Constantina Kokkari

@article{skliros_unveiling_2024,

title = {Unveiling Emerging Opportunistic Fish Pathogens in Aquaculture: A Comprehensive Seasonal Study of Microbial Composition in Mediterranean Fish Hatcheries},

author = {Dimitrios Skliros and Maria Kostakou and Constantina Kokkari and Maria Ioanna Tsertou and Christina Pavloudi and Haris Zafeiropoulos and Pantelis Katharios and Emmanouil Flemetakis},

url = {https://www.mdpi.com/2076-2607/12/11/2281

https://imbbc.hcmr.gr/wp-content/uploads/2024/11/2024-Skliros-microorganisms-45.pdf},

doi = {10.3390/microorganisms12112281},

issn = {2076-2607},

year  = {2024},

date = {2024-11-12},

urldate = {2024-11-12},

journal = {Microorganisms},

volume = {12},

number = {11},

pages = {2281},

abstract = {The importance of microbial communities in fish hatcheries for fish health and welfare has been recognized, with several studies mapping these communities during healthy rearing conditions and disease outbreaks. In this study, we analyzed the bacteriome of the live feeds, such as microalgae, rotifers, and Artemia, used in fish hatcheries that produce Mediterranean species. Our goal was to provide baseline information about their structure, emphasizing in environmental putative fish pathogenic bacteria. We conducted 16S rRNA amplicon Novaseq sequencing for our analysis, and we inferred 46,745 taxonomically annotated ASVs. Results showed that incoming environmental water plays a significant role in the presence of important taxa that constitute presumptive pathogens. Bio-statistical analyses revealed a relatively stable bacteriome among seasonal samplings for every hatchery but a diverse bacteriome between sampling stations and a distinct core bacteriome for each hatchery. Analysis of putative opportunistic fish pathogenic genera revealed some co-occurrence correlation events and a high average relative abundance of Vibrio, Tenacibaculum, and Photobacterium genera in live feeds, reaching a grand mean average of up to 7.3% for the hatchery of the Hellenic Center of Marine Research (HCMR), 12% for Hatchery A, and 11.5% for Hatchery B. Mapping the bacteriome in live feeds is pivotal for understanding the marine environment and distinct aquaculture practices and can guide improvements in hatchery management, enhancing fish health and sustainability in the Mediterranean region.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tsertou_isolation_2023,

title = {Isolation and characterization of a novel Tenacibaculum species and a corresponding bacteriophage from a Mediterranean fish hatchery: Description of Tenacibaculum larymnensis sp. nov. and Tenacibaculum phage Larrie},

author = {Maria Ioanna Tsertou and Adriana Triga and Stavros Droubogiannis and Constantina Kokkari and Grammatiki Anasi and Pantelis Katharios},

url = {https://imbbc.hcmr.gr/wp-content/uploads/2023/03/2023-Tsertou-FroMicro-13.pdf

https://www.frontiersin.org/articles/10.3389/fmicb.2023.1078669/full},

doi = {10.3389/fmicb.2023.1078669},

issn = {1664-302X},

year  = {2023},

date = {2023-03-07},

urldate = {2023-03-07},

journal = {Frontiers in Microbiology},

volume = {14},

pages = {1078669},

abstract = {Tenacibaculum larymnensis 

 sp. nov., a novel species of the 

 Tenacibaculum 

 genus was isolated from a commercial fish hatchery in Greece. The novel species is phylogenetically close to 

 T. discolor 

 and was biochemically and genetically characterized. The genome of 

 T 

 . 

 larymnensis 

 has 3.66 Mbps length, 31.83% GC content and the genomic analysis demonstrated that it harbors a wide enzymatic repertoire suggestive of increased degrading capacity but also several virulence factors including hemolysins, secretion systems, transporters, siderophores, pili and extracellular proteins. Using the novel strain, a virulent bacteriophage designated as Tenacibaculum phage Larrie was isolated and characterized. Larrie is a novel Siphovirus with relatively large genome, 77.5 kbps with 111 ORFs, a GC content of 33.7% and an exclusively lytic lifestyle. The new phage-host system can serve as an efficient model to study microbial interactions in the aquatic environment which contribute to the nutrient cycling.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_fish_2022,

title = {A fish kill at the Aposelemis dam (Crete, Greece) caused by heavy parasitism by textitIchthyobodo sp.},

author = {Pantelis Katharios and Constantina Kokkari and Maria Chiara Cascarano and Stylianos Gyparakis and Chrissi Aggelidaki and Ioanna Antonakaki and Efthimia Vargiakaki},

url = {https://imbbc.hcmr.gr/wp-content/uploads/2022/09/2022-Katharios-Journal-of-Fish-Diseases-2022-Katharios-A-fish-kill-at-the-Aposelemis-dam-Crete-Greece-caused-by-heavy-parasitism-63.pdf

https://onlinelibrary.wiley.com/doi/10.1111/jfd.13717},

doi = {10.1111/jfd.13717},

issn = {0140-7775, 1365-2761},

year  = {2022},

date = {2022-09-01},

urldate = {2022-09-26},

journal = {Journal of Fish Diseases},

pages = {jfd.13717},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{droubogiannis_vibrio_2022,

title = {Vibrio Phage Artemius, a Novel Phage Infecting Vibrio alginolyticus},

author = {Stavros Droubogiannis and Lydia Pavlidi and Maria Ioanna Tsertou and Constantina Kokkari and Dimitrios Skliros and Emmanouil Flemetakis and Pantelis Katharios},

url = {https://imbbc.hcmr.gr/wp-content/uploads/2022/07/2022-Droubogiannis-pathogen-54.pdf

