Eitan Ben-dov | Ben Gurion University of the Negev (original) (raw)
Papers by Eitan Ben-dov
![Research paper thumbnail of Corrigendum to “Kinetics and mechanism of plasmid DNA penetration through nanopores” [J. Membr. Sci. 371 (2011) 45–51]](https://attachments.academia-assets.com/42838052/thumbnails/1.jpg)
](
Recent investigations of coral-associated microbial communities have revealed that coral surfaces... more Recent investigations of coral-associated microbial communities have revealed that
coral surfaces are replete with microorganisms that may play important roles in colony wellbeing. In
this study we show that the surfaces of a number of large polyped coral species are covered by a layer
of aggregate-like microorganisms. These microorganisms are embedded in the mucus and in the tissue
of solitary coral Fungia granulosa and in a number of faviid species. They are found on the coral
surface and in the coral tissue. They are dispersed in a patchy distribution, with the highest density
occurring in the area of the polyp mouth. Microscopic investigation revealed that the microorganisms
found on and in tissues of F. granulosa are approximately 5 to 30 μm in diameter and are made up of
unique coccoid bodies of approximately 1 μm in diameter. Transmission electron microscopy (TEM)
revealed that they contain a nucleus, mitochondria and golgi, indicating they are eukaryotic in
nature. The morphological data lead us to identify these organisms as stramenopile protists. This
premise was strengthened by molecular investigation of samples taken from the surface mucus of the
coral F. granulosa. The possible role of these protists is discussed.
Archives of Microbiology, 2007
Environmental Microbiology, 2007
Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resis... more Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resistant Culex quinquefasciatus larvae. The clones expressed different combinations of four genes from Bacillus thuringiensis ssp. israelensis; three genes encoded mosquitocidal toxins (Cry11Aa, Cry4Aa and Cyt1Aa) and the fourth encoded an accessory protein (P20). The cross-resistance spectra of the mosquitoes were similar to the profiles for recombinant B. thuringiensis strains expressing B. thuringiensis toxin genes, but with varied toxicity levels. The toxicity of the recombinants towards resistant mosquito larvae was improved when p20 and cyt1Aa were expressed in combination with cry4Aa and/or cry11Aa. Recombinant pVE4-ADRC, expressing cry4Aa, cry11Aa, p20 and cyt1Aa, was the most active against the resistant Culex, and resistance levels did not exceed fourfold. These results indicate that B. thuringiensis ssp. israelensis genes expressed in a heterologous host such as E. coli can be effective against susceptible and B. thuringiensis-resistant larvae and suppress resistance.
Environmental Microbiology, 2001
Journal of Molecular Biology, 2008
Journal of Invertebrate Pathology, 1991
FEMS Microbiology Letters, 2003
Environmental Microbiology, 2003
Environmental Microbiology, 2007
Current Microbiology, 2001
Journal of the American Mosquito Control Association
Applied and Environmental Microbiology
Applied and Environmental Microbiology
Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated ... more Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phase-contrast and electron microscopy as well as by viable-cell counting. Excreted food vacuoles gradually aggregated, and vegetative growth of B. thuringiensis subsp. israelensis was observed after 7 h as filaments that stemmed from the aggregates. The outgrown cells sporulated between 27 and 42 h. The spore multiplication values in this system are low compared to those obtained in carcasses of B. thuringiensis subsp. israelensis-killed larvae and pupae, but this bioencapsulation represents a n...
Applied and Environmental Microbiology
Various combinations of the genes cryIVA (cry4A), cryIVD (cry11A), and p20 from Bacillus thuringi... more Various combinations of the genes cryIVA (cry4A), cryIVD (cry11A), and p20 from Bacillus thuringiensis subsp. israelensis were introduced into the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 by means of Escherichia coli-Anabaena shuttle vector pRL488p and were expressed under control of two tandem strong promoters, a cyanobacterial promoter (PpsbA) and an E. coli T7 promoter (PA1). Two of the clones carrying cryIVA plus cryIVD, one with p20 and one without p20, displayed toxicity against third-instar larvae of Aedes aegypti at levels greater than any level previously reported for transgenic cyanobacteria.
Diseases of Aquatic Organisms, 2015
Changes of the black band disease (BBD)-associated microbial consortium on the surface of a Favia... more Changes of the black band disease (BBD)-associated microbial consortium on the surface of a Favia sp. coral colony were assessed in relation to the different disease phases. A number of highly active bacterial groups changed in numbers as the BBD disease signs changed. These included Gamma- and Epsilonproteobacteria, Bacteroidetes and Firmicutes groups. One cyanobacterium strain, BGP10_4ST (FJ210722), was constantly present in the disease interface and adjacent tissues of the affected corals, regardless of disease phase. The dynamics of the operational taxonomic units (OTUs) of this BBD-specific strain provide a marker regarding the disease phase. The disease's active phase is characterized by a wide dark band progressing along the tissue-skeleton interface and by numerous bacterial OTUs. Cyanobacterial OTUs decreased in numbers as the disease signs waned, perhaps opening a niche for additional microorganisms. Even when black band signs disappeared there was a consistent though low abundance of the BBD-specific cyanobacteria (BGP10_4ST), and the microbial community of the disease-skeleton interface remained surprisingly similar to the original band community. These results provide an indication that the persistence of even low numbers of this BBD-specific cyanobacterium in coral tissues during the non-active (or subclinical) state could facilitate reinitiation of BBD signs during the following summer. This may indicate that this bacterium is major constituent of the disease and that its persistence and ability to infiltrate the coral tissues may act to facilitate the assembly of the other BBD-specific groups of bacteria.
