GPx; EC 1.11.1.9) is an important family of enzymes that protects organisms from oxidative damage. Four full-length GPx cDNAs were cloned and characterized by rapid amplification of cDNA ends polymerase chain reaction (RACE-PCR) from the liver of gilthead sea bream (Sparus aurata), an economically important species for Mediterranean aquaculture. Structural and functional annotations were performed for all paralogs, which suggested possible differences in function and subcellular localization. The phylogenetic analysis, based on the amino acid sequences, revealed four groups corresponding to teleostean GPx1a, GPx1b, GPx4a, and GPx4b and three groups for mammalian GPx1, GPx2 and GPx4. The tree topology indicated past duplication events for fish genes, unlike their mammalian homologs. Transcriptional analysis in ten tissues by reverse transcription quantitative polymerase chain reaction (RT-qPCR) evidenced a tissue-specific pattern for each GPx homolog. Fish experimental groups were exposed to stress factors such as fasting and confinement. Relative expression analysis in fish liver demonstrated that GPx1 genes were not regulated by dietary restriction; GPx4b was differentially expressed opposed to regularly fed fish. On the other hand, both GPx1 and GPx4 genes were up-regulated in fish post exposed to confinement, considered as a response to acute stress. The results underline the role of GPx genes as indicators of stress and welfare status in gilthead sea bream aquaculture.

A comparative presentation of implementation of ISO 22000 versus HACCP and FMEA in a small size Greek factory producing smoked trout: a case study.

ISO 22000 is the new standard bound to replace HACCP on issues related to food safety. Although several companies, especially the big ones, have either implemented or are on the point of implementing ISO 22000, there are many others which are rather timid and/or reluctant to implement it. The main reason behind that is the lack of information and the fear that the new standard is too demanding in terms of bureaucratic work. This paper aims at making a comparative presentation of how the two systems can be applied to a small smoked salmon producing company thereby facilitating the emergence of the differences. The main difference is that in ISO 22000 systems like Good Manufacturing Practice and Good Hygiene Practice are prerequisites thus leading to lower number of CCPs. In this case study for example, the number of CCPs dropped from eight (8) in HACCP to four (4) in ISO 22000. Furthermore, the Failure Mode and Effect Analysis was applied to the smoked trout manufacturing process in an attempt to calculate quantitatively the Risk Priority Number (RPN) and to find out whether it can be effectively correlated to ISO 22000 and/or HACCP. RPN was found to be higher than 130 for eight steps, in close agreement with HACCP, thereby indicating that corrective actions will have to be undertaken.

The response of digestive proteases to abrupt salinity decrease in the euryhaline sparid Sparus aurata L.

The response of the digestive proteases to abrupt salinity change was studied in juvenile gilthead sea bream (Sparus aurata) for 15 days after transfer from 33 per thousand to 21 per thousand. Salinity decrease affected significantly neither the activity of total acid proteases in stomach, nor the activities of total alkaline proteases and major serine proteases--trypsin and chymotrypsin--in the alkaline part of the intestine. The activity of the major proteases was significantly different between the alkaline segments of the intestine, with the posterior intestine presenting the highest activities followed by the pyloric caeca. This distribution pattern remained unaffected by salinity decrease. Notably, salinity change led to significant alterations in elastase and carboxypeptidase activity. The changes were more prominent in the upper part of the intestine (pyloric caeca and anterior intestine) than in the posterior intestine. In pyloric caeca significant alteration of carboxypeptidase A and B activities was observed, elastase changes were confined to anterior intestine together with alterations in carboxypeptidase B activity, while in posterior intestine the changes were restricted to carboxypeptidase A activity. The results are discussed in relation to the osmoregulatory action of the intestinal segments and dietary protein digestion.

Dual adaptation to sensory conflicts during whole-body rotations.

A dual adaptation paradigm was used in order to study the adaptation to two conditions of conflicting visual and kinesthetic and vestibular information. Adaptation was induced in humans by modifying visual information during whole-body rotations with the help of a virtual reality set-up. Real rotations' amplitudes were factored by a gain of 0.5 or 1.5. The two conditions were associated to a visual context cue. The aim of the experiment was to provide support for either the feedback or the feedforward model of adaptive states switch. Results show that subjects could adapt to the two conditions of conflict during whole-body rotations. However, the two conflict situations have been found to differ both in their motor dynamics and in their susceptibility to adaptation, as it seems that the adaptation is more complete in the condition of gain 1.5, i.e., faster and more precise. Subjects could be divided into two groups according to their ability to use contextual information to switch between adaptive gains. The visual cues were sufficient for some subjects to switch adaptive state, which corresponds to a context-dependent dual adaptation, or feedforward model of switching. Other subjects showed a switch cost maintained across the experiment, corresponding with a stimulus-dependent adaptation, or feedback model of switching. We are suggesting that the process enabling switching between adaptive states depends on subjects' abilities to use contextual cues of certain types, and thus on their "perceptive styles". This could explain the variability of results obtained in the literature.

The verbal fluency task in the Greek population: normative data, and clustering and switching strategies.

We assessed 300 healthy adults in Greece on measures of semantic and phonemic verbal fluency in order to develop norms for the Greek population. We also evaluated the strategies that the participants used spontaneously in order to maximize word production, namely clustering and switching techniques. Our tasks comprised three semantic and three phonemic categories. Consistent with previous investigations of English-speaking samples, we found a contribution of demographic variables to word fluency. Specifically, level of education contributed to total word production, number of switches, and number of repetitive responses on both semantic and phonemic tasks, and the average cluster size only on the phonemic task. Age contributed to total word production and cluster size on the semantic task, and to number of switches on both semantic and phonemic tasks. Sex contributed only to total word production on the semantic task. In our sample, clustering and switching strategies were related to total word production on both tasks, suggesting that these strategies were used effectively. We present tables of normative data stratified by age and level of education. We have also included detailed guidelines for scoring clusters relevant to the Greek population.