https://www.mdpi.com/2076-0817/11/8/848},

doi = {10.3390/pathogens11080848},

issn = {2076-0817},

year  = {2022},

date = {2022-01-01},

urldate = {2022-07-29},

journal = {Pathogens},

volume = {11},

number = {8},

pages = {848},

abstract = {Vibrio alginolyticus is an important pathogen of marine animals and has been the target of phage therapy applications in marine aquaculture for many years. Here, we report the isolation and partial characterization of a novel species of the Siphoviridae family, the Vibrio phage Artemius. The novel phage was species-specific and could only infect strains of V. alginolyticus. It could efficiently reduce the growth of the host bacterium at various multiplicities of infection as assessed by an in vitro lysis assay. It had a genome length of 43,349 base pairs. The complete genome has double-stranded DNA with a G + C content of 43.61%. In total, 57 ORFs were identified, of which 19 were assigned a predicted function. A genomic analysis indicated that Vibrio phage Artemius is lytic and does not harbor genes encoding toxins and antibiotic resistance determinants.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{skliros_development_2021,

title = {The Development of Bacteriophage Resistance in Vibrio alginolyticus Depends on a Complex Metabolic Adaptation Strategy},

author = {Dimitrios Skliros and Panos G Kalatzis and Chrysanthi Kalloniati and Fotios Komaitis and Sokratis Papathanasiou and Evangelia D Kouri and Michael K Udvardi and Constantina Kokkari and Pantelis Katharios and Emmanouil Flemetakis},

url = {https://www.mdpi.com/1999-4915/13/4/656

https://imbbc.hcmr.gr/wp-content/uploads/2021/05/2021-Sκliros-viruses-29-1.pdf},

doi = {10.3390/v13040656},

year  = {2021},

date = {2021-04-01},

urldate = {2021-04-27},

journal = {Viruses},

volume = {13},

number = {4},

pages = {656},

abstract = {Lytic bacteriophages have been well documented to play a pivotal role in microbial ecology due to their complex interactions with bacterial species, especially in aquatic habitats. Although the use of phages as antimicrobial agents, known as phage therapy, in the aquatic environment has been increasing, recent research has revealed drawbacks due to the development of phage-resistant strains among Gram-negative species. Acquired phage resistance in marine Vibrios has been proven to be a very complicated process utilizing biochemical, metabolic, and molecular adaptation strategies. The results of our multi-omics approach, incorporating transcriptome and metabolome analyses of Vibrio alginolyticus phage-resistant strains, corroborate this prospect. Our results provide insights into phage-tolerant strains diminishing the expression of phage receptors ompF, lamB, and btuB. The same pattern was observed for genes encoding natural nutrient channels, such as rbsA, ptsG, tryP, livH, lysE, and hisp, meaning that the cell needs to readjust its biochemistry to achieve phage resistance. The results showed reprogramming of bacterial metabolism by transcript regulations in key-metabolic pathways, such as the tricarboxylic acid cycle (TCA) and lysine biosynthesis, as well as the content of intracellular metabolites belonging to processes that could also significantly affect the cell physiology. Finally, SNP analysis in resistant strains revealed no evidence of amino acid alterations in the studied putative bacterial phage receptors, but several SNPs were detected in genes involved in transcriptional regulation. This phenomenon appears to be a phage-specific, fine-tuned metabolic engineering, imposed by the different phage genera the bacteria have interacted with, updating the role of lytic phages in microbial marine ecology.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kokou_surplus_2020,

title = {Surplus of dietary micronutrients promotes antioxidant defense and improves fin erosions in European seabass (Dicentrarchus labrax) fry},

author = {Fotini Kokou and Roberto Bastias and Konstantina Kokkari and Pantelis Katharios and Efthimia Cotou and Nikos Seimenis and Manolis Vasilakis and Nikos Papandroulakis and Morgane Henry and George Rigos},

url = {http://www.sciencedirect.com/science/article/pii/S0044848619330868},

doi = {https://doi.org/10.1016/j.aquaculture.2020.735224},

issn = {0044-8486},

year  = {2020},

date = {2020-01-01},

journal = {Aquaculture},

volume = {523},

pages = {735224},

abstract = {Dietary micronutrient supplementation can serve as skin health promotor to prevent from natural infections and can be applied to decrease the use of antibacterial agents and their impact on the environment. Such supplementation has indicated anti-inflammatory and antioxidant properties in farmed fish. In this study, dietary supplementation of zinc, selenium, ascorbic acid and niacin, at levels 2 to 3-fold higher than recommended, was evaluated as a measure to promote skin health and antioxidant defense in European seabass, Dicentrarchus labrax, fry. For this purpose, fish survival, growth performance, fin and skin erosions as well as whole-fish antioxidant enzyme activity (catalase, selenium (Se)-independent and dependent glutathione peroxidase) were assessed. Moreover, bacterial load in the rearing water and skin mucus were evaluated to assess the potential of the dietary micronutrient mixture as a preventive from natural infections. A group fed with a diet including these micronutrients at recommended levels served as a control. Surplus of these micronutrients significantly reduced the percentage of fish with eroded fins, while also induced the activity of catalase and Se-dependent glutathione peroxidase. Fish growth and bacterial loads in the water and fish skin mucus were not affected, whereas no skin lesions were observed. Overall, a mineral- and vitamin-supplemented diet at levels higher than recommended seems to act as a promotor of skin health and prevent from fin erosions, potentially through an increase in the antioxidant defense system.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_native_2020,

title = {Native parasite affecting an introduced host in aquaculture: cardiac henneguyosis in the red seabream Pagrus major Temminck & Schlegel (Perciformes: Sparidae) caused by Henneguya aegea n. sp. (Myxosporea: Myxobolidae)},