Current issues in molecular biology, Jan 20, 2015
Culture-independent methods, employed to study the diversity and complexity of microbial communit... more Culture-independent methods, employed to study the diversity and complexity of microbial communities that are based on amplification of rRNA genes with universal primers, include gradient gel electrophoresis (denaturing or temperature), single-strand-conformation polymorphism, restriction fragment length polymorphism, qPCR and high-throughput DNA sequencing. Substituting one or more base(s) within or at the 3'-termi of the universal primers by inosine can overcome some of their shortcomings improving amplification capacity. Universal primer sets do not usually amplify sequences with nucleotide mismatch to the templates, particularly in the last three bases, whereas inosine-modified primers anneal and amplify a variety of rRNA gene sequences. Inosine-containing primers are therefore might be useful to detect more species in diverse prokaryotic populations. The article summarizes the pros and cons of using inosine especially at the 3' termini of universal primers in nucleic ac...
Applied and environmental microbiology, 1997
An extended multiplex PCR method was established to rapidly identify and classify Bacillus thurin... more An extended multiplex PCR method was established to rapidly identify and classify Bacillus thuringiensis strains containing cry (crystal protein) genes toxic to species of Lepidoptera, Coleoptera, and Diptera. The technique enriches current strategies and simplifies the initial stages of large-scale screening of cry genes by pinpointing isolates that contain specific genes or unique combinations of interest with potential insecticidal activities, thus facilitating subsequent toxicity assays. Five pairs of universal primers were designed to probe the highly conserved sequences and classify most (34 of about 60) genes known in the following groups: 20 cry1, 3 cry2, 4 cry3, 2 cry4, 2 cry7, and 3 cry8 genes. The DNA of each positive strain was probed with a set of specific primers designed for 20 of these genes and for cry11A. Twenty-two distinct cry-type profiles were identified from 126 field-collected B. thuringiensis strains. Several of them were found to be different from all publi...
Recent investigations of coral-associated microbial communities have revealed that coral surfaces... more Recent investigations of coral-associated microbial communities have revealed that
coral surfaces are replete with microorganisms that may play important roles in colony wellbeing. In
this study we show that the surfaces of a number of large polyped coral species are covered by a layer
of aggregate-like microorganisms. These microorganisms are embedded in the mucus and in the tissue
of solitary coral Fungia granulosa and in a number of faviid species. They are found on the coral
surface and in the coral tissue. They are dispersed in a patchy distribution, with the highest density
occurring in the area of the polyp mouth. Microscopic investigation revealed that the microorganisms
found on and in tissues of F. granulosa are approximately 5 to 30 μm in diameter and are made up of
unique coccoid bodies of approximately 1 μm in diameter. Transmission electron microscopy (TEM)
revealed that they contain a nucleus, mitochondria and golgi, indicating they are eukaryotic in
nature. The morphological data lead us to identify these organisms as stramenopile protists. This
premise was strengthened by molecular investigation of samples taken from the surface mucus of the
coral F. granulosa. The possible role of these protists is discussed.
Archives of Microbiology, 2007
Environmental Microbiology, 2007
Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resis... more Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resistant Culex quinquefasciatus larvae. The clones expressed different combinations of four genes from Bacillus thuringiensis ssp. israelensis; three genes encoded mosquitocidal toxins (Cry11Aa, Cry4Aa and Cyt1Aa) and the fourth encoded an accessory protein (P20). The cross-resistance spectra of the mosquitoes were similar to the profiles for recombinant B. thuringiensis strains expressing B. thuringiensis toxin genes, but with varied toxicity levels. The toxicity of the recombinants towards resistant mosquito larvae was improved when p20 and cyt1Aa were expressed in combination with cry4Aa and/or cry11Aa. Recombinant pVE4-ADRC, expressing cry4Aa, cry11Aa, p20 and cyt1Aa, was the most active against the resistant Culex, and resistance levels did not exceed fourfold. These results indicate that B. thuringiensis ssp. israelensis genes expressed in a heterologous host such as E. coli can be effective against susceptible and B. thuringiensis-resistant larvae and suppress resistance.
