George Tsiamis | University of Patras (original) (raw)

Papers by George Tsiamis

Development and implementation of safe natural alternatives to synthetic pesticides are urgent ne... more Development and implementation of safe natural alternatives to synthetic pesticides are urgent needs that will provide ecological solutions for control of plant diseases, bacteria, viruses, nematodes, pests, and weeds, to ensure economic stability of the farmers and food security as well as protection of the environment and human health. Unambiguously, production of botanical pesticides will allow sustainable and efficient use of natural resources and finally decrease the use of chemical inputs and burden. This is underlined by the strict regulations on pesticide residues in agricultural products and harmonized with the Farm to Fork strategy aimed to reduce pesticide use by 55%, by 2030. Recognizing the urgent need for natural pesticides development, this work is an overview of the current research on the valorization of Mediterranean plants as potential source of biopesticides. More specifically, the extraction methods, the chemical composition, the biopesticidal activity, the comm...

BioMed Research International, 2013

Human life and activity depends on microorganisms, as they are responsible for providing basic el... more Human life and activity depends on microorganisms, as they are responsible for providing basic elements of life. Although microbes have such a key role in sustaining basic functions for all living organisms, very little is known about their biology since only a small fraction (average 1%) can be cultured under laboratory conditions. This is even more evident when considering that >88% of all bacterial isolates belong to four bacterial phyla, theProteobacteria,Firmicutes,Actinobacteria, andBacteroidetes. Advanced technologies, developed in the last years, promise to revolutionise the way that we characterize, identify, and study microbial communities. In this review, we present the most advanced tools that microbial ecologists can use for the study of microbial communities. Innovative microbial ecological DNA microarrays such as PhyloChip and GeoChip that have been developed for investigating the composition and function of microbial communities are presented, along with an overvi...

Frontiers in Microbiology

Laboratory adaptation process used in sterile insect technique (SIT) programs can exert a signifi... more Laboratory adaptation process used in sterile insect technique (SIT) programs can exert a significant impact on the insect-gut microbiome relationship, which may negatively impact the quality and performance of the fly. In the present study, changes in the gut microbiota that occur through laboratory adaptation of two Ceratitis capitata populations were investigated: Vienna 8 genetic sexing strain (GSS), a long-established control line, and a wild population recently introduced to laboratory conditions. The bacterial profiles were studied for both strains using amplicon sequencing of the 16S rRNA V3-V4 hypervariable region in larvae and in the gastrointestinal tract of teneral (1 day) and adults (5 and 15 days) reared under laboratory conditions for 14 generations (F0–F13). Findings demonstrated the development of distinct bacterial communities across the generations with differences in the bacterial composition, suggesting a strong impact of laboratory adaptation on the fly bacteri...

Biomolecules, 2022

Concerning human and environmental health, safe alternatives to synthetic pesticides are urgently... more Concerning human and environmental health, safe alternatives to synthetic pesticides are urgently needed. Many of the currently used synthetic pesticides are not authorized for application in organic agriculture. In addition, the developed resistances of various pests against classical pesticides necessitate the urgent demand for efficient and safe products with novel modes of action. Botanical pesticides are assumed to be effective against various crop pests, and they are easily biodegradable and available in high quantities and at a reasonable cost. Many of them may act by diverse yet unexplored mechanisms of action. It is therefore surprising that only few plant species have been developed for commercial usage as biopesticides. This article reviews the status of botanical pesticides, especially in Europe and Mediterranean countries, deepening their active principles and mechanisms of action. Moreover, some constraints and challenges in the development of novel biopesticides are h...

Additional file 1. Supplementary materials.

Journal of Food Processing and Preservation, 2019

Oromiehie, 2018). The main reason for this fact was because such materials could disperse into na... more Oromiehie, 2018). The main reason for this fact was because such materials could disperse into nanoscale and exhibit improved antimicrobial, mechanical, and barrier properties. Following the global trend to use biomass and by-products in the production chain, more and more industries plan to use chitosan (CS) as a biopolymer for their processes. Moreover, a continuously increasing effort is given to the replacement of the chemical preservatives with organic antioxidants such as extracted oils from plants. The main target of this work was the development of an advanced active packaging film for food conservation based on the use of three materials with complementary interaction. The first material was CS, a food by-product. CS is the second most abundant natural polysaccharide after cellulose (Muzzarelli et

Genome Biology, 2019

Background: Tsetse flies (Glossina sp.) are the vectors of human and animal trypanosomiasis throu... more Background: Tsetse flies (Glossina sp.) are the vectors of human and animal trypanosomiasis throughout sub-Saharan Africa. Tsetse flies are distinguished from other Diptera by unique adaptations, including lactation and the birthing of live young (obligate viviparity), a vertebrate blood-specific diet by both sexes, and obligate bacterial symbiosis. This work describes the comparative analysis of six Glossina genomes representing three sub-genera: Morsitans (G. morsitans morsitans, G. pallidipes, G. austeni), Palpalis (G. palpalis, G. fuscipes), and Fusca (G. brevipalpis) which represent different habitats, host preferences, and vectorial capacity. Results: Genomic analyses validate established evolutionary relationships and sub-genera. Syntenic analysis of Glossina relative to Drosophila melanogaster shows reduced structural conservation across the sex-linked X chromosome. Sex-linked scaffolds show increased rates of female-specific gene expression and lower evolutionary rates relative to autosome associated genes. Tsetse-specific genes are enriched in protease, odorant-binding, and helicase activities. Lactation-associated genes are conserved across all Glossina species while male seminal proteins are rapidly evolving. Olfactory and gustatory genes are reduced across the genus relative to other insects. Visionassociated Rhodopsin genes show conservation of motion detection/tracking functions and variance in the Rhodopsin detecting colors in the blue wavelength ranges. Conclusions: Expanded genomic discoveries reveal the genetics underlying Glossina biology and provide a rich body of knowledge for basic science and disease control. They also provide insight into the evolutionary biology underlying novel adaptations and are relevant to applied aspects of vector control such as trap design and discovery of novel pest and disease control strategies.