author = {Pantelis Katharios and Panos Varvarigos and Kleoniki Keklikoglou and Maja Ruetten and Jerry Sojan and Morgina Akter and Maria Chiara Cascarano and Maria Ioanna Tsertou and Constantina Kokkari},

url = {https://doi.org/10.1186/s13071-020-3888-7},

doi = {10.1186/s13071-020-3888-7},

issn = {17563305},

year  = {2020},

date = {2020-01-01},

journal = {Parasites & Vectors},

volume = {13},

number = {1},

pages = {27},

abstract = {BACKGROUND: Henneguya Thélohan, 1892 (Myxobolidae) is one of the most species-rich genera of myxosporean parasites infecting fish. Although common in nature, there are few reports of these parasites causing important disease in aquaculture. In this paper, we describe a new species of Henneguya infecting Pagrus major (Temminck & Schlegel), a fish host introduced to the Mediterranean Sea from Japan in the late 1980s. RESULTS: Large plasmodia of the parasite were found in the bulbus arteriosus and in the ventricle of the infected fish. Spores were found mainly in the kidney and heart and were accompanied by melanized macrophages or vascular intimal proliferation mixed with a mild non-suppurative response, respectively. Comparisons of morphometric data for spore and polar capsule length and width, suggest a unique combination of features in the newly described species. Molecular analysis, based on 18S rDNA sequence of the parasite, followed by phylogenetic analysis, indicated that the parasite described here is a novel species of Henneguya, clustered with the marine congeneric species. CONCLUSIONS: Henneguya aegea n. sp. infects in aquaculture P. major, a host introduced as eggs to the Mediterranean from Japan. Despite the high host specificity of the myxobolid parasites, H. aegea n. sp. seems to be able to use P. major as a host and propagate successfully, causing morbidity and mortality. This could result in spillback of the new species from high density cultured non-native P. major to native fish hosts.},

note = {ISBN: 1307102038887 

Publisher: BioMed Central},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{misol_biological_2020,

title = {Biological and Genomic Characterization of a Novel Jumbo Bacteriophage, vB_VhaM_pir03 with Broad Host Lytic Activity against Vibrio harveyi},

author = {Gerald N Misol and Constantina Kokkari and Pantelis Katharios},

url = {https://www.mdpi.com/2076-0817/9/12/1051

https://imbbc.hcmr.gr/wp-content/uploads/2020/12/2020-Misol-Pathogens-53.pdf},

doi = {10.3390/pathogens9121051},

issn = {2076-0817},

year  = {2020},

date = {2020-01-01},

urldate = {2020-12-29},

journal = {Pathogens},

volume = {9},

number = {12},

pages = {1051},

abstract = {Vibrio harveyi is a Gram-negative marine bacterium that causes major disease outbreaks and economic losses in aquaculture. Phage therapy has been considered as a potential alternative to antibiotics however, candidate bacteriophages require comprehensive characterization for a safe and practical phage therapy. In this work, a lytic novel jumbo bacteriophage, vB_VhaM_pir03 belonging to the Myoviridae family was isolated and characterized against V. harveyi type strain DSM19623. It had broad host lytic activity against 31 antibiotic-resistant strains of V. harveyi, V. alginolyticus, V. campbellii and V. owensii. Adsorption time of vB_VhaM_pir03 was determined at 6 min while the latent-phase was at 40 min and burst-size at 75 pfu/mL. vB_VhaM_pir03 was able to lyse several host strains at multiplicity-of-infections (MOI) 0.1 to 10. The genome of vB_VhaM_pir03 consists of 286,284 base pairs with 334 predicted open reading frames (ORFs). No virulence, antibiotic resistance, integrase encoding genes and transducing potential were detected. Phylogenetic and phylogenomic analysis showed that vB_VhaM_pir03 is a novel bacteriophage displaying the highest similarity to another jumbo phage, vB_BONAISHI infecting Vibrio coralliilyticus. Experimental phage therapy trial using brine shrimp, Artemia salina infected with V. harveyi demonstrated that vB_VhaM_pir03 was able to significantly reduce mortality 24 h post infection when administered at MOI 0.1 which suggests that it can be an excellent candidate for phage therapy.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{leon_diversification_2019,

title = {Diversification of vibrio anguillarum driven by the bacteriophage CHOED},

author = {Marcela León and Constantina Kokkari and Katherine García and Daniel Castillo and Pantelis Katharios and Roberto Bastías},

doi = {10.3389/fmicb.2019.01396},

issn = {1664302X},

year  = {2019},

date = {2019-01-01},

journal = {Frontiers in Microbiology},

volume = {10},

pages = {1396},

abstract = {Bacteriophages are an important factor in bacterial evolution. Some reports suggest that lytic bacteriophages can select for resistant mutant strains with reduced virulence. The present study explores the role of the CHOED bacteriophage in the diversification and virulence of its host Vibrio anguillarum. Nine phage-resistant strains were analyzed for their phenotype and different virulence factors, showing alterations in their fitness, motility, biofilm formation, lipopolysaccharide profiles and/or protease activity. Seven of the nine phage-resistant strains showed virulence reduction in a Sparus aurata larvae model. However, this is not generalized since two of the resistant strains show equal virulence compared with the parental strain. The genomic analysis of representative resistant strains displayed that the majority of the mutations are specific for each isolate, affecting genes related to lipopolysaccharide biosynthesis, quorum sensing, motility, toxin and membrane transport. The observed mutations were coherent with the phenotypic and virulence differences observed. These results suggest that the CHOED phage acts as a selective pressure on V. anguillarum, allowing proliferation of resistant strains with different genotypes, phenotypes and degrees of virulence, contributing to bacterial diversification.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_characterization_2019,

