Diet-induced changes in titer support a discrete response of Wolbachia-associated plastic recombination in Drosophila melanogaster

Plastic recombination in Drosophila melanogaster has been associated with a variety of extrinsic and intrinsic factors such as temperature, starvation, and parasite infection. The bacterial endosymbiont Wolbachia pipientis has also been associated with plastic recombination in D. melanogaster. Wolbachia infection is pervasive in arthropods and this infection induces a variety of phenotypes in its hosts, the strength of which can depend on bacterial titer. Here we test the hypothesis that the magnitude of Wolbachia-associated plastic recombination in D. melanogaster depends on titer. To manipulate titer, we raised Wolbachia-infected and uninfected flies on diets that have previously been shown to increase or decrease Wolbachia titer relative to controls. We measured recombination in treated and control individuals using a standard backcrossing scheme with two X-linked visible markers. Our results recapitulate previous findings that Wolbachia infection is associated with increased recombination rate across the yellow-vermillion interval of the X chromosome. Our data show no significant effect of diet or diet by Wolbachia interactions on recombination, suggesting that diet-induced changes in Wolbachia titer have no effect on the magnitude of plastic recombination. These findings represent one of the first steps toward investigating Wolbachia-associated plastic recombination and demonstrate that the phenotype is a discrete response rather than a continuous one.

The lytic siphophage vB_StyS-LmqsSP1 reduces Salmonella Typhimurium isolates on chicken skin

Phage-based biocontrol of bacteria is considered as a natural approach to combat food-borne pathogens. Salmonella spp. are notifiable and highly prevalent pathogens that cause foodborne diseases globally. In this study, six bacteriophages were isolated and further characterized that infect food-derived Salmonella isolates from different meat sources. The siphovirus VB_StyS-LmqsSP1, which was isolated from a cow´s nasal swab, was further subjected to in-depth characterization. Phage-host interaction investigations in liquid medium showed that vB_StyS-LmqsSP1 can suppress the growth of Salmonella spp. isolates at 37°C for ten hours and reduce the bacterial titer at 4°C significantly. A reduction of 1.4 to 3 log units was observed in investigations with two food-derived Salmonella isolates and one reference strain under cooling conditions using MOIs of 10 4 and 10 5 . Phage application on chicken skin resulted in a reduction of about 2 log units in the tested Salmonella isolates from the first three hours throughout a one-week experiment at cooling temperature and an MOI of 10 5 . The one-step growth curve analysis using vB_StyS-LmqsSP1 demonstrated a 60-min latent period and a burst size of 50-61 PFU/infected cell for all tested hosts. Furthermore, the genome of the phage was determined to be free from genes causing undesired effects. Based on the phenotypic and genotypic properties, LmqsSP1 was assigned as a promising candidate for biocontrol of Salmonella Typhimurium in food. Importance: Salmonella enterica is one of the major global causes of foodborne enteritis in humans. The use of chemical sanitizers for reducing bacterial pathogens in the food chain can result in the spread of bacterial resistance. Targeted and clean label intervention strategies can reduce Salmonella contamination in food. The significance of our research demonstrates the suitability of a bacteriophage (vB_StyS-LmqsSP1) for biocontrol of Salmonella enterica serovar Typhimurium on poultry due to its lytic efficacy under conditions prevailing in food production environments.

The Mechanisms of Antibacterial Activity of Magnesium Alloys with Extreme Wettability

In this study, we applied the method of nanosecond laser treatment for the fabrication of superhydrophobic and superhydrophilic magnesium-based surfaces with hierarchical roughness when the surface microrelief is evenly decorated by MgO nanoparticles. The comparative to the bare sample behavior of such surfaces with extreme wettability in contact with dispersions of bacteria cells Pseudomonas aeruginosa and Klebsiella pneumoniae in phosphate buffered saline (PBS) was studied. To characterize the bactericidal activity of magnesium samples with different wettability immersed into a bacterial dispersion, we determined the time variation of the planktonic bacterial titer in the dispersion. To explore the anti-bacterial mechanisms of the magnesium substrates, a set of experimental studies on the evolution of the magnesium ion concentration in liquid, pH of the dispersion medium, surface morphology, composition, and wettability was performed. The obtained data made it possible to reveal two mechanisms that, in combination, play a key role in the bacterial decontamination of the liquid. These are the alkalization of the dispersion medium and the collection of bacterial cells by microrods growing on the surface as a result of the interaction of magnesium with the components of the buffer solution.

