Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii

Background: Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. Results: We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. Conclusion: We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento CientIfico e Tecnologico (CNPq)Coordenacao para Aperfeicoamento de Pessoal de Ensino Superior (CAPES)Fundo de Defesa da Citricultura (FUNDECITRUS

Substrate contribution on carotenoids production in Blakeslea trispora cultivations

The present report gives an insight into the specific changes in the three main carotenoids (lycopene, γ-carotene and β-carotene) occurring in Blakeslea trispora cultures, with regard to medium composition. Various carbon sources and refined natural vegetable oils as co-substrates were used. The different carbon sources greatly affect the final composition of carotenoids, with lactose medium to preferentially accumulate the all-trans-β-carotene. Furthermore, the use of lactose and starch as carbon sources, respectively, gives a first indication that B. trispora is able to metabolise various homo- and hetero-saccharides, thus leading to different carotenoid percentages. The presence of oils as co-substrates resulted in enhanced fungus growth and subsequent higher carotenoid production. Substrates containing linoleic acid or other oils rich in it led to less lycopene accumulation. The data showed that the biosynthesis of lycopene, γ-carotene and β-carotene starts in most cases simultaneously in the early growth phase even in trace amounts and thus may play a role also as antioxidants for the B. trispora cells

Effect of biomass pre-treatment and solvent extraction on β-carotene and lycopene recovery from Blakeslea trispora cells

The production of carotenoids from Blakeslea trispora cells in a synthetic medium has been reported, with the main products being β-carotene, lycopene, and γ-carotene. The effect of biomass pretreatment and solvent extraction on their selective recovery is reported here. Eight solvents of class II and III of the International Conference of Harmonization: ethanol, methanol, acetone, 2-propanol, pentane, hexane, ethyl acetate, and ethyl ether, and HPLC analysis were used for the evaluation of their selectivities towards the three main carotenoids with regard to different biomass pre-treatment. The average Cmax values (maximum concentration of caronoids in a specific solvent) were estimated to 16 mg/L with the five out of eight solvents investigated, whereas methanol, pentane, and hexane gave lower values of 10, 11, and 9 mg/L, respectively. The highest carotenoid yield was obtained in the case of wet biomass, where 44-56% is recovered with one solvent and three extractions and the rest is recovered only after subsequent treatment with acetone; thus, four extractions of 2.5 h are needed. Two extractions of 54 min are enough to recover carotenoids from dehydrated biomass, with the disadvantage of a high degree of degradation. Our results showed that, for maximum carotenoid recovery, ethyl ether, 2-propanol, and ethanol could be successfully used with biomass without prior treatment, whereas fractions enriched in β-carotene or lycopene can be obtained by extraction with the proper solvent, thus avoiding degradation due to time-consuming processes

Frequency dependent non-thermal effects of oscillating electric fields in the microwave region on the properties of a solvated lysozyme system: A molecular dynamics study

The use of microwaves in every day's applications raises issues regarding the non thermal biological effects of microwaves. In this work we employ molecular dynamics simulations to advance further the dielectric studies of protein solutions in the case of lysozyme, taking into consideration possible frequency dependent changes in the structural and dynamic properties of the system upon application of electric field in the microwave region. The obtained dielectric spectra are identical with those derived in our previous work using the Fro hlich- Kirkwood approach in the framework of the linear response theory. Noticeable structural changes in the protein have been observed only at frequencies near its absorption maximum. Concerning Cα position fluctuations, different frequencies affected different regions of the protein sequence. Furthermore, the influence of the field on the kinetics of protein-water as well as on the water-water hydrogen bonds in the first hydration shell has been studied; an extension of the Luzar-Chandler kinetic model was deemed necessary for a better fit of the applied field results and for the estimation of more accurate hydrogen bond lifetime values. © 2017 Floros 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

Molecularly imprinted polymers for cholecystokinin C-terminal pentapeptide

Molecularly imprinted polymers (MIPs) have been prepared from methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as the functional monomer and crosslinker, respectively, for cholecystokinin C terminal pentapeptide (CCK-5), and screened for their rebinding characteristics. They were produced with alterations in the molar ratio of template/monomer/crosslinker and the percentage of net rebinding and the imprinting factor (IF) were used for the evaluation of their imprinting efficacy. The dissociation constant values determined in the case of the polymers with better characteristics, further confirmed the results above. Scanning electron microscopy (SEM) images of MIPs were also obtained in an attempt to correlate their characteristics with polymer’s morphology. Rebinding experiments with CCK-5 and CCK-8 peptides in the case of the polymer that presented higher performance, with net rebinding values 11.9 and 9%, respectively, indicated that this polymer may be a good candidate for the analysis of CCKrelated peptides

Artificial receptor for peptide recognition in protic media:the role of metal ion coordination

The production of molecularly imprinted polymers (MIPs) for the recognition of C-terminal cholecystokinin pentapeptide (CCK-5) in the presence of metal ion is reported. The MIPs were produced under the same molar ratio of template to monomers (acrylamide, N,N′-methylene bisacrylamide) in the presence or absence of nitrilotriacetic acid-nickel (Ni-NTA) complex. Scanning electron microscopy images of MIPs were obtained in an attempt to correlate the adsorption characteristics with polymer's morphology. Subsequently Ni2+ was removed and substituted by other divalent ions such as Mg2+, Fe2+, Zn2+, Co2+ and Cu2+. It was found that polymers containing the metal ion complex with the order Fe-NTA, Ni-NTA and Cu-NTA presented lower dissociation constant values than the rest thus exhibiting stronger guest binding activity. The percentage of theoretical maximum binding sites Bmax was almost the same for these ions, indicating that the ion-template coordination is responsible only for their binding strength and not for the number of active sites. The data showed that the proper ion or the ion exchange in the produced MIPs could lead to materials with interesting recognition abilities regarding CCK-5 or/and other isoforms of CCK hormone