title = {Characterization of a highly virulent Edwardsiella anguillarum strain isolated from Greek aquaculture, and a spontaneously induced prophage therein},

author = {Pantelis Katharios and Panos G Kalatzis and Constantina Kokkari and Michail Pavlidis and Qiyao Wang},

doi = {10.3389/fmicb.2019.00141},

issn = {1664302X},

year  = {2019},

date = {2019-01-01},

journal = {Frontiers in Microbiology},

volume = {10},

pages = {141},

abstract = {Edwardsiella-associated outbreaks are increasingly reported on both marine and freshwater aquaculture setups, accounting for severe financial and biomass losses. E. tarda, E. ictaluri, and E. hoshinae have been the traditional causative agents of edwardsiellosis in aquaculture, however, intensive studies due to the significance of the disease have just recently revealed two more species, E. piscicida and E. anguillarum. Whole genome sequencing that was conducted on the strain EA011113, isolated from farmed Diplodus puntazzo after an edwardsiellosis outbreak in Greece, confirmed it as a new clinical strain of E. anguillarum. Extensive phylogenetic analysis showed that this Greek strain is closely related to an Israeli E. piscicida-like clinical strain, isolated from diseased groupers, Epinephelus aeneus and E. marginatus in Red Sea. Bioinformatic analyses of E. anguillarum strain EA011113 unveiled a wide repertoire of potential virulence factors, the effect of which was corroborated by the mortalities that the strain induced in adult zebrafish, Danio rerio, under different levels of infection intensity (LD50 after 48 h: 1.85 × 104 cfu/fish). This strain was non-motile and according to electron microscopy lacked flagella, a fact that is not typical for E. anguillarum. Comparative genomic analysis revealed a deletion of 36 nt found in the flagellar biosynthetic gene (FlhB) that could explain that trait. Further in silico analysis revealed an intact prophage that was integrated in the bacterial genome. Following spontaneous induction, the phage was isolated, purified, characterized and independently sequenced, confirming its viability as a free, inducible virion as well. Separate genomic analysis of the prophage implies a plausible case of lysogenic conversion. Focusing on edwardsiellosis as a rapidly emerging aquaculture disease on a global scale, this work offers some insight into the virulence, fitness, and potential lysogenic conversion of a of a newly described, yet highly pathogenic, strain of E. anguillarum.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kokkari_isolation_2018,

title = {Isolation and characterization of a novel bacteriophage infecting Vibrio alginolyticus},

author = {C Kokkari and E Sarropoulou and R Bastias and M Mandalakis and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040930909&doi=10.1007%2fs00203-018-1480-8&partnerID=40&md5=b22268a55a9ed98e93e66d4448fbe221},

doi = {10.1007/s00203-018-1480-8},

issn = {03028933},

year  = {2018},

date = {2018-01-01},

journal = {Archives of Microbiology},

volume = {200},

number = {5},

pages = {707--718},

abstract = {Vibrio alginolyticus is a common marine bacterium implicated in disease outbreaks in marine farmed fish and invertebrates. Due to the inappropriate use of antibiotics in aquaculture, alternative therapies have been proposed. One of the most promising options is the use of lytic bacteriophages to control pathogenic bacteria. This work describes the isolation and characterization of a lytic phage (VEN) against a V. alginolyticus strain (V2) isolated from a disease outbreak in common dentex (Dentex dentex) cultured at the Hellenic Centre for Marine Research (HCMR) in Crete, Greece. The bacteriophage is morphologically similar to phages from Podoviridae family and remained stable for 1 year at 4 °C and over 1 h when kept at 50 °C. VEN was able to lyse the host bacteria at several multiplicity of infection (MOI) (0.1–100) in liquid cultures. However, it was unable to infect other V. alginolyticus strains. Its genome consists of 44,603 bp with a GC content of 43.5%, while sequence analysis revealed the presence of 54 potential ORFs with a T7-like genomic organization. Almost 65% of the predicted ORFs presented homology with proteins of the vibriophages Vc1 and phi-A318 infecting Vibrio cyclitrophicus and Vibrio alginolyticus, respectively. Phylogenetic analysis applying the amino acid sequence of the large terminase subunit confirmed the close relationship of these phages. Furthermore, the comparison of the RNA polymerase of these phages revealed that the motifs A, B and C related to the catalytic activity and the recognition loop related to promotor identification were also conserved. VEN has an obligate lytic life cycle demonstrated by experimental data and genomic analysis. These results suggest that VEN may provide a good candidate to control recurrent diseases caused by V. alginolyticus at HCMR. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.},

note = {Publisher: Springer Verlag},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{tsertou_aetiology_2018,

title = {The aetiology of systemic granulomatosis in meagre (Argyrosomus regius): The “Nocardia” hypothesis},

author = {M I Tsertou and M Smyrli and C Kokkari and E Antonopoulou and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85052467668&doi=10.1016%2fj.aqrep.2018.08.002&partnerID=40&md5=625a13223330d31956144851287ee794},

doi = {10.1016/j.aqrep.2018.08.002},

issn = {23525134},

year  = {2018},

date = {2018-01-01},

journal = {Aquaculture Reports},

volume = {12},

pages = {5--11},

abstract = {One of the most important bottlenecks of meagre (Argyrosomus regius) production is Systemic Granulomatosis (SG), a pathological condition affecting the majority of farmed populations. The aetiology of the disease, which is characterized by multiple granulomas in all soft tissues, is unknown; however, two hypotheses have been raised. The first is that it may be a metabolic disorder similar to systemic granulomas observed in other cultured fishes. The second hypothesis is that it is caused by bacterial pathogens, most likely Nocardia spp. (i.e. nocardiosis). The aim of this study was to test the bacterial pathogen hypothesis as the aetiological factor of SG. Meagre from various locations of Greece were sampled and examined using microbiological, molecular and histological techniques. The prevalence of granulomas in fish was 100% and was not correlated to an infectious agent, whereas nocardiosis was found in a single incidence (prevalence: 1.3%). The results suggest that nocardiosis is not the cause of SG, as it is most probably present in a confined geographical region in Greece. The metabolic disorder hypothesis for SG is more probable and more research has to been done to conclusively identify the aetiological factor of SG. © 2018 The Authors},