ULRASONIC CAVITATION IN TREATMENT OF TROPHIC UICERS

The aim: improvement of trophic ulcer by surgical treatment with ultrasound cavitation combination. Materials and methods. The analysis of complex surgical treatment of trophic ulcers was conducted. Patients were divided into 2 groups, depending on the strategy of treatment. In the first (main) group (n=43) the combination of surgical treatment with ultrasonic cavitation was applied. By comparison, in the second group (n=43) only surgical treatment was applied. The method of treatment of trophic ulcers with the Sonoca 300 device is based on the effect of ultrasonic cavitation, which is a process of mechanical cleaning of the wound from necrotic tissues, while healthy tissue and vessels are not injured. Ultrasound machine SONOCA 300 is intended exclusively for use in human ultrasound surgery and is intended for the following applications: selective tissue dissection, mechanical grinding and cutting of bone tissue, debridement and cleaning of wounds, tissue cutting, tissue coagulation. The exact purpose of the application is determined by which tool is connected. In our case, this is a Macro ultrasonic tip designed for debridement and wound cleansing. Ultrasound is supplied at an operating frequency of 25 kHz, when you press the foot pedal, and simultaneously with the power of ultrasound, the irrigation and aspiration systems are activated. The irrigation solution from the container with the irrigation fluid passes through the tool, at the same time the aspiration of necrotic tissues and fluid, and their direction into the container for aspirate collection. Results and discussions. The ultrasonic cavitation in treatment of trophic ulcers different localization and etiological factors, achieve partial incarnation of ulcer surface on the average in (14,2±0,5) days in the first group and in (16,9±0.6) days in the second group. The level of bacterial titer of ulcer secretion by (16,5±0,6) days was not higher than the commonly accepted critical one in comparison to the classic situation, in the second group it was on the (27,2±0,9) days. Terms of inpatient treatment were: (21,2± 0,9) days in the first group and (27,2±0,9) days in the second group accordingly. The biological properties of ultrasound are due to bactericidal and bacteriostatic action on various microorganisms. In addition to its own bactericidal effect, low-frequency ultrasound significantly enhances the action of many antibiotics and antiseptics, promotes the deposition of drugs in the surface layers of the wound. Under the action of ultrasound increases the phagocytic activity of leukocytes, there is a stimulation of cellular and humeral parts of the immune system, which accelerates the wound process. Conclusion. The usage of ultrasonic cavitation in the complex surgical treatment of trophic ulcers different localization and etiological factors, significantly increases the time of trophic ulcer cleaning, accelerates incarnation by 1.2, reduce the time of treatment of patients with trophic ulcers by 1.8 times in comparison to the classical approach of cleaning, by means of mechanical cleaning of the ulcers from purulence and necrotic tissue by ultrasound of low frequency.

Qtl Mapping of Clavibacter Michiganensis Subsp. Michiganensis (cmm) Resistance Originating from Solanum Pimpinellifolium g1.1554

Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), is considered the most serious bacterial threat in tomato and causes large damages in production areas. Worldwide, Cmm is subjected to quarantine regulations. There is no cultivar on the market containing Cmm resistance. A mapping study was done in order to identify Quantitative Trait Loci (QTL) for resistance in a cross between Solanum lycopersicum and S. pimpinellifolium GI.1554, a wild relative of tomato. Besides wilting, symptoms like stem discoloration and bacterial titer were considered. Using single trait and multi-trait approaches, we have identified five QTL regions that are associated with wilting, stem discoloration and bacterial titer in three different environments. These QTLs can be used in breeding programs to develop cultivars with higher levels of resistance.