Environmental Microbiology, 2001
Journal of Molecular Biology, 2008
Journal of Invertebrate Pathology, 1991
FEMS Microbiology Letters, 2003
Environmental Microbiology, 2003
Environmental Microbiology, 2007
Current Microbiology, 2001
Journal of the American Mosquito Control Association
Applied and Environmental Microbiology
Applied and Environmental Microbiology
Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated ... more Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fate of spores and toxin inside the food vacuoles was determined at various times after excretion by phase-contrast and electron microscopy as well as by viable-cell counting. Excreted food vacuoles gradually aggregated, and vegetative growth of B. thuringiensis subsp. israelensis was observed after 7 h as filaments that stemmed from the aggregates. The outgrown cells sporulated between 27 and 42 h. The spore multiplication values in this system are low compared to those obtained in carcasses of B. thuringiensis subsp. israelensis-killed larvae and pupae, but this bioencapsulation represents a n...
Applied and Environmental Microbiology
Various combinations of the genes cryIVA (cry4A), cryIVD (cry11A), and p20 from Bacillus thuringi... more Various combinations of the genes cryIVA (cry4A), cryIVD (cry11A), and p20 from Bacillus thuringiensis subsp. israelensis were introduced into the nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 by means of Escherichia coli-Anabaena shuttle vector pRL488p and were expressed under control of two tandem strong promoters, a cyanobacterial promoter (PpsbA) and an E. coli T7 promoter (PA1). Two of the clones carrying cryIVA plus cryIVD, one with p20 and one without p20, displayed toxicity against third-instar larvae of Aedes aegypti at levels greater than any level previously reported for transgenic cyanobacteria.
Diseases of Aquatic Organisms, 2015
Changes of the black band disease (BBD)-associated microbial consortium on the surface of a Favia... more Changes of the black band disease (BBD)-associated microbial consortium on the surface of a Favia sp. coral colony were assessed in relation to the different disease phases. A number of highly active bacterial groups changed in numbers as the BBD disease signs changed. These included Gamma- and Epsilonproteobacteria, Bacteroidetes and Firmicutes groups. One cyanobacterium strain, BGP10_4ST (FJ210722), was constantly present in the disease interface and adjacent tissues of the affected corals, regardless of disease phase. The dynamics of the operational taxonomic units (OTUs) of this BBD-specific strain provide a marker regarding the disease phase. The disease's active phase is characterized by a wide dark band progressing along the tissue-skeleton interface and by numerous bacterial OTUs. Cyanobacterial OTUs decreased in numbers as the disease signs waned, perhaps opening a niche for additional microorganisms. Even when black band signs disappeared there was a consistent though low abundance of the BBD-specific cyanobacteria (BGP10_4ST), and the microbial community of the disease-skeleton interface remained surprisingly similar to the original band community. These results provide an indication that the persistence of even low numbers of this BBD-specific cyanobacterium in coral tissues during the non-active (or subclinical) state could facilitate reinitiation of BBD signs during the following summer. This may indicate that this bacterium is major constituent of the disease and that its persistence and ability to infiltrate the coral tissues may act to facilitate the assembly of the other BBD-specific groups of bacteria.
Current issues in molecular biology, Jan 20, 2015
Culture-independent methods, employed to study the diversity and complexity of microbial communit... more Culture-independent methods, employed to study the diversity and complexity of microbial communities that are based on amplification of rRNA genes with universal primers, include gradient gel electrophoresis (denaturing or temperature), single-strand-conformation polymorphism, restriction fragment length polymorphism, qPCR and high-throughput DNA sequencing. Substituting one or more base(s) within or at the 3'-termi of the universal primers by inosine can overcome some of their shortcomings improving amplification capacity. Universal primer sets do not usually amplify sequences with nucleotide mismatch to the templates, particularly in the last three bases, whereas inosine-modified primers anneal and amplify a variety of rRNA gene sequences. Inosine-containing primers are therefore might be useful to detect more species in diverse prokaryotic populations. The article summarizes the pros and cons of using inosine especially at the 3' termini of universal primers in nucleic ac...
Applied and environmental microbiology, 1997
An extended multiplex PCR method was established to rapidly identify and classify Bacillus thurin... more An extended multiplex PCR method was established to rapidly identify and classify Bacillus thuringiensis strains containing cry (crystal protein) genes toxic to species of Lepidoptera, Coleoptera, and Diptera. The technique enriches current strategies and simplifies the initial stages of large-scale screening of cry genes by pinpointing isolates that contain specific genes or unique combinations of interest with potential insecticidal activities, thus facilitating subsequent toxicity assays. Five pairs of universal primers were designed to probe the highly conserved sequences and classify most (34 of about 60) genes known in the following groups: 20 cry1, 3 cry2, 4 cry3, 2 cry4, 2 cry7, and 3 cry8 genes. The DNA of each positive strain was probed with a set of specific primers designed for 20 of these genes and for cry11A. Twenty-two distinct cry-type profiles were identified from 126 field-collected B. thuringiensis strains. Several of them were found to be different from all publi...