note = {Publisher: Elsevier B.V.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kalatzis_stumbling_2017,

title = {Stumbling across the same phage: Comparative genomics of widespread temperate phages infecting the fish pathogen Vibrio anguillarum},

author = {P G Kalatzis and N Rørbo and D Castillo and J J Mauritzen and J Jørgensen and C Kokkari and F Zhang and P Katharios and M Middelboe},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019581810&doi=10.3390%2fv9050122&partnerID=40&md5=a0f1b080ff39b0a1d1bc21f1692e1b58},

doi = {10.3390/v9050122},

issn = {19994915},

year  = {2017},

date = {2017-01-01},

journal = {Viruses},

volume = {9},

number = {5},

pages = {122},

abstract = {Nineteen Vibrio anguillarum-specific temperate bacteriophages isolated across Europe and Chile from aquaculture and environmental sites were genome sequenced and analyzed for host range, morphology and life cycle characteristics. The phages were classified as Siphoviridae with genome sizes between 46,006 and 54,201 bp. All 19 phages showed high genetic similarity, and 13 phages were genetically identical. Apart from sporadically distributed single nucleotide polymorphisms (SNPs), genetic diversifications were located in three variable regions (VR1, VR2 and VR3) in six of the phage genomes. Identification of specific genes, such as N6-adenine methyltransferase and lambda like repressor, as well as the presence of a tRNAArg, suggested a both mutualistic and parasitic interaction between phages and hosts. During short term phage exposure experiments, 28% of a V. anguillarum host population was lysogenized by the temperate phages and a genomic analysis of a collection of 31 virulent V. anguillarum showed that the isolated phages were present as prophages in textgreater50% of the strains covering large geographical distances. Further, phage sequences were widely distributed among CRISPR-Cas arrays of publicly available sequenced Vibrios. The observed distribution of these specific temperate Vibriophages across large geographical scales may be explained by efficient dispersal of phages and bacteria in the marine environment combined with a mutualistic interaction between temperate phages and their hosts which selects for co-existence rather than arms race dynamics. © 2017 by the authors. Licensee MDPI, Basel, Switzerland.},

note = {Publisher: MDPI AG},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_isolation_2017,

title = {Isolation and characterization of a N4-like lytic bacteriophage infecting Vibrio splendidus, a pathogen of fish and bivalves},

author = {P Katharios and P G Kalatzis and C Kokkari and E Sarropoulou and M Middelboe},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039803769&doi=10.1371%2fjournal.pone.0190083&partnerID=40&md5=764cc6c742f2f2111527fd680e4aa5b2},

doi = {10.1371/journal.pone.0190083},

issn = {19326203},

year  = {2017},

date = {2017-01-01},

journal = {PLoS ONE},

volume = {12},

number = {12},

pages = {e0190083},

abstract = {A novel virulent bacteriophage, vB_VspP_pVa5, infecting a strain of Vibrio splendidus was isolated from a sea-cage aquaculture farm in Greece, and characterized using microbiological methods and genomic analysis. Bacteriophage vB_VspP_pVa5 is a N4-like podovirus with an icosahedral head measuring 85 nm in length and a short non-contractile tail. The phage had a narrow host range infecting only the bacterial host, a latent period of 30 min and a burst size of 24 virions per infected bacterium. Its genome size was 78,145 bp and genomic analysis identified 107 densely-packed genes, 40 of which could be annotated. In addition to the very large virion encapsulated DNA-dependent RNA polymerase which is the signature of the N4-like genus, an interesting feature of the novel phage is the presence of a self-splicing group I intron in the thymidylate synthase gene. A tRNAStop interrupted by a 2.5kb open reading frame–containing area was also identified. The absence of genes related to lysogeny along with the high efficacy observed during in vitro cell lysis trials, indicate that the vB_VspP_pVa5 is a potential candidate component in a bacteriophage cocktail suitable for the biological control of V. splendidus in aquaculture. © 2017 Katharios et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.},

note = {Publisher: Public Library of Science},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{smyrli_aeromonas_2017,

title = {Aeromonas veronii infection associated with high morbidity and mortality in farmed European seabass Dicentrarchus labrax in the Aegean Sea, Greece},

author = {M Smyrli and A Prapas and G Rigos and C Kokkari and M Pavlidis and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022184875&doi=10.3147%2fjsfp.52.68&partnerID=40&md5=d4e9a7e3342b0d17ae8291af235a0206},

doi = {10.3147/jsfp.52.68},

issn = {0388788X},

year  = {2017},

date = {2017-01-01},

journal = {Fish Pathology},

volume = {52},

number = {2},

pages = {68--81},

abstract = {In the present study, we examined a disease caused by Aeromonas veronii bv. sobria in sea cage-farmed European seabass Dicentrarchus labrax, in the Aegean Sea, Greece. Commercial sized fish were affected by A. veronii bv. sobria and exhibited high morbidity and mortality. Gross pathologic features and histology revealed a systemic infection characterized by the presence of abscesses and chronic granulomatous inflammation. Two clinical bacterial isolates (Aero NS and Aero PDB) were identified as A. veronii bv. sobria based on bacteriological characteristics and sequence analysis for 16S rRNA and gyrB genes. Infectivity tests in the form of intraperitoneal injection administration (Aero NS) and immersion in a bacterial suspension (Aero NS and Aero PDB) revealed that both isolates could cause clinical signs similar to those observed in the field and high mortality rate. To our knowledge, this is the first report of A. veronii bv. sobria isolated from farmed European seabass in the Mediterranean Sea accompanied by supporting data of its pathogenicity. © 2017 The Japanese Society of Fish Pathology.},