Antibacterial FANA oligonucleotides as a novel approach for managing the Huanglongbing pathosystem

Candidatus Liberibacter asiaticus (CLas), a bacterium transmitted by the Asian citrus psyllid, Diaphorina citri, is the causal agent of citrus greening disease, or Huanglongbng (HLB). Currently, vector population suppression with insecticides and tree removal are the most effective strategies for managing the HLB pathosystem. In this study, we assessed the bactericidal capabilities of 2′-deoxy-2′-fluoro-d-arabinonucleic acid antisense oligonucleotides (FANA ASO) both in vitro and in vivo by (1) confirming their capacity to penetrate insect cells, (2) silencing bacterial essential genes, and (3) quantifying reductions in bacterial titer and D. citri transmission. We confirmed that FANA ASO are able to penetrate insect cells without the use of a delivery agent. Expression of an essential gene in the D. citri endosymbiont, Wolbachia (wDi), significantly decreased by 30% following incubation with a wDi-specific FANA ASO. Viability of isolated wDi cells also decreased in response to the FANA ASO treatment. Delivery of a CLas-specific FANA ASO to infected adult D. citri in feeding assays resulted in significant silencing of a CLas essential gene. CLas relative density and transmission were significantly lower among D. citri fed FANA ASO in diet compared to untreated insects. Root infusions of a CLas-specific FANA ASO into infected Citrus trees significantly reduced CLas titer during a 30-day trial. Our results suggest that FANA ASO targeting insect-transmitted plant bacteria or insect endosymbionts may be useful tool for integrated management of agricultural pathogens.

Resistance to ‘Candidatus Liberibacter asiaticus,’ the Huanglongbing Associated Bacterium, in Sexually and/or Graft-Compatible Citrus Relatives

Huanglongbing (HLB) is the most destructive, yet incurable disease of citrus. Finding sources of genetic resistance to HLB-associated ‘Candidatus Liberibacter asiaticus’ (Las) becomes strategic to warrant crop sustainability, but no resistant Citrus genotypes exist. Some Citrus relatives of the family Rutaceae, subfamily Aurantioideae, were described as full-resistant to Las, but they are phylogenetically far, thus incompatible with Citrus. Partial resistance was indicated for certain cross-compatible types. Moreover, other genotypes from subtribe Citrinae, sexually incompatible but graft-compatible with Citrus, may provide new rootstocks able to restrict bacterial titer in the canopy. Use of seedlings from monoembryonic species and inconsistencies in previous reports likely due to Las recalcitrance encouraged us to evaluate more accurately these Citrus relatives. We tested for Las resistance a diverse collection of graft-compatible Citrinae species using an aggressive and consistent challenge-inoculation and evaluation procedure. Most Citrinae species examined were either susceptible or partially resistant to Las. However, Eremocitrus glauca and Papua/New Guinea Microcitrus species as well as their hybrids and those with Citrus arose here for the first time as full-resistant, opening the way for using these underutilized genotypes as Las resistance sources in breeding programs or attempting using them directly as possible new Las-resistant Citrus rootstocks or interstocks.

Wide-ranging transcriptomic analysis of Poncirus trifoliata, Citrus sunki, Citrus sinensis and contrasting hybrids reveals HLB tolerance mechanisms

Huanglongbing (HLB), caused mainly by ‘Candidatus Liberibacter asiaticus’ (CLas), is the most devastating citrus disease because all commercial species are susceptible. HLB tolerance has been observed in Poncirus trifoliata and their hybrids. A wide-ranging transcriptomic analysis using contrasting genotypes regarding HLB severity was performed to identify the genetic mechanism associated with tolerance to HLB. The genotypes included Citrus sinensis, Citrus sunki, Poncirus trifoliata and three distinct groups of hybrids obtained from crosses between C. sunki and P. trifoliata. According to bacterial titer and symptomatology studies, the hybrids were clustered as susceptible, tolerant and resistant to HLB. In P. trifoliata and resistant hybrids, genes related to specific pathways were differentially expressed, in contrast to C. sinensis, C. sunki and susceptible hybrids, where several pathways were reprogrammed in response to CLas. Notably, a genetic tolerance mechanism was associated with the downregulation of gibberellin (GA) synthesis and the induction of cell wall strengthening. These defense mechanisms were triggered by a class of receptor-related genes and the induction of WRKY transcription factors. These results led us to build a hypothetical model to understand the genetic mechanisms involved in HLB tolerance that can be used as target guidance to develop citrus varieties or rootstocks with potential resistance to HLB.