ZooKeys, 2015

The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much... more The Bactrocera dorsalis species complex, currently comprising about 90 entities has received much attention. During the last decades, considerable effort has been devoted to delimiting the species of the complex. This information is of great importance for agriculture and world trade, since the complex harbours several pest species of major economic importance and other species that could evolve into global threats. Speciation in Diptera is usually accompanied by chromosomal rearrangements, particularly inversions that are assumed to reduce/eliminate gene flow. Other candidates currently receiving much attention regarding their possible involvement in speciation are reproductive symbionts, such as Wolbachia, Spiroplasma, Arsenophonus, Rickettsia and Cardinium. Such symbionts tend to spread quickly through natural populations and can cause a variety of phenotypes that promote pre-mating and/or post-mating isolation and, in addition, can affect the biology, physiology, ecology and evolution of their insect hosts in

BioMed Research International, 2015

BioMed research international, 2013

Olive mill wastes (OMWs) are high-strength organic effluents, which upon disposal can degrade soi... more Olive mill wastes (OMWs) are high-strength organic effluents, which upon disposal can degrade soil and water quality, negatively affecting aquatic and terrestrial ecosystems. The main purpose of this review paper is to provide an up-to-date knowledge concerning the microbial communities identified over the past 20 years in olive mill wastes using both culture-dependent and independent approaches. A database survey of 16S rRNA gene sequences (585 records in total) obtained from olive mill waste environments revealed the dominance of members of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Actinobacteria. Independent studies confirmed that OMW microbial communities' structure is cultivar dependent. On the other hand, the detection of fecal bacteria and other potential human pathogens in OMWs is of major concern and deserves further examination. Despite the fact that the degradation and detoxification of the olive mill wastes have been mostly investi...

Science, 2014

Africa's Bane Tsetse are blood-feeding, fast-flying flies that transmit a range of Trypanosom... more Africa's Bane Tsetse are blood-feeding, fast-flying flies that transmit a range of Trypanosoma spp. protozoan pathogens, which cause sleeping sickness in humans and their nagana in their livestock. The International Glossina Genome Initiative (p. 380 ) sequenced the genome of Glossina morsitans and identified the genes for many attributes of the tsetse's remarkable biology, including viviparity and the expression of analogs of mammalian milk proteins. Tsetse are host to several specific symbionts that appear to synthesize essential nutrients for the fly and also to hitherto undiscovered parasitoid-derived viruses. Deeper exploration of this genome will reveal what makes these fly species so host- and trypanosome specific.

PLoS Neglected Tropical Diseases, 2014

Tsetse flies (Glossina spp.) are the cyclical vectors of Trypanosoma spp., which are unicellular ... more Tsetse flies (Glossina spp.) are the cyclical vectors of Trypanosoma spp., which are unicellular parasites responsible for multiple diseases, including nagana in livestock and sleeping sickness in humans in Africa. Glossina species, including Glossina morsitans morsitans (Gmm), for which the Whole Genome Sequence (WGS) is now available, have established symbiotic associations with three endosymbionts: Wigglesworthia glossinidia, Sodalis glossinidius and Wolbachia pipientis (Wolbachia). The presence of Wolbachia in both natural and laboratory populations of Glossina species, including the presence of horizontal gene transfer (HGT) events in a laboratory colony of Gmm, has already been shown. We herein report on the draft genome sequence of the cytoplasmic Wolbachia endosymbiont (cytWol) associated with Gmm. By in silico and molecular and cytogenetic analysis, we discovered and validated the presence of multiple insertions of Wolbachia (chrWol) in the host Gmm genome. We identified at least two large insertions of chrWol, 527,507 and 484,123 bp in size, from Gmm WGS data. Southern hybridizations confirmed the presence of Wolbachia insertions in Gmm genome, and FISH revealed multiple insertions located on the two sex chromosomes (X and Y), as well as on the supernumerary B-chromosomes. We compare the chrWol insertions to the cytWol draft genome in an attempt to clarify the evolutionary history of the HGT events. We discuss our findings in light of the evolution of Wolbachia infections in the tsetse fly and their potential impacts on the control of tsetse populations and trypanosomiasis.

GigaScience, 2015

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinf... more Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world's oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits.

Additional file 13: Figure S8.The different OTUs (putative species) assigned to Providencia genus... more Additional file 13: Figure S8.The different OTUs (putative species) assigned to Providencia genus and their relative abundance in the medfly natural populations.

Additional file 4: Figure S1. Analysis of Molecular Variance.

Additional file 1: Table S1. Samples analyzed.

Additional file 11: Figure S6.The different OTUs (putative species) assigned to Klebsiella genus ... more Additional file 11: Figure S6.The different OTUs (putative species) assigned to Klebsiella genus and their relative abundance in the medfly natural populations.

Additional file 10: Figure S5. MDS plot of the microbial profiles of male and female medflies.

Additional file 7: Figure S3. Relative abundances of medfly microbiota at A) Phylum level, B) Cla... more Additional file 7: Figure S3. Relative abundances of medfly microbiota at A) Phylum level, B) Class level, and C) Genus level.