note = {Publisher: Japanese Society of Fish Pathology},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kalatzis_isolation_2016,

title = {Isolation and characterization of two lytic bacteriophages, φst2 and φgrn1; Phage therapy application for biological control of vibrio alginolyticus in aquaculture live feeds},

author = {P G Kalatzis and R Bastías and C Kokkari and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961152351&doi=10.1371%2fjournal.pone.0151101&partnerID=40&md5=3cd378d8fe59cedc364f9f85f58851ef},

doi = {10.1371/journal.pone.0151101},

issn = {19326203},

year  = {2016},

date = {2016-01-01},

journal = {PLoS ONE},

volume = {11},

number = {3},

abstract = {Bacterial infections are a serious problem in aquaculture since they can result in massive mortalities in farmed fish and invertebrates. Vibriosis is one of the most common diseases in marine aquaculture hatcheries and its causative agents are bacteria of the genus Vibrio mostly entering larval rearing water through live feeds, such as Artemia and rotifers. The pathogenic Vibrio alginolyticus strain V1, isolated during a vibriosis outbreak in cultured seabream, Sparus aurata, was used as host to isolate and characterize the two novel bacteriophages φSt2 and φGrn1 for phage therapy application. In vitro cell lysis experiments were performed against the bacterial host V. alginolyticus strain V1 but also against 12 presumptive Vibrio strains originating from live prey Artemia salina cultures indicating the strong lytic efficacy of the 2 phages. In vivo administration of the phage cocktail, φSt2 and φGrn1, at MOI = 100 directly on live prey A. salina cultures, led to a 93% decrease of presumptive Vibrio population after 4 h of treatment. Current study suggests that administration of φSt2 and φGrn1 to live preys could selectively reduce Vibrio load in fish hatcheries. Innovative and environmental friendly solutions against bacterial diseases are more than necessary and phage therapy is one of them. © 2016 Kalatzis et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.},

note = {Publisher: Public Library of Science},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{castillo_draft_2015,

title = {Draft genome sequences of the fish pathogen Vibrio harveyi strains VH2 and VH5},

author = {D Castillo and P D'Alvise and M Middelboe and L Gram and S Liu and P G Kalatzis and C Kokkari and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008929958&doi=10.1128%2fgenomeA.01062-15&partnerID=40&md5=2dfb9decf27ca3d6752ac7331683d3f3},

doi = {10.1128/genomeA.01062-15},

issn = {21698287},

year  = {2015},

date = {2015-01-01},

journal = {Genome Announcements},

volume = {3},

number = {5},

pages = {e01062--15},

abstract = {Vibrio harveyi is an important marine pathogen that is responsible for vibriosis outbreaks in cultured fish and invertebrates worldwide. Here, we announce the draft genome sequences of V. harveyi strains VH2 and VH5, isolated from farmed juvenile Seriola dumerili during outbreaks of vibriosis in Crete, Greece. © 2015 Castillo et al.},

note = {Publisher: American Society for Microbiology},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kalatzis_morphological_2015,

title = {Morphological characterisation and phylogenetic relationships of Zschokkella candia n. sp. from the gall-bladder of Sparisoma cretense (L.) (Perciformes: Scaridae) in the Sea of Crete off Greece},

author = {P G Kalatzis and C Kokkari and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943234121&doi=10.1007%2fs11230-015-9594-8&partnerID=40&md5=e43e7892cbdaf98c88dcb5f221b2f54f},

doi = {10.1007/s11230-015-9594-8},

issn = {01655752},

year  = {2015},

date = {2015-01-01},

journal = {Systematic Parasitology},

volume = {92},

number = {3},

pages = {211--218},

abstract = {A new myxosporean parasite, Zschokkella candia n. sp., from the gall-bladder of the wild parrotfish Sparisoma cretense (L.) (Perciformes: Scaridae) is described based on light and scanning electron microscopy. Mature spores are elliptical, with mean dimensions 11.2 ± 0.5 × 7.8 ± 0.1 μm and possess spherical polar capsules with mean diameter of 2.3 ± 0.3 μm. The new species is differentiated from other similar species of the genus based on spore morphology, its coelozoic life-style and molecular data. The phylogenetic tree constructed using maximum likelihood analysis of small subunit (SSU) rDNA sequence data complements the characterisation of Zschokkella candia n. sp. by defining its phylogenetic position among the species of Zschokkella Auerbach, 1909 sequenced to date. The phylogenetic analysis supports the existing knowledge on the complicated polyphyletic relationships among the members of the genus Zschokkella. © 2015, Springer Science+Business Media Dordrecht.},

note = {Publisher: Kluwer Academic Publishers},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{castillo_draft_2015-1,

title = {Draft genome sequences of Vibrio alginolyticus strains V1 and V2, opportunistic marine pathogens},

author = {D Castillo and P D'Alvise and P G Kalatzis and C Kokkari and M Middelboe and L Gram and S Liu and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008429014&doi=10.1128%2fgenomeA.00729-15&partnerID=40&md5=52c4090ca04c4acf8107d2bbde043ddc},

doi = {10.1128/genomeA.00729-15},

issn = {21698287},

year  = {2015},

date = {2015-01-01},

journal = {Genome Announcements},

volume = {3},

number = {4},

pages = {e00729--15},

abstract = {We announce the draft genome sequences of Vibrio alginolyticus strains V1 and V2, isolated from juvenile Sparus aurata and Dentex dentex, respectively, during outbreaks of vibriosis. The genome sequences are 5,257,950 bp with a G+C content of 44.5% for V. alginolyticus V1 and 5,068,299 bp with a G+C content of 44.8% for strain V2. These genomes provide further insights into the putative virulence factors, prophage carriage, and evolution of this opportunistic marine pathogen. © 2015 Castillo et al.},

note = {Publisher: American Society for Microbiology},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_first_2015,

title = {First report of Edwardsiellosis in cage-cultured sharpsnout sea bream, Diplodus puntazzo from the Mediterranean},

author = {P Katharios and C Kokkari and N Dourala and M Smyrli},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84937551746&doi=10.1186%2fs12917-015-0482-x&partnerID=40&md5=a7c848edbc8a8ac0151f14734aabb8cf},

doi = {10.1186/s12917-015-0482-x},

issn = {17466148},

year  = {2015},

date = {2015-01-01},

journal = {BMC Veterinary Research},

volume = {11},

number = {1},

pages = {155},

abstract = {Background: Edwardsiella tarda, is a serious bacterial pathogen affecting a broad range of aquaculture fish species. The bacterium has also been reported as a human pathogen, however recent studies have dissociated the fish pathogenic Edwardsiella from those isolated from humans by placing them in a new species, E. piscicida. Here we report the first case of Edwardsiellosis in cultured sharpsnout sea breams, Diplodus puntazzo in Greece. Case presentation: The disease has affected cultured sharpsnout sea breams of a commercial fish farm in a single location in East Greece. Two populations of sharpsnout sea breams stocked in two consecutive years in floating cages presented signs of disease which included nodules and abscesses in spleen and kidney, morbidity and cumulative mortality reaching 5.3 %. Using microbiological, biochemical and molecular tools we have identified Edwardsiella sp. as the main aetiological factor of the disease. Following phylogenetic analysis the bacterial isolates are grouped with the newly described Edwardsiella piscicida species. Conclusions: This is the first report of Edwardsiellosis in this species but most importantly in sea cage-cultured fish in the Mediterranean which may pose a serious threat for aquaculture fish species in this region. © 2015 Katharios et al.},

note = {Publisher: BioMed Central Ltd.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{katharios_enteromyxum_2014,

title = {Enteromyxum leei infection in parrotfish, Sparisoma cretense: Histopathological, morphological and molecular study},

author = {P Katharios and C Kokkari and A Sterioti and M Smyrli and P G Kalatzis},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84890553160&doi=10.1016%2fj.vetpar.2013.10.011&partnerID=40&md5=f9944a453e454ecfa3c4431daeb37632},

doi = {10.1016/j.vetpar.2013.10.011},

issn = {03044017},

year  = {2014},

date = {2014-01-01},

journal = {Veterinary Parasitology},

volume = {199},

number = {3-4},

pages = {136--143},

abstract = {Enteromyxum leei (Myxozoa) has been identified as the aetiological agent of morbidity and mortality in captive feral parrotfish, Sparisoma cretense held at the facilities of Cretaquarium, the public aquarium of the Hellenic Centre for Marine Research in Crete. The parasite caused substantial mortality to the parrotfish exceeding 60% over a period of 3.5 months. Here we describe the course of disease, the effects of the parasite on the host based on histopathological observations and we provide morphological and molecular data on the parasite. © 2013 Elsevier B.V.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kalatzis_description_2013,

title = {Description and relationships of two novel species of Ceratomyxa Thelohan, 1892 infecting the gallbladders of Aulopiformes: Atlantic lizardfish Synodus saurus Linnaeus, 1758 and royal flagfin Aulopus filamentosus Bloch, 1792 from Cretan Sea, Greece},

author = {P G Kalatzis and C Kokkari and P Katharios},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84876289084&doi=10.1007%2fs00436-013-3366-7&partnerID=40&md5=a06d035fd72a62aa863bce67aeed3dbb},

doi = {10.1007/s00436-013-3366-7},

issn = {09320113},

year  = {2013},

date = {2013-01-01},

journal = {Parasitology Research},

volume = {112},

number = {5},

pages = {2055--2061},

abstract = {Two members of Aulopiformes (grinners) were examined for myxosporean parasites in their gallbladders. Synodus saurus and Aulopus filamentosus from Cretan Sea, Greece were infected by Ceratomyxa parasites which are described in this paper. Both species of Ceratomyxa are new and referred for the first time as Ceratomyxa cretensis n.sp. and Ceratomyxa filamentosi n.sp. The new species are described morphologically by light and scanning electron microscopy analysis, and characterized genetically by sequencing the small subunit (SSU) rDNA. The SSU rDNA sequences obtained from the two novel Ceratomyxa species were used for the construction of a phylogenetic tree with all the available Ceratomyxa SSU rDNA sequences. © 2013 Springer-Verlag Berlin Heidelberg.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{koumoundouros_temperature_2002,

title = {Temperature sex determination in the European sea bass, Dicentrarchus labrax (L., 1758) (Teleostei, Perciformes, Moronidae): Critical sensitive ontogenetic phase},

author = {George Koumoundouros and Michalis Pavlidis and Lina Anezaki and Constantina Kokkari and Aspasia Sterioti and Pascal Divanach and Maroudio Kentouri},

url = {http://doi.wiley.com/10.1002/jez.10095},

doi = {10.1002/jez.10095},

issn = {0022-104X, 1097-010X},

year  = {2002},

date = {2002-05-01},

urldate = {2020-08-18},

journal = {Journal of Experimental Zoology},

volume = {292},

number = {6},

pages = {573--579},

abstract = {The temperature sex determination (TSD) mechanism in the European sea bass (Dicentrarchus labrax L.) was studied in respect to: a) the TSD sensitivity during the different developmental stages; and b) the intrapopulation correlation of sex determination with the growth rate up to the end of the TSD-sensitive period. At the stage of half-epiboly, eggs from the same batch were divided into four groups and subjected to different thermal treatments: a) 15°C (G15 group) and b) 20°C (G20 group) up to the middle of metamorphosis stage; c) 15°C up to the end of yolk-sac larval stage and subsequently to 20°C (G15-5 group); and d) 15°C up to the end of the preflexion stage and then to 20°C (G15-10 group). At the end of the treatments, size grading was applied and four additional populations were established from the upper (L) and lower (S) size portions of the G15 and G20 populations: G15L, G15S, G20L, and G20S. During the following growing phase, all populations were subjected to common rearing conditions. The sex ratios of each population were macroscopically determined at 190-210 mm mean total length. Female incidence was significantly affected (P textless 0.05) by the different thermal treatments: 66.1% in the G15, 47.1% in the G15-10, 37.6% in the G15-5, and 18.1% in the G20 group. In addition, sex ratio was correlated with the growth rate of the fish up to the end of the TSD-sensitive period, with the larger fish presenting a significantly higher (P textless 0.01) female incidence than the smaller fish in both thermal regimes tested: 73.1% in G15L vs. 57% in G15S, and 36.6%in G20L vs. 22.5% in G20S group. Results provide, for the first time, clear evidence that the sea bass is sensitive to TSD during all different ontogenetic stages up to metamorphosis, and that sex ratio is correlated with the growth rate of the fish well before the differentiation and maturation of the gonads. © 2002 Wiley-Liss, Inc.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pavlidis_seasonal_2000,

title = {Seasonal variations and maturity stages in relation to differences in serum levels of gonadal steroids, vitellogenin, and thyroid hormones in the common dentex (Dentex dentex)},

author = {M Pavlidis and L Greenwood and B Mourot and C Kokkari and F Le Menn and P Divanach and A P Scott},

url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034006188&partnerID=40&md5=d5286b0db60ae52af7841e4963700b70},

year  = {2000},

date = {2000-01-01},

journal = {General and Comparative Endocrinology},

volume = {118},

pages = {14 -- 25},

abstract = {Seasonal variations in serum concentrations of 17β-estradiol (E2), vitellogenin (Vg), testosterone (T), 11 ketotestosterone (11-KT), and thyroid hormones (T4, L-thyroxine; and T3, 3,5,3’-triiodo-L-thyronine) were investigated during the first, second, and third reproductive cycles in intensively reared populations of common dentex, Dentex dentex, and correlated with gonadal development and spawning. In females, there were baseline E2 values (<0.10 ng/ml) and negligible Vg concentrations during the postspawning and pregametogenesis period (June to December), and these increased thereafter to peak during the spawning period. Maximum T3 and T4 serum concentrations were found around spawning. There was a positive correlation during vitellogenesis and final maturation between Vg and T3 (r2 = 0.366). In addition, Vg and T3 concentrations were statistically higher in the stages of vitellogenesis and final maturation than at the other stages (P < 0.001). Minimum T3 and T4 concentrations (October) coincided with the decrease in water temperature and the associated decrease in the daily feeding rate and the specific growth rate. In males, as in females, seasonal changes in serum levels of T and 11-KT were well correlated with gonadal development. The presence of males in the stage of completed spermiogenesis in December coincided with the surge in both androgens and this increase lasted until the end of the spawning period. There were no significant differences in serum T3 and T4 levels among the maturity stages. The observed seasonal changes in serum gonadal steroids and Vg reflected the pattern of oocyte development and the spawning behavior of common dentex and were typical of the patterns described in most multiple spawners studied to date. Thyroid hormones may enhance early ovarian development and stimulate vitellogenesis in female dentex. (C) 2000 Academic Press.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{pavlidis_prothrombin_1999,

title = {Prothrombin time, activated partial thromboplastin time and fibrinogen values in Mediterranean marine teleosts},

author = {M Pavlidis and M Berry and C Kokkari and M Kentouri},

url = {http://link.springer.com/10.1023/A:1007882020754},

doi = {10.1023/A:1007882020754},

issn = {09201742},

year  = {1999},

date = {1999-01-01},

urldate = {2020-08-18},

journal = {Fish Physiology and Biochemistry},

volume = {21},

number = {4},

pages = {335--343},

abstract = {Coagulation profiles for marine fish were determined with the standard global screening assays, the prothrombin time (PT) and activated partial thromboplastin time (APTT) using homologous tissue thromboplastin and phospholipid extracts to investigate species-specificity of brain thromboplastins, and to establish a base-line coagulation profile for marine fish of economical importance for Mediterranean aquaculture (sea bream, Sparus aurata, sea bass, Dicentrarchus labrax, red porgy, Pagrus pagrus, common dentex, Dentex dentex). Sea bass and sea bream displayed the shortest PT (9.0-15.0 s) and APTT (22.1-35.8 s) in comparison to the other species (PT: 24.8-37.2 s, APTT: 39.6-66.4 s). Red porgy displayed the lowest fibrinogen value (1.2-2.3 g 1 -1), while no differences were found among the other species (2.2-2.8 g 1 -1). It is concluded that the interaction of the tissue factor and plasma clotting factor is relatively species specific and that the use of homologous brain extracts is preferable for haemostasis study in marine fish.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}